Nuclear Theory·nucl-th

Tuesday·November 13, 2018

13 papers—9 primary·4 cross-listed

01
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.
nucl-thPPNP(2019)·255 citations
02
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.
nucl-thhep-exhep-phnucl-exPRC(2019)·31 citations
03
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 $0_{2}^{+}$ .
nucl-thPRC(2018)·22 citations
04
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.
nucl-thJ.Phys.G(2019)·2 citations
05
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.
nucl-thhep-ph18 citations
06
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.
nucl-th0 citations
07
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.
nucl-thIJMPE(2019)·13 citations
08
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.
nucl-thRuss.Phys.J.(2019)·1 citation
09
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.
nucl-thAdv.Nucl.Phys.(2018)·0 citations

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first authorsco-authorsvia INSPIRE