Nuclear Theory·nucl-th

Tuesday·March 14, 2017

8 papers—5 primary·3 cross-listed

01
Successive variational method of the tensor-optimized antisymmetrized molecular dynamics for central interaction in finite nuclei
Takayuki Myo · Hiroshi Toki · Kiyomi Ikeda · Hisashi Horiuchi · Tadahiro Suhara
Tensor-optimized antisymmetrized molecular dynamics (TOAMD) is the basis of the successive variational method for nuclear many-body problem. We apply TOAMD to finite nuclei to be described by the central interaction with strong short-range repulsion, and compare the results with the unitary correlation operator method (UCOM). In TOAMD, the pair-type correlation functions and their multiple products are operated to the AMD wave function. We show the results of TOAMD using the Malfliet-Tjon central potential containing the strong short-range repulsion. Adding the double products of the correlation functions in TOAMD, the binding energies are converged quickly to the exact values of the few-body calculations for s-shell nuclei. This indicates the high efficiency of TOAMD for treating the short-range repulsion in nuclei. We also employ the s-wave configurations of nuclei with the central part of UCOM, which reduces the short-range relative amplitudes of nucleon pair in nuclei to avoid the short-range repulsion. In UCOM, we further perform the superposition of the s-wave configurations with various size parameters, which provides a satisfactory solution of energies close to the exact and TOAMD values.
nucl-thPRC(2017)·23 citations
02
Differential flow correlations in relativistic heavy-ion collisions
Jing Qian🇨🇳 · Ulrich Heinz🇺🇸 · Ronghua He🇨🇳 · Lei Huo🇨🇳
A systematic analysis of correlations between different orders of $p_{T}$ -differential flow is presented, including mode coupling effects in flow vectors, correlations between flow angles (a.k.a. event-plane correlations), and correlations between flow magnitudes, all of which were previously studied with integrated flows. We find that the mode coupling effects among differential flows largely mirror those among the corresponding integrated flows, except at small transverse momenta where mode coupling contributions are small. For the fourth- and fifth-order flow vectors $V_{4}$ and $V_{5}$ we argue that the event plane correlations can be understood as the ratio between the mode coupling contributions to these flows and and the flow magnitudes. We also find that for $V_{4}$ and $V_{5}$ the linear response contribution scales linearly with the corresponding cumulant-defined eccentricities but not with the standard eccentricities.
nucl-thnucl-exPRC(2017)·21 citations
03
Towers of positive parity excited baryons and their mixing in the large $N_{c}$ limit
Cintia Willemyns🇦🇷 · Carlos Schat🇩🇪
We consider configuration mixing for the nonstrange positive parity excited baryons in the $[5 6^{'}, 0^{+}], [56, 2^{+}], [70, 0^{+}]$ and $[70, 2^{+}]$ quark model $S U (6) \times O (3)$ multiplets contained in the $N = 2$ band. Starting from the effective mass operator for these states we show by an explicit calculation that in the large $N_{c}$ limit they fall into six towers of degenerate states labeled by $K = 0, 1, 1^{'}, 2, 2^{'}, 3$ . We find that the mixing of the quark model states is much simpler than what is naively expected. To leading order in $N_{c}$ only states carrying the same $K$ label can mix, which implies that for the spin-flavor states we started with configuration mixing can be parameterized by just two constants, $μ_{K = 1}$ and $μ_{K = 2}$ .
nucl-thhep-lathep-phPRD(2017)·3 citations
04
Quantum analysis of fluctuations of electromagnetic fields in heavy-ion collisions
B.G. Zakharov🇷🇺
We perform quantum calculations of fluctuations of the electromagnetic fields in $AA$ collisions at RHIC and LHC energies. The analysis is based on the fluctuation-dissipation theorem. We find that in the quantum picture the field fluctuations are very small. They turn out to be much smaller than the predictions of the classical Monte-Carlo simulation with the Woods-Saxon nuclear density.
nucl-thhep-phPisma Zh.Eksp.Teor.Fiz.(2017)·6 citations
05
Adiabatic self-consistent collective path in nuclear fusion reactions
Kai Wen · Takashi Nakatsukasa
Collective reaction paths for fusion reactions, $^{16}$ O+ $α$ $\to$ $^{20}$ Ne and $^{16}$ O+ $^{16}$ O $\to$ $^{32}$ S, are microscopically determined, on the basis of the adiabatic self-consistent collective coordinate (ASCC) method. The collective path is maximally decoupled from other intrinsic degrees of freedom. The reaction paths turn out to deviate from those obtained with standard mean-field calculations with constraints on quadrupole and octupole moments. The potentials and inertial masses defined in the ASCC method are calculated along the reaction paths. The sub-barrier fusion cross sections are calculated for these systems. Inertial mass inside the Coulomb barrier may have a significant influence on the fusion cross section at the deep sub-barrier energy.
nucl-thPRC(2017)·15 citations
06
Valence quark contributions for the $γ^{*} N \to N (1440)$ form factors from Light-Front holography
G. Ramalho🇧🇷 · D. Melnikov🇧🇷
The structure of the nucleon and the first radial excitation of the nucleon, the Roper, $N (1440)$ , is studied within the formalism of Light-Front holography. The nucleon elastic form factors and $γ^{*} N \to N (1440)$ transition form factors are calculated under the assumption of the dominance of the valence quark degrees of freedom. Contrary to the previous studies, the bare parameters of the model associated with the valence quark are fixed by the empirical data for large momentum transfer ( $Q^{2}$ ) assuming that the corrections to the three-quark picture (meson cloud contributions) are suppressed. The $γ^{*} N \to N (1440)$ transition form factors are then calculated without any adjustable parameters. Our estimates are compared with results from models based on valence quarks and others. The model compares well with the $γ^{*} N \to N (1440)$ transition form factor data, suggesting that meson cloud effects are not large, except in the region $Q^{2} < 1.5$ GeV $^{2}$ . In particular, the meson cloud contributions for the Pauli form factor are small.
↳ hep-phhep-exnucl-exnucl-thPRD(2018)·28 citations
07
Topology and stability of the Kondo phase in quark matter
Shigehiro Yasui🇯🇵 · Kei Suzuki🇯🇵 · Kazunori Itakura🇯🇵
We investigate properties of the ground state of a light quark matter with heavy quark impurities. This system exhibits the "QCD Kondo effect" where the interaction strength between a light quark near the Fermi surface and a heavy quark increases with decreasing energy of the light quark towards the Fermi energy, and diverges at some scale near the Fermi energy, called the Kondo scale. Around and below the Kondo scale, we must treat the dynamics nonperturbatively. As a typical nonperturbative method to treat the strong coupling regime, we adopt a mean-field approach where we introduce a condensate, the Kondo condensate, representing a mixing between a light quark and a heavy quark, and determine the ground state in the presence of the Kondo condensate. We show that the ground state is a topologically non-trivial state and the heavy quark spin forms the hedgehog configuration in the momentum space. We can define the Berry phase for the ground-state wavefunction in the momentum space which is associated with a monopole at the position of a heavy quark. We also investigate fluctuations around the mean field in the random-phase approximation, and show the existence of (exciton-like) collective excitations made of a hole $h$ of a light quark and a heavy quark $Q$ .
↳ hep-phcond-mat.str-elnucl-thPRD(2017)·22 citations
08
Quark spin polarization and spontaneous magnetization in high density quark matter
Y. Tsue (Kochi Univ., Japan)🇯🇵 · J. da Providencia (Univ. de Coimbra, Portugal)🇵🇹 · C. Providencia (Univ. de Coimbra, Portugal)🇵🇹 · H. Matsuoka (Kochi Univ., Japan)🇯🇵 · M. Yamamura (Kansai Univ., Japan)🇯🇵 · H. Bohr (Danish Technical Univ., Denmark)🇩🇰
By using the Nambu-Jona-Lasinio model with a tensor-type four-point interaction between quarks, it is shown that there exists a possibility of a spin polarized phase in quark matter at finite temperature and density. When there exists the spin polarization, the spontaneous magnetization may occur if the effect of the anomalous magnetic moment of quark is taken into account. An implication to the compact star objects with strong magnetic field is discussed when the spin polarization occurs.
↳ hep-phnucl-thPoS(2017)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE