Nuclear Theory·nucl-th

Wednesday·January 30, 2019

12 papers—7 primary·5 cross-listed

01
[Submitted on 29 Jan 2019]
Theory of surrogate nuclear and atomic reactions with three charged particles in the final state proceeding through a resonance in the intermediate subsystem
A. M. Mukhamedzhanov · A. S. Kadyrov
Within a few-body formalism, we develop a general theory of surrogate nuclear and atomic reactions with the excitation of a resonance in the intermediate binary subsystem leading to three charged particles in the final state. The Coulomb interactions between the spectator and the resonance in the intermediate state and between the three particles in the final state are taken into account. Final-state three-body Coulomb multiple-scattering effects are accounted for using the formalism of the three-body Coulomb asymptotic states based on the work published by one of us (A.M.M.) under the guidance of L. D. Faddeev. An expression is derived for the triply differential cross section. It can be used for investigation of the Coulomb effects on the resonance line shape as well as the energy dependence of the cross section. We find that simultaneous inclusion of the Coulomb effects in the intermediate and final state decreases the effect of the final-state Coulomb interactions on the triply differential cross section.
Comments:
Submitted to a special issue of the journal Few-Body Systems dedicated to Prof. Ludwig Faddeev
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.10083 [pdf]
Few Body Syst.(2019)·5 citations
02
[Submitted on 29 Jan 2019]
Rapidity Decorrelation from Hydrodynamic Fluctuations and Initial Fluctuations
Azumi Sakai🇯🇵 · Koichi Murase🇯🇵 · Tetsufumi Hirano🇯🇵
Rapidity decorrelation in high energy heavy-ion collisions is one of the hot topics in understanding longitudinal dynamics of the quark gluon plasma (QGP). In this study we employ an integrated dynamical model with full three dimensional relativistic hydrodynamics and perform event-by-event numerical simulations of Pb+Pb collisions at the LHC energy. We analyze factorization ratios to understand rapidity decorrelation from hydrodynamic fluctuations and initial longitudinal fluctuations. We show that factorization breaking happens due to both hydrodynamic fluctuations and initial longitudinal fluctuations. We conclude hydrodynamic fluctuations and initial longitudinal fluctuations are both important in understanding rapidity decorrelation.
Comments:
4 pages, 3 figures; contribution to the proceedings of the 8th International Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba, November 13-17, 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.10120 [pdf]
JPS Conf.Proc.(2019)·1 citation
03
[Submitted on 29 Jan 2019]
Weak production of strange and charm ground-state baryons in nuclei
J. E. Sobczyk🇪🇸 · N. Rocco🇺🇸 · A. Lovato🇺🇸 · J. Nieves🇪🇸
We present results for the quasi-elastic weak production of $Λ$ and $Σ$ hyperons induced by $ν ˉ$ scattering off nuclei, in the kinematical region of interest for accelerator neutrino experiments. We employ realistic hole spectral functions and we describe the propagation of the hyperons in the nuclear medium by means of a Monte Carlo cascade. The latter strongly modifies the kinematics and the relative production rates of the hyperons, leading to a non-vanishing $Σ^{+}$ cross section, to a sizable enhancement of the $Λ$ production and to a drastic reduction of the $Σ^{0}$ and $Σ^{-}$ distributions. We also compute the quasi-elastic weak $Λ_{c}$ production cross section, paying special attention to estimate the uncertainties induced by the model dependence of the vacuum $n \to Λ_{c}$ weak matrix element. In this regard, the recent BESIII measurements of the branching ratios of $Λ_{c} \to Λ l^{+} ν_{l}$ ( $l = e, μ$ ) are used to benchmark the available theoretical predictions.
Comments:
18 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1901.10192 [pdf]
PRC(2019)·15 citations
04
[Submitted on 29 Jan 2019]
What could be learned about phase transitions, meson and nucleon structure in hot medium from a chiral quark-meson theory?
Christo V. Christov🇩🇪
In this contribution I summarize and discuss the results of the bulk thermodynamic characteristics, meson and nucleon structure in hot matter obtained in the framework of a chiral quark-meson theory. A hybrid NJL model is used in which a Dirac sea of quarks is combined with a Fermi sea of quarks or of nucleons. In the model mesons are described as collective $q ˉ q$ excitations and the nucleon appears as a baryon-number-one soliton of $N_{c}$ valence quarks coupled to both Dirac and Fermi sea. According to the model at some critical density and/or temperature phase transitions from nucleons to quarks as well as from Goldstone to Wigner phase are expected. At finite density the chiral order parameter and the constituent quark mass have a non-monotonic temperature dependence-at temperatures not close to the critical one they are less affected than in cold matter. The quark matter is rather soft against thermal fluctuations and the corresponding chiral phase transition is smooth. The nucleon matter is much stiffer and the phase transition is very sharp. In the case of quark matter a first-order transition is suggested at low temperatures ( $T < 80$ MeV) which changes to a second-order one at higher temperatures. In contrast to the quark matter in the case of nucleon matter the thermodynamic variables show large discontinuities which is a clear indication for a first-order phase transition. In hot medium at intermediate temperature the nucleon soliton is more bound and less swelled than in the case of cold matter. At some critical temperature, which for nucleon matter coincides with the critical temperature for the phase transition, no more a localized solution is found. According to this model scenario one should expect a first-order phase transition from nucleon to quark matter.
Comments:
15 pages, 11 figures, in Proceedings of the 37th International Workshop on Nuclear Theory, 24-30 June 2018, Borovetz, Bulgaria
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.10282 [pdf]
0 citations
05
[Submitted on 29 Jan 2019]
Propagation of Statistical Uncertainties of Skyrme Mass Models to Simulations of $r$ -Process Nucleosynthesis
T. M. Sprouse · R. Navarro Perez · R. Surman · M. R. Mumpower · G. C. McLaughlin · N. Schunck
Uncertainties in nuclear models have a major impact on simulations that aim at understanding the origin of heavy elements in the universe through the rapid neutron capture process ( $r$ process) of nucleosynthesis. Within the framework of the nuclear density functional theory, we use results of Bayesian statistical analysis to propagate uncertainties in the parameters of energy density functionals to the predicted $r$ -process abundance pattern, by way not only of the nuclear masses but also through the influence of the masses on $β$ -decay and neutron capture rates. We additionally make the first identifications of specific parameters of Skyrme-like energy density functionals which are correlated with particular aspects of the $r$ -process abundance pattern. While previous studies have explored the reduction in the abundance pattern uncertainties due to anticipated new measurements of neutron-rich nuclei, here we point out that an even larger reduction will occur when these new measurements are used to reduce the uncertainty of model predictions of masses, which are then propagated through to the abundance pattern. We make a quantitative prediction for how large this reduction will be.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.10337 [pdf]
PRC(2020)·51 citations
06
[Submitted on 29 Jan 2019]
Examination of an isospin-dependent single-nucleon momentum distribution for the isospin-asymmetric nuclear matter in heavy-ion collisions
Gao-Feng Wei🇨🇳 · Qi-Jun Zhi🇨🇳 · Xin-Wei Cao🇨🇳 · Zheng-Wen Long🇨🇳
Within a transport model using as the input nucleon momentum profiles from a parameterized isospin-dependent single-nucleon momentum distribution with a high momentum tail induced by short-range correlations, we employ the $^{197}$ Au + $^{197}$ Au collisions at 400 MeV/nucleon to examine on one hand effects of the short-range correlations on the pion and flow observables in probing the nuclear symmetry energy, and on the other hand how reliable are this isospin-dependent single-nucleon momentum distribution as well as the corresponding parameter settings. Besides significant effects of the short-range correlations on the pion and flow observables are observed, we also find that the theoretical simulations of $^{197}$ Au + $^{197}$ Au collisions with this momentum distribution using two sets of parameters extracted from the experimental analysis and the self-consistent Green's function prediction, respectively, can reproduce the neutron elliptic flows of the FOPI-LAND experiment and the $π^{-} / π^{+}$ ratios of the FOPI experiment under the symmetry energy setting in a certain range. Therefore, we conclude that this parameterized isospin-dependent single-nucleon momentum distribution is reliable for the isospin-asymmetric nuclear matter, correspondingly, two sets of parameters extracted from both the experimental analysis and the self-consistent Green's function prediction can not be ruled out according to the available experimental information at present.
Comments:
10 pages, and 9 figures, published version to meet the journal's style
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1901.10391 [pdf]
Nucl.Sci.Tech.(2020)·12 citations
07
[Submitted on 29 Jan 2019]
Comment on "How (not) to renormalize integral equations with singular potentials in effective field theory"
Manuel Pavon Valderrama🇨🇳
I critically discuss two of the potential inconsistencies pointed out in the recent manuscript by Epelbaum, Gasparyan, Gegelia and Meissner, published in Eur. Phys.J. A54, 186 (2018). The potential inconsistencies are: (i) a possible mismatch between the $ℏ$ expansion of the scattering amplitude and renormalization, (ii) an impossibility of "non-perturbative renormalization" to deal with repulsive singular interactions. The conclusion is that these inconsistencies do not happen.
Comments:
3 pages, one figure, comment on Eur. Phys.J. A54, 186 (2018). It corresponds to the accepted version in EPJA (except for the abstract, which EPJA comments do not have)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1901.10398 [pdf]
EPJA(2019)·19 citations
08
[Submitted on 28 Jan 2019] (cross-list from hep-ph)
Charmonium Excitation functions in $p ˉ$ A Collisions
Gy. Wolf🇭🇺 · G. Balassa🇭🇺 · P. Kovacs🇭🇺 · M. Zetenyi🇭🇺 · S.H. Lee🇰🇷
We study the excitation function of the low-lying charmonium state: $Ψ$ (3686) in $p ˉ$ Au collisions taking into account their in-medium propagation. The time evolution of the spectral functions of the charmonium state is studied with a BUU type transport model. We calculated the excitation function of $Ψ$ (3686) production and show that it is strongly effected by the medium. The energy regime will be available for the PANDA experiment.
Comments:
6 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:1712.06537
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.09910 [pdf]
Acta Phys.Polon.Supp.(2018)·4 citations
09
[Submitted on 28 Jan 2019] (cross-list from nucl-ex)
Probing nucleon's spin structures with polarized Drell-Yan in the Fermilab SpinQuest experiment
Andrew Chen🇺🇸 · J.C. Peng🇺🇸 · H. Leung🇺🇸 · M. Tian🇺🇸 · N. Makins🇺🇸 · M. Brooks🇺🇸 · A. Klein🇺🇸 · D. Kleinjan🇺🇸 · K. Liu🇺🇸 · M. McCumber🇺🇸 · P. McGaughey🇺🇸 · J. Miraal-Martinez🇺🇸 and 42 other authors
Although the proton was discovered about 100 years ago, its spin structure still remains a mystery. Recent studies suggest that the orbital angular momentum of sea quarks could significantly contribute to the proton's spin. The SeaQuest experiment, which recently completed data collection, probed the unpolarized light quark sea distributions of the proton using the Drell-Yan process. Its successor, the SpinQuest (E1039), will access the $u ˉ$ and $d ˉ$ Sivers functions using polarized NH $_{3}$ and ND $_{3}$ targets. A non-zero Sivers asymmetry, observed in SpinQuest, would be a strong indication of non-zero sea-quark orbital angular momentum. The SpinQuest experiment can also probe the sea quark's transversity distribution, which is relevant for the determination of proton's tensor charge. Recent study suggests that sea-quarks might contribute significantly to deuteron's tensor polarized structure functions. This can be further probed in SpinQuest using tensor polarized ND $_{3}$ target. The current status and future plan of the experiment are presented.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1901.09994 [pdf]
PoS(2019)·22 citations
10
[Submitted on 29 Jan 2019] (cross-list from hep-lat)
Meson deformation by magnetic fields in lattice QCD
Koichi Hattori🇯🇵 · Arata Yamamoto🇯🇵
We study light meson properties in a magnetic field, focusing on a charged pion and a charged and polarized rho meson, in quenched lattice QCD. The gauge-invariant density-density correlators are calculated to investigate the deformation caused by the magnetic field. We find that these mesons acquire elongated shapes along the magnetic field. The magnitude of the deformation is about 10-20 % when the strength of the magnetic field is of the order of the squared unphysical pion mass.
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.10182 [pdf]
PTEP(2019)·16 citations
11
[Submitted on 29 Jan 2019] (cross-list from hep-ph)
Spin partners $W_{b J}$ from the line shapes of the $Z_{b} (10610)$ and $Z_{b} (10650)$
V. Baru🇩🇪 · E. Epelbaum🇩🇪 · A. A. Filin🇩🇪 · C. Hanhart🇩🇪 · A. V. Nefediev🇷🇺 · Q. Wang🇩🇪
In a recent paper Phys.Rev. D98, 074023 (2018), the most up-to-date experimental data for all measured production and decay channels of the bottomonium-like states $Z_{b} (10610)$ and $Z_{b} (10650)$ were analysed in a field-theoretical coupled-channel approach which respects analyticity and unitarity and incorporates both the pion exchange as well as a short-ranged potential nonperturbatively. All parameters of the interaction were fixed directly from data, and pole positions for both $Z_{b}$ states were determined. In this work we employ the same approach to predict in a parameter-free way the pole positions and the line shapes in the elastic and inelastic channels of the (still to be discovered) spin partners of the $Z_{b}$ states. They are conventionally referred to as $W_{b J}$ 's with the quantum numbers $J^{P C} = J^{++}$ ( $J = 0, 1, 2$ ). It is demonstrated that the results of our most advanced pionful fit, which gives the best $χ^{2} / d.o.f.$ for the data in the $Z_{b}$ channels, are consistent with all $W_{b J}$ states being above-threshold resonances which manifest themselves as well pronounced hump structures in the line shapes. On the contrary, in the pionless approach, all $W_{b J}$ 's are virtual states which can be seen as enhanced threshold cusps in the inelastic line shapes. Since the two above scenarios provide different imprints on the observables, the role of the one-pion exchange in the $B^{(*)} B ˉ^{(*)}$ systems can be inferred from the once available experimental data directly.
Comments:
24 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1901.10319 [pdf]
PRD(2019)·54 citations
12
[Submitted on 29 Jan 2019] (cross-list from hep-ph)
On the elliptic flow of heavy quarkonia in $p A$ collisions
Cheng Zhang🇨🇳 · Cyrille Marquet🇫🇷 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇫🇷 · Bo-Wen Xiao🇨🇳
Using the dilute-dense factorization in the Color Glass Condensate framework, we investigate the azimuthal angular correlation between a heavy quarkonium and a charged light hadron in proton-nucleus collisions. We extract the second harmonic $v_{2}$ , commonly known as the elliptic flow, with the light hadron as the reference. This particular azimuthal angular correlation between a heavy meson and a light hadron has first been measured at the LHC recently. The experimental results indicate that the elliptic flows for heavy-flavor mesons ( $J / ψ$ and $D^{0}$ ) are almost as large as those for light hadrons. Our calculation demonstrates that this result can be naturally interpreted as an initial state effect due to the interaction between the incoming partons from the proton and the dense gluons inside the target nucleus. Since the heavy quarkonium $v_{2}$ exhibits a weak mass dependence according to our calculation, we predict that the heavy quarkonium $Υ$ should have a similar elliptic flow as compared to that of the $J / ψ$ , which can be tested in future measurements.
Comments:
6 pages, 3 figures;v2: a few minor typo corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1901.10320 [pdf]
PRL(2019)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE