Nuclear Theory·nucl-th

Wednesday·November 23, 2016

16 papers—9 primary·7 cross-listed

01
Effects of Induced Surface Tension in Nuclear and Hadron Matter
V.V. Sagun🇺🇦 · K.A. Bugaiev🇺🇦 · A.I. Ivanytskyi🇺🇦 · D.R. Oliinychenko🇺🇦 · I.N. Mishustin🇩🇪
Short range particle repulsion is rather important property of the hadronic and nuclear matter equations of state. We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard-core repulsion. In addition to the hard-core repulsion taken into account by the proper volumes of particles, this equation of state explicitly contains the surface tension which is induced by another part of the hard-core repulsion between particles. At high densities the induced surface tension vanishes and the excluded volume treatment of hard-core repulsion is switched to its proper volume treatment. Possible applications of this equation of state to a description of hadronic multiplicities measured in A+A collisions, to an investigation of the nuclear matter phase diagram properties and to the neutron star interior modeling are discussed.
nucl-thastro-ph.HEhep-phEPJ Web Conf.(2017)·13 citations
02
Symmetry Parameter Constraints From A Lower Bound On The Neutron-Matter Energy
Ingo Tews🇺🇸 · James M. Lattimer🇺🇸 · Akira Ohnishi🇯🇵 · Evgeni E. Kolomeitsev🇸🇰
We propose the existence of a lower bound on the energy of pure neutron matter (PNM) on the basis of unitary-gas considerations. We discuss its justification from experimental studies of cold atoms as well as from theoretical studies of neutron matter. We demonstrate that this bound results in limits to the density-dependent symmetry energy, which is the difference between the energies of symmetric nuclear matter and PNM. In particular, this bound leads to a lower limit to the volume symmetry energy parameter $S_{0}$ . In addition, for assumed values of $S_{0}$ above this minimum, this bound implies both upper and lower limits to the symmetry energy slope parameter $L$ , which describes the lowest-order density dependence of the symmetry energy. A lower bound on the neutron-matter incompressibility is also obtained. These bounds are found to be consistent with both recent calculations of the energies of PNM and constraints from nuclear experiments. Our results are significant because several equations of state that are currently used in astrophysical simulations of supernovae and neutron star mergers, as well as in nuclear physics simulations of heavy-ion collisions, have symmetry energy parameters that violate these bounds. Furthermore, below the nuclear saturation density, the bound on neutron-matter energies leads to a lower limit to the density-dependent symmetry energy, which leads to upper limits to the nuclear surface symmetry parameter and the neutron-star crust-core boundary. We also obtain a lower limit to the neutron-skin thicknesses of neutron-rich nuclei. Above the nuclear saturation density, the bound on neutron-matter energies also leads to an upper limit to the symmetry energy, with implications for neutron-star cooling via the direct Urca process.
nucl-thastro-ph.HEcond-mat.quant-gasApJ(2017)·319 citations
03
Lepton production cross sections in quasielastic $ν / ν ˉ -$ A scattering
M. Sajjad Athar🇮🇳 · F. Akbar🇮🇳 · M. Rafi Alam🇮🇳 · S. Chauhan🇮🇳 · S. K. Singh🇮🇳 · F. Zaidi🇮🇳
We present the results of (anti)neutrino induced CCQE cross sections from some nuclear targets in the energy region of $E_{ν} \leq 1 G e V$ . The aim of the study is to confront electron and muon production cross sections relevant for $ν_{μ} \leftrightarrow ν_{e}$ or $ν ˉ_{μ} \leftrightarrow ν ˉ_{e}$ oscillation experiments. The effects due to lepton mass and its kinematic implications, second class currents and uncertainties in the axial and pseudoscalar form factors are discussed for (anti)neutrino induced reaction cross sections on free nucleon as well as the nucleons bound in a nucleus where nuclear medium effects influence the cross section. The calculations have been performed using local Fermi gas model with nucleon correlation effects. The details are given in Ref.[1].
nucl-th2 citations
04
Medium effects in the deep-inelastic charged lepton/neutrino-A scattering
H. Haider🇮🇳 · F. Zaidi🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳 · I. Ruiz Simo🇪🇸
In this work, we have discussed the recent developments that have taken place to understand the differences in the weak $F_{2 A}^{W e ak} (x, Q^{2})$ and electromagnetic $F_{2 A}^{E M} (x, Q^{2})$ nuclear structure functions. Also we present the results of our work on nuclear medium effects on $F_{2 A}^{W e ak} (x, Q^{2})$ and $F_{2 A}^{E M} (x, Q^{2})$ for a wide range of $x$ and $Q^{2}$ . These results have been obtained using a microscopic nuclear model, where to incorporate nuclear medium effects, Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects are considered. The calculations are performed in local density approximation using relativistic nucleon spectral function. We have also compared the theoretical results with the recent experimental data on electromagnetic and weak structure functions. Furthermore, we have studied the nuclear medium effects in Drell-Yan(DY) process and present the results for differential cross section, and the results are compared with the data of E772 experiment.
nucl-th0 citations
05
Forward-backward correlations between intensive observables
Vladimir Kovalenko🇷🇺 · Vladimir Vechernin (Saint Petersburg State University, Russia)🇷🇺
We demonstrate that the investigations of the forward-backward correlations between intensive observables enable to obtain more clear signal about the initial stage of hadronic interaction, e.g. about the process of string fusion, compared to usual forward-backward multiplicity correlations. As an example, the correlation between mean-event transverse momenta of charged particles in separated rapidity intervals is considered. We performed calculations in the framework of dipole-based Monte Carlo string fusion model. We obtained the dependence of the correlation strength on the collision centrality for different initial energies and colliding systems. It is shown that the dependence reveals the decline of the correlation coefficient for most central Pb-Pb collisions at LHC energy. We compare the results both with the ones obtained in alternative models and with the ones obtained by us using various MC generators.
nucl-thhep-phJ.Phys.Conf.Ser.(2017)·12 citations
06
Hadron Resonance Gas Model for An Arbitrarily Large Number of Different Hard-Core Radii
K. A. Bugaev · V. V. Sagun · A. I. Ivanytskyi · I. P. Yakimenko · E. G. Nikonov · A.V. Taranenko · G. M. Zinovjev
We develop a novel formulation of the hadron-resonance gas model which, besides a hard-core repulsion, explicitly accounts for the surface tension induced by the interaction between the particles. Such an equation of state allows us to go beyond the Van der Waals approximation for any number of different hard-core radii. A comparison with the Carnahan-Starling equation of state shows that the new model is valid for packing fractions 0.2-0.22, while the usual Van der Waals model is inapplicable at packing fractions above 0.1-0.11. Moreover, it is shown that the equation of state with induced surface tension is softer than the one of hard spheres and remains causal at higher particle densities. The great advantage of our model is that there are only two equations to be solved and it does not depend on the various values of the hard-core radii used for different hadronic resonances. Using this novel equation of state we obtain a high-quality fit of the ALICE hadron multiplicities measured at center-of-mass energies of 2.76 TeV per nucleon. Furthermore, using the traditional hadron-resonance gas model with multi-component hard-core repulsion and the novel one we investigate the recently suggested model in which the proper volume of a hadron is proportional to its mass. We find that the high-temperature maximum of $χ^{2} / n df$ observed in the latter model always appears in the region located far above the limit of its applicability.
nucl-thhep-ph7 citations
07
The Peak Structure in the In-Flight $^{3} He (K^{-}, Λ p) n$ Reaction Around the $K ˉ N N$ Threshold
Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. amd Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U. and ICC, Barcelona U.)🇪🇸
We theoretically investigate the origin of the peak structure around the $K^{-} pp$ threshold observed in the in-flight $^{3} He (K^{-}, Λ p) n$ reaction in the recent E15 experiment at J-PARC. For this purpose, we consider two scenarios to produce the peak. One is that the $Λ (1405)$ is generated but it does not correlate with $p$ , and the uncorrelated $Λ (1405) p$ system subsequently decays into $Λ p$ . The other one is that the $K ˉ N N$ bound state is indeed generated and decays into $Λ p$ . As a result, the experimental signal is qualitatively well reproduced in the $K ˉ N N$ bound scenario, definitely discarding the uncorrelated $Λ (1405) p$ one.
nucl-thhep-phnucl-exJPS Conf.Proc.(2017)·2 citations
08
Leading Neutrons From Polarized Proton-Nucleus Collisions
B. Z. Kopeliovich🇨🇱 · I. K. Potashnikova🇨🇱 · Ivan Schmidt🇨🇱
Leading neutron production on protons is known to be subject to strong absorptive corrections, which have been under debate for a long time. On nuclear targets these corrections are significantly enhanced and push the partial cross sections of neutron production to the very periphery of the nucleus. As a result, the A-dependences of inclusive and diffractive neutron production turn out to be similar. The mechanism of \pi-a_1 interference, which successfully explained the observed single-spin asymmetry of neutrons in polarized pp interactions, is extended here to polarized pA collisions. Corrected for nuclear effects it explains well the magnitude and sign of the asymmetry A_N observed in inelastic events, resulting in a violent break up of the nucleus. However the excessive magnitude of A_N observed in the diffractive sample, remains a challenge.
nucl-thhep-phAIP Conf.Proc.(2017)·4 citations
09
On the Origin of the Elliptic Flow and its Dependence on the Equation of State in Heavy Ion Reactions at Intermediate Energies
A. Le Fevre🇩🇪 · Y. Leifels🇩🇪 · C. Hartnack🇫🇷 · J. Aichelin🇫🇷
Recently it has been discovered that the elliptic flow, v2, of composite charged particles emitted at midrapidity in Heavy-Ion collisions at intermediate energies shows the strongest sensitivity to the Nuclear Equation of State (EoS) which has been observed up to now within a microscopic model. This dependence on the nuclear EoS is predicted by Quantum Molecular Dynamics (QMD) calculations [1] which show as well that the absorption or rescattering of in-plane emitted particles by the spectator matter is not the main reason for the EoS dependence of the elliptic flow at mid-rapidity but different density gradients (and therefore different forces) in the direction of the impact parameter (x-direction) as compared to the direction perpendicular to the reaction plan (y-direction), caused by the presence of the spectator matter. The stronger density gradient in y-direction accelerates the particles more and creates therefore a negative v2. When using a soft momentum dependent EoS, the QMD calculations reproduce the experimental results.
nucl-thPRC(2018)·57 citations
10
Neutral Weak Form Factors of Proton and Neutron
Raza Sabbir Sufian🇺🇸
We determine the nucleon neutral weak electromagnetic form factors $G_{E, M}^{Z, p (n)}$ by combining results from light-front holographic QCD and lattice QCD calculations. We deduce nucleon electromagnetic form factors from light-front holographic QCD which provides a good parametrization of the experimental data of the nucleon electromagnetic form factors in the entire momentum transfer range and isolate the strange quark electromagnetic form factors $G_{E, M}^{s}$ using lattice QCD. From these calculations, we obtain precise estimates of the neutral weak form factors in the momentum transfer range of $0 GeV^{2} \leq Q^{2} \leq 0.5 GeV^{2}$ . From the lattice QCD calculation, we present $Q^{2}$ -dependence of the strange quark form factors. We also deduce the neutral weak Dirac and Pauli form factors $F_{1, 2}^{Z, p (n)}$ of the proton and the neutron.
↳ hep-phhep-latnucl-thPRD(2017)·10 citations
11
Second-order transport, quasinormal modes and zero-viscosity limit in the Gauss-Bonnet holographic fluid
Sašo Grozdanov🇳🇱 · Andrei O. Starinets🇬🇧
Gauss-Bonnet holographic fluid is a useful theoretical laboratory to study the effects of curvature-squared terms in the dual gravity action on transport coefficients, quasinormal spectra and the analytic structure of thermal correlators at strong coupling. To understand the behavior and possible pathologies of the Gauss-Bonnet fluid in $3 + 1$ dimensions, we compute (analytically and non-perturbatively in the Gauss-Bonnet coupling) its second-order transport coefficients, the retarded two- and three-point correlation functions of the energy-momentum tensor in the hydrodynamic regime as well as the relevant quasinormal spectrum. The Haack-Yarom universal relation among the second-order transport coefficients is violated at second order in the Gauss-Bonnet coupling. In the zero-viscosity limit, the holographic fluid still produces entropy, while the momentum diffusion and the sound attenuation are suppressed at all orders in the hydrodynamic expansion. By adding higher-derivative electromagnetic field terms to the action, we also compute corrections to charge diffusion and identify the non-perturbative parameter regime in which the charge diffusion constant vanishes.
↳ hep-thcond-mat.str-elgr-qcnucl-thJHEP(2017)·106 citations
12
Electric dipole polarizability of $^{48}$ Ca and implications for the neutron skin
J. Birkhan (1) · M. Miorelli (2,3) · S. Bacca (2,4) · S. Bassauer (1) · C.A. Bertulani (5) · G. Hagen (6,7) · H. Matsubara (8,9) · P. von Neumann-Cosel (1) · T. Papenbrock (6,7) · N. Pietralla (1) · V.Yu. Ponomarev (1) · A. Richter (1) · A. Schwenk (1,10,11) · A. Tamii (8) ((1) Institut fuer Kernphysik, Technische Universitaet Darmstadt, (2) TRIUMF, (3) Department of Physics and Astronomy, University of British Columbia, Vancouver, (4) Department of Physics and Astronomy, University of Manitoba, (5) Department of Physics and Astronomy, Texas AandM University-Commerce, (6) Physics Division, Oak Ridge National Laboratory, (7) Department of Physics and Astronomy, University of Tennessee, Knoxville, (8) Research Center for Nuclear Physics, Osaka University, (9) Tokyo Women's Medical University, (10) ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, (11) Max-Planck-Institut fuer Kernphysik)
The electric dipole strength distribution in Ca-48 between 5 and 25 MeV has been determined at RCNP, Osaka, from proton inelastic scattering experiments at forward angles. Combined with photoabsorption data at higher excitation energy, this enables for the first time the extraction of the electric dipole polarizability alpha_D(Ca-48) = 2.07(22) fm^3. Remarkably, the dipole response of Ca-48 is found to be very similar to that of Ca-40, consistent with a small neutron skin in Ca-48. The experimental results are in good agreement with ab initio calculations based on chiral effective field theory interactions and with state-of-the-art density-functional calculations, implying a neutron skin in Ca-48 of 0.14 - 0.20 fm.
↳ nucl-exnucl-thPRL(2017)·211 citations
13
Path-integral formula for local thermal equilibrium
Masaru Hongo🇯🇵
We develop a complete path-integral formulation of relativistic quantum fields in local thermal equilibrium, which brings about the emergence of thermally induced curved spacetime. The resulting action is shown to have full diffeomorphism invariance and gauge invariance in thermal spacetime with imaginary-time independent backgrounds. This leads to the notable symmetry properties of emergent thermal spacetime: Kaluza-Klein gauge symmetry, spatial diffeomorphism symmetry, and gauge symmetry. A thermodynamic potential in local thermal equilibrium, or the so-called Masseiu-Planck functional, is identified as a generating functional for conserved currents such as the energy-momentum tensor and the electric current.
↳ hep-thcond-mat.quant-gascond-mat.stat-mechhep-ph+1Annals Phys.(2017)·36 citations
14
Effect of medium recoil and $p_{T}$ broadening on single inclusive jet suppression in high-energy heavy-ion collisions
Xin-Nian Wang🇨🇳 · Shu-Yi Wei🇨🇳 · Han-Zhong Zhang🇨🇳
Jet energy loss and single inclusive jet suppression in high-energy heavy-ion collisions are studied within a pQCD parton model that includes both elastic and radiative interactions between jet shower and medium partons as they propagate through the quark-gluon plasma. The collisional energy loss of jets with a given cone-size is found to be relatively small comparing with the radiative energy loss. However the effect of transverse momentum broadening due to elastic scattering is significant in the calculation of radiative energy loss within the higher-twist formalism. The nuclear modification factors for single inclusive jets with different cone-sizes are calculated and compared to experimental data as measured by ALICE and ATLAS experiments in Pb+Pb collisions at $s_{NN} = 2.76$ TeV. Results on jet suppression in Pb+Pb collisions at $s_{NN} = 5.02$ TeV are also presented.
↳ hep-phnucl-thPRC(2017)·23 citations
15
The legacy of the experimental hadron physics programme at COSY
Colin Wilkin🇬🇧
The experimental hadronic physics programme at the COoler SYnchrotron of the Forschungszentrum Juelich terminated at the end of 2014. After describing the accelerator and the associated facilities, a review is presented of the major achievements in the field realized over the twenty years of intense research activity.
↳ nucl-exnucl-thEPJA(2017)·41 citations
16
QCD, with Strings Attached
Alberto Guijosa🇲🇽
In the nearly twenty years that have elapsed since its discovery, the gauge-gravity correspondence has become established as an efficient tool to explore the physics of a large class of strongly-coupled field theories. A brief overview is given here of its formulation and a few of its applications, emphasizing attempts to emulate aspects of the strong-coupling regime of quantum chromodynamics (QCD). To the extent possible, the presentation is self-contained, and in particular, it does not presuppose knowledge of string theory.
↳ hep-thgr-qchep-phnucl-thIJMPE(2016)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE