Nuclear Theory·nucl-th

Tuesday·February 11, 2020

11 papers—3 primary·8 cross-listed

01
The Quenched $g_{A}$ in Nuclei and Emergent Scale Symmetry in Baryonic Matter
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
A recent RIKEN experiment on the quenched $g_{A}$ in the superallowed Gamow-Telller transition from $^{100}$ Sn indicates a role of scale anomaly encoded in the anomalous dimension $β^{'}$ of the gluonic stress tensor $Tr G_{μν}^{2}$ . This observation provides a support to the notion of hidden scale symmetry emerging by strong nuclear correlations with an IR fixed point realized -- in the chiral limit -- in the Nambu-Goldstone mode. We suggest there is an analogy in the way scale symmetry manifests in nuclear medium to the continuity from the unitarity limit at low density (in light nuclei) to the dilaton limit at high density (in compact stars). In between the limits, say, at normal nuclear matter density, the symmetry is not visible, hence hidden.
nucl-thhep-phPRL(2020)·30 citations
02
Impact of longitudinal bulk viscous effects to heavy quark transport in a strongly magnetized hot QCD medium
Manu Kurian🇮🇳 · Vinod Chandra🇮🇳 · Santosh K. Das🇮🇳
The effects of longitudinal bulk viscous pressure on the heavy quark dynamics have been estimated in a strongly magnetized quark-gluon plasma within the Fokker-Planck approach. The bulk viscous modification to the momentum distribution of bulk degrees of freedom has been obtained in the presence of a magnetic field while incorporating the realistic equation of state of the hot magnetized QCD medium. As the magnetic field breaks the isotropy of the medium, the analysis is done along the directions longitudinal and transverse to the field. The longitudinal bulk viscous contribution is seen to have sizable effects in the heavy quark momentum diffusion in the magnetized medium. The dependence of higher Landau levels and the equation of state on the viscous correction to the heavy quark transport has been explored in the analysis.
nucl-thhep-phPRD(2020)·25 citations
03
Local Spin Polarization in 200 GeV Au+Au and 2.76 TeV Pb+Pb Collisions
Hong-Zhong Wu🇨🇳 · Long-Gang Pang🇨🇳 · Xu-Guang Huang🇨🇳 · Qun Wang🇨🇳
We calculated the azimuthal angle dependence of the local spin polarization of hyperons in 200 GeV Au+Au and 2.76 TeV Pb+Pb collisions in the framework of the (3+1)D viscous hydrodynamic model CLVisc with AMPT initial conditions encoding initial orbital angular momenta. We find that the azimuthal angle dependence of the hyperon polarization strongly depends on the choice of the spin chemical potential $Ω_{μν}$ . With $Ω_{μν}$ chosen to be proportional to the temperature vorticity, our simulation shows coincidental results with the recent measurements at RHIC.
nucl-thhep-phNPA(2021)·19 citations
04
Far-forward neutrinos at the Large Hadron Collider
Weidong Bai🇺🇸 · Milind Diwan🇺🇸 · Maria Vittoria Garzelli🇮🇹 · Yu Seon Jeong🇨🇭 · Mary Hall Reno🇺🇸
We present a new calculation of the energy distribution of high-energy neutrinos from the decay of charm and bottom hadrons produced at the Large Hadron Collider (LHC). In the kinematical region of very forward rapidities, heavy-flavor production and decay is a source of tau neutrinos that leads to thousands of { charged-current} tau neutrino events in a 1 m long, 1 m radius lead neutrino detector at a distance of 480 m from the interaction region. In our computation, next-to-leading order QCD radiative corrections are accounted for in the production cross-sections. Non-perturbative intrinsic- $k_{T}$ effects are approximated by a simple phenomenological model introducing a Gaussian $k_{T}$ -smearing of the parton distribution functions, which might also mimic perturbative effects due to multiple initial-state soft-gluon emissions. The transition from partonic to hadronic states is described by phenomenological fragmentation functions. To study the effect of various input parameters, theoretical predictions for $D_{s}^{\pm}$ production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertainties related to the choice of the input parameter values, ultimately affecting the predictions of the tau neutrino event distributions, are discussed. We consider a 3+1 neutrino mixing scenario to illustrate the potential for a neutrino experiment to constrain the 3+1 parameter space using tau neutrinos and antineutrinos. We find large theoretical uncertainties in the predictions of the neutrino fluxes in the far-forward region. Untangling the effects of tau neutrino oscillations into sterile neutrinos and distinguishing a 3+1 scenario from the standard scenario with three active neutrino flavours, will be challenging due to the large theoretical uncertainties from QCD.
↳ hep-phhep-exnucl-exnucl-thJHEP(2020)·66 citations
05
Measuring Nuclear Matter Parameters with NICER and LIGO/Virgo
Josef Zimmerman (1) · Zack Carson (1) · Kristen Schumacher (2) · Andrew W. Steiner (3 and 4) · Kent Yagi (1) ((1) University of Virginia, (2) University of Illinois at Urbana-Champaign, (3) University of Tennessee, (4) Oak Ridge National Laboratory)
The NICER Collaboration recently reported the measurement of the mass and radius of a pulsar PSR J0030+0451. We here use this new measurement to constrain one of the higher-order nuclear matter parameters $K_{sym, 0}$ . We further combine the tidal measurement of the binary neutron star merger GW170817 by LIGO/Virgo to derive a joint 1- $σ$ constraint as $K_{sym, 0} = - 10 2_{- 72}^{+ 71}$ MeV. We believe this is the most reliable bound on the parameter to date under the assumption that there is no new physics above the saturation density which impacts neutron star observations.
↳ astro-ph.HEgr-qcnucl-th63 citations
06
A New Approach to Mass and Radius of Neutron Stars with Supernova Neutrinos
Ken'ichiro Nakazato🇯🇵 · Hideyuki Suzuki🇯🇵
Neutron stars are formed in core-collapse supernova explosions, where a large number of neutrinos are emitted. In this paper, supernova neutrino light curves are computed for the cooling phase of protoneutron stars, which lasts a few minutes. In the numerical simulations, 90 models of the phenomenological equation of state with different incompressibilities, symmetry energies, and nucleon effective masses are employed for a comprehensive study. It is found that the cooling timescale is longer for a model with a larger neutron star mass and a smaller neutron star radius. Furthermore, a theoretical expression of the cooling timescale is presented as a function of the mass and radius and it is found to describe the numerical results faithfully. These findings suggest that diagnosing the mass and radius of a newly formed neutron star using its neutrino signal is possible.
↳ astro-ph.HEhep-phnucl-thApJ(2020)·32 citations
07
Non-perturbative renormalization of the average color charge and multi-point correlators of color charge from a non-Gaussian small- $x$ action
Andre V. Giannini🇯🇵 · Yasushi Nara🇯🇵
The McLerran-Venugopalan (MV) model is a Gaussian effective theory of color charge fluctuations at small- $x$ in the limit of large valence charge density, {\it i}.{\it e}., a large nucleus made of uncorrelated color charges. In this work, we explore the effects of the first non-trivial (even C-parity) non-Gaussian correction on the color charge density to the MV model ("quartic" term) in SU(2) and SU(3) color group in the non-perturbative regime. We compare our (numerical) non-perturbative results to (analytical) perturbative ones in the limit of small or large non-Gaussian fluctuations. The couplings in the non-Gaussian action, $μ ˉ$ for the quadratic and $κ_{4}$ for the quartic term, need to be renormalized in order to match the two-point function in the Gaussian theory. We investigate three different choices for the renormalization of these couplings: i) $κ_{4}$ is proportional to a power of $μ ˉ$ ; ii) $κ_{4}$ is kept constant and iii) $μ ˉ$ is kept constant. We find that the first two choices lead to a scenario where the small- $x$ action evolves towards a theory dominated by large non-Gaussian fluctuations, regardless of the system size, while the last one allows for controlling the deviations from the MV model.
↳ hep-phnucl-thNPA(2021)·5 citations
08
Covariant Spin Kinetic Theory I: Collisionless Limit
Yu-Chen Liu🇨🇳 · Kazuya Mameda🇨🇳 · Xu-Guang Huang🇨🇳
We develop a covariant kinetic theory for massive fermions in curved spacetime and external electromagnetic field based on quantum field theory. We derive four coupled semi-classical kinetic equations accurate at $O (ℏ)$ , which describe the transports of particle number and spin degrees of freedom. The relation with the chiral kinetic theory is discussed. As an application, we study the spin polarization in the presence of finite Riemann curvature and electromagnetic field in both local and global equilibrium states.
↳ hep-phcond-mat.mes-hallhep-thnucl-thCPC(2020)·116 citations
09
Study of the $^{25}$ Mg(d,p) $^{26}$ Mg reaction to constrain the $^{25}$ Al(p, $γ$ ) $^{26}$ Si resonant reaction rates in nova burning conditions
C. B. Hamill · P. J. Woods · D. Kahl · R. Longland · J. P. Greene · C. Marshall · F. Portillo · K. Setoodehnia
The rate of the $^{25}$ Al( $p$ , $γ$ ) $^{26}$ Si reaction is one of the few key remaining nuclear uncertainties required for predicting the production of the cosmic $γ$ -ray emitter $^{26}$ Al in explosive burning in novae. This reaction rate is dominated by three key resonances ( $J^{π} = 0^{+}$ , $1^{+}$ and $3^{+}$ ) in $^{26}$ Si. Only the $3^{+}$ resonance strength has been directly constrained by experiment. A high resolution measurement of the $^{25}$ Mg( $d$ , $p$ ) reaction was used to determine spectroscopic factors for analog states in the mirror nucleus, $^{26}$ Mg. A first spectroscopic factor value is reported for the $0^{+}$ state at 6.256 MeV, and a strict upper limit is set on the value for the $1^{+}$ state at 5.691 MeV, that is incompatible with an earlier ( $^{4}$ He, $^{3}$ He) study. These results are used to estimate proton partial widths, and resonance strengths of analog states in $^{26}$ Si contributing to the $^{25}$ Al( $p$ , $γ$ ) $^{26}$ Si reaction rate in nova burning conditions.
↳ nucl-exastro-ph.SRnucl-thEPJA(2020)·9 citations
10
Relativistic dissipative spin dynamics in the relaxation time approximation
Samapan Bhadury🇮🇳 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Avdhesh Kumar🇵🇱 · Radoslaw Ryblewski🇵🇱
The concept of the Wigner function is used to construct a semi-classical kinetic theory describing the evolution of the axial-current phase-space density of spin-1/2 particles in the relaxation time approximation. The resulting approach can be used to study spin-polarization effects in relativistic matter, in particular, in heavy-ion collisions. An expression for the axial current based on the classical treatment of spin is also introduced and we show that it is consistent with earlier calculations using Wigner functions. Finally, we derive non-equilibrium corrections to the spin tensor, which are used to define, for the first time, the structure of spin transport coefficients in relativistic matter.
↳ hep-phnucl-thPLB(2021)·178 citations
11
Jet quenching and medium response in high-energy heavy-ion collisions: a review
Shanshan Cao🇺🇸 · Xin-Nian Wang🇨🇳
Jet quenching has been used successfully as a hard probe to study properties of the quark-gluon plasma (QGP) in high-energy heavy-collisions at both the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC). We will review recent progresses in theoretical and phenomenological studies of jet quenching with jet transport models. Special emphasis is given to effects of jet-induced medium response on a wide variety of experimental measurements and their implication on extracting transport properties of the QGP in heavy-ion collisions.
↳ hep-phnucl-thRept.Prog.Phys.(2021)·250 citations

Affiliations

first authorsco-authorsvia INSPIRE