Nuclear Theory·nucl-th

Tuesday·December 5, 2017

17 papers—8 primary·9 cross-listed

01
[Submitted on 2 Dec 2017]
Neutron Removal from the Deformed Halo 31Ne Nucleus
Juhee Hong · C.A. Bertulani · A.T. Kruppa
Experimental data on Coulomb breakup and neutron removal indicate that 31Ne is one of the heaviest halo nuclei discovered so far. The possible ground state of 31Ne is either 3/2- coming from p-wave halo or 1/2+ from s-wave halo. In this work, we develop a treatable model to include deformed wave functions and a dynamical knockout formalism which includes the dependence on the nuclear orientation to study the neutron removal from 31Ne projectiles at energies around E=200 MeV/nucleon. A detailed account of the effects of deformation on cross sections and longitudinal momentum distributions is made. Our numerical analysis indicates a preference for the 31Ne ground state with spin parity 3/2-.
Comments:
22 pages, 13 figures, accepted for publication in the Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.00639 [pdf]
PRC(2017)·12 citations
02
[Submitted on 4 Dec 2017]
Searching for the Subatomic Swirls in the CuCu and CuAu Collisions
Shuzhe Shi🇺🇸 · Kangle Li🇨🇳 · Jinfeng Liao🇺🇸
Recently the STAR Collaboration discovered the "subatomic swirls", that is, the most vortical fluid flow structures in the quark-gluon plasma produced via the AuAu collisions at the Relativistic Heavy Ion Collider (RHIC). Published in Nature and featured as a cover story, this discovery attracted significant interest and generated wide enthusiasm. For such an important finding, it is crucial to look for independent evidences of confirmation and to critically test the current interpretation of the global polarization measurement. We suggest that the CuCu and CuAu colliding systems at RHIC provide such opportunity. Interestingly, our calculations reveal that the fluid vorticity in the CuCu or CuAu collision is comparable to that in the AuAu Collision. Surprisingly, we find the computed $Λ$ hyperon polarization effect is stronger in the CuCu and CuAu systems than the AuAu system at the same collisional beam energy and centrality class, with an interesting hierarchy CuCu $>$ CuAu $>$ AuAu due to interplay between $Λ$ production timing and the time evolution of the vorticity. These predictions can be readily tested by experimental data.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1712.00878 [pdf]
PLB(2019)·90 citations
03
[Submitted on 4 Dec 2017]
Temperature dependence of transport coefficients of QCD in high-energy heavy-ion collisions
Kazuhisa Okamoto🇯🇵 · Chiho Nonaka🇯🇵
Using our developed new relativistic viscous hydrodynamics code, we investigate the temperature dependence of shear and bulk viscosities from comparison with the ALICE data: single particle spectra and collective flows of Pb+Pb $s_{NN} = 2.76$ TeV collisions at the Large Hadron Collider. We find that from the comprehensive analyses of centrality dependence of single particle spectra and collective flows we can extract detailed information on the quark-gluon plasma bulk property, without the information being smeared by the final state interactions.
Comments:
17 pages, 22 figures, arguments and figures added, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.00923 [pdf]
PRC(2018)·16 citations
04
[Submitted on 4 Dec 2017]
Relation between the Vertex Function and the Propagators in the Pseudovector Coupling Pion-Nucleon System
Susumu Kinpara🇯🇵
The procedure for deriving the Ward-Takahashi identity is applied to the pseudovector coupling pion-nucleon system in which the isovector and axial-vector current does not conserved. The relation is given in closed form although it is more complicated than that of the quantum electrodynamics. The application to the propagator has revealed the interesting results.
Comments:
11 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.00930 [pdf]
1 citation
05
[Submitted on 4 Dec 2017]
Pre-equilibrium effects of the hot nuclei de-excitation via GDR emission - theoretical approach
K. Mazurek🇵🇱 · M. Ciemala🇵🇱 · M. Kmiecik🇵🇱 · A. Maj🇵🇱 · D. Lacroix🇫🇷
The hot rotating nuclei could be formed in the complete and incomplete fusion reaction of two heavy ions. At low bombarding energies the reaction goes via compound nucleus formation and subsequent evaporation of charged particles, neutrons and $γ$ -rays. However, with increasing the energy of the projectile, the emission of particles during the equilibration process becomes more and more probable. This effect can be estimated by the Heavy-Ion Phase-Space Exploration (HIPSE) code which describes the production of clusters of various size from nucleons initially in the target or projectile. This dynamic evolution finalizes with the compound nuclei, quasi-fission or multi-fragmentation products. The hot rotating nuclei produced in fusion reaction can de-excitate by evaporation of particles and emission of $γ$ -rays from the Giant Dipole Resonance, or by fission into two fragments. These processes, evaporation and fission, are described within statistical codes such as GEMINI++ or in dynamical approaches by solving the transport equations of Langevin type. In the present article we will concentrate on the possible effect of the pre-equilibrium emission on the strength function of the effective Giant Dipole Resonance, which can be described within Thermal Shape Fluctuation Model (TSFM) approach.
Comments:
7 pages, 5 figures, Presented at XXIV Nuclear Physics Workshop, 20-24 September 2017, Kazimierz Dolny, Poland
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.00963 [pdf]
Acta Phys.Polon.Supp.(2018)·0 citations
06
[Submitted on 4 Dec 2017]
Self-consistent account for phonon induced corrections to quadrupole moments of odd nuclei. Pole and non-pole diagrams
E.E. Saperstein · S. Kamerdzhiev · D.S. Krepish · S.V. Tolokonnikov · D. Voitenkov
Recent results of the description of quadrupole moments of odd semi-magic nuclei are briefly reviewed. They are based on the self-consistent theory of finite Fermi systems with account for the phonon-particle coupling (PC) effects. The self-consistent model for describing the PC effects was developed previously for magnetic moments. Account for the non-pole diagrams is an important ingredient of this model. In addition to previously reported results for the odd In and Sb isotopes, which are the proton-odd neighbors of even tin nuclei, we present new results for odd Bi isotopes, the odd neighbors of even lead isotopes. In general, account for the PC corrections makes the agreement with the experimental data significantly better.
Comments:
8 pages, 4 figures. Presented at ICNFP17
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.00982 [pdf]
EPJ Web Conf.(2018)·2 citations
07
[Submitted on 4 Dec 2017]
Sequential fission of highly excited compound nuclei in a 4D Langevin approach
D. Gruyer🇫🇷 · K. Mazurek🇵🇱 · J. D. Frankland🇫🇷 · E. Bonnet🇫🇷 · P. N. Nadtochy🇷🇺 · A. Chbihi🇫🇷 · J.P. Wieleczko🇫🇷
In highly dissipative collisions between heavy ions, the optimal conditions to investigate different de-excitation channels of hot nuclei such as evaporation, fission or multifragmentation are well known. One crucial issue remains the excitation energy region where fission gives way to multifragmentation. In this paper, the onset of multi-fragment exit channels is investigated in terms of sequential fission. For the first time, the dynamical approach based on solving Langevin transport equations in multidimensional collective coordinate space is used to follow the de-excitation of highly excited (up to E* =223-656 MeV) 248Rf compound nuclei. The sequential fission model we propose contains two steps: (1) time evolution of the compound nucleus up to either scission or residue formation, followed by (2) dynamical calculations of each primary fragment separately. This procedure allows to obtain from one to four cold fragments correlated with the light particles emitted during the de-excitation process. Experimental data measured with the INDRA detector for the 129Xe+ natSn reaction at beam energies 8, 12 and 15 MeV/nucleon provide strong constraints for this sequential fission scenario.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1712.00999 [pdf]
0 citations
08
[Submitted on 4 Dec 2017]
Large directed flow of open charm mesons probes the three dimensional distribution of matter in heavy ion collisions
Sandeep Chatterjee🇵🇱 · Piotr Bożek🇵🇱
Thermalized matter created in non-central relativistic heavy-ion collisions is expected to be tilted in the reaction plane with respect to the beam axis. The most notable consequence of this forward-backward symmetry breaking is the observation of rapidity-odd directed flow for charged particles. On the other hand, the production points for heavy quarks are forward-backward symmetric and shifted in the transverse plane with respect to the fireball. The drag of heavy quarks from the asymmetrically distributed thermalized matter generates a large directed flow for heavy flavor mesons. We predict a very large rapidity odd directed flow of $D$ mesons in non-central Au-Au collisions at $s_{N N} = 200$ GeV, $se v er a l$ $t im es$ $l a r g er$ than for charged particles. A possible experimental observation of a large directed flow for heavy flavor mesons would represent an almost direct probe of the 3-dimensional distribution of matter in heavy-ion collisions.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.01189 [pdf]
PRL(2018)·87 citations
09
[Submitted on 1 Dec 2017] (cross-list from hep-ex)
Chiral magnetic effect search in p+Au, d+Au and Au+Au collisions at RHIC
Jie Zhao (for the STAR collaboration)🇺🇸
Metastable domains of fluctuating topological charges can change the chirality of quarks and induce local parity violation in quantum chromodynamics. This can lead to observable charge separation along the direction of the strong magnetic field produced by spectator protons in relativistic heavy-ion collisions, a phenomenon called the chiral magnetic effect (CME). A major background source for CME measurements using the charge-dependent azimuthal correlator ( $Δ γ$ ) is the intrinsic particle correlations (such as resonance decays) coupled with the azimuthal elliptical anisotropy ( $v_{2}$ ). In heavy-ion collisions, the magnetic field direction and event plane angle are correlated, thus the CME and the $v_{2}$ -induced background are entangled. In this report, we present two studies from STAR to shed further lights on the background issue. (1) The $Δ γ$ should be all background in small system p+Au and d+Au collisions, because the event plane angles are dominated by geometry fluctuations uncorrelated to the magnetic field direction. However, significant $Δ γ$ is observed, comparable to the peripheral Au+Au data, suggesting a background dominance in the latter, and likely also in the mid-central Au+Au collisions where the multiplicity and $v_{2}$ scaled correlator is similar. (2) A new approach is devised to study $Δ γ$ as a function of the particle pair invariant mass ( $m_{in v}$ ) to identify the resonance backgrounds and hence to extract the possible CME signal. Signal is consistent with zero within uncertainties at high $m_{in v}$ . Signal at low $m_{in v}$ , extracted from a two-component model assuming smooth mass dependence, is consistent with zero within uncertainties.
Comments:
ISMD 2017 conference proceeding contribution
Subjects:
High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1712.00394 [pdf]
EPJ Web Conf.(2018)·9 citations
10
[Submitted on 1 Dec 2017] (cross-list from astro-ph.HE)
Implications from GW170817 and I-Love-Q relations for relativistic hybrid stars
Vasileios Paschalidis🇺🇸 · Kent Yagi🇺🇸 · David Alvarez-Castillo🇩🇪 · David B. Blaschke🇷🇺 · Armen Sedrakian🇩🇪
Gravitational wave observations of GW170817 placed bounds on the tidal deformabilities of compact stars allowing one to probe equations of state for matter at supranuclear densities. Here we design new parametrizations for hybrid hadron-quark equations of state, that give rise to low-mass twin stars, and test them against GW170817. We find that GW170817 is consistent with the coalescence of a binary hybrid star--neutron star. We also test and find that the I-Love-Q relations for hybrid stars in the third family agree with those for purely hadronic and quark stars within $\sim 3%$ for both slowly and rapidly rotating configurations, implying that these relations can be used to perform equation-of-state independent tests of general relativity and to break degeneracies in gravitational waveforms for hybrid stars in the third family as well.
Comments:
8 pages, 4 figures, 2 tables; matches published version, updated fig. 2
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.00451 [pdf]
PRD(2018)·256 citations
11
[Submitted on 2 Dec 2017] (cross-list from hep-ph)
Meson properties in magnetized quark matter
Ziyue Wang🇨🇳 · Pengfei Zhuang🇨🇳
We study neutral and charged meson properties in magnetic field. Taking bosolization method in a two-flavor Nambu--Jona-Lasinio model, we derive effective meson Lagrangian density with minimal coupling to the magnetic field, by employing derivative expansion for both the meson fields and Schwinger phases. We extract from the effective Lagrangian density the meson curvature, pole and screening masses. As the only Goldstone mode, the neutral pion controls the thermodynamics of the system and propagates the lang range quark interaction. The magnetic field breaks down the space symmetry, and the quark interaction region changes from a sphere in vacuum to a ellipsoid in magnetic field.
Comments:
10 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.00554 [pdf]
PRD(2018)·66 citations
12
[Submitted on 2 Dec 2017] (cross-list from astro-ph.HE)
Cooling of hypernuclear compact stars
Adriana R. Raduta (IFIN-HH)🇷🇴 · Armen Sedrakian (FIAS)🇩🇪 · Fridolin Weber (SDSU)🇺🇸
We study the thermal evolution of hypernuclear compact stars constructed from covariant density functional theory of hypernuclear matter and parameterizations which produce sequences of stars containing two-solar-mass objects. For the input in the simulations, we solve the Bardeen-Cooper-Schrieffer gap equations in the hyperonic sector and obtain the gaps in the spectra of $Λ$ , $Ξ^{0}$ and $Ξ^{-}$ hyperons. For the models with masses $M / M_{⊙} \geq 1.5$ the neutrino cooling is dominated by hyperonic direct Urca processes in general. In the low-mass stars the $(Λ p)$ plus leptons channel is the dominant direct Urca process, whereas for more massive stars the purely hyperonic channels $(Σ^{-} Λ)$ and $(Ξ^{-} Λ)$ are dominant. Hyperonic pairing strongly suppresses the processes on $Ξ^{-}$ s and to a lesser degree on $Λ$ s. We find that intermediate-mass $1.5 \leq M / M_{⊙} \leq 1.8$ models have surface temperatures which lie within the range inferred from thermally emitting neutron stars, if the hyperonic pairing is taken into account. Most massive models with $M / M_{⊙} ≃ 2$ may cool very fast via the direct Urca process through the $(Λ p)$ channel because they develop inner cores where the $S$ -wave pairing of $Λ$ s and proton is absent.
Comments:
v2: minor changes, matches published version, 11 pages, 9 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1712.00584 [pdf]
MNRAS(2018)·63 citations
13
[Submitted on 2 Dec 2017] (cross-list from hep-ph)
Development of heavy-flavour flow-harmonics in high-energy nuclear collisions
Andrea Beraudo🇮🇹 · Arturo De Pace🇮🇹 · Marco Monteno🇮🇹 · Marzia Nardi🇮🇹 · Francesco Prino🇮🇹
We employ the POWLANG transport setup, developed over the last few years, to provide new predictions for several heavy-flavour observables in relativistic heavy-ion collisions from RHIC to LHC center-of-mass energies. In particular, we focus on the development of the flow-harmonics $v_{2}$ and $v_{3}$ arising from the initial geometric asymmetry in the initial conditions and its associated event-by-event fluctuations. Within the same transport framework, for the sake of consistency, we also compare the nuclear modification factor of the $p_{T}$ spectra of charm and beauty quarks, heavy hadrons and their decay electrons. We compare our findings to the most recent data from the experimental collaborations. We also study in detail the contribution to the flow harmonics from the quarks decoupling from the fireball during the various stages of its evolution: although not directly accessible to the experiments, this information can shed light on the major sources of the final measured effect.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.00588 [pdf]
JHEP(2018)·41 citations
14
[Submitted on 3 Dec 2017] (cross-list from hep-ph)
Hadronic Lorentz Violation in Chiral Perturbation Theory Including the Coupling to External Fields
Rasha Kamand🇺🇸 · Brett Altschul🇺🇸 · Matthias R. Schindler🇺🇸
If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level. We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory. Considering a two-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields. The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz violation which depend on linear combinations of quark-level coefficients. In particular, at leading order the electromagnetic couplings depend on the very same combinations as appear in the free particle propagators. This means that observations of electromagnetic processes involving hadrons--such as vacuum Cerenkov radiation, which may be allowed in Lorentz-violating theories--can only reliably constrain certain particular combinations of quark coefficients.
Comments:
21 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1712.00838 [pdf]
PRD(2018)·14 citations
15
[Submitted on 4 Dec 2017] (cross-list from hep-th)
Secular Terms in Dyson Series to All-Orders of Perturbation
Satoshi Iso🇯🇵 · Hikaru Ohta🇯🇵 · Takao Suyama🇯🇵
In classical and quantum systems, perturbation of an evolution equation is often invalidated by secular terms which diverge at late times. The diverging behavior of evolution can be remedied by various techniques of resumma- tion such as renormalization group or multi-scale analysis. In this paper, we prove that, in a generic quantum mechanical system, secular terms can be systematically removed to all orders in the Dyson series by the method of improved (renormalized) perturbation. A recurrence relation to provide an explicit method to remove the secular terms is given. As a byproduct, we give a simple method to obtain energy eigenvalues and decay rates to all orders of perturbation.
Comments:
28 pages
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
1712.00943 [pdf]
PTEP(2018)·2 citations
16
[Submitted on 4 Dec 2017] (cross-list from hep-lat)
Path optimization method for the sign problem
Akira Ohnishi🇯🇵 · Yuto Mori🇯🇵 · Kouji Kashiwa🇯🇵
We propose a path optimization method (POM) to evade the sign problem in the Monte-Carlo calculations for complex actions. Among many approaches to the sign problem, the Lefschetz-thimble path-integral method and the complex Langevin method are promising and extensively discussed. In these methods, real field variables are complexified and the integration manifold is determined by the flow equations or stochastically sampled. When we have singular points of the action or multiple critical points near the original integral surface, however, we have a risk to encounter the residual and global sign problems or the singular drift term problem. One of the ways to avoid the singular points is to optimize the integration path which is designed not to hit the singular points of the Boltzmann weight. By specifying the one-dimensional integration-path as $z = t + i f (t) (f \in R)$ and by optimizing $f (t)$ to enhance the average phase factor, we demonstrate that we can avoid the sign problem in a one-variable toy model for which the complex Langevin method is found to fail. In this proceedings, we propose POM and discuss how we can avoid the sign problem in a toy model. We also discuss the possibility to utilize the neural network to optimize the path.
Comments:
Talk given at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain. 8 pages, 4 figures (references are updated in v2)
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.01088 [pdf]
EPJ Web Conf.(2018)·10 citations
17
[Submitted on 4 Dec 2017] (cross-list from hep-ph)
IR properties of chiral effects in pionic matter
A. Avdoshkin🇷🇺 · A. V. Sadofyev🇷🇺 · V. I. Zakharov🇷🇺
Chiral effects exhibit peculiar universality in idealized theoretical limits. However, they are known to be infrared sensitive and get modified in more realistic settings. In this work, we study how the corresponding conductivities vary with the constituent mass. We concentrate on a pionic realization of chiral effects which provides a better control over infrared properties of the theory. The pionic medium is considered at finite vector and axial isospin chemical potentials in the presence of an external magnetic field. This system supports electric and axial isospin currents along the magnetic field which correspond to chiral magnetic and chiral separation effects. We show that these currents are sensitive to the finite mass of the constituents, but the conductivities follow a simple scaling with the corresponding charge densities as one would expect for polarization effects. It is argued that this relation can capture the dependence of chiral effects on other infrared parameters. Finally, we briefly comment on the realization of the 't Hooft matching condition in pionic media at finite densities.
Comments:
14 pages, version accepted in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1712.01256 [pdf]
PRD(2018)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE