Nuclear Theory·nucl-th

Monday·December 1, 2025

19 papers—7 primary·12 cross-listed

08
[Submitted on 26 Nov 2025] (cross-list from nucl-ex)
Wavelet analysis of monopole strength in highly deformed $^{24}$ Mg
A. Bahini🇿🇦 · V. O. Nesterenko🇷🇺 · P. von Neumann-Cosel🇩🇪 · P.-G. Reinhard🇩🇪 · J. Carter🇿🇦 · N. A. Ashurko🇷🇺 · R. Neveling🇿🇦 · A. Repko🇸🇰 · I. T. Usman🇿🇦
Experimental data on $α$ -particle inelastic scattering for monopole excitations in $^{24}$ Mg in the excitation-energy region $E_{x}$ $=$ $9$ $-$ $25$ MeV, obtained at the iThemba Laboratory for Accelerator Based Sciences (iThemba LABS), have been analyzed within a fully self-consistent quasiparticle random-phase approximation (QRPA) framework using two Skyrme parametrizations. A good overall agreement with the experimental data is achieved, particularly with the SkP $^{δ}$ force, which corresponds to a low nuclear incompressibility of $K_{\infty}$ $=$ $202$ MeV. Extraction of energy scales, by means of wavelet analysis, characterizing the observed fine structure of the isoscalar giant monopole resonance (ISGMR) as well as the low-energy region $10$ $-$ $18$ MeV of the deformation-induced monopole-quadrupole coupling (MQC) in order to investigate the damping mechanism contributing to their decay widths. Characteristic energy scales are extracted from the fine structure using continuous wavelet transforms. The experimental results are compared to QRPA calculations employing the Skyrme parameterizations SkP $^{δ}$ and SVbas. A significant, if not decisive, impact of the MQC strength on the wavelet power spectra is observed across the entire excitation-energy range of $10$ $-$ $24$ MeV. Wavelet features derived from the QRPA and from unperturbed two-quasiparticle (2qp) monopole strengths are compared. The results demonstrate that the residual interaction plays a key role in reproducing realistic wavelet powers and characteristic energy scales. Overall, a continuous range of scales $δ E$ $=$ $200$ $-$ $1000$ keV is obtained rather than distinct isolated scales. The deformation softness of $^{24}$ Mg is found to significantly influence both the monopole strength distribution and the wavelet characteristics.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2511.21880 [pdf]
PRC(2026)·0 citations
09
[Submitted on 26 Nov 2025] (cross-list from hep-ph)
Energy-momentum tensor form factor D(t) of proton and neutron
Andrea Mejia🇺🇸 · Peter Schweitzer🇺🇸
The energy-momentum tensor (EMT) form factor $D (t)$ is finite and negative in hadronic models and lattice QCD when only strong forces are included. However, when electromagnetic forces are considered, the $D (t)$ of charged hadrons undergoes a dramatic change: at small $t$ , it changes sign and diverges like $1/ - t$ as shown for the proton in the classical model by Białynicki-Birula based on residual nuclear forces which can be understood as a mean field approach. We construct an analogous neutron model and show that this framework accurately explains the electromagnetic proton-neutron mass difference. We demonstrate that, after appropriately rescaling the residual nuclear forces, the model can reproduce lattice data on the nucleon $D (t)$ up to $(- t) ≲ 1$ GeV $^{2}$ as well as QED effects. Based on this realistic model description, we show that the proton and neutron $D (t)$ form factors are practically indistinguishable down to $(- t) \approx 1 0^{- 4} Ge V^{2}$ far below what can currently be accessed experimentally. We conclude that in the foreseeable future the $D (t)$ form factors of proton and neutron will practically look the same in experiments and phenomenology.
Comments:
14 pages, 4 figures, typos fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2511.21916 [pdf]
PRD(2026)·4 citations
10
[Submitted on 27 Nov 2025] (cross-list from hep-ph)
QCD axions and domain walls in dense matter under compact stellar conditions
Zhen-Yan Lu🇨🇳 · Shu-Peng Wang🇨🇳 · Qi Lu🇨🇳 · Bo-Nan Zhang🇨🇳 · Marco Ruggieri🇮🇹
In compact stellar environments, the stability of dense QCD matter requires the simultaneous fulfillment of charge neutrality and beta equilibrium. In this work, we study how temperature and finite chemical potential affect QCD topology and axion properties within this medium, analyzing both cases with and without the charge neutrality condition. Our results show that the topological susceptibility and axion properties are highly sensitive to the critical behavior of the chiral phase transition in both cases. In particular, the axion mass is strongly suppressed near the transition, while the axion self-coupling constant develops a pronounced peak whose magnitude depends on the temperature and density of the medium. Remarkably, around the critical point at $T ≃ 70$ MeV and $μ ≃ 346$ MeV, the self-coupling constant is enhanced by more than a factor of seven compared to its vacuum value, a feature that to the best of our knowledge has not been reported in previous studies. Such a strong amplification at the phase boundary indicates that axion-mediated interactions could play an important role in shaping the structure and stability of compact stars, with potential implications for their evolution and observable astrophysical signatures.
Comments:
9 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2511.21995 [pdf]
EPJC(2025)·2 citations
11
[Submitted on 27 Nov 2025] (cross-list from nucl-ex)
Does the suppression shown at LHC in O-O collisions follow the systematics obtained for A-A collisions ?
M.Petrovici🇷🇴 · A.Pop🇷🇴
In this paper we present to what extent recent experimental results obtained for $π^{0}$ suppression in O-O collisions at $s_{N N}$ =5.36 TeV fit into the systematics for much heavier systems. The systematics with which the comparison is made was published a few years ago \cite{Pet_1} in terms of charged particles suppression $R_{AA}$ as a function of $⟨ N_{p a r t} ⟩$ and $⟨ d N_{c h} / d η ⟩$ . The values of $R_{AA}$ at $⟨ d N_{c h} / d η ⟩$ and $⟨ N_{p a r t} ⟩$ experimentally measured and estimated by Glauber MC, respectively, for O-O collisions are in good agreement with the systematics obtained for A-A collisions.
Comments:
3 pages, 4 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2511.22139 [pdf]
0 citations
12
[Submitted on 27 Nov 2025] (cross-list from hep-ph)
Topological production of charmonia with event-shape engineering in $pp$ collisions at $s = 13$ TeV using PYTHIA8
Aswathy Menon Kavumpadikkal Radhakrishnan🇮🇳 · Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳
The production of heavy quarks (charm and beauty) in high-energy hadronic and nuclear collisions provides an excellent testing ground for the theory of strong interactions and validates models based on quantum chromodynamics (QCD). In this work, prompt and nonprompt production of $J/ ψ$ in $pp$ collisions at $s = 13$ TeV are studied as a function of transverse spherocity using PYTHIA8. $J/ ψ$ is reconstructed via its electromagnetic decay to dielectrons and dimuons, in mid- and forward-rapidity, respectively. Transverse spherocity, an event shape observable, is used to distinguish hard QCD events from the softer, isotropic ones. In PYTHIA8, the production of $J/ ψ$ can be influenced by the average number of multiple parton interactions ( $⟨ N_{mpi} ⟩$ ), owing to the underlying events (UE), which have a dominant contribution to particle production at lower transverse momentum. Since transverse spherocity is correlated to $⟨ N_{mpi} ⟩$ , this can serve as an experimentally accessible tool for event selection to study the underlying QCD processes influencing the prompt and nonprompt $J/ ψ$ production. This study reveals the correlation between heavy-flavor production dynamics and topological event selection in $pp$ collisions using PYTHIA8, whose relevance awaits experimental validation.
Comments:
Same as the published version in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2511.22190 [pdf]
PRD(2026)·1 citation
13
[Submitted on 27 Nov 2025] (cross-list from physics.atom-ph)
Relativistic recoil as a key to the fine-structure puzzle in muonic $^{90} Zr$
Konstantin A. Beyer🇩🇪 · Igor A. Valuev🇩🇪 · Zoia A. Mandrykina🇩🇪 · Zewen Sun🇩🇪 · Natalia S. Oreshkina🇩🇪
The long-standing fine-structure anomaly in muonic $^{90}$ Zr is resolved through a rigorous treatment of the relativistic-recoil effect. From a fit of ab initio QED calculations of the muonic $^{90}$ Zr spectrum to precision measurements performed four decades ago, we extract a significantly more precise root-mean-square (rms) charge radius with 6-fold improvement in quality of the fit. A 2-parameter Fermi (2pF) distribution is assumed to model the nuclear charge density and yields a best-fit value of rms charge radius of $r_{rms} [^{90} Zr] = 4.2732 (7)$ fm ( $χ^{2} / DoF = 0.995$ ), in agreement with the previous muonic spectroscopy value, but a factor $6$ more precise, and 3 $σ$ larger than the accepted literature value. Additionally, the same analysis has been performed for $^{120}$ Sn, where the extracted value of $r_{rms} [^{120} Sn] = 4.6518 (34)$ fm ( $χ^{2} / DoF = 0.88$ ) is consistent with the accepted value. These results confirm our assumption that the muonic fine-structure puzzle arose from an incomplete treatment of QED effects and their uncertainties.
Comments:
8 pages, 4 figures
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2511.22298 [pdf]
9 citations
14
[Submitted on 27 Nov 2025] (cross-list from quant-ph)
On the possibility of superradiant neutrino emission by atomic condensates
Massimo Blasone🇮🇹 · Loredana Gastaldo🇩🇪 · Francesco Romeo🇮🇹
In a recent work [B. J. P. Jones and J. A. Formaggio, Phys. Rev. Lett. 135, 111801 (2025)], the possibility of superradiant neutrino emission from atomic condensates has been theoretically proposed. Subsequent analysis by Y. K. Lu, H. Lin, and W. Ketterle [arXiv:2510.21705] questioned this scenario, emphasizing the limiting role of the fermionic nature of the decayed atoms. In this study, we revisit the problem and discuss under which conditions collective emission phenomena might still emerge in cold-atom systems.
Comments:
10 pages, 5 figures
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2511.22450 [pdf]
PRD(2026)·1 citation
15
[Submitted on 27 Nov 2025] (cross-list from hep-ph)
New Physics Searches via Beam Normal Spin Asymmetry in Bhabha Scattering
Aleksandr Pustyntsev🇩🇪 · Muthubharathi S. Ramasamy🇩🇪 · Marc Vanderhaeghen🇩🇪
We examine the sensitivity of the beam normal spin asymmetry in Bhabha scattering to beyond the Standard Model (BSM) mediators, in the context of the JLab polarized positron program. A key property of this observable is that the Standard Model contribution exhibits a zero crossing at a fixed scattering angle, providing a clean, effectively background-free point for these searches. We consider scalar, vector, and axial vector mediators and present projected bounds, finding that scalar and vector scenarios allow a significant extension of the search ranges beyond existing constraints.
Comments:
5 pages, 3 figures; v2: matches the version published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2511.22568 [pdf]
PRD(2026)·2 citations
16
[Submitted on 27 Nov 2025] (cross-list from hep-ph)
Short-range production of three bottom mesons
Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪
Previous investigations of the three-body dynamics of $B$ mesons have shown that no Efimov effect arises in systems composed of three $B$ and $B^{*}$ mesons. This implies that the properties of such three-body systems can be described reliably within nonrelativistic effective field theory (NREFT) with short-range interactions using only two-body input, as three-body forces are strongly suppressed. In this work, we present leading-order predictions for the three-body point production rates of systems consisting of three $B$ and $B^{*}$ mesons. These predictions provide a novel way to experimentally probe the $B^{(*)}$ - $B ˉ^{(*)}$ interactions, which play a crucial role in the hadronic-molecule interpretation of the $T_{b b ˉ 1} (10610)$ and $T_{b b ˉ 1} (10650)$ states. Moreover, they provide a way to test the approximate conformal symmetry predicted for such systems at low energies experimentally.
Comments:
26 pages, 11 figures; updated to the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2511.22590 [pdf]
JHEP(2026)·1 citation
17
[Submitted on 27 Nov 2025] (cross-list from hep-ph)
Saturation effects in exclusive vector meson production in DIS
Oscar Garcia-Montero🇩🇪 · Yannik Hoffmann🇩🇪 · Sören Schlichting🇩🇪
We investigate saturation effects in exclusive vector meson production in deep inelastic scattering (DIS), where we model fluctuations within the target protons as localized color-charge hotspots. Based on the Color Glass Condensate (CGC) framework and the dipole picture for vector meson production, we examine the dependencies of coherent and incoherent scattering cross sections on the momentum transfer. We draw conclusions on the effectiveness of our hot spot model and the strength of the suppression of the scattering cross sections caused by saturation effects. We find that saturation has mild effects in the given energy and charge-density ranges, but can also show that suppression becomes more prominent as the color-charge density inside the proton increases.
Comments:
17 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2511.22763 [pdf]
1 citation
18
[Submitted on 28 Nov 2025] (cross-list from hep-lat)
Speed of sound exceeding the conformal bound in dense QCD-like theories
Etsuko Itou🇯🇵 · Kei Iida🇯🇵 · Kotaro Murakami🇯🇵 · Daiki Suenaga🇯🇵
We investigated the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures using the lattice Monte Carlo simulations. A rich phase structure below the pseudo-critical temperature $T_{c}$ as a function of quark chemical potential has been revealed. In a high-density regime, we can see a superfluid phase, where the diquark condensate takes a non-zero expectation value. We have newly found that the speed of sound exceeds the conformal bound, which is the value of the relativistic free theory. This talk is based on Refs.~\cite{Iida:2022hyy, Iida:2024irv, Itou:2025vcy}.
Comments:
5pages, Proceedings of the 29th International Nuclear Physics Conference (INPC2025), Deajon, Korea, May 25-30, 2025
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2511.22878 [pdf]
EPJ Web Conf.(2026)·0 citations
19
[Submitted on 28 Nov 2025] (cross-list from hep-ph)
Analytical Soft Functions for Heavy-Quark Final States at Hadron Colliders
Ze Long Liu🇨🇳 · Pier Francesco Monni🇨🇭
We present the first computation of the complete two-loop, fully-differential soft function describing the production of a heavy-quark pair in association with a color-singlet system at hadron colliders. This result constitutes one of the most complex soft functions known to date and it is obtained in closed analytic form for generic multi-dimensional kinematics. This allows us to obtain novel analytic results for the transverse-momentum-dependent and threshold soft functions in this class of processes. We further obtain a decomposition of the soft function into dipole and tripole color correlators, thereby supplying essential building blocks for processes involving a heavy-quark pair produced together with additional light jets at both hadron and lepton colliders. These results represent a key ingredient for advancing precision predictions for heavy-quark physics at the LHC.
Comments:
5 pages, 1 figure, ancillary files in https://doi.org/10.5281/zenodo.17739950
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2511.23280 [pdf]
PRL(2026)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE