Nuclear Theory·nucl-th

Tuesday·January 29, 2019

20 papers—11 primary·9 cross-listed

01
Transverse momentum distributions of charmonium states with the statistical hadronization model
Anton Andronic🇩🇪 · Peter Braun-Munzinger🇩🇪 · Markus K. Köhler🇩🇪 · Krzysztof Redlich🇩🇪 · Johanna Stachel🇩🇪
Calculations and predictions are presented within the framework of the statistical hadronization model for transverse momentum spectra of the charmonium states J/ $ψ$ , $ψ (2 S)$ and $X (3872)$ produced in nucleus-nucleus collisions at LHC energies. The results are confronted with available data and exhibit very good agreement by using particle flow profiles from state-of-the-art hydrodynamic calculations. For $X (3872)$ production in Pb-Pb collisions we predict a transverse momentum distribution similar in shape to that for J/ $ψ$ with a strong enhancement at low transverse momenta and a production yield of about 1\% relative to that for J/ $ψ$ .
nucl-thPLB(2019)·139 citations
02
Theoretical Review of Charmonium Production with Different $p_{T}$ in the Hot Medium
Baoyi Chen · Carsten Greiner🇩🇪
Charmonia with different transverse momentum $p_{T}$ usually comes from different mechanisms in the relativistic heavy ion collisions. This work tries to review the theoretical studies on quarkonium evolutions in the deconfined medium produced in p-Pb and Pb-Pb collisions. The charmonia with high $p_{T}$ are mainly from the initial hadronic collisions, and therefore sensitive to the initial energy density of the bulk medium. For those charmonia within $0.1 < p_{T} < 5$ GeV/c at the energies of Large Hadron Collisions (LHC), They are mainly produced by the recombination of charm and anti-charm quarks in the medium. In the extremely low $p_{T} \sim 1/ R_{A}$ ( $R_{A}$ is the nuclear radius), additional contribution from the coherent interactions between electromagnetic fields generated by one nucleus and the target nucleus plays a non-negligible role in the $J / ψ$ production even in semi-central Pb-Pb collisions.
nucl-thhep-phEPJ Web Conf.(2019)·1 citation
03
Probing nuclear bubble configuration by proton induced reaction
Xiao-Hua Fan🇨🇳 · Gao-Chan Yong🇨🇳 · Wei Zuo🇨🇳
In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, nuclear bubble configuration in the hypothetical $^{48}$ Si nucleus is studied by proton induced central reaction at an incident beam energy of 0.8 GeV/nucleon. It is found that along the beam direction more energetic protons are emitted with bubble configuration in the target. In the forward angles, compared with the case without bubble configuration, less scattered energetic protons are emitted with bubble configuration in the target. We thus provide a new way to probe the bubble configuration in nuclei.
nucl-thnucl-exPRC(2019)·16 citations
04
Forward and backward comparative study of jet properties in pp collisions at \sqrt{s}=7 TeV
Yu-Liang Yan🇨🇳 · Ayut Limphirat🇹🇭 · Dai-Mei Zhou🇨🇳 · Pornrad Srisawad🇹🇭 · Yupeng Yan🇹🇭 · Chunbin Yang🇨🇳 · Xu Cai🇨🇳 · Ben-Hao Sa🇨🇳
We propose a forward method, based on the PYTHIA6.4, to study theoretically the jet properties in the ultra-relativistic pp collisions. In the forward method, the partonic initial states are first generated with PYTHIA6.4 and then hadronized in the Lund srting fragmentation regime, and finally hadronic jets are constructed from the created hadrons. Jet properties calculated in the forward method for pp collisions at \sqrt{s}=7 TeV are comparable with the corresponding ones calculated with usual anti-k_t algorithm (backward method) in the PYTHIA6.4. The comparison between the results in the backward and forward methods may bring benefit to the understanding of the partonic origin of jets in the backward method.
nucl-thhep-phCPC(2020)·0 citations
05
Impact of different extended components of mean field models on transport coefficients of quark matter and their causal aspects
Chowdhury Aminul Islam🇮🇳 · Jayanta Dey🇮🇳 · Sabyasachi Ghosh🇮🇳
Role of different extensions of Nambu\textendash Jona-Lasinio (NJL) model like addition of vector interaction, Polyakov loop extended version (PNJL) and the entangled PNJL (EPNJL) models on transport coefficients like shear viscosity, bulk viscosity, electrical conductivity and thermal conductivity are critically analyzed. We have considered the standard expressions of transport coefficients, obtained in relaxation time approximation of kinetic theory. Influence of temperature dependent order parameters on temperature profile of transport coefficients are analyzed. Causal aspect of massless case to these different extended components of mean field models are also picturized, where an approximated lower and upper bound are drawn for shear relaxation time.
nucl-thhep-phPRC(2021)·15 citations
06
Folding model analysis of $^{12} C -^{12} C$ and $^{16} O -^{16} O$ elastic scattering using the density-dependent LOCV averaged effective interaction
M. Rahmat · M. Modarres
The averaged effective two-body interaction (\textit{AEI}) which can be generated through the lowest order constrained variational (\textit{LOCV}) method for symmetric nuclear matter (\textit{SNM}) with the input \textit{Reid}68 nucleon-nucleon potential, is used as the effective nucleon-nucleon potential in the folding model to describe the heavy-ion (\textit{HI}) elastic scattering cross sections. The elastic scattering cross sections of $^{12} C -^{12} C$ and $^{16} O -^{16} O$ systems are calculated in the above frameworks. The results are compared with the corresponding calculations coming from the fitting procedures with the input finite range \textit{DDM3Y1-Reid} potential and the available experimental data at different incident energies. It is shown that a reasonable description of the elastic $^{12} C -^{12} C$ and $^{16} O -^{16} O$ scattering data at the low and the medium energies can be obtained by using the above \textit{ LOCV AEI}, without any need to define a parameterize density dependent function in the effective nucleon-nucleon potential, which is formally considered in the typical \textit{DDM3Y1-Reid} interactions.
nucl-thPRC(2018)·7 citations
07
Charmed nuclei within a microscopic many-body approach
I. Vidana🇮🇹 · A. Ramos🇪🇸 · C. E. Jimenez-Tejero🇪🇸
Single-particle energies of the $Λ_{c}$ chamed baryon are obtained in several nuclei from the relevant self-energy constructed within the framework of a perturbative many-body approach. Results are presented for a charmed baryon-nucleon ( $Y_{c} N$ ) potential based on a SU(4) extension of the meson-exchange hyperon-nucleon potential $A ~$ of the Jülich group. Three different models (A, B and C) of this interaction, that differ only on the values of the couplings of the scalar $σ$ meson with the charmed baryons, are considered. Phase shifts, scattering lengths and effective ranges are computed for the three models and compared with those predicted by the $Y_{c} N$ interaction derived in Eur. Phys. A {\bf 54}, 199 (2018) from the extrapolation to the physical pion mass of recent results of the HAL QCD Collaboration. Qualitative agreement is found for two of the models (B and C) considered. Our results for $Λ_{c}$ -nuclei are compatible with those obtained by other authors based on different models and methods. We find a small spin-orbit splitting of the $p -, d -$ and $f -$ wave states as in the case of single $Λ$ -hypernuclei. The level spacing of $Λ_{c}$ single-particle energies is found to be smaller than that of the corresponding one for hypernuclei. The role of the Coulomb potential and the effect of the coupling of the $Λ_{c} N$ and $Σ_{c} N$ channels on the single-particle properties of $Λ_{c} -$ nuclei are also analyzed. Our results show that, despite the Coulomb repulsion between the $Λ_{c}$ and the protons, even the less attractive one of our $Y_{c} N$ models (model C) is able to bind the $Λ_{c}$ in all the nuclei considered. The effect of the $Λ_{c} N - Σ_{c} N$ coupling is found to be almost negligible due to the large mass difference of the $Λ_{c}$ and $Σ_{c}$ baryons.
nucl-thhep-phnucl-exPRC(2019)·16 citations
08
The APR equation of state for simulations of supernovae, neutron stars and binary mergers
A. S. Schneider🇸🇪 · C. Constantinou🇺🇸 · B. Muccioli🇺🇸 · M. Prakash🇺🇸
Differences in the equation of state (EOS) of dense matter translate into differences in astrophysical simulations and their multi-messenger signatures. Thus, extending the number of EOSs for astrophysical simulations allows us to probe the effect of different aspects of the EOS in astrophysical phenomena. In this work, we construct the EOS of hot and dense matter based on the Akmal, Pandharipande, and Ravenhall (APR) model and thereby extend the open-source SROEOS code which computes EOSs of hot dense matter for Skyrme-type parametrizations of the nuclear forces. Unlike Skrme-type models, in which parameters of the interaction are fit to reproduce the energy density of nuclear matter and/or properties of heavy nuclei, the EOS of APR is obtained from potentials resulting from fits to nucleon-nucleon scattering and properties of light nuclei. In addition, this EOS features a phase transition to a neutral pion condensate at supra-nuclear densities. We show that differences in the effective masses between EOSs have consequences for the properties of nuclei in the sub-nuclear inhomogeneous phase of matter. We also test the new EOS of APR in spherically symmetric core-collapse of massive stars with $15 M_{⊙}$ and $40 M_{⊙}$ , respectively. We find that the phase transition in the EOS of APR speeds up the collapse of the star. However, this phase transition does not generate a second shock wave or another neutrino burst as reported for the hadron-to-quark phase transition. The reason for this difference is that the onset of the phase transition in the EOS of APR occurs at larger densities than for the quark-to-hadron transition employed earlier which results in a significantly smaller softening of the high density EOS.
nucl-thastro-ph.HEPRC(2019)·91 citations
09
Single pole dominance in short- and intermediate-range $N N$ interaction
V.I. Kukulin · V.N. Pomerantsev · O.A. Rubtsova · M.N. Platonova
It is demonstrated that both elastic and inelastic $N N$ scattering at laboratory energies up to 600--800 MeV, at least in some partial waves characterized by a large inelasticity, can be described by a superposition of the conventional long-range one-pion exchange and a specific short-range interaction induced by the $s$ -channel dibaryon exchange. For the $^{3} P_{2}$ , $^{1} D_{2}$ and $^{3} F_{3}$ partial waves, the pole parameters giving the best fit of the real and imaginary parts of the $N N$ phase shifts are consistent with the parameters of the respective isovector dibaryon resonances found experimentally. In the $^{1} S_{0}$ channel, the suggested interaction gives two poles of the $S$ -matrix -- the well-known singlet deuteron and an excited dibaryon. On the basis of the results presented, a conclusion is made about the nature of $N N$ interaction and its strong channel dependence.
nucl-th2 citations
10
Theoretical exploration of $S$ -factors for nuclear reactions of astrophysical importance
Vinay Singh · Joydev Lahiri · D. N. Basu
We present here a robust analytical model based on nuclear reaction theory for non-resonant fusion cross sections near Coulomb barrier. The astrophysical $S$ -factors involving stable and neutron rich isotopes of C, O, Ne, Mg and Si for fusion reactions have been calculated in the centre of mass energy range of 2-30 MeV. The model is based on the tunneling through barrier arising out of nuclear, Coulomb and centrifugal potentials. Our formalism predicts precisely the suppression of $S$ -factor at sub-barrier energies which are of astrophysical interest. The cross sections can be convoluted with Maxwell-Boltzmann distribution of energies to obtain thermo- or pycno- nuclear reaction rates relevant to nucleosynthesis at high density environments and stellar burning at high temperatures as well as for $^{34}$ Ne $+$ $^{34}$ Ne fusion occurring in the inner crust of accreting neutron stars.
nucl-thNPA(2019)·6 citations
11
Confronting gravitational-wave observations with modern nuclear physics constraints
I. Tews🇺🇸 · J. Margueron🇫🇷 · S. Reddy🇺🇸
Multi-messenger observations of neutron star (NS) mergers have the potential to revolutionize nuclear astrophysics. They will improve our understanding of nucleosynthesis, provide insights about the equation of state (EOS) of strongly-interacting matter at high densities, and enable tests of the theory of gravity and of dark matter. Here, we focus on the EOS, where both gravitational waves (GWs) from neutron-star mergers and X-ray observations from space-based detectors such as NICER will provide more stringent constraints on the structure of neutron stars. Furthermore, recent advances in nuclear theory have enabled reliable calculations of the EOS at low densities using effective field theory based Hamiltonians and advanced techniques to solve the quantum many-body problem. In this paper, we address how the first observation of GWs from GW170817 can be combined with modern calculations of the EOS to extract useful insights about the EOS of matter encountered inside neutron stars. We analyze the impact of various uncertainties, the role of phase transitions in the NS core, and discuss how future observations will improve our understanding of dense matter.
nucl-thastro-ph.HEhep-phEPJA(2019)·113 citations

Affiliations

first authorsco-authorsvia INSPIRE