Wed·Mar 5, 2025Wednesday·March 5, 2025

1. 01*

   Observation of the charged-particle multiplicity dependence of ${\sigma }_{\psi (2S)}/{\sigma }_{\text{J}/\psi }$ in pPb collisions at 8.16 TeV

   CMS Collaboration

   Bound states of charm and anticharm quarks, known as charmonia, have a rich spectroscopic structure that can be used to probe the dynamics of hadron production in high-energy hadron collisions. Here, the cross section ratio of excited ($\psi$(2S)) and ground state (J/$\psi$) vector mesons is measured as a function of the charged-particle multiplicity in proton-lead (pPb) collisions at a center-of-mass (CM) energy per nucleon pair of 8.16 TeV. The data corresponding to an integrated luminosity of 175 nb${}^{-1}$ were collected using the CMS detector. The ratio is measured separately for prompt and nonprompt charmonia in the transverse momentum range 6.5 $<$ $p_{\text{T}}$ $<$ 30 GeV and in four rapidity ranges spanning $-$2.865 $<$ $y_{\text{CM}}$ $<$ 1.935. For the first time, a statistically significant multiplicity dependence of the prompt cross section ratio is observed in proton-nucleus collisions. There is no clear rapidity dependence in the ratio. The prompt measurements are compared with a theoretical model which includes interactions with nearby particles during the evolution of the system. These results provide additional constraints on hadronization models of heavy quarks in nuclear collisions.

   nucl-exhep-exPRL(2025)·12 citations
2. 02*

   Momentum Flow Mechanisms and Color-Lorentz Forces on Quarks in the Nucleon

   Xiangdong Ji🇺🇸 · Chen Yang🇺🇸

   Momentum conservation in the nucleon is examined in terms of continuous flow of the momentum current density (or in short, momentum flow), which receives contributions from both kinetic motion and interacting forces involving quarks and gluons. While quarks conduct momentum flow through their kinetic motion and the gluon scalar (anomaly) contributes via pure interactions, the gluon stress tensor has both effects. The quarks momentum flow encodes the information of the color-Lorentz force density on them, and the momentum conservation allows to trace its origin to the gluon tensor and anomaly (a ``negative pressure'' potential). From the state-of-the-art lattice calculations and experimental fits on the form factors of the QCD energy-momentum tensor, we exhibit pictures of the momentum flow and the color-Lorentz forces on the quarks in the nucleon. In particular, the anomaly contributes a critical attractive force with a strength similar to that of a heavy-quark confinement potential.

   ↳ hep-phhep-latnucl-exnucl-thResearch(2026)·23 citations
3. 03*

   Timelike Compton scattering on a spin-0 target with kinematic twist-4 precision

   V. Martinez-Fernandez🇫🇷 · B. Pire🇫🇷 · P. Sznajder🇵🇱 · J. Wagner🇵🇱

   We calculate the kinematic twist-3 and 4 corrections to the leading order amplitude of timelike Compton scattering (TCS) on a (pseudo-)scalar target, in the recently developed framework based on the conformal operator-product expansion. This allows us to compute the complete set of helicity amplitudes of the process, in particular those that vanish at leading twist. We compare the effects of higher twist contributions to TCS with those in deeply virtual Compton scattering (DVCS). Our estimates, based on a $\pi$-meson GPD model, indicate that these contributions are sizeable and will play a crucial role in the interpretation of data from current and forthcoming experiments.

   ↳ hep-phhep-exhep-thnucl-exPRD(2025)·10 citations
4. 04*

   Prospects for Pentaquark Baryon Search with the Upgraded LEPS2 Facility

   T. Nakano🇯🇵 · S. Ajimura🇯🇵 · Y. Asano🇯🇵 · S. Dat'e🇯🇵 · T. Hashimoto🇯🇵 · A. Higashi🇯🇵 · T. Hotta🇯🇵 · T. Ishikawa🇯🇵 · H. Katsuragawa🇯🇵 · R. Kobayakawa🇯🇵 · H. Kohri🇯🇵 · K. Mizutani🇯🇵 and 24 other authors

   We present prospects for the ${\Theta }^{+}$ pentaquark baryon search using the newly constructed LEPS2 facility at SPring-8. The LEPS2 detector system features significant improvements in acceptance for multi-particle final states compared to previous experiments. Our search employs two complementary strategies: direct production in the $\gamma n\to K^{-}{\Theta }^{+}$ reaction using a liquid deuterium target with a photon beam up to 2.4 GeV, and ${\bar{K}}^{\ast 0}$-associated ${\Theta }^{+}$ production using a liquid hydrogen target with a photon beam up to 2.9 GeV. The extended acceptance covers both forward and large angle regions, effectively spanning the kinematic regions explored by previous LEPS and CLAS experiments. The large acceptance and improved resolution of LEPS2, combined with these complementary approaches, provide unprecedented sensitivity for establishing the existence of the ${\Theta }^{+}$ or placing definitive upper limits on its production.

   ↳ hep-exnucl-exActa Phys.Polon.B(2025)·1 citation
5. 05*

   Automatic optimisation of a Parallel-Plate Avalanche Counter with Optical Readout

   María Pereira Martínez🇪🇸 · Xabier Cid Vidal🇪🇸 · Pietro Vischia🇪🇸

   An automatic optimisation procedure is proposed for some operational parameters of a Parallel-Plate Avalanche Counter with Optical Readout, a detector designed for heavy-ion tracking and imaging. Exploiting differentiable programming and automatic differentiation, we model the reconstruction of the position of impinging 5.5 MeV alpha particles for different detector configurations and build an optimisation cycle that minimizes an objective function. We analyse the performance improvement using this method, exploring the potential of these techniques in detector design.

   ↳ physics.ins-detnucl-exParticles(2025)·1 citation
6. 06*

   The Electron-Ion Collider as A Prospective Facility for Pentaquark Measurements

   In Woo Park🇰🇷 · Sungtae Cho🇰🇷 · Yongsun Kim🇰🇷 · Su Houng Lee🇰🇷

   The Electron-Ion Collider provides a groundbreaking opportunity to study heavy pentaquarks with unprecedented precision, leveraging its high collision energy and beam spin polarization capabilities. As a representative case, we analyze electroproduction cross sections of Pc (4312) under different spin-parity hypotheses using the vector meson dominance model. To ensure a parameter-free approach and minimize ambiguity, we incorporate results from the LHCb and GlueX experiments. To characterize the spin and the parity of Pc (4312), we propose measuring the beam spin asymmetry and decay kinematic polarization, quantities that can be accurately determined by the ePIC detector. Our approach can be extended to investigate other heavy pentaquarks produced in electron-proton and electron-deuteron collisions, as well as to study their interactions with nuclear matter in electron-heavy ion collisions. We strongly encourage the EIC community to explore this potential and integrate pentaquark studies as a critical element of the scientific mission.

   ↳ hep-phnucl-exnucl-th0 citations
7. 07*

   Probing New Forces with Nuclear Clocks

   Cédric Delaunay🇫🇷 · Seung J. Lee🇰🇷 · Roee Ozeri🇮🇱 · Gilad Perez🇮🇱 · Wolfram Ratzinger🇮🇱 · Bingrong Yu🇺🇸

   Clocks based on nuclear isomer transitions promise exceptional stability and precision. The low transition energy of the thorium-229 isomer makes it an ideal candidate, as it has been excited by a vacuum-ultraviolet laser and is highly sensitive to subtle interactions. This enables the development of powerful tools for probing new forces, which we call {\it quintessometers}. In this work, we demonstrate the potential of nuclear clocks, particularly solid-state variants, to surpass existing limits on scalar field couplings, exceeding the sensitivity of current fifth-force searches at submicron distances and significantly improving equivalence-principle tests at kilometer scales and beyond. Additionally, we highlight the capability of transportable nuclear clocks to detect scalar interactions at distances beyond $10$km, complementing space-based missions.

   ↳ hep-phnucl-exphysics.atom-phquant-phPRD(2025)·10 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.