Nuclear Theory·nucl-th

Thursday·April 20, 2017

14 papers—9 primary·5 cross-listed

01
[Submitted on 18 Apr 2017]
Holographic Jet Shapes and their Evolution in Strongly Coupled Plasma
Jasmine Brewer🇺🇸 · Krishna Rajagopal🇺🇸 · Andrey Sadofyev🇺🇸 · Wilke van der Schee🇺🇸
Recently our group analyzed how the probability distribution for the jet opening angle is modified in an ensemble of jets that has propagated through an expanding cooling droplet of plasma [1]. Each jet in the ensemble is represented holographically by a string in the dual 4+1- dimensional gravitational theory with the distribution of initial energies and opening angles in the ensemble given by perturbative QCD. In [1], the full string dynamics were approximated by assuming that the string moves at the speed of light. We are now able to analyze the full string dynamics for a range of possible initial conditions, giving us access to the dynamics of holographic jets just after their creation. The nullification timescale and the features of the string when it has nullified are all results of the string evolution. This emboldens us to analyze the full jet shape modification, rather than just the opening angle modification of each jet in the ensemble as in [1]. We find the result that the jet shape scales with the opening angle at any particular energy. We construct an ensemble of dijets with energies and energy asymmetry distributions taken from events in proton-proton collisions, opening angle distribution as in [1], and jet shape taken from proton-proton collisions and scaled according to our result. We study how these observables are modified after we send the ensemble of dijets through the strongly-coupled plasma.
Comments:
4 pages, 4 figures. Talk presented at Quark Matter 2017, 5-11 February 2017, Chicago, IL, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1704.05455 [pdf]
NPA(2017)·10 citations
02
[Submitted on 18 Apr 2017]
Critical parameters of consistent relativistic mean-field models
O. Lourenço · M. Dutra · D. P. Menezes
In the present work, the critical temperature, critical pressure and critical density, known as the critical parameters related to the liquid-gas phase transition are calculated for 34 relativistic mean-field models, which were shown to satisfy nuclear matter constraints in a comprehensive study involving 263 models. The compressibility factor was calculated and all 34 models present values lower than the one obtained with the van der Waals equation of state. The critical temperatures were compared with experimental data and just two classes of models can reach values close to them. A correlation between the critical parameters and the incompressibility was obtained.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05498 [pdf]
PRC(2017)·25 citations
03
[Submitted on 18 Apr 2017]
Many-particle correlations and Coulomb effects on temperatures from fragment momentum fluctuations
S.R. Souza · M.B. Tsang · R. Donangelo
We investigate correlations in the fragment momentum distribution due to the propagation of fragments under the influence of their mutual Coulomb field, after the breakup of an excited nuclear source.The magnitude of the effects on the nuclear temperatures obtained from such distributions is estimated with the help of a simple approach in which a charged fragment interacts with a homogeneous charged sphere. The resuslts are used to correct the temperatures obtained from the asymptotic momentum distributions of fragments produced by a Monte-Carlo simulation in which the system's configuration at breakup is provided by the canonical version of the Statistical Multifragmentation Model. In a separate calculation, the dynamics of this many-particle charged system is followed in a molecular dynamics calculation until the fragments are far away from the breakup volume. The results suggest that, although the magnitude of the corrections is similar in both models, many-particle correlations present in the second approach are non-negligible and should be taken into account in order to minimize ambiguities in such studies.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05500 [pdf]
PRC(2017)·2 citations
04
[Submitted on 18 Apr 2017]
Deuteron Coulomb Excitation in Peripheral Collisions with a Heavy Ion
Weijie Du · Peng Yin · Guangyao Chen · Xingbo Zhao · James P. Vary
We develop and test an ab initio time-dependent Basis Function (tBF) method to solve non-perturbative and time-dependent problems in quantum mechanics. For our test problem, we apply this method to the Coulomb excitation of the deuteron by an impinging heavy ion. In the tBF method applied to deuterium, we employ wave functions for its bound and excited states to calculate its transition probabilities and the r.m.s. radius during the scattering process. For comparison, corresponding results based on first-order perturbation theory are also provided. For the Coulomb excitation process in a weak and time-varying Coulomb field, where higher-order effects are negligible, we obtain good agreement of the results based on these two methods. The tBF method is then applied to the Coulomb excitation process with stronger external field. The higher-order effects, such as those appearing in the reorientation of the polarization of the deuteron system, are analyzed.
Comments:
16 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05520 [pdf]
Proceedings of the International Conferen…·4 citations
05
[Submitted on 14 Apr 2017]
Quantifying the Chiral Magnetic Effect from Anomalous-Viscous Fluid Dynamics
Shuzhe Shi🇺🇸 · Yin Jiang🇩🇪 · Elias Lilleskov🇺🇸 · Yi Yin🇺🇸 · Jinfeng Liao🇺🇸
In this contribution we report a recently developed Anomalous-Viscous Fluid Dynamics (AVFD) framework, which simulates the evolution of fermion currents in QGP on top of the bulk expansion from data-validated VISHNU hydrodynamics. With reasonable estimates of initial conditions and magnetic field lifetime, the predicted CME signal is quantitatively consistent with change separation measurements in 200GeV Au-Au collisions at RHIC. We further develop the event-by-event AVFD simulations that allow direct evaluation of two-particle correlations arising from CME signal as well as the non-CME backgrounds. Finally we report predictions from AVFD simulations for the upcoming isobaric (Ru-Ru v.s. Zr-Zr ) collisions that could provide the critical test of the CME in heavy ion collisions.
Comments:
Contribution to the Proceedings of the XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017), Feb 5-11, Chicago, U.S.A. 4 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1704.05531 [pdf]
NPA(2017)·3 citations
06
[Submitted on 19 Apr 2017]
Bottomonium Continuous Production from Unequilibrium Bottom Quarks in Ultrarelativistic Heavy Ion Collisions
Baoyi Chen · Jiaxing Zhao🇨🇳
We employ the Langevin equation and Wigner function to describe the bottom equark dynamical evolutions and their formation into a bound state in the expanding Quark Gluon Plasma (QGP). The additional suppressions from parton inelastic scatterings are supplemented in the regenerated bottomonium. Hot medium modifications on $Υ (1 S)$ properties are studied consistently by taking the bottomonium potential to be the color-screened potential from Lattice results, which affects both $Υ (1 S)$ regeneration and dissociation rates. Finally, we calculated the $Υ (1 S)$ nuclear modification factor $R_{AA}^{rege}$ from bottom quark combination with different diffusion coefficients in Langevin equation, representing different thermalization of bottom quarks. In the central Pb-Pb collisions (b=0) at $s_{N N} = 5.02$ TeV, we find a non-negligible $Υ (1 S)$ regeneration, and it is small in the minimum bias centrality. The connections between bottomonium regeneration and bottom quark energy loss in the heavy ion collisions are also discussed.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05622 [pdf]
PLB(2017)·39 citations
07
[Submitted on 19 Apr 2017]
Analytical solutions for the radial Scarf II potential
G. Lévai · Á. Baran · P. Salamon · T. Vertse
The real Scarf II potential is discussed as a radial problem. This potential has been studied extensively as a one-dimensional problem, and now these results are used to construct its bound and resonance solutions for $l = 0$ by setting the origin at some arbitrary value of the coordinate. The solutions with appropriate boundary conditions are composed as the linear combination of the two independent solutions of the Schrödinger equation. The asymptotic expression of these solutions is used to construct the $S_{0} (k)$ s-wave $S$ -matrix, the poles of which supply the $k$ values corresponding to the bound, resonance and anti-bound solutions. The location of the discrete energy eigenvalues is analyzed, and the relation of the solutions of the radial and one-dimensional Scarf II potentials is discussed. It is shown that the generalized Woods--Saxon potential can be generated from the Rosen--Morse II potential in the same way as the radial Scarf II potential is obtained from its one-dimensional correspondent. Based on this analogy, possible applications are also pointed out.
Comments:
3 figs
Subjects:
Nuclear Theory (nucl-th); physics.class-ph (physics.class-ph)
arXiv:
1704.05634 [pdf]
PLA(2017)·5 citations
08
[Submitted on 19 Apr 2017]
Toroidal, compressive, and $E 1$ properties of low-energy dipole modes in $^{10}$ Be
Yoshiko Kanada-En'yo · Yuki Shikata
We studied dipole excitations in $^{10}$ Be based on an extended version of the antisymmetrized molecular dynamics, which can describe 1p-1h excitations and large amplitude cluster modes. Toroidal and compressive dipole operators are found to be good proves to separate the low-energy and high-energy parts of the isoscalar dipole excitations, respectively. Two low-energy $1^{-}$ states, the toroidal dominant $1_{1}^{-}$ state at $E \sim 8$ MeV and the $E 1$ dominant $1_{2}^{-}$ state at $E \sim 16$ MeV, were obtained. By analysis of transition current densities, the $1_{1}^{-}$ states is understood as a toroidal dipole mode with exotic toroidal neutron flow caused by rotation of a deformed $^{6} He$ cluster, whereas the $1_{2}^{-}$ state is regarded as a neutron-skin oscillation mode, which are characterized by surface neutron flow with inner isoscalar flow caused by the surface neutron oscillation against the $2 α$ core.
Comments:
15 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05649 [pdf]
PRC(2017)·23 citations
09
[Submitted on 19 Apr 2017]
Effect of initial-state nucleon shadowing on the elliptic flow of thermal photons
Pingal Dasgupta🇮🇳 · Rupa Chatterjee🇮🇳 · Sushant K. Singh🇮🇳 · Jan-e Alam🇮🇳
Recently the effect of nucleon shadowing on the Monte-Carlo Glauber initial condition was studied and its role on the centrality dependence of elliptic flow ( $v_{2}$ ) and fluctuations in initial eccentricity for different colliding nuclei were explored. It was found that the results with shadowing effects are closer to the QCD based dynamical model as well as to the experimental data. Inspired by this outcome, in this work we study the transverse momentum ( $p_{T}$ ) spectra and elliptic flow of thermal photons for Au+Au collisions at RHIC and Pb+Pb collisions at LHC by incorporating the shadowing effects in deducing the initial energy density profile required to solve the relativistic hydrodynamical equations. We find that the thermal photon spectra remain almost unaltered, however, the elliptic flow of photon is found to be enhanced significantly due to shadowing effects.
Comments:
9 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05715 [pdf]
PRC(2018)·12 citations
10
[Submitted on 5 Apr 2017] (cross-list from astro-ph.SR)
Reducing Uncertainties in the Production of the Gamma Emitting Nuclei 26Al, 44Ti, and 60Fe in Core Collapse Supernovae by Using Effective Helium Burning Rates
Sam Austin · Christopher West · Alexander Heger
We have used effective reaction rates (ERR) for the helium burning reactions to predict the yield of the gamma-emitting nuclei 26Al, 44Ti, and 60Fe in core col- lapse supernovae. The variations in the predicted yields for values of the reaction rates allowed by the ERR are much smaller than obtained previously, and smaller than other uncertainties. A "filter" for supernova nucleosynthesis yields based on pre-supernova structure was used to estimate the effect of failed supernovae on the initial mass function-averaged yields; this substantially reduced the yields of all these isotopes, but the predicted yield ratio 60Fe/26Al was little affected. The robustness of this ratio is promising for comparison with data, but it is larger than observed in nature; possible causes for this discrepancy are discussed.
Comments:
16 pages, 3 figures
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1704.01240 [pdf]
ApJL(2017)·9 citations
11
[Submitted on 18 Apr 2017] (cross-list from hep-ph)
The spin-dependent quark beam function at NNLO
Radja Boughezal🇺🇸 · Frank Petriello🇺🇸 · Ulrich Schubert🇺🇸 · Hongxi Xing🇺🇸
We calculate the beam function for longitudinally-polarized quarks through next-to-next-to-leading order (NNLO) in QCD perturbation theory. This is the last missing ingredient needed to apply the factorization theorem for the $N$ -jettiness event-shape variable in polarized collisions through the NNLO level. We present all technical details of our derivation. As a by-product of our calculation we provide the first independent check of the previously-obtained unpolarized quark beam function. We anticipate that our result will have phenomenological applications in describing data from polarized collisions.
Comments:
18 pages, 3 figures, references added, corrections made in some equations
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.05457 [pdf]
PRD(2017)·20 citations
12
[Submitted on 18 Apr 2017] (cross-list from hep-ph)
Dynamical vs. equilibrium properties of the QCD phase transition: a holographic perspective
Romulo Rougemont (IIP, Brazil)🇧🇷 · Renato Critelli (Sao Paulo U.)🇧🇷 · Jacquelyn Noronha-Hostler (Houston U.)🇺🇸 · Jorge Noronha (Sao Paulo U.)🇧🇷 · Claudia Ratti (Houston U.)🇺🇸
We employ an Einstein-Maxwell-Dilaton (EMD) holographic model, which is known to be in good agreement with lattice results for the QCD equation of state with $(2 + 1)$ flavors and physical quark masses, to investigate the temperature and baryon chemical potential dependence of the susceptibilities, conductivities, and diffusion coefficients associated with baryon, electric, and strangeness conserved charges. We also determine how the bulk and shear viscosities of the plasma vary in the plane of temperature and baryon chemical potential. The diffusion of conserved charges and the hydrodynamic viscosities in a baryon rich quark-gluon plasma are found to be suppressed with respect to the zero net baryon case. The transition temperatures associated with equilibrium and non-equilibrium quantities are determined as a function of the baryon chemical potential for the first time. Because of the crossover nature of the QCD phase transition even at moderately large values of the chemical potential, we find that the transition temperatures associated with different quantities are spread in the interval between $130 - 200$ MeV and they all decrease with increasing baryon chemical potential.
Comments:
20 pages, 19 figures, version accepted for publication in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1704.05558 [pdf]
PRD(2017)·118 citations
13
[Submitted on 19 Apr 2017] (cross-list from hep-ph)
Breit-Wigner distribution, quantum beats and GSI Anomaly
M. S. Hosseini🇮🇷 · S. A. Alavi🇮🇷
The relationship between Breit-Wigner distribution as an underlying basis for decaying unstable quantum systems and GSI experiment (anomaly) has not been addressed properly in the literatures. We show that quantum beats can be obtained using a superposition of two Breit-Wigner distributions. This modified distribution can explain the GSI time anomaly with quantum beats resulting from the existence of two energy levels of the decaying ion.
Comments:
7 pages, 2 Figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1704.05762 [pdf]
Annals Phys.(2019)·1 citation
14
[Submitted on 19 Apr 2017] (cross-list from hep-ph)
On the large-Q^2 behavior of the pion transition form factor
Gernot Eichmann🇵🇹 · Christian S. Fischer🇩🇪 · Esther Weil🇩🇪 · Richard Williams🇩🇪
We study the transition of non-perturbative to perturbative QCD in situations with possible violations of scaling limits. To this end we consider the singly- and doubly-virtual pion transition form factor $π^{0} \to γ γ$ at all momentum scales of symmetric and asymmetric photon momenta within the Dyson-Schwinger/Bethe-Salpeter approach. For the doubly virtual form factor we find good agreement with perturbative asymptotic scaling laws. For the singly-virtual form factor our results agree with the Belle data. At very large off-shell photon momenta we identify a mechanism that introduces quantitative modifications to Efremov-Radyushkin-Brodsky-Lepage scaling.
Comments:
5 pages, 7 figures, v3:contents revised, version published in PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1704.05774 [pdf]
PLB(2017)·49 citations

Affiliations

first authorsco-authorsvia INSPIRE