Mon·Aug 28, 2023Monday·August 28, 2023

1. 01*

   First direct ${}^7$Be electron capture $Q$-value measurement towards high-precision BSM neutrino physics searches

   R. Bhandari🇺🇸 · G. Bollen🇺🇸 · T. Brunner🇨🇦 · N. D. Gamage🇺🇸 · A. Hamaker🇺🇸 · Z.Hockenbery🇨🇦 · M. Horana Gamage🇺🇸 · D. K. Keblbeck🇺🇸 · K. G. Leach🇺🇸 · D. Puentes🇺🇸 · M. Redshaw🇺🇸 · R. Ringle🇺🇸 and 3 other authors

   We report the first direct measurement of the nuclear electron capture (EC) decay $Q$-value of ${}^7$Be $\to$ ${}^7$Li via high-precision Penning trap mass spectrometry (PTMS). This was performed using the LEBIT Penning trap located at the National Superconducting Cyclotron Laboratory/Facility for Rare Isotope Beams (NSCL/FRIB) using the newly commissioned Batch-Mode Ion-Source (BMIS) to deliver the unstable ${}^7$Be${}^{+}$ samples. With a measured value of $Q_{EC}$ = 861.963(23) keV this result is also three times more precise than any previous determination of this quantity. This improved precision, and accuracy of the ${}^7$Be EC decay $Q$-value is critical for ongoing experiments that measure the recoiling nucleus in this system as a signature to search for beyond Standard Model (BSM) neutrino physics using ${}^7$Be-doped superconducting sensors.

   nucl-exPRC(2024)·5 citations
2. 02*

   Proton's gluon GPDs at large skewness and gravitational form factors from near threshold heavy quarkonium photo-production

   Yuxun Guo🇺🇸 · Xiangdong Ji🇺🇸 · Feng Yuan🇺🇸

   We study the exclusive near-threshold photo-production of heavy quarkonium in the framework of the generalized parton distribution (GPD) factorization, taking the $J/\psi$ production as an example. Due to the threshold kinematics, the Compton-like amplitudes are related to gluon GPDs at large skewness $\xi$, distinct from the common kinematics in asymptotic high energy where the skewness is typically small. We discuss the nature of large-$\xi$ expansion of these amplitudes in terms of the moments of gluon GPDs in the large-$\xi$ limit. Based on that, we propose several ways to extract the first few moments of the gluon GPDs from these amplitudes, with the leading ones corresponding to the gluonic gravitational or energy-momentum tensor form factors (GFFs). We apply these methods to analyze the recent near-threshold $J/\psi$ production measurements by the $J/\psi$ 007 experiment and GlueX collaboration, and find that the $\xi$-scaling of the measured differential cross sections is consistent with the asymptotic behavior. However, the current data are not accurate enough yet for a complete determination of the gluonic GFFs, and therefore we consider some prospects for better extractions in the future.

   ↳ hep-phnucl-exPRD(2024)·41 citations
3. 03*

   Exclusive QCD Factorization and Single Transverse Polarization Phenomena at High-Energy Colliders

   Zhite Yu🇺🇸

   This Ph.D.~thesis is divided into two distinct parts. The first part focuses on hard exclusive scattering processes in Quantum Chromodynamics (QCD) at high energies, while the second part delves into spin phenomena at the Large Hadron Collider (LHC). Hard exclusive scattering processes play a crucial role in QCD at high energies, providing unique insights into the confined partonic dynamics within hadrons, complementing inclusive processes. Studying these processes within the QCD factorization approach yields the generalized parton distribution (GPD), a nonperturbative parton correlation function that offers a three-dimensional tomographic parton image within a hadron. However, the experimental measurement of these processes poses significant challenges. This thesis will review the factorization formalism for related processes, examine the limitations of some widely used processes, and introduce two novel processes that enhance the sensitivity to GPD, particularly its dependence on the parton momentum fraction $x$. The second part of the thesis centers on spin phenomena, specifically single spin production, at the LHC. Noting that a single transverse polarization can be generated even in an unpolarized collision, this research proposes two new jet substructure observables: one for boosted top quark jets and another for high-energy gluon jets. The observation of these phenomena paves the way for innovative tools in LHC phenomenology, enabling both precision measurements and the search for new physics.

   ↳ hep-phhep-latnucl-exnucl-th5 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.