Nuclear Theory·nucl-th

Thursday·July 30, 2020

9 papers—3 primary·6 cross-listed

01
[Submitted on 29 Jul 2020]
Strange hadron production in a quark combination model in Au+Au collisions at RHIC energies
Jun Song🇨🇳 · Xiao-feng Wang🇨🇳 · Hai-hong Li🇨🇳 · Rui-qin Wang🇨🇳 · Feng-lan Shao🇨🇳
We apply a quark combination model to study yield densities and transverse momentum ( $p_{T}$ ) spectra of strange (anti-)hadrons at mid-rapidity in central Au+Au collisions at $s_{N N} =$ 7.7, 11.5, 19.6, 27, 39 and 200 GeV. We show that experimental data for $p_{T}$ spectra of (anti-)hadrons in these collisions can be systematically described by the equal velocity combination of constituent quarks and antiquarks at hadronization. We obtain $p_{T}$ spectra of quarks and antiquarks at hadronization and study their collision energy dependence. We also reproduce the yield densities of hadrons and anti-hadrons. In particular, we demonstrate that yield ratios of anti-hadrons to hadrons $K^{-} / K^{+}$ , $p ˉ / p$ , $Λ ˉ /Λ$ , $Ξ ˉ^{+} / Ξ^{-}$ and $Ω ˉ^{+} / Ω^{-}$ simply correlate with each other and their experimental data except $Ω ˉ^{+} / Ω^{-}$ at $s_{N N} =$ 7.7 GeV are systematically described by the model. These results suggest that the equal velocity combination mechanism for quarks and antiquarks at hadronization plays an important role in Au+Au collisions at low RHIC energies ( $s_{N N} \geq$ 11.5 GeV).
Comments:
14 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.14588 [pdf]
PRC(2021)·13 citations
02
[Submitted on 29 Jul 2020]
Applications of the chiral potential with the semi-local regularization in momentum space to the disintegration processes
V.Urbanevych🇵🇱 · R.Skibiński🇵🇱 · H.Witała🇵🇱 · J.Golak🇵🇱 · K.Topolnicki🇵🇱 · A.Grassi🇵🇱 · E.Epelbaum🇩🇪 · H.Krebs🇩🇪
We apply the chiral potential with the momentum space semi-local regularization to the $^{2}$ H and $^{3}$ He photodisintegration processes and to the (anti)neutrino induced deuteron breakup reactions. Specifically, the differential cross section, the photon analyzing power and the final proton polarization have been calculated for the deuteron photodisintegration at the photon energies 30 MeV and 100 MeV. For the $^{3}$ He photodisintegration predictions for the semi-inclusive and exclusive differential cross sections are presented for the photon energies up to 120 MeV. The total cross section is calculated for the (anti)neutrino disintegrations of the deuteron for the (anti)neutrino energies below 200 MeV. The predictions based on the Argonne V18 potential or on the older chiral force with regularization applied in coordinate space are used for comparison. Using the fifth order chiral nucleon-nucleon potential supplemented with dominant contributions from the sixth order allows us to obtain converged predictions for the regarded reactions and observables. Our results based on the newest semi-local chiral potentials show even smaller cutoff dependence for the considered electroweak observables than the previously reported ones with a coordinate-space regulator. However, some of the studied polarization observables in the deuteron photodisintegration process reveal more sensitivity to the regulator value than the unpolarized cross section. The chiral potential regularized semi-locally in momentum space yields also fast convergence of results with the chiral order. These features make the used potential a high quality tool to study electroweak processes.
Comments:
18 pages, 14 pdf figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.14836 [pdf]
PRC(2021)·5 citations
03
[Submitted on 29 Jul 2020]
Simple relativistic quark models
Sirajudheen Kuthini Kunhammed🇺🇸 · W. N. Polyzou🇺🇸
A class of phenomenological relativistic models of hadronic systems motivated by QCD that have dual representations as models of mesons and nucleons or quarks and gluons is investigated. These models are designed to provided qualitative insight into the role of sea quarks in hadronic structure and reactions. The model assumption is that the Hamiltonian can be divided into two parts; one that involves degrees of freedom in the same connected local and global color singlet and the remaining interactions that allow the connected local and global color singlets to interact. The first class of interactions results in infinite towers of bare "particles" with hadronic quantum numbers. All but a finite number of these remain stable when the second class of interactions is included. The model interactions are expressed in terms of sub-hadronic degrees of freedom, which determine the bare hadronic spectrum and the interactions involving the bare hadrons in terms of a small number of sub-hadronic model parameters. As a first test, this paper considers the simplest case of mesons that interact via a string-breaking interaction. One virtue of this model is that all of the bare meson masses and eigenfunctions can be computed analytically. In addition, the string breaking interaction leads to production vertices that can also be computed analytically. The relativistic wave functions have a light-front kinematic symmetry. The goal is to find a simple relativistic quantum mechanical model based on sub-hadronic degrees of freedom that can provide an efficient, qualitatively consistent description of hadronic masses, lifetimes, cross sections, sea quark effects, and electromagnetic properties. The simplicity of the model makes it a potentially useful tool to study the impact of sea quarks on hadronic structure and reactions.
Comments:
44 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.14892 [pdf]
PRC(2020)·4 citations
04
[Submitted on 28 Jul 2020] (cross-list from hep-ph)
QCD resummation on single hadron transverse momentum distribution with the thrust axis
Zhong-Bo Kang🇺🇸 · Ding Yu Shao🇺🇸 · Fanyi Zhao🇺🇸
We derive the transverse momentum dependent (TMD) factorization and resummation formula of the unpolarized transverse momentum distribution ( $j_{T}$ ) for the single hadron production with the thrust axis in electron-positron collision. Two different kinematic regions are considered, including small transverse momentum limit $j_{T} ≪ Q$ , and joint transverse momentum and threshold limit $j_{T} ≪ Q (1 - z_{h}) ≪ Q$ , where $Q$ and $z_{h}$ are the hard scattering energy and the observed hadron momentum fraction. Using effective theory methods, we resum logarithms $ln (Q / j_{T})$ and $ln (1 - z_{h})$ to all orders. In the end we present the differential cross sections and Gaussian widths calculated for the inclusive charged pion production and find that our results are consistent with the measurements reported by the Belle collaboration.
Comments:
25 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2007.14425 [pdf]
JHEP(2020)·28 citations
05
[Submitted on 28 Jul 2020] (cross-list from hep-ex)
The Large Hadron-Electron Collider at the HL-LHC
P. Agostini🇪🇸 · H. Aksakal🇹🇷 · S. Alekhin🇩🇪 · P. P. Allport🇬🇧 · N. Andari🇫🇷 · K. D. J. Andre🇬🇧 · D. Angal-Kalinin🇬🇧 · S. Antusch🇨🇭 · L. Aperio Bella🇨🇳 · L. Apolinario🇵🇹 · R. Apsimon🇬🇧 · A. Apyan🇦🇲 and 325 other authors
The Large Hadron electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High Luminosity--Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron-proton and proton-proton operation. This report represents an update of the Conceptual Design Report (CDR) of the LHeC, published in 2012. It comprises new results on parton structure of the proton and heavier nuclei, QCD dynamics, electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics in extending the accessible kinematic range in lepton-nucleus scattering by several orders of magnitude. Due to enhanced luminosity, large energy and the cleanliness of the hadronic final states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, the report represents a detailed updated design of the energy recovery electron linac (ERL) including new lattice, magnet, superconducting radio frequency technology and further components. Challenges of energy recovery are described and the lower energy, high current, 3-turn ERL facility, PERLE at Orsay, is presented which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution and calibration goals which arise from the Higgs and parton density function physics programmes. The paper also presents novel results on the Future Circular Collider in electron-hadron mode, FCC-eh, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies.
Comments:
373 pages, many figures, to be published by J. Phys. G
Subjects:
High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2007.14491 [pdf]
J.Phys.G(2021)·441 citations
06
[Submitted on 29 Jul 2020] (cross-list from hep-ph)
Full resummation analysis of jet quenching and tests of the QCD Equation of State
Xabier Feal🇺🇸
Jet quenching has become a fundamental tool to study the hot QCD matter produced in heavy ion collisions. While important theoretical and experimental advances have been made in the last two decades, the extraction of the medium properties and the comparison with finite temperature QCD is still particularly worrisome. In this work we show that improvements in the calculation of the medium-induced gluon spectrum are required for a correct extraction of the parameters without temperature issues. In particular, we employ an improved numerical implementation of multiple hard scatterings that resums all terms in the opacity expansion beyond the Gaussian approximation. We find significant differences in the extracted medium parameters when comparing with two of the most used approximations in phenomenological analyses to date, the first order opacity expansion and the Gaussian approximation. We also make a first attempt to compare the extracted medium parameters with lattice results.
Comments:
7 pages, 2 figures; 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.14834 [pdf]
PoS(2021)·0 citations
07
[Submitted on 29 Jul 2020] (cross-list from hep-ph)
Neutrinoless Double-Electron Capture
K. Blaum🇩🇪 · S. Eliseev🇩🇪 · F. A. Danevich🇺🇦 · V. I. Tretyak🇺🇦 · Sergey Kovalenko🇨🇱 · M. I. Krivoruchenko🇷🇺 · Yu. N. Novikov🇷🇺 · J. Suhonen🇫🇮
Double-beta processes play a key role in the exploration of neutrino and weak interaction properties, and in the searches for effects beyond the Standard Model. During the last half century many attempts were undertaken to search for double-beta decay with emission of two electrons, especially for its neutrinoless mode ( $0 ν 2 β^{-}$ ), the latter being still not observed. Double-electron capture (2EC) was not in focus so far because of its in general lower transition probability. However, the rate of neutrinoless double-electron capture ( $0 ν 2$ EC) can experience a resonance enhancement by many orders of magnitude in case the initial and final states are energetically degenerate. In the resonant case, the sensitivity of the $0 ν 2$ EC process can approach the sensitivity of the $0 ν 2 β^{-}$ decay in the search for the Majorana mass of neutrinos, right-handed currents, and other new physics. We present an overview of the main experimental and theoretical results obtained during the last decade in this field. The experimental part outlines search results of 2EC processes and measurements of the decay energies for possible resonant $0 ν$ 2EC transitions. An unprecedented precision in the determination of decay energies with Penning traps has allowed one to refine the values of the degeneracy parameter for all previously known near-resonant decays and has reduced the rather large uncertainties in the estimate of the $0 ν 2$ EC half-lives. The theoretical part contains an updated analysis of the electron shell effects and an overview of the nuclear structure models, in which the nuclear matrix elements of the $0 ν 2$ EC decays are calculated. One can conclude that the decay probability of $0 ν$ 2EC can experience a significant enhancement in several nuclides.
Comments:
68 pages, 14 tables, 19 figures, accepted for publication in Reviews of Modern Physics
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2007.14908 [pdf]
RMP(2020)·68 citations
08
[Submitted on 29 Jul 2020] (cross-list from hep-ph)
Photon radiation from quark-gluon plasma by means of chiral anomalies without magnetic field
Kirill Tuchin🇺🇸
We discuss a new channel of photon emission from the quark-gluon plasma, which opens up as photon acquires a tachyonic mass in the presence of the CP-odd topological domains generated by the chiral anomaly. It allows photon radiation through the decay $q \to q γ$ and annihilation $q q ˉ \to γ$ processes closely related to the chiral Cherenkov radiation. Unlike previous proposals this mechanism does not require an external magnetic field. The differential photon emission rate per unit volume is computed and shown to be comparable to the rate of photon emission in conventional processes.
Comments:
contribution to the "10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions"
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.14939 [pdf]
PoS(2021)·0 citations
09
[Submitted on 29 Jul 2020] (cross-list from hep-ph)
Dynamics of QCD Matter -- current status
Amaresh Jaiswal🇮🇳 · Najmul Haque🇮🇳 · Aman Abhishek🇮🇳 · Raktim Abir🇮🇳 · Aritra Bandyopadhyay🇧🇷 · Khatiza Banu🇮🇳 · Samapan Bhadury🇮🇳 · Sumana Bhattacharyya🇮🇳 · Trambak Bhattacharyya🇷🇺 · Deeptak Biswas🇮🇳 · H. C. Chandola🇮🇳 · Vinod Chandra🇮🇳 and 49 other authors
In this article, there are 18 sections discussing various current topics in the field of relativistic heavy-ion collisions and related phenomena, which will serve as a snapshot of the current state of the art. Section 1 reviews experimental results of some recent light-flavored particle production data from ALICE collaboration. Other sections are mostly theoretical in nature. Very strong but transient magnetic field created in relativistic heavy-ion collisions could have important observational consequences. This has generated a lot of theoretical activity in the last decade. Sections 2, 7, 9, 10 and 11 deal with the effects of the magnetic field on the properties of the QCD matter. There are several unanswered questions about the QCD phase diagram. Sections 3, 11 and 18 discuss various aspects of the QCD phase diagram and phase transitions. Recent years have witnessed interesting developments in foundational aspects of hydrodynamics and their application to heavy-ion collisions. Sections 12, 15, 16 and 17 of this article probe some aspects of this exciting field. Transport coefficients together with their temperature- and density-dependence, are essential inputs in hydrodynamical calculations. Sections 5, 8 and 14 deal with calculation/estimation of various transport coefficients (shear and bulk viscosity, thermal conductivity, relaxation times, etc.) of quark matter and hadronic matter. Sections 4, 6 and 13 deals with interesting new developments in the field. Section 4 discusses color dipole gluon distribution function at small transverse momentum in the form of a series of Bells polynomials. Section 6 discusses the properties of Higgs boson in the quark gluon plasma using Higgs-quark interaction. Section 13 discusses modification of coalescence model to incorporate viscous corrections and application of this model.
Comments:
109 pages, 49 captioned figures, compilation of the contributions as presented in the `Workshop on Dynamics of QCD Matter', 15th to 17th August 2019, NISER Bhubaneswar, India, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2007.14959 [pdf]
IJMPE(2021)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE