Mon·Jun 9, 2025Monday·June 9, 2025

1. 01*

   Investigation of ${}^{31}$P levels near the proton threshold by Nuclear Resonance Fluorescence and the impact on the ${}^{30}$Si(p,$\gamma$)${}^{31}$P thermonuclear rate

   David Gribble (1 and 2) · Christian Iliadis (1 and 2)🇺🇸 · Robert V.F. Janssens (1 and 2)🇺🇸 · Udo Friman-Gayer (3 and 2)🇸🇪 · Akaa D. Ayangeakaa (1 and 2)🇺🇸 · Art Champagne (1 and 2) · Emily Churchman (1 and 2) · William Fox (4 and 2) · Steven Frye (1 and 2) · Xavier K.-H. James (1 and 2) · Samantha R. Johnson (1 and 2) · Richard Longland (4 and 2)🇺🇸 and 4 other authors

   We investigated the nuclear structure of ${}^{31}$P near the proton threshold using Nuclear Resonance Fluorescence (NRF) to refine the properties of key resonances in the ${}^{30}$Si(p,$\gamma$)${}^{31}$P reaction, which is critical for nucleosynthesis in stellar environments. Excitation energies and spin-parities were determined for several states, including two unobserved resonances at $E_r$ $=$ $18.7$~keV and $E_r$ $=$ $50.5$~keV. The angular correlation analysis enabled the first unambiguous determination of the orbital angular momentum transfer for these states. These results provide a significant update to the ${}^{30}$Si(p,$\gamma$)${}^{31}$P thermonuclear reaction rate, with direct implications for models of nucleosynthesis in globular clusters and other astrophysical sites. The revised rate is substantially lower than previous estimates at temperatures below $200$~MK, affecting predictions for silicon isotopic abundances in stellar environments. Our work demonstrates the power of NRF in constraining nuclear properties, and provides a framework for future studies of low-energy resonances relevant to astrophysical reaction rates.

   nucl-exastro-ph.SRnucl-thPRC(2025)·1 citation
2. 02*

   Angela and the electric dipole response -- giant and pygmy, hot and cold, isoscalar and isovector

   Peter von Neumann-Cosel (1,2) ((1) Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany, (2) Norwegian Nuclear Research Center and Department of Physics, University of Oslo, Oslo, Norway)🇩🇪

   The impact of Angela Bracco's work on the electric dipole response of nuclei is discussed using three examples of current nuclear structure problems: disentangling different contributions to the decay width of the giant dipole resonance, the equivalence of photo- absorption and emission and the nature of the pygmy dipole resonance.

   nucl-exnucl-thEPJA(2025)·1 citation
3. 03*

   Coherent photoproduction of ${\rho }^0,\omega$ and excited vector mesons in ultraperipheral PbPb collisions

   LHCb collaboration: R. Aaij · A.S.W. Abdelmotteleb · C. Abellan Beteta · F. Abudinén · T. Ackernley · A. A. Adefisoye · B. Adeva · M. Adinolfi · P. Adlarson · C. Agapopoulou · C.A. Aidala · Z. Ajaltouni and 1139 other authors

   The invariant-mass distribution for the coherent photoproduction of dipions in ultraperipheral PbPb collisions is measured using data, corresponding to an integrated luminosity of $224.6\pm 9.6\mu$b${}^{-1}$, collected by the LHCb experiment in 2018 at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. In the mass range from 400 to 1200 MeV, the results are consistent with previous experiments, with the spectrum dominated by the ${\rho }^0$ meson, which interferes with a nonresonant component, together with a smaller $\omega$ meson contribution. In an extended mass range up to 2300 MeV, models previously used do not fit the data and a consistent description requires the introduction of two resonances at masses of $1350\pm 20$ MeV and $1790\pm 20$ MeV with widths of about 300 MeV. The cross-section for each meson is measured differentially in twelve bins of rapidity from 2.05 to 4.90. The ${\rho }^0$ cross-section increases with rapidity from about 400 to 600 mb and is measured with a typical precision of 8\%, while the cross-section times branching fraction for the $\omega ,{\rho }^{\prime }$ and ${\rho }^{\prime \prime }$, with the statistical precision of the data, do not have a pronounced rapidity dependence and are between 0.5 and 1.5 mb, with uncertainties up to 30\%. A large nuclear suppression is observed for the ${\rho }^0$ meson compared to expectations based on photoproduction on the proton that use the impulse approximation. Significant suppression is also observed compared to that predicted by elastic scattering described in the Glauber approach, or with the addition of inelastic scattering in a Gribov--Glauber model.

   nucl-exhep-exJHEP(2025)·15 citations
4. 04*

   Measuring spin correlation between quarks during QCD confinement

   The STAR Collaboration

   The vacuum is now understood to possess a rich and complex structure, characterized by fluctuating energy fields and a condensate of virtual quark-antiquark pairs. The spontaneous breaking of the approximate chiral symmetry, signaled by the nonvanishing quark condensate $⟨q\bar{q}⟩$, is dynamically generated through topologically nontrivial gauge configurations such as instantons. The precise mechanism linking the chiral symmetry breaking to the mass generation associated with quark confinement remains a profound open question in Quantum Chromodynamics (QCD) - the fundamental theory of strong interaction. High energy proton-proton collisions could liberate virtual quark-antiquark pairs from the vacuum that subsequently undergo confinement to form hadrons, whose properties could serve as probes into QCD confinement and the quark condensate. Here, we report evidence of spin correlations in $\Lambda \bar{\Lambda }$ hyperon pairs inherited from spin-correlated strange quark-antiquark virtual pairs. Measurements by the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory reveal a relative polarization signal of $(18\pm 4)\%$ that links the virtual spin-correlated quark pairs from the QCD vacuum to their final-state hadron counterparts. Crucially, this correlation vanishes when the hyperon pairs are widely separated in angle, consistent with the decoherence of the quantum system. Our findings provide a new experimental paradigm for exploring the dynamics and interplay of quark confinement and entanglement.

   ↳ hep-exhep-phhep-thnucl-ex+1Nature(2026)·38 citations
5. 05*

   Challenging Spontaneous Quantum Collapse with XENONnT

   E. Aprile · J. Aalbers · K. Abe · S. Ahmed Maouloud · L. Althueser · B. Andrieu · E. Angelino · D. Antón Martin · S. R. Armbruster · F. Arneodo · L. Baudis · M. Bazyk and 165 other authors

   We report on the search for X-ray radiation as predicted from dynamical quantum collapse with low-energy electronic recoil data in the energy range of 1-140 keV from the first science run of the XENONnT dark matter detector. Spontaneous radiation is an unavoidable effect of dynamical collapse models, which were introduced as a possible solution to the long-standing measurement problem in quantum mechanics. The analysis utilizes a model that for the first time accounts for cancellation effects in the emitted spectrum, which arise in the X-ray range due to the opposing electron-proton charges in xenon atoms. New world-leading limits on the free parameters of the Markovian continuous spontaneous localization and Diósi-Penrose models are set, improving previous best constraints by two orders of magnitude and a factor of five, respectively. The original values proposed for the strength and the correlation length of the continuous spontaneous localization model are excluded experimentally for the first time.

   ↳ hep-exhep-thnucl-exquant-phPRL(2026)·9 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.