Nuclear Theory·nucl-th

Friday·February 2, 2018

10 papers—4 primary·6 cross-listed

01
Superfluidity in nuclear systems and neutron stars
Armen Sedrakian🇩🇪 · John W. Clark🇺🇸
Nuclear matter and finite nuclei exhibit the property of superfluidity by forming Cooper pairs. We review the microscopic theories and methods that are being employed to understand the basic properties of superfluid nuclear systems, with emphasis on the spatially extended matter encountered in neutron stars, supernova envelopes, and nuclear collisions. Our survey of quantum many-body methods includes techniques that employ Green functions, correlated basis functions, and Monte Carlo sampling of quantum states. With respect to empirical realizations of nucleonic and hadronic superfluids, this review is focused on progress that has been made toward quantitative understanding of their properties at the level of microscopic theories of pairing, with emphasis on the condensates that exist under conditions prevailing in neutron-star interiors. These include singlet $S$ -wave pairing of neutrons in the inner crust, and, in the quantum fluid interior, singlet- $S$ proton pairing and triplet coupled $P$ - $F$ -wave neutron pairing. Additionally, calculations of weak-interaction rates in neutron-star superfluids within the Green function formalism are examined in detail. We close with a discussion of quantum vortex states in nuclear systems and their dynamics in neutron-star superfluid interiors.
nucl-thastro-ph.HEcond-mat.quant-gasEPJA(2019)·201 citations
02
Structure of the orbital excited $N^{*}$ from the Schwinger-Dyson equations
K. Raya🇲🇽 · L.X. Gutiérrez🇲🇽 · A. Bashir🇲🇽
We present progress in the evaluation of $γ^{*} N \to N^{*} (1535)$ transition form factors in a quark-diquark picture of these baryons. Our analysis is based upon the fully-consistent treatment of a vector $\times$ vector contact interaction, embedded in the interlaced formalism of Schwinger-Dyson and Bethe-Salpeter equations.
nucl-thhep-phFew Body Syst.(2018)·6 citations
03
Combination of complex momentum representation and Green's function methods in relativistic mean-field theory
Min Shi · Zhong-Ming Niu · Haozhao Liang
We have combined the complex momentum representation method with the Green's function method in the relativistic mean-field framework to establish the RMF-CMR-GF approach. This new approach is applied to study the halo structure of $^{74}$ Ca. All the continuum level density of concerned resonant states are calculated accurately without introducing any unphysical parameters, and they are independent of the choice of integral contour. The important single-particle wave functions and densities for the halo phenomenon in $^{74}$ Ca are discussed in detail.
nucl-thnucl-exPRC(2018)·16 citations
04
Phenomenology of anomalous chiral transports in heavy-ion collisions
Xu-Guang Huang🇨🇳
High-energy Heavy-ion collisions can generate extremely hot quark-gluon matter and also extremely strong magnetic fields and fluid vorticity. Once coupled to chiral anomaly, the magnetic fields and fluid vorticity can induce a variety of novel transport phenomena, including the chiral magnetic effect, chiral vortical effect, etc. Some of them require the environmental violation of parity and thus provide a means to test the possible parity violation in hot strongly interacting matter. We will discuss the underlying mechanism and implications of these anomalous chiral transports in heavy-ion collisions.
nucl-thhep-phnucl-exEPJ Web Conf.(2018)·1 citation
05
A long-lived remnant neutron star after GW170817 inferred from its associated kilonova
Yun-Wei Yu🇨🇳 · Liang-Duan Liu🇨🇳 · Zi-Gao Dai🇨🇳
The successful joint observation of the gravitational wave event GW170817 and its multi-wavelength electromagnetic counterparts first enables human to witness a definite merger event of two neutron stars (NSs). This historical event confirms the origin of short-duration gamma-ray bursts (GRBs), and in particular, identifies the theoretically-predicted kilonova phenomenon that is powered by radioactive decays of $r$ -process heavy elements. However, whether a long-lived remnant NS could be formed during this merger event remains unknown, although such a central engine has been suggested by afterglow observations of some short-duration GRBs. By invoking this long-lived remnant NS, we here propose a model of hybrid energy sources for the kilonova AT2017gfo associated with GW 170817. While the early emission of AT2017gfo is still powered radioactively as usually suggested, its late emission is primarily caused by delayed energy injection from the remnant NS. In our model, only one single opacity is required and an intermediate value of $κ ≃ 0.97 c m^{2} g^{- 1}$ is revealed, which could be naturally provided by lanthanide-rich ejecta that is deeply ionized by the emission from a wind of the NS. These self-consistent results indicate that a long-lived remnant NS, which must own a very stiff equation of state, had been formed during the merger event of GW170817. This provides a very stringent constraint on the strong interaction in nuclear-quark matter. It is further implied that such GW events could provide a probe of the early spin and magnetic evolutions of NSs, e.g., the burying of surface magnetic fields.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thApJ(2018)·147 citations
06
Polarization and dilepton angular distribution in pion-nucleon collisions
Miklós Zétényi🇭🇺 · Enrico Speranza🇩🇪 · Bengt Friman🇩🇪
We study hadronic polarization and the related anisotropy of the dilepton angular distribution for the reaction $π N \to N e^{+} e^{-}$ . We employ consistent effective interactions for baryon resonances up to spin-5/2 to compute their contribution to the anisotropy coefficient. We show that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We present results for the anisotropy coefficient including the $N (1520)$ and $N (1440)$ resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unraveling the resonance contributions to this process.
↳ hep-phnucl-thFew Body Syst.(2018)·0 citations
07
Direct photon production in relativistic heavy-ion collisions -- a theory update
Charles Gale🇨🇦
For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the "photon flow puzzle", and then focus on a recent development in the theory of photon emission from a non-equilibrium, strongly interacting medium.
↳ hep-phnucl-exnucl-thPoS(2019)·10 citations
08
Quark mass functions and pion structure in the Covariant Spectator Theory
E. P. Biernat🇵🇹 · F. Gross🇺🇸 · M. T. Peña🇵🇹 · A. Stadler🇵🇹 · S. Leitão🇵🇹
The Covariant Spectator Theory is applied to the description of quarks and the pion. The dressed quark mass function is calculated dynamically in Minkowski space and used in the calculation of the pion electromagnetic form factor. The effects of the mass function on the pion form factor and the different quark-pole contributions to the triangle diagram are analyzed.
↳ hep-phnucl-thFew Body Syst.(2018)·2 citations
09
Multiparticle azimuthal cumulants in p+Pb collisions from a multiphase transport model
Mao-Wu Nie🇨🇳 · Peng Huo🇺🇸 · Jiangyong Jia🇺🇸 · Guo-Liang Ma🇨🇳
A new subevent cumulant method was recently developed, which can significantly reduce the non-flow contributions in long-range correlations for small systems compared to the standard cumulant method. In this work, we study multi-particle cumulants in $p$ +Pb collisions at $s_{NN} = 5.02$ TeV with a multiphase transport model (AMPT), including two- and four-particle cumulants ( $c_{2} {2}$ and $c_{2} {4}$ ) and symmetric cumulants [SC(2, 3) and SC(2, 4)]. Our numerical results show that $v_{2} {2}$ is consistent with the experimental data, while the magnitude of $c_{2} {4}$ is smaller than the experimental data, which may indicate either the collectivity is underestimated or some dynamical fluctuations are absent in the AMPT model. For the symmetric cumulants, we find that the results from the standard cumulant method are consistent with the experimental data, but those from the subevent cumulant method show different behaviors. The results indicate that the measurements from the standard cumulant method are contaminated by non-flow effects, especially when the number of produced particles is small. The subevent cumulant method is a better tool to explore the $r e a l$ collectivity in small systems.
↳ hep-phnucl-exnucl-thPRC(2018)·30 citations
10
Anisotropic flow: A case for Bottomonia
Debasish Das (1) · Nirupam Dutta (2) ((1) SINP · (2) NISER)
Studies of $J /$ $ψ$ $v_{2}$ at RHIC and LHC energies have provided important elements towards the understanding on the production mechanisms and on the thermalization of charm quarks. Bottomonia has an advantage since it is a cleaner probe. A brief discussion has been provided for $Υ (1 S)$ $v_{2}$ , which can become the new probe for QGP, including the necessity of studies for small systems.
↳ nucl-exhep-exhep-phnucl-thInt.J.Mod.Phys.A(2018)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE