Nuclear Theory·nucl-th

Monday·January 19, 2015

13 papers—8 primary·5 cross-listed

01
Possible observables for the chiral electric separation effect in Cu + Au collisions
Guo-Liang Ma🇨🇳 · Xu-Guang Huang🇨🇳
The quark-gluon plasma (QGP) generated in relativistic heavy-ion collisions could be locally parity-odd. In parity-odd QGP, the electric field may induce a chiral current which is called the chiral electric separation effect (CESE). We propose two possible observables for CESE in Cu + Au collisions: The first one is the correlation $ζ_{α β} = ⟨ cos [2 (ϕ_{α} + ϕ_{β} - 2 Ψ_{RP})]⟩$ ; the second one is the charge-dependent event-plane angle $Ψ_{2}^{q}$ with $q = \pm$ being charge. Nonzero $Δ ζ = ζ_{o pp} - ζ_{s am e}$ and $ΔΨ = ⟨ ∣ Ψ_{2}^{+} - Ψ_{2}^{-} ∣ ⟩$ may signal the CESE in Cu + Au collisions. Within a multiphase transport model, we study how the final state interaction affects these observables. We find that the correlation $γ_{α β} = ⟨ cos (ϕ_{α} + ϕ_{β} - Ψ_{RP})⟩$ is sensitive to the out-of-plane charge separation caused by the chiral magnetic effect and to the in-plane charge separation caused by the in-plane electric field, but it is not sensitive to the CESE. On the other hand, $Δ ζ$ and $ΔΨ$ are sensitive to the CESE. Therefore, we suggest that the future experiments measure the above observables in Cu+Au collisions in order to disentangle different chiral and charge separation mechanisms.
nucl-thhep-phnucl-exPRC(2015)·19 citations
02
The structural evolution in transitional nuclei of mass 80 $\leq$ A $\leq$ 132
M. Bhuyan
In this theoretical study, we report an investigation on the behavior of two neutron separation energy, differential variation of the separation energy and the abnormality in nuclear charge radius along the isotopic and isotonic chains of transition nuclei. We have used relativistic mean field formalism with NL3 and NL3 $^{*}$ forces for this present analysis. The study refers to {\it even-even} nuclei such as Zr, Mo, Ru and Pd with $N$ = 40 $-$ 86, where a rich collective phenomena such as proton radioactivity, cluster or nucleus radioactivity, exotic shapes, {\it Island of Inversion} and etc. are observed. These non-monotonic aspects over the isotopic chain are mainly correlated with the structural properties like shell/sub-shell closures, shape transition, clustering and magicity etc. In addition to these, we have shown the internal configuration of these nuclei to get a further insight into the reason for these discrepancies.
nucl-thPRC(2015)·56 citations
03
On spontaneous fission and alpha-decay half-lives of atomic nuclei
K. Pomorski · M. Warda · A. Zdeb
It is shown, that the Gamow-like model with only one adjustable parameter - radius constant is able to reproduce well the alpha-decay half-lives for all even-even nuclei with the proton number larger than 50. The systematics for odd-A and odd-odd isotopes can be also well described when ones introduces an additional hindrance factor. Similar model based on the W. J. Swiatecki idea from 1955 is developed to reproduce the spontaneous fission half-lives of transactinide nuclei. The achieved accuracy of reproduction of the data is better than that obtained in more advanced theories.
nucl-thPhys.Scripta(2015)·14 citations
04
Using electron scattering to constrain the axial-vector form factor
R. González-Jiménez🇪🇸 · J. A. Caballero🇪🇸 · T. W. Donnelly🇺🇸
We present an analysis of elastic and quasielastic parity-violating (PV) electron scattering processes. These reactions can help to constrain the weak neutral current form factors of the nucleon that play an essential role in the description of neutrino cross sections at intermediate energies. We show that combining information from the analysis of elastic and quasielastic reactions the current knowledge on the strange and axial-vector form factors can be significantly improved.
nucl-thPoS(2015)·2 citations
05
Origin of Temperature of Quark-Gluon Plasma in Heavy Ion Collisions
Xiao-Ming Xu🇨🇳
Initially produced quark-gluon matter at RHIC and LHC does not have a temperature. A quark-gluon plasma has a high temperature. From this quark-gluon matter to the quark-gluon plasma is the early thermalization or the rapid creation of temperature. Elastic three-parton scattering plays a key role in the process. The temperature originates from the two-parton scattering, the three-parton scattering, the four-parton scattering and so forth in quark-gluon matter.
nucl-thhep-phhep-th0 citations
06
Four-body correlations in nuclei
M. Sambataro · N. Sandulescu
Low-energy spectra of 4 $n$ nuclei are described with high accuracy in terms of four-body correlated structures ("quartets"). The states of all $N \geq Z$ nuclei belonging to the $A = 24$ isobaric chain are represented as a superposition of two-quartet states, with quartets being characterized by isospin $T$ and angular momentum $J$ . These quartets are assumed to be those describing the lowest states in $^{20}$ Ne ( $T_{z}$ =0), $^{20}$ F ( $T_{z}$ =1) and $^{20}$ O ( $T_{z}$ =2). We find that the spectrum of the self-conjugate nucleus $^{24}$ Mg can be well reproduced in terms of $T$ =0 quartets only and that, among these, the $J$ =0 quartet plays by far the leading role in the structure of the ground state. The same conclusion is drawn in the case of the three-quartet $N = Z$ nucleus $^{28}$ Si. As an application of the quartet formalism to nuclei not confined to the $s d$ shell, we provide a description of the low-lying spectrum of the proton-rich $^{92}$ Pd. The results achieved indicate that, in 4 $n$ nuclei, four-body degrees of freedom are more important and more general than usually expected.
nucl-thPRL(2015)·33 citations
07
Quasielastic electron- and neutrino-nucleus scattering in a continuum random phase approximation approach
V. Pandey🇧🇪 · N. Jachowicz🇧🇪 · T. Van Cuyck🇧🇪 · J. Ryckebusch🇧🇪 · M. Martini🇧🇪
We present a continuum random phase approximation approach to study electron- and neutrino-nucleus scattering cross sections, in the kinematic region where quasielastic scattering is the dominant process. We show the validity of the formalism by confronting inclusive ( $e, e^{'}$ ) cross sections with the available data. We calculate flux-folded cross sections for charged-current quasielastic antineutrino scattering off $^{12}$ C and compare them with the MiniBooNE cross-section measurements. We pay special emphasis to the contribution of low-energy nuclear excitations in the signal of accelerator-based neutrino-oscillation experiments.
nucl-thPoS(2015)·1 citation
08
Constraining the Eq. of State of Super-Hadronic Matter from Heavy-Ion Collisions
Scott Pratt🇺🇸 · Evan Sangaline🇺🇸 · Paul Sorensen🇺🇸 · Hui Wang🇺🇸
The equation of state of QCD matter for temperatures near and above the quark-hadron transition (165 MeV) is inferred within a Bayesian framework through the comparison of data from the Relativistic Heavy Ion Collider and from the Large Hadron Collider to theoretical models. State-of- the-art statistical techniques are applied to simultaneously analyze multiple classes of observables while varying 14 independent model parameters. The resulting posterior distribution over possible equations of state is consistent with results from lattice gauge theory.
nucl-thnucl-exPRL(2015)·228 citations
09
Non-Extensive Quantum Statistics with Particle - Hole Symmetry
T.S. Biro · K.M. Shen · B.W. Zhang
Based on Tsallis entropy and the corresponding deformed exponential function, generalized distribution functions for bosons and fermions have been used since a while. However, aiming at a non-extensive quantum statistics further requirements arise from the symmetric handling of particles and holes (excitations above and below the Fermi level). Naive replacements of the exponential function or cut and paste solutions fail to satisfy this symmetry and to be smooth at the Fermi level at the same time. We solve this problem by a general ansatz dividing the deformed exponential to odd and even terms and demonstrate that how earlier suggestions, like the kappa- and q-exponential behave in this respect.
↳ cond-mat.stat-mechnucl-thPhysica A(2015)·16 citations
10
Charge asymmetry in the differential cross section of high-energy bremsstrahlung in the field of a heavy atom
P.A. Krachkov🇷🇺 · A.I. Milstein🇷🇺
The distinction between the charged particle and antiparticle differential cross sections of high-energy bremsstrahlung in the electric field of a heavy atom is investigated. The consideration is based on the quasiclassical approximation to the wave functions in the external field. The charge asymmetry (the ratio of the antisymmetric and symmetric parts of the differential cross section) arises due to the account for the first quasiclassical correction to the differential cross section. All evaluations are performed with the exact account of the atomic field. We consider in detail the charge asymmetry for electrons and muons. For electrons, the nuclear size effect is not important while for muons this effect should be taken into account. For the longitudinal polarization of the initial charged particle, the account for the first quasiclassical correction to the differential cross section leads to the asymmetry in the cross section with respect to the replacement $φ \to - φ$ , where $φ$ is the azimuth angle between the photon momentum and the momentum of the final charged particle.
↳ hep-phnucl-thphysics.atom-phPRA(2015)·11 citations
11
Leading chiral logarithms for the nucleon mass
Alexey A. Vladimirov🇸🇪 · Johan Bijnens🇸🇪
We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the leading logarithm series for the nucleon mass within the heavy baryon theory. The presented results are the first example of leading logarithm calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass. The talk has been presented at "Quark Confinement and the Hadron Spectrum XI".
↳ hep-phnucl-thAIP Conf.Proc.(2016)·1 citation
12
Supersymmetric inversion of effective-range expansions
Bikashkali Midya · Jérémie Evrard · Sylvain Abramowicz · O. L. Ramírez Suárez · Jean-Marc Sparenberg
A complete and consistent inversion technique is proposed to derive an accurate interaction potential from an effective-range function for a given partial wave in the neutral case. First, the effective-range function is Taylor or Padé expanded, which allows high precision fitting of the experimental scattering phase shifts with a minimal number of parameters on a large energy range. Second, the corresponding poles of the scattering matrix are extracted in the complex wave-number plane. Third, the interaction potential is constructed with supersymmetric transformations of the radial Schrödinger equation. As an illustration, the method is applied to the experimental phase shifts of the neutron-proton elastic scattering in the $^{1} S_{0}$ and $^{1} D_{2}$ channels on the $[0 - 350]$ MeV laboratory energy interval.
↳ quant-phnucl-thphysics.atom-phPRC(2015)·6 citations
13
Antineutrino induced Lambda(1405) production off the proton
Xiulei Ren🇨🇳 · E. Oset🇪🇸 · L. Alvarez-Ruso🇪🇸 · M. J. Vicente Vacas🇪🇸
We have studied the strangeness changing antineutrino induced reactions $ν ˉ_{l} p \to l^{+} ϕB$ , with $ϕB = K^{-} p$ , $K ˉ^{0} n$ , $π^{0} Λ$ , $π^{0} Σ^{0}$ , $η Λ$ , $η Σ^{0}$ , $π^{+} Σ^{-}$ , $π^{-} Σ^{+}$ , $K^{+} Ξ^{-}$ and $K^{0} Ξ^{0}$ , using a chiral unitary approach. These ten coupled channels are allowed to interact strongly, using a kernel derived from the chiral Lagrangians. This interaction generates two $Λ (1405)$ poles, leading to a clear single peak in the $π Σ$ invariant mass distributions. At backward scattering angles in the center of mass frame, $ν ˉ_{μ} p \to μ^{+} π^{0} Σ^{0}$ is dominated by the $Λ (1405)$ state at around 1420~MeV while the lighter state becomes relevant as the angle decreases, leading to an asymmetric line shape. In addition, there are substantial differences in the shape of $π Σ$ invariant mass distributions for the three charge channels. If observed, these differences would provide valuable information on a claimed isospin I=1, strangeness S=-1 baryonic state around 1400 MeV. Integrated cross sections have been obtained for the $π Σ$ and $K ˉ N$ channels, investigating the impact of unitarization in the results. The number of events with $Λ (1405)$ excitation in $ν ˉ_{μ} p$ collisions in the recent antineutrino run at the MINERvA experiment has also been obtained. We find that this reaction channel is relevant enough to be investigated experimentally and to be taken into account in the simulation models of future experiments with antineutrino beams.
↳ hep-phhep-exnucl-thPRC(2015)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE