Nuclear Theory·nucl-th

Monday·September 12, 2022

9 papers—4 primary·5 cross-listed

01
[Submitted on 8 Sept 2022]
Bound states and electromagnetic radiation of relativistically rotating cylindrical wells
Matteo Buzzegoli🇺🇸 · Kirill Tuchin🇺🇸
We compute the effect of rigid rotation on the non-relativistic bound states. The energy levels of the bound states increase with the angular velocity of rotation until at certain value of the angular velocity they are completely pushed out into the continuum which corresponds to dissociation of the bound states. When the angular velocity exceeds the critical value at which the ground state disappears into the continuum, no bound state is possible. This effect should have important consequences for the phenomenology of the quark-gluon plasma. One of the ways to study it experimentally is to observe the electromagnetic radiation emitted by a rotating bound state. We compute the corresponding intensity of electromagnetic radiation and show that it strongly depends on the angular velocity of rotation.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.03991 [pdf]
NPA(2023)·11 citations
02
[Submitted on 9 Sept 2022]
Enhanced pion-to-proton ratio at the onset of the QCD phase transition
Thiranat Bumnedpan🇹🇭 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪 · Ayut Limphirat🇹🇭 · Christoph Herold🇹🇭
The pion-to-proton ratio is identified as a potential signal for a non-equilibrium first-order chiral phase transition in heavy-ion collisions, as the pion multiplicity is directly related to entropy production. To showcase this effect, a non-equilibrium Bjorken expansion starting from realistic initial conditions along a Taub adiabat is used to simulate the entropy production. Different dynamical criteria to determine the final entropy-per-baryon number are investigated and matched to a hadron resonance gas model along the chemical freeze out curve to obtain the final pion and proton numbers. We detect a strong enhancement of their multiplicity ratio at the energies where the system experiences a strong phase transition as compared to a smooth crossover which shows almost no enhancement.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.04096 [pdf]
PLB(2022)·7 citations
03
[Submitted on 9 Sept 2022]
Interplay between core and corona from small to large systems
Yuuka Kanakubo🇯🇵 · Yasuki Tachibana🇯🇵 · Tetsufumi Hirano🇯🇵
We present new results in $p$ + $p$ and Pb+Pb collisions at the LHC energies from the updated dynamical core--corona initialization framework (DCCI2). The fractions of final hadron yields originating from equilibrated and non-equilibrated components are extracted as functions of multiplicity. We find that the contributions from non-equilibrated components are non-negligible even in Pb+Pb collisions and affect $p_{T}$ -integrated multi-particle correlations. These suggest the importance of non-equilibrated components for the sophisticated extraction of properties of the quark gluon plasma from comparisons between dynamical frameworks and experimental data.
Comments:
4 pages, 2 figures, contribution to the proceedings of the 20th International Conference on Strangeness in Quark Matter (SQM2022)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.04110 [pdf]
EPJ Web Conf.(2023)·3 citations
04
[Submitted on 9 Sept 2022]
Interactions between heavy quarks and tilted QGP fireballs in 200 AGeV Au+Au collisions
Ze-Fang Jiang🇨🇳 · Shanshan Cao🇨🇳 · Wen-Jing Xing🇨🇳 · Xiaowen Li🇨🇳 · Ben-Wei Zhang🇨🇳
Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions. Using an improved Langevin model coupled to a (3+1)-dimensional viscous hydrodynamic model, we study the nuclear modification factor ( $R_{AA}$ ), directed flow ( $v_{1}$ ) and elliptic flow ( $v_{2}$ ) coefficients of heavy mesons and their decayed electrons at the RHIC energy. We find that the counter-clockwise tilt of the nuclear matter in the reaction plane results in a positive (negative) heavy flavor $v_{1}$ in the backward (forward) rapidity region, whose magnitude increases with the heavy quark transverse momentum. The difference in the heavy flavor $R_{AA}$ between different angular regions is also proposed as a complementary tool to characterize the asymmetry of the medium profile. Our model results are consistent with currently available data at RHIC and provide predictions that can be tested by future measurements.
Comments:
10 pages, 6 figures, comments are welcome
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.04143 [pdf]
CPC(2023)·3 citations
05
[Submitted on 8 Sept 2022] (cross-list from hep-ph)
The LPM effect in sequential bremsstrahlung: incorporation of "instantaneous'' interactions for QCD
Peter Arnold🇺🇸 · Tyler Gorda🇩🇪 · Shahin Iqbal🇵🇰
The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We continue study of the case when the coherence lengths (formation lengths) of two consecutive splitting processes overlap, avoiding soft-emission approximations. Previous work made a ``nearly-complete'' calculation of the effect of overlapping formation times on gluonic splittings such as $g \to g g \to g g g$ (with simplifying assumptions such as an infinite QCD medium and the large- $N_{c}$ limit). In this paper, we extend those previous rate calculations from nearly-complete to complete by including processes involving the exchange of longitudinally-polarized gluons. In the context of Lightcone Pertubation Theory, used earlier for the ``nearly-complete'' calculation, such exchanges are instantaneous in lightcone time and have their own diagrammatic representation.
Comments:
33 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.03971 [pdf]
JHEP(2022)·12 citations
06
[Submitted on 9 Sept 2022] (cross-list from hep-ph)
Fixed-target charmonium production and pion parton distributions
Wen-Chen Chang🇹🇼 · Jen-Chieh Peng🇺🇸 · Stephane Platchkov🇫🇷 · Takahiro Sawada🇯🇵
We investigate how charmonium hadroproduction at fixed-target energies can be used to constrain the gluon distribution in pions. Using nonrelativistic QCD (NRQCD) formulation, the $J / ψ$ and $ψ (2 S)$ cross sections as a function of longitudinal momentum fraction $x_{F}$ from pions and protons colliding with light targets, as well as the $ψ (2 S)$ to $J / ψ$ cross section ratios, are included in the analysis. The color-octet long-distance matrix elements are found to have a pronounced dependence on the pion parton distribution functions (PDFs). This study shows that the $x_{F}$ differential cross sections of pion-induced charmonium production impose strong constraints on the pion's quark and gluon PDFs. In particular, the pion PDFs with larger gluon densities provide a significantly better description of the data. It is also found that the production of the $ψ (2 S)$ state is associated with a larger quark-antiquark contribution, compared with $J / ψ$ .
Comments:
15 pages, 10 figures and 23-page supplementary materials. Published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.04072 [pdf]
PRD(2023)·11 citations
07
[Submitted on 9 Sept 2022] (cross-list from hep-lat)
Moments and power corrections of longitudinal and transverse proton structure functions from lattice QCD
M. Batelaan🇦🇺 · K. U. Can🇦🇺 · A. Hannaford-Gunn🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P. E. L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stüben🇩🇪 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
We present a simultaneous extraction of the moments of $F_{2}$ and $F_{L}$ structure functions of the proton for a range of photon virtuality, $Q^{2}$ . This is achieved by computing the forward Compton amplitude on the lattice utilizing the second-order Feynman-Hellmann theorem. Our calculations are performed on configurations with two different lattice spacings and volumes, all at the $S U (3)$ symmetric point. We find the moments of $F_{2}$ and $F_{L}$ in good agreement with experiment. Power corrections turn out to be significant. This is the first time the $Q^{2}$ dependence of the lowest moment of $F_{2}$ has been quantified.
Comments:
14 pages, 11 figures, 2 tables. Version to appear in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.04141 [pdf]
PRD(2023)·14 citations
08
[Submitted on 9 Sept 2022] (cross-list from hep-ph)
The $X (3872)$ 's excitation and its connection with production at hadron colliders
M.C. Gordillo🇪🇸 · F. De Soto🇪🇸 · J. Segovia🇪🇸
The LHCb collaboration has found that the production rate of $X (3872)$ in proton-proton collisions decreases as final state particle multiplicity increases. Moreover, the ALICE experiment at CERN has observed that the number of deuterons produced increases with multiplicity, a behavior that is qualitatively different from that of the $X (3872)$ . These experimental findings may point to a compact structure for the $X (3872)$ or, at least, that its hadronization could proceed through a charm-anticharm core. We have recently used a diffusion Monte Carlo method to solve the many-body Schrödinger equation that describes the $X (3872)$ as a $c c ˉ q q ˉ$ tetraquark system with quantum numbers $I^{G} (J^{P C}) = 0^{+} (1^{++})$ and $1^{-} (1^{++})$ . According to our structural analysis, the quark--(anti-)quark correlations resemble light-meson--heavy-meson molecules of type $ω J / ψ$ and $ρ J / ψ$ , rather than the most extended $D D ˉ^{*}$ interpretation. It was argued that this fact may be the key to make compatible the molecular features of the $X (3872)$ with its production observables. The same formalism allows us to compute the first color excited $c c ˉ q q ˉ$ tetraquark state with either $I^{G} (J^{P C}) = 0^{+} (1^{++})$ or $1^{-} (1^{++})$ . A bound-state is found in each channel, their masses are around 4.0 GeV which is an energy region where many new exotic candidates have been collected by the Particle Data Group. Concerning their structural properties, these states cluster in a compact diquark-antidiquark arrangement which matches perfectly with a so-called Born-Oppenheimer tetraquark configuration. The promptly production rates of these states in proton-proton, proton-nucleus and nucleus-nucleus collisions should fall off equal to or even faster than those of the $X (3872)$ .
Comments:
5 pages, 1 figure. arXiv admin note: text overlap with arXiv:2105.11976
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.04221 [pdf]
PRD(2022)·10 citations
09
[Submitted on 9 Sept 2022] (cross-list from hep-ph)
Heavy-flavor meson and baryon production in high-energy nucleus-nucleus collisions
Andrea Beraudo🇮🇹 · Arturo De Pace🇮🇹 · Daniel Pablos Alfonso🇮🇹 · Francesco Prino🇮🇹 · Marco Monteno🇮🇹 · Marzia Nardi🇮🇹
We present a new model for the description of heavy-flavor hadronization in relativistic heavy-ion collisions. We explore its effect on the charmed hadron yields and kinematic distributions once the latter is applied at the end of transport calculations used to simulate the propagation of heavy quarks in the deconfined fireball produced in the collision. The model is based on the formation of color-singlet clusters through the recombination of charm quarks with light antiquarks or diquarks from the same fluid cell. This local mechanism of color neutralization leads to a strong space-momentum correlation, which provides a substantial enhancement of charmed baryon production and of the collective flow of all charmed hadrons.
Comments:
SQM 2022 proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.04239 [pdf]
EPJ Web Conf.(2023)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE