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Nuclear Theory·nucl-th

Tuesday·October 13, 2020

15 papers—9 primary·6 cross-listed

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  1. 10

    Weak asymptotics of wave function for N-particle system and asymptotic filtering

    S.L. Yakovlev

    Asymptotic representations for large values of the hyperradius are constructed for the scattering wave function of a system of particles considered as a generalized function of angular variable coordinates. The coefficients of the asymptotic representations are expressed in terms of the -particle scattering matrix. The phenomenon of asymptotic filtration is discovered, which consists in the fact that only scattering processes contribute to the leading terms of such an asymptotic representation, in which all particles are free both before and after interaction. The obtained representations are used to construct the correct asymptotics of the partial components of the wave function of particles in the hyperspherical representation.

    ↳ math-phmath.MPnucl-thquant-phTeor.Mat.Fiz.(2021)·0 citations
  2. 11

    Bottomonium suppression and elliptic flow using Heavy Quarkonium Quantum Dynamics

    Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸

    We introduce a framework called Heavy Quarkonium Quantum Dynamics (HQQD) which can be used to compute the dynamical suppression of heavy quarkonia propagating in the quark-gluon plasma using real-time in-medium quantum evolution. Using HQQD we compute large sets of real-time solutions to the Schrödinger equation using a realistic in-medium complex-valued potential. We sample 2 million quarkonia wave packet trajectories and evolve them through the QGP using HQQD to obtain their survival probabilities. The computation is performed using three different HQQD model parameter sets in order to estimate our systematic uncertainty. After taking into account final state feed down we compare our results to existing experimental data for the suppression and elliptic flow of bottomonium states and find that HQQD predictions are good agreement with available data for as a function of and collected at 5.02 TeV. In the case of for the various states, we find that the path-length dependence of suppression results in quite small for . Our prediction for the integrated elliptic flow for in the \% centrality class, which now includes an estimate of the systematic error, is = 0.003 0.0007 . We also find that, due to their increased suppression, excited bottomonium states have a larger elliptic flow. Based on this observation we make predictions for and as a function of centrality and transverse momentum.

    ↳ hep-phnucl-thJHEP(2021)·45 citations
  3. 12

    The pole and screening masses of neutral pion in hot and magnetized medium: a comprehensive study in the Nambu--Jona-Lasinio model

    Bingkai Sheng🇨🇳 · Yuanyuan Wang🇨🇳 · Xinyang Wang🇨🇳 · Lang Yu🇨🇳

    In this work, we investigate not only the pole masses but also the screening masses of neutral pions at finite temperature and magnetic field by utilizing the random phase approximation (RPA) approach in the framework of the two-flavor Nambu--Jona-Lasinio (NJL) model. And two equivalent formalisms in the presence of a magnetic field, i.e. the Landau level representation (LLR) and the proper-time representation (PTR), are applied to obtain the corresponding analytical expressions of the polarization functions (except the expressions for the pole masses in the PTR). In order to evaluate the applicable region of the low-momentum expansion (LME), we compare the numerical results within the full RPA (FRPA) with those within the reduced RPA (RRPA), i.e. the RPA in the LME. It is confirmed that the pole masses of {\pi}0in the FRPA suffer a sudden mass jump at the Mott transition temperature when in the presence of external magnetic field, and the Mott transition temperature is catalyzed by the magnetic field. And by analyzing the behaviors of the directional sound velocities of {\pi}0, which are associated with the breaking of the Lorentz invariance by the heat bath and the magnetic field, we clarify the two problems existing in previous literatures: one is that the transverse sound velocities in the medium are always larger than unity and thus violate the law of causality on account of the non-covariant regularization scheme, the other is that the longitudinal sound velocities are identically equal unity at finite temperature on account of the limitation of the derivative expansion method used.

    ↳ hep-phhep-latnucl-thPRD(2021)·42 citations
  4. 13

    Assessing the impact of valence sd neutrons and protons on fusion

    Varinderjit Singh · J. Vadas · T.K. Steinbach · B.B. Wiggins · S. Hudan · R.T. deSouza

    Experimental above-barrier fusion cross-sections for F + C are compared to the fusion excitation functions for O, F, and Ne ions on a carbon target. In comparing the different systems both the differing static size of the incident ions and changes in fusion barrier are accounted for by examining the reduced fusion cross-section. Remaining trends of the fusion cross-section above the barrier which reflect the sensitive interplay of the sd protons and neutrons are observed. The experimental data are also compared to both a widely-used analytical model of near-barrier fusion, as well as a time-dependent Hartree-Fock model. Both models fail to describe the trends observed.

    ↳ nucl-exastro-ph.SRnucl-thPRC(2021)·4 citations
  5. 14

    Hyperon--anti-hyperon polarization asymmetry in relativistic heavy-ion collisions as an interplay between chiral and helical vortical effects

    Victor E. Ambrus🇷🇴 · M. N. Chernodub🇫🇷

    We argue that the enhancement in the spin polarization of anti-hyperons compared to the polarization of the hyperons in noncentral relativistic heavy-ion collisions arises as a result of an interplay between the chiral and helical vortical effects. The chiral vortical effect generates the axial current of quarks along the vorticity axis while the recently found helical vortical effect generates the helicity flow -- the projection of the quark's polarization vector onto its momentum -- along the same axis. For massless fermions, the helical charge corresponds to a difference in the contributions of particles and anti-particles to the axial charge. Assuming that the spin of light quarks transfers to the strange quarks via the vector kaon states ("the spin-vector dominance"), we are able to describe the ratio of the (anti)hyperon spin polarizations, obtained by the STAR group, without fitting parameters. We also argue that the helical vortical effect dominates over the chiral vortical effect and the chiral magnetic effect in the generation of the electric current.

    ↳ hep-phhep-thnucl-thEPJC(2022)·26 citations
  6. 15

    Bottomonium spectroscopy in the quark-gluon plasma

    Georg Wolschin🇩🇪

    The spectroscopic properties of heavy quarkonia are substantially different in the quark-gluon plasma (QGP) that is created in relativistic heavy-ion collisions as compared to the vacuum situation that can be tested in pp collisions at the same center-of-mass energy. In this article, a series of recent works about the dissociation of the Y(nS) and chi_b(nP) states in the hot QGP is summarized. Quarkonia dissociation occurs due to (1) screening of the real quark-antiquark potential, (2) collisional damping through the imaginary part of the potential, and (3) gluon-induced dissociation. In addition, reduced feed-down plays a decisive role for the spin-triplet ground state. Transverse-momentum and centrality-dependent data are well reproduced in Pb-Pb collisions at LHC energies. In the asymmetric p-Pb system, alterations of the parton density functions in the lead nucleus account for the leading fraction of the modifications in cold nuclear matter (CNM), but the hot-medium effects turn out to be relevant in spite of the small initial spatial extent of the fireball, providing additional evidence for the generation of a quark-gluon droplet.

    ↳ hep-phnucl-thInt.J.Mod.Phys.A(2020)·8 citations

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first authorsco-authorsvia INSPIRE