Nuclear Theory·nucl-th

Monday·August 10, 2020

12 papers—4 primary·8 cross-listed

01
Structure Factors of Neutron Matter at Finite Temperature
Andrei Alexandru🇺🇸 · Paulo Bedaque🇺🇸 · Evan Berkowitz🇺🇸 · Neill C. Warrington🇺🇸
We compute continuum and infinite volume limit extrapolations of the structure factors of neutron matter at finite temperature and density. Using a lattice formulation of leading-order pionless effective field theory, we compute the momentum dependence of the structure factors at finite temperature and at densities beyond the reach of the virial expansion. The Tan contact parameter is computed and the result agrees with the high momentum tail of the vector structure factor. All errors, statistical and systematic, are controlled for. This calculation is a first step towards a model-independent understanding of the linear response of neutron matter at finite temperature, a realm until now little explored.
nucl-thastro-ph.HEcond-mat.quant-gashep-latPRL(2021)·13 citations
02
Constraining the nuclear symmetry energy and properties of neutron star from GW170817 by Bayesian analysis
Yuxi Li · Houyuan Chen · Dehua Wen · Jing Zhang
Based on the distribution of tidal deformabilities and component masses of binary neutron star merger GW170817, the parametric equation of states (EOS) are employed to probe the nuclear symmetry energy and the properties of neutron star. To obtain a proper distribution of the parameters of the EOS that is consistent with the observation, Bayesian analysis is used and the constraints of causality and maximum mass are considered. From this analysis, it is found that the symmetry energy at twice the saturation density of nuclear matter can be constrained within $E_{sy m} (2 ρ_{0})$ = $34. 5_{- 2.3}^{+ 20.5}$ MeV at 90\% credible level. Moreover, the constraints on the radii and dimensionless tidal deformabilities of canonical neutron stars are also demonstrated through this analysis, and the corresponding constraints are 10.80 km $< R_{1.4} <$ 13.20 km and $133 < Λ_{1.4} < 686$ at 90\% credible level, with the most probable value of $R ˉ_{1.4}$ = 12.60 km and $Λ ˉ_{1.4}$ = 500, respectively. With respect to the prior, our result (posterior result) prefers a softer EOS, corresponding to a lower expected value of symmetry energy, a smaller radius and a smaller tidal deformability.
nucl-thastro-ph.HEEPJA(2021)·33 citations
03
Elliptic flow of hadrons in equal-velocity quark combination mechanism in relativistic heavy-ion collisions
Jun Song🇨🇳 · Hai-hong Li🇨🇳 · Feng-lan Shao🇨🇳
We apply a quark combination model with equal-velocity combination (EVC) approximation to study the elliptic flow ( $v_{2}$ ) of hadrons in heavy-ion collisions in a wide collision energy range ( $s_{N N} =$ 27 - 5020 GeV). Utilizing the simple relationship between $v_{2}$ of hadrons and those of quarks under EVC, we find that $v_{2}$ of up/down quarks obtained by experimental data of proton is consistent with that obtained by data of $Λ$ and $Ξ$ . $v_{2}$ of strange quarks obtained by data of $Ω$ is consistent with that obtained by data of $Λ$ and $Ξ$ , and at RHIC energies it is also consistent with that obtained by data of $ϕ$ . This means that $v_{2}$ of these hadrons have a common quark-level source. Using data of $D^{0}$ , we obtain $v_{2}$ of charm quarks with $p_{T} ≲ 6$ GeV/c. We find that under EVC charm quark dominates $v_{2}$ of $D$ mesons at low $p_{T}$ but light-flavor quarks significantly contribute to $v_{2}$ of $D$ mesons in the range $3 ≲ p_{T} ≲ 8$ GeV/c. We predict $v_{2}$ of charmed baryons $Λ_{c}^{+}$ and $Ξ_{c}^{0}$ which show a significant enhancement at intermediate $p_{T}$ due to the double contribution of light-flavor quarks. The properties of the obtained quark $v_{2}$ under EVC are studied and a regularity for $v_{2}$ of quarks as the function of $p_{T} / m$ is found.
nucl-thEPJC(2021)·16 citations
04
Extracting $σ_{π N}$ from pionic atoms
Eliahu Friedman · Avraham Gal
We discuss a recent extraction of the $π N$ $σ$ term $σ_{π N}$ from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, $σ_{π N}^{FG} = 57 \pm 7$ MeV, is directly connected via the Gell-Mann--Oakes--Renner expression to the medium-renormalized $π N$ isovector scattering amplitude near threshold. It compares well with the value derived recently by the Bern-Bonn-Jülich group, $σ_{π N}^{RS} = 58 \pm 5$ MeV, using the Roy-Steiner equations to control the extrapolation of the vanishingly small near threshold $π N$ isoscalar scattering amplitude to zero pion mass.
nucl-thhep-phActa Phys. Pol. B 51 (2020) 45 and AIP Co…
05
Factorized approach to radiative corrections for inelastic lepton-hadron collisions
Tianbo Liu🇺🇸 · W. Melnitchouk🇺🇸 · Jian-Wei Qiu🇺🇸 · N. Sato🇺🇸
We propose a factorized approach to QED radiative corrections for inclusive and semi-inclusive deep-inelastic scattering to systematically account for QED and QCD radiation contributions to both processes on equal footing. This is achieved by utilizing factorization to resum logarithmically enhanced QED radiation into universal lepton distribution and fragmentation (or jet) functions. Numerical simulations suggest that the QED effects induced by the rotational distortion of the hadron transverse momentum, arising from the mismatch between the experimental Breit frame and the true photon-hadron frame, can be as large as 50\% for moderate $Q$ , and become increasingly important for large transverse momenta. Our framework provides a uniform treatment of radiative effects for extracting three-dimensional hadron structure from high-energy lepton-hadron scattering at current and future facilities, such as the Electron-Ion Collider.
↳ hep-phhep-exnucl-exnucl-thPRD(2021)·35 citations
06
The emission of electromagnetic radiation from the early stages of relativistic heavy-ion collisions
Jessica Churchill🇨🇦 · Li Yan🇨🇳 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We estimate the production of electromagnetic radiation (real and virtual photons) from the early, pre-equilibrium, stage of relativistic heavy-ion collisions. The parton dynamics are obtained as a solution of the Boltzmann equation in the Fokker-Planck diffusion limit. The photon and dilepton rates are integrated and the obtained yields are compared with those from standard sources and with available experimental data. Non-equilibrium photon spectra are predicted for Pb+Pb at $s_{NN} = 5.02$ TeV.
↳ hep-phnucl-exnucl-thPRC(2021)·35 citations
07
Decay Spectroscopy of $^{129}$ Cd
Y. Saito🇨🇦 · I. Dillmann🇨🇦 · R. Krücken🇨🇦 · N. Bernier🇨🇦 · G. C. Ball🇨🇦 · M. Bowry🇨🇦 · C. Andreoiu🇨🇦 · H. Bidaman🇨🇦 · V. Bildstein🇨🇦 · P. Boubel🇨🇦 · C. Burbadge🇨🇦 · R. Caballero-Folch🇨🇦 and 33 other authors
Excited states of $^{129}$ In populated following the $β$ -decay of $^{129}$ Cd were experimentally studied with the GRIFFIN spectrometer at the ISAC facility of TRIUMF, Canada. A 480-MeV proton beam was impinged on a uranium carbide target and $^{129}$ Cd was extracted using the Ion Guide Laser Ion Source (IG-LIS). $β$ - and $γ$ -rays following the decay of $^{129}$ Cd were detected with the GRIFFIN spectrometer comprising the plastic scintillator SCEPTAR and 16 high-purity germanium (HPGe) clover-type detectors. %, along with the $β$ -particles were detected with SCEPTAR. From the $β$ - $γ$ - $γ$ coincidence analysis, 32 new transitions and 7 new excited states were established, expanding the previously known level scheme of $^{129}$ In. The $lo g f t$ values deduced from the $β$ -feeding intensities suggest that some of the high-lying states were populated by the $ν 0 g_{7/2} \to π 0 g_{9/2}$ allowed Gamow-Teller (GT) transition, which indicates that the allowed GT transition is more dominant in the $^{129}$ Cd decay than previously reported. Observation of fragmented Gamow-Teller strengths is consistent with theoretical calculations.
↳ nucl-exnucl-thPRC(2020)·3 citations
08
Investigating the pion source function in heavy-ion collisions with the EPOS model
Maria Stefaniak🇵🇱 · Daniel Kincses🇭🇺
By measuring the momentum correlations of pions created in heavy-ion collisions we can gain information about the space-time geometry of the particle emitting source. Recent experimental results from multiple different collaborations demonstrated that to properly describe the shape of the measured correlation functions, one needs to go beyond the Gaussian approximation. Some studies suggest that the Levy distribution could provide a good description of the source. While there are already many experimental results, there is very little input from the phenomenology side in explanation of the observed non-Gaussian source shapes. The EPOS model is a sophisticated hybrid model where the evolution of the newly-created system is governed by Parton-Based Gribov-Regge theory. It has already proved to be successful in describing many different experimental observations for the systems characterized by baryon chemical potential close to zero, but so far the source shape has not been explored in detail. In this paper we discuss studies of the pion emitting source based on the theoretical approach of the EPOS model.
↳ hep-phnucl-thProc.SPIE Int.Soc.Opt.Eng.(2020)·2 citations
09
Exclusive vector meson production in electron-ion collisions at the EIC, LHeC and FCC- $e h$
Victor P. Goncalves🇧🇷 · Daniel E. Martins🇧🇷 · Celso R. Sena🇧🇷
The exclusive vector meson production in electron-ion collisions for the energies of the future colliders is investigated. We present predictions for the coherent and incoherent $ϕ$ and $J / ψ$ production in $e A u$ collisions considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non-linear corrections to the QCD dynamics. The cross sections and transverse momentum distributions are estimated assuming the energies of the Electron-Ion Collider (EIC), Large Hadron Electron Collider (LHeC) and Future Circular Collider (FCC- $e h$ ). Our results indicate that a future experimental analysis of these processes can shed light on the modeling of the gluon saturation effects and constrain the description of the QCD dynamics at high energies.
↳ hep-phnucl-thNPA(2020)·13 citations
10
Machine learning-based event generator for electron-proton scattering
Y. Alanazi🇺🇸 · P. Ambrozewicz🇺🇸 · M. Battaglieri🇮🇹 · A. N. Hiller Blin🇩🇪 · M.P. Kuchera🇺🇸 · Y. Li🇺🇸 · T. Liu🇺🇸 · R.E. McClellan🇺🇸 · W. Melnitchouk🇺🇸 · E. Pritchard🇺🇸 · M. Robertson🇺🇸 · N. Sato🇺🇸 · R. Strauss🇺🇸 · L. Velasco
We present a new machine learning-based Monte Carlo event generator using generative adversarial networks (GANs) that can be trained with calibrated detector simulations to construct a vertex-level event generator free of theoretical assumptions about femtometer scale physics. Our framework includes a GAN-based detector folding as a fast-surrogate model that mimics detector simulators. The framework is tested and validated on simulated inclusive deep-inelastic scattering data along with existing parametrizations for detector simulation, with uncertainty quantification based on a statistical bootstrapping technique. Our results provide for the first time a realistic proof-of-concept to mitigate theory bias in inferring vertex-level event distributions needed to reconstruct physical observables.
↳ hep-phhep-exnucl-thPRD(2022)·29 citations
11
Fractal Structures of Yang-Mills Fields and Non Extensive Statistics: Applications to High Energy Physics
Airton Deppman🇧🇷 · Eugenio Megias🇪🇸 · Debora P. Menezes🇧🇷
In this work, we provide an overview of the recent investigations on the non-extensive Tsallis statistics and its applications to high energy physics and astrophysics, including physics at the Large Hadron Collider (LHC), hadron physics, and neutron stars. We review some recent investigations on the power-law distributions arising in high energy physics experiments focusing on a thermodynamic description of the system formed, which~could explain the power-law behavior. The possible connections with a fractal structure of hadrons is also discussed. The main objective of the present work is to delineate the state-of-the-art of those studies and~show some open issues that deserve more careful investigation. We propose several possibilities to test the theory through analyses of experimental data.
↳ hep-phhep-thnucl-thMDPI Physics(2020)·19 citations
12
Nuclear and dark matter heating in massive white dwarf stars
C. J. Horowitz🇺🇸
Recently, Cheng et al. identified a number of massive white dwarfs (WD) that appear to have an additional heat source providing a luminosity near $\approx 1 0^{- 3} L_{⊙}$ for multiple Gyr. In this paper we explore heating from electron capture and pycnonuclear reactions. We also explore heating from dark matter annihilation. WD stars appear to be too small to capture enough dark matter for this to be important. Finally, if dark matter condenses to very high densities inside a WD this could ignite nuclear reactions. We calculate the enhanced central density of a WD in the gravitational potential of a very dense dark matter core. While this might start a supernova, it seems unlikely to provide modest heating for a long time. We conclude that electron capture, pycnonuclear, and dark matter reactions are unlikely to provide significant heating in the massive WD that Cheng considers.
↳ astro-ph.SRastro-ph.HEhep-phnucl-thPRD(2020)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE