Nuclear Theory·nucl-th

Thursday·March 7, 2019

14 papers—8 primary·6 cross-listed

01
[Submitted on 5 Mar 2019]
Odd-mass nuclei in the cluster shell model
R. Bijker · A.H. Santana-Valdés
In this contribution, we present the cluster shell model which is analogous to the Nilsson model, but for cluster potentials. Special attention is paid to the consequences of the discrete symmetries of three alpha-particles in an equilateral triangle configuration. This configuration is characterized by a special structure of the rotational bands which can be used as a fingerprint of the underlying geometric configuration. The cluster shell model is applied to the nucleus 13C.
Comments:
9 pages, 6 figures, 4 tables, invited talk at XLII Symposium on Nuclear Physics, Cocoyoc, Mexico, January 7-10, 2019. To be published in Journal of Physics Conference Series
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1903.02068 [pdf]
J.Phys.Conf.Ser.(2019)·2 citations
02
[Submitted on 5 Mar 2019]
Electromagnetic couplings of pentaquarks
E. Ortiz-Pacheco🇲🇽 · R. Bijker🇲🇽
In this contribution, we discuss the electromagnetic couplings of pentaquark states with hidden charm. This work is motivated by recent experiments at CERN by the LHCb Collaboraton and current experiments at JLab to confirm the existence of hidden-charm pentaquarks in photoproduction experiments.
Comments:
5 pages, 2 figures, 1 table, XLII Symposium on Nuclear Physics, Cocoyoc, Mexico, January 7-10, 2019. To be published in Journal of Physics Conference Series
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1903.02070 [pdf]
J.Phys.Conf.Ser.(2019)·0 citations
03
[Submitted on 6 Mar 2019]
The symmetry energy of the nuclear EoS: a study of collective motion and low-energy reaction dynamics in semiclassical approaches
Stefano Burrello · Maria Colonna · Hua Zheng
In the framework of mean-field based transport approaches, we discuss recent results concerning collective motion and low-energy heavy ion reactions involving neutron-rich systems. We focus on aspects which are particularly sensitive to the isovector terms of the nuclear effective interaction and the corresponding symmetry energy. As far as collective excitations are concerned, we discuss the mixed nature of dipole oscillations in neutron-rich systems. On the other hand, for reactions close to the Coulomb barrier, we investigate the structure of pre-equilibrium collective dipole oscillations, focusing on their sensitivity to the symmetry energy behavior below normal density. Nucleon emission is also considered within the same context. The possible impact of other relevant terms of the nuclear effective interaction on these mechanisms is also examined. From this analysis we expect to put further constraints on the nuclear Equation of State, of crucial importance also in the astrophysical context.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02266 [pdf]
Front.in Phys.(2019)·15 citations
04
[Submitted on 6 Mar 2019]
Photoproduction of $K^{+} Λ$ with a Regge-plus-resonance model
Petr Bydžovský🇨🇿 · Dalibor Skoupil🇨🇿
Making use of the hybrid Regge-plus-resonance model, we investigate the process of kaon photoproduction off the proton target. We present a new model whose free parameters were adjusted to data in and above the resonance region and which provides an acceptable description of experimental data. The overwhelming majority of nucleon resonances selected in this analysis overlaps with those selected in our previous analyses and also with the Bayesian analysis with the Regge-plus-resonance model, which we deem to be dependable. A novel feature of our model consists in applying a different scheme for gauge-invariance restoration, which results in a need for implementing a contact current. As we further reveal, the choice of the gauge invariance restoration scheme as well as the choice of either pseudoscalar or pseudovector coupling in the strong vertex play a significant role for cross-section predictions at forward angles where data are scarce.
Comments:
20 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02292 [pdf]
PRC(2019)·13 citations
05
[Submitted on 6 Mar 2019]
Volume fluctuation and multiplicity correlation on higher-order cumulants
Tetsuro Sugiura🇯🇵 · Toshihiro Nonaka🇨🇳 · ShinIchi Esumi🇯🇵
Initial volume fluctuation (VF) arising from the participant fluctuation would be the background which should be subtracted experimentally from the measured higher-order cumulants. We study the validity of the Volume Fluctuation Correction (VFC) on higher-order net-proton cumulants by using simple toy model and UrQMD model in Au+Au collisions at \sqrt s_{NN} = 200 GeV for various centrality definitions. The results are compared to the conventional data driven method called Centrality Bin Width Correction (CBWC). We find VFC works well in toy model assuming independent particle production (IPP), but does not seem to work well in UrQMD model. It is also found that cumulants are strongly affected by the multiplicity correlation effect as well as the centrality resolution effect. These results show that neither VFC nor CBWC are perfect method. Thus, both methods should be compared in the real experiment.
Comments:
8 pages and 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1903.02314 [pdf]
PRC(2019)·25 citations
06
[Submitted on 6 Mar 2019]
Effects of quantum statistics near the critical point of nuclear matter
S.N. Fedotkin · A.G. Magner · M.I. Gorenstein
Effects of quantum statistics for nuclear matter equation of state are analyzed in terms of the recently proposed quantum van der Waals model. The system pressure is expanded over a small parameter $δ \propto n (m T)^{- 3/2} [g (1 - bn)]^{- 1}$ , where $n$ and $T$ are, respectively, the particle number density and temperature, $m$ and $g$ the particle mass and degeneracy factor. The parameter $b$ corresponds to the van der Waals excluded volume. The corrections due to quantum statistics for the critical point values of $T_{c}$ , $n_{c}$ , and the critical pressure $P_{c}$ are found within the linear and quadratic orders over $δ$ . These approximate analytical results appear to be in a good agreement with exact numerical calculations in the quantum van der Waals model for interacting Fermi particles: the symmetric nuclear matter ( $g = 4$ ) and the pure neutron matter ( $g = 2$ ). They can be also applied to the system of interacting Bose particles like the matter composed of $α$ nuclei.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02361 [pdf]
PRC(2019)·8 citations
07
[Submitted on 5 Mar 2019]
Influence of orthogonalization procedure on astrophysical S-factor for the direct $α + d$ $\to$ $^{6}$ Li + $γ$ capture process in a three-body model
E.M. Tursunov · A.S. Kadyrov
The astrophysical S-factor for the direct $α (d, γ)^{6} Li$ capture reaction is calculated in a three-body model based on the hyperspherical Lagrange-mesh method. A sensitivity of the E1 and E2 astrophysical S-factors to the orthogonalization method of Pauli forbidden states in the three-body system is studied. It is found that the method of orthogonalising pseudopotentials (OPP) yields larger isotriplet ( $T = 1$ ) components than the supersymmetric transformation (SUSY) procedure. The E1 astrophysical S-factor shows the same energy dependence in both cases, but strongly different absolute values. At the same time, the E2 S-factor does not depend on the orthogonalization procedure. As a result, the OPP method yields a very good description of the direct data of the LUNA collaboration at low energies, while the SUSY transformation strongly underestimates the LUNA data. \keywords{three-body model; orthogonalization method; astrophysical S factor.
Comments:
8 pages, 3 figures. arXiv admin note: text overlap with arXiv:1808.04125
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02403 [pdf]
Int.J.Mod.Phys.Conf.Ser.(2019)·1 citation
08
[Submitted on 6 Mar 2019]
A statistical analysis of the nuclear structure uncertainties in $μ$ D
Oscar J. Hernandez🇩🇪 · Sonia Bacca🇩🇪 · Nir Barnea🇮🇱 · Nir Nevo-Dinur🇨🇦 · Andreas Ekström🇸🇪 · Chen Ji🇨🇳
The charge radius of the deuteron (D), was recently determined to three times the precision compared with previous measurements using the measured Lamb shift in muonic deuterium (muD). However, the muD value is 5.6 $σ$ smaller than the world averaged CODATA-2014 value [1]. To shed light on this discrepancy we analyze the uncertainties of the nuclear structure calculations of the Lamb shift in muD and conclude that nuclear theory uncertainty is not likely to be the source of the discrepancy.
Comments:
4 pages, 1 figure, accepted proceedings of the "XXII International Conference on Few-Body Problems in Physics", 9-13 July 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.02451 [pdf]
Springer Proc.Phys.(2020)·1 citation
09
[Submitted on 5 Mar 2019] (cross-list from hep-ph)
Factorization of jet cross sections in heavy-ion collisions
Jian-Wei Qiu🇺🇸 · Felix Ringer🇺🇸 · Nobuo Sato🇺🇸 · Pia Zurita🇩🇪
We propose a new phenomenological approach to establish QCD factorization of jet cross sections in the heavy-ion environment. Starting from a factorization formalism in proton-proton collisions, we introduce medium modified jet functions to capture the leading interaction of jets with the hot and dense QCD medium. A global analysis using a Monte Carlo sampling approach is performed in order to reliably determine the new jet functions from the nuclear modification factor of inclusive jets at the LHC. We find that gluon jets are significantly more suppressed due to the presence of the medium than quark jets. In addition, we observe that the jet radius dependence is directly related to the relative suppression of quark and gluon jets. Our approach may help to improve the extraction of medium properties from data.
Comments:
6 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1903.01993 [pdf]
PRL(2019)·65 citations
10
[Submitted on 6 Mar 2019] (cross-list from hep-th)
A semi-classical transport equation for the chiral quarks surrounding a SU(2) t'Hooft-Polyakov monopole
Feng Li🇩🇪
A transport equation of the representative quasi-particles is derived, by solving Dirac (or Dyson) equations under the semi-classical approximation, for describing the entangled motions of the red and blue chiral quarks in the vicinity of a SU(2) t'Hooft-Polyakov monopole. The representative quasi-particles have two states characterized by different dispersion relations. A ground state quasi-particle has a zero pole mass, a zero longitudinal inertial mass and a finite transverse inertial mass, while an excited quasi-particle has a finite pole mass and finite inertial masses. At equilibrium, the red and blue currents flow against each other in the transverse direction, and the red and blue axial currents flow against each other in the radial direction.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1903.02198 [pdf]
0 citations
11
[Submitted on 6 Mar 2019] (cross-list from hep-ph)
Bayesian techniques and applications to QCD
Alexander Rothkopf🇳🇴
Realizing the full potential of interconnecting the large amounts of data created in physics experiments, phenomenological models and theory simulations requires robust tools for statistical inference. Here I review a particularly promising branch, Bayesian statistics, which over the past decade has found manifold use in high-energy physics. After a brief introduction to Bayesian statistics I will present two concrete examples, where Bayesian thinking has led to progress in understanding strongly interacting matter: unfolding problems in the form of lattice QCD spectral functions (in spirit similar to detector corrections), as well as the efficient estimation of quark-gluon-plasma parameters from a systematic comparison of experimental heavy-ion collision data and phenomenological models.
Comments:
12 pages, 4 figures, talk given at the XIIIth Quark Confinement and the Hadron Spectrum Conference 2018, Maynooth, Ireland
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Data Analysis, Statistics and Probability (physics.data-an)
arXiv:
1903.02293 [pdf]
PoS(2018)·12 citations
12
[Submitted on 6 Mar 2019] (cross-list from hep-lat)
In-medium heavy quarkonium from lattice NRQCD
Seyong Kim🇰🇷 · Peter Petreczky🇺🇸 · Alexander Rothkopf🇳🇴
We present the final results from a multi-year study of the in-medium spectral properties of heavy quarkonium bound states on the lattice. In this work we combine high statistics $N_{f} = 2 + 1$ ensembles from the HotQCD collaboration with the effective theory NRQCD and improved Bayesian spectral reconstruction methods. We corroborate with high precision the hierarchical in-medium modification of quarkonium states with respect to their vacuum binding energy and provide updated values on melting temperatures. In particular we are able to understand previous disagreements between different Bayesian methods as resulting from underestimated systematic uncertainties. The main quantitative result is a robust determination of the in-medium mass shifts of quarkonium ground states, which we find are negative, consistent with the behavior observed in strongly coupled pNRQCD potential based computations.
Comments:
7 pages, 9 figures, talk given at the XIIIth Quark Confinement and the Hadron Spectrum Conference 2018, Maynooth, Ireland
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.02297 [pdf]
PoS(2019)·0 citations
13
[Submitted on 6 Mar 2019] (cross-list from hep-ph)
Hadron tomography for pion and its gravitational form factors
Qin-Tao Song🇯🇵
Generalized parton distributions (GPDs) are three-dimensional structure functions of hadrons, and they can reveal the orbital-angular-momentum contributions to the nucleon spin. Therefore, GPDs are important for solving the proton spin puzzle. The generalized distribution amplitudes (GDAs) are the $s$ - $t$ crossed quantities of the GPDs, and the GDAs can be investigated in two-photon process ( $γ^{*} γ \to h h ˉ$ ) which is accessible at KEKB. The pion GDAs were obtained by analyzing the Belle measurements for $π^{0} π^{0}$ production in the $e^{+} e^{-}$ collision. From the obtained GDAs, the form factors of energy-momentum tenor were calculated for pion in the timelike region. In order to study the gravitational radii for the pion, the form factors of energy-momentum tenor were obtained in the spacelike region by using the dispersion relation. Then, the mass radius was calculated as 0.32 $\sim$ 0.39 fm and the mechanical radius was also estimated for the pion as 0.82 $\sim$ 0.88 fm by using the spacelike form factors. This is the first finding on gravitational form factors and radii of hadrons from actual experimental measurements. In the near future we can expect more precise measurements of $γ^{*} γ \to h h ˉ$ as the Belle II started data taking by the higher luminosity Super KEKB, so that the GDAs of other hadrons could be studied as well.
Comments:
4 pages, 4 figures, Proceedings of Eighth International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1903.02298 [pdf]
JPS Conf.Proc.(2019)·1 citation
14
[Submitted on 6 Mar 2019] (cross-list from astro-ph.HE)
Monitoring of the eclipsing Wolf-Rayet ULX in the Circinus galaxy
Yanli Qiu · Roberto Soria
We studied the eclipsing ultraluminous X-ray source CG X-1 in the Circinus galaxy, re-examining two decades of {\it Chandra} and {\it XMM-Newton} observations. The short binary period (7.21 hr) and high luminosity ( $L_{X} \approx 1 0^{40}$ erg s $^{- 1}$ ) suggest a Wolf-Rayet donor, close to filling its Roche lobe; this is the most luminous Wolf-Rayet X-ray binary known to-date, and a potential progenitor of a gravitational-wave merger. We phase-connect all observations, and show an intriguing dipping pattern in the X-ray lightcurve, variable from orbit to orbit. We interpret the dips as partial occultation of the X-ray emitting region by fast-moving clumps of Compton-thick gas. We suggest that the occulting clouds are fragments of the dense shell swept-up by a bow shock ahead of the compact object, as it orbits in the wind of the more massive donor.
Comments:
10 pages, 4 figures. This manuscript is a slightly expanded and updated version of our contribution to the Proceedings of IAU Symposium 346, "High Mass X-ray Binaries: illuminating the passage from massive binaries to merging compact objects" (Vienna, August 2018)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1903.02327 [pdf]
IAU Symp.(2018)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE