Nuclear Theory·nucl-th

Friday·March 23, 2018

9 papers—2 primary·7 cross-listed

03
Short-lived modes from hydrodynamic dispersion relations
Benjamin Withers🇨🇭
We consider the dispersion relation of the shear-diffusion mode in relativistic hydrodynamics, which we generate to high order as a series in spatial momentum q for a holographic model. We demonstrate that the hydrodynamic series can be summed in a way that extends through branch cuts present in the complex q plane, resulting in the accurate description of multiple sheets. Each additional sheet corresponds to the dispersion relation of a different non-hydrodynamic mode. As an example we extract the frequencies of a pair of oscillatory non-hydrodynamic black hole quasinormal modes from the hydrodynamic series. The analytic structure of this model points to the possibility that the complete spectrum of gravitational quasinormal modes may be accessible from the hydrodynamic derivative expansion.
↳ hep-thgr-qcnucl-thJHEP(2018)·83 citations
04
Universal Formula for Baryon Spectra in Heavy-ion Collisions and its Implications
Rudolph C. Hwa🇺🇸 · Lilin Zhu🇨🇳
In an unconventional presentation of the data on the transverse momentum spectra of baryons produced in heavy-ion collisions, regularities are found that make possible the discovery of a universal formula valid for $p, Λ, Ξ$ and $Ω$ . The formula describes the baryon distributions over wide ranges of $p_{T} (0.5_{\sim}^{<} p_{T}_{\sim}^{<} 5$ GeV/c) for $0.06_{\sim}^{<} s_{N N}_{\sim}^{<} 3$ TeV, except for very peripheral collisions. Some aspects of their empirical properties are derived in the recombination model, resulting in a revelation of some features of the light and strange quark distributions before hadronization. Interpretation of the inverse slopes of their exponential behavior leads to an implication that cannot accommodate the conventional description of fluid flow. This is mainly a study of phenomenology without detailed model input.
↳ nucl-exhep-phnucl-thPRC(2018)·10 citations
05
Energy and Centrality Dependent Study of Deconfinement Phase Transition in a Color String Percolation Approach at RHIC Energies
Pragati Sahoo🇮🇳 · Sudipan De🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Raghunath Sahoo🇮🇳
We take the experimental data for transverse momentum spectra of identified charged hadrons in different centrality classes for nucleus-nucleus (A+A) collisions at various Relativistic Heavy-Ion Collider (RHIC) energies measured by the STAR collaboration. We analyse these data in the framework of color string percolation model (CSPM) in order to extract various percolation parameters at different centralities at RHIC energies to study the effect of collision geometry and collision energy. We use these parameters to study the centrality dependent behaviour of initial temperature of the percolation cluster, energy density, average transverse momentum, shear viscosity to entropy density ratio ( $η / s$ ) and trace anomaly for different energies at RHIC from $s_{NN}$ = 19.6 to 200 GeV. These observables are found to strongly depend on centrality at various collision energies. The critical percolation density, which is related to the deconfinement phase transition is achieved in the most central nucleus-nucleus collisions, while it fails in the peripheral collisions. A universal scaling is observed in color suppression factor and initial temperatures when studied as a function of charged particle pseudorapidity distribution scaled by nuclear overlap area at RHIC energies. The minimum of $η / s$ is observed in the most central collisions at $s_{NN}$ = 130 and 200 GeV.
↳ hep-phhep-exnucl-exnucl-thEPJA(2018)·39 citations
06
Derivation of spontaneously broken gauge symmetry from the consistency of effective field theory I: Massive vector bosons coupled to a scalar field
D. Djukanovic🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪
We revisit the problem of deriving local gauge invariance with spontaneous symmetry breaking in the context of an effective field theory. Previous derivations were based on the condition of tree-order unitarity. However, the modern point of view considers the Standard Model as the leading order approximation to an effective field theory. As tree-order unitarity is in any case violated by higher-order terms in an effective field theory, it is instructive to investigate a formalism which can be also applied to analyze higher-order interactions. In the current work we consider an effective field theory of massive vector bosons interacting with a massive scalar field. We impose the conditions of generating the right number of constraints for systems with spin-one particles and perturbative renormalizability as well as the separation of scales at one-loop order. We find that the above conditions impose severe restrictions on the coupling constants of the interaction terms. Except for the strengths of the self-interactions of the scalar field, that can not be determined at this order from the analysis of three- and four-point functions, we recover the gauge-invariant Lagrangian with spontaneous symmetry breaking taken in the unitary gauge as the leading order approximation to an effective field theory. We also outline the additional work that is required to finish this program.
↳ hep-thhep-lathep-phnucl-thPLB(2018)·4 citations
07
Spin polarized phases in strongly interacting matter: interplay between axial-vector and tensor mean fields
Tomoyuki Maruyama🇯🇵 · Eiji Nakano🇯🇵 · Kota Yanase🇯🇵 · Naotaka Yoshinaga🇯🇵
The spontaneous spin polarization of strongly interacting matter due to axial-vector and tensor type interactions is studied at zero temperature and high baryon-number densities. We start with the mean-field Lagrangian for the axial-vector and tensor interaction channels, and find in the chiral limit that the spin polarization due to the tensor mean field ( $U$ ) takes place first as the density increases for sufficiently strong coupling constants, and then that due to the axial-vector mean field ( $A$ ) emerges in the region of finite tensor mean field. This can be understood that making the axial-vector mean field finite requires a broken chiral symmetry somehow, which is achieved by the finite tensor mean field in the present case. It is also found from symmetry argument that there appear the type I (II) Nambu-Goldstone modes with a linear (quadratic) dispersion in the spin polarized phase with $U \neq = 0$ and $A = 0$ ( $U \neq = 0$ and $A \neq = 0$ ), although these two phases exhibit the same symmetry breaking pattern.
↳ hep-phnucl-thPRD(2018)·8 citations
08
Treatment of isomers in nucleosynthesis codes
René Reifarth · Stefan Fiebiger · Kathrin Göbel · Tanja Heftrich · Tanja Kausch · Christoph Köppchen · Deniz Kurtulgil · Christoph Langer · Benedikt Thomas · Mario Weigand
The decay properties of long-lived excited states (isomers) can have a significant impact on the destruction channels of isotopes under stellar conditions. In sufficiently hot environments, the population of isomers can be altered via thermal excitation or de-excitation. If the corresponding lifetimes are of the same order of magnitude as the typical time scales of the environment, the isomers have to be the treated explicitly. We present a general approach to the treatment of isomers in stellar nucleosynthesis codes and discuss a few illustrative examples. The corresponding code is available online at http://exp-astro.de/isomers/
↳ astro-ph.SRnucl-thInt.J.Mod.Phys.A(2018)·21 citations
09
Holographic Charged Fluid with Chiral Electric Separation Effect
Yanyan Bu🇨🇳 · Rong-Gen Cai🇨🇳 · Qing Yang🇨🇳 · Yun-Long Zhang🇰🇷
Hydrodynamics with both vector and axial currents is under study within a holographic model, consisting of canonical $U (1)_{V} \times U (1)_{A}$ gauge fields in an asymptotically AdS $_{5}$ black brane. When gravitational back-reaction is taken into account, the chiral electric separation effect (CESE), namely the generation of an axial current as the response to an external electric field, is realized naturally. Via fluid/gravity correspondence, all the first order transport coefficients in the hydrodynamic constitutive relations are evaluated analytically: they are functions of vector chemical potential $μ$ , axial chemical potential $μ_{5}$ and the fluid's temperature $T$ . Apart from the proportionality factor $μ μ_{5}$ , the CESE conductivity is found to be dependent on the dimensionless quantities $μ / T$ and $μ_{5} / T$ nontrivially. As a complementary study, frequency-dependent transport phenomena are revealed through linear response analysis, demonstrating perfect agreement with the results obtained from fluid/gravity correspondence.
↳ hep-thcond-mat.str-elgr-qcnucl-thJHEP(2018)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Short-lived modes from hydrodynamic dispersion relations

Universal Formula for Baryon Spectra in Heavy-ion Collisions and its Implications

Energy and Centrality Dependent Study of Deconfinement Phase Transition in a Color String Percolation Approach at RHIC Energies

Derivation of spontaneously broken gauge symmetry from the consistency of effective field theory I: Massive vector bosons coupled to a scalar field

Spin polarized phases in strongly interacting matter: interplay between axial-vector and tensor mean fields

Treatment of isomers in nucleosynthesis codes

Holographic Charged Fluid with Chiral Electric Separation Effect

Affiliations