Axial charges of the hidden-charm pentaquark states

Abstract

With the chiral quark model, we have calculated the axial charges of the pentaquark states with (I, I 3 ) = ( 1 2 , 1 2 ) and J P = 1 2 ± , 3 2 ± , and 5 2 ± . The P c states with the same J P quantum numbers but different color-spinflavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the J P = 3 2 ± or 5 2 ± pentaquark states, their axial charges are much smaller than that of the proton.PACS numbers: 14.20.Lq, 12.39.Fe 2 ± , 3 2 ± , 5 2 ± , and 7 2 + in the molecular model, the diquark-triquark model, and the diquark-diquark-antiquark model, respectively. In fact, different color-flavor structures lead to very different magnetic moments of the hidden-charm pentaquarks. In other words, the magnetic moments may be a useful tool to distinguish various models. The axial charge of the baryon state is also a fundamental observable. The axial charge of the nucleon was measured in the beta decay of the polarized neutrons [48,49]. The axial charge of the P c states can also be measured from their semileptonic decays in the future. Moreover, since the width of the P c (4380) state is quite large, its axial charge may be directly extracted from the process P c → P c + π → J/ψ + p + π once the P c (4380) state is produced.The mass and magnetic moment of the hidden-charm pentaquark state depend on both the light and the heavy quarks. In contrast, the axial charge of the P c state is very sensitive to the color, spin, and isospin configurations of the light quarks inside the pentaquarks. Consequently, the axial charges provide a new independent probe of the inner structures of the P c states.The chiral symmetry and its spontaneous breaking play a pivotal role in the low-energy regime, which inspired various versions of the chiral quark model [50][51][52][53][54]. The long-range one-pion-exchange force is introduced to model the interaction between the light quarks, together with the confinement and the one-gluon-exchange potential [55][56][57][58][59]. The chiral quark models are widely * Electronic address: wgj@pku.edu.cn † Electronic address: zhan-wei.liu@adelaide.edu.au ‡ Electronic address: zhusl@pku.edu.cn

Analytical coalescence formula for particle production in relativistic heavy-ion collisions

“…With w = 0.184 GeV, w s = 0.078 GeV and w c = 0.087 GeV, we obtain reasonable RMS radius values for various hadrons, namely, 0.84 fm for protons (p), 0.87 fm for φ mesons, 1.1 fm for Ξ − , 1.0 fm for Ω − , 1.2 fm for Λ, and 0.98 fm for D 0 . Finally, the parameters N u(d) , N s and N c can be obtained from fitting the measured yields (dN/dy at midrapidity) of p [49], Λ [50], φ [51], Ξ − [52], Ω − [52], and D 0 [53]. For the yields of p, Λ, φ, Ξ − , Ω − and D 0 in central Pb+Pb collisions at √ s N N = 2.76 TeV, it should be noted that the weak decays have already been corrected in the experimental data, but not for the strong decays and electromagnetic decays.…”

Hidden-charm pentaquarks and their hidden-bottom and Bc -like partner states

“…Their decay and production properties were studied in Refs. [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66].…”

Experimental Results on Chiral Magnetic and Vortical Effects

“…A similar asymmetry in photon polarization can also result from the initial global quark polarization [40], which could effectively lead to a polarization of photons [38]. This local imbalance of photon circular polarization could be observed in experiments, e.g., by studying the polarization preference with respect to the RP for photons that convert into e + e − pairs [36]. Similarly, vector mesons that decay into two daughters can also have their polarization preferences measured with the scheme outlined in Ref.…”

“…The average polarization over Λ andΛ evidences the plasma vorticity, while the splitting observation requires much higher statistics to be delivered in the second beam energy scan (BES-II) program at RHIC [35] to signify the magnetic field. The future search for evidence for the initial magnetic field (vorticity) is proposed via photon (vector meson) polarization measurements [36]. The initial magnetic helicity ( − → E · − → B ) of the collision system can be quite large and bears opposite signs in the upper and lower hemispheres.…”

“…Similarly, vector mesons that decay into two daughters can also have their polarization preferences measured with the scheme outlined in Ref. [36], and the helicity separation in this case originates from vorticity [40][41][42].…”