Nuclear Theory·nucl-th

Friday·February 5, 2016

14 papers—7 primary·7 cross-listed

01
[Submitted on 3 Feb 2016]
Valence-quark distribution functions in the kaon and pion
Chen Chen🇨🇳 · Lei Chang🇨🇳 · Craig D. Roberts🇺🇸 · Shaolong Wan🇨🇳 · Hong-Shi Zong🇨🇳
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed-quarks carry all a meson's momentum at a characteristic hadronic scale and vanishing as $(1 - x)^{2}$ when Bjorken- $x \to 1$ . Comparing such distributions within the pion and kaon, it is apparent that the size of SU(3)-flavour symmetry breaking in meson parton distribution functions is modulated by the flavour dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulae may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two-thirds of the pion's light-front momentum is carried by valence dressed-quarks at a characteristic hadronic scale, this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u-quark distributions that is in agreement with the single existing data set; and predict a u-quark distribution within the pion that agrees with a modern reappraisal of $π N$ Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
Comments:
10 pages, 3 figures. arXiv admin note: text overlap with arXiv:1406.5450
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1602.01502 [pdf]
PRD(2016)·124 citations
02
[Submitted on 4 Feb 2016]
Beam energy dependence of Hanbury-Brown-Twiss radii from a blast-wave model
S. Zhang🇨🇳 · Y. G. Ma🇨🇳 · J. H. Chen🇨🇳 · C. Zhong🇨🇳
The beam energy dependence of correlation lengths (the Hanbury-Brown-Twiss radii) is calculated by using a blast-wave model and the results are comparable with those from RHIC-STAR beam energy scan data as well as the LHC-ALICE measurements. A set of parameter for the blast-wave model as a function of beam energy under study are obtained by fit to the HBT radii at each energy point. The transverse momentum dependence of HBT radii is presented with the extracted parameters for Au + Au collision at $s_{N N} =$ 200 GeV and for Pb+Pb collisions at 2.76 TeV. From our study one can learn that particle emission duration can not be ignored while calculating the HBT radii with the same parameters. And tuning kinetic freeze-out temperature in a range will result in system lifetime changing in the reverse direction as it is found in RHIC-STAR experiment measurements.
Comments:
9 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1602.01564 [pdf]
Adv.High Energy Phys.(2016)·17 citations
03
[Submitted on 4 Feb 2016]
Isospin properties of quark matter from a 3-flavor NJL model
He Liu🇨🇳 · Jun Xu🇨🇳 · Lie-Wen Chen🇨🇳 · Kai-Jia Sun🇨🇳
We have studied the properties of hot and dense quark matter based on the 3-flavor Nambu-Jona-Lasinio (NJL) model as well as its Polyakov-loop extension (pNJL) with scalar-isovector and vector-isovector couplings. Provided a considerable large isospin asymmetry or isospin chemical potential, isospin splittings of constituent mass, chiral phase transition boundary, and critical point for $u$ and $d$ quarks can be observed for positive isovector coupling constants but are suppressed for negative ones. The quark matter symmetry energy decreases with the increasing isovector coupling constant, and is mostly enhanced in the pNJL model than in the NJL model. A positive scalar-isovector coupling constant is more likely to lead to an unstable isospin asymmetric quark matter. The isovector coupling has been further found to affect particle fractions as well as the equation of state in hybrid stars. Possible effects on the isospin properties of quark matter have also been discussed if the strangeness sector is further broken among the flavor symmetry.
Comments:
12 pages, 11 figures, significantly revised, version to appear in Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1602.01579 [pdf]
PRD(2016)·37 citations
04
[Submitted on 4 Feb 2016]
Low-energy hypernuclear spectra with microscopic particle-rotor model with relativistic point coupling hyperon-nucleon interaction
H. Mei🇯🇵 · K. Hagino🇯🇵 · J.M. Yao🇺🇸 · T. Motoba🇯🇵
We extend the microscopic particle-rotor model for hypernuclear low-lying states by including the derivative and tensor coupling terms in the point-coupling nucleon- $Λ$ particle ( $N Λ$ ) interaction. Taking $_{Λ}^{13}$ C as an example, we show that a good overall description for excitation spectra is achieved with four sets of effective $N Λ$ interaction. We find that the $Λ$ hyperon binding energy decreases monotonically with increasing the strengths of the high-order interaction terms. In particular, the tensor coupling term decreases the energy splitting between the first $1/ 2^{-}$ and $3/ 2^{-}$ states and increases the energy splitting between the first $3/ 2^{+}$ and $5/ 2^{+}$ states in $_{Λ}^{13}$ C.
Comments:
11 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1602.01588 [pdf]
PRC(2016)·16 citations
05
[Submitted on 4 Feb 2016]
New Astrophysical Reaction Rate for the $^{12} C (α, γ)^{16} O$ Reaction
Z. D. An · Y. G. Ma · G. T. Fan · Y. J. Li · Z. P. Chen · Y. Y. Sun
A new astrophysical reaction rate for $^{12}$ C( $α, γ$ ) $^{16}$ O has been evaluated on the basis of a global R-matrix fitting to the available experimental data. The reaction rates of $^{12}$ C( $α, γ$ ) $^{16}$ O for stellar temperatures between 0.04 $\leq$ $T_{9}$ $\leq$ 10 are provided in a tabular form and by an analytical fitting expression. At $T_{9}$ = 0.2, the reaction rate is (7.83 $\pm$ 0.35) $\times 1 0^{15}$ $c m^{3} mo l^{- 1} s^{- 1}$ , where stellar helium burning occurs.
Comments:
4 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1602.01692 [pdf]
ApJL(2016)·7 citations
06
[Submitted on 4 Feb 2016]
Kinematic constrains on interacting nucleons in $P b + P b$ collisions at $s_{N N} = 2.76$ TeV within the HIJING code
Khaled Abdel-Waged🇸🇦 · Nuha Felemban🇸🇦
The kinematic constrains on interacting nucleons in Large Hadron Collider (LHC) heavy-ion collisions are investigated in the framework of the Heavy Ion Jet Interaction Generator (HIJING) code incorporated with a collective cascade recipe. The latter is used to implement energy-momentum conservation constrains on both primary and secondary interacting nucleons. It is found that the energy-momentum conservation constrains on the interacting nucleons affect the whole charged particle pseudo-rapidity density distribution $(\frac{d N _{c h}}{d η})$ , at different centralities (from central (0-5\%) to peripheral (70-80\%) collisions), in Pb+Pb collisions at $s_{N N} = 2.76$ TeV. In particular, the kinematic constrains on interacting nucleons are shown to reduce $(\frac{d N _{c h}}{d η})$ yield at mid-pseudorapidity $(∣ η ∣ < 2)$ in all centrality intervals, which is consistent with the LHC data. In addition, the model predicts an enhancement of the hadron production at $∣ η ∣ > 8$ , which could be checked in future ALICE Zero Degree calorimeter. Such an enhancement is found to be mainly due to the interactions of protons at the spectator parts of the collision. This indicates that the kinematic constrains are important for a correct geometrical treatment of Pb+Pb collisions at LHC energies.
Comments:
9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1602.01701 [pdf]
PRC(2016)·4 citations
07
[Submitted on 4 Feb 2016]
A model for particle production in nuclear reactions at intermediate energies: application to C-C collisions at 95 MeV/nucleon
Jérémie Dudouet🇫🇷 · Dominique Durand🇫🇷
A model describing nuclear collisions at intermediate energies is presented and the results are compared with recently measured double differential cross sections in C-C reactions at 95 MeV/nucleon. Results show the key role played by geometrical effects and the memory of the entrance channel, in particular the momentum distributions of the two incoming nuclei. Special attention is paid to the description of processes occurring at mid-rapidity. To this end, a random particle production mechanism by means of a coalescence process in velocity space is considered in the overlap region of the two interacting nuclei.
Comments:
18 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1602.01734 [pdf]
PRC(2016)·8 citations
08
[Submitted on 2 Feb 2016] (cross-list from hep-ph)
Comment on "Breakdown of the expansion of finite-size corrections to the hydrogen Lamb shift in moments of charge distribution"
J. Arrington🇺🇸
In a recent paper, Hagelstein and Pascalutsa examine the error associated with an expansion of proton structure corrections to the Lamb shift in terms of moments of the charge distribution. They propose a small modification to a conventional parameterization of the proton's charge form factor and show that this can resolve the proton radius puzzle. However, while the size of the "bump" they add to the form factor is small, it is large compared to the total proton structure effects in the initial parameterization, yielding a final form factor that is unphysical. Reducing their modification to the point where the resulting form factor is physical does not allow for a resolution of the radius puzzle.
Comments:
Comment to appear (with Reply) in Physical Review A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1602.01461 [pdf]
PRA(2016)·3 citations
09
[Submitted on 3 Feb 2016] (cross-list from hep-ph)
Reactor antineutrino fluxes - status and challenges
Patrick Huber🇺🇸
In this contribution we describe the current understanding of reactor antineutrino fluxes and point out some recent developments. This is not intended to be a complete review of this vast topic but merely a selection of observations and remarks, which despite their incompleteness, will highlight the status and the challenges of this field.
Comments:
10 pages, 2 figures, 3 tables, prepared for the Nuclear Physics B special issue on Neutrino Oscillations celebrating the Nobel Prize in Physics 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Instrumentation and Detectors (physics.ins-det)
arXiv:
1602.01499 [pdf]
NPB(2016)·51 citations
10
[Submitted on 3 Feb 2016] (cross-list from astro-ph.HE)
Energetic emissions from deconfinement in compact stars and their relation to the critical end point in the QCD phase diagram
D. E. Alvarez-Castillo🇷🇺
In this work we study the case of deconfinement in compact star interiors in the presence of a strong first order phase transition associated to a critical end point in the QCD phase diagram. Neutron stars fulfilling these conditions show a third branch in the mass-radius diagram with the first and second branches being the white dwarfs and neutron stars configurations. The transition to the third branch can be reached by a pure hadronic neutron star through an induced collapse releasing energy that corresponds to a mass-energy difference between the second and third branch configurations. Physical outcomes of this phenomenon that can potentially explain the already detected astrophysical signals are discussed. In particular we present energy estimations for the case of a fast radio burst, seen as a double-peak structure in the object's light curve.
Comments:
7 pages, 3 figures, prepared for the Proceedings of the Conference "The International Workshop on Quark Phase Transition in Compact Objects and Multimessenger Astronomy: Neutrino Signals, Supernovae and Gamma-Ray Bursts", October 7-14,KChR, Nizhnij Arkhyz (SAO), KBR, Terskol (BNO), Russian Federation
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1602.01504 [pdf]
Publishing house Sneg, Pyatigorsk (2016) …·0 citations
11
[Submitted on 4 Feb 2016] (cross-list from hep-ph)
A Hydrodynamic Approach to the Study of Anisotropic Instabilities in Dissipative Relativistic Plasmas
Esteban Calzetta🇦🇷 · Alejandra Kandus🇧🇷
We develop a purely hydrodynamic formalism to describe collisional, anisotropic instabilities in a relativistic plasma, that are usually described with kinetic theory tools. Our main motivation is the fact that coarse-grained models of high particle number systems give more clear and comprehensive physical descriptions of those systems than purely kinetic approaches, and can be more easily tested experimentally as well as numerically. In particular, we aim at developing a theory that describes both a background non-equilibrium fluid configurations and its perturbations, to be able to account for the backreaction of the latter on the former. Our system of equations includes the usual conservation laws for the energy-momentum tensor and for the electric current, and the equations for two new tensors that encode the information about dissipation. To make contact with kinetic theory, we write the different tensors as the moments of a non-equilibrium one-particle distribution function (1pdf) which, for illustrative purposes, we take in the form of a Grad-like ansatz. Although this choice limits the applicability of the formalism to states not far from equilibrium, it retains the main features of the underlying kinetic theory. We assume the validity of the Vlasov-Boltzmann equation, with a collision integral given by the Anderson-Witting prescription, which is more suitable for highly relativistic systems than Marle's (or Bhatnagar, Gross and Krook) form, and derive the conservation laws by taking its corresponding moments. We apply our developments to study the emergence of instabilities in an anisotropic, but axially symmetric background. For small departures of isotropy we find the dispersion relation for normal modes, which admit unstable solutions for a wide range of values of the parameter space.
Comments:
13 pages. Three figures. The analysis of the instabilities was improved in order to compare our results with the ones in the literature. The motivation for developing a pure hydrodynamic formalism is clarified, the meaning of the different equations and tensors is explained. Typos and misplaced references were corrected. Uses revtex. Accepted for publication in Int. Jour. of Mod. Phys. A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
1602.01622 [pdf]
Int.J.Mod.Phys.A(2016)·8 citations
12
[Submitted on 4 Feb 2016] (cross-list from hep-ph)
Speed of Sound in Hadronic matter using Non-extensive Tsallis Statistics
Arvind Khuntia🇮🇳 · Pragati Sahoo🇮🇳 · Prakhar Garg🇮🇳 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦
The speed of sound ( $c_{s}$ ) is studied to understand the hydrodynamical evolution of the matter created in heavy-ion collisions. The quark-gluon plasma (QGP) formed in heavy-ion collisions evolves from an initial QGP to the hadronic phase via a possible mixed phase. Due to the system expansion in a first order phase transition scenario, the speed of sound reduces to zero as the specific heat diverges. We study the speed of sound for systems, which deviate from a thermalized Boltzmann distribution using non-extensive Tsallis statistics. In the present work, we calculate the speed of sound as a function of temperature for different $q$ -values for a hadron resonance gas. We observe a similar mass cut-off behaviour in non-extensive case for $c_{s}^{2}$ by including heavier particles, as is observed in the case of a hadron resonance gas following equilibrium statistics. Also, we explicitly present that the temperature where the mass cut-off starts, varies with the $q$ -parameter which hints at a relation between the degree of non-equilibrium and the limiting temperature of the system. It is shown that for values of $q$ above approximately 1.13 all criticality disappear in the speed of sound, i.e. the decrease in the value of the speed of sound, observed at lower values of $q$ , disappears completely.
Comments:
Same as published version in EPJA
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1602.01645 [pdf]
EPJA(2016)·28 citations
13
[Submitted on 4 Feb 2016] (cross-list from hep-ph)
Thermal Charm and Charmonium Production in Quark Gluon Plasma
Kai Zhou🇨🇳 · Zhengyu Chen🇨🇳 · Carsten Greiner🇩🇪 · Pengfei Zhuang🇨🇳
We study the effect of thermal charm production on charmonium regeneration in high energy nuclear collisions. By solving the kinetic equations for charm quark and charmonium distributions in Pb+Pb collisions, we calculate the global and differential nuclear modification factors $R_{AA} (N_{p a r t})$ and $R AA (p_{t})$ for $J /Ψ$ s. Due to the thermal charm production in hot medium, the charmonium production source changes from the initially created charm quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future Circular Collider (FCC), and the $J /Ψ$ suppression ( $R_{AA} < 1$ ) observed so far will be replaced by a strong enhancement ( $R_{AA} > 1$ ) at FCC at low transverse momentum.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1602.01667 [pdf]
PLB(2016)·33 citations
14
[Submitted on 4 Feb 2016] (cross-list from hep-ph)
Revealing transversity GPDs through the photoproduction of a photon and a $ρ$ meson
R. Boussarie🇫🇷 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷
Photoproduction of a pair of particles with large invariant mass is a natural extension of collinear QCD factorization theorems which have been much studied for deeply virtual Compton scattering and deeply virtual meson production. We discuss the production of a photon and a meson, where the wide angle Compton scattering on a meson subprocess factorizes from generalized parton distribution. We calculate at dominant twist and leading order in $α_{s}$ , the production cross-section of a transversely polarized $ρ$ meson which is sensitive to chiral-odd GPDs, and show that it may be measurable in near future JLab experiments.
Comments:
6 pages, 3 figures. Contribution to the proceedings of the 6th International Conference on Physics Opportunities at an Electron-Ion Collider (POETIC6), September 7-11, 2015, Palaiseau, France. The numerical plot (fig.3) has been corrected. arXiv admin note: text overlap with arXiv:1511.04371
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1602.01774 [pdf]
EPJ Web Conf.(2016)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE