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

Affiliations

first authorsco-authorsvia INSPIRE

Valence-quark distribution functions in the kaon and pion

Beam energy dependence of Hanbury-Brown-Twiss radii from a blast-wave model

Isospin properties of quark matter from a 3-flavor NJL model

Low-energy hypernuclear spectra with microscopic particle-rotor model with relativistic point coupling hyperon-nucleon interaction

New Astrophysical Reaction Rate for the 12C(α,γ)16O Reaction

Kinematic constrains on interacting nucleons in Pb+Pb collisions at sNN​​=2.76 TeV within the HIJING code

A model for particle production in nuclear reactions at intermediate energies: application to C-C collisions at 95 MeV/nucleon

Affiliations

New Astrophysical Reaction Rate for the $^{12} C (α, γ)^{16} O$ Reaction

Kinematic constrains on interacting nucleons in $P b + P b$ collisions at $s_{N N} = 2.76$ TeV within the HIJING code