Nuclear Theory·nucl-th

Thursday·March 27, 2025

12 papers—4 primary·8 cross-listed

05
[Submitted on 25 Mar 2025] (cross-list from hep-ph)
Exploiting $ν$ -dependence of projected energy correlators in HICs
Ankita Budhraja🇳🇱 · Balbeer Singh🇺🇸
We extend the recently derived factorization formula for energy-energy correlators to study the analytic structure of general $ν$ -point projected energy correlators in heavy ion collisions. The $ν$ -point projected energy correlators (or, $ν$ -correlators) are an analytically continued family of the integer $N$ -point projected energy correlators, which probe correlations between $N$ final-state particles. By tracking the largest separation ( $χ$ ) between the $N$ particles, in vacuum, their structure is closely related to the DGLAP splitting functions and exhibits a classical scaling behavior $\sim 1/ χ$ which is modified by resummation through the anomalous dimensions. We show that, in a thermal medium, the $ν$ -correlators display non-trivial angular scaling already at the leading order in perturbation theory. We find that for non-integer values, particularly $ν < 1$ , medium-induced jet function is enhanced compared to $ν > 1$ . This is particularly manifested in the ratios of $ν$ -correlators with respect to the two-point energy correlator which encode an intrinsic angular information for $ν < 1$ when compared to large $ν$ values. Moreover, for small- $ν$ values, the $ν$ -correlators appear to saturate at $ν = 0.01$ . We further confirm our leading-order numerical computations against simulated events from JEWEL for the parton level production cross-section. Finally, we qualitatively discuss the effect of BFKL resummation for various values of $ν$ .
Comments:
matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2503.20019 [pdf]
PLB(2026)·10 citations
06
[Submitted on 26 Mar 2025] (cross-list from hep-ph)
Nucleon Energy Correlators for the Odderon
Heikki Mäntysaari🇫🇮 · Yossathorn Tawabutr🇫🇮 · Xuan-Bo Tong🇫🇮
We investigate the T-odd nucleon energy correlator (NEC) at small $x$ and establish its connection with the spin-dependent odderon. Probing the T-odd NEC involves measuring a single transverse spin asymmetry (SSA) for the energy pattern in the target fragmentation region in deep inelastic scattering. We find that while the inclusive energy pattern results in a vanishing SSA, a nonzero SSA emerges when restricting the measurement to charged hadrons, which are directly measured in tracking detectors. To describe this effect, we introduce the track-based NEC and evaluate its small- $x$ limit from fracture functions using the energy sum rule. The resulting SSA exhibits an opposite sign between positively and negatively charged hadrons, providing a clear experimental signature of the odderon. Furthermore, by incorporating charge weighting into the NEC, we construct a C-odd tag in the final state, eliminating potential contamination from C-even gluonic contributions. Our results demonstrate that these track-based energy-pattern observables offer a clean and sensitive probe for unveiling odderon dynamics at the future electron-ion collider.
Comments:
17 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2503.20157 [pdf]
PRD(2025)·21 citations
07
[Submitted on 26 Mar 2025] (cross-list from hep-ph)
Proton Spin Decomposition via QCD Sum Rules
HyungJoo Kim🇯🇵 · Philipp Gubler🇯🇵 · Chihiro Sasaki🇯🇵
We present a novel approach for investigating the spin structure of hadrons based on the two-point function in quantum field theory. In a rotating frame, we derive two independent expressions of the two-point function and identify their equivalence, which allows for a complete decomposition of the total spin of a composite system into the angular momenta of its constituent particles. Applying this approach to the proton, we analyze its spin structure in the massless quark limit. Our results indicate that the quark spin contribution accounts for approximately 27 $%$ of the total proton spin at a low-energy scale, significantly deviating from the prediction of the non-relativistic quark model.
Comments:
5 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2503.20225 [pdf]
PLB(2025)·2 citations
08
[Submitted on 26 Mar 2025] (cross-list from hep-ph)
Effect of $α$ -clusters on particle production in O $-$ O and p $-$ O collisions at LHC energies
Deependra Sharma🇮🇳 · Arpit Singh🇮🇳 · Md. Samsul Islam🇮🇳 · Basanta Nandi🇮🇳 · Sadhana Dash🇮🇳
In the present work, O $-$ O collisions at $s_{N N}$ = 7 TeV and p $-$ O collisions at $s_{N N}$ = 9.9 TeV are studied using PYTHIA8/Angantyr model for heavy-ion collisions. The theoretically predicted $α$ -cluster structure of oxygen nucleus is implemented in the model to investigate the effect of initial configuration of oxygen nucleus on final state observables. The results obtained from $α$ -cluster structure are compared with those obtained from Woods-Saxon nuclear charge density distribution. The Angantyr model simulation showed that the radial distribution of oxygen nucleus in $α$ -cluster configuration is more compact in comparison to the Woods-Saxon distribution. The results on charged and identified particle pseudorapidity distribution is obtained in the two initial state configuration of the oxygen nucleus. The results demonstrated that the effect of initial geometrical configuration is more distinct in the non-central collisions in comparison to the central collisions for both O $-$ O and p $-$ O collisions.
Comments:
11 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2503.20339 [pdf]
PRC(2025)·9 citations
09
[Submitted on 26 Mar 2025] (cross-list from physics.plasm-ph)
Experimental Signatures for Identifying Distinct Origins of Color Field Generation
Subramanya Bhat K. N.🇮🇳 · Amita Das🇮🇳 · Bhooshan Paradkar🇮🇳 · V Ravishankar🇮🇳
Signatures for non-abelian dynamics have long been central to QCD and QGP. Equally important are they in spin systems and laser-plasma interactions, where they emerge as effective interactions. Distinguishing experimentally gauge inequivalent sources (and hence potentials) that produce the same field tensor is one major task in this endeavour. As a step in this direction, this paper investigates how physically distinct sources which produce the same color electric field (uniform and constant) may be distinguished experimentally in a gauge-invariant manner. We first study the motion of a test particle in such fields and show that the resultant trajectories are counterintuitive. We then examine the radiation emitted - both gluonic and photonic and show that each source (independent non-abelian configuration) leaves a unique signature in the energy spectra, laying the ground for application to specific physical systems.
Comments:
4 pages, 3 figures
Subjects:
Plasma Physics (physics.plasm-ph); cond-mat.other (cond-mat.other); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2503.20522 [pdf]
New J.Phys.(2025)·1 citation
10
[Submitted on 26 Mar 2025] (cross-list from hep-ph)
Chiral Solitons
Herbert Weigel🇿🇦
Generalizing quantum chromodynamics (QCD) from three to arbitrarily many color degrees of freedom suggests that baryons can be described as solitons in an effective meson theory whose interaction strength decreases with the number of colors. The exact form of that theory is unknown, but at low energies chiral symmetry and its breaking are considered as the construction recipes for modeling the theory. The Skyrmion is a static, localized solution in a non-linear field theory for pions and it is the most prominent version of a soliton in a chirally symmetric meson theory. Upon quantization it reproduces the spectrum of the low-lying baryons and their static properties reasonably well. Extending that theory by vector mesons improves on the agreement between predicted and empirical data. Chiral solitons within models for the quark flavor dynamics facilitate the investigation of nucleon structure functions. Here we provide a pedagogical overview of these facets.
Comments:
24 pages, invited contribution to the Encyclopedia of Particle Physics, v2: edited for proof corrections
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2503.20534 [pdf]
0 citations
11
[Submitted on 26 Mar 2025] (cross-list from hep-lat)
Quantum decoherence in the Caldeira-Leggett model by the real-time path integral on a computer
Jun Nishimura🇯🇵 · Hiromasa Watanabe🇯🇵
We propose first-principle calculations of an open system based on the real-time path integral formalism treating the environment as well as the system of our interest together on a computer. The sign problem that occurs in applying Monte Carlo methods can be overcome in general by using the so-called Lefschetz thimble method, which has been developed over the past decade. Here we focus on the Caldeira-Leggett model, which is well known, in particular, as a model of quantum decoherence. In this case, the calculation simplifies drastically since the path integral becomes Gaussian for typical initial conditions. The relevant saddle point, which is unique and complex, can be determined by solving a linear equation with a huge but sparse coefficient matrix, and the integration over the Lefschetz thimble can be performed analytically. Thus we obtain, without assumptions or approximations, the reduced density matrix after a long-time evolution, tracing out a large number of harmonic oscillators in the environment. In particular, we confirm the dependence of the decoherence time on the coupling constant and the temperature that has been predicted from the master equation in a certain parameter regime.
Comments:
38 pages, 19 figures, an affiliation added, minor revisions; the version accepted for publication in JHEP
Subjects:
High Energy Physics — Lattice (hep-lat); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2503.20699 [pdf]
JHEP(2025)·4 citations
12
[Submitted on 26 Mar 2025] (cross-list from hep-ph)
Feasibility of measuring the speed of sound of the quark-gluon plasma from the multiplicity and mean $p_{T}$ of ultracentral heavy-ion collisions
Lorenzo Gavassino🇺🇸 · Henry Hirvonen🇺🇸 · Jean-François Paquet🇺🇸 · Mayank Singh🇺🇸 · Gabriel Soares Rocha🇺🇸
The mean transverse momentum $⟨ p_{T} ⟩$ of hadrons has been observed experimentally and in numerical simulations to have a power-law dependence on the hadronic multiplicity $N$ in ultracentral relativistic heavy-ion collisions: $⟨ p_{T} ⟩ \propto N^{b_{UC}}$ . It has been put forward that this exponent $b_{UC}$ is the speed of sound of quark-gluon plasma measured at a temperature determined from $⟨ p_{T} ⟩$ . We study step by step the connection between (i) the energy and entropy of hydrodynamic simulations and (ii) experimentally measurable observables. We show that an argument based on energy and entropy should yield an exponent equal to the pressure over energy density $P / ε$ , rather than the speed of sound $c_{s}^{2}$ ; however, we also observe that $⟨ p_{T} ⟩$ and $N$ are not sufficiently accurate proxies for the energy and entropy to make this possible in practice. From simulations, we find that the exponent $b_{UC}$ is significantly different whether the ''effective volume'' is strictly constant or not, a condition that cannot be enforced experimentally. Additional tests using a modified equation of state find that the exponent $b_{UC}$ exhibits a variable degree of correlations with the speed of sound and with $P / ε$ , but is not an accurate measurement of either quantity in general.
Comments:
8 pages, 4 figures -- v4: version accepted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2503.20765 [pdf]
PRC(2025)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE