Nuclear Theory·nucl-th

Tuesday·May 19, 2015

10 papers—4 primary·6 cross-listed

01
Heavy flavor suppression predictions at 5.1 TeV Pb+Pb collisions at LHC
Magdalena Djordjevic🇷🇸 · Marko Djordjevic🇷🇸
High momentum hadron suppression is considered to be an excellent probe of jet-medium interactions in QCD matter created in ultra-relativistic heavy ion collisions. We previously showed that our dynamical energy loss formalism can accurately explain suppression measurements at 200 GeV Au+Au collisions at RHIC and 2.76 TeV Pb+Pb collisions at the LHC. With the upcoming LHC measurements at notably higher collision energies, there is a question of what differences, with respect to the current (2.76 TeV) measurements, can be expected. In this paper we concentrate on heavy flavor suppression at the upcoming 5.1 TeV Pb+Pb collisions energy at the LHC. Naively, one would expect a notably ( $\sim 30%$ ) larger suppression at 5.1 TeV collision energy, due to estimated (significant) energy loss increase when transitioning from 2.76 to 5.1 TeV. Surprisingly, more detailed calculations predict nearly the same suppression results at these two energies. We show that this unexpected result is due to an interplay of the following two effects, which essentially cancel each other: i) flattening of the initial distributions with increasing collision energies, and ii) significantly slower than naively expected increase in the energy loss. Therefore, the obtained nearly the same suppression provides a clear (qualitative and quantitative) test of our energy loss formalism.
nucl-thhep-phPRC(2015)·86 citations
02
Rapidity window dependences of higher order cumulants and diffusion master equation
Masakiyo Kitazawa🇯🇵
We study the rapidity window dependences of higher order cumulants of conserved charges observed in relativistic heavy ion collisions. The time evolution and the rapidity window dependence of the non-Gaussian fluctuations are described by the diffusion master equation. Analytic formulas for the time evolution of cumulants in a rapidity window are obtained for arbitrary initial conditions. We discuss that the rapidity window dependences of the non-Gaussian cumulants have characteristic structures reflecting the non-equilibrium property of fluctuations, which can be observed in relativistic heavy ion collisions with the present detectors. It is argued that various information on the thermal and transport properties of the hot medium can be revealed experimentally by the study of the rapidity window dependences, especially by the combined use, of the higher order cumulants. Formulas of higher order cumulants for a probability distribution composed of sub-probabilities, which are useful for various studies of non-Gaussian cumulants, are also presented.
nucl-thhep-phnucl-exNPA(2015)·24 citations
03
Origin of Low-Lying Enhanced E1 Strength in Rare-Earth Nuclei
M. Spieker · S. Pascu · A. Zilges · F. Iachello
The experimental $E 1$ strength distribution below 4 MeV in rare-earth nuclei suggests a local breaking of isospin symmetry. In addition to the octupole states, additional $1^{-}$ states with enhanced E1 strength have been observed in rare-earth nuclei by means of ( $γ, γ^{'}$ ) experiments. By reproducing the experimental results, the spdf interacting boson model calculations provide further evidence for the formation of an $α$ cluster in medium-mass nuclei and might provide a new understanding of the origin of low-lying E1 strength.
nucl-thPRL(2015)·49 citations
04
Neutron skin and halo in medium and heavy nuclei within the extended Thomas-Fermi theory
S.V. Lukyanov · A.I. Sanzhur
The neutron skin and halo distributions in medium and heavy nuclei are calculated within the extended Thomas-Fermi approximation. Calculations are carried out for the effective Skyrme-like forces using the direct variational method. The analytical expression for the isovector shift of the rms radii $Δ r_{n p}$ as a sum of skin- and halo-like terms is obtained. The contribution of halo and skin terms to $Δ r_{n p}$ are found to be approximately equal.
nucl-thNucl.Phys.Atom.Energy(2016)·4 citations
05
Flow harmonics $v_{n}$ at finite density
Yoshitaka Hatta🇯🇵 · Akihiko Monnai🇺🇸 · Bo-Wen Xiao🇨🇳
We generalize the Gubser solution of viscous hydrodynamics by including the finite density effect and analytically compute the flow harmonics $v_{n}$ . We explicitly show how $v_{n}$ and their viscous corrections depend on the chemical potential. The difference in $v_{n}$ between particles and antiparticles is also analytically computed and shown to be proportional to various chemical potentials and the viscosity. Excellent agreement is obtained between the results and the available experimental data from the SPS, RHIC and the LHC.
↳ hep-phnucl-exnucl-thPRD(2015)·31 citations
06
Implication of the observed $ψ (3770) \to p p ˉ π^{0}$ for studying the $p p ˉ \to ψ (3770) π^{0}$ process
Hao Xu🇨🇳 · Ju-Jun Xie🇨🇳 · Xiang Liu🇨🇳
We study the charmonium $p p ˉ \to ψ (3770) π^{0}$ reaction using the effective lagrangian approach where the contributions from well established $N^{*}$ states are considered, and all parameters are fixed in the process of $e^{+} e^{-} \to p p ˉ π^{0}$ at center of mass energy $s = 3.773$ GeV. The experimental data on the line shape of the mass distribution of the $e^{+} e^{-} \to p p ˉ π^{0}$ can be well reproduced. Based on the studying of $e^{+} e^{-} \to p p ˉ π^{0}$ , the total and differential cross sections of the $p p ˉ \to ψ (3770) π^{0}$ reaction are predicted. At the same time we evaluated also the cross sections of the $p p ˉ \to ψ (3686) π^{0}$ reaction. It is shown that the contribution of the nucleon pole to this reaction is largest from the reaction threshold within a wide range. However, the interference between nucleon pole and the other nucleon resonance can still change the angle distributions significantly. Those theoretical results may be test by the future experiments at $\mbox P$ ANDA.
↳ hep-phhep-exnucl-exnucl-thEPJC(2016)·14 citations
07
Entropy production in quantum Yang-Mills mechanics in semi-classical approximation
Hidekazu Tsukiji🇯🇵 · Hideaki Iida🇯🇵 · Teiji Kunihiro🇯🇵 · Akira Ohnishi🇯🇵 · Toru T. Takahashi🇯🇵
We discuss thermalization of isolated quantum systems by using the Husimi-Wehrl entropy evaluated in the semiclassical treatment. The Husimi-Wehrl entropy is the Wehrl entropy obtained by using the Husimi function for the phase space distribution. The time evolution of the Husimi function is given by smearing the Wigner function, whose time evolution is obtained in the semiclassical approximation. We show the efficiency and usefullness of this semiclassical treatment in describing entropy production of a couple of quantum mechanical systems, whose classical counter systems are known to be chaotic. We propose two methods to evaluate the time evolution of the Husimi-Wehrl entropy, the test-particle method and the two-step Monte-Carlo method. We demonstrate the characteristics of the two methods by numerical calculations, and show that the simultaneous application of the two methods ensures the reliability of the results of the Husimi-Wehrl entropy at a given time.
↳ hep-phhep-thnucl-thquant-phPTEP(2015)·5 citations
08
Interpretations of Elastic Electron Scattering
T.W. Donnelly🇺🇸 · D.K. Hasell🇺🇸 · R.G. Milner🇺🇸
Elastic scattering of relativistic electrons from the nucleon yields Lorentz invariant form factors that describe the fundamental distribution of charge and magnetism. The spatial dependence of the nucleon's charge and magnetism is typically interpreted in the Breit reference frame which is related by a Lorentz boost from the laboratory frame, where the nucleon is at rest. We construct a toy model to estimate how the charge and magnetic radii of the nucleon are modified between the Breit and lab. frames. This has implications for the ratio of the proton electric to magnetic elastic form factors as a function of momentum transfer as well as for determinations of the proton charge radius. Predicted corrections based on the model are provided for the rms charge radii of the deuteron, the triton, and the helium isotopes.
↳ nucl-exnucl-th3 citations
09
Monte-Carlo approach to particle-field interactions and the kinetics of the chiral phase transition
Carsten Greiner🇩🇪 · Christian Wesp🇩🇪 · Hendrik van Hees🇩🇪 · Alex Meistrenko🇩🇪
The kinetics of the chiral phase transition is studied within a linear quark-meson- $σ$ model, using a Monte-Carlo approach to semiclassical particle-field dynamics. The meson fields are described on the mean-field level and quarks and antiquarks as ensembles of test particles. Collisions between quarks and antiquarks as well as the $q q$ annihilation to $σ$ mesons and the decay of $σ$ mesons is treated, using the corresponding transition-matrix elements from the underlying quantum field theory, obeying strictly the rule of detailed balance and energy-momentum conservation. The approach allows to study fluctuations without making ad hoc assumptions concerning the statistical nature of the random process as necessary in Langevin-Fokker-Planck frameworks.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2015)·5 citations
10
Thermodynamics of an exactly solvable confining quark model
M. S. Guimaraes🇧🇷 · B. W. Mintz🇧🇷 · L. F. Palhares🇧🇷
The grand partition function of a model of confined quarks is exactly calculated at arbitrary temperatures and quark chemical potentials. The model is inspired by a softly BRST-broken version of QCD and possesses a quark mass function compatible with nonperturbative analyses of lattice simulations and Dyson-Schwinger equations. Even though the model is defined at tree level, we show that it produces a nontrivial and stable thermodynamic behaviour at any temperature or chemical potential. Results for the pressure, the entropy and the trace anomaly as a function of the temperature are qualitatively compatible with the effect of nonperturbative interactions as observed in lattice simulations. The finite density thermodynamics is also shown to contain nontrivial features, being far away from an ideal gas picture.
↳ hep-phhep-thnucl-thPRD(2015)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE