Nuclear Theory·nucl-th

Friday·March 15, 2019

8 papers—4 primary·4 cross-listed

01
All the Fun of the FAIR: Fundamental physics at the Facility for Antiproton and Ion Research
M. Durante🇮🇹 · P. Indelicato🇫🇷 · B. Jonson🇸🇪 · V. Koch🇺🇸 · K. Langanke🇩🇪 · Ulf-G. Meißner🇩🇪 · E. Nappi🇮🇹 · T. Nilsson🇸🇪 · Th. Stöhlker🇩🇪 · E. Widmann🇦🇹 · M. Wiescher🇺🇸
The Facility for Antiproton and Ion Research (FAIR) will be the accelerator-based flagship research facility in many basic sciences and their applications in Europe for the coming decades. FAIR will open up unprecedented research opportunities in hadron and nuclear physics, in atomic physics and nuclear astrophysics as well as in applied sciences like materials research, plasma physics and radiation biophysics with applications towards novel medical treatments and space science. FAIR is currently under construction as an international facility at the campus of the GSI Helmholtzzentrum for Heavy-Ion Research in Darmstadt, Germany. While the full science potential of FAIR can only be harvested once the new suite of accelerators and storage rings is completed and operational, some of the experimental detectors and instrumentation are already available and will be used starting in summer 2018 in a dedicated research program at GSI, exploiting also the significantly upgraded GSI accelerator chain. The current manuscript summarizes how FAIR will advance our knowledge in various research fields ranging from a deeper understanding of the fundamental interactions and symmetries in Nature to a better understanding of the evolution of the Universe and the objects within.
nucl-thhep-exhep-phnucl-ex+1Phys.Scripta(2019)·111 citations
02
Symmetry energy at supra-saturation densities via the Gravitational Waves from GW170817
Hui Tong🇨🇳 · Peng-Wei Zhao🇨🇳 · Jie Meng🇨🇳
Motivated by the historical detection of gravitational waves from GW170817, the neutron star and the neutron drop, i.e., a certain number of neutrons confined in an external field, are systematically investigated by ab initio calculations as well as the nonrelativistic and relativistic state-of-art density functional theories. Strong correlations are found among the neutron star tidal deformability, the neutron star radius, the root-mean-square radii of neutron drops, and the symmetry energies of nuclear matter at supra-saturation densities. From these correlations and the upper limit on the tidal deformability extracted from GW170817, the neutron star radii, the neutron drop radii, and the symmetry energy at twice saturation density are respectively constrained as $R_{1.4 M_{⊙}} ⩽ 12.94$ km, $R_{nd} ⩽ 2.36$ fm, and $E_{sym} (2 ρ_{0}) ⩽ 53.2$ MeV.
nucl-thPRC(2020)·61 citations
03
Universal scaling of conserved charge in the stochastic diffusion dynamics
Shanjin Wu · Huichao Song
In this paper, we explore the Kibble-Zurek scaling of the conserved charge, using the stachastic diffusion dynamics. After determining the characteristic scales $τ_{k z}$ and $l_{k z}$ and properly rescaling the traditional correlation function and cumulant, we construct universal functions for both the two-point correlation function $C (y_{1} - y_{2}; τ)$ and second-order cumulant $K (Δ y, τ)$ of the conserved charge in the critical regime, which are insensitive to the initial temperature and a parameter in the mapping between 3D Ising model and the hot QCD system near the critical point.
nucl-thCPC(2019)·10 citations
04
Hadron transverse momentum distributions of the Tsallis normalized and unnormalized statistics
A.S. Parvan🇷🇺 · T. Bhattacharyya🇷🇺
The exact analytical formulas for the transverse momentum distributions of the Bose-Einstein, Fermi-Dirac and Maxwell-Boltzmann statistics of particles with nonzero mass in the framework of the Tsallis normalized and Tsallis unnormalized (also known as Tsallis-1 and Tsallis-2) statistics have been consistently derived. The final exact results were expressed in terms of the series expansions in the integral representation. The zeroth term approximation to both quantum and classical statistics of particles has been introduced. We have revealed that the phenomenological classical Tsallis distribution (widely used in high energy physics) is equal to the distribution of the Tsallis unnormalized statistics in the zeroth term approximation, but the phenomenological quantum Tsallis distributions (introduced by definition on the basis of the generalized entropy of the ideal gas) do not correspond to the distributions of the Tsallis statistics. We have found that in the ranges of the entropic parameter relevant to the processes of high-energy physics ( $q < 1$ for Tsallis-1 and $q > 1$ for Tsallis-2) the Tsallis statistics is divergent. Therefore, to obtain physical results, we have regularized the Tsallis statistics by introducing an upper cut-off in the series expansion. The exact numerical results for the Bose-Einstein, Fermi-Dirac and Maxwell-Boltzmann statistics of particles in the Tsallis normalized and unnormalized statistics have been obtained. We observed that the exact results of the Tsallis statistics strongly enhanced the production of high- $p_{T}$ hadrons in comparison with the usual phenomenological Tsallis distribution function at the same values of $q$ . The $q$ -duality of the Tsallis normalized and unnormalized statistics for the massive particles was studied.
nucl-thhep-phEPJA(2020)·23 citations
05
The tidal deformability of an anisotropic compact star: Implications of GW170817
Bhaskar Biswas · Sukanta Bose
We use gravitational wave (GW) and electromagnetic (EM) observations of GW170817 to constrain the extent of pressure anisotropy in it. While it is quite likely that the pressure inside a neutron star is mostly isotropic, certain physical processes or characteristics, such as phase transitions in nuclear matter or the presence of strong magnetic fields, can introduce pressure anisotropy. In this work, we show that anisotropic pressure in neutron stars can reduce their tidal deformability substantially. For the anisotropy-pressure model of Bowers and Liang and a couple of relativistic EOSs -- DDH $δ$ and GM1 -- we demonstrate that this reduction in spherical neutron stars with masses in the range of 1 to 2 $M_{⊙}$ can be 23% to 46%. This suggests that certain EOSs that are ruled out by GW170817 observations, under assumptions of pressure isotropy, can become viable if the stars had a significant enough anisotropic pressure component, but do not violate causality. We also show how the inference of the star radius can be used to rule out certain EOSs (such as GM1), even for high anisotropic pressure, because their radii are larger than what the observations find.
↳ gr-qcastro-ph.HEnucl-thPRD(2019)·100 citations
06
Constraining compact star properties with nuclear saturation parameters
Jia Jie Li (ITP, Frankfurt)🇩🇪 · Armen Sedrakian (FIAS)🇩🇪
A set of hadronic equations of state (EoSs) derived from relativistic density functional theory and constrained by terrestrial experiments, astrophysical observations, in particular by the GW170817 event, and chiral effective field theory ( $χ$ EFT) of neutron matter is used to explore the sensitivity of the EoS parameterization on the few nuclear matter characteristics defined at the saturation density. We find that the gross properties of compact stars are most sensitive to the isoscalar skewness coefficient $Q_{sat}$ and the isovector slope coefficient $L_{sym}$ around saturation density, since the higher order coefficients, such as $K_{sym}$ , are fixed by our model. More specifically, (i) among these $Q_{sat}$ is the dominant parameter controlling both the maximum mass and the radii of compact stars while $L_{sym}$ is constrained somewhat by $χ$ EFT of neutron matter; (ii) massive enough ( $M \sim 2.0 M_{⊙})$ compact stars featuring both hyperons and $Δ$ resonances can be obtained if the value of $Q_{sat}$ is large enough; (iii) the emergence of $Δ$ 's reduces the radius of a canonical mass ( $M \sim 1.4 M_{⊙})$ compact star thus easing the tension between the predictions of the relativistic density functionals and the inferences from the X-ray observation of nearby isolated neutron stars.
↳ astro-ph.HEnucl-thPRC(2019)·53 citations
07
Photon induced processes in semi-central nucleus-nucleus collisions
Antoni Szczurek🇵🇱
We calculate total and differential cross sections for $J / ψ$ photoproduction in ultrarelativistic lead-lead collisions at the LHC energy $s_{N N} = 2.76$ TeV. We use a simple model based on vector dominance picture and multiple scattering of the hadronic ( $c c ˉ$ ) state in a cold nucleus. In our analysis we use Glauber formulae for calculating $σ_{t o t, J / ψ P b}$ which is a building block of our model. For semi-central collisions a modification of the photon flux is necessary. We discuss how to effectively correct photon fluxes for geometry effects. We try to estimate the cross sections for different centrality bins and for $J / ψ$ mesons emitted in forward rapidity range ( $2.5 < y < 4$ ) corresponding to the ALICE experimental results. We discuss similar analysis for dilepton production in ultrarelativistic heavy-ion collisions at very low pair transverse momenta, $P_{T} \leq 0.15$ \,GeV. We investigate the interplay of thermal radiation with photon annihilation processes, $γ γ \to l^{+} l^{-}$ , due to the coherent electromagnetic fields of the colliding nuclei. For the thermal radiation, we employ the emission from the QGP and hadronic phases with in-medium vector spectral functions. We first verify that the combination of photon fusion, thermal radiation and final-state hadron decays gives a fair description of the low- $P_{T}$ invariant-mass as well as $P_{T}$ distributions as measured recently by the STAR collaboration in $s_{N N}$ =200\,GeV Au+Au collisions for different centralities. The coherent contribution dominates in peripheral collisions, while thermal radiation shows a significantly stronger increase with centrality. We also provide predictions for the ALICE experiment at the LHC. The resulting excitation function reveals a nontrivial interplay of photoproduction and thermal radiation.
↳ hep-phnucl-thActa Phys.Polon.B(2019)·0 citations
08
Discovery potential of multi-ton xenon detectors in neutrino electromagnetic properties
Chung-Chun Hsieh🇹🇼 · Lakhwinder Singh🇹🇼 · Chih-Pan Wu🇹🇼 · Jiunn-Wei Chen🇹🇼 · Hsin-Chang Chi🇹🇼 · C.-P. Liu🇹🇼 · Mukesh K. Pandey🇹🇼 · Henry T. Wong🇹🇼
Next-generation xenon detectors with multi-ton-year exposure are powerful direct probes of dark matter candidates, in particular the favorite weakly-interacting massive particles. Coupled with the features of low thresholds and backgrounds, they are also excellent telescopes of solar neutrinos. In this paper, we study the discovery potential of ton-scale xenon detectors in electromagnetic moments of solar neutrinos. Relevant neutrino-atom scattering processes are calculated by applying a state-of-the-arts atomic many-body method--relativistic random phase approximation (RRPA). Limits on these moments are derived from existing data and estimated with future experiment specifications. With one ton-year exposure, XENON-1T can improve the effective milli-charge constraint by a factor two. With LZ and DARWIN, the projected improvement on the solar neutrino effective milli-charge(magnetic moment) is around 7(2) times smaller than the current bound. If LZ can keep the same background level and push the electron recoil threshold to 0.5 keV, the projected improvement on milli-charge(magnetic moment) is about 10(3) times smaller than the current bound.
↳ hep-phhep-exnucl-exnucl-thPRD(2019)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE