Nuclear Theory·nucl-th

Wednesday·March 3, 2021

13 papers—6 primary·7 cross-listed

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

Diffractive rho + lepton pair production at an electron-ion collider

Proton-induced activation cross sections in the energy range below 1 GeV

Reevaluating reactor antineutrino spectra with new measurements of the ratio between 235U and 239Pu β spectra

J/ψ polarization in high multiplicity pp and pA collisions: CGC+NRQCD approach

Estimation of Impact Parameter and Transverse Spherocity in heavy-ion collisions at the LHC energies using Machine Learning

Searching for axionlike particles with low masses in pPb and PbPb collisions

Opportunities of OO and pO collisions at the LHC

Affiliations

Reevaluating reactor antineutrino spectra with new measurements of the ratio between $^{235}$ U and $^{239}$ Pu $β$ spectra

$J / ψ$ polarization in high multiplicity $pp$ and $p A$ collisions: CGC+NRQCD approach

Searching for axionlike particles with low masses in $pP b$ and $P b P b$ collisions

Opportunities of OO and $p$ O collisions at the LHC