Nuclear Theory·nucl-th

Wednesday·March 12, 2025

9 papers—4 primary·5 cross-listed

05
Fingerprints of triaxiality in the charge radii of neutron-rich Ruthenium
Bernhard Maass🇺🇸 · Wouter Ryssens🇧🇪 · Michael Bender🇩🇪 · Daniel P. Burdette🇫🇷 · Jason Clark🇺🇸 · Adam Dockery🇺🇸 · Guilherme Grams🇺🇸 · Max Horst🇧🇪 · Phillip Imgram🇩🇪 · Kristian König🇩🇪 · Kei Minamisono🇺🇸 · Patrick Müller🇩🇪 and 10 other authors
We present the first measurements with a new collinear laser spectroscopy setup at the Argonne Tandem Linac Accelerator System utilizing its unique capability to deliver neutron-rich refractory metal isotopes produced by the spontaneous fission of 252Cf. We measured isotope shifts from optical spectra for nine radioactive ruthenium isotopes 106-114Ru, reaching deep into the mid-shell region. The extracted charge radii are in excellent agreement with predictions from the Brussels-Skyrme-on-a-Grid models that account for the triaxial deformation of nuclear ground states in this region. We show that triaxial deformation impacts charge radii in models that feature shell effects, in contrast to what could be concluded from a liquid drop analysis. This indicates that this exotic type of deformation should not be neglected in regions where it is known to occur, even if its presence cannot be unambiguously inferred through laser spectroscopy.
↳ nucl-exnucl-thPRL(2025)·6 citations
06
Suppressed Drell-Yan process by an external magnetic field
Shile Chen🇨🇳 · Jiaxing Zhao🇩🇪 · Pengfei Zhuang🇨🇳
The strongest electromagnetic fields in nature are created in high energy nuclear collisions and expected to change the dynamic scattering processes in the early stage. The magnetic field effect on the Drell-Yan process is investigated in this work. The single photon decay into quark pairs and lepton pairs in an external magnetic field leads to a significant Drell-Yan suppression in low and intermediate invariant mass region. The calculation up to the Landau level $n - 1$ is complete in the energy region $s < 2/3 n (e B)$ , and the enlarged phase space at higher landau levels may enhance the dilepton spectrum in the high mass region.
↳ hep-phnucl-thPLB(2025)·1 citation
07
Relativistic spin hydrodynamics from novel relaxation time approximation
Samapan Bhadury🇵🇱
With the help of a semi-classical kinetic theory, a new collision kernel is proposed, which simultaneously conserves the energy-momentum tensor and the spin tensor of a relativistic fluid of spin-1/2 particles irrespective of the frame and matching conditions, even when relaxation time is momentum dependent. The relativistic Boltzmann's equation is solved using this new collision kernel to obtain the expressions of the transport coefficients with general definitions for the frame and matching conditions. The results indicate the expected existence of Barnett-like effect and the non-existence of Einstein--de-Haas-like effects.
↳ hep-phhep-thnucl-thPRC(2025)·7 citations
08
Investigating the broadening phenomenon in two-particle correlations induced by gluon saturation
Kiera Cassar🇺🇸 · Zhen Wang🇨🇳 · Xiaoxuan Chu🇺🇸 · Elke-Caroline Aschenauer🇺🇸
It has been found that the gluon density inside the proton grows rapidly at small momentum fractions. Quantum Chromodynamics (QCD) predicts that this growth can be regulated by nonlinear effects, ultimately leading to gluon saturation. Within the color glass condensate framework, nonlinear QCD effects are predicted to suppress and broaden back-to-back angular correlations in collisions involving heavy nuclei. While suppression has been observed in various experiments in $d / p$ $+$ A collisions compared to $p$ $+$ $p$ collisions, the predicted broadening remains unobserved. This study investigates the contributions of intrinsic transverse momentum ( $k_{T}$ ), which is associated with saturation physics, as well as parton showers and transverse motion from fragmentation ( $p_{T}^{frag}$ ), which are not saturation dependent, to the width of the correlation function. Our findings show that the non-saturation dependent effects, especially the initial-state parton shower and $p_{T}^{frag}$ , which occur independently of the collision system, smear the back-to-back correlation more than gluon saturation does, making the broadening phenomenon difficult to observe.
↳ hep-phnucl-exnucl-thPRD(2025)·6 citations
09
Light-by-Light scattering in ultraperipheral heavy ion collisions: Estimating inelastic contributions
Mariola Klusek-Gawenda🇵🇱 · Victor P. Goncalves🇧🇷 · Antoni Szczurek🇵🇱
The current state-of-the-art theoretical estimations lead to cross-sections for $AA \to γ γ AA$ which are somewhat smaller than the measured ones by the ATLAS and CMS Collaborations, which motivates the searching and calculation of subleading corrections disregarded in these previous studies. In this paper, we estimate for the first time the contribution of inelastic channels to the Light-by-Light (LbL) scattering in ultraperipheral collisions of heavy ions (UPHICs), in which one or both of the incident nuclei dissociate ( $AA \to γ γ X Y$ where $X, Y = A, A^{'}$ ) due to the photon emission. These new mechanisms are related to extra emissions that are rather difficult to identify at the LHC and may be misinterpreted as enhanced $γ γ \to γ γ$ scattering compared to the Standard Model result. We include processes of coupling of photons to individual nucleons (protons and neutrons) in addition to coherent coupling to the whole nuclei (called standard approach here). Both elastic (nucleon in the ground state) and inelastic (nucleon in an excited state) in the couplings of photons to nucleons are taken into account. The inelastic nucleon fluxes are calculated using CT18qed photon in nucleon PDFs. The inelastic photon fluxes are shown and compared to standard photon fluxes in the nucleus. In addition, we show the ratio of the inelastic corrections to the standard contribution as a function of diphoton invariant mass and photon rapidity difference. We find that for the ATLAS acceptance region the inelastic corrections grow with $M_{γ γ}$ and rapidity difference. Our results indicate that the inelastic contributions can be of the order of 20-40 \% of the traditional (no nuclear excitation) predictions. Uncertainties due to factorization scale choice are quantified.
↳ hep-phnucl-thPLB(2025)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Fingerprints of triaxiality in the charge radii of neutron-rich Ruthenium

Suppressed Drell-Yan process by an external magnetic field

Relativistic spin hydrodynamics from novel relaxation time approximation

Investigating the broadening phenomenon in two-particle correlations induced by gluon saturation

Light-by-Light scattering in ultraperipheral heavy ion collisions: Estimating inelastic contributions

Affiliations