Mapping chiral symmetry breaking in the excited baryon spectrum

Abstract

We study the conjectured "insensitivity to chiral symmetry breaking" in the highly excited light baryon spectrum. While the experimental spectrum is being measured at JLab and CBELSA/TAPS, this insensitivity remains to be computed theoretically in detail. As the only existing option to have both confinement, highly excited states, and chiral symmetry, we adopt the truncated Coulomb-gauge formulation of QCD, considering a linearly confining Coulomb term. Adopting a systematic and numerically intensive variational treatment up to 12 harmonic oscillator shells we are able to access several angular and radial excitations. We compute both the excited spectra of I ¼ 1=2 and I ¼ 3=2 baryons, up to large spin J ¼ 13=2, and study in detail the proposed chiral multiplets. While the static-light and light-light spectra clearly show chiral symmetry restoration high in the spectrum, the realization of chiral symmetry is more complicated in the baryon spectrum than earlier expected.

Tetraquark resonances computed with static lattice QCD potentials and scattering theory

“…A stable udbb tetraquark with quantum numbers I(J P ) = 0(1 + ) has been predicted [1][2][3][4][5][6][7][8][9] and been confirmed by similar computations using four quarks of finite mass [10]. Here we extend our investigation by including a new technique from scattering theory, the emergent wave method [11], and search for possibly existing tetraquark resonances (cf. also [12] for more details).…”

Color field densities of the quark-antiquark excited flux tubes in SU(3) lattice QCD

“…For instance in quantum mechanics, when using a limited basis of states as a variational set to compute the energy of excited states in a spectrum, a rule of thumb is to trust only circa the lowest half of the spectrum (in Ref. [25], among 11 to 12 states, only the lightest 6 are trusted). Just to illustrate why we must exclude the remaining states, in Fig.…”

Including heavy spin effects in the prediction of a b¯b¯ud tetraquark with lattice QCD potentials

“…e.g. [2][3][4][5][6][7][8][9][10][11]). Also experimentally this is a difficult problem, since exotic candidates are typically resonances immersed in the excited hadron spectra, which quickly decay to several non-exotic hadrons.…”