Resolving the Bethe–Salpeter Kernel

A novel method for constructing a kernel for the meson bound-state problem is described.It produces a closed form that is symmetry-consistent(discrete and continuous)with the gap equation defined by any admissible gluon-quark vertex,Γ.Applicable even when the diagrammatic content ofΓis unknown,the scheme can foster new synergies between continuum and lattice approaches to strong interactions.The framework is illustrated by showing that the presence of a dressed-quark anomalous magnetic moment inΓ,an emergent feature of strong interactions,can remedy many defects of widely used meson bound-state kernels,including the mass splittings between vector and axial-vector mesons and the level ordering of pseudoscalar and vector meson radial excitations.

Impressions of the Continuum Bound State Problem in QCD

Modern and anticipated facilities will deliver data that promises to reveal the innermost workings of quantum chromodynamics(QCD).In order to fulfill that promise,phenomenology and theory must reach a new level,limiting and overcoming model-dependence,so that clean lines can be drawn to connect the data with QCD itself.Progress in that direction,made using continuum methods for the hadron bound-state problem,is sketched herein.

Chiral symmetry restoration and properties of Goldstone bosons at finite temperature

We study chiral symmetry restoration by analyzing thermal properties of QCD's(pseudo-)Goldstone bo-sons,especially the pion.The meson properties are obtained from the spectral densities of mesonic imaginary-time correlation functions.To obtain the correlation functions,we solve the Dyson-Schwinger equations and the inhomo-geneous Bethe-Salpeter equations in the leading symmetry-preserving rainbow-ladder approximation.In chiral limit,the pion and its partner sigma degenerate at the critical temperature T_(c).At T≥T_(c),it was found that the pion rapidly dissociates,which signals deconfinement phase transition.Beyond the chiral limit,the pion dissociation temperature can be used to define the pseudo-critical temperature of the chiral phase crossover,which is consistent with that ob-tained by the maximum point of chiral susceptibility.A parallel analysis for kaon and pseudoscalar ss suggests that heavymesons maysurviveabove T_(c).

Mass spectra and wave functions of the doubly heavy baryons with J^P=1^+ heavy diquark cores

Mass spectra and wave functions of the doubly heavy baryons are computed assuming that the two heavy quarks inside a baryon form a compact heavy'diquark core'in a color anti-triplet,and bind with the remaining light quark into a colorless baryon.The two reduced two-body problems are described by the relativistic Bethe-Salpeter equations(BSEs)with the relevant QCD inspired kernels.We focus on the doubly heavy baryons with 1^+heavy diquark cores.After solving BSEs in the instantaneous approximation,we present the mass spectra and the relativistic wave functions of the diquark cores,and of the low-lying baryon states J^P=(1/2)^+and(3/2)^+with flavors(ccq)(bcq)and(bbq).A comparison with other approaches is also made.