Nuclear Theory·nucl-th

Tuesday·October 4, 2016

13 papers—10 primary·3 cross-listed

01
[Submitted on 1 Oct 2016]
On the sigma sigma term
Peter C. Bruns🇩🇪
We give some estimates for the light-quark mass dependence of the pole position of the sigma ( $f_{0} (500)$ ) resonance in the complex energy plane, with the help of a chiral Lagrangian for the resonance field and some input from hadronic models constrained by Chiral Perturbation Theory and elastic unitarity. We also speculate on the fate of the sigma resonance when the quark masses become unphysically large.
Comments:
Two minor typos corrected
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
arXiv:
1610.00119 [pdf]
5 citations
02
[Submitted on 1 Oct 2016]
Implications for (d,p) reaction theory from nonlocal dispersive optical model analysis of $^{40}$ Ca(d,p) $^{41}$ Ca
S. J. Waldecker · N. K. Timofeyuk
The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for the first time in the adiabatic analysis of a (d,p) reaction to generate distorted waves both in the entrance and exit channels. These potentials were designed and fitted by Mahzoon $e t a l .$ [Phys. Rev. Lett. 112, 162502 (2014)] to constrain relevant single-particle physics in a consistent way by imposing the fundamental properties, such as nonlocality, energy-dependence and dispersive relations, that follow from the complex nature of nuclei. However, the NLDOM prediction for the $^{40}$ Ca(d,p) $^{41}$ Ca cross sections at low energy, typical for some modern radioactive beam ISOL facilities, is about 70 $%$ higher than the experimental data despite being reduced by the NLDOM spectroscopic factor of 0.73. This overestimation comes most likely either from insufficient absorption or due to constructive interference between ingoing and outgoing waves. This indicates strongly that additional physics arising from many-body effects is missing in the widely used current versions of (d,p) reaction theories.
Comments:
14 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1610.00177 [pdf]
PRC(2016)·18 citations
03
[Submitted on 2 Oct 2016]
Strangeness at finite temperature from Lattice QCD
Jacquelyn Noronha-Hostler🇺🇸 · Rene Bellwied🇺🇸 · Jana Gunther🇩🇪 · Paolo Parotto🇺🇸 · Attila Pasztor🇩🇪 · Israel Portillo Vazquez🇺🇸 · Claudia Ratti🇺🇸
The precision reached by recent lattice QCD results allows for the first time to investigate whether the measured hadronic spectrum is missing some additional strange states, which are predicted by the Quark Model but have not yet been detected. This can be done by comparing some sensitive thermodynamic observables from lattice QCD to the predictions of the Hadron Resonance Gas model (with the inclusion of decays [3]). We propose a set of specific observables, defined as linear combinations of conserved charge fluctuations, which allow to investigate this issue for baryons containing one or more strange quarks separately. Applications of these observables to isolate the multiplicity fluctuations of kaons from lattice QCD, and their comparison with the experimental results, are also discussed.
Comments:
4 pages, 3 figures, contribution to the proceedings of the Strangeness in Quark Matter conference (June 27 to July 1, 2016, Berkeley, CA, USA)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.00221 [pdf]
J.Phys.Conf.Ser.(2017)·3 citations
04
[Submitted on 3 Oct 2016]
Excited State Mass spectra and Regge trajectories of Bottom Baryons
Kaushal Thakkar · Zalak Shah🇮🇳 · Ajay Kumar Rai🇮🇳 · P. C. Vinodkumar🇮🇳
We present the mass spectra of radial and orbital excited states of singly heavy bottom baryons; $Σ_{b}^{+}, Σ_{b}^{-}, Ξ_{b}^{-}, Ξ_{b}^{0}, Λ_{b}^{0}$ and $Ω_{b}^{-}$ . The QCD motivated hypercentral quark model is employed for the three body description of baryons and the form of confinement potential is hyper coulomb plus linear. The first order correction to the confinement potential is also incorporated in this work. The semi-electronic decay of $Ω_{b}$ and $Ξ_{b}$ are calculated using the spectroscopic parameters of the baryons. The computed results are compared with other theoretical predictions as well as with the available experimental observations. The Regge trajectories are plotted in (n, $M^{2}$ ) plane.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.00411 [pdf]
NPA(2017)·87 citations
05
[Submitted on 3 Oct 2016]
Signatures of shape phase transitions in odd-mass nuclei
K. Nomura · T. Nikšić · D. Vretenar
Quantum phase transitions between competing ground-state shapes of atomic nuclei with an odd number of protons or neutrons are investigated in a microscopic framework based on nuclear energy density functional theory and the particle-plus-boson-core coupling scheme. The boson-core Hamiltonian, as well as the single-particle energies and occupation probabilities of the unpaired nucleon, are completely determined by constrained self-consistent mean-field calculations for a specific choice of the energy density functional and paring interaction, and only the strength parameters of the particle-core coupling are adjusted to reproduce selected spectroscopic properties of the odd-mass system. We apply this method to odd-A Eu and Sm isotopes with neutron number $N \approx 90$ , and explore the influence of the single unpaired fermion on the occurrence of a shape phase transition. Collective wave functions of low-energy states are used to compute quantities that can be related to quantum order parameters: deformations, excitation energies, E2 transition rates and separation energies, and their evolution with the control parameter (neutron number) is analysed.
Comments:
15 pages, 13 figures; Accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1610.00469 [pdf]
PRC(2016)·37 citations
06
[Submitted on 3 Oct 2016]
Origins and Impacts of High-Density Symmetry Energy
Bao-An Li🇺🇸
What is nuclear symmetry energy? Why is it important? What do we know about it? Why is it so uncertain especially at high densities? Can the total symmetry energy or its kinetic part be negative? What are the effects of three-body and/or tensor force on symmetry energy? How can we probe the density dependence of nuclear symmetry energy with terrestrial nuclear experiments? What observables of heavy-ion reactions are sensitive to the high-density behavior of nuclear symmetry energy? How does the symmetry energy affect properties of neutron stars, gravitational waves and our understanding about the nature of strong-field gravity? In this lecture, we try to answer these questions as best as we can based on some of our recent work and/or understanding of research done by others. This note summarizes the main points of the lecture.
Comments:
Invited lecture given at the Carpathian Summer School of Physics 2016, Exotic Nuclei and Nuclear Astrophysics (VI), Sinaia, Romania, June 26 to July 9, 2016
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1610.00549 [pdf]
AIP Conf.Proc.(2017)·4 citations
07
[Submitted on 30 Sept 2016]
Positron production in collision of heavy nuclei
I.B. Khriplovich
We consider the electromagnetic production of positron in collision of slow heavy nuclei, with the simultaneously produced electron captured by one of the nuclei. The cross-section of the discussed process exceeds essentially the cross-section of $e^{+} e^{-}$ production.
Comments:
2 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.00586 [pdf]
Eur.Phys.J.Plus(2017)·3 citations
08
[Submitted on 29 Sept 2016]
Multi-strange hadrons and the precision extraction of QGP properties in the RHIC-BES domain
Jussi Auvinen🇺🇸 · Krzysztof Redlich🇵🇱 · Steffen A. Bass🇺🇸
We systematically compare an event-by-event transport+viscous hydrodynamics hybrid model to data from the RHIC beam energy scan using a general Bayesian method. We demonstrate how the inclusion of multistrange hadron observables affects the outcome of the Bayesian analysis and conduct an in depth analysis of the viability of $ϕ$ and $Ω$ as probes of the transition region between a deconfined quark-gluon plasma and hadronic phase in heavy ion collisions at higher-end RHIC collision energies. Utilizing UrQMD to model the final hadronic interactions, we examine the collision rates of $ϕ$ and $Ω$ and the modification to their transverse momentum spectra due to these interactions.
Comments:
7 pages, 4 figures. Talk given in "Strangeness in Quark Matter 2016", 27 June - 1 July 2016, UC Berkeley, CA, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.00589 [pdf]
J.Phys.Conf.Ser.(2017)·6 citations
09
[Submitted on 29 Sept 2016]
Systematic Extraction of QGP Properties
Jussi Auvinen🇺🇸 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸
We investigate the collision energy dependence of shear viscosity over the entropy density ratio $η / s$ in Au+Au collisions at $s_{N N} = 19.6, 39$ , and $62.4$ GeV, using Bayesian statistical analysis and Gaussian process emulators to explore the full input parameter space of a transport+hydrodynamics hybrid model. The ratio is found to decrease as a function of collision energy, supporting the results from previous studies performed with the same hybrid model.
Comments:
6 pages, 3 figures. Talk (given by S. A. Bass) at "Critical Point and Onset of Deconfinement (CPOD) 2016", Wroclaw, Poland, May 30th - June 4th, 2016
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1610.00590 [pdf]
Acta Phys.Polon.Supp.(2017)·4 citations
10
[Submitted on 3 Oct 2016]
A non-equilibrium microscopic description of spallation
P. Napolitani🇫🇷 · M. Colonna🇮🇹
We investigate the prompt emission of few intermediate-mass fragments in spallation reactions induced by protons and deuterons in the 1 GeV range. Such emission has a minor contribution to the total reaction cross section, but it may overcome evaporation and fission channels in the formation of light nuclides. The role of mean-field dynamics and phase-space fluctuations in these reactions is investigated through the Boltzmann-Langevin transport equation. We found that a process of frustrated fragmentation and re-aggregation is a prominent mechanism of production of IMFs which can not be assimilated to the statistical decay of a compound nucleus. Very interestingly, this process may yield a small number of IMF in the exit channel, which may even reduce to two, and be wrongly confused with ordinary asymmetric fission. This interpretation, inspired by nuclear-spallation experiments, can be generalised to heavy-ion collisions approaching the fragmentation threshold.
Comments:
Conf. proc. IWM-EC, 9-12 May 2016, Caen, France
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1610.00627 [pdf]
Nuovo Cim.C(2017)·3 citations
11
[Submitted on 2 Oct 2016] (cross-list from hep-lat)
SU(2N_F) symmetry of QCD at high temperature and its implications
L. Ya. Glozman🇦🇹
If above a critical temperature not only the SU(N_F)_L \times SU(N_F)_R chiral symmetry of QCD but also the U(1)_A symmetry is restored, then the actual symmetry of the QCD correlation functions and observables is SU(2N_F). Such a symmetry prohibits existence of deconfined quarks and gluons. Hence QCD at high temperature is also in the confining regime and elementary objects are SU(2N_F) symmetric "hadrons" with not yet known properties.
Comments:
3 pp, presented at "Critical Point and Onset of Deconfinement", Wroclaw, May, 30 - June,4, 2016
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1610.00275 [pdf]
Acta Phys.Polon.Supp.(2017)·21 citations
12
[Submitted on 3 Oct 2016] (cross-list from hep-ph)
Vector meson condensation in a pion superfluid
Tomas Brauner🇳🇴 · Xu-Guang Huang🇨🇳
We revisit the suggestion that charged rho-mesons undergo Bose-Einstein condensation in isospin-rich nuclear matter. Using a simple version of the Nambu-Jona-Lasinio (NJL) model, we conclude that rho-meson condensation is either avoided or postponed to isospin chemical potentials much higher than the rho-meson mass as a consequence of the repulsive interaction with the preformed pion condensate. In order to support our numerical results, we work out a linear sigma model for pions and rho-mesons, showing that the two models lead to similar patterns of medium dependence of meson masses. As a byproduct, we analyze in detail the mapping between the NJL model and the linear sigma model, focusing on conditions that must be satisfied for a quantitative agreement between the models.
Comments:
12 pages, 4 figures; v2: added references, matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1610.00426 [pdf]
PRD(2016)·26 citations
13
[Submitted on 3 Oct 2016] (cross-list from nucl-ex)
The first moment of azimuthal anisotropy in nuclear collisions from AGS to LHC energies
Subhash Singha🇺🇸 · Prashanth Shanmuganathan🇺🇸 · Declan Keane🇺🇸
We review topics related to the first moment of azimuthal anisotropy ( $v_{1}$ ), commonly known as directed flow, focusing on both charged particles and identified particles from heavy-ion collisions. Beam energies from the highest available, at the CERN LHC, down to projectile kinetic energies per nucleon of a few GeV per nucleon, as studied in experiments at the Brookhaven AGS, fall within our scope. We focus on experimental measurements and on theoretical work where direct comparisons with experiment have been emphasized. The physics addressed or potentially addressed by this review topic includes the study of Quark Gluon Plasma, and more generally, investigation of the Quantum Chromodynamics phase diagram and the equation of state describing the accessible phases.
Comments:
Accepted for publication in Advances in High Energy Physics
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1610.00646 [pdf]
Adv.High Energy Phys.(2016)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE