Nuclear Theory·nucl-th

Tuesday·August 4, 2020

17 papers—8 primary·9 cross-listed

09
Bethe-Salpeter amplitudes of Upsilons
Rasmus Larsen🇺🇸 · Stefan Meinel🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸
Based on lattice non-relativistic QCD (NRQCD) studies we present results for Bethe-Salpeter amplitudes for $Υ (1 S)$ , $Υ (2 S)$ and $Υ (3 S)$ in vacuum as well as in quark-gluon plasma. Our study is based on 2+1 flavor $4 8^{3} \times 12$ lattices generated using the Highly Improved Staggered Quark (HISQ) action and with a pion mass of $161$ MeV. At zero temperature the Bethe-Salpeter amplitudes follow the expectations based on non-relativistic potential models. At non-zero temperatures, the interpretation of Bethe-Salpeter amplitudes turns out to be more nuanced, but consistent with our previous lattice QCD study of excited Upsilons in quark-gluon plasma.
↳ hep-lathep-phnucl-thPRD(2020)·23 citations
10
Selected Science Opportunities for the EicC
Xurong Chen🇨🇳 · Feng-Kun Guo🇨🇳 · Craig D. Roberts🇨🇳 · Rong Wang🇨🇳
An electron ion collider has been proposed in China (EicC). It is anticipated that the facility would provide polarised electrons, protons and ion beams, in collisions with large centre-of-mass energy. This discussion highlights its potential to address issues that are central to understanding the emergence of mass within the Standard Model, using examples that range from the exploration of light-meson structure, through measurements of near-threshold heavy-quarkonia production, and on to studies of the spectrum of exotic hadrons.
↳ hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2020)·89 citations
11
Baryonic Sources of Thermal Photons
Nathan P. M. Holt🇺🇸 · Ralf Rapp🇺🇸
Thermal radiation of photons and dileptons from hadronic matter plays an essential role in understanding electromagnetic emission spectra in high-energy heavy-ion collisions. In particular, baryons and anti-baryons have been found to be strong catalysts for electromagnetic radiation, even at collider energies where the baryon chemical potential is small. Here, we conduct a systematic analysis of $π$ - and $ω$ -meson-induced reactions off a large set of baryon states. The interactions are based on effective hadronic Lagrangians where the parameters are quantitatively constrained by empirical information from vacuum decay branchings and scattering data, and gauge invariance is maintained by suitable regularization procedures. The thermal emission rates are computed using kinetic theory but can be directly compared to previous calculations using hadronic many-body theory. The comparison to existing calculations in the literature reveals our newly identified contributions to be rather significant.
↳ hep-phnucl-thEPJA(2020)·7 citations
12
Flavor-dependent U(3) Nambu Jona Lasinio coupling constant
Fabio L. Braghin🇧🇷
A non-perturbative one gluon exchange quark-antiquark interaction is considered to compute flavor dependent U(3) Nambu-Jona-Lasinio (NJL)-type interaction of the form $G_{ij, Γ} (ψ ˉ λ_{i} Γ ψ) (ψ ˉ λ_{j} Γ ψ)$ for $i, j = 0...8$ and $Γ = I, i γ_{5}$ from one loop polarization process with non degenerate u-d-s quark effective masses. The resulting NJL-type coupling constants in all channels are resolved in the long-wavelength limit and numerical results are presented for different choices of an effective gluon propagator. Leading deviations with respect to a flavor symmetric coupling constant are found to be of the order of $(M_{f_{2}}^{*} - M_{f_{1}}^{*})^{n} / (M_{f_{2}}^{*} + M_{f_{1}}^{*})^{n}$ , for $n = 1, 2$ , where $M_{f_{i}}^{*}$ are the effective masses of quarks $f_{1}, f_{2} = u, d$ and $s$ . The scalar channel coupling constants $G_{ij, s}$ can be considerably smaller than pseudoscalar ones. The effect of the flavor-dependence of coupling constants for the masses of pions and kaons may be nearly of the same order of magnitude as the effect of the u,d and s quark mass non-degeneracy. The effect of these coupling constants is also verified for some of the light scalar mesons masses, usually described by quark-antiquark states, and for some observables of the pseudoscalar mesons.
↳ hep-phnucl-thPRD(2021)·15 citations
13
Chiral properties of (2+1)-flavor QCD in strong magnetic fields at zero temperature
H.-T. Ding🇨🇳 · S.-T. Li🇨🇳 · A. Tomiya🇺🇸 · X.-D. Wang🇨🇳 · Y. Zhang🇨🇳
We present lattice QCD results for masses and magnetic polarizabilities of light and strange pseudoscalar mesons, chiral condensates, decay constants of neutral pion, and neutral kaon in the presence of background magnetic fields with $e B$ ranging up to around 3.35 GeV $^{2}$ ( $\sim 70 M_{π}^{2}$ ) in the vacuum. The computations were carried out in (2+1)-flavor QCD mostly on $3 2^{3} \times 96$ lattices using the highly improved staggered quark action with $M_{π} \approx$ 220 MeV at zero temperature. We find that the masses of neutral pseudoscalar mesons monotonously decrease as the magnetic field strength grows and then saturate at a nonzero value, while there exists a nonmonotonous behavior of charged pion and kaon masses in the magnetic field. We observe a $q B$ scaling of the up and down quark flavor components of neutral pion mass, neutral pion decay constant as well as the quark chiral condensates at 0.05 $≲ e B ≲$ 3.35 GeV $^{2}$ . We show that the correction to the Gell-Mann-Oakes-Renner relation involving the neutral pion is less than 6% and the correction for the relation involving neutral kaon is less than 30% at $e B ≲$ 3.35 GeV $^{2}$ . We also derive the Ward-Takahashi identities for QCD in the magnetic field in the continuum formulation including the relation between integrated neutral pseudoscalar meson correlators and chiral condensates.
↳ hep-lathep-phhep-thnucl-thPRD(2021)·110 citations
14
Jet Charge: A Flavor Prism for Spin Asymmetries at the EIC
Zhong-Bo Kang🇺🇸 · Xiaohui Liu🇨🇳 · Sonny Mantry🇺🇸 · Ding Yu Shao🇺🇸
We propose the jet charge observable as a novel probe of flavor structure in the nucleon spin program at the Electron Ion Collider (EIC). We show that jet charge measurements can substantially enhance the sensitivity of spin asymmetries to different partonic flavors in the nucleon. This sensitivity can be further improved by constructing the jet charge using only a subset of hadron species (pions or kaons) in the jet. As an example, we use the Sivers asymmetry in back-to-back electron-jet production at the EIC to show that the jet charge can be a unique tool in constraining the Sivers function for different partonic flavors.
↳ hep-phhep-exnucl-exnucl-thPRL(2020)·66 citations
15
Doubly charmed multibaryon systems
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
We study two- and three-baryon systems with two units of charm looking for possible bound states or resonances. All two-baryon interactions are consistently derived from a constituent quark model tuned in the light-flavor hadron phenomenology: spectra and interactions. The presence of the heavy quarks makes the two-body interactions simpler than in the light-flavor sector. Our results show a narrow two-body resonance with quantum numbers $(I, J^{P}) = (0, 0^{+})$ . It is located 6.2 MeV below the $Σ_{c} Σ_{c}$ threshold and has a width of 4.7 MeV. The foregoing two-body state contributes to generate a $N Σ_{c} Σ_{c}$ resonance with quantum numbers $(I, J^{P}) = (1/2, 1/ 2^{+})$ and a separation energy of 0.2 MeV.
↳ hep-phnucl-thEPJC(2020)·22 citations
16
Double-heavy tetraquark states with heavy diquark-antiquark symmetry
Jian-Bo Cheng🇨🇳 · Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Zong-Guo Si🇨🇳 · Tao Yao🇨🇳
We calculate the masses of the $QQ q ˉ q ˉ$ ( $Q = c, b$ ; $q = u, d, s$ ) tetraquark states with the aid of heavy diquark-antiquark symmetry (HDAS) and the chromomagnetic interaction (CMI) model. The masses of the highest-spin ( $J = 2$ ) tetraquarks that have only the $(QQ)_{3 ˉ_{c}} (q ˉ q ˉ)_{3_{c}}$ color structure are related with those of conventional hadrons using HDAS. Thereafter, the masses of their partner states are determined with the mass splittings in the CMI model. Our numerical results reveal that: (i) the lightest $cc n ˉ n ˉ$ ( $n = u, d$ ) is an $I (J^{P}) = 0 (1^{+})$ state around 3929 MeV (53 MeV above the $D D^{*}$ threshold) and none of the double-charm tetraquarks are stable; (ii) the stable double-bottom tetraquarks are the lowest $0 (1^{+})$ $bb n ˉ n ˉ$ around 10488 MeV ( $\approx 116$ MeV below the $B B^{*}$ threshold) and the lowest $1/2 (1^{+})$ $bb n ˉ s ˉ$ around 10671 MeV ( $\approx 20$ MeV below the $B B_{s}^{*} / B_{s} B^{*}$ threshold); and (iii) the two lowest $b c n ˉ n ˉ$ tetraquarks, namely the lowest $0 (0^{+})$ around 7167 MeV and the lowest $0 (1^{+})$ around 7223 MeV, are near-threshold states. Moreover, we discuss the constraints on the masses of double-heavy hadrons. Specifically, for the lowest nonstrange tetraquarks, we obtain $T_{cc} < 3965$ MeV, $T_{bb} < 10627$ MeV, and $T_{b c} < 7199$ MeV.
↳ hep-phhep-exhep-latnucl-ex+1CPC(2021)·96 citations
17
Bounds on transport from univalence and pole-skipping
Sašo Grozdanov🇺🇸
Bounds on transport represent a way of understanding allowable regimes of quantum and classical dynamics. Numerous such bounds have been proposed, either for classes of theories or (by using general arguments) universally for all theories. Few are exact and inviolable. I present a new set of methods and sufficient conditions for deriving exact, rigorous, and sharp bounds on all coefficients of hydrodynamic dispersion relations, including diffusivity and the speed of sound. These general techniques combine analytic properties of hydrodynamics and the theory of univalent (complex holomorphic and injective) functions. Particular attention is devoted to bounds relating transport to quantum chaos, which can be established through pole-skipping in theories with holographic duals. Examples of such bounds are shown along with holographic theories that can demonstrate the validity of the conditions involved. I also discuss potential applications of univalence methods to bounds without relation to chaos, such as for example the conformal bound on the speed of sound.
↳ hep-thcond-mat.str-elmath-phmath.MP+2PRL(2021)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE