Nuclear Theory·nucl-th

Monday·July 16, 2018

18 papers—12 primary·6 cross-listed

01
[Submitted on 13 Jul 2018]
Heavy-flavor nuclear modification factor and event-by-event azimuthal anisotropy correlations in heavy ion collisions
Caio Alves Garcia Prado🇧🇷
Relativistic heavy ion collisions, which are performed at large experimental programs such as Relativistic Heavy Ion Collider's (RHIC) STAR experiment and the Large Hadron Collider's (LHC) experiments, can create an extremely hot and dense state of the matter known as the quark gluon plasma (QGP). A huge amount of sub-nucleonic particles are created in the collision processes and their interaction and subsequent evolution after the collision takes place is at the core of the understanding of the matter that builds up the Universe. It has recently been shown that event-by-event fluctuations in the spatial distribution between different collision events have great impact on the particle distributions that are measured after the evolution of the created system. Specifically, these distributions are greatly responsible for generating the observed azimuthal anisotropy in measurements. Furthermore, the eventual cooling and expansion of the fluctuating system can become very complex due to lumps of energy density and temperature, which affects the interaction of the particles that traverse the medium. In this configuration, heavy flavor particles play a special role, as they are generally created at the initial stages of the process and have properties that allow them to retain "memory" from the interactions within the whole evolution of the system. However, the comparison between experimental data and theoretical or phenomenological predictions on the heavy flavor sector cannot fully explain the heavy quarks coupling with the medium and their subsequent hadronization process. [Full abstract in file]
Comments:
PhD. Thesis submitted to Instituto de Física for the degree of Doctor of Phylosophy in Physics in August, 2017. 102 pages, 39 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.04885 [pdf]
2 citations
02
[Submitted on 13 Jul 2018]
Relativistic hydrodynamics with spin
W. Florkowski🇵🇱 · B. Friman🇩🇪 · A. Jaiswal🇮🇳 · R. Ryblewski🇵🇱 · E. Speranza🇩🇪
A newly proposed framework of perfect-fluid relativistic hydrodynamics for particles with spin 1/2 is briefly reviewed. The hydrodynamic equations follow entirely from the conservation laws for energy, momentum, and angular momentum. The incorporation of the angular-momentum conservation requires that the spin polarization tensor is introduced. It plays a role of a Lagrange multiplier conjugated to the spin tensor. The space-time evolution of the spin polarization tensor depends on the specific form chosen for the spin tensor.
Comments:
contribution to the Quark Matter 2018 conference proceedings
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04946 [pdf]
NPA(2019)·6 citations
03
[Submitted on 13 Jul 2018]
Role of breakup processes in deuteron-induced spallation reactions at 100-200 MeV/nucleon
Shinsuke Nakayama · Naoya Furutachi · Osamu Iwamoto · Yukinobu Watanabe
Use of deuteron-induced spallation reactions at intermediate energies has recently been proposed for transmutation of several long-lived fission products (LLFPs). In the design study of a transmutation system using a deuteron primary beam, accurate cross section data of deuteron-induced reactions on the LLFPs are indispensable. Reliable model predictions play an important role in completing the necessary cross section data since currently available experimental data are very limited. Under the circumstances, we have been developing a code system dedicated for deuteron-induced reactions, which is called DEURACS. Aiming to predict the production cross sections of residual nuclei, the purpose of the present work is to clarify a role of deuteron breakup processes in deuteron-induced spallation reactions at intermediate energies. Isotopic production cross sections of residual nuclei in the deuteron-induced reactions on 93Zr and 107Pd at 100-200 MeV/nucleon are analyzed using DEURACS, in which the breakup processes are explicitly taken into account. The calculated cross sections are decomposed into individual components corresponding to the absorption of either neutron or proton in the incident deuteron, or the deuteron itself. The calculated cross sections reproduced the experimental data well over a wide mass number range of residual nuclei. From a component-by-component analysis, it was found that the components of nucleon absorption have the significant contributions to the production of residual nuclei. Consideration of the breakup processes is essential to predict the production cross sections of residual nuclei in deuteron-induced reactions. The framework of DEURACS is applicable to deuteron-induced spallation reactions at intermediate energies.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04947 [pdf]
PRC(2018)·8 citations
04
[Submitted on 13 Jul 2018]
First order Coriolis-coupling for rotational spectrum of a tetrahedrally-deformed core plus one-particle system
Shingo Tagami🇯🇵 · Yoshifumi R. Shimizu🇯🇵 · Jerzy Dudek🇫🇷
The possible existence of shape-coexisting nuclear configurations with tetrahedral symmetry is receiving an increasing attention due to unprecedented nuclear structure properties, in particular in terms of the exotic 4-fold nucleonic level degeneracies and the expected long lifetimes which may become a new decisive argument in the exotic nuclei research programs. The present article addresses the rotational structure properties of the tetrahedrally-symmetric even-even core configurations coupled with a single valence nucleon. We focus on the properties of the associated Coriolis-coupling Hamiltonian proposing the solutions based on the explicit construction of the bases of the irreducible representations of the tetrahedral point-group on the one-hand side and the microscopic angular-momentum and parity projection nuclear mean-field approach on the other. It is shown that for one-particle occupying an orbital belonging to the $E_{1/2}$ or $E_{5/2}$ irreducible representation, the rotational spectrum splits into two sequences, the structures analogous to those of the $K = 1/2$ rotational bands in the axially symmetric nuclei. Although the spectrum is generally more complicated for one-particle occupying a 4-fold degenerate orbital belonging to the $G_{3/2}$ representation, an appearance of the correlated double-sequence structures persists. The spectra of the doubly-magic tetrahedral core plus one-particle systems can be well interpreted using the analytical solutions of the first order Coriolis-coupling Hamiltonian. We introduce the notion of the generalized decoupling parameters, which determine the size of the energy-splitting between the double-sequence structures.
Comments:
to appear in Physical Review C; several misprints corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04967 [pdf]
PRC(2018)·5 citations
05
[Submitted on 13 Jul 2018]
Shrunk halo and quenched shell gap at $N = 16$ in $^{22}$ C: Inversion of $s d$ states and deformation effects
Xiang-Xiang Sun · Jie Zhao · Shan-Gui Zhou
We investigate the ground state properties of $^{22}$ C by using a deformed relativistic Hartree-Bogoliubov model in continuum and explore the interplays among the formation of a halo, deformation effects, the inversion of $s d$ states, the shell evolution, and changes of nuclear magicities. It is revealed that there is an inversion between the two spherical orbitals $2 s_{1/2}$ and $1 d_{5/2}$ in $^{22}$ C compared with the conventional single particle shell structure in stable nuclei. This inversion, together with deformation effects, results in a shrunk halo and a quenched shell gap at $N = 16$ . It is predicted that the core of $^{22}$ C is oblate but the halo is prolate. Therefore several exotic nuclear phenomena, including the halo, the shape decoupling effects, the inversion of $s d$ states, and the evolution of shell structure which results in (dis)appearance of magic numbers, coexist in one single nucleus $^{22} C$ .
Comments:
Phys. Lett. B, in press
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.04991 [pdf]
PLB(2018)·110 citations
06
[Submitted on 13 Jul 2018]
Longitudinal fluctuations and decorrelations of anisotropic flows in relativistic heavy-ion collisions
Xiang-Yu Wu🇨🇳 · Long-Gang Pang🇺🇸 · Guang-You Qin🇨🇳 · Xin-Nian Wang🇨🇳
We study the longitudinal decorrelations of elliptic, triangular and quadrangular flows in heavy-ion collisions at the LHC and RHIC energies. The event-by-event CLVisc (3+1)-dimensional hydrodynamics model, combined with the fully fluctuating AMPT initial conditions, is utilized to simulate the space-time evolution of the strongly-coupled quark-gluon plasma. Detailed analysis is performed for the longitudinal decorrelations of flow vectors, flow magnitudes and flow orientations. We find strong correlations between final-state longitudinal decorrelations of anisotropic flows and initial-state longitudinal structures and collision geometry: while the decorrelation of elliptic flow shows a non-monotonic centrality dependence due to initial elliptic geometry, typically the longitudinal flow decorrelations are larger in lower energy and less central collisions where the mean lengths of the string structure are shorter in the initial states.
Comments:
4 pages, 3 figures, Proceedings of Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1807.04995 [pdf]
NPA(2019)·2 citations
07
[Submitted on 13 Jul 2018]
Non-Equilibrium Quantum Transport of Chiral Fluids from Kinetic Theory
Yoshimasa Hidaka🇯🇵 · Shi Pu🇯🇵 · Di-Lun Yang🇯🇵
We introduce the quantum-field-theory (QFT) derivation of chiral kinetic theory (CKT) from the Wigner-function approach, which manifests side jumps and non-scalar distribution functions associated with Lorentz covariance and incorporates both background fields and collisions. The formalism is utilized to investigate second-order responses of chiral fluids near local equilibrium. Such non-equilibrium anomalous transport is dissipative and affected by interactions. Contributions from both quantum corrections in anomalous hydrodynamic equations (EOM) of motion and those from the CKT and Wigner functions (WF) are considered in a relaxation-time approximation (RTA). Anomalous charged Hall currents engendered by background electric fields and temperature/chemical-potential gradients are obtained. Furthermore, chiral magnetic/vortical effects (CME/CVE) receive viscous corrections as non-equilibrium modifications stemming from the interplay between side jumps, magnetic-moment coupling, and chiral anomaly.
Comments:
4 pages, 1 figure, Quark Matter 2018 Proceedings, parallel talk presented by Di-Lun Yang
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1807.05018 [pdf]
NPA(2019)·19 citations
08
[Submitted on 12 Jul 2018]
$Υ$ suppression in a hadron gas
L. M. Abreu🇧🇷 · F. S. Navarra🇧🇷 · M. Nielsen🇧🇷
In this work we study the interactions of bottom mesons which lead to $Υ$ production and absorption in hot hadronic matter. We use effective Lagrangians to calculate the $Υ$ production cross section in processes such as $B ˉ^{(*)} + B^{(*)} \to Υ + (π, ρ)$ and also the $Υ$ absorption cross section in the corresponding inverse processes. We update and extend previous calculations by Lin and Ko, introducing anomalous interactions. The obtained cross sections are used as input to solve the rate equation which allows us to follow the time evolution of the $Υ$ multiplicity. In contrast to previous conjectures, our results suggest that the interactions in the hadron gas phase strongly reduce the $Υ$ abundance.
Comments:
11 pages, 8 figures. arXiv admin note: text overlap with arXiv:1712.06019; text overlap with arXiv:1708.02913 by other authors
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05081 [pdf]
PRC(2020)·18 citations
09
[Submitted on 13 Jul 2018]
Theoretical study of the $Δ^{++} - Δ^{-}$ configuration in the deuteron using antiproton beam
A.B. Larionov🇩🇪 · A. Gillitzer🇩🇪 · J. Haidenbauer🇩🇪 · M. Strikman🇺🇸
We study the manifestation of the $Δ^{++} - Δ^{-}$ component of the deuteron wave function in the exclusive reaction $p ˉ d \to π^{-} π^{-} Δ^{++}$ . Due to the large binding energy the internal motion in the $Δ - Δ$ system is relativistic. We take this into account within the light-cone (LC) wave function formalism and, indeed, found large differences between calculations based on the LC and non-relativistic (NR) wave functions. We demonstrate, that the consistent LC treatment of the $Δ - Δ$ system plays the key role in the separation of the signal and background. Within the LC approach, the characteristic shape of the momentum distribution of the $Δ - Δ$ bound system predicted by the meson-exchange model is well visible on the background of usual annihilations at beam momenta between 10 and 15 GeV/c.
Comments:
44 pages, 21 figures, sect. 3 extended, references added, results unchanged, accepted in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05105 [pdf]
PRC(2018)·8 citations
10
[Submitted on 13 Jul 2018]
Dynamical initialization and hydrodynamic modeling of relativistic heavy-ion collisions
Chun Shen🇺🇸 · Björn Schenke🇺🇸
We present a fully three-dimensional model providing initial conditions for energy and conserved charge density distributions in heavy ion collisions at RHIC Beam Energy Scan (BES) collision energies. The model includes the dynamical deceleration of participating nucleons or valence quarks. It provides a realistic estimation of the initial baryon stopping during the early stage of collisions. We also present the implementation of the model with 3+1 dimensional hydrodynamics, which involves the addition of source terms that deposit energy and net-baryon densities produced by the initial state model at proper times greater than the initial time for the hydrodynamic simulation. The importance of this dynamical initialization stage on hadronic flow observables at the RHIC BES is quantified.
Comments:
4 pages, 3 figures, conference proceeding for Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05141 [pdf]
NPA(2019)·35 citations
11
[Submitted on 13 Jul 2018]
Impact of alternative transmission coefficient parameterizations on Hauser-Feshbach theory
David A. Brown🇺🇸 · Gustavo P.A. Nobre🇺🇸 · Michal W. Herman🇺🇸
We investigate different formulations of the transmission coefficient $T_{c}$ , including the form implied by Moldauer's ``sum rule for resonance reactions'' [P.A. Moldauer, Phys. Rev. Lett. 19, 1047 (1967)], the SPRT method [G. Noguere, et al. EPJ Web Conf. 146, 02036 (2017)] and the Moldauer-Simonius form [M. Simonius, Phys. Lett. 52B, 279 (1974); P.A. Moldauer, Phys. Rev. 157, 907 (1967)]. Within these different formulations, we compute the neutron transmission coefficients in the resolved and unresolved resonance regions, allowing a direct comparison with the transmission coefficients computed using an optical model potential. For nuclei for which there are no measured resonances, these approaches allow one to predict the average neutron resonance parameters directly from the optical model and level densities. Some of the approaches are valid in both the strong and weak coupling limits (i.e., any value of the average width and mean level spacing). Finally, both the Moldauer-Simonius and Moldauer's Sum Rule forms approaches suggest that superradiance, that is, the quantum chaotic enhancement of certain channels, may be a common phenomena in nuclear collisions. Our results suggest why superradiance has been previously overlooked. We apply our approach to neutron reactions on the closed shell $^{90}$ Zr nucleus and the mid-shell $^{197}$ Au nucleus.
Comments:
12 pages, 6 figures, to be submitted to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05156 [pdf]
PRC(2018)·1 citation
12
[Submitted on 13 Jul 2018]
Features of the IP-Glasma
Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Prithwish Tribedy🇺🇸
We discuss differences between the IP-Glasma model and typical wounded-nucleon model like initial conditions. We point out that the IP-Glasma initial state is more compact in the transverse plane and produces a significant initial flow, both of which contribute to an increased radial flow in the subsequent hydrodynamic evolution. A larger bulk viscosity, compared to calculations that use other initial state models, is required to compensate for these effects and find agreement with experimental data. We further demonstrate the importance of the initial momentum anisotropy of the glasma for anisotropy measures in small collision systems such as p+Pb.
Comments:
4 pages, 2 figures, Proceedings of the 27th international conference on ultra-relativistic nucleus-nucleus collisions (Quark Matter 2018), Venice, Italy, May 13-19 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05205 [pdf]
NPA(2019)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE