Nuclear Theory·nucl-th

Friday·July 13, 2018

14 papers—9 primary·5 cross-listed

01
[Submitted on 11 Jul 2018]
Anisotropic hydrodynamic modeling of 200 GeV Au-Au collisions
Dekrayat Almaalol🇺🇸 · Mubarak Alqahtani🇸🇦 · Michael Strickland🇺🇸
We compare phenomenological results from 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) with experimental data collected in RHIC 200 GeV Au-Au collisions. We present comparisons of identified particle spectra in different centrality clases, charged particle multiplicity versus pseudorapidity, identified particle multiplicity versus centrality across a wide range of particle species, identified particle elliptic flow versus transverse momentum, and charged particle elliptic flow as a function of transverse momentum and rapidity. We use the same aHydroQP and hadronic production/feed down codes that were used previously to describe LHC 2.76 TeV data. The aHydroQP hydrodynamic model includes the effects of both shear and bulk viscosities in addition to an infinite number of transport coefficients computed self-consistently in the relaxation time approximation. To convert to the final state hadrons, we use anisotropic Cooper-Frye freeze-out performed on a fixed-energy-density hypersurface and compute the production/feed down using a customized version of Therminator 2. We find good agreement with many heavy-ion collision observables using only smooth Glauber initial conditions parameterized by an initial central temperature of T_0 = 455 MeV, a constant shear viscosity to entropy density ratio eta/s= 0.179, and a switching (freeze-out) temperature of T_FO=130 MeV.
Comments:
23 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.04337 [pdf]
PRC(2019)·46 citations
02
[Submitted on 11 Jul 2018]
Models for nuclear reactions with weakly bound systems
Antonio M. Moro🇪🇸
In this contribution, I present a short overview of the theory of direct nuclear reactions, with special emphasis on the case of reactions induced by weakly-bound nuclei. After introducing some general results of quantum scattering theory, I present specific applications to elastic, inelastic, transfer and breakup reactions. For each of them, I first introduce the most standard framework, followed by some alternative models or extensions suitable for the case of weakly bound nuclei. A short discussion on semiclassical theory of Coulomb excitation and its application to breakup of halo nuclei is also provided.
Comments:
Proceedings of the International School of Physics Enrico Fermi: "Nuclear Physics with Stable and Radioactive Ion Beams". Several typos fixed in this version
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1807.04349 [pdf]
Proc.Int.Sch.Phys.Fermi(2019)·9 citations
03
[Submitted on 12 Jul 2018]
Perturbative $N N$ scattering in chiral effective field theory
Shaowei Wu🇨🇳 · Bingwei Long🇨🇳
Within the framework of chiral effective field theory, perturbative calculation for $N N$ scattering is carried out in partial waves with orbital angular momentum $L ⩾ 1$ . The primary goal is to identify the lowest angular momenta at which perturbative treatment of chiral forces can apply. Results up to the order where the subleading two-pion exchange appears are shown. It is concluded that perturbation theory applies to all partial waves but $^{1} S_{0}$ , $^{3} S_{1} -^{3} D_{1}$ , and $^{3} P_{0}$ . Where it is applicable, perturbation theory with the delta-less chiral forces produces good agreement with the empirical phase shifts up to $k_{c.m.} ≃ 300$ MeV.
Comments:
Matches published version; suppression of TPEs accounted for at referee's suggestion; main conclusion unchanged, that most P waves and higher waves are perturbative
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04407 [pdf]
PRC(2019)·42 citations
04
[Submitted on 12 Jul 2018]
Neutron stars and stellar mergers as a laboratory for dense QCD matter
Aleksi Vuorinen🇫🇮
Neutron star observations, including direct mass and radius measurements as well as the analysis of gravitational wave signals emitted by stellar mergers, provide valuable and unique insights into the properties of strongly interacting matter at high densities. In this proceedings contribution, I review recent efforts to systematically constrain the equation of state (EoS) of dense nuclear and quark matter using a combination of ab initio particle and nuclear physics calculations and astrophysical data. In particular, I discuss the constraints that the gravitational wave observation GW170817 has placed on the EoS, and comment on the future prospects of improving the accuracy, to which this quantity is known.
Comments:
7 pages, 2 figures. Invited plenary talk at the 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Venice, Italy, 13-19 May 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.04480 [pdf]
NPA(2019)·16 citations
05
[Submitted on 12 Jul 2018]
Eta and Etaprime Photoproduction on the Nucleon with the Isobar Model EtaMAID2018
L. Tiator🇩🇪 · M. Gorchtein🇩🇪 · V. L. Kashevarov🇩🇪 · K. Nikonov🇩🇪 · M. Ostrick🇩🇪 · M. Hadzimehmedovic🇧🇦 · R. Omerovic🇧🇦 · H. Osmanovic🇧🇦 · J. Stahov🇧🇦 · A. Svarc🇭🇷
The isobar model EtaMAID has been updated with new and high precision data for eta and etaprime photoproduction on protons and neutrons from MAMI, ELSA, GRAAL and CLAS. The background is described in a recently developed Regge-cut model, and for the resonance part the whole list of nucleon resonances has been investigated with 21 N* states contributing to eta photoproduction and 12 N* states contributing to etaprime photoproduction. A new approach is discussed to avoid double counting in the overlap region of Regge and resonances. A comparison is done among four newly updated partial waves analyses for observables and partial waves. Finally, the possibility of a narrow resonance near W=1900 MeV is discussed, that would be able to explain unexpected energy and angular dependence of observables in p(gamma,etaprime)p near etaprime threshold.
Comments:
31 pages, 29 figures, replaced with revised version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.04525 [pdf]
EPJA(2018)·67 citations
06
[Submitted on 12 Jul 2018]
The nuclear configurational entropy approach to dynamical QCD effects
Gayane Karapetyan🇧🇷
This paper scrutinizes the dynamical QCD effects influence on mesons, namely, the mean-square root radius of a pion in the holographic light-front wave function setup, in the context of the AdS/QCD. The nuclear configurational entropy, associated to mesonic holographic light-front wave functions, is shown to have a critical point that optimizes the two parameters of the spin-improved light-front wave function. The mean-square root pion radius and its cross-section, computed upon these derived values, match the exact existing experimental data to the precision of 0.14\%, below the experimental error at the PDG.
Comments:
5 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.04540 [pdf]
PLB(2018)·50 citations
07
[Submitted on 12 Jul 2018]
Quantum entanglement in the initial and final state of relativistic heavy ion collisions
Rene Bellwied🇺🇸
The possibility of quantum entanglement leading to a seemingly thermal distribution of the initial partonic state that maps to the final hadronic state in the evolution of the deconfined phase generated in relativistic heavy ion collisions is discussed in the context of early thermalization and final state particle distributions obtained in experiments at RHIC and the LHC.
Comments:
6 pages, no figures, proceedings to the 34th Winter Workshop on Nuclear Dynamics (WWND 2018)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.04589 [pdf]
J.Phys.Conf.Ser.(2018)·16 citations
08
[Submitted on 12 Jul 2018]
A Quasiparticle Transport Explanation for Collectivity in the Smallest of Collision Systems (p + p and e+e-)
J.L. Nagle🇺🇸 · J. Orjuela Koop🇺🇸
The field of heavy ion physics is at a crossroads in understanding experimental signatures of collectivity in small collision systems, p + p and p(d/3He) + A, at RHIC and the LHC. A wealth of data obtained in the latter class of asymmetric systems indicate the existence of particle emission patterns similar to those observed in larger A+A collisions [1], raising the question of whether the same physics is at play in both cases, lest the cruelty of nature be somehow exposed. In this talk, we present an extension of earlier studies using the quasiparticle transport model AMPT to predict particle emission patterns in the smallest of collision systems, namely p + p and e+e-. The e+e- results have been previously published [2] and we thus focus here on an extended set of calculations, as shown at the Quark Matter 2018 Conference.
Comments:
4 pages, 4 figures, International Quark Matter 2018 Proceedings
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04619 [pdf]
NPA(2019)·9 citations
09
[Submitted on 12 Jul 2018]
Hybrid model with dynamical sources for heavy-ion collisions at BES energies
Lipei Du🇺🇸 · Ulrich Heinz🇺🇸 · Gojko Vujanovic🇺🇸
We develop a (3+1)-dimensional hybrid evolution model for heavy-ion collisions with dynamical sources for the energy-momentum tensor and baryon current. During an initial pre-equilibrium stage based on UrQMD, the four-momenta and baryon numbers carried by secondary particles created within UrQMD are fed continuously, after a short thermalization time, into a (3+1)-dimensional viscous hydrodynamic evolution module including baryon transport. The sensitivity of the initial conditions to model parameters and the effect of baryon diffusion on the hydrodynamic evolution are studied.
Comments:
4 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.04721 [pdf]
NPA(2019)·52 citations
10
[Submitted on 11 Jul 2018] (cross-list from hep-ph)
$η^{'} \to η π π$ decays in unitarized resonance chiral theory
Sergi Gonzàlez-Solís🇨🇳 · Emilie Passemar🇺🇸
We study the hadronic $η^{'} \to η π π$ decays within the framework of $U (3)_{L} \otimes U (3)_{R}$ Chiral Perturbation Theory including resonance states and the complete one-loop corrections. The amplitude is projected in partial waves and unitarized by means of the $N / D$ method resumming both the important $S$ -and $D$ -wave $π π$ and the subleading $S$ -wave $π η$ final-state interactions. The participating scalar multiplet mass and coupling strengths are determined from fits to the Dalitz plot experimental data recently released by the A2 collaboration. As a byproduct of our analysis, the associated Dalitz-plot slope parameters are found to be $a = - 0.072 (7)_{stat} (8)_{syst}, b = - 0.052 (1)_{stat} (2)_{syst}, d = - 0.051 (8)_{stat} (6)_{syst}$ , which lie in the ballpark of the current experimental and theoretical determinations.
Comments:
45 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1807.04313 [pdf]
EPJC(2018)·26 citations
11
[Submitted on 12 Jul 2018] (cross-list from cond-mat.quant-gas)
Finite-temperature equation of state of polarized fermions at unitarity
Lukas Rammelmüller🇩🇪 · Andrew C. Loheac🇺🇸 · Joaquín E. Drut🇺🇸 · Jens Braun🇩🇪
We study in a nonperturbative fashion the thermodynamics of a unitary Fermi gas over a wide range of temperatures and spin polarizations. To this end, we use the complex Langevin method, a first principles approach for strongly coupled systems. Specifically, we show results for the density equation of state, the magnetization, and the magnetic susceptibility. At zero polarization, our results agree well with state-of-the art results for the density equation of state and with experimental data. At finite polarization and low fugacity, our results are in excellent agreement with the third-order virial expansion. In the fully quantum mechanical regime close to the balanced limit, the critical temperature for superfluidity appears to depend only weakly on the spin polarization.
Comments:
10 pages, 9 figures, including supplemental material, published version
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1807.04664 [pdf]
PRL(2018)·38 citations
12
[Submitted on 12 Jul 2018] (cross-list from hep-th)
Bulk Viscosity at Extreme Limits: From Kinetic Theory to Strings
Alina Czajka🇨🇦 · Keshav Dasgupta🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Aalok Misra🇮🇳 · Michael Richard🇨🇦 · Karunava Sil🇮🇳
In this paper we study bulk viscosity in a thermal QCD model with large number of colors at two extreme limits: the very weak and the very strong 't Hooft couplings. The weak coupling scenario is based on kinetic theory, and one may go to the very strong coupling dynamics via an intermediate coupling regime. Although the former has a clear description in terms of kinetic theory, the intermediate coupling regime, which uses lattice results, suffers from usual technical challenges that render an explicit determination of bulk viscosity somewhat difficult. On the other hand, the very strong 't Hooft coupling dynamics may be studied using string theories at both weak and strong string couplings using gravity duals in type IIB as well as M-theory respectively. In type IIB we provide the precise fluctuation modes of the metric in the gravity dual responsible for bulk viscosity, compute the speed of sound in the medium and analyze the ratio of the bulk to shear viscosities. In M-theory, where we uplift the type IIA mirror dual of the UV complete type IIB model, we study and compare both the bulk viscosity and the sound speed by analyzing the quasi-normal modes in the system at strong IIA string coupling. By deriving the spectral function, we show the consistency of our results both for the actual values of the parameters involved as well for the bound on the ratio of bulk to shear viscosities.
Comments:
143 pages, 20 figures, LaTeX; v2: Typos corrected and references added; v3: Text elaborated at many places, sub-section 2.7 and appendix D added, figures 7 and 16 modified; typos corrected and references added. Final version to appear in JHEP
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1807.04713 [pdf]
JHEP(2019)·45 citations
13
[Submitted on 12 Jul 2018] (cross-list from gr-qc)
Constraints on the moment of inertia of PSR J0737-3039A from GW170817
Philippe Landry🇺🇸 · Bharat Kumar🇮🇳
Continued observation of PSR J0737-3039, the double pulsar, is expected to yield a precise determination of its primary component's moment of inertia in the next few years. Since the moment of inertia depends sensitively on the neutron star's internal structure, such a measurement will constrain the equation of state of ultra-dense matter, which is believed to be universal. Independent equation-of-state constraints have already been established by the gravitational-wave measurement of the neutron-star tidal deformability in GW170817. Here, using well-known universal relations among neutron star observables, we translate the reported 90%-credible bounds on tidal deformability into a direct constraint, $I_{⋆} = 1.1 5_{- 0.24}^{+ 0.38} \times 1 0^{45} g cm^{2}$ , on the moment of inertia of PSR J0737-3039A. Should a future astrophysical measurement of $I_{⋆}$ disagree with this prediction, it could indicate a breakdown in the universality of the neutron-star equation of state.
Comments:
8 pages, 4 figures; matches the published version
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1807.04727 [pdf]
ApJL(2018)·92 citations
14
[Submitted on 12 Jul 2018] (cross-list from hep-lat)
Finite-volume spectrum of $π^{+} π^{+}$ and $π^{+} π^{+} π^{+}$ systems
Maxim Mai🇺🇸 · Michael Doring🇺🇸
The ab-initio understanding of hadronic three-body systems above threshold, such as exotic resonances or the baryon spectrum, requires the mapping of the finite-volume eigenvalue spectrum, produced in lattice QCD calculations, to the infinite volume. We present the first application of such a formalism to a physical system in form of three interacting positively charged pions. The results for the ground state energies agree with the available lattice QCD results by the NPLQCD collaboration at unphysical pion masses. Extrapolations to physical pion masses are performed using input from effective field theory. The excited energy spectrum is predicted. This demonstrates the feasibility to determine three-body amplitudes above threshold from lattice QCD, including resonance properties of axial mesons, exotics, and excited baryons.
Comments:
version accepted for publ. in Phys. Rev. Lett
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.04746 [pdf]
PRL(2019)·156 citations

Affiliations

first authorsco-authorsvia INSPIRE