Nuclear Theory·nucl-th

Friday·April 2, 2021

6 papers—4 primary·2 cross-listed

05
[Submitted on 31 Mar 2021] (cross-list from hep-ph)
Spinning Gluons from the QCD Light-Ray OPE
Hao Chen🇨🇳 · Ian Moult🇺🇸 · Hua Xing Zhu🇨🇳
We study the transverse spin structure of the squeezed limit of the three-point energy correlator, $⟨ E (n_{1}) E (n_{2}) E (n_{3})⟩$ . To describe its all orders perturbative behavior, we develop the light-ray operator product expansion (OPE) in QCD. At leading twist the iterated OPE of $E (n_{i})$ operators closes onto light-ray operators $O^{[J]} (n)$ with spin $J$ , and transverse spin $j = 0, 2$ . We compute the $E (n_{1}) E (n_{2})$ , $E (n_{1}) O^{[J]} (n_{2})$ and $O^{[J_{1}]} (n_{1}) O^{[J_{2}]} (n_{2})$ OPEs as analytic functions of $J$ , which allows for the description of arbitrary squeezed limits of $N$ -point correlators in QCD. We use these results with $J = 3$ to reproduce the perturbative expansion in the squeezed limit of the three-point correlator, as well as to resum the leading twist singular structure for both quark and gluon jets, including transverse spin contributions, as required for phenomenological applications. Finally, we briefly comment on the transverse spin structure at higher twists, and show that to all orders in the twist expansion the highest transverse spin contributions are universal between quark and gluon jets, and are descendants of the leading twist transverse spin-2 operator, allowing their resummation into a simple two-dimensional Euclidean conformal block. Due to the general applicability of our results to arbitrary correlation functions of energy flow operators, we anticipate that they can be widely applied to improving our understanding of jet substructure at the LHC.
Comments:
38 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2104.00009 [pdf]
JHEP(2022)·84 citations
06
[Submitted on 1 Apr 2021] (cross-list from hep-ph)
Neutral and charged mesons in magnetic fields: A resonance gas in a non-relativistic quark model
Toru Kojo🇨🇳
We analyze mesons in constant magnetic fields ( $B$ ) within a non-relativistic constituent quark model. Our quark model contains a harmonic oscillator type confining potential, and we perturbatively treat short range correlations to account for the spin-flavor energy splittings. We study both neutral and charged mesons taking into account the internal quark dynamics. The neutral states are labelled by two-dimensional momenta for magnetic translations, while the charged states by two discrete indices related to angular momenta. For $B ≪ Λ_{QCD}^{2}$ ( $Λ_{QCD} \sim 200$ MeV: the QCD scale), the analyses proceed as in usual quark models, while special precautions are needed for strong fields, $B \sim Λ_{QC D}^{2}$ , especially when we treat short range correlations such as the Fermi-Breit-Pauli interactions. We compute the energy spectra of mesons up to energies of $\sim 2.5$ GeV and use them to construct the meson resonance gas. Within the assumption that the constituent quark masses are insensitive to magnetic fields, the phase space enhancement for mesons significantly increases the entropy, assisting a transition from a hadron gas to a quark gluon plasma. We confront our results with the lattice data, finding reasonable agreement for the low-lying spectra and the entropy density at low temperature less than $\sim 100$ MeV, but our results at higher energy scale suffer from artifacts of our confining potential and non-relativistic treatments.
Comments:
14 pages, 9 figures; A contribution to the topical issue "The QCD Phase Diagram in Strong Magnetic Fields"; v2 revised, 18 pages, 10 figures, comparisons with the lattice results were added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2104.00376 [pdf]
EPJA(2021)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE

Spinning Gluons from the QCD Light-Ray OPE

Neutral and charged mesons in magnetic fields: A resonance gas in a non-relativistic quark model

Affiliations