Nuclear Theory·nucl-th

Tuesday·July 21, 2015

12 papers—4 primary·8 cross-listed

01
[Submitted on 20 Jul 2015]
Constraining the symmetry energy content of nuclear matter from nuclear masses: a covariance analysis
C. Mondal · B. K. Agrawal · J. N. De
Elements of nuclear symmetry energy evaluated from different energy density functionals parametrized by fitting selective bulk properties of few representative nuclei are seen to vary widely. Those obtained from experimental data on nuclear masses across the periodic table, however, show that they are better constrained. A possible direction in reconciling this paradox may be gleaned from comparison of results obtained from use of the binding energies in the fitting protocol within a microscopic model with two sets of nuclei, one a representative standard set and another where very highly asymmetric nuclei are additionally included. A covariance analysis reveals that the additional fitting protocol reduces the uncertainties in the nuclear symmetry energy coefficient, its slope parameter as well as the neutron-skin thickness in $^{208}$ Pb nucleus by $\sim 50%$ . The central values of these entities are also seen to be slightly reduced.
Comments:
6 pages, 2 figures, Accepted in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1507.05384 [pdf]
PRC(2015)·38 citations
02
[Submitted on 20 Jul 2015]
Anti-shadowing Effect on Charmonium Production at a Fixed-target Experiment Using LHC Beams
Kai Zhou🇨🇳 · Zhengyu Chen🇨🇳 · Pengfei Zhuang🇨🇳
We investigate charmonium production in Pb+Pb collisions at LHC beam energy $E_{lab}$ =2.76 A TeV at fixed-target experiment ( $s_{NN}$ =72 GeV). In the frame of a transport approach including cold and hot nuclear matter effects on charmonium evolution, we focus on the anti-shadowing effect on the nuclear modification factors $R_{AA}$ and $r_{AA}$ for the $J / ψ$ yield and transverse momentum. The yield is more suppressed at less forward rapidity ( $y_{lab} ≃$ 2) than that at very forward rapidity ( $y_{lab} ≃$ 4) due to the shadowing and anti-shadowing in different rapidity bins.
Comments:
7 pages, 3 figures; submitted to Advances in High Energy Physics. arXiv admin note: text overlap with arXiv:1409.5559
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1507.05413 [pdf]
Adv.High Energy Phys.(2015)·3 citations
03
[Submitted on 20 Jul 2015]
Quantum Monte Carlo calculations of neutron matter with chiral three-body forces
I. Tews🇩🇪 · S. Gandolfi🇺🇸 · A. Gezerlis🇨🇦 · A. Schwenk🇩🇪
Chiral effective field theory (EFT) enables a systematic description of low-energy hadronic interactions with controlled theoretical uncertainties. For strongly interacting systems, quantum Monte Carlo (QMC) methods provide some of the most accurate solutions, but they require as input local potentials. We have recently constructed local chiral nucleon-nucleon (NN) interactions up to next-to-next-to-leading order (N $^{2}$ LO). Chiral EFT naturally predicts consistent many-body forces. In this paper, we consider the leading chiral three-nucleon (3N) interactions in local form. These are included in auxiliary field diffusion Monte Carlo (AFDMC) simulations. We present results for the equation of state of neutron matter and for the energies and radii of neutron drops. In particular, we study the regulator dependence at the Hartree-Fock level and in AFDMC and find that present local regulators lead to less repulsion from 3N forces compared to the usual nonlocal regulators.
Comments:
10 pages, 8 figures, 1 table, published version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1507.05561 [pdf]
PRC(2016)·185 citations
04
[Submitted on 20 Jul 2015]
Fluid dynamic propagation of initial baryon number perturbations on a Bjorken flow background
Stefan Floerchinger🇨🇭 · Mauricio Martinez🇺🇸
Baryon number density perturbations offer a possible route to experimentally measure baryon number susceptibilities and heat conductivity of the quark gluon plasma. We study the fluid dynamical evolution of local and event-by-event fluctuations of baryon number density, flow velocity and energy density on top of a (generalized) Bjorken expansion. To that end we use a background-fluctuation splitting and a Bessel-Fourier decomposition for the fluctuating part of the fluid dynamical fields with respect to the azimuthal angle, the radius in the transverse plane and rapidity. We examine how the time evolution of linear perturbations depends on the equation of state as well as on shear viscosity, bulk viscosity and heat conductivity for modes with different azimuthal, radial and rapidity wave numbers. Finally we discuss how this information is accessible to experiments in terms of the transverse and rapidity dependence of correlation functions for baryonic particles in high energy nuclear collisions.
Comments:
36 pages, 11 figures; v3: change in the format of the latex file. Minor changes in the text. Typos corrected and updated references. Tweak in Fig. 1-11. Accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1507.05569 [pdf]
PRC(2015)·37 citations
05
[Submitted on 17 Jul 2015] (cross-list from hep-ph)
How to reveal the exotic nature of the P_c(4450)
Feng-Kun Guo🇩🇪 · Ulf-G. Meißner🇩🇪 · Wei Wang🇨🇳 · Zhi Yang🇩🇪
The LHCb Collaboration announced two pentaquark-like structures in the $J / ψ p$ invariant mass distribution. We show that the current information on the narrow structure at 4.45 GeV is compatible with kinematical effects of the rescattering from $χ_{c 1} p$ to $J / ψ p$ : First, it is located exactly at the $χ_{c 1} p$ threshold. Second, the mass of the four-star well-established $Λ (1890)$ is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the $χ_{c 1} p$ threshold, and third, there is a narrow structure at the $χ_{c 1} p$ threshold but not at the $χ_{c 0} p$ and $χ_{c 2} p$ thresholds. In order to check whether that structure corresponds to a real exotic resonance, one has to measure the process $Λ_{b}^{0} \to K^{-} χ_{c 1} p$ . If the $P_{c} (4450)$ structure exists in the $χ_{c 1} p$ invariant mass distribution as well, then the structure cannot be just a kinematical effect but is a real resonance, otherwise, one cannot conclude the $P_{c} (4450)$ to be another exotic hadron. In addition, it is also worthwhile to measure the decay $Υ (1 S) \to J / ψ p p ˉ$ : a narrow structure at 4.45 GeV but not at the $χ_{c 0} p$ and $χ_{c 2} p$ thresholds would exclude the possibility of a pure kinematical effect.
Comments:
9 pages, 4 figures. Version published in PRD as a Rapid Communication
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1507.04950 [pdf]
PRD(2015)·357 citations
06
[Submitted on 17 Jul 2015] (cross-list from cond-mat.mes-hall)
Magnetotransport in Dirac metals: chiral magnetic effect and quantum oscillations
Gustavo M. Monteiro🇺🇸 · Alexander G. Abanov🇺🇸 · Dmitri E. Kharzeev🇺🇸
Dirac metals are characterized by the linear dispersion of fermionic quasi-particles, with the Dirac point hidden inside a Fermi surface. We study the magnetotransport in these materials using chiral kinetic theory to describe within the same framework both the negative magnetoresistance caused by chiral magnetic effect and quantum oscillations in the magnetoresistance due to the existence of the Fermi surface. We discuss the relevance of obtained results to recent measurements on $C d_{3} A s_{2}$ .
Comments:
10 pages, 2 figures
Subjects:
Mesoscale and Nanoscale Physics (cond-mat.mes-hall); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.05077 [pdf]
PRB(2015)·11 citations
07
[Submitted on 18 Jul 2015] (cross-list from hep-ph)
The Proton Mass and Scale-Invariant Hidden Local Symmetry for Compressed Baryonic Matter
Mannque Rho🇫🇷
I discuss how to access dense baryonic matter of compact stars by combining hidden local symmetry (HLS) of light-quark vector mesons with spontaneously broken scale invariance of a (pseudo) Nambu-Goldstone boson, dilaton, in a description that parallels the approach to dilatonic Higgs. Some of the surprising observations are that the bulk of proton mass is not Nambu-Goldstonian, parity doubling emerges at high density and the EoS of baryonic matter can be soft enough for heavy-ion processes at low density and stiff enough at high density for $\sim 2$ solar mass neutron stars.
Comments:
Talk given at the Sakata Memorial Workshop on "Origin of Mass and Strong-Coupling Gauge Theories" 3-6 March 2015, Nagoya University
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.05173 [pdf]
Int.J.Mod.Phys.A(2017)·4 citations
08
[Submitted on 18 Jul 2015] (cross-list from hep-ph)
$D ˉ Σ_{c}^{*}$ and $D ˉ^{*} Σ_{c}$ interactions and the LHCb hidden-charmed pentaquarks
Jun He🇨🇳
Very recently, two hidden-charmed resonances $P_{c} (4380)$ and $P_{c} (4450)$ consistent with pentaquark states were observed at the LHCb detector. The two $P_{c}$ states locate just below the $D ˉ Σ_{c}^{*}$ and $D ˉ^{*} Σ_{c}$ thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this fact we perform a dynamical investigation about the $D ˉ Σ_{c}^{*} (2520)$ and $D ˉ^{*} Σ_{c} (2455)$ interactions which are described by the meson exchanges. A bound state which carries spin-parity $J^{P} = 3/ 2^{-}$ is produced from the $D ˉ Σ_{c}^{*} (2520)$ interaction, which is consistent with the $P_{c} (4380)$ observed at the LHCb detector. From the $D^{*} Σ_{c} (2455)$ interaction, a bound state with $5/ 2^{+}$ is produced, which can be related to the $P_{c} (4450)$ . The results suggest that the $P_{c} (4380)$ and $P_{c} (4450)$ are good candidates of $D ˉ Σ_{c}^{*} (2520)$ and $D ˉ^{*} Σ_{c} (2455)$ molecular states, respectively.
Comments:
5 pages, 3 figures, published version in Phys. Lett. B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1507.05200 [pdf]
PLB(2016)·256 citations
09
[Submitted on 19 Jul 2015] (cross-list from nucl-ex)
Centrality and transverse momentum dependence of elliptic flow of multi-strange hadrons and $ϕ$ meson in Au+Au collisions at $s_{N N}$ = 200 GeV
STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · A. Aparin · D. Arkhipkin · E. C. Aschenauer · G. S. Averichev · X. Bai · V. Bairathi and 323 other authors
We present high precision measurements of elliptic flow near midrapidity ( $∣ y ∣ < 1.0$ ) for multi-strange hadrons and $ϕ$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $s_{N N} =$ 200 GeV. We observe that the transverse momentum dependence of $ϕ$ and $Ω$ $v_{2}$ is similar to that of $π$ and $p$ , respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30 $%$ and 30-80 $%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $ϕ$ and proton $v_{2}$ at low transverse momentum in the 0-30 $%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$ .
Comments:
7 pages and 4 figures, Accepted for publication in Physical Review Letters
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.05247 [pdf]
PRL(2016)·120 citations
10
[Submitted on 20 Jul 2015] (cross-list from hep-ph)
Understanding the newly observed heavy pentaquark candidates
Xiao-Hai Liu🇯🇵 · Qian Wang🇩🇪 · Qiang Zhao🇨🇳
We find that several thresholds can contribute to the enhancements of the newly observed heavy pentaquark candidates $P_{c}^{+} (4380)$ and $P_{c}^{+} (4450)$ via the anomalous triangle singularity (ATS) transitions in the specific kinematics of $Λ_{b} \to J / ψ K^{-} p$ . Apart from the observed two peaks we find that another peaks around 4.5 GeV can also be produced by the ATS. We also show that the $Σ_{c}^{(*)}$ can be produced at leading order in $Λ_{b}$ decay. This process is different from the triangle diagram and its threshold enhancement only appears as CUSP effects if there is no pole structure or the ATS involved. The threshold interaction associated with the presence of the ATS turns out to be a general phenomenon and plays a crucial role in the understanding of candidates for exotic states.
Comments:
9 pages, 6 figures, 4 tables; published version in PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1507.05359 [pdf]
PLB(2016)·288 citations
11
[Submitted on 20 Jul 2015] (cross-list from astro-ph.SR)
Landau quantization and mass-radius relation of magnetized White Dwarfs in general relativity
Somnath Mukhopadhyay🇮🇳 · Debasis Atta🇮🇳 · D.N. Basu🇮🇳
Recently, several white dwarfs have been proposed with masses significantly above the Chandrasekhar limit, known as Super-Chandrasekhar White Dwarfs, to account for the overluminous Type Ia supernovae. In the present work, Equation of State of a completely degenerate relativistic electron gas in magnetic field based on Landau quantization of charged particles in a magnetic field is developed. The mass-radius relations for magnetized White Dwarfs are obtained by solving the Tolman-Oppenheimer-Volkoff equations. The effects of the magnetic energy density and pressure contributed by a density-dependent magnetic field are treated properly to find the stability configurations of realistic magnetic White Dwarf stars.
Comments:
8 pages including 4 Tables & 4 figures; Typographical error of Eqn.(29) is corrected and 3 new Refs. added in this version
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1507.05439 [pdf]
Rom.Rep.Phys.(2017)·10 citations
12
[Submitted on 20 Jul 2015] (cross-list from hep-ph)
Initial state fluctuations from mid-peripheral to ultra-central collisions in a event-by-event transport approach
Salvatore Plumari🇮🇹 · Giovanni Luca Guardo🇮🇹 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹
We have developed a relativistic kinetic transport approach that incorporates initial state fluctuations allowing to study the build up of elliptic flow $v_{2}$ and high order harmonics $v_{3}$ , $v_{4}$ and $v_{5}$ for a fluid at fixed $η / s (T)$ . We study the effect of the $η / s$ ratio and its T dependence on the build up of the $v_{n} (p_{T})$ for two different beam energies: RHIC for Au+Au at $s = 200 G e V$ and LHC for $P b + P b$ at $s = 2.76 T e V$ . We find that for the two different beam energies considered the suppression of the $v_{n} (p_{T})$ due to the viscosity of the medium have different contributions coming from the cross over or QGP phase. Our study reveals that only in ultra-central collisions ( $0 - 0.2%$ ) the $v_{n} (p_{T})$ have a stronger sensitivity to the T dependence of $η / s$ in the QGP phase and this sensitivity increases with the order of the harmonic n. Moreover, the study of the correlations between the initial spatial anisotropies $ϵ_{n}$ and the final flow coefficients $v_{n}$ shows that at LHC energies there is more correlation than at RHIC energies. The degree of correlation increases from peripheral to central collisions, but only in ultra-central collisions at LHC, we find that the linear correlation coefficient $C (n, n) \approx 1$ for $n = 2, 3, 4$ and $5$ . This suggests that the final correlations in the ( $v_{n}$ , $v_{m}$ ) space reflect the initial correlations in the ( $ϵ_{n}$ , $ϵ_{m}$ ) space.
Comments:
Minor changes. Published on Phys. Rev. C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.05540 [pdf]
PRC(2015)·72 citations

Affiliations

first authorsco-authorsvia INSPIRE