Mon·Aug 2, 2021Monday·August 2, 2021

1. 01*

   Constraining new physics with a novel measurement of the ${}^{23}$Ne $\beta$-decay branching ratio

   Yonatan Mishnayot · Ayala Glick-Magid🇮🇱 · Hitesh Rahangdale🇺🇸 · Guy Ron🇮🇱 · Doron Gazit🇮🇱 · Jason T. Harke🇺🇸 · Micha Hass · Ben Ohayon🇨🇭 · Aaron Gallant🇫🇷 · Nicholas D. Scielzo🇺🇸 · Sergey Vaintruab · Richard O. Hughes and 11 other authors

   Measurements of the beta-neutrino correlation coefficient (a${}_{\beta \nu }$) in nuclear beta decay, together with the Fierz interference term (b${}_F$), provide a robust test for the existence of exotic interactions beyond the Standard Model of Particle Physics. The extraction of these quantities from the recoil ion spectra in $\beta$-decay requires accurate knowledge, decay branching ratios, and high-precision calculations of higher order nuclear effects. Here, we report on a new measurement of the ${}^{23}$Ne $\beta$-decay branching ratio, which allows a reanalysis of existing high-precision measurements. Together with new theoretical calculations of nuclear structure effects, augmented with robust theoretical uncertainty, this measurement improves on the current knowledge of a${}_{\beta \nu }$ in ${}^{23}$Ne by an order of magnitude, and strongly constrains the Fierz term in beta decays, making this one of the first extractions to constrain both terms simultaneously. Together, these results place bounds on the existence of exotic tensor interactions and pave the way for new, even higher precision, experiments.

   nucl-exnucl-th5 citations
2. 02*

   DIS2021 Workshop Proceedings: Backward-Angle (u-Channel) Meson Production from JLab 12 GeV Hall C to EIC

   W. B. Li🇺🇸

   The recent exclusive backward-angle electroproduction of omega from Jefferson Lab Hall C electron-proton fixed-target scattering experiments above the resonance region hints at a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. Thanks to this effort, the interest in studying nucleon structure through u-channel meson production observables has grown significantly. In the fixed target configuration, the u-channel meson electroproduction observables feature a unique interaction picture: the target proton absorbs nearly all momentum induced by virtual photons and recoils forward, while the produced mesons (such as omega or pions) are left behind almost at rest near the target station. In this presentation, We provide a summary of the key observations of the existing u-channel meson production results, update-to-date theory insights, and a path to further exploration from JLab 12 GeV Hall C program to the future Electron-Ion Colliders.

   nucl-exhep-phnucl-thSciPost Phys.Proc.(2022)·1 citation
3. 03*

   Measurement of splittings along a jet shower in $\sqrt{s}=200$ GeV pp collisions at STAR

   Raghav Kunnawalkam Elayavalli (for the STAR Collaboration)🇺🇸

   Jets are algorithmic proxies of hard scattered partons, i.e. quarks and gluons, in high energy particle collisions. The STAR collaboration presents the first measurements of substructure observables at the first, second and third splits in the jet clustering tree via the iterative SoftDrop procedure. For each of these splits, we measure the fully corrected groomed shared momentum fraction (\zg) and groomed jet radius (\rg). We discuss the evolution of jet substructure in both the angular and momentum scales which allows for a self-similarity test of the DGLAP splitting function. We compare the fully corrected data to Monte Carlo models, providing stringent constraints on model parameters related to the parton shower and non-perturbative effects such as hadronization.

   ↳ hep-exnucl-exSciPost Phys.Proc.(2022)·2 citations
4. 04*

   Update on $|V_{us}|$ and $|V_{us}/V_{ud}|$ from semileptonic kaon and pion decays

   Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · William J. Marciano🇺🇸 · Ulf-G. Meißner🇩🇪

   We discuss the recent progress in the study of semileptonic kaon and pion decays, including new experimental results, improved electroweak radiative corrections, form factor calculations and isospin-breaking effects. As a result, we obtain $|V_{us}|=0.22309(40)(39)(3)$ from kaon semileptonic decays and $|V_{us}/V_{ud}|=0.22908(66)(41)(40)(2)(1)$ from the ratio between the kaon and pion semileptonic decay rates. We report an apparent violation of the top-row Cabibbo-Kobayashi-Maskawa matrix unitarity at a $3.2\sim 5.6\sigma$ level, and a discrepancy at a $2.2\sigma$ level between the value of $|V_{us}/V_{ud}|$ determined from the vector and axial charged weak interactions. Prospects for future improvements in those comparative precision tests involving $|V_{ud}|$, $|V_{us}|$ and their implications for physics beyond the Standard Model are described.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2022)·67 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.