Nuclear Theory·nucl-th

Tuesday·September 6, 2016

9 papers—5 primary·4 cross-listed

01
[Submitted on 2 Sept 2016]
Novel quantum phenomena induced by strong magnetic fields in heavy-ion collisions
Koichi Hattori🇨🇳 · Xu-Guang Huang🇺🇸
The relativistic heavy-ion collisions create both hot quark-gluon matter and strong magnetic fields, and provide an arena to study the interplay between quantum chromodynamics and quantum electrodynamics. In recent years, it has been shown that such an interplay can generate a number of interesting quantum phenomena in hadronic and quark-gluon matter. In this short review, we first discuss some properties of the magnetic fields in heavy-ion collisions and then give an overview of the magnetic field-induced novel quantum effects. In particular, we focus on the magnetic effect on the heavy flavor mesons, the heavy-quark transports, and the phenomena closely related to chiral anomaly.
Comments:
V2: 47 pages, 21 figures. Review article for Nuclear Science and Techniques. Published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1609.00747 [pdf]
Nucl.Sci.Tech.(2017)·179 citations
02
[Submitted on 3 Sept 2016]
Nuclear mean field and double-folding model of the nucleus-nucleus optical potential
Dao T. Khoa · Nguyen Hoang Phuc · Doan Thi Loan · Bui Minh Loc
Realistic density dependent CDM3Yn versions of the M3Y interaction have been used in an extended Hartree-Fock (HF) calculation of nuclear matter (NM), with the nucleon single-particle potential determined from the total NM energy based on the Hugenholtz-van Hove theorem that gives rise naturally to a rearrangement term (RT). Using the RT of the single-nucleon potential obtained exactly at different NM densities, the density- and energy dependence of the CDM3Yn interactions was modified to account properly for both the RT and observed energy dependence of the nucleon optical potential. Based on a local density approximation, the double-folding model of the nucleus-nucleus optical potential has been extended to take into account consistently the rearrangement effect and energy dependence of the nuclear mean-field potential, using the modified CDM3Yn interactions. The extended double-folding model was applied to study the elastic $^{12}$ C+ $^{12}$ C and $^{16}$ O+ $^{12}$ C scattering at the refractive energies, where the Airy structure of the nuclear rainbow has been well established. The RT was found to affect significantly the real nucleus-nucleus optical potential at small internuclear distances, giving the potential strength close to that implied by the realistic optical model description of the Airy oscillation.
Comments:
Accepted for publication in Physical Review C. arXiv admin note: text overlap with arXiv:1508.05568
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1609.00789 [pdf]
PRC(2016)·49 citations
03
[Submitted on 3 Sept 2016]
Shell plus pairing effect arguments for cluster preformation at the nuclear surface in cold fission
D. N. Poenaru · R. A. Gherghescu
In 1928 G. Gamow as well as Condon and Gurney gave the first explanation of alpha decay as a quantum tunnelling of a preformed particle at the nuclear surface. Soon after experimental discovery in 1984 by Rose and Jones of cluster radioactivity, confirming earlier (1980) predictions by Sandulescu, Poenaru and W. Greiner, a microscopic theory also explained the phenomenon in a similar way. Here we show for the first time that in a spontaneous cold fission process the shell plus pairing corrections calculated with Strutinsky's procedure may give a strong argument for preformation of a light fission fragment near the nuclear surface. It is obtained when the radius of the light fragment, $R_{2}$ , is increased linearly with the separation distance, $R$ , of the two fragments, while for $R_{2} =$ ~constant one gets the well known two hump potential barrier.
Comments:
4 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1609.00847 [pdf]
2 citations
04
[Submitted on 4 Sept 2016]
Theoretical study of the Xi(1620) and Xi(1690) resonances in Xi_c -> pi^+ MB decays
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵 · Makoto Oka🇯🇵 · Juan Nieves🇪🇸 · Eulogio Oset🇪🇸
Nonleptonic weak decays of Xi_c into pi^+ and a meson (M)-baryon (B) final state, MB, are analyzed from the viewpoint of probing S=-2 baryon resonances, i.e. Xi(1620) and Xi(1690), of which spin-parity and other properties are not well known. We argue that the weak decay of Xi_c is dominated by a single quark-line diagram, preferred by the Cabibbo-Kobayashi-Maskawa coefficient, color recombination factor, the diquark correlation, and the kinematical condition. The decay process has an advantage of being free from meson resonances in the pi^+M invariant mass distribution. The invariant mass distribution of the meson-baryon final state is calculated with three different chiral unitary approaches, assuming that the Xi(1620) and Xi(1690) resonances have J^P=1/2^-. It is found that a clear peak for the Xi(1690) is seen in the piXi and KbarLambda spectra. We also suggest that the ratios of the piXi, KbarLambda and KbarSigma final states are useful to distinguish whether the peak is originated from the Xi(1690) resonance or it is a KbarSigma threshold effect.
Comments:
13 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1609.00895 [pdf]
PRC(2017)·67 citations
05
[Submitted on 5 Sept 2016]
Forced canonical thermalization in a hadronic transport approach at high density
Dmytro Oliinychenko🇺🇦 · Hannah Petersen🇩🇪
Hadronic transport approaches based on an effective solution of the relativistic Boltzmann equation are widely applied for the dynamical description of heavy ion reactions at low beam energies. At high densities, the assumption of binary interactions often used in hadronic transport approaches may not be applicable anymore. Therefore, we effectively simulate the high-density regime using the local forced canonical thermalization. This framework provides the opportunity to interpolate in a dynamical way between two different limits of kinetic theory: the dilute gas approximation and the ideal fluid case. This approach will be important for studies of the dynamical evolution of heavy ion collisions at low and intermediate energies as experimentally investigated at the beam energy scan program at RHIC, and in the future at FAIR and NICA. On the other hand, this new way of modelling hot and dense strongly-interacting matter might be relevant for small systems at high energies (LHC and RHIC) as well.
Comments:
23 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1609.01087 [pdf]
J.Phys.G(2017)·17 citations
06
[Submitted on 2 Sept 2016] (cross-list from hep-ph)
Revisiting the equivalence of light-front and covariant QED in the light-cone gauge
Luca Mantovani🇮🇹 · Barbara Pasquini🇮🇹 · Xiaonu Xiong🇮🇹 · Alessandro Bacchetta🇮🇹
We discuss the equivalence between light-front time-ordered-perturbation theory and covariant quantum field theory in light-front quantization, in the case of quantum electrodynamics at one-loop level. In particular, we review the one-loop calculation of the vertex correction, fermion self-energy and vacuum polarization. We apply the procedure of integration by residue over the light-front energy in the loop to show how the perturbative expansion in covariant terms can be reduced to a sum of propagating and instantaneous diagrams of light-front time-ordered perturbation theory. The detailed proof of equivalence between the two formulations of the theory resolves the controversial question on which form should be used for the gauge-field propagator in the light-cone gauge in the covariant approach.
Comments:
18 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.00746 [pdf]
PRD(2016)·14 citations
07
[Submitted on 4 Sept 2016] (cross-list from hep-ph)
First Monte Carlo analysis of fragmentation functions from single-inclusive $e^{+} e^{-}$ annihilation
N. Sato🇺🇸 · J.J. Ethier🇺🇸 · W. Melnitchouk🇺🇸 · M. Hirai🇯🇵 · S. Kumano🇯🇵 · A. Accardi🇺🇸
We perform the first iterative Monte Carlo (IMC) analysis of fragmentation functions constrained by all available data from single-inclusive $e^{+} e^{-}$ annihilation into pions and kaons. The IMC method eliminates potential bias in traditional analyses based on single fits introduced by fixing parameters not well contrained by the data and provides a statistically rigorous determination of uncertainties. Our analysis reveals specific features of fragmentation functions using the new IMC methodology and those obtained from previous analyses, especially for light quarks and for strange quark fragmentation to kaons.
Comments:
44 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1609.00899 [pdf]
PRD(2016)·92 citations
08
[Submitted on 4 Sept 2016] (cross-list from nucl-ex)
Gamma strength function and level density of $^{208}$ Pb from forward-angle proton scattering at 295 MeV
S. Bassauer · P. von Neumann-Cosel · A. Tamii
Gamma strength functions (GSFs) and level densities (LDs) are essential ingredients of statistical nuclear reaction theory with many applications in astrophysics, reactor design, and waste transmutation. The aim of the present work is a test of systematic parametrizations of the GSF recommended by the RIPL-3 data base for the case of $^{208}$ Pb. The upward GSF and LD in $^{208}$ Pb are compared to gamma decay data from an Oslo-type experiment to examine the validity of the Brink-Axel (BA) hypothesis. The E1 and M1 parts of the total GSF are determined from high-resolution forward angle inelastic proton scattering data taken at 295 MeV at RCNP, Osaka, Japan. The total LD in $^{208}$ Pb is derived from the $1^{-}$ LD extracted with a fluctuation analysis in the energy region of the isovector giant dipole resonance. The E1 GSF is compared to parametrizations recommended by the RIPL-3 data base showing systematic deficiencies of all models in the energy region around neutron threshold. The new data for the poorly known spinflip M1 resonance call for a substantial revision of the model suggested in RIPL-3. The total GSF derived from the present data is larger in the PDR energy region than the Oslo data but the strong fluctuations due to the low LD resulting from the double shell closure of $^{208}$ Pb prevent a conclusion on a possible violation of the BA hypothesis. Using the parameters suggested by RIPL-3 for a description of the LD in $^{208}$ Pb with the back-shifted Fermi gas model, remarkable agreement between the two experiments spanning a wide excitation energy range is obtained. Systematic parametrizations of the E1 and M1 GSF parts need to be reconsidered at low excitation energies. The good agreement of LD provides an independent confirmation of the approach underlying the decomposition of GSF and LDs in Oslo-type experiments.
Comments:
7 pages, 8 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1609.00937 [pdf]
PRC(2016)·27 citations
09
[Submitted on 5 Sept 2016] (cross-list from hep-ph)
Structure of charmed baryons studied by pionic decays
Hideko Nagahiro🇯🇵 · Shigehiro Yasui🇯🇵 · Atsushi Hosaka🇯🇵 · Makoto Oka🇯🇵 · Hiroyuki Noumi🇯🇵
We investigate the decays of the charmed baryons aiming at the systematic understanding of hadron internal structures based on the quark model by paying attention to heavy quark symmetry. We evaluate the decay widths from the one pion emission for the known excited states, \Lambda_c^*(2595), \Lambda_c^*(2625), \Lambda_c^*(2765), \Lambda_c^*(2880) and \Lambda_c^*(2940), as well as for the ground states \Sigma_c(2455) and \Sigma_c^*(2520). The decay properties of the lower excited charmed baryons are well explained, and several important predictions for higher excited baryons are given. We find that the axial-vector type coupling of the pion to the light quarks is essential, which is expected from chiral symmetry, to reproduce the decay widths especially of the low lying \Lambda_c^* baryons. We emphasize the importance of the branching ratios of \Gamma(\Sigma_c^*\pi)/\Gamma(\Sigma_c\pi) for the study of the nature of higher excited \Lambda_c^* baryons.
Comments:
20 pages, 5 figures, 11 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.01085 [pdf]
PRD(2017)·91 citations

Affiliations

first authorsco-authorsvia INSPIRE