Mon·Nov 11, 2024Monday·November 11, 2024

1. 01*

   High precision measurements of the proton elastic electromagnetic form factors and their ratio at $Q^2$ = 0.50, 2.64, 3.20, and 4.10 GeV${}^2$

   I. A. Qattan🇦🇪 · J. Arrington🇺🇸 · K. Aniol🇺🇸 · O. K. Baker🇺🇸 · R. Beams🇺🇸 · E. J. Brash🇺🇸 · A. Camsonne🇺🇸 · J.-P. Chen🇺🇸 · M. E. Christy🇺🇸 · D. Dutta🇺🇸 · R. Ent🇺🇸 · D. Gaskell🇺🇸 and 28 other authors

   The advent of high-intensity, high-polarization electron beams led to significantly improved measurements of the ratio of the proton's charge to electric form factors, GEp/GMp. However, high-$Q^2$ measurements yielded significant disagreement with extractions based on unpolarized scattering, raising questions about the reliability of the measurements and consistency of the techniques. Jefferson Lab experiment E01-001 was designed to provide a high-precision extraction of GEp/GMp from unpolarized cross section measurements using a modified version of the Rosenbluth technique to allow for a more precise comparison with polarization data. Conventional Rosenbluth separations detect the scattered electron which requires comparisons of measurements with very different detected electron energy and rate for electrons at different angles. Our Super-Rosenbluth measurement detected the struck proton, rather than the scattered electron, to extract the cross section. This yielded a fixed momentum for the detected particle and dramatically reduced cross section variation, reducing rate- and momentum-dependent corrections and uncertainties. We measure the cross section vs angle with high relative precision, allowing for extremely precise extractions of GEp/GMp at $Q^2$ = 2.64, 3.20, and 4.10 GeV${}^2$. Our results are consistent with traditional extractions but with much smaller corrections and systematic uncertainties, comparable to the uncertainties from polarization measurements. Our data confirm the discrepancy between Rosenbluth and polarization extractions of the proton form factor ratio using an improved Rosenbluth extraction that yields smaller and less-correlated uncertainties than typical of previous Rosenbluth extractions. We compare our results to calculations of two-photon exchange effects and find that the observed discrepancy can be relatively well explained by such effects.

   nucl-exPRC(2025)·13 citations
2. 02*

   Measurement of the $\psi (2S)$ to $J/\psi$ cross-section ratio as a function of centrality in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV

   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 1140 other authors

   The dissociation of quarkonium states with different binding energies produced in heavy-ion collisions is a powerful probe for investigating the formation and properties of the quark-gluon plasma. The ratio of production cross-sections of $\psi (2S)$ and $J/\psi$ mesons times the ratio of their branching fractions into the dimuon final state is measured as a function of centrality using data collected by the LHCb detector in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV. The measured ratio shows no dependence on the collision centrality, and is compared to the latest theory predictions and to the recent measurements in literature.

   nucl-exhep-exJHEP(2025)·14 citations
3. 03*

   New methods of neutrino and anti-neutrino detection from 0.115 to 105 MeV

   Nickolas Solomey🇺🇸 · Mark Christl🇺🇸 · Brian Doty🇺🇸 · Jonathan Folkerts🇺🇸 · Brooks Hartsock🇺🇸 · Evgen Kuznetsco🇩🇪 · Robert McTaggart🇺🇸 · Holger Meyer🇺🇸 · Tyler Nolan🇺🇸 · Greg Pawloski🇺🇸 · Daniel Reichart🇺🇸 · Miguel Rodriguez-Otero🇺🇸 · Dan Smith🇺🇸 · Lisa Solomey🇺🇸

   We have developed a neutrino detector with threshold energies from ~0.115 to 105 MeV in a clean detection mode almost completely void of accidental backgrounds. It was initially developed for the NASA $\nu$SOL project to put a solar neutrino detector very close to the Sun with 1,000 to 10,000 times higher solar neutrino flux than on Earth. Similar interactions have been found for anti-neutrinos, which were initially intended for Beta decay neutrinos from reactors, geological sources, or for nuclear security applications. These techniques work at the 1 to 100 MeV region for neutrinos from the ORNL Spallation Neutron Source or low energy accelerator neutrino and anti-neutrino production targets less than $\sim$100 MeV. The identification process is clean, with a double pulse detection signature within a time window between the first interaction producing the conversion electron or positron and the secondary gamma emission 100 ns to ~1 $\mu$s, which removes most accidental backgrounds. These new modes for neutrino and anti-neutrino detection of low energy neutrinos and anti-neutrinos could allow improvements to neutrino interaction measurements from an accelerator beam on a target.

   ↳ physics.ins-dethep-exnucl-ex0 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.