Analysis of the heavy quarkonium states $h_c$ and $h_b$ with QCD sum rules

TL;DR

This paper uses QCD sum rules with tensor currents to analyze the masses and decay constants of P-wave spin-singlet heavy quarkonium states $h_c$ and $h_b$, finding results consistent with experimental data.

Contribution

It introduces the use of tensor currents $ar{Q}\sigma_{\mu u}Q$ to study heavy quarkonium states and calculates their properties with comprehensive QCD sum rule techniques.

Findings

Masses are consistent with experimental data.

Decay constants are obtained and can be used as inputs for further studies.

Analytical spectral densities are derived for decay process applications.

Abstract

In this article, we take the tensor currents $\bar{Q}(x)\sigma_{\mu\nu}Q(x)$ to interpolate the $P$-wave spin-singlet heavy quarkonium states $h_Q$, and study the masses and decay constants with the Borel sum rules and moments sum rules. The masses and decay constants from the Borel sum rules and moments sum rules are consistent with each other, the masses are also consistent with the experimental data. We can take the decay constants as basic input parameters and study other phenomenological quantities with the three-point correlation functions via the QCD sum rules. The heavy quarkonium states $h_Q$ couple potentially to the tensor currents $\bar{Q}(x)\sigma_{\mu\nu}Q(x)$, and have the quark structure $\epsilon^{ijk}\xi^{\dagger}\sigma^k\zeta$ besides the quark structure $ik_2^i \xi^{\dagger}\sigma \cdot (\vec{k}_1-\vec{k}_2)\zeta $. In calculations, we take into account the leading-order, next-to-leading-order perturbative contributions, and the gluon condensate, four-quark condensate contributions in the operator product expansion. The analytical expressions of the perturbative QCD spectral densities have applications in studying the two-body decays of a boson to two fermions with the vertexes $\sigma_{\mu\nu}\gamma_5$ and $\sigma_{\mu\nu}$.