Hadronic decay properties of newly observed $\Omega_c$ baryons
Ze Zhao, Dan-Dan Ye, Ailin Zhang

TL;DR
This paper calculates the hadronic decay widths of newly observed $\\Omega_c$ baryons using a $^3P_0$ model, providing possible quantum state assignments consistent with experimental decay widths.
Contribution
It offers the first detailed decay width calculations for these states, suggesting specific quantum number assignments based on decay features and experimental data.
Findings
$\\Omega_c(3066)^0$ and $\Omega_c(3090)^0$ are likely $1P$-wave states.
$\\Omega_c(3000)^0$, $\\Omega_c(3050)^0$, and $\\Omega_c(3119)^0$ favor $1D$-wave state assignments.
Predicted decay widths align with experimental measurements for these assignments.
Abstract
Hadronic decay widths of the newly observed charmed strange baryons, , , , and have been calculated in a model. Our results indicate that and can be interpreted as the wave or . Though the measured masses of , and are lower than existed theoretical predictions of wave , the hadronic decay features of these favor assignments of the wave states. is possibly or , is possibly or , and is possibly ,…
| Assignments | |||||||
|---|---|---|---|---|---|---|---|
| 0 | 0 | 1 | 1 | 1 | |||
| , | 1 | 0 | 1 | 1 | 1 | ||
| , | 2 | 0 | 1 | 1 | 1 | ||
| , | 1 | 1 | 0 | 1 | 0 | ||
| , | 1 | 0 | 2 | 2 | 1 | ||
| , | 2 | 0 | 2 | 2 | 1 | ||
| , | 3 | 0 | 2 | 2 | 1 | ||
| , | 1 | 2 | 0 | 2 | 1 | ||
| , | 2 | 2 | 0 | 2 | 1 | ||
| , | 3 | 2 | 0 | 2 | 1 | ||
| 0 | 1 | 1 | 0 | 0 | |||
| , | 1 | 1 | 1 | 1 | 0 | ||
| , | 1 | 1 | 1 | 1 | 0 |
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.3 | 0.2 | 0.5 | ||
| 0.3 | 0.2 | 0.5 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 2.8 | 2.2 | 5.0 | ||
| 2.8 | 2.2 | 5.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 25.7 | 19.4 | 45.1 | ||
| 25.7 | 19.4 | 45.1 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 |
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 2.9 | 2.4 | 5.3 | ||
| 2.9 | 2.4 | 5.3 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 10.0 | 8.9 | 18.9 | ||
| 10.0 | 8.9 | 18.9 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 89.4 | 80.4 | 168.8 | ||
| 89.4 | 80.4 | 168.8 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.1 | 0.1 | 0.2 | ||
| 0.1 | 0.1 | 0.2 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 |
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 4.6 | 3.9 | 8.5 | ||
| 4.6 | 3.9 | 8.5 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 12.8 | 11.7 | 24.5 | ||
| 12.8 | 11.7 | 24.5 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.3 | 0.2 | 0.5 | ||
| 0.3 | 0.2 | 0.5 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 |
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | |||||
| 8.0 | 7.0 | 15.1 | ||||
| 8.0 | 7.0 | 15.1 | ||||
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | 0.2 | 0.1 | 0.3 | ||
| 17.4 | 16.3 | 0.4 | 0.2 | 34.3 | ||
| 17.4 | 16.3 | 0.1 | 0.1 | 33.9 | ||
| 0.0 | 0.0 | 0.9 | 0.5 | 1.4 | ||
| 0.0 | 0.0 | |||||
| 0.1 | ||||||
| 0.1 | ||||||
| 3.4 | 2.0 | |||||
| 0.8 | 0.5 | |||||
| 0.0 | 0.0 | 7.6 | 4.6 | 12.6 | ||
| 0.0 | 0.0 | |||||
| 0.6 | 0.5 | 1.0 | ||||
| 0.6 | 0.5 | 1.0 | ||||
| 0.0 | 0.0 | 6.7 | 4.1 | 10.8 | ||
| 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 3.4 | 2.0 | 5.4 | ||
| 0.0 | 0.0 |
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | 0.2 | 0.2 | 0.5 | ||
| 13.9 | 12.5 | 0.4 | 0.4 | 27.3 | ||
| 13.9 | 12.5 | 0.2 | 0.2 | 26.8 | ||
| 0.0 | 0.0 | |||||
| 0.0 | 0.0 | 1.6 | 1.2 | 2.8 | ||
| 23.5 | 22.2 | 1.4 | 1.2 | 48.3 | ||
| 23.4 | 22.2 | 0.4 | 0.3 | 46.3 | ||
| 0.0 | 0.0 | 3.2 | 2.6 | 5.8 | ||
| 0.0 | 0.0 | |||||
| 0.1 | 0.1 | 0.2 | ||||
| 0.1 | 0.1 | 0.2 | ||||
| 12.6 | 10.6 | |||||
| 3.2 | 2.6 | |||||
| 0.0 | 0.0 | 28.5 | 23.7 | 52.3 | ||
| 0.0 | 0.0 | |||||
| 1.2 | 1.1 | 2.3 | ||||
| 1.2 | 1.1 | 2.3 | ||||
| 0.0 | 0.0 | 25.2 | 21.0 | 46.2 | ||
| 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||
| 0.0 | 0.0 | 12.7 | 10.6 | 23.2 | ||
| 0.0 | 0.0 |
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Hadronic decay properties of newly observed baryons
Ze Zhao
Department of Physics, Shanghai University, Shanghai 200444, China
Dan-Dan Ye
Department of Physics, Shanghai University, Shanghai 200444, China
College of Mathematics, Physics and Information Engineering, Jiaxing University, Jiaxing 314001, China
Ailin Zhang
Department of Physics, Shanghai University, Shanghai 200444, China
Abstract
Hadronic decay widths of the newly observed charmed strange baryons, , , , and have been calculated in a model. Our results indicate that and can be interpreted as the wave or . Though the measured masses of , and are lower than existed theoretical predictions of wave , the hadronic decay features of these favor assignments of the wave states. is possibly or , is possibly or , and is possibly , , or . The predicted total decay widths in these assignments are consistent with experiment.
pacs:
13.30.Eg, 14.20.Lq, 12.39.Jh
I Introduction
Very recently, five narrow excited baryons were reported by the LHCb collaboration LHCb1 . Their masses and decay widths were measured in as follows,
[TABLE]
[TABLE]
[TABLE]
[TABLE]
[TABLE]
The quantum numbers of these five baryons have not been measured.
According to Particle Data Group pdg2016 , two baryons have been observed: the ground state and (also known as ) with and , respectively. No other baryon has been reported before the LHCb experiment.
Theoretical predictions of the spectra of orbitally excited baryons have been conducted in many different models Capstick:2809 (1986) ; Ebert2011 ; Roberts2008 ; Gar2007 ; Yoshida ; Shah . Relevant references can be found in reviews Capstick:S241 (2000) ; klempt ; roberts and references therein. From the spectra, these newly observed baryons are most possibly the orbitally excited or the radially excited states. Theoretical predicted masses of the orbitally excited baryons are MeV higher than the observed ones.
Since the report of LHCb, the spectra of orbitally excited baryons have been explored in Refs. Agaev2017 ; Marek2017 ; Padm ; wwang . The hadronic decays of these baryons have also been studied through QCD sum rules, chiral quark model or other models in Refs. CHX2017 ; Marek2017 ; Zhong2017 ; CHY2017 ; wwang . In these explorations, the observed baryons were interpreted as the or , while the possibility has not been explored for their lower masses. However, the mass prediction may be largely different in different models. As indicated in Ref. chen , the mass prediction of the excited and baryons in Ref. Capstick:2809 (1986) were really largely different from the results in Ref. Ebert2011 . The study of possibility of these through their hadronic decays is necessary.
For the understanding of these excited baryons, it is useful to explore their hadronic decays in different model for a cross-check. model is a phenomenological method to study the OZI-allowed hadronic decays of hadrons. In addition to mesons, it is employed successfully to explain the hadronic decays of baryons yaouanc1 ; Capstick:2809 (1986) ; Roberts:171 (1992) ; Capstick:1994 (1993) ; Capstick:4507 (1994) ; Capstick:S241 (2000) ; Chong:094017 (2007) . In this paper, model will be employed to study the hadronic decays of , , , and . In particular, the possibility of these will be examined in detail.
This work is organized as follows. In Sec.II, we give a brief review of the model. In Sec.III, we present our numerical results. We give our conclusions and discussions in Sec.IV.
II Baryon decay in the model
Proposed by Micumicu1969 and later developed by Yaouanc et al yaouanc1 ; yaouanc2 ; yaouanc3 , model is also known as a Quark Pair Creation (QPC) model. It assumes that a pair of quark is created from the vacuum with , and then the created quarks regroup with the quarks from the initial hadron A to form two daughter hadrons B and C. The process of a baryon decay is shown in Fig. I.
In the model, the hadronic decay width of a process is as follows yaouanc3 ,
[TABLE]
where and are the mass and total angular momentum of the initial baryon A, respectively. and are the masses of the final hadrons. is the helicity amplitude, which reads Chong:094017 (2007)
[TABLE]
The space integral follows as 114020
[TABLE]
Simple harmonic oscillator (SHO) wave functions are employed as the baryon wave functionsCapstick:2809 (1986) ; Capstick:1994 (1993) ; Capstick:4507 (1994) . For practical calculations such as the flavor matrix and the space integrals in the model, more details were presented in Refs.Capstick:1994 (1993) ; yaouanc3 ; Chong:094017 (2007) ; 114020 .
Two parameters, the in SHO and the quark pair creation strength , are adopted as those in Refs. Chong:094017 (2007) ; Blundell:3700 (1996) ; 114020 . , and MeV for meson . For baryons, a universal value MeV is employed. The masses of , , , and are taken as MeV, MeV, MeV, MeV and MeV, respectively. Masses of K mesons and baryons are taken from PDG pdg2016 .
The quantum numbers of the P-wave and D-wave baryons are complicated CHX2015 ; CHX2016 , and we follow the notations in Ref. Chong:094017 (2007) . The quantum numbers involved in the calculations are listed in Table 1. In the table, denotes the orbital angular momentum between the two light quarks, denotes the orbital angular momentum between the charm quark and the two light quark system, is the total orbital angular momentum of and . denotes the total spin of the two light quarks, is total angular momentum of and . is the total angular momentum of the baryons. The hat and the check are also used to denote the assignments with and , respectively. The superscript is adopted to denote the different total orbital angular momentum in .
III Numerical results
In the model, , and could be created from the vacuum. However, there exists no experimental signal for the decay mode with a creation. Once the measured masses of baryons and the mass threshold of the final particles, and , have been taken into account, there are two decay channels for , and . For and , and are also allowed. Possible decay modes and corresponding hadronic decay widths of these baryons in different wave and wave assignments have been computed and presented in from Table 2 to Table 6. The vanish modes in these five tables indicate forbidden channels.
All the five new baryons were observed in the channel. The decay width of is MeV. From the results in Table 2, the most possible assignment of is or . In these two assignments, the total decay widths are the same MeV, which is very close to the experimental data.
The experimental measured decay width of is extremely narrow, which is smaller than MeV. From Table 3, the possible assignment of is or . The theoretical prediction of the decay width is MeV.
For , the measured decay width is . From Table 4, the total decay widths of and are the same MeV, which is a little larger than the experimental result. Under the theoretical uncertainty, these assignments are possible for .
For and , the channels and open. In Table 5 and Table 6, many channels decaying to and are forbidden while to and are not. In particular, the total decay widths of and in some assignments are extremely large. In comparison with experiment, the possible assignment for is or , and four wave assignments are possible for : , , and . In these assignments, the decay widths to and channels are very tiny and could be neglected.
IV Conclusions and discussions
In this work, we study the hadronic decays of five newly observed baryons , , , and in the model. In different assignments of wave and wave , hadronic decay widths of these baryons have been calculated. In comparison with experiment, possible assignments of these have been made.
All the five baryons were observed in the channel with very narrow decay widths. Our results indicates that these could be wave or wave baryons. is possibly wave or . is possibly wave or . is possibly wave or . The possible assignment for is wave or , and four wave assignments , , and are possible for . The predicted decay widths are consistent with experimental data.
In experiment, only were observed, which may not provide enough information on their identification. Furthermore, resonance with the same numbers and similar masses may mix with each other, which may make it difficult to distinguish them. As for wave , the channels and is hardly to be observed for the tiny decay widths. More information on these baryons are expected to be given in forthcoming experiment.
Acknowledgements.
This work is supported by National Natural Science Foundation of China under the grants: 11475111 and 11075102.
The reference list from the paper itself. Each links out to its DOI / PubMed record.
- 1(1) R. Aaij et al. [LH Cb Collaboration], ar Xiv:1703.04639 [hep-ex].
- 2(2) C. Patrignani et al. [Particle Data Group], Chin. Phys. C 40 , 100001 (2016).
- 3(3) S. Capstick and N. Isgur, Phys. Rev. D 34 , 2809 (1986).
- 4(4) D. Ebert, R. N. Faustov, and V. O. Galkin, Phys. Rev. D 84 , 014025 (2011).
- 5(5) W. Roberts and M. Pervin, Int. J. Mod. Phys. A 23 , 2817 (2008).
- 6(6) H. Garcilazo, J. Vijande, and A. Valcarce, J. Phys. G 34 (2007) 961.
- 7(7) T. Yoshida, E. Hiyama, A. Hosaka, M. Oka and K. Sadato, Phys. Rev. D 92 , 114029 (2015).
- 8(8) Z. Shah, K. Thakkar, A. K. Rai and P. C. Vinodkumar, Chin. Phys. C 40 , 123102 (2016).
