This paper proves the stability of conical K"ahler-Ricci flows on Fano manifolds near a conical K"ahler-Einstein metric, under a weaker energy condition, and provides new proofs of key existence and openness results.
Contribution
It establishes stability of conical K"ahler-Ricci flows under a bounded below Log Mabuchi energy, relaxing previous properness assumptions.
Findings
01
Flow converges to conical K"ahler-Einstein metrics for nearby cone angles.
02
Provides parabolic proofs of Donaldson's openness theorem.
03
Confirms existence conjecture for positive Ricci curvature cases.
Abstract
In this paper, we study the stability of the conical K\"ahler-Ricci flows on Fano manifolds. That is, if there exists a conical K\"ahler-Einstein metric with cone angle 2πβ along the divisor, then for any β′ sufficiently close to β, the corresponding conical K\"ahler-Ricci flow converges to a conical K\"ahler-Einstein metric with cone angle 2πβ′ along the divisor. Here, we only use the condition that the Log Mabuchi energy is bounded from below. This is a weaker condition than the properness that we have adopted to study the convergence before. As corollaries, we give parabolic proofs of Donaldson's openness theorem and his existence conjecture for the conical K\"ahler-Einstein metrics with positive Ricci curvatures.
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Taxonomy
TopicsGeometry and complex manifolds · Geometric Analysis and Curvature Flows
Full text
Stability of the conical Kähler-Ricci flows on Fano manifolds
Jiawei
Xi
(XXX; XXX)
Zusammenfassung
In this paper, we study the stability of the conical Kähler-Ricci flows on Fano manifolds. That is, if there exists a conical Kähler-Einstein metric with cone angle 2πβ along the divisor, then for any β′ sufficiently close to β, the corresponding conical Kähler-Ricci flow converges to a conical Kähler-Einstein metric with cone angle 2πβ′ along the divisor. Here, we only use the condition that the Log Mabuchi energy is bounded from below. This is a weaker condition than the properness that we have adopted to study the convergence in [36, 37]. As corollaries, we give parabolic proofs of Donaldson’s openness theorem [17] and his existence conjecture [18] for the conical Kähler-Einstein metrics with positive Ricci curvatures.
\volumeyear\doiyear
LiuF. LastnameMagdeburg
ZhangF. LastnameHefei
\contactInstitut für Analysis und Numerik, Otto-von-Guericke-Universität Magdeburg, universitätsplatz 2, 39106, Magdeburg, [email protected]
\contactKey Laboratory of Wu Wen-Tsun Mathematics, Chinese Academy of Sciences, and School of Mathematical Sciences,
University of Science and Technology of China, JinZhai Road, 230026, Hefei, [email protected]
\researchsupportedThe first author is supported by the Special Priority Program SPP 2026 “Geometry at Infinity" from the German Research Foundation (DFG), and the second author is supported by NSF in China No.11625106, 11571332 and 11721101.
1 Introduction
Since the conical Kähler-Einstein metrics play an important role in the solution of the Yau-Tian-Donaldson’s conjecture which has been proved by Chen-Donaldson-Sun [6, 7, 8] and Tian [51], the existence and geometry of the conical Kähler-Einstein metrics have been widely concerned. The conical Kähler-Einstein metrics have been studied by Berman [1], Brendle [3], Campana-Guenancia-Pa˘un [4], Donaldson [17], Guenancia-Pa˘un [21], Guo-Song [22, 23], Jeffres [25], Jeffres-Mazzeo-Rubinstein [26], Li-Sun [32], Mazzeo [38], Song-Wang [48], Tian-Wang [52] and Yao [58] etc. For more details, readers can refer to Rubinstein’s article [44].
The conical Kähler-Ricci flows were introduced to attack the existence of the conical Kähler-Einstein metrics. These flows were first proposed in Jeffres-Mazzeo-Rubinstein’s paper (see Section 2.5 in [26]), then Song-Wang (conjecture 5.2 in [48]) made a conjecture on the relation between the convergence of these flows and the greatest Ricci lower bounds of the manifolds. Then the existence, regularity and limit behavior of the conical Kähler-Ricci flows have been studied by Chen-Wang [9, 10], Edwards [19, 20], Liu-Zhang [34], Liu-Zhang [36, 37], Nomura [39], Shen [45, 46], Wang [57] and Zhang [62, 63] etc.
Let M be a Fano manifold with complex dimension n, ω0∈c1(M) be a smooth Kähler metric and D∈∣−λKM∣ (0<λ∈Q) be a smooth divisor. Assume that the Kähler current ω^∈c1(M) admits Lp-density with respect to ω0n for some p>1 and satisfies ∫Mω^n=∫Mω0n. Let γ∈(0,1) and μγ=1−(1−γ)λ. The conical Kähler-Ricci flows take the following form.
[TABLE]
where [D] is the current of integration along D. In [37], we proved the existence of these flows by using smooth approximation (see also [36, 57] for the stronger initial metrics). Let c1,γ(M)=c1(M)−(1−γ)[D] be the twisted first Chern class. Then c1,γ(M)=μγ[ω0] in the Fano case. When μγ is negative or zero, Chen-Wang [10] proved that the corresponding conical Kähler-Ricci flow converges to a conical Kähler-Einstein metric with Ricci curvature μγ and cone angle 2πγ along D. When μγ>0 is sufficiently small and λ⩾1, Li-Sun (see section 2.3 in [32], when λ=1, see also Berman’s work [1] and Jeffres-Mazzeo-Rubinstein’s work [26]) proved that the Log Mabuchi energy Mμγ is proper by using its definition and the property that the Log α-invariant is positive. Then the convergence of the conical Kähler-Ricci flows (CKRFμγ) follows from the arguments in [37]. In other μγ>0 cases, there are obstacles. In [37], under the assumptions that there exists a conical Kähler-Einstein metric with Ricci curvature μγ and cone angle 2πγ along D and no nontrivial holomorphic vector fields tangent to D, we deduced their convergence.
If there exists a conical Kähler-Einstein metric ωφβ with cone angle 2πβ along D, then ωφβ obtains the minimum of the Log Mabuchi energy Mμβ (Corollary 2.10 in [32]), and thus this energy is bounded from blow. Furthermore, when λ⩾1, Li-Sun (Corollary 1.7 in [32]) proved that Mμβ is proper by using Berman’s properness theorem (Theorem 1.5 in [1]) and Donaldson’s openness theorem (Theorem 2 in [17]). For λ>0, Tian-Zhu (Theorem 0.1 in [56]) proved this property by assuming in addition that there is no nontrivial holomorphic vector fields tangent to D. Darvas-Rubinstein solved Tian’s properness conjectures and gave more general properness theorems (Theorem 2.12 in [14]). Under the above assumptions, by using the properness of Mμβ and the uniform Perelman’s estimates, we [36, 37] proved that the conical Kähler-Ricci flows (CKRFμβ) with μβ>0 converge to ωφβ. It is worth noting that the properness of Mμβ is a stronger condition than that Mμβ is bounded from below.
In this paper, we study the stability of the conical Kähler-Ricci flows by only using the weaker condition that the Log Mabuchi energy is bounded form below. We hope that this method can play a positive role in researching the relation between the limit behavior of the (conical) Kähler-Ricci flows and the stability of the manifolds, and studying the existence of the Kähler-Einstein metrics with cone angle zero by using parabolic method. The first problem is related to a parabolic type of Yau-Tian-Donaldson’s conjecture, and the latter one is related to a Tian’s conjecture [50] that the complete Tian-Yau Kähler-Einstein metric on the complement of D should be the limit of the conical Kähler-Einstein metrics as the cone angles tend to zero.
Theorem 1.1**.**
Assume that λ>0 and there is no nontrivial holomorphic vector fields on M tangent to D. If μβ(0<β<1) is positive, we further assume that there is a conical Kähler-Einstein metric with Ricci curvature μβ and cone angle 2πβ along D. Then for any β′ sufficiently close to β, the conical Kähler-Ricci flow (CKRFμβ′) converges to a conical Kähler-Einstein metric with Ricci curvature μβ′ and cone angle 2πβ′ along D in Cloc∞-topology outside D and globally in Cα,β′-sense for any α∈(0,min{1,β′1−1}).
Remark 1.2**.**
When λ⩾1, the assumption that there is no nontrivial holomorphic vector fields tangent to D can be removed according to Theorem 1.5 of Berman [1] (see also Corollary 2.21 in [32]) or Theorem 2.8 of Song-Wang [48].
As in [37], we still use the twisted Kähler-Ricci flows
[TABLE]
to study the conical Kähler-Ricci flows (CKRFμγ), where θε=λω0+−1∂∂log(ε2+∣s∣h2) are smooth closed positive (1,1)-forms, s is the definition section of D and h is a smooth Hermitian metric on −λKM with curvature λω0. We assume that ∣s∣h2<21 by rescaling h.
Let uγ,ε(t) and uγ(t) be the twisted Ricci potentials of ωγ,ε(t) and ωγ(t) with normalization V1∫Me−uγ,ε(t)dVγ,ε(t)=1 and V1∫Me−uγ(t)dVγ(t)=1 respectively. We denote Aμγ,ε(t) and Aμγ(t) be the functionals
[TABLE]
When μγ=0, the functional Aμγ(t) is well-defined (Theorem 3.6) and converges to zero as t tend to ∞ (Theorem 3.7). When μγ>0, from the uniform Perelman’s estimates (Theorem 2.10), the functional Aμγ(t) is well-defined. Furthermore, Aμγ,ε(t) is nondecreasing along (TKRFμγ,ε) (Theorem 2.12), and Aμγ(t) converges to [math] as t tend to ∞ when the Log Mabuchi energy Mμγ is bounded from below (Theorem 2.14).
Remark 1.3**.**
In this paper, when considering the convergence for a sequence of twisted Kähler-Ricci flows as t tend to ∞, we use the functionals Aμγ,ε(t) and Aμγ(t). For a single (twisted) Kähler-Ricci flow, after obtaining the uniform C∞-estimates, we usually use the energy ∥∇u(t)∥L2(M) (see Liu-Wang [35], Phong-Sturm et al.[41, 42, 43] and Tian-Zhu [54]) or the (twisted) Perelman’s entropy (see Collins-Szeˊkelyhidi [11] and Tian-Zhu et al.[55, 53]) to prove the convergence. But in our case, we need consider the convergence for a specific choice sequence of twisted Kähler-Ricci flows. We do not use ∥∇uγ,ε(t)∥L2(M) or the twisted Perelman’s entropy because we can not prove that these functionals converge to [math] uniformly (that is, the convergence depends on μγ and ε). In order to overcome these difficulties, we use the functionals Aμγ,ε(t) and Aμγ(t), especially the convergence of Aμγ(t) and the monotonicity of Aμγ,ε(t), to get the convergence we need. Although the twisted Perelman’s entropies are also monotonous along the twisted Kähler-Ricci flow (see Liu [33] and Collins-Szeˊkelyhidi [11]), we still do not use these entropies because there is no details about them in this conical case. On the manifolds with isolated conical singularity, Dai-Wang [12, 13] and Ozuch [40] developed Perelman’s entropies, and recently Kröncke-Vertman [30] improved the regularities for the minimizers of these entropies and studied their monotonicity along the Ricci de Turck flow.
There are three cases in Theorem 1.1, that is, μβ is negative, zero and positive. The last two cases are difficult.
Case 1. If μβ is negative, μγ is also negative when γ sufficiently close to β. Then we can prove Theorem 1.1 without any assumptions because the uniform estimates along the twisted Kähler-Ricci flows can be deduced directly (see also Chen-Wang’s work [10]).
Case 2. If μβ is zero (that is, λ=1−β1>1 ), then μγ is a negative or sufficiently small positive number when γ close to β. The case of μγ<0 can be solved as in Case 1. There are difficulties when μγ>0, because no direct uniform Perelman’s estimates (independent of μγ) can be used (these estimates depend on μγ1 from the proof of Proposition 5.5 in [36]). For overcoming these difficulties, we need some new arguments.
First, we prove a uniform lower bound independent of μγ for the twisted scalar curvature R(ωμγ,ε(t))−(1−γ)trωμγ,ε(t)θε along (TKRFμγ,ε) when t⩾1 (Lemma 3.1). This uniform lower bound plays an important role in proving the uniform (Perelman’s) estimates (independent of μγ) along (TKRFμγ,ε) for γ sufficiently close to β.
Next, without any assumptions, we prove that there exists uniform constant Dβ such that along the twisted Kähler-Ricci flows (TKRF0,ε),
[TABLE]
for any ε∈(0,21] and t⩾1 (Theorem 3.6). Here we denote φγ,ε(t) is the metric potential of ωγ,ε(t) with background metric ω0, and ωεγ is smooth Kähler metric given in equation (\refTKRF9). For a single (twisted) Kähler-Ricci flow in the case of μβ=0, the bound on the oscillation of metric potential follows from Yau’s C0-estimates for the elliptic complex Monge-Ampère equation. The main tools are the Sobolev inequality, the Poincaré inequality and the Moser iteration (see Lemma 3 in [5] or Theorem 4.6 in [49]). Since we consider a sequence of equations and do not have uniform Poincaré inequality, we here need modified the original proof when we adopt this method. We remark that this bound can also be deduced from Kołodeizj’s Lp-estimates [28, 29]. Then by using estimates (\ref20190223) and the smooth approximation [36, 37], we prove that the conical Kähler-Ricci flow (CKRF0) converges to a Ricci flat conical Kähler-Einstein metric with cone angle 2πβ along D (Theorem 3.7).
At last, by using the continuity of (TKRFμγ,ε) with respect to μγ and ε (Remark 3.10), we deduce the uniform estimates (independent of μγ) along (TKRFμγ,ε) for γ sufficiently close to β. In this process, we mainly use the uniform lower bound of the twisted scalar curvature R(ωμγ,ε(t))−(1−γ)trωμγ,ε(t)θε, the convergence of A0(t), the monotonicity of Aμγ,ε(t) and Dinew’s uniqueness theorem (Theorem 1.2 in [16], see also Berndtsson’s work [2]). We prove the following lemma.
Lemma 1.4**.**
Assume that λ>1 and β=1−λ1 (that is, μβ=0). Then there exists a constant δ(λ)>0 such that
[TABLE]
for any ε∈(0,δ(λ)), γ∈(β,β+δ(λ)) and t∈[δ(λ)1,+∞), where Lβ comes from (\ref20190304).
In [36, 37], we prove the uniform Perelman’s estimates along the twisted Kähler-Ricci flows (TKRFμγ,ε) when μγ>0. These estimates are important in studying the convergence of the conical Kähler-Ricci flows (CKRFμγ). From the proof of Proposition 5.5 in [36], we know that these estimates depend on μγ1. So they are not uniform for μγ∈(0,1). In Lemma 1.4, we have obtained the uniform bound for ∥uγ,ε(t)∥C0(M) when μγ∈(0,η(λ)) with λ>1 and the uniform lower bound for the twisted scalar curvature R(ωμγ,ε(t))−(1−γ)trωμγ,ε(t)θε, then by using Lemma 3.11, we get the uniform Perelman’s estimates independent of μγ along (TKRFμγ,ε) when λ>1.
Theorem 1.5**.**
Let ωγ,ε(t) be a solution of the twisted Kähler Ricci flow (TKRFμγ,ε). When λ>1, there exists uniform constant C such that
[TABLE]
hold for any μγ∈(0,1], t⩾1 and ε∈(0,δ(λ)), where δ(λ) is the constant in Lemma 1.4 and diam(M,ωγ,ε(t)) is the diameter of the manifold with respect to ωγ,ε(t).
Remark 1.6**.**
When λ=1 (resp. 0<λ<1), we can not get the uniform Perelman’s estimates independent of μγ∈(0,1] (resp. μγ∈(1−λ,1]) by this method. Because there is no uniform estimates as (\ref20190223) when μγ=0 (resp. μγ=1−λ), that is, γ=0.
By using Lemma 1.4, the convergence of (CKRFμγ) with γ∈(β,β+δ(λ)) follows from the arguments in [36, 37]. It should be noted that we still don’t need any assumptions in this case. As a corollary of the first two cases, we get the following existence theorem for the conical Kähler-Einstein metrics by using conical Kähler-Ricci flows. This result implies the existence conjecture for the conical Kähler-Einstein metrics with positive Ricci curvatures (when λ=1, they correspond to the cone angles), which is given by Donaldson [18] and proved by Berman, Jeffres-Mazzeo-Rubinstein and Li-Sun (see Theorem 1.5 in [1], Corollary 1 in [26] and Theorem 1.1 in [32]).
Theorem 1.7**.**
Assume λ>1. There exist conical Kähler-Einstein metrics with Ricci curvatures μγ and cone angles 2πγ along D when γ∈(0,1−λ1+δ(λ)) for some δ(λ)>0.
Case 3. If μβ is positive, then μγ is still positive when γ sufficiently close to β. In this case, we can not get the uniform estimates along (TKRFμβ,ε) by no assumptions as in Case 2. We need the assumptions in Theorem 1.1. Let ωφβ=ω0+−1∂∂ˉφβ be a conical Kähler-Einstein metric with Ricci curvature μβ and cone angle 2πβ along D. We approximate φβ with a decreasing sequence of smooth ω0-psh functions φε. Now we introduce the twisted Kähler-Ricci flows
[TABLE]
with γ∈[1−λ1,β] (that is, μγ∈[0,μβ]). By the arguments in section 3 of [37], when ε tend to [math], the limit flows of (TKRFμγ,εβ) are the twisted conical Kähler-Ricci flows
[TABLE]
In the following arguments, we restrict γ∈[1−λ1,β] in the flows (TKRFμγ,εβ) and (CKRFμγβ). In fact, ωβ,εβ(t)=ωβ,ε(t) and ωββ(t)=ωβ(t) by the uniqueness results (see Proposition 2.7 and Theorem 3.7 in [37]). Let uγ,εβ(t) and uγβ(t) be the twisted Ricci potentials of ωγ,εβ(t) and ωγβ(t) with normalization V1∫Me−uγ,εβ(t)dVγ,εβ(t)=1 and V1∫Me−uγβ(t)dVγβ(t)=1 respectively. We denote functionals
[TABLE]
When μγ=0, the functional Aμγβ(t) is well-defined (Theorem 4.14) and converges to zero as t tend to ∞ (Theorem 4.15). When μγ∈(0,μβ], from the uniform Perelman’s estimates (Theorem 4.7), the functional Aμγβ(t) is well-defined. Furthermore, when μγ∈(0,μβ], Aμγ,εβ(t) is nondecreasing along (TKRFμγ,εβ) (Theorem 2.12), and Aμγβ(t) converges to [math] as t tend to ∞ when the Log Mabuchi energy Mμγβ is bounded from below (Theorem 4.8).
First, by similar arguments as in Case 2, we get the uniform estimates along (TKRF0,εβ) (Theorem 4.14) and then obtain the uniform estimates along (TKRFμγ,εβ) when μγ sufficiently close to [math] (Lemma 4.19). We let ψγ,εβ(t) be the metric potential (with specific choice of initial data, see (\refTKRF5)) of ωγ,εβ(t) with background metric ω0. Fix a μβ0>0 obtained in Lemma 4.19, there exists constant Cβ0 independent of ε∈(0,δ) such that
[TABLE]
At the same time, there exists uniform constant C^β0 such that
[TABLE]
for any ε>0, γ∈[β0,β] and t∈[1,+∞) (Proposition 4.9).
Then, by using the uniform estimates (\ref05) and (\ref05001), the continuity of (TKRFμγ,εβ) with respect to μγ and ε (Remark 4.13), the convergence of Aμγβ(t), the monotonicity of Aμγ,εβ(t) and Berndtsson’s uniqueness theorem [2] for the conical Kähler-Einstein metrics with bounded potentials, we deduce the uniform estimates (independent of γ) of ψγ,εβ(t) for γ∈(β0,β). That is, we obtain the following lemma.
Lemma 1.8**.**
Under the same assumptions as in Theorem 1.1. For above μβ0>0, there exists a constant δβ0>0 depending on β0 such that
[TABLE]
for any ε∈(0,δβ0), γ∈[β0,β) and t∈[δβ01,+∞), where Cβ0, C^β0 and ξβ are the constants in (\ref05), (\ref05001) and (\ref2019022301) respectively.
Therefore, there exists a uniform constant Bβ such that for any ε∈(0,δβ0),
[TABLE]
Then by using the arguments in [37], we get the convergence of the conical Kähler-Ricci flows (CKRFμβ). Instead of using the properness of Mμβ in [36, 37], here we only use the weaker condition that Mμβ is bounded from below.
Theorem 1.9**.**
Assume that λ>0 and there is no nontrivial holomorphic fields on M tangent to D. If μβ(0<β<1) is positive, we further assume that there is a conical Kähler-Einstein metric with Ricci curvature μβ and cone angle 2πβ along D. Then the conical Kähler-Ricci flow (CKRFμβ) converges to a conical Kähler-Einstein metric with Ricci curvature μβ and cone angle 2πβ along D in Cloc∞-topology outside divisor D and globally in Cα,β-sense for any α∈(0,min{1,β1−1}).
We denote ψγ,ε(t) is the metric potential (with specific choice of initial data, see (\refTKRF6)) of ωγ,ε(t) with background metric ω0. At last, by similar arguments as above, we prove
Lemma 1.10**.**
Under the same assumptions as in Theorem 1.1. There exists a constant δ>0 such that
[TABLE]
for any ε∈(0,δ), γ∈(β−δ,β+δ) and t∈[δ1,+∞), where Bβ is the constant in (\ref007), ξβ is the constant in (\ref2019022301) and Cβ is the constant in Proposition 4.10.
Then the convergence of the conical Kähler-Ricci flows (CKRFμγ) with γ∈(β−δ,β+δ) follows from the arguments in [36, 37].
It is generally known that Donaldson’s celebrated openness theorem played an important role in solving the Yau-Tian-Donaldson’s conjecture. It was first proposed by Donaldson [17]. Then Yao [59] (see a remark in [36]) and Tian-Zhu [56] gave different proofs by using elliptic methods. Here, as a corollary of Theorem 1.1, we give a parabolic proof of Donaldson’s openness theorem.
Theorem 1.11**.**
(Donaldson’s openness theorem) Assume that λ>0 and there is no nontrivial holomorphic vector fields on M tangent to D. If there is a conical Kähler-Einstein metric with Ricci curvature μβ and cone angle 2πβ along D, then there exist conical Kähler-Einstein metrics with Ricci curvature μβ′ and cone angles 2πβ′ along D for β′ sufficiently close to β.
We give a further remark of our project which is related to the parabolic version of the Yau-Tian-Donaldson’s conjecture.
Remark 1.12**.**
When λ>1. We denote μβ=0 (that is, β=1−λ1) and define a set Ωλ as follows
[TABLE]
From Theorem 1.1, Ωλ contains (β,β0) with some β0∈(β,1), so it is non-empty. Furthermore, Ωλ is open in (β,1). If we can combine the closeness of Ωλ with the stability of the manifolds, then 1∈Ωλ and thus the smooth Kähler-Ricci flow converges to a Kähler-Einstein metric.
When λ=1, we denote κ>0 sufficiently small and νγ=1−(1−γ)(1+κ). We consider the twisted conical Kähler-Ricci flows
[TABLE]
Assume that νβ^=0 (that is, β^=1−1+κ1>0). We define set Ωκ as follows
[TABLE]
By similar arguments as Theorem 1.1, we know that Ωκ is open in (β^,1) and contains (β^,β0) for some β0∈(β^,1). If Ωκ is closed under some stability assumption on the manifold, then 1∈Ωκ which means that the smooth Kähler-Ricci flow converges to a Kähler-Einstein metric.
The above problem can be seen as a parabolic version of the Yau-Tian-Donaldson’s conjecture. In our subsequent work, we will focus on the relation between the closeness of Ωλ (resp. Ωκ) and the K-stability of the manifold.
This paper is organized as follows. In section 2, we recall some results of the twisted Kähler-Ricci flows and conical Kähler-Ricci flows in the literature. In section 3, we study the Case 2 of Theorem 1.1. We first give a uniform lower bound independent of μγ for the twisted scalar curvatures R(ωμγ,ε(t))−(1−γ)trωμγ,ε(t)θε. Then after we get some uniform estimates along the twisted Kähler-Ricci flows (TKRF0,ε) and (TKRFμγ,ε), we prove Lemma 1.4. At last, we prove Lemma 1.8 and Lemma 1.10 after we get some uniform regularities for the twisted Kähler-Ricci flows (TKRFμγ,εβ) in section 5.
Acknowledge: The first author would like to thank Professors Jiayu Li, Miles Simon and Xiaohua Zhu for their useful discussions, constant help and encouragement. He also would like to thank Professor Xiangwen Zhang, Doctors Chao Li and Xishen Jin for their several useful comments. Part of this work was carried out while the first author’s visit to the University of Newcastle and the University of Adelaide in Australia. He is grateful to Professors James McCoy and Thomas Leistner for their invitations, and the universities for their hospitality.
2 Preliminaries
In this section, we give some known results about the twisted Kähler-Ricci flows and the (twisted) conical Kähler-Ricci flows. Let M be a compact Kähler manifold of complex dimension n and D be a smooth divisor. By saying that a closed positive (1,1)-current ω with locally bounded potentials is conical Kähler metric with cone angle 2πβ (0<β<1) along D, we mean that ω is smooth Kähler metric on M∖D. And near each point p∈D, there exists local holomorphic coordinate (z1,⋯,zn) in a neighborhood U of p such that D={zn=0} and ω is asymptotically equivalent to the model conical metric
[TABLE]
Definition 2.1**.**
Let ω0 be a smooth Kähler metric and D⊂M be a smooth divisor which satisfies c1(M)=μ[ω0]+(1−β)[D] with μ∈R. We call ω a conical Kähler-Einstein metric with Ricci curvature μ and cone angle 2πβ along D if it is a conical Kähler metric with cone angle 2πβ along D and satisfies
[TABLE]
Equation (10) is classical outside D and it holds in the sense of currents on M.
There are other definitions of metrics with conical singularities (see [17, 26], etc.). But for conical Kähler-Einstein metrics, these definitions turn out to be equivalent (see Theorem 2 in [26]).
In this paper, by saying that a conical Kähler-Einstein metric with cone angle 2πβ along D we also mean that its Ricci curvature is μβ.
We write ω^=ω0+−1∂∂ˉφ0. Let ωγ=ω0+γ2k−1∂∂ˉ∣s∣h2γ with γ∈(0,1) be the conical Kähler metric which is given by Donaldson [17]. Now, in the Fano case, we list some results proved in [37].
Theorem 2.2**.**
(Theorem 2.8 in [37])
There exists a unique long-time solution ωγ,ε(t) to the twisted Kähler-Ricci flow (TKRFμγ,ε) in the following sense.
•
ωγ,ε(t)* satisfies the twisted Kähler-Ricci flow (TKRFμγ,ε) on (0,∞)×M;*
•
There exists a metric potential \varphi_{\gamma,\varepsilon}(t)\in C^{0}\big{(}[0,\infty)\times M\big{)}\cap C^{\infty}\big{(}(0,\infty)\times M\big{)} such that ωγ,ε(t)=ω0+−1∂∂ˉφγ,ε(t) and t→0+lim∥φγ,ε(t)−φ0∥L∞(M)=0.
Theorem 2.3**.**
(Theorem 1.2 in [37]) There exists a unique long-time solution ωγ(t) to the conical Kähler-Ricci flow (CKRFμγ) in the following sense.
•
For any [δ,T] (0<δ<T<∞), there exists constant C such that
[TABLE]
•
On (0,∞)×(M∖D), ωγ(t) satisfies the smooth Kähler-Ricci flow;
•
On (0,∞)×M, ωγ(t) satisfies equation (CKRFμγ) in the sense of currents;
•
There exists a metric potential \varphi_{\gamma}(t)\in C^{0}\big{(}[0,\infty)\times M\big{)}\cap C^{\infty}\big{(}(0,\infty)\times(M\setminus D)\big{)} such that ωγ(t)=ω0+−1∂∂ˉφγ(t) and t→0+lim∥φγ(t)−φ0∥L∞(M)=0;
•
On [δ,T], there exist constants α∈(0,1) and C∗ such that φγ(t) is Cα on M with respect to ω0 and ∥∂t∂φγ(t)∥L∞(M∖D)⩽C∗.
Remark 2.4**.**
In Theorem 2.3, by saying that ωγ(t) satisfies equation (CKRFμγ) in the sense of currents on M∞:=(0,∞)×M, we mean that for any smooth (n−1,n−1)-form η(t) with compact support in (0,∞)×M, we have
[TABLE]
where the integral on the left side can be written as
[TABLE]
By using the similar arguments as that in the sections 2 and 3 of [37], we have the following results.
Theorem 2.5**.**
There exists a unique long-time solution ωγ,εβ(t) to the twisted Kähler-Ricci flow (TKRFμγ,εβ) in the following sense.
•
ωγ,εβ(t)* satisfies the twisted Kähler-Ricci flow (TKRFμγ,εβ) on (0,∞)×M;*
•
There exists a metric potential \varphi^{\beta}_{\gamma,\varepsilon}(t)\in C^{0}\big{(}[0,\infty)\times M\big{)}\cap C^{\infty}\big{(}(0,\infty)\times M\big{)} such that ωγ,εβ(t)=ω0+−1∂∂ˉφγ,εβ(t) and t→0+lim∥φγ,εβ(t)−φ0∥L∞(M)=0.
Theorem 2.6**.**
There exists a unique long-time solution ωγβ(t) to the conical Kähler-Ricci flow (CKRFμγβ) in the following sense.
•
For any [δ,T] (0<δ<T<∞), there exists constant C such that
[TABLE]
•
On (0,∞)×(M∖D), ωγβ(t) satisfies the smooth twisted Kähler-Ricci flow;
•
On (0,∞)×M, ωγβ(t) satisfies equation (CKRFμγβ) in the sense of currents;
•
There exists a metric potential \varphi^{\beta}_{\gamma}(t)\in C^{0}\big{(}[0,\infty)\times M\big{)}\cap C^{\infty}\big{(}(0,\infty)\times(M\setminus D)\big{)} such that ωγβ(t)=ω0+−1∂∂ˉφγβ(t) and t→0+lim∥φγβ(t)−φ0∥L∞(M)=0;
•
On [δ,T], there exist constants α∈(0,1) and C∗ such that φγβ(t) is Cα on M with respect to ω0 and ∥∂t∂φγβ(t)∥L∞(M∖D)⩽C∗.
Remark 2.7**.**
By Liu-Zhang’s results (Theorem 3.8 in [34], see also Theorem 3.10 in [37]). The solutions ωγ,ε(t) and ωγ,εβ(t) are Cα,β for any α∈(0,min{1,β1−1}) when t>0.
From the proof of Proposition 5.9 in [36], we have the following uniform Sobolev inequalities when the cone angles away from [math].
Theorem 2.8**.**
Assume that n⩾2. For any β0∈(0,1), there exists uniform constant C such that
[TABLE]
hold for any smooth functions v on M, γ∈[β0,1) and ε>0, where dVεγ=n!(ωεγ)n.
Theorem 2.9**.**
Assume that n=1. Then for any β0∈(0,1), there exists uniform constant C such that
[TABLE]
holds for any smooth functions v on M, γ∈[β0,1) and ε>0.
In [36, 37], we proved the uniform Perelman’s estimates for μγ>0, which play an important role in studying the convergence of the conical Kähler-Ricci flows. These estimates mainly depend on the uniform lower bounded of the twisted scalar curvature R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε, the uniform Sobolev inequality CS(M,ωγ,ε(1)) and μγ1. Hence when μγ away from [math], we have the following uniform Perelman’s estimates by using the arguments in [36].
Theorem 2.10**.**
Let ωγ,ε(t) be a solution of the twisted Kähler Ricci flow (TKRFμγ,ε). Then for any 0<μγ1<μγ2⩽1, there exists uniform constant C, such that
[TABLE]
hold for any μγ∈[μγ1,μγ2], t⩾1 and ε>0.
Remark 2.11**.**
The uniform Perelman’s estimates for (TKRFμγ,εβ) can also be established by using the similar arguments as that in [36], but there exist a few details need to be verified in the proof, so we present them in section 4.
In the proof of uniform Perelman’s estimates, we prove that the functional Aμγ,ε(t) with μγ>0 is nondecreasing by using the uniform Poincaré inequality along along the twisted Kähler-Ricci flow (TKRFμγ,ε). Since (μβ−μγ)ωφε+(1−β)θε are positive closed (1,1)-forms when μγ∈(0,μβ], there also exists uniform Poincaré inequality along (TKRFμγ,εβ). So Aμγ,εβ(t) is nondecreasing along (TKRFμγ,εβ) when μγ∈(0,μβ].
Theorem 2.12**.**
When μγ∈(0,1], the functional Aμγ,ε(t) is nondecreasing along the twisted Kähler-Ricci flow (TKRFμγ,ε).
When μγ∈(0,μβ], the functional Aμγ,εβ(t) is nondecreasing along the twisted Kähler-Ricci flow (TKRFμγ,εβ).
Now we recall Aubin’s functionals. Let ϕt be a path with ϕ0=c and ϕ1=ϕ, then
[TABLE]
where dV0=n!ω0n and dVϕ=n!ωϕn. They satisfy 0⩽n1Jω0⩽n+11Iω0⩽Jω0. The twisted Mabuchi energy is defined as
[TABLE]
where uω0 satisfies −Ric(ω0)+kω0+θ=−1∂∂ˉuω0 and V1∫Me−uω0dV0=1. We denote Mμγ,εβ and Mμγ,ε are the twisted Mabuchi energies with twisted forms (μβ−μγ)ωφε+(1−β)θε and (1−γ)θε respectively. Then
[TABLE]
The Log Mabuchi energy is denoted by
[TABLE]
and the twisted Log Mabuchi energy is defined as
[TABLE]
By using Berndtsson’s convexity theorem [2], Li-Sun (Corollary 2.10 in [32]) proved that the conical Kähler-Einstein metric is the minimum point of the Log Mabuchi energy.
Theorem 2.13**.**
(Corollary 2.10 in [32]) If there exists a conical Kähler-Einstein metric ωφβ with cone angle 2πβ along D, then ωφβ obtains the minimum of Mμβ.
Combining the uniform Perelman’s estimates, the Perelman’s non-collapsing theorem and the uniform Poincaré inequality along (TKRFμγ,ε), we get the following estimates and convergence for Aμγ(t) by using the arguments in Lemma 4.3 of [33] or Lemma 3 of [42].
Theorem 2.14**.**
For μγ∈(0,1], there exists constant C such that for t⩾1,
[TABLE]
Furthermore, if Mμγ is bounded form below, then Aμγ(t) converge to [math] as t→+∞.
Remark 2.15**.**
We can also get a similar result for Aμγβ(t) after we prove the uniform Perelman’s estimates along the twisted Kähler-Ricci flow (TKRFμγ,εβ) in section 4.
3 Proof of the case μβ=0
Assume that λ>1. Then μβ=0 when β=1−λ1∈(0,1). In this section, we study the convergence of the conical Kähler-Ricci flow (CKRFμγ) when μγ is positive and sufficiently small. For μγ∈(0,1] (that is, γ∈(β,1]), there is no direct uniform Perelman’s estimates independent of μγ along the twisted Kähler-Ricci flows (TKRFμγ,ε) and hence we do not have the uniform estimates for ψ˙γ,ε(t), so we need some new discussions. In this section, we always assume that μβ=0 and μγ∈[μβ,1] (that is, γ∈[β,1]) unless otherwise specified, and normalize φ0 by
[TABLE]
First, by improving the proof of Proposition 5.1 in [36], we get the uniform lower bound of the twisted scalar curvature R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε when t⩾1.
Lemma 3.1**.**
R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε* are uniformly bounded from below by −4n along the twisted Kähler-Ricci flows (TKRFμγ,ε), that is, for any μγ∈[0,1], ε>0 and t⩾1, we have*
[TABLE]
Beweis.
First, we derive the evolution equation of (t-\frac{1}{2})^{2}\Big{(}R(\omega_{\gamma,\varepsilon}(t))-(1-\gamma)tr_{\omega_{\gamma,\varepsilon}(t)}\theta_{\varepsilon}\Big{)}.
[TABLE]
Let (t0,x0) be the minimum point of (t-\frac{1}{2})^{2}\Big{(}R(\omega_{\gamma,\varepsilon}(t))-(1-\gamma)tr_{\omega_{\gamma,\varepsilon}(t)}\theta_{\varepsilon}\Big{)} on [21,1]×M.
Case1, t0=21, then we have (t-\frac{1}{2})^{2}\Big{(}R(\omega_{\gamma,\varepsilon}(t))-(1-\gamma)tr_{\omega_{\gamma,\varepsilon}(t)}\theta_{\varepsilon}\Big{)}\geqslant 0.
Case2, t0=21, without loss of generality, we can assume R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε⩽0 at (t0,x0). By inequality
[TABLE]
we have
[TABLE]
Then (t_{0}-\frac{1}{2})^{2}\Big{(}R(\omega_{\gamma,\varepsilon}(t_{0}))-(1-\gamma)tr_{\omega_{\gamma,\varepsilon}(t_{0})}\theta_{\varepsilon}\Big{)}\geqslant-2n(t_{0}-\frac{1}{2})\geqslant-n. Hence,
[TABLE]
for any μγ∈[0,1], ε>0 and t∈[21,1]. In particular, when t=1, we have
[TABLE]
Then we consider the lower bound of R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε on [1,∞)×M.
[TABLE]
By maximum principle, on [1,∞)×M, we have
[TABLE]
for any μγ∈[0,1], t⩾1 and ε>0. We complete the proof this lemma.
∎
We write the flows (TKRFμγ,ε) as parabolic Monge-Ampère equations
[TABLE]
where F0 satisfies −Ric(ω0)+ω0=−1∂∂F0 and V1∫Me−F0dV0=1. Let χγ with γ∈(0,1) be the function χγ(ε2+∣s∣h2)=γ1∫0∣s∣h2r(ε2+r)γ−ε2γdr which is given by Campana-Guenancia-Pa˘un [4]. Denote F_{\gamma,\varepsilon}=F_{0}+\log\Big{(}\frac{(\omega^{\gamma}_{\varepsilon})^{n}}{\omega_{0}^{n}}\cdot(\varepsilon^{2}+|s|_{h}^{2})^{1-\gamma}\Big{)}, ϕγ,ε(t)=φγ,ε(t)−kχγ and ωεγ=ω0+−1k∂∂χγ. Equation (23) can be written as
[TABLE]
We first prove the uniform C0-estimates (independent of μγ) for ϕγ,ε.
Lemma 3.2**.**
For any T>0, there exists constant C depending only on ∥φ0∥L∞(M), β, n, ω0 and T such that for any t∈[0,T], ε>0 and μγ∈[0,1] (that is, γ∈[β,1]),
[TABLE]
Beweis.
Since β=1−λ1>0 and γ∈[β,1], from Campana-Guenancia-Pa˘un’s results (see (15) and (25) in [4]), there exist uniform constants A0 and A1, such that for any ε>0 and γ∈[β,1],
[TABLE]
Then we have
[TABLE]
which is equivalent to
[TABLE]
For any δ>0, we denote ϕ~γ,ε(t)=e−μγtϕγ,ε(t)−A0∫0te−μγsds−δt. Let (t0,x0) be the maximum point of ϕ~γ,ε(t) on [0,T]×M. If t0>0, by maximum principle, we have
[TABLE]
which is impossible. Hence t0=0, then
[TABLE]
Let δ→0, we obtain
[TABLE]
Hence there exists a constant C depending only on ∥φ0∥L∞(M), β, n, ω0 amd T such that ϕγ,ε(t)⩽C for any t∈[0,T], ε>0 and μγ∈[0,1]. By similar arguments we can get the uniform lower bound for ϕγ,ε(t).
∎
Then by using the arguments in section 2 of [37] (see also Song-Tian’s work [47]), we have the following lemmas.
Lemma 3.3**.**
For any T>0, there exists a constant C depending only on ∥φ0∥L∞(M), n, β, ω0 and T, such that for any t∈(0,T], ε>0 and μγ∈[0,1],
[TABLE]
Lemma 3.4**.**
For any T>0, there exists a constant C depending only on ∥φ0∥L∞(M), n, β, ω0 and T such that for any t∈(0,T], ε>0 and μγ∈[0,1],
[TABLE]
Hence away from time [math], on any compact subset in M∖D, ωγ,ε are uniformly equivalent to ω0. Then Evans-Krylov-Safonov’s estimates (see [31]) imply the high order regularities.
Lemma 3.5**.**
For any 0<δ<T<∞, k∈N+ and Br(p)⊂⊂M∖D, there exist constants Cδ,T,k,p,r, such that for any ε>0 and μγ∈[0,1],
[TABLE]
where constants Cδ,T,k,p,r depend on ∥φ0∥L∞(M), n, β, δ, k, T, ω0 and distω0(Br(p),D).
Next, we prove the uniform estimates along the twisted Kähler-Ricci flows (TKRF0,ε) and the convergence of the conical Kähler-Ricci flows (CKRF0).
Theorem 3.6**.**
There exists a uniform constant Dβ such that
[TABLE]
for any ε∈(0,21] and t⩾1.
Beweis.
From Lemma 3.3, ∥φ˙β,ε(1)∥C0(M) are uniformly bounded for any ε>0. Then the maximum principle implies that ∥φ˙β,ε(t)∥C0(M) are uniformly bounded for any ε>0 and t⩾1. Since uβ,ε(t)=φ˙β,ε(t)+cβ,ε(t) and V1∫Me−uβ,ε(t)dVβ,ε(t)=1, cβ,ε(t) and uβ,ε(t) are uniformly bounded. Denote φ~β,ε(t)=φβ,ε(t)−V1∫Mφβ,ε(t)dV0, then φ~β,ε(t) satisfies
[TABLE]
By using the Green’s formula with respect to ω0 and −Δω0φ~β,ε(t)⩽n, we have
[TABLE]
for any t⩾0 and ε>0, where constant C depends only on n and ω0. Therefore, there exists a constant A such that A−φ~β,ε(t)⩾1. Since χβ is positive, using integration by parts, we have
[TABLE]
where constant C depends only on β, n and ω0. On the other hand, from Campana-Guenancia-Pa˘un’s work [4], there exist constants δ and C such that
[TABLE]
Since A−φ~β,ε(t) is positive, we conclude that
[TABLE]
Using the normalization (\ref201903), we obtain
[TABLE]
Hence there exists a uniform constant such that for any ε>0 and t⩾0,
[TABLE]
Denote ϕ~β,ε(t)=ϕβ,ε(t)−V1∫Mϕβ,ε(t)dV0. Since χβ is uniformly bounded, by (\ref201911) and (\ref201912), there exist constants B and C such that for any ε>0 and t⩾0,
[TABLE]
Let fεt=B−ϕ~β,ε(t)⩾1. For any α⩾0 and t⩾1,
[TABLE]
Hence the L2-norm of ∇fεt2α+1 with respect to ωεβ can be bounded as follows
[TABLE]
When n⩾2, we denote κ=n−1n and p=α+2. By using the uniform Sobolev inequality (\ref1.5.6), we have
[TABLE]
Hence there exists uniform constant C such that
[TABLE]
Let pi=pi−1κ and p0=n−12n. By Moser’s iteration, we have
[TABLE]
After letting i→∞, we deduce
[TABLE]
On the other hand, taking α=0 in (\ref20190001) and using Hölder inequality, we have
[TABLE]
Combining (\ref201913) with (\refyewan13), for t⩾1, we have
[TABLE]
Since χβ is uniformly bounded, and oscMφβ,ε(t) are uniformly bounded for t∈[0,1],
[TABLE]
for any ε>0 and t⩾0.
Now we denote ϕ^β,ε(t)=ϕβ,ε(t)−V1∫Mϕβ,ε(t)e−F0+Cβ,ε(ε2+∣sh2∣)1−βdV0, where Cβ,ε is the normalization constant such that V1∫Me−F0+Cβ,ε(ε2+∣s∣h2)1−βdV0=1. This normalization implies that for any ε∈(0,21],
[TABLE]
Hence Cβ,ε⩽0. Since V1∫Mϕ^β,ε(t)e−F0+Cβ,ε(ε2+∣s∣h2)1−βdV0=0, we have
[TABLE]
From (\refAAA), we have oscMϕ^β,ε(t)⩽C. Hence we conclude that
[TABLE]
for any ε∈(0,21] and t⩾0. On the other hand, from Lemma 3.4, there exists uniform constant C such that for any ε∈(0,21],
[TABLE]
By using the arguments in the proof of Proposition 3.1 in [36], for any t>1, there exist uniform constant B and C such that
[TABLE]
By Jensen’s inequality, we have
[TABLE]
Hecne [1,t]infV1∫Mϕβ,ε(s)e−F0+Cβ,ε(ε2+∣s∣h2)1−βdV0=V1∫Mϕβ,ε(t)e−F0+Cβ,ε(ε2+∣s∣h2)1−βdV0, and then there exists uniform constant C such that
[TABLE]
for any ε∈(0,21].
When n=1, we can not use the uniform Sobolev inequality (\ref1.5.6). The estimates for oscMφγ,ε(t) follows from Kołodziej’s Lp-estimates [28, 29] directly. The other proofs are similar as above.
∎
Since ∥φ˙β,ε(t)∥C0(M) are uniformly bounded, we have
[TABLE]
for any t⩾1 and ε∈(0,21]. Combining this inequality with (\ref201903040002), we get
[TABLE]
and then obtain the uniform Cloc∞-estimates in M∖D along (TKRF0,ε) for any ε∈(0,21] and t⩾1. At the same time, the twisted Mabuchi energy M0,ε(φβ,ε(t)) are uniformly bounded from below. Then by using the smooth approximation and the arguments in section 7 of [36], we get the convergence of the conical Kähler-Ricci flows (CKRF0). In [10], Chen-Wang obtained this result by considering the conical Kähler-Ricci flow directly. In fact, by using similar arguments as above, we get the following convergence theorem.
Theorem 3.7**.**
Let M be a Kähler manifold, ω0 be a smooth Kähler metric and D be a smooth divisor. Assume that the Kähler current ω^∈c1(M) admits Lp-density with respect to ω0n for some p>1 and satisfies ∫Mω^n=∫Mω0n. If c1(M)=(1−γ)[D] with γ∈(0,1), then the conical Kähler-Ricci flow (CKRF0) converges to a Ricci flat conical Kähler-Einstein metric with cone angle 2πγ along D in Cloc∞-topology outside divisor D and globally in Cα,γ-sense for any α∈(0,min{1,γ1−1}).
Proposition 3.8**.**
There exists a constant δ^, such that for any t∈[0,δ^), ε∈[0,21] and z∈M, φγ,ε(t) is increasing with respect to γ∈[β,1].
Beweis.
We first consider the case ε∈(0,21]. By Kołodziej’s results [28, 29], there exists a Hölder continuous solution uγ,ε to the equation
[TABLE]
and uγ,ε satisfies
[TABLE]
where the normalization constant C^ is uniformly bounded independent of ε and γ, constant C depends only on ∥φ0∥L∞(M), β and F0. We define function
[TABLE]
where
[TABLE]
From the arguments in the proof of Proposition 3.5 in [37], we know that ψγ,ε(t) is a subsolution of equation (\refTKRF7) and hence
[TABLE]
where h1(t) with h1(0)=0 is a continuous function independent of γ and ε. Then there exists δ^, such that h1(t)>−21 for any t∈[0,δ^]. By the normalization (\refnom0), we have
[TABLE]
for any γ∈[β,1], ε∈(0,1], t∈(0,δ^) and z∈M. For β⩽γ1⩽γ2⩽1, on [0,δ^]×M,
[TABLE]
Then the maximum principle implies that φμγ1,ε(t)⩽φμγ2,ε(t) for any ε∈(0,21], t∈(0,δ^) and z∈M. Letting ε→0, we get the ε=0 case.
∎
Proposition 3.9**.**
Let {εi}∈[0,21] and {γi}∈[β,1] (that is, μγi∈[0,1]). We assume that εi and γi converge to ε∞ and γ∞ respectively. For any [δ,T](0<δ<T<∞), there exists α∈(0,1) such that φγi,εi(t) converge to φγ∞,ε∞(t) in Cα′-sense on [δ,T]×M for any α′∈(0,α), and on (0,∞)×(M∖D) the convergence is in Cloc∞-sense.
Beweis.
On [δ,T]×M with 0<δ<T<∞, by Lemma 3.2 and Lemma 3.3, φγi,εi(t) and φ˙γi,εi(t) are uniformly bounded. By Kołodziej’s Lp-estimates [28, 29], there exists α∈(0,1) such that ∥φγi,εi(t)∥Cα(M,ω0) are uniformly bounded. Then there exists a subsequence φγik,εik(t) converge to a function φ∞(t) in Cα′-sense on [δ,T]×M with α′∈(0,α), and in Cloc∞-sense on (0,∞)×(M∖D) from Lemma 3.5. Furthermore, on (0,∞)×M (or (0,∞)×(M∖D) if ε∞=0), φ∞(t) satisfies equation
[TABLE]
We claim that φ∞(t)=φγ∞,ε∞(t). Fix γ, t and z∈M, by Proposition 3.3 in [37], φγ,ε(t) is decreasing as ε↘0. Combining this with Proposition 3.8 and (\ref201906002), we have
[TABLE]
on [0,δ^)×M for any γik and εik. Let k→∞, we have
[TABLE]
Since φ1,21(t) converge to φ0 in L∞-sense as t→0 and h1(0)=0, φ∞(t) converge to φ0 in L∞-sense as t→0. By the uniqueness results (see Proposition 2.7 or Theorem 3.7 in [37]), we prove the claim. Next, we prove that φγi,εi(t) converge to φγ∞,ε∞(t) in Cα′-sense on [δ,T]×M for any α′∈(0,α). If this is not true, then there exists α0∈(0,α), ϵ0>0 and a sequence φγjk,εjk(t) such that
[TABLE]
Since ∥φγjk,εjk(t)∥Cα′([δ,T]×M) are uniformly bounded for some α′∈(α0,α), there exists a subsequence which we also denote it by φγjk,εjk(t) such that φγjk,εjk(t) converge in Cα0-sense to a function φ~∞(t) as k→∞ and
[TABLE]
By the similar arguments as above, φ~∞(t) is also a solution of the equation (\refTKRF7) with μγ∞ and ε∞. However, φ~∞(t)≡φγ∞,ε∞(t) by (\ref3.22.6116), which is impossible by the uniqueness theorem. Hence we prove the Cα-convergence. From the uniform Cloc∞-estimates for φγi,εi(t), we can also prove that φγi,εi(t) converge to φγ∞,ε∞(t) in Cloc∞-topology on (0,∞)×(M∖D) by the similar arguments.
∎
Remark 3.10**.**
As a consequence of Proposition 3.9, on [δ,T]×M, the Cα-norm of φγ,ε(t) on [δ,T]×M (for some α∈(0,1)) is continuous with respect to γ∈[β,1] and ε∈[0,21]. Furthermore, If we fix ε∈(0,21], then the C∞-norm of φγ,ε(t) on [δ,T]×M is continuous with respect to γ∈[β,1].
Straightforward calculation shows that
[TABLE]
where J is the complex structure on M.
Lemma 3.11**.**
If ∥uγ,ε(t)∥C0(M)⩽A on [T1,T2] with (1<T1<T1+1<T2⩽∞). Then there exists uniform constant C depending only on ∥φ0∥L∞(M), β, n, ω0 and A such that on M×[T1+1,T2],
[TABLE]
Beweis.
We first prove that there exists uniform constant C such that
[TABLE]
Calculation shows that uγ,ε(t) can be written as
[TABLE]
where Cγ,ε,1 is the normalization constant such that V1∫Me−uγ,ε(1)dVγ,ε(1)=1. By Lemma 3.2 and
Lemma 3.3, Cγ,ε,1 and uγ,ε(1) are uniformly bounded by a constant C depending only on ∥φ0∥L∞(M), β, n and ω0, and hence Aμγ,ε(1) are uniformly bounded. Since Aμγ,ε(t) is increasing along (TKRFμγ,ε) when μγ>0, Aμγ,ε(t) is uniformly bounded from below for any ε>0, γ∈(β,1] and t⩾1. On the other hand, by Jensen’s inequality, Aμγ,ε(t)⩽0.
Let Hγ,ε(t)=(t−T1)∣∇uγ,ε(t)∣ωγ,ε(t)2+23uγ,ε2(t) and (t0,x0) be the maximum point of Hγ,ε(t) on [T1,T1+1]×M. Combining (\ref3.22.16) with
[TABLE]
we obtain
[TABLE]
where constant C depends only on A, ∥φ0∥L∞(M), β, n and ω0.
Case1, t0=T1. Then (t−T1)∣∇uγ,ε(t)∣ωγ,ε(t)2⩽23uγ,ε2(T1)⩽23A2.
Case2, t0>T1. By the maximum principle, we have ∣∇uγ,ε(t0,x0)∣ωγ,ε(t0)2⩽C. Hence (t−T1)∣∇uγ,ε(t)∣ωγ,ε(t)2⩽C.
From the above two cases, (t−T1)∣∇uγ,ε(t)∣ωγ,ε(t)2⩽C on [T1,T1+1]×M. Obviously ∣∇uγ,ε(T1+1)∣ωγ,ε(T1+1)2 are uniformly bounded by a constant C which depends only on A, ∥φ0∥L∞(M), β, n and ω0.
Since Δωγ,ε(t)uγ,ε(t)=−R(ωγ,ε(t))+μγn+(1−γ)trωγ,ε(t)θε, we only need to prove the uniform upper bound of −Δωγ,ε(t)uγ,ε(t).
We take Gγ,ε(t)=(t−T1)2(−Δωγ,ε(t)uγ,ε(t))+2(t−T1)2∣∇uγ,ε(t)∣ωγ,ε(t)2. According to (LABEL:3.22.16) and
[TABLE]
the evolution equation of Gγ,ε(t) can be controlled as
[TABLE]
where constant C0 depends only on A, ∥φ0∥L∞(M), β, n and ω0. Assuming that (t0,x0) is the maximum point of Gγ,ε(t) on [T1,T1+1]×M.
Case1, t0=T1, then (t−T1)2(−Δωγ,ε(t)uγ,ε(t))⩽0.
Case2, t0>T1. We assume −Δωγ,ε(t)uγ,ε(t)>0 at (t0,x0) without loss of generality. We claim that (t0−T1)2(−Δωγ,ε(t0)uγ,ε(t0,x0))⩽n(3+C0). If not, by the maximum principle, we have
[TABLE]
We get a contradiction. From these two cases, we conclude that −(t−T1)2Δωγ,ε(t)uγ,ε(t)⩽C on [T1,T1+1]×M for some constant C depending only on A, ∥φ0∥L∞(M), β, n and ω0. Furthermore, R(ωγ,ε(T1+1))−(1−γ)trωγ,ε(T1+1)θε=−Δωγ,ε(T1+1)uγ,ε(T1+1)+μγn⩽C.
Since ∥uγ,ε(t)∥C0(M)⩽A on [T1,T2], there exists a uniform constant B>1 such that uγ,ε(t)>−B on [T1,T2]. Define Hγ,ε(t)=uγ,ε(t)+2B∣∇uγ,ε(t)∣ωγ,ε(t)2. By arguments in [36],
[TABLE]
Taking δ<1, since θε(graduγ,ε(t),J(graduγ,ε(t)))⩾0, we have
[TABLE]
From (\ref1.5.2), we have
[TABLE]
where C2 depends only on A, ∥φ0∥L∞(M), β, n and ω0. The maximum principle implies that Hγ,ε(t)⩽max(C2,2(2B+C1)δ−1) for t∈[T1+1,T2]. We get the first inequality in (\ref3.22.18).
Now we prove the second inequality. Let Gγ,ε(t)=uγ,ε(t)+2B−Δωγ,ε(t)uγ,ε(t)+2Hγ,ε(t).
[TABLE]
Since θε is semi-positive,
[TABLE]
By using inequality
[TABLE]
we have
[TABLE]
Since uγ,ε(T1+1)+2B−Δωγ,ε(T1+1)uγ,ε(T1+1) are bounded uniformly, by the maximum principle, there exists a uniform constant C depending only on A, ∥φ0∥L∞(M), β, n and ω0 such that Gγ,ε(t)⩽C for any t∈[T1+1,T2]. Hence we get −Δωγ,ε(t)uγ,ε(t)⩽C(uγ,ε(t)+2B) and hence R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε⩽C(uγ,ε(t)+C) on [T1+1,T2]×M.
∎
Now, we recall some uniform Sobolev inequalities along the twisted Kähler-Ricci flows (TKRFμγ,ε). From the proof of Theorem 6.1 in [36] (see also [35, 60, 61]), when t⩾1, the Sobolev constants along (TKRFμγ,ε) depend only on n, ω0, Mmax(R(ωγ,ε(1))−(1−γ)trωγ,ε(1)θε)− and CS(M,ωγ,ε(1)), where the latter two are uniformly bounded from Theorem 2.8, Lemma 3.1 and Lemma 3.4 . Hence we have the following Sobolev inequality.
Theorem 3.12**.**
Let M be Fano manifold of complex dimension n≥2 and ωγ,ε(t) be a solution of the twisted Kähler-Ricci flow (TKRFμγ,ε). There exist uniform constants A and B depending only on ∥φ0∥L∞(M), β, n and ω0 such that
[TABLE]
for any v∈W1,2(M,ωγ,ε(t)), γ∈(β,1], ε>0 and t≥1.
By using Hus’s work (see Theorem 1 in [24]) and the arguments in the proof of Theorem 6.1 in [36] (see also [35, 60, 61]), we have the following uniform Sobolev inequality for n=1.
Theorem 3.13**.**
Let M be a Fano manifold of complex dimension 1 and ωγ,ε(t) be a solution of the twisted Kähler-Ricci flow (TKRFμγ,ε). For n0>1, there exist uniform constants A and B depending only on ∥φ0∥L∞(M), β, n0 and ω0 such that
[TABLE]
for any v∈W1,2(M,ωγ,ε(t)), γ∈(β,1], ε>0 and t≥1.
Combining these uniform Sobolev inequalitities with Lemma 3.1, we have the following Theorem by following Jiang’s work (Theorem 1.12 in [27]).
Theorem 3.14**.**
Let M be a Fano manifold of complex dimension n and ωγ,ε(t) be a solution of the twisted Kähler-Ricci flow (TKRFμγ,ε). Let f be a non-negative Lipschitz continuous function on [0,∞)×M satisfying
[TABLE]
on [0,∞)×M in the weak sense, where a⩾0. For p>0, there exists a constant C depending only on ∥φ0∥L∞(M), β, a, p, ω0 and n0 (n0=n if n⩾2, n0>1 if n=1) such that
[TABLE]
holds for any T<t<T+1 with T⩾1, γ∈(β,1] and ε>0.
Let ωφβ=ω0+−1∂∂ˉφβ be the Ricci flat conical Kähler-Einstein metric obtained in Theorem 3.7, then φβ∈C0(M)∩C∞(M∖D) satisfies
[TABLE]
where C^β is the normalization constant such that V1∫Me−F0+C^β∣s∣h2(1−β)dV0=1. By using the normalization of V1∫Me−F0dV0=1, we conclude that C^β=−logV1∫Me−F0∣s∣h2(1−β)dV0⩽0. By Kołodziej’s Lp-estimates [28, 29], we have
[TABLE]
At the same time, by Guenancia-Pa˘un’s results [4, 21] (see also Liu-Zhang [34]), there exists constant Mβ such that
[TABLE]
We denote
[TABLE]
where Dβ is the constant in (\ref1904000). Next, we prove Lemma 1.4.
Proof of Lemma 1.4. If this lemma is not true. For δ1<min(21,1−β), there exist ε1∈(0,δ1), γ1′∈(β,β+δ1) and t1′∈[δ11,∞), such that
[TABLE]
Assume t1′∈[δ11,T1], then we have
[TABLE]
Theorem 3.6 and Remark 3.10 imply that there exists γ1∈(β,γ1′), such that
[TABLE]
Hence there exists t1∈[δ11,T1] such that
[TABLE]
and then
[TABLE]
For δ2=min(21,T1+11,ε1,γ1−β), there exist ε2∈(0,δ2), γ2′∈(β,β+δ2) and t2′∈[δ21,∞), such that
[TABLE]
Assume t2′∈[T1+1,T2], we have
[TABLE]
Theorem 3.6 and Remark 3.10 imply that there exists γ2∈(β,γ2′), such that
[TABLE]
Hence there exists t2∈[T1+1,T2] such that
[TABLE]
and then
[TABLE]
After repeating above process, we get a subsequence φγi,εi(ti) with εi↘0, γi↘β, ti↗∞ and ti∈[Ti−1+1,Ti] satisfying
[TABLE]
and
[TABLE]
We claim that there exists a uniform constant A depending only on ∥φ0∥L∞(M), β, ω0 and n, such that
[TABLE]
Combining the arguments below (\ref201903120015) with Lemma 3.1, we have
[TABLE]
Then for the above sequence, we have
[TABLE]
Integrating form t to Ti−1+1 on both sides, where t∈[Ti−1,Ti−1+1], we obtain
[TABLE]
Hence there exists a uniform constant C such that
[TABLE]
for any t∈[Ti−1,Ti−1+1], εi and γi. By using Lemma 3.1 again, we have
[TABLE]
for any γ∈[β,1], ε>0 and t⩾1. Since
[TABLE]
the twisted Mabuchi energy Mμγ,ε is decreasing along the twisted Kähler-Ricci flow (TKRFμγ,ε). By Lemma 3.2 and Lemma 3.3, we have
[TABLE]
for any γ∈[β,1], ε>0 and t⩾1. On the other hand, we write equation (\refTKRF7) as
[TABLE]
Integrating above equation on both sides, there exists uniform constant such that for any t⩾1, γ∈[β,1] and ε>0,
[TABLE]
By using (\ref1915), we have
[TABLE]
for any t∈[Ti−1+1,Ti], γi and εi. Hence ∥φ˙γi,εi(t)−μiφγi,εi(t)∥C0(M) are uniformly bounded on [Ti−1+1,Ti]. Combining this with (\ref1915), we have
[TABLE]
Integrating (\ref1916001) from Ti−1 to Ti−1+1 on both sides, we have
[TABLE]
for any γi and εi. Straightforward calculation shows that
for any t∈(Ti−1,Ti−1+1], γi and εi by using (\ref201903060000001) and (\ref201903060000002). Hence there exists uniform constant C such that for any γi, εi and t∈[Ti−1+41,Ti−1+1],
[TABLE]
By Jensen’s inequality and normalization V1∫Me−uγ,ε(t)dVγ,ε(t)=1, we have
[TABLE]
When μγ⩾0, combining this with (\ref2019030701), we control the evolution of uγi,εi(t) as
[TABLE]
Then we have
[TABLE]
Integrating form t to Ti−1+1 on both sides, where t∈[Ti−1+41,Ti−1+1], we obtain
[TABLE]
Hence there exists a uniform constant C such that
[TABLE]
for any t∈[Ti−1+41,Ti−1+1], εi and γi. Since uγ,ε(t)=φ˙γ,ε(t)+c^γ,ε(t), where c^γ,ε(t) is only a function of time t, from (\ref191911) and (\ref190312005), we have
[TABLE]
for any t∈[Ti−1+41,Ti−1+1], εi and γi. By using (\ref2019030701) again, we have
[TABLE]
Hence
[TABLE]
Integrating form t to Ti−1+1 on both sides, where t∈[Ti−1+41,Ti−1+1], we obtain
Integrating form t to Ti−1+1 on both sides, where t∈[Ti−1+41,Ti−1+1], we obtain
[TABLE]
Hence
[TABLE]
Integrating form t to Ti−1+1 on both sides of (\ref1903120011) and (\ref1903120012), where t∈[Ti−1+41,Ti−1+1],
[TABLE]
From above arguments, for any t∈[Ti−1+41,Ti−1+1], εi and γi, we get
[TABLE]
Let ψγi,εi(t)=φγi,εi(t)+C~γi,εieμγit and denote
[TABLE]
where F_{\gamma_{i},\varepsilon_{i}}(1)=F_{0}+\log\Big{(}\frac{\omega_{\gamma_{i},\varepsilon_{i}}^{n}(1)(\varepsilon^{2}+|s|_{h}^{2})^{1-\gamma_{i}}}{\omega_{0}^{n}}\Big{)}. We know that C~γi,εi is well-defined from the uniform Perelman’s estimates (here the estimates depend on μγi) and that ψγi,εi(t) is a solution of equation (\refTKRF7) with initial data φ0+C~γi,εi. From (\ref201903120015), uγi,εi(t) can be written as
[TABLE]
where Cγi,εi,1 is the normalization constant such that V1∫Me−uγi,εi(1)dVγi,εi(1)=1. By Lemma 3.2 and
Lemma 3.3, Cγi,εi,1 and uγi,εi(1) are uniformly bounded independent of εi and γi. Let uγi,εi(t)=ψ˙γi,εi(t)+cγi,εi(t). Then
[TABLE]
Next, we prove that there exists a uniform constant C such that for any εi and γi,
[TABLE]
We let
[TABLE]
Through computing, we have
[TABLE]
Integrating this equality form 1 to t on both sides, we have
[TABLE]
Putting (\ref201903120016) and (\ref333) into above equality, we have
[TABLE]
Therefore, by using (\ref2019030701), there exists uniform constant C such that for any γi, εi and t∈[Ti−1+41,Ti−1+1],
[TABLE]
Then we conclude that ∥ψ˙γi,εi(t)∥C0(M) is uniformly bounded on [Ti−1+41,Ti−1+1] by using (\ref190312006). Since oscMψγi,εi(t)=oscMφγi,εi(t), oscMψγi,εi(t) are uniform bounded on [Ti−1+41,Ti−1+1]. We have proved that there exists constant C depending only on Lβ, n, ∥φ0∥L∞(M), β and ω0 such that
[TABLE]
From above estimates, we also have
[TABLE]
which implies that ∥μγiψγi,εi(t)∥C0(M) are uniformly bounded on [Ti−1+41,Ti−1+1]. From the arguments in Lemma 2.3 of [37], there exist uniform constant B and C such that, on (Ti−1+41,Ti−1+1]×M, we have
[TABLE]
where (t1,z1) is the minimum point of ψγi,εi(t) on [Ti−1+41,Ti−1+1]×M, and we use that χγ with γ∈[β,1) can be uniformly bounded by a constant C depending only on β in the second inequality. So on t∈[Ti−1+21,Ti−1+1]×M, we have
[TABLE]
Hence we prove the claim (\ref1916).
From (\ref1916), for t∈[Ti−1+21,Ti], γi and εi, we have
[TABLE]
Combining this with (\ref192202), we conclude that the C0-norms of φ˙γi,εi(t)−μγiφγi,εi(t) and then ϕ˙γi,εi(t)−μγiϕγi,εi(t) are uniformly bounded on [Ti−1+21,Ti]. So we obtain
[TABLE]
where we use that Fγ,ε with γ∈[β,1) can be uniformly bounded by a constant C depending only on β, n and ω0. Hence for any t∈[Ti−1+21,Ti], γi and εi, we have
[TABLE]
By Evans-Krylov-Safonov’s estimates, for any Br(p)⊂⊂M∖D, there is uniform constant Ck,p,r such that
[TABLE]
for any t∈[Ti−1+43,Ti], γi and εi. In particular, for any K⊂⊂M∖D, we have
[TABLE]
for any i and k∈N+. Then φγi,εi(ti) (by taking a subsequence if necessary) converge to a function φβ(∞)∈C∞(M∖D) in Cloc∞-topology in M∖D. By estimates (\ref192400010101), the Lebesgue Dominated Convergence theorem implies that ∫M(ω0+−1∂∂ˉφβ(∞))n=∫Mω0n.
Let uβ(∞) be the twisted Ricci potential of ωφβ(∞)=ω0+−1∂∂ˉφβ(∞). For any K⊂⊂M∖D, since ωγi,εi(ti) are uniformly equivalent to ω0 on K by (\ref192400010101) and μγi tend to [math], we conclude that uβ(∞) satisfies
[TABLE]
By the Lebesgue Dominated Convergence theorem again, we get that V1∫Me−uβ(∞)dVβ(∞)=1. Since Aμγ,ε(t) is increasing along (TKRFμγ,ε) with μγ>0, for any j<i,
[TABLE]
the second inequality due to Jensen’s inequality. Let i→∞, we have
[TABLE]
Since μβ=0, from Theorem 3.7, the conical Kähler-Ricci flow (CKRFμβ) converge to a conical Kähler-Einstein metric. By using the normalization of the twisted Ricci potential uβ(t), we conclude that uβ(t) converge to [math] in Cloc∞-topology on M∖D, and hence Aμβ(t) converge to [math]. This implies that
[TABLE]
after letting j→∞. Since log is strictly concave, we conclude uβ(∞)=0 by using Jensen’s inequality and its normalization. This means that ωφβ(∞) is a Ricci flat conical Kähler-Einstein metric with cone angle 2πβ along D, hence φβ(∞) satisfies equation (\ref201902230101). Then Dinew’s uniqueness theorem (Theorem 1.2 in [16]) implies that φβ(∞)=φβ+C. Letting i→∞ in (\ref2000019), we get
[TABLE]
This leads to a contradiction. Thus Lemma 1.4 is proved.
We denote constant
[TABLE]
where F_{\gamma,\varepsilon}(1)=F_{0}+\log\Big{(}\frac{\omega_{\gamma,\varepsilon}^{n}(1)(\varepsilon^{2}+|s|_{h}^{2})^{1-\gamma}}{\omega_{0}^{n}}\Big{)}. Since μγ>0, C~γ,ε are well-defined and uniformly bounded by the uniform Perelman’s estimates (independent of ε but depend on μγ). We denote ψγ,ε(t)=φγ,ε(t)+C~γ,εeγt, which is a solution to the equation
[TABLE]
From the Proposition 4.5 in [37], we know that ∥ψ˙γ,ε(t)∥C0(M) are uniform bounded for any ε>0 and t⩾1. For any γ∈(β,β+δ(λ)) obtained in Lemma 1.4, we can get the uniform C0-estimates and Laplacian C2-estimates of ψγ,ε(t) for any ε∈(0,δ(λ)) and t⩾1. Hence the twisted Mabuchi energy Mμγ,ε are uniformly bounded from below along the twisted Kähler-Ricci flow (TKRFμγ,ε), that is, there exists uniform constant C such that for ε∈(0,δ(λ)) and t⩾1,
[TABLE]
Then by using the arguments in [36, 37], we deduce the convergence of the conical Kähler-Ricci flows (CKRFμγ) with γ∈(β,β+δ(λ)).
Proof of Theorem 1.5. Combining Lemma 1.4, Lemma 3.1 with Lemma 3.11, we obtain that ∣R(ωγ,ε(t))−(1−γ)trωγ,ε(t)θε∣ and ∥uγ,ε(t)∥C1(ωγ,ε(t)) are uniform bounded for any ε∈(0,δ(λ)), γ∈(β,β+δ(λ)) and t∈[δ(λ)1,+∞). From Lemma 1.4, we also know that there exists uniform constant C such that
[TABLE]
hold for any ε∈(0,δ(λ)), γ∈(β,β+δ(λ)) and t∈[δ(λ)1,+∞). Combining this with (\ref192202), we conclude that ∥φ˙γ,ε(t)−μγφγ,ε(t)∥C0(M) and then ∥ϕ˙γ,ε(t)−μγϕγ,ε(t)∥C0(M) are uniform bounded. So
[TABLE]
Hence for any ε∈(0,δ(λ)), γ∈(β,β+δ(λ)) and t∈[δ(λ)1,+∞), we have
[TABLE]
Let (M,dβ) be the metric completion of (M,ωβ), which is of finite diameter. Therefore,
[TABLE]
are uniformly bounded from above (see also Proposition 2.4 in [6]). So we prove Theorem 1.5 for γ∈(β,β+δ(λ)). Fix γ0∈(β,β+δ(λ)), we can get Theorem 1.5 for any ε∈(0,1), γ∈(γ0,1) and t∈[1,+∞) by following the arguments in [36]. Combining these two parts, we complete the proof of Theorem 1.5.
4 Proof of the case μβ>0
In this section, we always assume that μβ is positive and there is a conical Kähler-Einstein metric ωφβ(0<β<1) with cone angle 2πβ along D. We first deduce some uniform regularities along the twisted Kähler-Ricci flows (TKRFμγ,εβ), and then prove Lemma 1.8 and Lemma 1.10. For the sake of brevity, we only consider the case λ=1, that is, μγ=γ. Our arguments are also valid for any λ>0, only if the coefficient γ before ωγ(t) in the case of λ=1 is replaced by μγ=1−(1−γ)λ.
Denote ωφβ=ω0+−1∂∂ˉφβ with φβ∈L∞(M)⋂PSH(M,ω0). Assume that Msupφβ⩽−1 and satisfies
[TABLE]
where ξβ is the constant such that V1∫Me−βφβ−F0+ξβ∣s∣h2(1−β)ω0n=1. From Kołodziej’s Lp-estimates [28, 29], φβ is Hölder continuous. By Demailly’s regularization result [15], we approximate φβ with a decreasing sequence of smooth ω0-psh functions φε. Then Dini’s theorem implies that φε converge to φβ in L∞-sense on M. Without loss of generality, we assume that
[TABLE]
for ε∈(0,1]. In the case μβ>0, we normalize φ0 by
[TABLE]
where φ1 comes from the approaching sequence φε with ε=1. Since the twisted Kähler-Ricci flow preserves the Kähler class, we write (TKRFγ,εβ) as the parabolic Monge-Ampère equation on potentials,
where Fγ,εβ=F0+log(ω0n(ωεβ)n⋅(ε2+∣s∣h2)1−β)+(β−γ)φε and ϕγ,εβ(t)=φγ,εβ(t)−kχβ. By the same arguments as in Lemma 3.1 and 3.2, we have
Proposition 4.1**.**
R(ωγ,εβ(t))−(β−γ)trωγ,εβ(t)ωφε−(1−β)trωγ,εβ(t)θε* are uniformly bounded from below by −4n along the twisted Kähler-Ricci flows (TKRFμγ,εβ), that is, for any γ∈[0,1], β∈[0,1], ε>0 and t⩾1,*
[TABLE]
Lemma 4.2**.**
For any T>0, there exists uniform constant C, such that for any t∈[0,T], ε>0 and γ∈[0,1],
[TABLE]
where constant C depends only on ∥φ0∥L∞(M), β, n, ω0 and T.
By using the arguments in section 2 of [37], we get the following uniform Laplacian C2-estimates on M along the twisted Kähler-Ricci flow (TKRFγ,εβ).
Lemma 4.3**.**
For any T>0, there exists constant C depending only on ∥φ0∥L∞(M), n, β, ω0 and T, such that for any t∈(0,T], ε>0 and γ∈[0,1],
[TABLE]
Lemma 4.4**.**
For any T>0, there exists constant C depending only on ∥φ0∥L∞(M), n, β, ω0 and T, such that for any t∈(0,T], ε>0 and γ∈[0,1],
[TABLE]
Beweis.
Since there exists term (β−γ)φε in equation (\refTKRF4), from the proofs of Proposition 3.1 in [36] and Lemma 2.3 in [37], we need only deal with the term
[TABLE]
From [4], there exists a uniform constant A depending on β and ω0 such that
[TABLE]
When γ>β, by (\ref25) and n⩽trωγ,εβ(t)ωεβ⋅trωεβωγ,εβ(t), we have
[TABLE]
When γ⩽β, we have
[TABLE]
Hence we have
[TABLE]
Let
[TABLE]
be the uniformly bounded function introduced by Guenancia-Pa˘un in [21]. Denote functions H1=tlogtrωεβωγ,εβ(t)+tΨερ when γ>β and H2=tlogtrωεβωγ,εβ(t)+tΨερ+t(β−γ)φε when γ⩽β. By choosing suitable B and ρ, and following the arguments in [37], we have
[TABLE]
where constant C depends only on ∥φ0∥L∞(M), n, β, ω0 and T. Then by the arguments as that in the proof of Lemma 2.3 in [37], we get the uniform Laplacian C2-estimates for ωγ,εβ(t).
∎
Hence away from time [math], on any compact subset in M∖D, ωγ,εβ are uniformly equivalent to ω0. Then Evans-Krylov-Safonov’s estimates (see [31]) implies the following proposition.
Proposition 4.5**.**
For any 0<δ<T<∞, k∈N+ and Br(p)⊂⊂M∖D, there exists constant Cβ,δ,T,k,p,r, such that for any ε>0 and γ∈[0,1],
[TABLE]
where constant Cβ,δ,T,k,p,r depends on ∥φ0∥L∞(M), n, β, δ, k, T, ω0 and distω0(Br(p),D).
Straightforward calculation shows that the twisted Ricci potential uγ,εβ(t) with respect to ωγ,εβ(t) at t=21 can be written as
[TABLE]
where Cγ,εβ(21) is a normalization constant such that V1∫Me−uγ,εβ(21)dVγ,εβ(21)=1. By (\ref04), Lemma 4.2 and Lemma 4.3, Cγ,εβ(21) and uγ,εβ(21) are uniformly bounded. Hence Aγ,εβ(21) are uniformly bounded from below for any γ∈(0,1) and ε∈(0,1). Since Aγ,εβ(t) is increasing along (TKRFγ,εβ) when γ∈(0,β], combining this with Jensen’s inequality, we have
Lemma 4.6**.**
There exists uniform constant C, such that
[TABLE]
for any t⩾21, γ∈(0,β] and ε∈(0,1].
We consider the twisted Kähler-Ricci flow (TKRFγ,εβ) starting at t=21. Following the arguments in section 4 of [36], we have the following uniform Perelman’s estimates.
Theorem 4.7**.**
Let ωγ,εβ(t) be a solution of the twisted Kähler Ricci flow (TKRFγ,εβ). Then for any 0<β1<β2⩽β, there exists a uniform constant C, such that
[TABLE]
hold for any γ∈[β1,β2], t≥1 and ε>0.
By using these uniform Perelman’s estimates, we can get the following estimates and convergence for Aγβ(t).
Theorem 4.8**.**
For any γ∈(0,β], there exists uniform constant C, such that
[TABLE]
Furthermore, if Mγβ is bounded form below, then Aγβ(t) converge to [math] as t→+∞.
We denote constant
[TABLE]
where F^{\beta}_{\gamma,\varepsilon}(1)=F_{0}+(\beta-\gamma)\varphi_{\varepsilon}+\log\Big{(}\frac{(\omega^{\beta}_{\gamma,\varepsilon}(1))^{n}(\varepsilon^{2}+|s|_{h}^{2})^{1-\beta}}{\omega_{0}^{n}}\Big{)}. From previous discussions, C~γ,εβ is well-defined and uniformly bounded. Next, we consider the solution ψγ,εβ(t)=φγ,εβ(t)+C~γ,εβeγt to the equation
[TABLE]
By using the same arguments as in the proof of Proposition 4.5 in [37], we have the following two propositions.
Proposition 4.9**.**
For any β0∈(0,β), there exists uniform constant C^β0 such that
[TABLE]
for any ε>0, γ∈[β0,β] and t⩾1.
Proposition 4.10**.**
For any β0∈(0,1), there exists uniform constant C such that
[TABLE]
for any ε>0, γ∈[β0,1) and t⩾1, where ψγ,ε(t) is the solution of equation (\refTKRF6).
Next, we prove the continuity of φγ,εβ(t) with respect to variables γ and ε.
Proposition 4.11**.**
There exists a constant δ^, such that for any t∈(0,δ^), ε∈[0,1) and z∈M, φγ,εβ(t) is increasing with respect to γ∈[0,1].
Beweis.
We first consider the case ε∈(0,1). By Kołodziej’s results [28, 29], there exists a Hölder continuous solution uγ,εβ to the equation
[TABLE]
and uγ,εβ satisfies
[TABLE]
where the normalization constant C^ is uniformly bounded independent of ε and γ, constant C depends only on ∥φ0∥L∞(M), β and F0. We define function
[TABLE]
where
[TABLE]
From similar arguments in the proof of Proposition 3.5 in [37], we know that ψγ,εβ(t) is a subsolution of equation (\refTKRF2) and hence
[TABLE]
for any t∈(0,1), where h1(t) is a continuous function independent of γ and ε such that h(0)=0. Hence there exists δ^, such that h1(t)>−21 for any t∈[0,δ^]. By the normalization (\refnom), we have
[TABLE]
for any γ∈[0,1], ε∈(0,1), t∈(0,δ^) and z∈M. For γ1⩽γ2, on [0,δ^]×M,
[TABLE]
Then by the maximum principle, we have φγ1,εβ(t)⩽φγ2,εβ(t) for any ε∈(0,1), t∈(0,δ^) and z∈M. Then letting ε→0, we get the ε=0 case.
∎
Since φε decrease to φβ as ε↘0, then for fix γ∈[0,β], t∈[0,∞) and z∈M, φγ,εβ(t) is decreasing as ε↘0 (see Proposition 3.3 in [37]). Then by using the same arguments as in section 3, we have the following results.
Proposition 4.12**.**
Let {εi}∈[0,1) and {γi}∈[0,β]. We assume that εi and γi converge to ε∞ and γ∞ respectively. Then for any [δ,T] with 0<δ<T<∞, there exists α∈(0,1) such that φγi,εiβ(t) converge to φγ∞,ε∞β(t) on [δ,T]×M in Cα′-sense for any α′∈(0,α), and on (0,∞)×(M∖D) the convergence is in Cloc∞-sense.
Remark 4.13**.**
From Proposition 4.12, we know that for any [δ,T] with 0<δ<T<∞, the Cα-norm of φγ,εβ(t) on [δ,T]×M for some α∈(0,1) is continuous with respect to γ∈[0,β] and ε∈[0,1). If we fix ε∈(0,1), then the C∞-norm of φγ,εβ(t) on [δ,T]×M is continuous with respect to γ∈[0,β].
By following the arguments as that in Theorem 3.6 and Theorem 3.7, we have the following two theorems.
Theorem 4.14**.**
There exists uniform constant D0β such that
[TABLE]
for any ε∈(0,21) and t⩾1.
Beweis.
From the proof of Theorem 3.6, we need only prove that V1∫Mϕ0,εβ(t)e−F0+Cβ,ε(ε2+∣s∣h2)1−βdV0 is decreasing with respect to t. By Jensen’s inequality and (\ref04), we have
[TABLE]
Then we can get this theorem by following the arguments in Theorem 3.6.
∎
Theorem 4.15**.**
The conical Kähler-Ricci flow (CKRF0β) converges to the conical Kähler-Einstein metric ωφβ in Cloc∞-topology outside divisor D and globally in Cα,β-sense for any α∈(0,min{1,β1−1}).
From the arguments in [35, 36, 60, 61], we have the following Sobolev inequalities along (TKRFγ,εβ) by using Theorem 2.8, Theorem 2.9 and Proposition 4.1.
Theorem 4.16**.**
Let M be a Fano manifold with complex dimension n≥2 and ωγ,εβ(t) be a solution of the twisted Kähler-Ricci flow (TKRFγ,εβ). There exist uniform constants A and B depending only on ∥φ0∥L∞(M), n, β and ω0 such that
[TABLE]
for any v∈W1,2(M,ωγ,εβ(t)), γ∈(0,1], ε>0 and t≥1.
Theorem 4.17**.**
Let M be a Fano manifold with complex dimension 1 and ωγ,εβ(t) be a solution of the twisted Kähler-Ricci flow (TKRFμγ,εβ). For any n0>1, there exist uniform constants A and B depending only on ∥φ0∥L∞(M), n0, β and ω0 such that
[TABLE]
for any v∈W1,2(M,ωγ,εβ(t)), γ∈(0,1], ε>0 and t≥1.
Combining these uniform Sobolev inequalities with Proposition 4.1, we have the following Theorem by following Jiang’s work (Theorem 1.12 in [27]).
Theorem 4.18**.**
Let M be a Fano manifold of complex dimension n and ωγ,εβ(t) be a solution of the twisted Kähler-Ricci flow (TKRFγ,εβ). Let f be a non-negative Lipschitz continuous function on [0,∞)×M satisfying
[TABLE]
on [0,∞)×M in the weak sense, where a⩾0. For any p>0, there exists a constant C depending only on ∥φ0∥L∞(M), β, a, p, ω0 and n0 (n0=n if n⩾2, n0>1 if n=1) such that
[TABLE]
holds for any T<t<T+1 with T⩾1, γ∈(0,1] and ε>0.
Denote L0β=max(Msuptrωβωφβ+oscMφβ,D0β). By using the arguments as that in the proof of Lemma 1.4, we have
Lemma 4.19**.**
There exists a constant δ~>0 such that
[TABLE]
for any ε∈(0,δ~), γ∈(0,δ~) and t∈[δ~1,+∞).
Following the arguments in the proof of Theorem 1.5, we improve the uniform Perelman’s estimates in Theorem 4.7 independent of γ∈(0,β] along (TKRFγ,εβ).
Theorem 4.20**.**
Let ωγ,εβ(t) be a solution of the twisted Kähler Ricci flow (TKRFγ,εβ). There exists a uniform constant C, such that
[TABLE]
hold for any γ∈(0,β], t⩾1 and ε∈(0,δ~), where δ~ is the constant in Lemma 4.19.
From the definitions (\ref9090990) and (\ref9090991), for γ∈(0,β], we have the following inequalities.
[TABLE]
where constant C independent of γ.
Theorem 4.21**.**
Fix a β0∈(0,δ~) obtained in Lemma 4.19, there exists a constant Cβ0 such that
[TABLE]
for any ε∈(0,δ~) and t∈[0,∞).
Proof of Lemma 1.8. We denote A=max(∥φβ∥C0(M)+β0C^β0+∣ξβ∣,Cβ0). If the lemma is not true. For δ1=min(1,δ~), there are ε1∈(0,δ1), γ1′∈(β0,β) and t1′∈[δ11,∞), such that
[TABLE]
Assume that t1′∈[1,T1], we have
[TABLE]
Combining Remark 4.13 with (\ref52), there exists γ1∈(β0,γ1′), such that
[TABLE]
Then there exists t1∈[1,T1] such that
[TABLE]
For δ2=min(21,T1+11,ε1), there exist ε2∈(0,δ2), γ2′∈(β0,β) and t2′∈[δ21,∞), such that
[TABLE]
Assume t2′∈[T1+1,T2], then we have
[TABLE]
Combining Remark 4.13 with (\ref52) again, there exists γ2∈(β0,γ2′), such that
[TABLE]
and then there exists t2∈[T1+1,T2] such that
[TABLE]
After repeating above process, we get a subsequence ψγi,εiβ(ti) with εi↘0, γi∈(β0,β), ti∈[Ti−1+1,Ti] and ti↗∞ satisfying
[TABLE]
For any t∈[Ti−1,Ti−1+1], we assume the maximum (or minimun) point of ψγi,εiβ(t) on M is z1 (or z2), then by Proposition 4.9 and (\ref58),
[TABLE]
where constant C independent of γi, εi and t∈[Ti−1,Ti−1+1]. On the other hand, we can write equation (\refTKRF5) as
[TABLE]
We integrate above equality on both sides, there exists a uniform constant C such that
[TABLE]
for any γ∈[β0,β], ε∈(0,1) and t⩾1. Then by (\ref59), we have
[TABLE]
for any t∈[Ti−1,Ti−1+1], γi and εi. Hence there exists uniform constant C such that
[TABLE]
for any γi and εi. By Lemma 4.4 and Proposition 4.9, there exists constant C such that
[TABLE]
Then for any γi and εi, at t=Ti−1+41,
[TABLE]
Then by Proposition 3.1 in [36], (\ref62) and Proposition 4.9, on [Ti−1+41,Ti]×M, we have
[TABLE]
By Evans-Krylov-Safonov’s estimates, for any Br(p)⊂⊂M∖D, there is uniform constant Ck,p,r such that
[TABLE]
for any t∈[Ti−1+21,Ti], γi and εi. Hence, for any K⊂⊂M∖D, we have
[TABLE]
for any i and k∈N+. Then ψγi,εiβ(ti) (by taking a subsequence if necessary) converge to a function ψγ∞β∈C0(M)⋂C∞(M∖D).
Let uγ∞β be the twisted Ricci potential of ωγ∞β=ω0+−1∂∂ˉψγ∞β. The Lebesgue Dominated Convergence theorem implies that V1∫Me−uγ∞βdVγ∞β=1. Since Aγ,εβ(t) is increasing along the flow (TKRFγ,εβ), for any j<i,
[TABLE]
the second inequality due to Jensen’s inequality. Let i→∞, we have
[TABLE]
Since Mγ∞β is bounded from below (see (\ref20190213133)), by Theorem 4.8, we obtain
[TABLE]
after letting j→∞. Since function log is strictly concave, we conclude uγ∞β=0 by using Jensen’s inequality and the normalization of uγ∞β. This means that ωγ∞β is a twisted conical Kähler-Einstein metric with cone angle 2πβ along D and satisfies
[TABLE]
At the same time, we also have
[TABLE]
Both ψγ∞β and φβ are bounded (in fact, they are Hölder continuous). Berndtsson’s uniqueness theorem [2] implies that
[TABLE]
where F∈Aut(M) is generated by a holomorphic vector X on M. Since (β−γ∞)ωφβ has zero Lelong number, then by Siu’s decomposition for a positive closed current, we have
[TABLE]
which implies that X is tangential to D. Then f=id because we assume that there is no nontrivial holomorphic vector fields tangent to D. Hence ωγ∞β=ωφβ, and then ψγ∞β=φβ+C1. On the other hand, we have
[TABLE]
Let ψ˙γi,εiβ(ti)=uγi,εiβ(ti)+cγi,εiβ(ti), where constants cγi,εiβ(ti) are uniformly bounded and hence converge to a constant C2 (by taking a subsequence if necessary). Since uγi,εiβ(ti) converge to [math] in Cloc∞-topology in M∖D, ψ˙γi,εiβ(ti) converge to C2 in Cloc∞-topology in M∖D. Letting i→∞ in above equation, we have
[TABLE]
Equation (\ref2019022301) implies that C1=γ∞C2−ξβ. From Proposition 4.9, we conclude that ∣C1∣⩽β0C^β0+∣ξβ∣. Letting i→∞ in (\ref58), we have
[TABLE]
This leads to a contradiction. Thus Lemma 1.8 is proved.
By using Lemma 1.8 and Remark 4.13, we get the uniform C0-estimates for ψβ,εβ(t)=ψβ,ε(t).
Proof of Lemma 1.10. We only prove that there exists δ>0 such that
[TABLE]
for any ε∈(0,δ), γ∈[β,β+δ) and t∈[δ1,+∞), where ξβ is the constant in (\ref2019022301), Bβ is the constant in (\ref731) and Cβ comes from Proposition 4.10. The other direction is similar.
Denote L=max(∥φβ∥C0(M)+βCβ+∣ξβ∣,Bβ). If this lemma is not true. For δ1=min(1,δβ0), there exist ε1∈(0,δ1), γ1′∈(β,β+δ1) and t1′∈[δ11,∞), such that
[TABLE]
Assume t1′∈[1,T1], then we have
[TABLE]
Combining Remark 3.10 with (\ref731), there exists γ1∈(β,γ1′), such that
[TABLE]
Then there exists t1∈[1,T1] such that
[TABLE]
For δ2=min(21,T1+11,ε1,γ1−β), there exist ε2∈(0,δ2), γ2′∈(β,β+δ2) and t2′∈[δ21,∞), such that
[TABLE]
Assume t2′∈[T1+1,T2], then we have
[TABLE]
Combining Remark 3.10 with (\ref731) again, there exists γ2∈(β,γ2′), such that
[TABLE]
and then there exists t2∈[T1+1,T2] such that
[TABLE]
After repeating above process, we get a subsequence ψγi,εi(ti) with εi↘0, γi↘β, ti∈[Ti−1+1,Ti] and ti↗∞ satisfying
[TABLE]
By the similar arguments as in the proof of Lemma 1.8, we conclude that there exists uniform constants C independent of εi and γi, such that
[TABLE]
The Evans-Krylov-Safonov’s estimates imply that for any K⊂⊂M∖D and k∈N+, there exists uniform constant Ck,K such that for any γi, εi and t∈[Ti−1+43,Ti],
[TABLE]
Then we can conclude that ψγi,εi(ti) (by taking a subsequence if necessary) converge to a function ψβ∈C0(M)⋂C∞(M∖D).
Let uβ be the twisted Ricci potential of ωψβ=ω0+−1∂∂ˉψβ, then uβ satisfies V1∫Me−uβdVψβ=1. Since Aγ,ε(t) is increasing along the flow (TKRFγ,ε), for any j<i,
[TABLE]
the second inequality due to Jensen’s inequality. Let i→∞, we have
[TABLE]
Since the Log Mabuchi energy Mβ is bounded from below, by Theorem 2.14, we obtain
[TABLE]
after letting j→∞. Since log is strictly concave, we conclude uβ=0 by using Jensen’s inequality and its normalization. This means that ωψβ is a conical Kähler-Einstein metric with cone angle 2πβ along D. Since both ψβ and φβ are bounded (in fact, they are Hölder continuous), Berndtsson’s uniqueness theorem [2] implies that
ωψβ=ωφβ, and then ψβ=φβ+C1. On the other hand, we have
[TABLE]
Let ψ˙γi,εi(ti)=uγi,εi(ti)+cγi,εi(ti), where constants cγi,εi(ti) are uniformly bounded and hence converge to a constant C2 (by taking a subsequence if necessary). Since uγi,εi(ti) converge to [math] in Cloc∞-topology in M∖D, ψ˙γi,εi(ti) converge to C2 in Cloc∞-topology in M∖D. Letting i→∞ in (\ref1922001111), we have
[TABLE]
Equation (\ref2019022301) implies that C1=βC2−ξβ. From Proposition 4.10, we conclude that ∣C1∣⩽βCβ+∣ξβ∣. Hence the following inequalities are deduced after we let i→∞ in (\ref82).
[TABLE]
This leads to a contradiction. Thus Lemma 1.10 is proved.
Fix a γ∈(β−δ,β+δ) obtained in Lemma 1.10, combining Proposition 4.10 with Proposition 3.1 in [36], we know that there exists uniform constant C depending only on ∥φ0∥L∞(M), n, β and ω0 such that
[TABLE]
for any ε∈(0,δ). Then for k∈N+ and K⊂⊂M∖D, there exists constant Ck,K depending only on ∥φ0∥L∞(M), n, β, k, ω0 and distω0(K,D), such that for ε∈(0,δ) and t⩾1, we have
[TABLE]
At the same time, the twisted Mabuchi energy Mγ,ε are uniformly bounded from below along the twisted Kähler-Ricci flow (TKRFγ,ε), that is, there exists uniform constant C such that
[TABLE]
for any ε∈(0,δ) and t⩾1. Then by using the arguments in [36, 37], we can prove that the conical Kähler-Ricci flow (CKRFγ) converges to a conical Kähler-Einstein metric with cone angle 2πγ along D in Cloc∞-topology outside D and globally in Cα,γ-sense for any α∈(0,min{1,γ1−1}).
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