Thu·Sep 11, 2025Thursday·September 11, 2025

1. 01*

   Measurement of D${}^0$ meson photoproduction in ultraperipheral heavy ion collisions

   CMS Collaboration

   This Letter reports the first measurement of photonuclear D${}^0$ meson production in ultraperipheral heavy ion collisions. The study is performed using lead-lead collision data, with an integrated luminosity of 1.34 nb${}^{-1}$, collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.36 TeV. Photonuclear events, where one of the colliding nuclei breaks up and the other remains intact, are selected based on breakup neutron emissions and by requiring no particle activity in a large rapidity interval in the direction of the photon-emitting nucleus. The D${}^0$ mesons are reconstructed via the D${}^0$ $\to$ K${}^{-}$${\pi }^{+}$ decay channel, with the cross section measured as a function of D${}^0$ meson transverse momentum and rapidity. The results are compared with next-to-leading-order perturbative QCD calculations that employ recent parametrizations of the lead nuclear parton distribution functions, as well as with predictions based on the color glass condensate framework. This measurement is the first photonuclear collision study characterizing parton distribution functions of lead nuclei for parton fractional momenta $x$ (relative to the nucleon) ranging approximately from a few 10${}^{-4}$ to 10${}^{-2}$ for different hard energy scale $Q^2$ selections.

   nucl-exhep-exPRL(2026)·17 citations
2. 02*

   Wave-Breaking Phenomena in Quark-Gluon Plasma

   Biswarup Paul🇮🇳

   We investigate the onset of wave-breaking in the quark-gluon plasma (QGP) formed in heavy-ion collisions at both RHIC and the LHC. A nonlinear longitudinal color field is coupled to a three-dimensional viscous hydrodynamic background constrained by experimental conditions: Pb-Pb at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV (LHC) and Au-Au at $\sqrt{s_{\mathrm{NN}}}=200$ GeV (RHIC). The instantaneous wave-breaking threshold is determined from the in-medium plasma frequency, while the field evolution follows a nonlinear Landau equation with Debye screening and expansion damping. At the LHC, the higher initial temperature and density drive the system above the threshold within $\tau \lesssim$ 2.3 fm/$c$, whereas at RHIC the cooler and more dilute medium delays wave-breaking to $\tau \simeq 2.8$~fm/$c$. Scans over initial temperature, density, thermalization time, QGP lifetime, and collision system (RHIC vs LHC) confirm the robustness of this instability against parameter variations. These results identify wave-breaking as a universal microscopic mechanism for the early loss of coherence and rapid onset of hydrodynamics in the QGP, providing a common explanation for the fast equilibration observed at both RHIC and the LHC.

   ↳ nucl-thhep-phnucl-ex0 citations
3. 03*

   A comprehensive view of nuclear shapes, rotations and vibrations from fully quantum mechanical perspectives

   Takaharu Otsuka🇯🇵

   The nuclear quadrupole collective states at low excitation energies are described in a novel, fully quantum mechanical and systematic manner as compared to traditional pictures initiated by Aage Bohr. The ellipsoidal shapes are shown to be triaxial in virtually all strongly deformed nuclei, in contrast to the Ansatz of axially symmetric shapes. The rotational bands of such triaxially deformed nuclei are described in a fully quantum mechanical way, i. e., without resorting to quantized free rotation of rigid body. The excitation energies within a rotational band, exhibiting the $J(J+1)$ dependence on angular momentum $J$, are shown to basically represent the change of binding energies due to nuclear forces. This differs from the interpretation á la Aage Bohr as rotational kinetic energies. The $K$ quantum numbers are shown to be practically conserved for triaxial ellipsoids, which turned out to be a real but positive surprise to many people in the field. The so-called $\gamma$ bands are shown to be $K$=2${}^{+}$ rotations rather than $\gamma$-vibrations, leading to a nice description of the so-called $\gamma \gamma$ 4${}^{+}$ state as a $K$=4${}^{+}$ rotation. Vibrational modes are also shown to emerge in this study. Thus, the whole picture of low-energy quadrupole collective motion of heavy nuclei has been renewed in a fully quantum mechanical fashion, which differs from the traditional picture but appears to be simpler and more natural.

   ↳ nucl-thnucl-exEPJ Web Conf.(2025)·3 citations
4. 04*

   Enhanced water Cherenkov detector for soil moisture detection

   J. Betancourt · C. Sarmiento-Cano · I. Sidelnik · H. Asorey · Y. Domínguez-Ballesteros · L. Miranda-Leuro · Luis A. Núñez🇨🇴

   This work evaluates the ability of a water Cherenkov detector to measure thermal neutrons and explores its application to soil-moisture monitoring. We study a NaCl-doped detector and model its response to (i) monochromatic thermal neutrons and (ii) the natural thermal-neutron flux expected from dry soil at the elevation of Bucaramanga, Colombia. The ambient flux is estimated with the ARTI framework, and the detector response is simulated with MEIGA in Geant4. Doping with NaCl introduces additional capture channels on ${}^{35,37}\mathrm{Cl}$ and ${}^{23}\mathrm{Na}$; in particular, ${}^{35}\mathrm{Cl}$ has a thermal-neutron absorption cross section up to two orders of magnitude larger than hydrogen, boosting the capture signal. Our results indicate that water Cherenkov detectors can detect thermal neutrons with practical sensitivity under field conditions, enabling their integration into precision agriculture networks for soil moisture sensing. More broadly, this approach extends the cosmic-ray detection range of Cherenkov detectors using non-toxic, low-cost materials.

   ↳ physics.ins-detastro-ph.HEastro-ph.IMhep-ex+12 citations
5. 05*

   Lattice calculation of the Sn isotopes near the proton dripline

   Fabian Hildenbrand🇩🇪 · Serdar Elhatisari🇹🇷 · Ulf-G. Meißner🇩🇪 · Helen Meyer🇩🇪 · Zhengxue Ren🇩🇪 · Andreas Herten🇩🇪 · Mathis Bode🇩🇪

   We present the first $\text{ab initio}$ lattice calculations of the proton-rich tin isotopes ${}^{99}$Sn to ${}^{102}$Sn using nuclear lattice effective field theory with high-fidelity two- and three-nucleon forces. For a given set of three-nucleon couplings, we reproduce binding energies with $\sim 1\%$ accuracy for the even-even systems, and obtain energy splitting and two-nucleon separation energies in agreement with experiment. Our results confirm the $N=50$ shell closure and reveal that the binding energy of ${}^{99}$Sn lies below values extrapolated from heavier isotopes.

   ↳ nucl-thhep-lathep-phnucl-exPRL(2026)·13 citations
6. 06*

   Constraining the Resolution Length of Quark-Gluon Plasma with New Jet Substructure Measurements

   Arjun Srinivasan Kudinoor🇺🇸 · Daniel Pablos🇪🇸 · Krishna Rajagopal🇺🇸

   We show that recent measurements of substructure-dependent jet suppression constrain the value of the resolution length of the droplets of quark-gluon plasma (QGP) formed in heavy ion collisions. This resolution length, $L_{\mathrm{res}}$, is defined such that the medium can only resolve partons within a jet shower that are separated by more than $L_{\mathrm{res}}$. We first use Hybrid Model calculations to reproduce ALICE measurements of the scaled Soft Drop angle ${\theta }_g$ for anti-$k_t$ $R=0.2$ jets reconstructed from charged-particle tracks. We find that the narrowing of the ${\theta }_g$-distribution in PbPb collisions compared to pp collisions that is seen in the ALICE data rules out a picture of fully coherent energy loss ($L_{\mathrm{res}}=\infty$) where each entire parton shower loses energy to the plasma as if it were a single unresolved colored object. We then use Hybrid Model calculations to reproduce ATLAS measurements of $d{R}_{12}$, the Soft Drop angle obtained by applying the Soft Drop grooming procedure to all charged-particle tracks in $R=1$ jets reconstructed from $R=0.2$ skinny subjets. Our analysis demonstrates that the ATLAS measurements of $R_{\mathrm{AA}}$ for such $R=1$ jets as a function of $d{R}_{12}$ are inconsistent with a picture of fully incoherent energy loss ($L_{\mathrm{res}}=0$) in which every splitting in a parton shower is immediately resolved by the plasma. We find that our Hybrid Model calculations agree best with the ATLAS measurements if QGP has a finite, nonzero, resolution length $L_{\mathrm{res}}\sim (1-2)/(\pi T)$. For the first time, jet substructure measurements are constraining the resolution length of QGP from below, as well as from above.

   ↳ hep-phnucl-exnucl-th6 citations
7. 07*

   Data-driven method to estimate contamination from light ion beam transmutation at colliders

   Sruthy Jyothi Das🇺🇸 · Austin Baty🇺🇸

   Collisions of relativistic light ions, such as oxygen, neon, and magnesium, have been proposed as a way to examine the system-size dependence of dynamics typically associated with the quark-gluon plasma produced in collisions of heavier ions such as xenon, gold, or lead. Recent efforts at both the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) have produced large datasets of proton-oxygen, oxygen-oxygen, and neon-neon collisions, catalyzing intense interest in experimental backgrounds associated with light-ion collisions. In particular, electromagnetic dissociation of light ions while they are circulating in a collider can result in beam contamination that is difficult to simulate precisely. Here we propose a data-driven method for evaluating the potential impact of beam contaminants on physics analyses. The method exploits the time dependence and smaller size of contaminant ion species to define control regions that can be used to quantify potential contamination effects. A simple model is used to illustrate the method and to study its robustness. This method can inform studies of recent LHC and RHIC data and could also be useful for future light-ion programs at the LHC and beyond.

   ↳ physics.acc-phnucl-exPRC(2026)·6 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.