Nuclear Theory·nucl-th

Tuesday·September 10, 2024

21 papers—6 primary·15 cross-listed

01
[Submitted on 6 Sept 2024]
Weak decays in superheavy nuclei
A. Ravlić · W. Nazarewicz
Superheavy nuclei represent the heaviest atoms and nuclides known at the limit of mass and charge. The observed superheavy nuclei are all proton-rich; they decay primarily by emitting $α$ particles and fission, with a possible small electron capture (EC) branch. Due to the huge atomic numbers and associated relativistic effects, EC-decays of superheavy systems are expected to differ from what is known in lighter nuclei. In this paper, using the quantified relativistic nuclear density functional theory and the quasiparticle random-phase approximation with the interaction optimized to experimental $β^{-}$ -decay half-lives and Gamow-Teller resonance energies, we study the EC/ $β^{\pm}$ -decays in $Z = 101 - 118$ nuclei. Both allowed ( $1^{+}$ ) and first-forbidden ( $0^{-}, 1^{-}$ and $2^{-}$ ) transitions are considered. We show that the first-forbidden $1^{-}$ transitions dominate the decay rates in almost all studied nuclei. For proton-rich nuclei, EC dominates over $β^{+}$ decay. We identify 44 nuclei with EC/ $β^{+}$ branching ratio larger than 5\%, indicating a possible competition with $α$ -decay and spontaneous fission channels.
Comments:
7 pages, 4 figures, submitted for publication
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2409.04620 [pdf]
PRC(2025)·7 citations
02
[Submitted on 7 Sept 2024]
Effect of vector meson spin coherence on the measurements of chiral magnetic effect in heavy-ion collisions
Zhiyi Wang🇨🇳 · Jinhui Chen🇨🇳 · Diyu Shen🇨🇳 · Aihong Tang🇺🇸 · Gang Wang🇺🇸
The chiral magnetic effect (CME) in heavy-ion collisions reflects the local violation of $P$ and $C P$ symmetries in strong interactions and manifests as electric charge separation along the direction of the magnetic field created by the wounded nuclei. The experimental observables for the CME, such as the $γ_{112}$ correlator, the $R_{Ψ_{2}} (Δ S)$ correlator, and the signed balance functions, however, are also subject to non-CME backgrounds, including those from resonance decays. A previous study showed that the CME observables are affected by the diagonal component of the spin density matrix, the $ρ_{00}$ for vector mesons. In this work, we study the contributions from the other elements of the spin density matrix using a toy model and a multiphase transport model. We find that the real part of the $ρ_{1 - 1}$ component, $Re ρ_{1 - 1}$ , affects the CME observables in a manner opposite to that of the $ρ_{00}$ . All three aforementioned CME observables show a linear dependence on $Re ρ_{1 - 1}$ in the model calculations, supporting our analytical derivations. The rest elements of the spin density matrix do not contribute to the CME observables. The off-diagonal terms in the spin density matrix indicate spin coherence and may be nonzero in heavy-ion collisions due to local spin polarization or spin-spin correlations. Thus, $Re ρ_{1 - 1}$ , along with $ρ_{00}$ , could play a significant role in interpreting measurements in search of the CME.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2409.04675 [pdf]
PRC(2025)·5 citations
03
[Submitted on 7 Sept 2024]
Partial-wave analysis to determine the spin of $Ξ (1690)^{-}$ and $Ξ (1820)^{-}$ produced in $p p$ annihilation
Deepak Pachattu🇮🇳
Recently [arXiv:2201.03852v2] the PANDA collaboration studied the feasibility of determining the spin and parity of the $Ξ (1690)^{-}$ and $Ξ (1820)^{-}$ resonances in the $Λ K^{-}$ system produced in $p ˉ p$ collisions via the reaction channel $p p \to Ξ ˉ^{+} Λ K^{-}$ . This contribution aims to study these reactions using a model-independent irreducible tensor formalism developed earlier. This study leads us to identify the partial-wave amplitude, which would be zero if $Ξ (1690)^{-}$ or $Ξ (1820)^{-}$ had spin-1/2, provided these resonances are produced at threshold (s-wave production).
Comments:
7 pages, uses RevTeX, no figures or tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex)
arXiv:
2409.04886 [pdf]
EPJA(2025)·0 citations
04
[Submitted on 8 Sept 2024]
Nuclear transparency and shadowing of the two-step process in the $A (e, e^{'} π^{+})$ reaction
Tae Keun Choi🇰🇷 · Kook-Jin Kong🇰🇷 · Byung-Geel Yu🇰🇷
We investigate nuclear transparency induced by pion electroproduction on nuclei, $A (e, e^{'} π^{+})$ , with our interest in the role of the two-step process in the Glauber multiple scattering theory. Based on the framework in which the quantum diffusion model is incorporated into the Glauber theory, the experimental data in the range of photon virtuality $0.5 < Q^{2} < 10$ GeV $^{2} / c^{2}$ are analyzed, including the recent JLab data at the 6 GeV electron beam together with the proposal for the 12 GeV upgrade. Application of the quantum diffusion model during the formation length of the quark/antiquark $(q q ˉ)$ structure of a pion reproduces the increase in the nuclear transparency up to high $Q^{2}$ , showing evidence of color transparency. In contrast, through the coherent length of the $γ^{*}$ fluctuation into $ρ^{0}$ , the two-step process with the $ρN$ scattering cross section chosen to be $σ_{ρN} = σ_{π N}$ contributes to a reduction of the nuclear transparency in the whole range of $Q^{2}$ . Combined with the one-step process (direct photon coupling) usually adopted in the original formulation of the Glauber theory, this reaction mechanism provides another source of the $Q^{2}$ dependence of the transparency at low virtualities through the shadowing in the initial state interaction. By the further absorption due to the shadowing, a better agreement is obtained with the pion transparency measured in the $A (e, e^{'} π^{+})$ reaction for $^{12}$ C, $^{27}$ Al, $^{63}$ Cu, and $^{197}$ Au nuclei. A discussion of the $Q^{2}$ dependence of the parameter $α$ for the transparency $T_{A} = A^{α - 1}$ is given.
Comments:
7 pages, 4 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2409.05129 [pdf]
PRC(2025)·4 citations
05
[Submitted on 9 Sept 2024]
Emergent chirality and superfluidity of parity-doubled baryons in neutron stars
Shigehiro Yasui🇯🇵 · Muneto Nitta🇯🇵 · Chihiro Sasaki🇯🇵
We propose novel superfluids induced by the parity-doubled baryons. The parity-doubled baryons, i.e., a nucleon $N (940)$ with spin-parity $J^{P} = 1/ 2^{+}$ and an excited nucleon $N^{*} (1535)$ with $J^{P} = 1/ 2^{-}$ in vacuum, become degenerate at sufficiently high density where the chiral symmetry is restored. In this study, we extend the conventional $U (1)$ chiral symmetry to the higher dimensional symmetries, dubbed emergent chiral symmetries, including the naive and mirror assignments as their subgroups. Starting with the Lagrangian up to four-point interactions among the neutron $n$ and its chiral partner $n^{*}$ , neutral components in $N$ and $N^{*}$ , in pure neutron matter, we investigate the properties of the ground state with a pairing gap generated by the $n$ and $n^{*}$ in the mean-field approximation. We find vector-type condensates that induce the dynamical breaking of a new class of internal symmetries, emergent chiral symmetries, as well as the baryon number and the rotational symmetries of the real space, indicating the appearance of massless Nambu-Goldstone bosons consisting of six quarks: emergent pions, superfluid phonons, and magnons, respectively. We also study the fermionic excitation modes at low-energy scales, and show that they exhibit a spatial anisotropy of the propagation at the Dirac cone in momentum space. Some phenomenological implications are advocated, shedding new light on the properties of neutron stars.
Comments:
23 pages, 5 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th); Superconductivity (cond-mat.supr-con); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2409.05670 [pdf]
PRD(2025)·5 citations
06
[Submitted on 9 Sept 2024]
A simple explanation of the absence of the spherical nuclei with the hidden-color states
Tao Wang🇨🇳
Inspired by the EMC effect, the Cd puzzle and the SU3-IBM, a hypothesis can be given for a nucleus, that only the nucleus itself is a trivial (0,0) representation of the SU(3) group, which leads to the simple conclusion that spherical nucleus does not exist and the spherical mean field is not allowed. The key conclusion is that the whole nucleus should have many hidden-color states, and the quark-gluon degrees of freedom are required even at the low-energy excitation of the nucleus.
Comments:
For the first time, the clear evidence for the existence of the color degree of freedom of the nucleons in the nucleus is given. Comments are welcome
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2409.05723 [pdf]
0 citations
07
[Submitted on 6 Sept 2024] (cross-list from quant-ph)
Entropy-driven entanglement forging
Axel Pérez-Obiol🇪🇸 · Sergi Masot-Llima🇪🇸 · Antonio M. Romero🇪🇸 · Javier Menéndez🇪🇸 · Arnau Rios🇪🇸 · Artur García-Sáez🇪🇸 · Bruno Juliá-Díaz🇪🇸
Simulating physical systems with variational quantum algorithms is a well-studied approach, but it is challenging to implement in current devices due to demands in qubit number and circuit depth. We show how limited knowledge of the system, namely the entropy of its subsystems, its entanglement structure or certain symmetries, can be used to reduce the cost of these algorithms with entanglement forging. To do so, we simulate a Fermi-Hubbard one-dimensional chain with a parametrized hopping term, as well as atomic nuclei $^{28}$ Ne and $^{60}$ Ti with the nuclear shell model. Using an adaptive variational quantum eigensolver we find significant reductions in both the maximum number of qubits (up to one fourth) and the amount of two-qubit gates (over an order of magnitude) required in the quantum circuits. Our findings indicate that our method, entropy-driven entanglement forging, can be used to adjust quantum simulations to the limitations of noisy intermediate-scale quantum devices.
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2409.04510 [pdf]
EPJA(2026)·10 citations
08
[Submitted on 6 Sept 2024] (cross-list from astro-ph.HE)
Constraining the nuclear equation of state from orbits of primordial black holes inside neutron stars
Anna Chen🇺🇸 · Juan Diego DelPrado🇺🇸 · Thomas W. Baumgarte🇺🇸 · Stuart L. Shapiro🇺🇸
Lacking terrestrial experimental data, our best constraints on the behavior of matter at high densities up to and above nuclear density arise from observations of neutron stars. Current constraints include those based on measurements of stellar masses, radii, and tidal deformabilities. Here we explore how orbits of primordial black holes - should they exist - inside neutron stars could provide complementary constraints on the nuclear equation of state (EOS). Specifically, we consider a sample of candidate EOSs, construct neutron star models for these EOSs, and compute orbits of primordial black holes inside these stars. We discuss how the pericenter advance of eccentric orbits, i.e. orbital precession, results in beat phenomena in the emitted gravitational wave signal. Observing this beat frequency could constrain the nuclear EOS and break possible degeneracies arising from other constraints, as well as provide information about the host star.
Comments:
12 pages, 9 figures; PRD in press
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2409.04526 [pdf]
PRD(2024)·1 citation
09
[Submitted on 7 Sept 2024] (cross-list from math-ph)
Spin-charge separation for paired Dirac fermions in $(1 + 1)$ dimensions
Laith H. Haddad🇺🇸
We study Dirac fermions at finite density coupled to a complex pairing field assumed to obey scalar field theory with quartic self-repulsion. The bulk of our work develops the mathematics that elucidates the propagation of fermionic excitations in such systems as independent spin (boosts) and charge (fermion number) degrees of freedom. A necessary ingredient is the presence of broken $U (1)$ symmetry in the pairing field and decoupling of its density and phase. In the fermion sector, these elements give rise to an emergent spin-dependent gauge coupling which binds in-vacuum spin and charge into elementary fermions, while driving proliferation of unbound spin and charge for finite condensation in the pairing field. Notably, the onset of spin-charge separation is signaled by $P T$ -symmetry breaking and decoupling of spin components under Lorentz transformations. Our investigation concludes with two theorems that identify generic features of spin-charge separation in such systems.
Comments:
14 pages, no figures
Subjects:
Mathematical Physics (math-ph); High Energy Physics — Theory (hep-th); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2409.04700 [pdf]
JHEP(2024)·1 citation
10
[Submitted on 7 Sept 2024] (cross-list from gr-qc)
Leptodermic corrections to the TOV equations and nuclear astrophysics within the effective surface approximation
A.G. Magner · S.P. Maydanyuk · A. Bonasera · H. Zheng · T. Depastas · A.I. Levon · U.V. Grygoriev
The macroscopic model for a neutron star (NS) as a liquid drop at the equilibrium is used to extend the Tolman-Oppenheimer-Volkoff (TOV) equations taking into account the gradient terms responsible for the system surface. The parameters of the Schwarzschild metric in the spherical case are found with these surface corrections to the known leading (zero) order of the leptodermic approximation $a / R << 1$ , where $a$ is the NS effective-surface (ES) thickness, and $R$ is the effective NS radius. The energy density $E$ is considered in a general form including the functions of the particle number density and of its gradient terms. The macroscopic gravitational component $Φ (ρ)$ of the energy density is taken into account in the simplest form as expansion in powers of $ρ - ρ$ , where $ρ$ is the saturation density, up to second order, in terms of its contributions to the separation particle energy and incompressibility. Density distributions $ρ$ across the NS ES in the normal direction to the ES, which are derived in the simple analytical form at the same leading approximation, was used for the derivation of the modified TOV (MTOV) equations by accounting for their NS surface corrections. The MTOV equations are analytically solved at first order and the results are compared with the standard TOV approach of the zero order.
Comments:
24 pages, 9 figures, 1 table. arXiv admin note: text overlap with arXiv:2403.01445
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2409.04745 [pdf]
NPA(2025)·2 citations
11
[Submitted on 7 Sept 2024] (cross-list from astro-ph.HE)
Formation of twin compact stars in low-mass X-ray binaries: Implications on eccentric and isolated millisecond pulsar populations
S. Chanlaridis · D. Ohse · D. E. Alvarez-Castillo · J. Antoniadis · D. Blaschke · V. Danchev · N. Langer · D. Misra
Millisecond pulsars (MSPs) are laboratories for stellar evolution, strong gravity, and ultra-dense matter. Although MSPs are thought to originate in low-mass X-ray binaries (LMXBs), approximately 27% lack a binary companion, and others are found in systems with large orbital eccentricities. Understanding how these systems form may provide insight into the internal properties of neutron stars (NSs). We studied the formation of a twin compact star through rapid first-order phase transitions in NS cores due to mass accretion in LMXBs. We investigated whether this mechanism, possibly coupled with secondary kick effects such as neutrino or electromagnetic rocket effects, leaves an observable long-lasting imprint on the orbit. We simulated mass accretion in LMXBs consisting of a NS and a low-mass main-sequence companion and followed the evolution of the NS mass, radius, and spin until a strong phase transition is triggered. For the NS structure, we assumed a multi-polytrope equation of state that allows for a sharp phase transition from hadronic to quark matter and satisfies observational constraints. We find that in compact binaries with relatively short pre-Roche lobe overflow orbital periods, an accretion-induced phase transition can occur during the LMXB phase. In contrast, in systems with wider orbits, this transition can take place during the spin-down phase, forming an eccentric binary MSP. If the transition is accompanied by a secondary kick, then the binary is likely to be disrupted, forming an isolated MSP or re-configured into an ultra-wide orbit. Our findings suggest that accretion in LMXBs provides a viable path for forming twin compact stars, potentially leaving an observable imprint on the orbit. The eccentricity distribution of binary MSPs with long orbital periods (> 50 d) could provide constraints on first-order phase transitions in dense nuclear matter.
Comments:
12 pages, 6 figures. Accepted in Astronomy & Astrophysics (A&A)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2409.04755 [pdf]
Astron.Astrophys.(2025)·11 citations
12
[Submitted on 7 Sept 2024] (cross-list from hep-ph)
Medium-induced parton splitting in expanding QCD matter
Ismail Soudi🇫🇮
Using the approach derived by Caron-Huot and Gale from the BDMPS-Z formalism, we obtain medium-induced parton splitting rates in a Bjorken expanding QCD matter. We compare the rate with the case of a static medium and investigate the impact of the medium expansion on the splitting rate. We also consider the leading order in the opacity expansion and the harmonic oscillator solution. These approximations are recovered in the limits of small and large formation times, respectively.
Comments:
8 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2409.04806 [pdf]
5 citations
13
[Submitted on 8 Sept 2024] (cross-list from hep-ph)
Heavy flavor-asymmetric pseudoscalar mesons on the light front
Chao Shi🇨🇳 · Pengfei Liu🇨🇳 · Yi-Lun Du🇨🇳 · Wenbao Jia🇨🇳
We extract the leading Fock-state light front wave functions (LF-LFWFs) of heavy flavor-asymmetric pseudoscalar mesons $D$ , $B$ and $B_{c}$ from their Bethe-Salpeter wave functions based on Dyson-Schwinger equations approach, and study their leading twist parton distribution amplitudes, generalized parton distribution functions and transverse momentum dependent parton distributions. The spatial distributions of the quark and antiquark on the transverse plane are given, along with their charge and energy distributions on the light front. We find that in the considered mesons, the heavier quarks carry most longitudinal momentum fraction and yield narrow $x$ -distributions, while the lighter quarks play an active role in shaping the transverse distributions within both spatial and momentum space, exhibiting a duality embodying characteristics from both light mesons and heavy quarkonium.
Comments:
10 pages,9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.05098 [pdf]
PRD(2024)·11 citations
14
[Submitted on 8 Sept 2024] (cross-list from hep-ph)
Relaxation time approximation revisited and non-analytical structure in retarded correlators
Jin Hu🇨🇳
In this paper, we give a rigorous mathematical justification for the relaxation time approximation (RTA) model. We find that only the RTA with an energy-independent relaxation time can be justified in the case of hard interactions. Accordingly, we propose an alternative approach to restore the collision invariance lacking in traditional RTA. Besides, we provide a general statement on the non-analytical structures in the retarded correlators within the kinetic description. For hard interactions, hydrodynamic poles are the long-lived modes. Whereas for soft interactions, commonly encountered in relativistic kinetic theory, the gapless eigenvalue spectrum of linearized collision operator leads to gapless branch-cuts. We note that particle mass and inhomogeneous perturbations would complicate the above-mentioned non-analytical structures.
Comments:
Version published in SciPost Physics. 12 pages, title changed. Any questions and comments are welcome
Subjects:
High Energy Physics — Phenomenology (hep-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2409.05131 [pdf]
SciPost Phys.(2026)·12 citations
15
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Strong decays of $a_{0}$ , $f_{0}$ , $f_{2}$ , and $K_{2}^{*}$ resonances as dynamically generated states of two vector mesons
Qing-Hua Shen🇨🇳 · Li-Sheng Geng🇨🇳 · Ju-Jun Xie🇨🇳
The two-body strong decays of the $f_{0} (1500)$ , $f_{0} (1710)$ , $a_{0} (1710)$ , $f_{2} (1270)$ , $f_{2}^{'} (1525)$ , and $K_{2}^{*} (1430)$ resonances are investigated, assuming them as dynamically generated states of two vector mesons via $s$ -wave interactions. The partial decay widths of all the possible two-body pseudoscalar meson-pseudoscalar meson final states are calculated considering the triangular diagrams. It is found that the ratios of branching fractions are similar to the previous results for most channels, which were obtained by using the real-axis method and considering the box diagrams. However, there are also differences. In addition, our focus is on the partial decay widths. More precise experimental measurements are needed to test the model calculations and determine the nature of these scalar and tensor mesons. It is anticipated that the BES\uppercase\expandafter{\romannumeral3}, Belle\uppercase\expandafter{\romannumeral2} and LHCb collaborations will conduct these measurements in the future.
Comments:
Published in Eur.Phys.J.A 61 (2025) 3, 42
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2409.05302 [pdf]
EPJA(2025)·5 citations
16
[Submitted on 9 Sept 2024] (cross-list from astro-ph.HE)
Confronting new NICER mass-radius measurements with phase transition in dense matter and twin compact stars
Jia Jie Li (SWU, Chongqing)🇨🇳 · Armen Sedrakian (FIAS, Frankfurt and U. Wroclaw)🇩🇪 · Mark Alford (Washington U., St. Louis)🇺🇸
The (re)analysis of data on the X-ray emitting pulsars PSR J0030+0451 and J0740+6620, as well as new results on PSR J0437-4715 and J1231-1411, are confronted with the predictions of the equation of state (EoS) models allowing for strong first-order phase transition for the mass-radius ( $M$ - $R$ ) diagram. We use models that are based on a covariant density functional (CDF) EoS for nucleonic matter at low densities and a quark matter EoS, parameterized by the speed of sound, at higher densities. To account for the variations in the ellipses for PSR J0030+0451 obtained from different analyses, we examined three scenarios to assess their consistency with our models, focusing particularly on the potential formation of twin stars. We found that in two scenarios, where the ellipses for PSR J0030+0451 and J0437-4715 with masses close to the canonical mass $\sim 1.4 M_{⊙}$ are significantly separated, our models allow for the presence of twin stars as a natural explanation for potential differences in the radii of these stars.
Comments:
v2, 12 pages, 4 figures, matches published version
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.05322 [pdf]
JCAP(2025)·21 citations
17
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Does nuclear medium affect the transverse momentum-dependent parton distributions of valence quark of pions?
Navpreet Kaur🇮🇳 · Satyajit Puhan🇮🇳 · Reetanshu Pandey🇮🇳 · Arvind Kumar🇮🇳 · Suneel Dutt🇮🇳 · Harleen Dahiya🇮🇳
We calculate the valence quark transverse momentum-dependent parton distributions (TMDs) of the lightest pseudoscalar meson, pions, in isospin asymmetric nuclear matter at zero temperature by employing a light-cone quark model. The medium modifications in the pion unpolarized TMDs are induced through the effective quark masses computed using the chiral SU( $3$ ) quark mean field model. The spin densities at different momentum fraction ( $x$ ) have also been calculated at different baryonic densities.
Comments:
7 pages and 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.05394 [pdf]
PLB(2024)·12 citations
18
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Probing strangeness with event topology classifiers in pp collisions at energies available at the CERN Large Hadron Collider with the rope hadronization mechanism in PYTHIA
Suraj Prasad🇮🇳 · Bhagyarathi Sahoo🇮🇳 · Sushanta Tripathy🇨🇭 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳
In relativistic heavy-ion collisions, the formation of a deconfined and thermalized state of partons, known as quark-gluon plasma (QGP), leads to enhanced production of strange hadrons in contrast to proton-proton (pp) collisions, which are taken as baseline. This observation is known as strangeness enhancement in heavy-ion collisions and is considered one of the important signatures that can signify the formation of QGP. However, in addition to strangeness enhancement, recent measurements hint at observing several heavy-ion-like features in high multiplicity pp collisions at energies available at the CERN Large Hadron Collider. Alternatively, event shape observables, such as transverse spherocity, transverse sphericity, charged particle flattenicity, and relative transverse activity classifiers, can fundamentally separate hard interaction-dominated jetty events from soft isotropic events. These features of event shape observables can probe the observed heavy-ion-like features in pp collisions with significantly reduced selection bias and can bring all collision systems on equal footing. In this article, we present an extensive summary of the strange particle ratios to pions as a function of different event classifiers using the PYTHIA~8 model with color reconnection and rope hadronization mechanisms to understand the microscopic origin of strangeness enhancement in pp collisions and also prescribe the applicability of these event classifiers in the context of strangeness enhancement. Charged particle flattenicity is found to be most suited for the study of strangeness enhancement, and it shows a quantitative enhancement similar to that seen for the analysis based on the number of multi-parton interactions.
Comments:
18 pages and 14 captioned figures. Same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2409.05454 [pdf]
PRC(2025)·14 citations
19
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Bound state basics
Paul Hoyer🇫🇮
Perturbative expansions for atoms in QED are developed around interacting states, typically defined by the Schrödinger equation. Calculations are nevertheless done using the standard Feynman diagram expansion around free states. The classical $- α / r$ potential is then obtained through an infinite sum of ladder diagrams. The complexity of this approach may have contributed to bound states being omitted from QFT textbooks, restricting the field to select experts. The confinement scale 1 fm of QCD must be introduced without changing the Lagrangian. This can be done via a boundary condition on the gauge field, which affects the bound state potential. The absence of confinement in Feynman diagrams may be due to the free field boundary condition. Poincaré invariance is realized dynamically for bound states, i.e., the interactions are frame dependent. Gauge theories have instantaneous interactions, due to gauge fixing at all points of space at the same time. In bound state perturbation theory each order must have exact Poincaré invariance. This is non-trivial even for atoms at lowest order. I summarize a perturbative approach to equal time bound states in QED and QCD, using a Fock expansion in temporal ( $A^{0} = 0$ ) gauge. The longitudinal electric field $E_{L}$ is instantaneous and need not vanish at spatial infinity for the constituents of color singlet states in QCD. Poincaré covariance determines the boundary condition for $E_{L}$ up to a universal scale, characterised by the gluon field energy density of the vacuum. A non-vanishing density contributes a linear term to the $q q ˉ$ potential, while $q q q, q q ˉ g$ and $g g$ color singlet states get analogous confining potentials.
Comments:
6 pages. Talk at the 42nd International Conference on High Energy Physics (ICHEP2024), 18-24 July 2024 in Prague, Czech Republic
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.05660 [pdf]
PoS(2025)·0 citations
20
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Exclusive vector-quarkonium photoproduction at NLO in alpha_s in collinear factorisation with evolution of the generalised parton distributions and high-energy resummation
C.A. Flett🇫🇷 · J.P. Lansberg🇫🇷 · S. Nabeebaccus🇫🇷 · M. Nefedov🇫🇷 · P. Sznajder🇵🇱 · J. Wagner🇵🇱
We perform the first complete one-loop study of exclusive photoproduction of vector quarkonia off protons in Collinear Factorisation (CF) including the scale evolution of the Generalised Parton Distributions (GPDs). We confirm the perturbative instability of the cross section at high photon-proton-collision energies (W_gamma+p) at Next-to-Leading Order (NLO) in alpha_s and solve this issue by resumming higher-order QCD corrections, which are enhanced by a logarithm of the parton energies, using High-Energy Factorisation (HEF) in the Doubly-Logarithmic Approximation (DLA) matched to CF. Our NLO CF + DLA HEF results are in agreement with the latest HERA data, show a smaller sensitivity to the factorisation and renormalisation scales compared to Born-order results. Quark-induced channels via interference with gluon ones are found to contribute at most 20% of the cross section for W_gamma+p > 100 GeV. Our results also show that such exclusive cross sections cannot be accurately obtained from the square of usual Parton Distribution Functions (PDFs) and clearly illustrate the importance of quarkonium exclusive photoproduction to advance our understanding of the 3D content of the nucleon in terms of gluons. Our work provides an important step towards a correct interpretation of present and future experimental data collected at HERA, the EIC, the LHC and future experiments.
Comments:
LaTeX, 10 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2409.05738 [pdf]
PLB(2024)·28 citations
21
[Submitted on 9 Sept 2024] (cross-list from hep-ph)
Asymptotically conformal CFL quark matter within a nonlocal chiral quark model
Oleksii Ivanytskyi🇵🇱
We propose a three-flavor nonlocal NJL model of quark matter with the scalar attractive, vector repulsive and diquark pairing interaction channels. The model is treated within the separable approximation to obtain the EoS of cold quark matter. The analysis of the high density asymptotics of the model allows us to conclude about its qualitative agreement with the perturbative QCD. Particularly, a color superconducting CFL state is found to be the ground one at high densities. The conformal limit of speed of sound and dimensionless interaction measure are also shown to be reached from below and above, respectively. The model is applied to modelling NSs within the scenario of early quark deconfinement triggered by the gravitational instability of the NS matter due to the BEC of a spin-color-flavor singlet three-diquark bound state, the light sexaquark, stable against the weak and strong decays. A conservative estimate of the sexaquark mass based on the most up-to-date results from QCD sum rules and a constituent quark model assumes an early quark deconfinement with the onset mass below $1 M_{⊙}$ . The scenario is shown to be consistent with the present observational constraints on the mass-radius relation and tidal deformability of NSs. Given the fact that the proposed model by construction exhibits an asymptotically conformal behavior, we consider the question about approximately conformal quark matter in NSs. We report a non-perturbative energy density range, which is inaccessible in NSs and where the speed of sound and dimensionless interaction measure of the CFL quark matter simultaneously attain the conformal values.
Comments:
Accepted for publication in Physical Review D, 16 pages, 4 figures, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.05859 [pdf]
PRD(2025)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE