Nuclear Theory·nucl-th

Wednesday·March 3, 2021

13 papers—6 primary·7 cross-listed

01
[Submitted on 1 Mar 2021]
Exploring Origins for Correlations between Flow Harmonics and Transverse Momentum in Small Collision Systems (Unambiguous Ambiguity)
S.H. Lim🇰🇷 · J.L. Nagle🇺🇸
High statistics data sets from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $ρ (v_{n}^{2}, [p_{T}])$ gauges the correlation between the mean transverse momentum of particles in an event and the various flow coefficients ( $v_{n}$ ) in the same event [1]. Recently it has been proposed that very low multiplicity events may be sensitive to initial-state glasma correlations [2] rather than flow-related dynamics. We find utilizing the IP-JAZMA framework that the color domain explanation for the glasma results are incomplete. We then explore predictions from PYTHIA-8, and the version for including nuclear collisions called PYTHIA-ANGANTYR, which have only non-flow correlations and the AMPT model which has both non-flow and flow-type correlations. We find that PYTHIA-ANGANTYR has non-flow contributions to $ρ (v_{n}^{2}, [p_{T}])$ in p+O, p+Pb, O+O collisions that are positive at low multiplicity and comparable to the glasma correlations. It is striking that in PYTHIA-8 in p+p collisions there is actually a sign-change from positive to negative $ρ (v_{n}^{2}, [p_{T}])$ as a function of multiplicity. The AMPT results match the experimental data general trends in Pb+Pb collisions at the LHC, except at low multiplicity where AMPT has the opposite sign. In p+Pb collisions, AMPT has the opposite sign from experimental data and we explore this within the context of parton geometry. Predictions for p+O, O+O, and Xe+Xe are also presented.
Comments:
15 pages, 17 figures, submitted for publication
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2103.01348 [pdf]
PRC(2021)·22 citations
02
[Submitted on 2 Mar 2021]
Unbound spectra of neutron-rich oxygen isotopes predicted by the Gamow shell model
J. G. Li🇨🇳 · N. Michel🇨🇳 · W. Zuo🇨🇳 · F. R. Xu🇨🇳
The Gamow shell model has shown to efficiently describe weakly bound and unbound nuclear systems, as internucleon correlations and continuum coupling are both taken into account in this model. In the present work, we study neutron-dripline oxygen isotopes. It is hereby demonstrated that the presence of continuum coupling is important for the description of oxygen isotopes at dripline, and especially to assess the eventual bound or unbound character of $^{28}$ O. Our results suggest that the ground state of $^{28}$ O is weakly unbound and is similar to the narrow resonant $^{26}$ O ground state. Predictions of weakly bound and resonance excited states in $^{24 - 26}$ O are also provided. The asymptotes of the studied many-body states are analyzed via one-body densities, whereby the different radial properties of well bound, loosely bound, resonance states are clearly depicted.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2103.01478 [pdf]
PRC(2021)·35 citations
03
[Submitted on 2 Mar 2021]
A Relativistic Quantum Approach to Neutrino and Antineutrino Emissions via the Direct Urca Process in Strongly Magnetized Neutron-Star Matter
Tomoyuki Maruyama🇯🇵 · A. Baha Balantekind🇺🇸 · Myung-Ki Cheoung🇰🇷 · Toshitaka Kajino🇯🇵 · Motohiko Kusakabef🇨🇳 · Grant J. Mathewsh🇺🇸
We study neutrino and antineutrino emission from the direct Urca process in neutron-star matter in the presence of strong magnetic fields. We calculate the neutrino emissivity of the direct Urca process, whereby a neutron converts to a proton, an electron and an antineutrino, or a proton-electron pair converts to a neutron-neutrino pair. We solve exact wave functions for protons and electrons in the states described with Landau levels. We find that the direct Urca process can satisfy the kinematic constraints even in density regions where this process could not normally occur in the absence of a magnetic field.
Comments:
15 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2103.01703 [pdf]
PLB(2022)·16 citations
04
[Submitted on 2 Mar 2021]
Triangle singularity mechanism for the $pp \to π^{+} d$ fusion reaction
Natsumi Ikeno🇯🇵 · Raquel Molina🇪🇸 · Eulogio Oset🇪🇸
We develop a model for the $pp \to π^{+} d$ reaction based on the $pp \to Δ (1232) N$ transition followed by $Δ (1232) \to π N^{'}$ decay and posterior fusion of $N N^{'}$ to give the deuteron. We show that the triangle diagram depicting this process develops a triangle singularity leading to a large cross section of this reaction compared to ordinary fusion reactions. The results of the calculation also show that the process is largely dominated by the $pp$ system in $L = 2, S = 0$ , which transfers $J = 2$ to the final $π^{+} d$ system. This feature is shown to be well suited to provide $L = 2, S = 1$ , $J^{tot} = 3$ for $n p$ in the $n p (I = 0) \to π^{-} pp$ followed by $pp \to π^{+} d$ reaction, which has been proposed recently, as a means of describing the so far assumed dibaryon $d^{*} (2380)$ peak.
Comments:
23 pages, 12 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2103.01712 [pdf]
PRC(2021)·35 citations
05
[Submitted on 2 Mar 2021]
Mapping topology to nuclear dilaton-HLS effective field theory for dense baryonic matter
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
We describe the on-going effort to formulate the baryon-quark continuity in terms of a topology change in the equation of state (EoS) of dense baryonic matter in analogy to -- and inspired by -- the mapping of the characteristics of Chern-Simon topological field theory to Kohn-Sham density functional theory in the fractional quantized Hall effect (FQHE). This is done by translating the density-dependent characteristics of the skyrmion-half-skyrmion transition formulated in the presence of hidden local symmetry and (hidden) scale symmetry to the density-dependent parameters of a renormalization-group approach to Fermi-liquid fixed point theory. Predictions made in finite nuclei and infinite compact-star matter are presented.
Comments:
15 pages, no figures. arXiv admin note: text overlap with arXiv:2004.09082
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2103.01860 [pdf]
3 citations
06
[Submitted on 2 Mar 2021]
Investigation of important weak interaction nuclei in presupernova evolution
Jameel-Un Nabi🇵🇰 · Asim Ullah🇵🇰 · Ali Abas Khan🇵🇰
The project aims to investigate most important weak interaction nuclei in the presupernova evolution of massive stars. To achieve the goal, an ensemble containing 728 nuclei in the mass range A = 1--100 was considered. We computed the mass fractions of these nuclei using Saha's equation for predetermined values of \textit{ $T$ }, \textit{ $ρ$ } and \textit{ $Y_{e}$ } and assuming nuclear statistical equilibrium. The nuclear partition functions were obtained using a newly introduced recipe where excited states, up to 10 $M e V$ , were treated as discrete. The weak interaction rates (electron capture (\textit{ec}) and $β$ -decay (\textit{bd})) were calculated in a \textit{totally} microscopic fashion using the proton-neutron quasiparticle random phase approximation (pn-QRPA) model and without assuming the Brink-Axel hypothesis. The calculated rates were coupled with the computed mass fractions to investigate the time rate of change of lepton to baryon fraction of the stellar matter. We compare our results with the previous calculations reported in the literature. Noticeable differences up to orders of magnitude are reported with previous calculations. These differences may influence the evolution of the star in the later stages of presupernova. We present a list of top 50 \textit{ec} and \textit{bd} nuclei which have the largest effect on $Y_{e}$ for conditions after silicon core burning. The competition between the \textit{ec} and \textit{bd} rates in stellar core was investigated and it was found that $Y_{e}$ = 0.424--0.455 is the interval where the \textit{bd} results are bigger than the \textit{ec} rates.
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2103.01909 [pdf]
ApJ(2021)·10 citations
07
[Submitted on 2 Mar 2021] (cross-list from hep-ph)
Diffractive rho + lepton pair production at an electron-ion collider
W. Cosyn🇺🇸 · B. Pire🇫🇷
In high energy electron-ion colliders, a new way to probe nucleon structure becomes available through diffractive reactions, where the incident particle produces a very energetic almost forward particle. QCD describes these reactions as due to the exchange of a Pomeron which may be perturbatively described as a dressed two-gluon state, provided a hard scale allows the factorization of the amplitude in terms of two impact factors convoluted with a Pomeron propagator. We consider here a process where such a description allows to access hadronic structure in terms of the generalized parton distributions, namely the electroproduction of a forward $ρ$ meson and a timelike deeply virtual photon, separated by a large rapidity gap. We explore the dependence of the cross section on the kinematic variables and study the dependence on the non-perturbative inputs (generalized parton distributions, distribution amplitude). Our leading order studies show the cross section is mainly sensitive to the GPD model input, but the small size of the cross sections could prohibit straightforward analysis of this process at planned facilities.
Comments:
published version; corrected typos, conclusion discussion expanded
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.01411 [pdf]
PRD(2021)·12 citations
08
[Submitted on 2 Mar 2021] (cross-list from astro-ph.HE)
Proton-induced activation cross sections in the energy range below 1 GeV
I. V. Moskalenko🇺🇸 · A. A. Andrianov🇷🇺 · A. V. Bytenko🇷🇺 · T. A. Frolova🇷🇺 · R. S. Khalikov🇷🇺 · A. Yu. Konobeev🇩🇪 · Yu. A. Korovin🇷🇺 · T. V. Kulevoy🇷🇺 · I. S. Kuptsov🇷🇺 · K. V. Pavlov🇷🇺 · A. Yu. Stankovskiy🇧🇪 · E. M. Syresin🇷🇺 · Yu. E. Titarenko🇷🇺 · V. D. Vu🇷🇺
(Abridged) Modern studies and industrial applications related to the design, radiation protection, and reliability of nuclear facilities, medical applications, as well as space research and exploration are relying on extensive simulations and modeling. Computer codes realizing semi-classical and quantum molecular dynamics (QMD) approaches are often employed to make up for the lack of accelerator data on many nuclear reactions at intermediate and high energies (>10s of MeV/n) and are in high demand. This contribution focuses on the methodology of generating reliable proton-induced cross sections in the energy range below 1 GeV. We developed a problem-oriented computer framework based on MCNPX and CASCADE/INPE codes to calculate activation cross section data at intermediate and high energies. Goodness of the fits of nucleon-nucleus interaction models to the existing data is evaluated based on elaborated algorithms. The method is based on the analysis of a large set of data and calculated cross sections for different targets and residual nuclei in a wide range of proton energies using numerous criteria. In practice, this could be done by tuning the model parameters and algorithms to fit required experimental data subset, or through achieving unification and consistency of fundamental parameters for all considered reactions. The presented framework is pursuing the latter approach. We use proton-induced reactions on Si and Fe nuclei to illustrate the application of the developed multi-criteria algorithm, where we use all data below 1 GeV available from the EXFOR data library and the IAEA CRP "Benchmark of Spallation Models." We show that the analysis of the predictive power of various intermediate and high-energy models based on the multi-criteria algorithm allows more sophisticated selection of appropriate models in a given energy range and residual nuclei domain.
Comments:
A poster E1.16-0085-21 presented at an event E1.16 "Origin of Cosmic Rays," 43th COSPAR Scientific Assembly (hybrid), 28 Jan - 4 Feb 2021, Sydney, Australia. For a full agenda of the event E1.16, see https://www.cospar-assembly.org/admin/session_cospar.php?session=903
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.01469 [pdf]
0 citations
09
[Submitted on 2 Mar 2021] (cross-list from nucl-ex)
Reevaluating reactor antineutrino spectra with new measurements of the ratio between $^{235}$ U and $^{239}$ Pu $β$ spectra
V. Kopeikin🇷🇺 · M. Skorokhvatov🇷🇺 · O. Titov🇷🇺
We report a reanalysis of the reactor antineutrino energy spectra based on the new relative measurements of the ratio $R =^{e} S_{5} /^{e} S_{9}$ between cumulative $β$ spectra from $^{235}$ U and $^{239}$ Pu, performed at a research reactor in National Research Centre Kurchatov Institute (KI). A discrepancy with the $β$ spectra measured at Institut Laue-Langevin (ILL) was observed, indicating a steady excess of the ILL ratio by the factor of $1.054 \pm 0.002$ . We find a value of the ratio between inverse beta decay cross section per fission for $^{235}$ U and $^{239}$ Pu: $(^{5} σ_{f} /^{9} σ_{f})_{K I} = 1.45 \pm 0.03$ , and then we reevaluate the converted antineutrino spectra for $^{235}$ U and $^{238}$ U. We conclude that the new predictions are consistent with the results of Daya Bay and STEREO experiments.
Comments:
Added more details on the KI experiment. Corrected the error budget for U-238 in Table 1. Results and conclusions unchanged
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2103.01684 [pdf]
PRD(2021)·121 citations
10
[Submitted on 2 Mar 2021] (cross-list from hep-ph)
$J / ψ$ polarization in high multiplicity $pp$ and $p A$ collisions: CGC+NRQCD approach
Tomasz Stebel🇵🇱 · Kazuhiro Watanabe🇺🇸
Quarkonium production mechanism in high multiplicity small collision systems has recently been pursued in the color-glass-condensate (CGC) effective theory combined with non-relativistic QCD (NRQCD) factorization, allowing to study initial state interactions. Quarkonium polarization, potentially measured in future experiments, would help elucidate the quarkonium production mechanism at high multiplicities. In this paper, we provide predictions on $J / ψ$ polarization parameters in high multiplicity proton-proton ( $pp$ ) and proton-nucleus ( $p A$ ) collisions within the CGC+NRQCD framework. Theoretical predictions are given for $J / ψ$ rapidity $2.5 < y_{J / ψ} < 4$ , charged-particle multiplicity pseudorapidity $∣ η_{c h} ∣ < 1$ and energies $S = 13 TeV$ for $pp$ , $S = 8.16 TeV$ for $p A$ collisions. Considering two leptonic frame choices (Collins - Soper and helicity) we find a weak polarization of $J / ψ$ that additionally decreases with growing event activities. No significant system size dependence between $pp$ and $p A$ collisions is obtained - this could be a new constraint to initial state interactions in small collision systems.
Comments:
9 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2103.01724 [pdf]
PRD(2021)·24 citations
11
[Submitted on 2 Mar 2021] (cross-list from hep-ph)
Estimation of Impact Parameter and Transverse Spherocity in heavy-ion collisions at the LHC energies using Machine Learning
Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇹 · Aditya Nath Mishra🇭🇺 · Suman Deb🇮🇳 · Raghunath Sahoo🇮🇳
Recently, machine learning (ML) techniques have led to a range of numerous developments in the field of nuclear and high-energy physics. In heavy-ion collisions, the impact parameter of a collision is one of the crucial observables which has a significant impact on the final state particle production. However, calculation of such a quantity is nearly impossible in experiments as the length scale ranges in the level of a few fermi. In this work, we implement the ML-based regression technique via Boosted Decision Tree (BDT) to obtain a prediction of impact parameter in Pb-Pb collisions at $s_{NN}$ = 5.02 TeV using A Multi-Phase Transport (AMPT) model. In addition, we predict an event shape observable, transverse spherocity in Pb-Pb collisions at $s_{NN}$ = 2.76 and 5.02 TeV using AMPT and PYTHIA8 based on Angantyr model. After a successful implementation in small collision systems, the use of transverse spherocity in heavy-ion collisions has potential to reveal new results from heavy-ion collisions where the production of a QGP medium is already established. We predict the centrality dependent spherocity distributions from the training of minimum bias simulated data and it was found that the predictions from BDT based ML technique match with true simulated data. In the absence of experimental measurements, we propose to implement Machine learning based regression technique to obtain transverse spherocity from the known final state observables in heavy-ion collisions.
Comments:
Same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.01736 [pdf]
PRD(2021)·37 citations
12
[Submitted on 2 Mar 2021] (cross-list from hep-ph)
Searching for axionlike particles with low masses in $pP b$ and $P b P b$ collisions
V. P. Goncalves🇧🇷 · D. E. Martins🇧🇷 · M. S. Rangel🇧🇷
The production of axionlike particles (ALPs) with small masses in ultraperipheral $P b - p$ and $P b - P b$ collisions at the LHC is investigated. The cross section and kinematical distributions associated to the diphoton final state produced in the $γ γ \to a \to γ γ$ subprocesses are estimated considering a realistic set of kinematical cuts. A detailed analysis of the backgrounds is performed and the expected sensitivity to the ALP production is derived. Our results demonstrate that a future experimental analysis of the exclusive diphoton production for the forward rapidities probed by the LHCb detector can improve the existing exclusion limits on the ALP - photon coupling in the mass range 2 GeV $\leq m_{a} \leq$ 5 GeV.
Comments:
6 pages, 3 figures, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.01862 [pdf]
EPJC(2021)·23 citations
13
[Submitted on 2 Mar 2021] (cross-list from hep-ph)
Opportunities of OO and $p$ O collisions at the LHC
Jasmine Brewer🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Wilke van der Schee🇨🇭
This is the summary document of the virtual workshop "Opportunities of OO and $p$ O collisions at the LHC", which took place Feb 4-10, 2021. We briefly review the presented perspectives on the physics opportunities of oxygen--oxygen and proton--oxygen collisions. The full workshop program and the recordings are available at cern.ch/OppOatLHC.
Comments:
Workshop summary (see http://cern.ch/OppOatLHC ), 6 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.01939 [pdf]
124 citations

Affiliations

first authorsco-authorsvia INSPIRE