Next-to-leading order QCD corrections to electromagnetic production and decay of fully charm tetraquarks

TL;DR

This work analyzes the electromagnetic interactions of fully charm tetraquarks within the NRQCD framework, focusing on two-photon decays and production via gamma gamma fusion in ultra-peripheral collisions and e+e- collisions. It derives the NRQCD factorization formulas for T4c -> gamma gamma, computes next-to-leading order QCD corrections to the short-distance coefficients, and applies crossing symmetry to obtain photoproduction cross sections. Numerical results reveal sizable NLO effects for the 0++ state and more modest corrections for the 2++ state, with cross sections in UPCs and e+e- processes potentially accessible at current or planned facilities, depending on the nonperturbative LDME inputs. The study highlights the feasibility of using electromagnetic channels to probe the internal structure of fully charm tetraquarks and to constrain their nonperturbative matrix elements.

Abstract

We investigate the electromagnetic properties of the fully charm tetraquark states, particularly incorporating contributions from internal gluon radiations. The paper first presents analytical expressions for the next-to-leading-order (NLO) QCD corrections to the decay amplitudes of fully charm tetraquarks into two photons. It is found that the QCD corrections are significant for the $J^{PC}=0^{++}$ fully charm tetraquark decay process, whereas they are relatively small for the $J^{PC}=2^{++}$ fully charm tetraquark decay process. Subsequently, by considering photon-photon fusion in ultra-peripheral high-energy collisions of protons and nuclei and in electron-positron collision processes, we provide theoretical predictions for the production cross sections of fully-charm tetraquark states. The results presented in this work regarding the electromagnetic production and decay of fully charm tetraquarks shall be tested in current and future experiments.

Figures (2)

• Figure 1: Typical one-loop Feynman diagrams for the $T_{4c}\rightarrow \gamma\gamma$. The thick black lines stand for the massive charm quarks.
• Figure 2: The decay widths of $T^{0++}_{4c}\rightarrow\gamma\gamma$ and $T^{2++}_{4c}\rightarrow\gamma\gamma$ with different models of LDMEs for fully charm tetraquarks. The error bars denote the scale uncertainties.