Nuclear Theory·nucl-th

Tuesday·November 20, 2018

28 papers—12 primary·16 cross-listed

01
[Submitted on 17 Nov 2018]
Sound velocity and tidal deformability in compact stars
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
The sound velocity $v_{s}$ and dimensionless tidal deformability $Λ$ are analyzed using the pseudo-conformal model we developed before. In contrast to the conclusion obtained in the previous works in the literature, our model with the upper bound of the sound velocity $v_{s} = 1/ 3$ , the so-called conformal sound velocity, set in at a { density relevant to compact stars} $\gsim 2 n_{0}$ where $n_{0}$ is the normal nuclear matter density, can accommodate {\it all} presently established nuclear matter and compact-star properties including the maximum star-mass constraint $≃ 2.3 M_{⊙}$ . This observation is associated with a possible emergence of pseudoconformal structure in compact star matter---in which the trace of energy-momentum tensor is a nearly density-independent nonzero constant---brought in by a topology change at $2.0 ≲ n_{1/2} / n_{0} ≲ 4.0$ commensurate with a possible change of degrees of freedom from hadrons.
Comments:
Version to appear in Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1811.07071 [pdf]
PRD(2019)·36 citations
02
[Submitted on 17 Nov 2018]
Nuclear electromagnetic dipole response with the Self-Consistent Green's Function formalism
F. Raimondi · C. Barbieri
Microscopic calculations of the electromagnetic response of medium-mass nuclei are now feasible thanks to the availability of realistic nuclear interactions with accurate saturation and spectroscopic properties, and the development of large-scale computing methods for many-body physics. The purpose is to compute isovector dipole electromagnetic (E1) response and related quantities, i.e. integrated dipole cross section and polarizability, and compare with data from photoabsorption and Coulomb excitation experiments. The single-particle propagator is obtained by solving the Dyson equation, where the self-energy includes correlations non-perturbatively through the Algebraic Diagrammatic Construction (ADC) method. The particle-hole ( $p h$ ) polarization propagator is treated in the Dressed Random Phase Approximation (DRPA), based on an effective correlated propagator that includes some $2 p 2 h$ effects but keeps the same computation scaling as the standard Hartree-Fock propagator. The E1 responses for $^{14, 16, 22, 24}$ O, $^{36, 40, 48, 52, 54, 70}$ Ca and $^{68}$ Ni have been computed: the presence of a soft dipole mode of excitation for neutron-rich nuclei is found, and there is a fair reproduction of the low-energy part of the experimental excitation spectrum. This is reflected in a good agreement with the empirical dipole polarizability values. For a realistic interaction with an accurate reproduction of masses and radii up to medium-mass nuclei, the Self-Consistent Green's Function method provides a good description of the E1 response, especially in the part of the excitation spectrum below the Giant Dipole Resonance. The dipole polarizability is largely independent from the strategy of mapping the dressed propagator to a simplified one that is computationally manageable
Comments:
14 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.07163 [pdf]
PRC(2019)·40 citations
03
[Submitted on 17 Nov 2018]
Deconfinement of non-strange hadronic matter with nucleons and $Δ$ baryons to quark matter in neutron stars
Debashree Sen🇮🇳 · T.K. Jha🇮🇳
We explore the possibility of formation of $Δ$ baryons (1232 MeV) in neutron star matter in an effective chiral model within the relativistic mean-field framework. With variation in delta-meson couplings, consistent with the constraints imposed on them, the resulting equation of state is obtained and the neutron star properties are calculated for static and spherical configuration. Within the framework of our model the critical densities of formation of $Δ$ s and the properties of neutron stars are found to be very sensitive to the iso-vector coupling compared to the scalar or vector couplings. We revisit the $Δ$ puzzle and look for the possibility of phase transition from non-strange hadronic matter (including nucleons and $Δ$ s) to deconfined quark matter, based on QCD theories. The resultant hybrid star configurations satisfy the observational constraints on mass from the most massive pulsars PSR J1614-2230 and PSR J0348+0432 in static condition obtained with the general hydrostatic equilibrium based on GTR. Our radius estimates are well within the limits imposed from observational analysis of QLMBXs. The obtained values of $R_{1.4}$ are in agreement with the recent bounds specified from the observation of gravitational wave (GW170817)from binary neutron star merger. The constraint on baryonic mass from study of binary system PSR J0737-3039 is also satisfied with our hybrid equation of state. \noindent{Keywords: Delta baryons, Quark matter, Phase transition, Equation of State, Neutron Stars, Hybrid Stars}
Comments:
30 pages, 19 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1811.07227 [pdf]
Int.J.Mod.Phys.D(2018)·12 citations
04
[Submitted on 18 Nov 2018]
Possible signals of two QCD phase transitions at NICA-FAIR energies
K. A. Bugaev🇺🇦 · A. I. Ivanytskyi🇺🇦 · V. V. Sagun🇺🇦 · B. E. Grinyuk🇺🇦 · D. O. Savchenko🇺🇦 · G. M. Zinovjev🇺🇦 · E. G. Nikonov🇷🇺 · L. V. Bravina🇳🇴 · E. E. Zabrodin🇷🇺 · D. B. Blaschke🇷🇺 · S. Kabana🇫🇷 · A. V. Taranenko🇷🇺
The chemical freeze-out irregularities found with the most advanced hadron resonance gas model and possible signals of two QCD phase transitions are discussed. We found that the center-of-mass collision energy range of tricritical endpoint of QCD phase diagram is [9; 9.2] GeV which is consistent both with QCD inspired exactly solvable model and with experimental findings.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.07420 [pdf]
EPJ Web Conf.(2019)·6 citations
05
[Submitted on 19 Nov 2018]
Effects of hadron-quark phase transition on properties of Neutron Stars
Debashree Sen🇮🇳 · T.K. Jha🇮🇳
We investigate the possible scenario of deconfinement of hyperon rich hadronic matter to quark matter at high densities and the resulting hybrid star (HS) properties are analyzed. In the relativistic mean-field framework, we construct the equation of state (EoS) of hadronic matter using the effective chiral model while the pure quark matter is described using the MIT Bag model. We revisit the hyperon puzzle and analyze the possibility of hadron-quark phase transition with proper choice of the bag constant. In static condition the maximum mass of the resultant HSs are in good agreement with the recent observational bounds on the same from high mass pulsars such as PSR J1614-2230 and PSR J0348+0432. On invoking the phenomenon of phase transition, the radius of canonical mass ( $R_{1.4}$ ) and value of $R_{1.6}$ predicted by the model lie within the range prescribed from binary neutron star (BNS) merger detected by the LIGO-Virgo collaboration in 2017. The surface redshift obtained for the HSs also satisfy the constraints from pulsars RX J0720.4-3125 and 1E 1207.4-5209. It is noteworthy that unlike several other works, we add no modifications to the original form of the Bag model to satisfy these recent observational and empirical constraints on NS properties. We also discuss the rotational aspects of the HSs by calculating the properties like rotational mass, radius, energy density, moment of inertia at different angular velocities. The maximum bound on rotational frequency from the rapidly rotating pulsars like PSR B1937+21 and PSR J1748-2446ad are satisfied with the HS configuration. We also test the universality of our hybrid EoS in terms of normalized moment of inertia.
Comments:
28 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1811.07434 [pdf]
J.Phys.G(2019)·25 citations
06
[Submitted on 19 Nov 2018]
Quarkonium dissociation in perturbative QCD
Juhee Hong🇰🇷 · Su Houng Lee🇰🇷
For weakly bound quarkonia, we rederive the next-to-leading order cross sections of quarkonium dissociation by partons that include the hard thermal loop (HTL) resummation. Our results calculated with an effective vertex from the Bethe-Salpeter amplitude reduce to those obtained by potential nonrelativistic QCD (pNRQCD) in the relevant kinematical limit, and they can be used in a wide temperature range applicable to heavy quark systems in heavy ion collisions. Based on the lattice computation of the temperature-dependent binding energy, our numerical analysis on $Υ (1 S)$ indicates that at high temperature the dominant mechanism for quarkonium dissociation is inelastic parton scattering as expected in the quasifree approximation, while it is the gluo-dissociation at low temperature. By comparing with the momentum diffusion coefficient of a heavy quark, we discuss possible O(g) corrections to the next-to-leading order thermal width.
Comments:
18 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1811.07607 [pdf]
PRC(2019)·8 citations
07
[Submitted on 19 Nov 2018]
$S$ -factor and scattering parameters from $^{3}$ He + $^{4}$ He $\to^{7}$ Be + $γ$ data
Xilin Zhang · Kenneth M. Nollett · Daniel R. Phillips
We use the next-to-leading-order (NLO) amplitude in an effective field theory (EFT) for $^{3}$ He + $^{4}$ He $\to^{7}$ Be + $γ$ to perform the extrapolation of higher-energy data to solar energies. At this order the EFT describes the capture process using an s-wave scattering length and effective range, the asymptotic behavior of $^{7}$ Be and its excited state, and short-distance contributions to the E1 capture amplitude. We use a Bayesian analysis to infer the multi-dimensional posterior of these parameters from capture data below 2 MeV. The total $S$ -factor $S (0) = 0.57 8_{- 0.016}^{+ 0.015}$ keV b at 68% degree of belief. We also find significant constraints on $^{3}$ He- $^{4}$ He scattering parameters.
Comments:
4 pages, 2 figures. Submitted to the proceedings of the 22nd International Conference on Few-body Problems in Physics, Caen, France, July 9-13, 2018. Uses svproc.cls
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1811.07611 [pdf]
Springer Proc.Phys.(2020)·6 citations
08
[Submitted on 19 Nov 2018]
Deep-inelastic and quasielastic electron scattering from $A = 3$ nuclei
A. J. Tropiano🇺🇸 · J. J. Ethier🇳🇱 · W. Melnitchouk🇺🇸 · N. Sato🇺🇸
We perform a combined analysis of inclusive electron scattering data from $A = 3$ nuclei in the deep-inelastic and quasielastic scattering regions, using Monte Carlo analysis methods and the nuclear weak binding approximation to establish the range over which the data can be described within the same theoretical framework. Comparison with quasielastic $^{3}$ He cross sections from SLAC and Jefferson Lab suggests that most features of the $x ≳ 1$ data can be reasonably well described in the impulse approximation with finite- $Q^{2}$ nuclear smearing functions for momentum transfers $Q^{2} ≳ 1$ GeV $^{2}$ . For the DIS region, we analyze the recent $^{3}$ He to deuterium cross section ratio from the Jefferson Lab E03-103 experiment to explore the possible isospin dependence of the nuclear effects. We discuss the implications of this for the MARATHON experiment at Jefferson Lab, and outline how a Bayesian analysis of $^{3}$ He, $^{3}$ H and deuterium data can robustly determine the free neutron structure function.
Comments:
45 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1811.07668 [pdf]
PRC(2019)·19 citations
09
[Submitted on 19 Nov 2018]
Fine structure of the pygmy quadrupole resonance in $^{112, 114}$ Sn isotopes
N. Tsoneva · M. Spieker · H. Lenske · A. Zilges
The electric quadrupole response in $^{112, 114}$ Sn isotopes is investigated by energy-density functional (EDF) and three-phonon quasiparticle-phonon model (QPM) theory with special emphasis on 2 $^{+}$ excitations located above the first collective quadrupole state and below 5 MeV. Additional quadrupole strength clustering as a sequence of states similar to the recently observed pygmy quadrupole resonance in $^{124}$ Sn is found. The spectral distributions and transition densities of these 2 $^{+}$ states show special features being compatible with oscillations of a neutron skin against the isospin-symmetric nuclear core. Furthermore, two new ( $p$ , $p^{'} γ$ ) Doppler-shift attenuation (DSA) coincidence experiments were performed at the SONIC@HORUS setup. Quadrupole states with excitation energies up to 4.2 MeV were populated in $^{112, 114}$ Sn. Lifetimes and branching ratios were measured allowing for the determination of the reduced quadrupole transition strengths to the ground state. A stringent comparison of the new data to EDF+QPM theory in $^{112}$ Sn and $^{114}$ Sn isotopes hints at the occurrence of a low-energy quadrupole mode of unique character which could be interpreted as pygmy quadrupole resonance.
Comments:
6 pages, 4 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.07739 [pdf]
NPA(2019)·15 citations
10
[Submitted on 19 Nov 2018]
Elucidating the multiplicity dependence of J/ $ψ$ production in proton-proton collisions with PYTHIA8
S. G. Weber🇩🇪 · A. Dubla🇩🇪 · A. Andronic🇩🇪 · A. Morsch🇨🇭
A study of prompt and non-prompt J/ $ψ$ production as a function of charged-particle multiplicity in inelastic proton--proton (pp) collisions at a centre-of-mass energy of $s$ = 13 TeV based on calculations using the PYTHIA8 Monte Carlo is reported. Recent experimental data shows an intriguing stronger-than-linear increase of the self-normalized J/ $ψ$ yield with multiplicity; several models, based on initial or final state effects, have been able to describe the observed behaviour. In this paper, the microscopic reasons for this behaviour, like the role of multiple parton interactions, colour reconnections and auto-correlations are investigated. It is observed that the stronger-than-linear increase and the transverse momentum ( $p_{T}$ ) dependence, contrary to what is predicted by the other available models, can be attributed to auto-correlation effects only. In absence of auto-correlation effects, the increase of the yield of J/ $ψ$ with multiplicity -- and in general for all hard processes -- is weaker than linear for multiplicities exceeding about three times the mean multiplicity. The possibility of disentangling auto-correlation effects from other physical phenomena by measuring the charged-particle multiplicity in different pseudo-rapidity and azimuthal regions relative to the J/ $ψ$ direction is investigated. In this regard, it is suggested to extend the experimental measurements of J/ $ψ$ production as a function of the charged-particle multiplicity by determining the multiplicity in several azimuthal regions and in particular in the Transverse region with respect to the direction of the J/ $ψ$ meson.
Comments:
12 pages, 14 figures: accepted by EPJC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1811.07744 [pdf]
EPJC(2019)·61 citations
11
[Submitted on 19 Nov 2018]
The QCD Phase Diagram from Statistical Model Analysis
Reinhard Stock · Francesco Becattini · Marcus Bleicher · Jan Steinheimer
In high multiplicity nucleus-nucleus collisions baryon-antibaryon annihilation and regeneration occur during the final hadronic expansion phase, thus distorting the initial equilibrium multiplicity ratios. We quantify the modifications employing the hybrid UrQMD transport model and apply them to the grand canonical partition functions of the Statistical Hadronization Model(SHM). We analyze minimum bias and central Pb+Pb collision data at SPS and LHC energy. We explain the Pion to Proton ratio puzzle. We also reproduce the deuteron to proton ratio at LHC energy by the SHM, and by UrQMD after attaching a phase space coalescence process. We discuss the resulting (T, $μ_{B}$ ) diagram.
Comments:
Quark Matter 2018 proceedings. Talk presented by Reinhard Stock. Accepted version
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1811.07766 [pdf]
NPA(2019)·9 citations
12
[Submitted on 19 Nov 2018]
Error analysis of the parameters of the Skyrme N2LO pseudo-potential
P. Becker🇬🇧 · A. Pastore🇬🇧 · D. Davesne🇫🇷 · J. Navarro🇪🇸
We perform a detailed analysis of the parameters of the Skyrme SN2LO interaction. By mean of a covariance matrix analysis, we have been able to provide error bars and build the complete covariance matrix. The latter will be used in future applications to properly study the propagation of errors on nuclear observables calculated with this pseudo-potential.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.07866 [pdf]
Nuovo Cim.C(2019)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE