Fri·Mar 15, 2024Friday·March 15, 2024

1. 01*

   Hybrid analysis of radiative corrections to neutron decay with current algebra and effective field theory

   Chien-Yeah Seng🇺🇸

   We introduce a useful framework for high-precision studies of the neutron beta decay by merging the current algebra description and the fixed-order effective field theory calculation of the electroweak radiative corrections to the neutron axial form factor. We discuss the advantages of this hybrid method and show that it only requires a minimal amount of lattice QCD inputs to achieve a $10^{-4}$ theory accuracy for the Standard Model prediction of the neutron lifetime and the axial-to-vector coupling ratio $\lambda$, both important to the search for physics beyond the Standard Model.

   ↳ hep-phhep-exhep-latnucl-ex+1JHEP(2024)·12 citations
2. 02*

   Observation and differential cross section measurement of neutral current DIS events with an empty hemisphere in the Breit frame

   The H1 collaboration: V. Andreev (50) · M. Arratia (34)🇺🇸 · A. Baghdasaryan (46)🇦🇲 · A. Baty (9)🇺🇸 · K. Begzsuren (40)🇲🇳 · A. Bolz (17)🇩🇪 · V. Boudry (30)🇫🇷 · G. Brandt (15)🇩🇪 · D. Britzger (26)🇩🇪 · A. Buniatyan (7)🇬🇧 · L. Bystritskaya (50) · A.J. Campbell (17)🇩🇪 and 136 other authors

   The Breit frame provides a natural frame to analyze lepton-proton scattering events. In this reference frame, the parton model hard interactions between a quark and an exchanged boson defines the coordinate system such that the struck quark is back-scattered along the virtual photon momentum direction. In Quantum Chromodynamics (QCD), higher order perturbative or non-perturbative effects can change this picture drastically. As Bjorken-$x$ decreases below one half, a rather peculiar event signature is predicted with increasing probability, where no radiation is present in one of the two Breit-frame hemispheres and all emissions are to be found in the other hemisphere. At higher orders in ${\alpha }_s$ or in the presence of soft QCD effects, predictions of the rate of these events are far from trivial, and that motivates measurements with real data. We report on the first observation of the empty current hemisphere events in electron-proton collisions at the HERA collider using data recorded with the H1 detector at a center-of-mass energy of 319 GeV. The fraction of inclusive neutral-current DIS events with an empty hemisphere is found to be $0.0112\pm 3.9{\%}_{\text{stat}}\pm 4.5{\%}_{\text{syst}}\pm 1.6{\%}_{\text{mod}}$ in the selected kinematic region of $150<Q^2<1500$ GeV${}^2$ and inelasticity $0.14<y<0.7$. The data sample corresponds to an integrated luminosity of 351.1 pb${}^{-1}$, sufficient to enable differential cross section measurements of these events. The results show an enhanced discriminating power at lower Bjorken-$x$ among different Monte Carlo event generator predictions.

   ↳ hep-exhep-phnucl-exEPJC(2024)·19 citations
3. 03*

   Injection and capture of antiprotons in a Penning-Malmberg trap using a drift tube accelerator and degrader foil

   C. Amsler🇦🇹 · H. Breuker🇯🇵 · M. Bumbar🇨🇭 · S. Chesnevskaya🇦🇹 · G. Costantini🇮🇹 · R. Ferragut🇮🇹 · M. Giammarchi🇮🇹 · A. Gligorova🇦🇹 · G. Gosta🇮🇹 · H. Higaki🇯🇵 · M. Hori🇬🇧 · E.D. Hunter🇦🇹 and 24 other authors

   The Antiproton Decelerator (AD) at CERN provides antiproton bunches with a kinetic energy of 5.3 MeV. The Extra-Low ENergy Antiproton ring at CERN, commissioned at the AD in 2018, now supplies a bunch of electron-cooled antiprotons at a fixed energy of 100 keV. The MUSASHI antiproton trap was upgraded by replacing the radio-frequency quadrupole decelerator with a pulsed drift tube to re-accelerate antiprotons and optimize the injection energy into the degrader foils. By increasing the beam energy to 119 keV, a cooled antiproton accumulation efficiency of (26 +- 6)% was achieved.

   ↳ physics.acc-phhep-exnucl-exNucl.Instrum.Meth.A(2024)·8 citations
4. 04*

   Radiative lifetime of the A 2{\Pi}1/2 state in RaF with relevance to laser cooling

   M. Athanasakis-Kaklamanakis · S. G. Wilkins · P. Lassègues · L. Lalanne · J. R. Reilly · O. Ahmad · M. Au · S. W. Bai · J. Berbalk · C. Bernerd · A. Borschevsky · A. A. Breier and 29 other authors

   The radiative lifetime of the $A$ ${}^2{\Pi }_{1/2}$ (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate $\Gamma =2.86(8)\times 10^7$ $s^{-1}$ are of relevance to the laser cooling of RaF via the optically closed $A$ ${}^2{\Pi }_{1/2}\leftarrow X$ ${}^2{\Sigma }_{1/2}$ transition, which makes the molecule a promising probe to search for new physics. RaF is found to have a comparable photon-scattering rate to homoelectronic laser-coolable molecules. Thanks to its highly diagonal Franck-Condon matrix, it is expected to scatter an order of magnitude more photons than other molecules when using just 3 cooling lasers, before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the $8P_{3/2}$ state in Fr to be 83(3) ns, in agreement with literature.

   ↳ physics.atom-phnucl-exPRA(2024)·11 citations
5. 05*

   A Segmented Total Energy Detector (sTED) optimized for $(n,\gamma )$ cross-section measurements at n_TOF EAR2

   V. Alcayne · D. Cano-Ott · J. Garcia · E. Gonzalez-Romero · T. Martinez · A. Perez de Rada · J. Plaza · A. Sanchez-Caballero · J. Balibrea-Correa · C. Domingo-Pardo · J. Lerendegui-Marco · A. Casanovas and 3 other authors

   The neutron time-of-flight facility n_TOF at CERN is a spallation source dedicated to measurements of neutron-induced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of $4\times 10^7$ neutrons per nominal proton pulse, which is 50 times higher than the one of Experimental ARea 1 (EAR1) of $8\times 10^5$ neutrons per pulse. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detectors response, by reducing the active volume per module and by using a photomultiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to $\gamma$-rays, and provides as well details of the use of the Pulse Height Weighting Technique (PHWT) with this detector. The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV. The detector has already been successfully used in several measurements at n_TOF EAR2.

   ↳ physics.ins-detnucl-exRadiat.Phys.Chem.(2024)·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.