Nuclear Theory·nucl-th

Tuesday·November 13, 2018

13 papers—9 primary·4 cross-listed

01
[Submitted on 11 Nov 2018]
Relativistic hydrodynamics for spin-polarized fluids
Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Avdhesh Kumar🇵🇱
Recent progress in the formulation of relativistic hydrodynamics for particles with spin one-half is reviewed. We start with general arguments advising introduction of a tensor spin chemical potential that plays a role of the Lagrange multiplier coupled to the spin angular momentum. Then, we turn to a discussion of spin-dependent distribution functions that have been recently proposed to construct a hydrodynamic framework including spin and serve as a tool in phenomenological studies of hadron polarization. Distribution functions of this type are subsequently used to construct the equilibrium Wigner functions that are employed in the semi-classical kinetic equation. The semi-classical expansion elucidates several aspects of the hydrodynamic approach, in particular, shows the ways in which different possible versions of hydrodynamics with spin can be connected by pseudo-gauge transformations. These results point out at using the de~Groot - van~Leeuwen - van~Weert versions of the energy-momentum and spin tensors as the most natural and complete physical variables. Finally, a totally new method is proposed to design hydrodynamics with spin, which is based on the classical treatment of spin degrees of freedom. Interestingly, for small values of the spin chemical potential the new scheme brings the results that coincide with those obtained before. The classical approach also helps us to resolve problems connected with the normalization of the spin polarization three-vector. In addition, it clarifies the role of the Pauli-Lubanski vector and the entropy current conservation. We close our review with several general comments presenting possible future developments of the discussed frameworks.
Comments:
extended version to be published in Progress in Particle and Nuclear Physics, 2019, one author added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04409 [pdf]
PPNP(2019)·255 citations
02
[Submitted on 11 Nov 2018]
Mapping the QCD phase diagram with statistics friendly distributions
Adam Bzdak🇵🇱 · Volker Koch🇺🇸
We demonstrate that the multiplicity distribution of a system located in the vicinity of a first-order phase transition can be successfully measured in terms of its factorial cumulants with a surprisingly small number of events. This finding has direct implications for the experimental search of a QCD phase transition conjectured to be located in the high baryon density region of the QCD phase diagram.
Comments:
6 pages, 3 figures; comments added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1811.04456 [pdf]
PRC(2019)·31 citations
03
[Submitted on 12 Nov 2018]
Shape evolution and coexistence in neutron-deficient Nd and Sm nuclei
J. Xiang · Z. P. Li · W. H. Long · T. Nikšić · D. Vretenar
The evolution of shapes and low-energy shape coexistence is analyzed in neutron-deficient Nd and Sm nuclei, using a five-dimensional quadrupole collective Hamiltonian (5DCH). Deformation energy surfaces, calculated with the relativistic energy density functional PC-PK1 and a separable finite-range pairing interaction, exhibit a transition from spherical shapes near $N = 80$ , to $γ -$ soft shapes, and to prolate deformed minima in lighter isotopes. The corresponding 5DCH model calculation, based on the self-consistent mean-field potentials, reproduces the empirical isotopic trend of characteristic collective observables, and predicts significantly different deformations for the first two $0^{+}$ states in the $N = 74$ isotones $^{134}$ Nd and $^{136}$ Sm. In addition to bands based on the triaxial $γ -$ soft ground state, in excellent agreement with data, the occurrence of a low-energy rotational band is predicted, built on the prolate deformed ( $β \sim 0.4$ ) excited state $0_{2}^{+}$ .
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04574 [pdf]
PRC(2018)·22 citations
04
[Submitted on 12 Nov 2018]
Competition of deformation and neutron-proton pairing in Gamow-Teller transitions for $^{56, 58}$ Ni and $^{62, 64}$ Ni
Eunja Ha · Myung-Ki Cheoun
We investigated effects of neutron-proton ( $n p$ ) pairing correlations comprising isoscalar (IS) and isovector (IV) component on Gamow-Teller (GT) transitions of $^{56, 58, 62, 64}$ Ni by taking into account nuclear deformation in a deformed Woods-Saxon mean field. Our GT calculations based on a deformed Bardeen-Cooper-Schriffer (DBCS) approach have been performed within a deformed quasi-particle random phase approximation (DQRPA) which explicitly includes the deformation as well as all kinds of pairing correlations not only at the DBCS but also at the DQRPA stage. Competition of these two effects, the deformation and the IS spin-triplet and IV spin-singlet component of the $n p$ pairing, is shown to be significant for understanding the GT strength distributions of Ni isotopes.
Comments:
19 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04589 [pdf]
J.Phys.G(2019)·2 citations
05
[Submitted on 12 Nov 2018]
Charmonium ground states in presence of strong magnetic fields
Amruta Mishra🇮🇳 · Pallabi Parui🇮🇳 · Ankit Kumar🇮🇳 · Sourodeep De🇮🇳
The in-medium masses of the lowest S-wave charmonium states (vector meson, $J / ψ$ and pseudoscalar meson, $η_{c}$ ) and P-wave charmonium states (scalar, $χ_{c 0}$ and axialvector $χ_{c 1}$ ) are investigated in magnetized nuclear matter, within the framework of QCD sum rule approach. These are computed from the medium modifications of the scalar as well as twist--2 gluon condensates, obtained from the medium modifications of a scalar dilaton field, within a chiral effective model. The effects of the magnetic field, isospin asymmetry and density on the masses of these charmonium states have been investigated. The modifications of the masses of the P-wave charmonium states ( $χ_{c 0}$ and $χ_{c 1}$ ) are observed to be much larger as compared to those of the S-wave states, $J / ψ$ and $η_{c}$ within the QCD sum rule approach. The effects of the coupling of the spin with the magnetic field are also investigated in the present work, which result in the mixing of the spin zero charmonium state with the longitudinal component of the vector meson. This leads to an increase (drop) in mass of the longitudinal $J / ψ$ ( $η_{c}$ ) for the S-wave states. The effects of the spin-magnetic field interactions are observed to be dominant at high magnetic fields.
Comments:
20 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1811.04622 [pdf]
18 citations
06
[Submitted on 8 Nov 2018]
A Hole torn by QCD Fields
R.S. Longacre🇺🇸
In this paper we determine that a local negative correlation(the Hole) in $Δ η$ $Δ ϕ$ space of Au + Au collisions at $s_{N N}$ =200 GeV is caused by strong color QCD electric and magnetic fields which are present in the Glasma Flux Tubes that are generated by the initial conditions.
Comments:
arXiv admin note: substantial text overlap with arXiv:1001.1132, arXiv:0809.2286, arXiv:1105.5321
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04767 [pdf]
0 citations
07
[Submitted on 9 Nov 2018]
New Theoretical Results for Radiative 3H(p, {\gamma})4He, 3He(2H, {\gamma})5Li, 4He(2H, {\gamma})6Li, 4He(3H, {\gamma})7Li, and 4He(3He, {\gamma})7Be Captures At Astrophysical Energies
Sergey Dubovichenko · Albert Dzhazairov-Kakhramanov · Nataliya Burkova
We have studied the proton-capture reaction 3H(p,{\gamma})4He. It plays a role in the nucleosynthesis of primordial elements in the early Universe leading to the pre-stellar formation of 4He nuclei. All results of our researches and more new data from works show that the contribution of the 3H(p,{\gamma})4He capture reaction into the processes of primordial nucleosynthesis is relatively small. However, it makes sense to consider this process for making the picture complete of the formation of prestellar 4He and clearing of mechanisms of this reaction. Furthermore, we have considered the 3He(2H,{\gamma})5Li reaction in the low energy range in the modified potential cluster model with splitting of orbital states according to Young tableaux and, in some cases, with forbidden states. These reaction also form part of the nucleosynthesis chain of the processes occurring in the early stages of formation of stable stars, and are possible candidates for overcoming the well-known problem of the A = 5 gap in the synthesis of light elements in the primordial Universe. Continuing study we have considered the radiative capture 4He(3He, {\gamma})7Be at superlow energies, which has a undeniable interest for nuclear astrophysics, since it takes part in the proton-proton fusion chain, and new experimental data on the astrophysical S-factors of this process at energies down to 90 keV and 23 keV and data on the radiative capture reaction 4He(3H,{\gamma})7Li down to 50 keV appeared recently. Moreover, radiative capture reactions 4He(3He,{\gamma})7Be and 4He(2H,{\gamma})6Li may have played a certain role in prestellar nucleosynthesis after the Big Bang, when the temperature of the Universe decreased to the value of 0.3 T9.
Comments:
48p., 22 fig., 173 ref., 8 tabl. arXiv admin note: text overlap with arXiv:1606.04617
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04779 [pdf]
IJMPE(2019)·13 citations
08
[Submitted on 9 Nov 2018]
Whether the excited cluster 14N* exists in 15O nucleus?
S.B. Dubovichenko · N.A. Burkova · A.V. Dzhazairov-Kakhramanov
Within the modified potential cluster model with forbidden states effectively taking into account the Pauli Exclusion Principle the astrophysical S-factor of radiative p14N capture to 15O ground state has been calculated. The calculation was performed at the proton energy up to 5 MeV in the center of mass system (c.m.) with taking into account broad resonances up to 3.4 MeV in c.m. To explain reasonably the available experimental data it is required to admit the existence of 14N cluster in excited state 14N* with the excitation energy equal to 5.69 MeV and momentum JP = 1-. It is assumed that in this case the 4D1/2 state wave function of the p14N* clusters relative motion may be used. There was shown that it is succeeded to describe the S-factor of p14N capture in the resonance region only under the assumption that all low-lying resonances at 260(1/2+), 987(3/2+), 1447(1/2+), 2187(3/2+), and 3211(3/2+) keV in c.m. are the 4D1/2 and 4D3/2 scattering waves.
Comments:
7p., 5 nsbl., 2 fig., 31 ref. arXiv admin note: text overlap with arXiv:0906.1097 by other authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04781 [pdf]
Russ.Phys.J.(2019)·1 citation
09
[Submitted on 12 Nov 2018]
Synergy of nuclear data systematics and proxy-SU(3) in planning future experiments in the superheavies mass region
S.K.Peroulis · S.B. Bofos · T.J. Mertzimekis · A. Martinou · D. Bonatsos
Spectroscopic information of hard-to-reach superheavy nuclei can be invaluable in understanding the dynamics of nuclear systems at large values of charge and volume. RIB factories of the next generation, such as FAIR, plan to provide heavy ion beams at high energies to facilitate experimental access to these mass regimes. In preparation of future experimental endeavours, a systematic survey of available nuclear data, mainly energies and reduced transition probabilities/lifetimes of short-lived first 2+ states in even-even isotopes with Z=82, 84, 86 was undertaken. The principle motivation is to trace the competition between collective and single-particle degrees of freedom in the mass area just above Pb (Z=82), an area known to exhibit isomerism, octupole degrees of freedom and shape coexistence. Existing data were compared to the theoretical predictions using the analytical, parameter-free proxy-SU(3) scheme, for neutron numbers N=96-116. The model was further employed to predict currently unknown values for spectroscopic data in series of Pb, Po and Ra isotopes.
Comments:
5 pages, 2 figures, to appear in HNPS: Advances in Nuclear Physics: Proceedings of the 27th Annual Symposium of the Hellenic Nuclear Physics Society (Athens, 2018), ed. T. Mertzimekis, G. Souliotis, and E. Styliaris
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1811.04823 [pdf]
Adv.Nucl.Phys.(2018)·0 citations
10
[Submitted on 9 Nov 2018] (cross-list from hep-ph)
Space-Time Picture of Baryon Stopping in the Color-Glass Condensate
Larry D. McLerran🇺🇸 · Sören Schlichting🇩🇪 · Srimoyee Sen🇺🇸
We discuss baryon stopping in the Color Glass Condensate description of high energy scattering. We consider the scattering of a distribution of valence quarks on an ultra-relativistic sheet of colored charge. We compute the distribution of scattered quarks from a composite projectile, and calculate the baryon currents before and after the collisions and on an event by event basis. We obtain simple analytic estimates of the baryon number compression and rapidity shifts, which in the idealized case of plane wave scattering, produce results that agree with considerations of Anishetty-Koehler-McLerran.
Comments:
Reference added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1811.04089 [pdf]
PRD(2019)·24 citations
11
[Submitted on 10 Nov 2018] (cross-list from hep-ph)
Event Shape Engineering and Multiplicity dependent Study of Identified Particle Production in proton+proton Collisions at $s$ = 13 TeV using PYTHIA8
Arvind Khuntia🇮🇳 · Sushanta Tripathy🇮🇳 · Ashish Bisht🇮🇳 · Raghunath Sahoo🇮🇳
Small system collectivity observed at the LHC energies along with enhancement of strangeness makes high-multiplicity proton+proton (pp) collisions very interesting in order to look for QGP-like features, usually found in heavy-ion collisions. It may be interesting to perform a double differential study of different observables in pp collisions in terms of charged particle multiplicity and event shape in order to understand the new dimensions in high-multiplicity pp physics. We study the correlation between the number of multi-partonic interactions (nMPI), event shape (transverse spherocity) and charged particle multiplicity classes. For the first time, we report the simulation results on the spherocity and charged particle multiplicity dependent study of ( $π^{+} + π^{-}$ ), (K $^{+}$ +K $^{-}$ ), (p+ $p ˉ$ ), K $^{* 0}$ , $ϕ$ and ( $Λ + Λ ˉ$ ) production in pp collisions at $s$ = 13 TeV using PYTHIA8. We explore the event shape and charged particle multiplicity dependence of the transverse momentum ( $p_{T}$ ) spectra, integrated yield, mean transverse momentum ( $⟨ p_{T} ⟩$ ) and particle ratios of the identified particles. This study provides a baseline for exploring the the event topology and final state multiplicity dependence of identified particle production in the LHC pp collisions.
Comments:
Same as published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1811.04213 [pdf]
J.Phys.G(2021)·31 citations
12
[Submitted on 12 Nov 2018] (cross-list from hep-ph)
Does chiral perturbation theory rule out QCD-based solutions to the strong CP problem?
Thomas D. Cohen🇺🇸
The conventional view is that a solution of the strong CP problem lies beyond QCD. A strong argument supporting this view is that the chiral expansion shows that observables depend on theta (unless a quark mass is zero); this eliminates the possibility that theta is physically irrelevant and appears to necessitate an explanation beyond the standard model. However, scenarios that solve the strong CP problem exist that are consistent with known chiral behavior; in these, QCD becomes nonviable as a theory for nonzero theta. Such scenarios appear to be compatible with lattice studies of the topological susceptibility.
Comments:
The paper has been expanded. It now includes a discussion of how evidence for this class of scenario might be obtained
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1811.04833 [pdf]
PRD(2019)·4 citations
13
[Submitted on 12 Nov 2018] (cross-list from hep-ph)
Description of bulk observables in Au+Au collisions at top RHIC energy in the integrated HydroKinetic Model
M. D. Adzhymambetov🇺🇦 · V. M. Shapoval🇺🇦 · Yu. M. Sinyukov🇺🇦
The results on the main bulk observables obtained in the simulations within the integrated hydrokinetic model (iHKM) of Au+Au collisions at the RHIC energy $s_{N N} = 200$ GeV are presented along with the corresponding experimental data from the STAR and the PHENIX collaborations. The simulations include all the stages of the collision process: formation of the initial state, its gradual thermalization and hydrodynamization, viscous relativistic hydro-evolution, system's hadronization and particlization, and, finally, an expansion of the interacting hadron-resonance gas. The model gives a satisfactory description of charged-particle multiplicities, particle number ratios, transverse momentum spectra for pions, kaons, protons and antiprotons, charged-particle $v_{2}$ coefficients, and femtoscopy radii at all collision centralities. It is demonstrated how one can estimate the times of the pion and kaon maximal emission from the femto-scales.
Comments:
17 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1811.04850 [pdf]
NPA(2019)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE