Nuclear Theory·nucl-th

Tuesday·January 3, 2017

9 papers—2 primary·7 cross-listed

01
Forward-backward multiplicity correlations at the LHC from independent sources
Adam Olszewski🇵🇱 · Wojciech Broniowski🇵🇱
It is argued that the superposition approach, where partons are independently emitted from longitudinally extended sources in the early stage, is fully compatible with the experimental results for the forward-backward multiplicity correlations in Pb+Pb collisions at $s_{N N} = 2.76 TeV$ . The pertinent correlation analysis is based on the PhD Thesis of Ref. [1], which includes an unpublished analysis of data taken by the ALICE Collaboration. Our calculations show that in the experimentally covered pseudorapidity range $Δ η = 1.2$ , the initial sources in the backward and forward bins are maximally correlated, which complies to the string-like interpretation of the underlying early-stage production mechanism.
nucl-thnucl-exActa Phys.Polon.B(2017)·1 citation
02
Exit-Channel Suppression in Statistical Reaction Theory
G.F. Bertsch · T. Kawano
Statistical reaction theories such as Hauser-Feshbach assume that branching ratios follow Bohr's compound nucleus hypothesis by factorizing into independent probabilities for different channels. Corrections to the factorization hypothesis are known in both nuclear theory and quantum transport theory, particularly an enhanced memory of the entrance channel. We apply the Gaussian orthogonal ensemble to study a complementary suppression of exit channel branching ratios. The effect can be large enough to provide information on the number of exit channels. The effect is demonstrated for the branching ratios of neutron-induced reactions on a $^{235}$ U target.
nucl-thPRL(2017)·7 citations
03
The shear viscosity of two-flavor crystalline color superconducting quark matter
Sreemoyee Sarkar🇮🇳 · Rishi Sharma🇮🇳
We present the first calculation of the shear viscosity for two-flavor plane wave (FF) color superconducting quark matter. This is a member of the family of crystalline color superconducting phases of dense quark matter that may be present in the cores of neutron stars. The paired quarks in the FF phase feature gapless excitations on surfaces of crescent shaped blocking regions in momentum space and participate in transport. We calculate their contribution to the shear viscosity. We note that they also lead to dynamic screening of transverse $t^{1}$ , $t^{2}$ , $t^{3}$ gluons which are undamped in the 2SC phase. The exchange of these gluons is the most important mechanism of the scattering of the paired quarks. We find that the shear viscosity of the paired quarks is roughly a factor of $100$ smaller compared to the shear viscosity of unpaired quark matter. Our results may have implications for the damping of $r -$ modes in rapidly rotating, cold neutron stars.
↳ hep-phnucl-thPRD(2017)·15 citations
04
Efectos de Temperatura Finita y Curvatura en QCD y Modelos de Quarks Quirales
Eugenio Megias🇪🇸
We develop the heat kernel method in the context of finite temperature quantum field theory. We compute the heat kernel expansion in the presence of general gauge and scalar fields which may be non Abelian and non stationary. The Polyakov loop appears at finite temperature as a new gauge covariant operator. We apply this method in the computation of the fully gauge invariant effective action of QCD in the regime of high temperature. It is obtained the dimensionally reduced effective action of QCD as well. In the context of chiral quark models, in particular the Nambu--Jona-Lasinio and the spectral quark model, we apply this method to compute the low-energy chiral Lagrangian at finite temperature. The coupling of the Polyakov loop with these models allows to solve some inconsistencies appearing in the standard treatment at finite temperature: generation of multi-quark states, large $N_{c}$ counting, etc. On the other hand, we show that recent available lattice data for the renormalized Polyakov loop above the deconfinement phase transition exhibit unequivocal inverse power temperature corrections driven by a dimension 2 gluon condensate. This simple ansatz provides a good overall description of the data throughout the deconfinement phase until near the critical temperature with just two parameters. Finally, we study several chiral quark models in the light of chiral perturbation theory in curved space-time. The low energy structure of the energy momentum tensor in these models with SU(3) flavor symmetry is analyzed in the presence of external gravitational fields.
↳ hep-phhep-lathep-thnucl-thEditorial of the University of Granada. I…·0 citations
05
Anomalous transport and massive gravity theories
Eugenio Megias🇩🇪
We review the Kubo formulae relevant to study anomalous transport properties of relativistic fluids. We apply this formalism to perform a computation of the transport coefficients in a holographic massive gravity model including vorticity and external electromagnetic fields. We find an interesting phase in which the electric DC conductivity is negligible, while the anomalous conductivities turn out to be nonvanishing.
↳ hep-thcond-mat.str-elhep-phnucl-thJ.Phys.Conf.Ser.(2017)·4 citations
06
Anomaly induced transport in non-anomalous currents
Eugenio Megias🇩🇪
Quantum anomalies are one of the subtlest properties of relativistic field theories. They give rise to non-dissipative transport coefficients in the hydrodynamic expansion. In particular a magnetic field can induce an anomalous current via the chiral magnetic effect. In this work we explore the possibility that anomalies can induce a chiral magnetic effect in non-anomalous currents as well. This effect is implemented through an explicit breaking of the symmetries.
↳ hep-thcond-mat.str-elhep-phnucl-thEPJ Web Conf.(2017)·4 citations
07
Legendre Analysis of Differential Distributions in Hadronic Reactions
Yakov I. Azimov (PNPI)🇷🇺 · Igor I. Strakovsky (GWU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Ron L. Workman (GWU)🇺🇸
Modern experimental facilities, such as CBELSA, ELPH, JLab, MAMI and SPring-8 have provided a tremendous volume of data, often with wide energy and angular coverage, and with increasing precision. For reactions with two hadrons in the final state, these data are often presented as multiple sets of panels, with angular distributions at numerous specific energies. Such presentations have limited visual appeal, and their physical content is typically extracted through some model- dependent treatment. Instead, we explore the use of a Legendre series expansion with a relatively small number of essential coefficients. This approach has been applied in several recent experimental investigations. We present some general properties of the Legendre coefficients in the helicity framework and consider what physical information can be extracted without any model-dependent assumptions.
↳ hep-phhep-exnucl-exnucl-thPRC(2017)·4 citations
08
Volume Dependence of N-Body Bound States
Sebastian König🇩🇪 · Dean Lee🇺🇸
We derive the finite-volume correction to the binding energy of an N-particle quantum bound state in a cubic periodic volume. Our results are applicable to bound states with arbitrary composition and total angular momentum, and in any number of spatial dimensions. The only assumptions are that the interactions have finite range. The finite-volume correction is a sum of contributions from all possible breakup channels. In the case where the separation is into two bound clusters, our result gives the leading volume dependence up to exponentially small corrections. If the separation is into three or more clusters, there is a power-law factor that is beyond the scope of this work, however our result again determines the leading exponential dependence. We also present two independent methods that use finite-volume data to determine asymptotic normalization coefficients. The coefficients are useful to determine low-energy capture reactions into weakly bound states relevant for nuclear astrophysics. Using the techniques introduced here, one can even extract the infinite-volume energy limit using data from a single-volume calculation. The derived relations are tested using several exactly solvable systems and numerical examples. We anticipate immediate applications to lattice calculations of hadronic, nuclear, and cold atomic systems.
↳ hep-latcond-mat.quant-gasmath-phmath.MP+1PLB(2018)·70 citations
09
The Mar(e)k of QGP: Strangeness
Jan Rafelski🇺🇸
Strangeness signature of of quark-gluon plasma (QGP) is central to the exploration of baryon-dense matter: the search for the critical point and onset of deconfinement. I report on the discovery of QGP by means of strangeness: The key historical figures and their roles in this quest are introduced and the experimental results obtained are discussed. The important role of antihyperons is emphasized. The statistical hadronization model, and sudden hadronization are described. Results of present day data analysis: strangeness and entropy content of a large fireball, and the universal hadronization condition describing key features of all explored collision systems are presented.
↳ hep-phnucl-thphysics.hist-phActa Phys.Polon.Supp.B(2017)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE