Nuclear Theory·nucl-th

Tuesday·August 15, 2023

10 papers—3 primary·7 cross-listed

04
Characterizing nuclear modification effects in high-energy O-O collisions at energies available at the CERN Large Hadron Collider: A transport model perspective
Debadatta Behera🇮🇳 · Suman Deb🇫🇷 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳
The present work focuses on Oxygen-Oxygen (O-O) collisions, which are planned at the CERN Large Hadron Collider. Oxygen, being a doubly magic number nucleus, has some very unique features. This study attempts to probe the exotic state of QCD matter in O-O collisions. Additionally, the role of different nuclear density profiles in governing the final state dynamics in ultra-relativistic nuclear collisions is also explored. Using a multi-phase transport model, we obtain the nuclear modification factor ( $R_{AA}$ ) for all charged hadrons and identified particles for O-O collisions at $s_{NN}$ = 7 TeV. Furthermore, we investigate the behavior of $R_{AA}$ as a function of transverse momentum ( $p_{T}$ ) for three centralities (most central, mid-central, and peripheral) considering both $α$ -cluster and Woods-Saxon nuclear density profiles. We also extend this work to study the rapidity dependence of $R_{AA}$ for all charged hadrons. To better understand our findings of O-O collisions, the results are confronted with the available data of $R_{AA}$ for Pb-Pb collisions. The present study sheds light on particle production mechanisms, emphasizing factors influencing particle yield from pre-collision to post-collision stages in the context of O-O collisions.
↳ hep-phhep-exnucl-exnucl-thPRC(2024)·23 citations
05
An effective gauge field theory of the nucleon interactions
Eduard Boos🇷🇺
We discuss the possibility of constructing an effective gauge field theory of the nucleon interations based on the ideas of isotopic invariance as well as hypercharge invariance as a local gauge symmetry and spontaneous breaking of this symmetry. The constructed model predicts the structure of interactions of protons and neutrons with $ρ$ - and $σ$ -mesons, with pi-mesons and photons, as well as interactions of these particles with each other. The Lagrangian of the model consists of several parts parts involving dimension 4 and 5 gauge invariant operators. Feynman rules for physical degrees of freedom as follow from the Lagrangian define the structure of diagrams for one-boson exchanges between nucleons predicting the internucleon one-boson exchange potential as well as nucleon scattering amplitudes. The range of applicability of the model is discussed and estimates are made of the resulting coupling constants. The model predicts the mass of the neutral $ρ^{0}$ -meson to be about $1 M e V$ larger than the mass of the charged mesons $ρ^{\pm}$ . The vector $ω$ -meson, which is a sterile particle with respect to the considered gauge group $S U_{I} (2) \times U_{Y} (1)$ , can be added to the scheme by means of a gauge-invariant operator of dimension 5, as shown in Appendix ~A.
↳ hep-phnucl-thCommun.Theor.Phys.(2024)·0 citations
06
Diquarks and the production of charmed baryons
Hyeongock Yun🇰🇷 · Sungsik Noh🇰🇷 · Sanghoon Lim🇰🇷 · Taesoo Song🇩🇪 · Juhee Hong🇰🇷 · Aaron Park🇰🇷 · Su Houng Lee🇰🇷 · Benjamin Dönigus🇩🇪
Utilizing a quark model characterized by parameters that effectively replicate the masses of ground state hadrons, we illustrate that $(u s)$ or $(d s)$ diquarks exhibit greater compactness in comparison to $(u d)$ diquarks. Concretely, the binding energy of the $(u s)$ diquark - defined as the diquark's mass minus the combined masses of its individual quarks - is found to be stronger than that of the $(u d)$ diquark. This heightened attraction present in $(u s)$ diquarks could lead to enhanced production of $Ξ_{c} / D$ particles in high-energy pp or ultrarelativistic heavy-ion collisions.
↳ hep-phnucl-exnucl-thPLB(2024)·3 citations
07
Forces inside a strongly-coupled scalar nucleon
Xianghui Cao🇨🇳 · Yang Li🇨🇳 · James P. Vary🇺🇸
We investigate the gravitational form factors of a strongly coupled scalar theory that mimic the interaction between the nucleon and the pion. The non-perturbative calculation is based on the light-front Hamiltonian formalism. We renormalize the energy-momentum tensor with a Fock sector dependent scheme. We also systematically analyze the Lorentz structure of the energy-momentum tensor and identify the suitable hadron matrix elements to extract the form factors, avoiding the contamination of spurious contributions. We verify that the extracted form factors obey momentum conservation as well as the mechanical stability condition. From the gravitational form factors, we compute the energy and pressure distributions of the system. Furthermore, we show that utilizing the Hamiltonian eigenvalue equation, the off-diagonal Fock sector contributions from the interaction term can be converted to diagonal Fock sector contributions, yielding a systematic non-perturbative light-front wave function representation of the energies and forces inside the system.
↳ hep-phhep-thnucl-thPRD(2023)·22 citations
08
Exclusive quarkonium photoproduction in $A$ + $A$ UPCs at the LHC in NLO pQCD
Kari J. Eskola🇫🇮 · Christopher A. Flett🇫🇮 · Vadim Guzey🇫🇮 · Topi Löytäinen🇫🇮 · Hannu Paukkunen🇫🇮
We present the first study of coherent exclusive quarkonium ( $J / ψ$ , $Υ$ ) photoproduction in ultraperipheral nucleus-nucleus collisions (UPCs) at the LHC in the framework of collinear factorization and next-to-leading order (NLO) perturbative QCD (pQCD). We make NLO predictions for the $J / ψ$ and $Υ$ rapidity distributions for lead (Pb) and oxygen (O) beams, and quantify their dependence on the factorization/renormalization scale, nuclear parton distribution functions (PDFs) and their uncertainties, and on differences between nuclear PDFs and generalized parton distribution functions (GPDs). We show that within the PDF-originating uncertainties our approach provides a good description of the available $J / ψ$ photoproduction data in Pb+Pb UPCs at the LHC but that the scale uncertainty is significant. We demonstrate that at NLO pQCD the quark contributions are important in the $J / ψ$ case but that gluons clearly dominate the $Υ$ cross sections. We also study how the scale dependence could be tamed by considering O+O/Pb+Pb ratios of the exclusive $J / ψ$ UPC cross sections, and how HERA and p+p/Pb LHC data can help in obtaining better-controlled NLO predictions in the $Υ$ case.
↳ hep-phnucl-thPoS(2024)·1 citation
09
Dibaryons and where to find them
M. Bashkanov🇬🇧 · D.P. Watts🇬🇧 · G. Clash🇬🇧 · M. Mocanu🇬🇧 · M. Nicol🇬🇧
In recent years there has been tremendous progress in the investigation of bound systems of quarks with multiplicities beyond the more usual two- and three-quark systems. Experimental and theoretical progress has been made in the four-, five- and even six-quark sectors. In this paper, we review the possible lightest six-quark states using a simple ansatz based on SU(3) symmetry and evaluate the most promising decay branches. The work will be useful to help focus future experimental searches in this six-quark sector.
↳ hep-phnucl-thJ.Phys.G(2024)·8 citations
10
Deconfinement transition in the revolving bag model
Kazuya Mameda🇯🇵 · Keiya Takizawa🇯🇵
Based on the bag model, we revisit the deconfinement phase transition under rotation. On top of the usual rotational energy for noninteracting particles, we perturbatively analyze the revolution effect of the hadron bag, i.e., of the potential confining quarks. The revolution effect can be phenomenologically translated into the rotational correction to the QCD vacuum energy or the gluon condensate. We demonstrate that if the revolution effect is (is not) taken into account, the transition temperature increases (decreases) as the angular velocity increased. The `revolving bag model' provides a feasible explanation of the recent lattice simulations, contrary to effective models, showing that rotation favors the confined phase.
↳ hep-phnucl-thPLB(2023)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE

Characterizing nuclear modification effects in high-energy O-O collisions at energies available at the CERN Large Hadron Collider: A transport model perspective

An effective gauge field theory of the nucleon interactions

Diquarks and the production of charmed baryons

Forces inside a strongly-coupled scalar nucleon

Exclusive quarkonium photoproduction in A+A UPCs at the LHC in NLO pQCD

Dibaryons and where to find them

Deconfinement transition in the revolving bag model

Affiliations

Exclusive quarkonium photoproduction in $A$ + $A$ UPCs at the LHC in NLO pQCD