Nuclear Theory·nucl-th

Tuesday·September 29, 2015

17 papers—11 primary·6 cross-listed

01
[Submitted on 25 Sept 2015]
Hadronic resonance production and interaction in partonic and hadronic matter in EPOS3 with and without the hadronic afterburner UrQMD
A. G. Knospe🇺🇸 · C. Markert🇺🇸 · K. Werner🇫🇷 · J. Steinheimer🇩🇪 · M. Bleicher🇩🇪
We study the production of hadronic resonances and their interaction in the partonic and hadronic medium using the EPOS3 model, which employs the UrQMD model for the description of the hadronic phase. We investigate the centrality dependence of the yields and momentum distributions for various resonances (rho(770),K(892),phi(1020),Delta(1232),Sigma(1385),Lambda(1520),Xi(1530) and their antiparticles) in Pb-Pb collisions at sNN= 2.76 TeV. The predictions for K(892) and phi(1020) will be compared with the experimental data from the ALICE collaboration. The observed signal suppression of the K(892) with increasing centrality will be discussed with respect to the resonance interaction in the hadronic medium. The mean transverse momentum and other particle ratios such as phi(1020)/p and Omega/phi(1020) will be discussed with respect to additional contributions from the hadronic medium interactions.
Comments:
12 pages, 16 fig
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.07895 [pdf]
PRC(2016)·139 citations
02
[Submitted on 25 Sept 2015]
Asymmetry energy of nuclear matter: Temperature and density dependence, and validity of semi-empirical formula
G. H. Bordbar · R. Feridoonnezhad · M. Taghizade
In this work, we have done a completely microscopic calculation using a many-body variational method based on the cluster expansion of energy to compute the asymmetry energy of nuclear matter. In our calculations, we have employed the $A V_{18}$ nuclear potential. We have also investigated the temperature and density dependence of asymmetry energy. Our results show that the asymmetry energy of nuclear matter depends on both density and temperature. We have also studied the effects of different terms in the asymmetry energy of nuclear matter. These investigations indicate that at different densities and temperatures, the contribution of parabolic term is very substantial with respect to the other terms. Therefore, we can conclude that the parabolic approximation is a relatively good estimation, and our calculated binding energy of asymmetric nuclear matter is in a relatively good agreement with that of semi-empirical mass formula. However, for the accurate calculations, it is better to consider the effects of other terms.
Comments:
11 pages, 1 figure, 3 tables
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1509.07896 [pdf]
Rom.J.Phys.(2015)·1 citation
03
[Submitted on 25 Sept 2015]
Influence of spin polarizability on liquid gas phase transition in the nuclear matter
Z. Rezaei · M. Bigdeli · G. H. Bordbar
In this paper, we investigate the liquid gas phase transition for the spin polarized nuclear matter. Applying the lowest order constrained variational (LOCV) method, and using two microscopic potentials, $A V_{18}$ and $U V_{14}$ +TNI, we calculate the free energy, equation of state, order parameter, entropy, heat capacity and compressibility to derive the critical properties of spin polarized nuclear matter. Our results indicate that for the spin polarized nuclear matter, the second order phase transition takes place at lower temperatures with respect to the unpolarized one. It is also shown that the critical temperature of our spin polarized nuclear matter with a specific value of spin polarization parameter is in good agreement with the experimental result.
Comments:
26 pages, 13 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1509.07903 [pdf]
IJMPE(2015)·6 citations
04
[Submitted on 26 Sept 2015]
Jets and Centrality in p(d)-A Collisions
M. Kordell🇺🇸 · A. Majumder🇺🇸
The production of jets, and high- $p_{T}$ leading pions from jets, in d-Au collisions at the Relativistic Heavy-Ion Collider (RHIC) and p-Pb collisions at the Large Hadron Collider (LHC) are studied. Using a modified version of the event generator PYTHIA, in conjunction with a nuclear Glauber Monte-Carlo event generator, we demonstrate how events with a hard jet may be simulated, in such a way that the parton distribution function of the projectile nucleon is frozen during its interaction with the extended nucleus. Using our hybrid Monte-Carlo event generator, we demonstrate that the enhancement in $R_{p A}$ seen in peripheral events at RHIC and at LHC, as well as the depletion in central or semi-central events, is mainly due to "mis-binning" of central and semi-central events with a jet, as peripheral events. This occurs due to the reduction of soft particle production caused by a depletion of energy available in a nucleon (of the deuteron in the case of d-Au collisions), after the production of a hard jet. This represents a form of "color transparency" of the projectile nucleon, which has fluctuated to a state with fewer and harder partons, in events which lead to jet production. We conclude with discussions of the form of multi-parton correlations in a nucleon which may be responsible for such a startling effect.
Comments:
4 pages, 6 figures, To be included in Hard Probes 2015 Proceedings
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.08011 [pdf]
Nucl.Part.Phys.Proc.(2016)·0 citations
05
[Submitted on 27 Sept 2015]
Nuclear excitations as coupled one and two random--phase--approximation modes
D. Gambacurta🇷🇴 · F. Catara🇮🇹 · M. Grasso🇫🇷 · M. Sambataro🇮🇹 · M. V. Andrés🇪🇸 · E. G. Lanza🇮🇹
We present an extension of the random--phase approximation (RPA) where the RPA phonons are used as building blocks to construct the excited states. In our model, that we call double RPA (DRPA), we include up to two RPA phonons. This is an approximate and simplified way, with respect to the full second random--phase approximation (SRPA), to extend the RPA by including two particle--two hole configurations. Some limitations of the standard SRPA model, related to the violation of the stability condition, are not encountered in the DRPA. We also verify in this work that the energy--weighted sum rules are satisfied. The DRPA is applied to low--energy modes and giant resonances in the nucleus $^{16}$ O. We show that the model (i) produces a global downwards shift of the energies with respect to the RPA spectra; (ii) provides a shift that is however strongly reduced compared to that generated by the standard SRPA. This model represents an alternative way of correcting for the SRPA anomalous energy shift, compared to a recently developed extension of the SRPA, where a subtraction procedure is applied. The DRPA provides results in good agreeement with the experimental energies, with the exception of those low--lying states that have a dominant two particle--two hole nature. For describing such states, higher--order calculations are needed.
Comments:
9 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1509.08078 [pdf]
PRC(2016)·14 citations
06
[Submitted on 27 Sept 2015]
QRPA treatment of the transverse wobbling mode reconsidered
S. Frauendorf · F. Doenau
The quasiparticle random phase approximation is used to study the properties of the wobbling bands in $^{163}$ Lu. Assuming that the wobbling mode represents pure isoscalar orientation oscillations results in too low wobbling frequencies and too strong M1 transitions between the one- and zero-phonon wobbling bands. The inclusion of an LL interaction, which couples the wobbling mode to the scissors mode, generates the right upshift of the wobbling frequencies and the right suppression of the B(M1) $_{o u t}$ values toward the experimental values. In analogy to the quenching of low-energy E1 transition by coupling to the Isovector Giant Dipole Resonance, a general reduction of the M1 transitions between quasiparticle configurations caused by coupling to the scissors mode is suggested.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08116 [pdf]
PRC(2015)·34 citations
07
[Submitted on 27 Sept 2015]
Emission of neutrino-antineutrino pairs by hadronic bremsstrahlung processes
Sonia Bacca · Rishi Sharma · Achim Schwenk
We review our recent calculations of neutrino-antineutrino pair production from bremsstrahlung processes in hadronic collisions at temperature and densities relevant for core-collapse supernovae. We focus on neutron-neutron and neutron-alpha collisions.
Comments:
8 pages, 4 figures, proceedings of the NN2015 conference, Catania, 21-26 June, 2015
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08151 [pdf]
EPJ Web Conf.(2016)·1 citation
08
[Submitted on 28 Sept 2015]
Heavy Vector and Axial-Vector Mesons in Hot and Dense Asymmetric Strange Hadronic Matter
Arvind Kumar · Rahul Chhabra
We calculate the effects of finite density and temperature of isospin asymmetric strange hadronic matter, for different strangeness fractions, on the in-medium properties of vector $(D^{*}, D_{s}^{*}, B^{*}, B_{s}^{*})$ and axial-vector $(D_{1}, D_{1 s}, B_{1}, B_{1 s})$ mesons, using chiral hadronic SU(3) model and QCD sum rules. We focus on the evaluation of in-medium mass-shift and shift in decay constant of above vector and axial-vector mesons. In QCD sum rule approach, the properties, e.g., the masses and decay constants of vector and axial-vector mesons are written in terms of quark and gluon condensates. These quark and gluon condensates are evaluated in the present work within chiral SU(3) model, through the medium modification of, scalar-isoscalar fields $σ$ and $ζ$ , the scalar-isovector field $δ$ and scalar dilaton field $χ$ , in the strange hadronic medium which includes both nucleons as well as hyperons. As we shall see in detail, the masses and decay constants of heavy vector and axial-vector mesons are affected significantly due to isospin asymmetry and strangeness fraction of the medium and these modifications may influence the experimental observables produced in heavy ion collision experiments. The results of present investigations of in-medium properties of vector and axial-vector mesons at finite density and temperature of strange hadronic medium may be helpful for understanding the experimental data from heavy-ion collision experiments in-particular for the Compressed Baryonic Matter (CBM) experiment of FAIR facility at GSI, Germany.
Comments:
36 pages and 9 figures. arXiv admin note: substantial text overlap with arXiv:1506.02115
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1509.08247 [pdf]
Physical Review C 92, 035208 (2015)
09
[Submitted on 28 Sept 2015]
Clustering in nuclei from ab initio nuclear lattice simulations
Ulf-G. Meißner🇩🇪
Nuclear Lattice Effective Field Theory is a new many-body approach that is firmly rooted in the symmetries of QCD. In particular, it allows for truly ab initio calculations of nuclear structure and reactions. In this talk, I focus on the emergence of alpha-clustering in nuclei based on this approach. I also discuss various recent achievements, the deficiencies of the chiral forces used at present and the prospects to improve upon these and the calculations of nuclear properties and dynamics.
Comments:
Contibution to "Chiral Dynamics 2015'', Pisa, Italy, June 29 to July 3, 2015
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08290 [pdf]
1 citation
10
[Submitted on 28 Sept 2015]
Dynamical description of heavy-ion collisions at Fermi energies
P. Napolitani🇫🇷 · M. Colonna🇮🇹
Descriptions of heavy-ion collisions at Fermi energies require to take into account in-medium dissipation and phase-space fluctuations. The interplay of these correlations with the one-body collective behaviour determines the properties (kinematics and fragment production) and the variety of mechanisms (from fusion to neck formation and multifragmentation) of the exit channel. Starting from fundamental concepts tested on nuclear matter, we build up a microscopic description which addresses finite systems and applies to experimental observables.
Comments:
12th International Conference on Nucleus-Nucleus Collisions (NN2015) 21-26 June 2015, Catania, Italy
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08293 [pdf]
EPJ Web Conf.(2016)·9 citations
11
[Submitted on 28 Sept 2015]
Peculiarities of quasifission reactions in heavy ion collisions
Avazbek Nasirov (1,2,3) · Bakhodir Kayumov (2,4) · Yongseok Oh (3,5,6) ((1) Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia, (2) Heavy Ion Physics Laboratory, Institute of Nuclear Physics, Tashkent, Uzbekistan, (3) Department of Physics, Kyungpook National University, Daegu, Republic of Korea, (4) Inha University in Tashkent, Uzbekistan, (5) Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk, Republic of Korea, (6) Institute for Nuclear Studies and Department of Physics, The George Washington University, Washington, USA)
The probability of the formation and decay of a dinuclear system is investigated for a wide range of relative orbital angular momentum values. The mass and angular distributions of the quasifission fragments are studied to understand the reaction mechanisms of the heavy ion collision of $^{78}$ Kr(10 $A$ MeV) + $^{40}$ Ca within dinuclear system model. The quasifission products are found to contribute to the mass-symmetric region of the mass distribution in collisions with a large orbital angular momentum. The analysis of mass and angular distributions of quasifission fragments shows the possibility of the $18 0^{\circ}$ rotation of the system so that projectile-like products can be observed in the forward hemisphere with large cross sections, which can explain the phenomenon observed recently in the ISODEC experiment.
Comments:
21 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08348 [pdf]
NPA(2016)·6 citations
12
[Submitted on 26 Sept 2015] (cross-list from hep-lat)
Perturbative results for two and three particle threshold energies in finite volume
Maxwell T. Hansen🇩🇪 · Stephen R. Sharpe🇺🇸
We calculate the energy of the state closest to threshold for two and three identical, spinless particles confined to a cubic spatial volume with periodic boundary conditions and with zero total momentum in the finite-volume frame. The calculation is performed in relativistic quantum field theory with particles coupled via a $λ ϕ^{4}$ interaction, and we work through order $λ^{3}$ . The energy shifts begin at $O (1/ L^{3})$ , and we keep subleading terms proportional to $1/ L^{4}$ , $1/ L^{5}$ and $1/ L^{6}$ . These terms allow a non-trivial check of the results obtained from quantization conditions that hold for arbitrary interactions, namely that of Lüscher for two particles and our recently developed formalism for three particles. We also compare to previously obtained results based on non-relativistic quantum mechanics.
Comments:
15 pages, 5 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1509.07929 [pdf]
PRD(2016)·71 citations
13
[Submitted on 26 Sept 2015] (cross-list from nucl-ex)
Novel Collective Phenomena in High-Energy Proton-Proton and Proton-Nucleus Collisions
Kevin Dusling🇺🇸 · Wei Li🇺🇸 · Bjoern Schenke🇺🇸
The observation of long-range collective correlations for particles emitted in high-multiplicity pp and pPb collisions has opened up new opportunities of investigating novel high-density QCD phenomena in small colliding systems. We review experimental results related to the studies of collective phenomena in small systems from RHIC and the LHC over the past several years. Latest development in theoretical interpretations motivated by different frameworks are also reviewed, and confronted with the experimental data. Perspectives on possible future directions are discussed, with the aim of further exploring the rich emergent QCD phenomena.
Comments:
77 pages, 43 figures, invited review in International Journal of Modern Physics E
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.07939 [pdf]
IJMPE(2016)·301 citations
14
[Submitted on 27 Sept 2015] (cross-list from hep-ph)
Role of the $f_{1} (1285)$ state in the $J / ψ \to ϕ K ˉ K^{*}$ and $J / ψ \to ϕ f_{1} (1285)$ decays
Ju-Jun Xie🇨🇳 · E. Oset🇨🇳
We study the role of the $f_{1} (1285)$ resonance in the decays of $J / ψ \to ϕ K ˉ K^{*}$ and $J / ψ \to ϕ f_{1} (1285)$ . The theoretical approach is based on the results of chiral unitary theory where the $f_{1} (1285)$ resonance is dynamically generated from the $K^{*} K ˉ - c . c .$ interaction. In order to further test the dynamical nature of the $f_{1} (1285)$ state, we investigate the $J / ψ \to ϕ K ˉ K^{*}$ decay close to the $K ˉ K^{*}$ threshold and make predictions for the ratio of the invariant mass distributions of the $J / ψ \to ϕ K ˉ K^{*}$ decay and the $J / ψ \to ϕ f_{1} (1285)$ partial decay width with all the parameters of the mechanism fixed in previous studies. The results can be tested in future experiments and therefore offer new clues on the nature of the $f_{1} (1285)$ state.
Comments:
5 pages, 3 figures; accepted by Phys. Lett. B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.08099 [pdf]
PLB(2016)·9 citations
15
[Submitted on 28 Sept 2015] (cross-list from hep-ph)
Holographic entropy and real-time dynamics of quarkonium dissociation in non-Abelian plasma
Ioannis Iatrakis🇺🇸 · Dmitri E. Kharzeev🇺🇸
The peak of the heavy quark pair entropy at the deconfinement transition, observed in lattice QCD, suggests that the transition is effectively driven by the increase of the entropy of bound states. The growth of the entropy with the inter-quark distance leads to the emergent entropic force that induces dissociation of quarkonium states. Since the quark-gluon plasma around the transition point is a strongly coupled system, we use the gauge-gravity duality to study the entropy of heavy quarkonium and the real-time dynamics of its dissociation. In particular, we employ the Improved Holographic QCD model as a dual description of large $N_{c}$ Yang Mills theory. Studying the dynamics of the fundamental string between the quarks placed on the boundary, we find that the entropy peaks at the transition point. We also study the real-time dynamics of the system by considering the holographic string falling in the black hole horizon where it equilibrates. In the vicinity the deconfinement transition, the dissociation time is found to be less than a fermi, suggesting that the entropic destruction is the dominant dissociation mechanism in this temperature region.
Comments:
7 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1509.08286 [pdf]
PRD(2016)·32 citations
16
[Submitted on 28 Sept 2015] (cross-list from hep-ph)
Self-similarity of strangeness production in pp collisions at RHIC
M. Tokarev (1) · I. Zborovsky (2) ((1) Veksler and Baldin Laboratory of High Energy Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, Russia (2) Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, Czech Republic)
New experimental data on transverse momentum spectra of strange particles (KS0, K-, K*, phi,...) produced in pp collisions at sqrt s = 200 GeV obtained by the STAR and PHENIX collaborations at RHIC are analysed in the framework of z-scaling approach. Scaling properties of the data z-presentation are illustrated. Self-similarity of strange particle production is discussed. A microscopic scenario of constituent interactions developed within the z-scaling approach is used to study constituent energy loss, proton momentum fraction and recoil mass in dependence on the transverse momentum, strangeness, and mass of the inclusive particle. The obtained results can be useful for understanding strangeness origin, for searching for new physics with strange probes and can serve as a benchmark for complex analyses of self-similar features of strange production in heavy ion collisions.
Comments:
4 pages, LaTeX, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.08426 [pdf]
J.Phys.Conf.Ser.(2016)·4 citations
17
[Submitted on 28 Sept 2015] (cross-list from hep-ph)
A covariant model for the negative parity resonances of the nucleon
G. Ramalho🇧🇷
We present a model for the $γ^{*} N \to N^{*}$ helicity amplitudes, where $N$ is the nucleon and $N^{*}$ is a negative parity nucleon excitation, member of the $S U (6)$ -multiplet $[70, 1^{-}]$ . The model combines the results from the single quark transition model for the helicity amplitudes with the results of the covariant spectator quark model for the $γ^{*} N \to N^{*} (1535)$ and $γ^{*} N \to N^{*} (1520)$ transitions. With the knowledge of the amplitudes $A_{1/2}$ and $A_{3/2}$ for those transitions we calculate three independent coefficients defined by the single quark transition model and make predictions for the helicity amplitudes associated with the $γ^{*} N \to N^{*} (1650)$ , $γ^{*} N \to N^{*} (1700)$ , $γ^{*} N \to Δ (1620)$ , and $γ^{*} N \to Δ (1700)$ transitions. In order to facilitate the comparison with future experimental data at high $Q^{2}$ , we provide also simple parametrizations for the amplitudes, compatible with the expected falloff at high $Q^{2}$ .
Comments:
Proceedings of the workshop "XIII International Workshop on Hadron Physics", 22-27 March 2015, Hotel do Bosque, Angra dos Reis - RJ, Brazil. 8 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.08436 [pdf]
J.Phys.Conf.Ser.(2016)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE