Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1911.05829

Improved limits on Fierz Interference using asymmetry measurements from the UCNA experiment

Xuan Sun·E. Adamek·B. Allgeier·Y. Bagdasarova·D. B. Berguno·M. Blatnik·T. J. Bowles·L. J. Broussard·M. A. -P. Brown·R. Carr·S. Clayton·C. Cude-Woods·S. Currie·E. B. Dees·X. Ding·B. W. Filippone·A. García·P. Geltenbort·S. Hasan·K. P. Hickerson·J. Hoagland·R. Hong·A. T. Holley·T. M. Ito·A. Knecht·C. -Y. Liu·J. Liu·M. Makela·R. Mammei·J. W. Martin·D. Melconian·M. P. Mendenhall·S. D. Moore·C. L. Morris·S. Nepal·N. Nouri·R. W. Pattie Jr.·A. Pérez Galván·D. G. Phillips II·R. Picker·M. L. Pitt·B. Plaster·D. J. Salvat·A. Saunders·E. I. Sharapov·S. Sjue·S. Slutsky·W. Sondheim·C. Swank·E. Tatar·R. B. Vogelaar·B. VornDick·Z. Wang·W. Wei·J. W. Wexler·T. Womack·C. Wrede·A. R. Young·B. A. Zeck
View original source ↗Read source document ↗Export metadata ↓

Abstract

The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the $β$-decay asymmetry parameter, $A_0$, for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their $β$-decay electrons are detected with $\approx 4π$ acceptance into two detector packages which provide position and energy reconstruction. The experiment also has sensitivity to $b_{n}$, the Fierz interference term in the neutron $β$-decay rate. In this work, we determine $b_{n}$ from the energy dependence of $A_0$ using the data taken during the UCNA 2011-2013 run. In addition, we present the same type of analysis using the earlier 2010 $A$ dataset. Motivated by improved statistics and comparable systematic errors compared to the 2010 data-taking run, we present a new $b_{n}$ measurement using the weighted average of our asymmetry dataset fits, to obtain $b_{n} = 0.066 \pm 0.041_{\text{stat}} \pm 0.024_{\text{syst}}$ which corresponds to a limit of $-0.012 < b_{n} < 0.144$ at the 90% confidence level.

Explore related subjects

nucl-ex

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Xuan Sun, E. Adamek, B. Allgeier, Y. Bagdasarova, D. B. Berguno, M. Blatnik, T. J. Bowles, L. J. Broussard, M. A. -P. Brown, R. Carr, S. Clayton, C. Cude-Woods, S. Currie, E. B. Dees, X. Ding, B. W. Filippone, A. García, P. Geltenbort, S. Hasan, K. P. Hickerson, J. Hoagland, R. Hong, A. T. Holley, T. M. Ito, A. Knecht, C. -Y. Liu, J. Liu, M. Makela, R. Mammei, J. W. Martin, D. Melconian, M. P. Mendenhall, S. D. Moore, C. L. Morris, S. Nepal, N. Nouri, R. W. Pattie Jr., A. Pérez Galván, D. G. Phillips II, R. Picker, M. L. Pitt, B. Plaster, D. J. Salvat, A. Saunders, E. I. Sharapov, S. Sjue, S. Slutsky, W. Sondheim, C. Swank, E. Tatar, R. B. Vogelaar, B. VornDick, Z. Wang, W. Wei, J. W. Wexler, T. Womack, C. Wrede, A. R. Young, B. A. Zeck. 2019-11-13. Improved limits on Fierz Interference using asymmetry measurements from the UCNA experiment. https://doi.org/10.1103/physrevc.101.035503

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Jet-like di-hadron correlations in pO, OO, and Ne--Ne collisions

Heavy-ion collisions are primarily studied to investigate the properties of hot and dense nuclear matter, known as the quark--gluon plasma (QGP). However, recent observations of hydrodynamic flow-like behaviour in pp and p--Pb collisions at the LHC suggest the possible formation of QGP droplets even in small collision systems. To bridge the multiplicity gap between small and large systems and to examine the applicability of hydrodynamic descriptions, light-ion collisions were performed for the first time at the LHC in 2025. This contribution presents measurements of the near-side peak width of di-hadron correlations in pO, OO, and Ne--Ne collisions with ALICE, used to search for medium effects. The width of the near-side correlation peak is studied as a function of the average charged-particle multiplicity at midrapidity. At low transverse momentum ($p_{\rm T}$), the near-side peak is broader in OO and Ne--Ne collisions than in pp and pO collisions, and in central collisions its width approaches that measured in Pb--Pb collisions. At higher $p_{\rm T}$ the peak narrows modestly with increasing multiplicity. The results are compared with PYTHIA, AMPT, and JETSCAPE calculations, none of which reproduces the measured widths over the full kinematic range.

nucl-ex↗
arXiv2026

Electromagnetic transition strength in $^{53}$Ca: the lifetime of the $5/2^{-}$ state

High-resolution in-beam $γ$-ray spectroscopy of $^{53}$Ca was performed at the Radioactive Isotope Beam Factory (RIBF) at RIKEN. Excited states in $^{53}$Ca were populated via one-neutron and one-proton removal reactions from a $^{55}$Sc radioactive beam, and the emitted $γ$ rays were detected using the HiCARI hybrid germanium detector array. The lifetime of the first excited $5/2^{-}$ state in $^{53}$Ca was measured for the first time through an analysis of Doppler-roadened $γ$-ray line shapes arising from relativistic recoil velocities. A lifetime of $τ = 11.3_{-11.3}^{+5.3(stat)+3(sys)}$ ps was deduced, corresponding to a reduced transition probability of $B(E2;5/2^{-}{\rightarrow}1/2^{-}) > 2.6 e^{2}fm^{4}$ at the 1$σ$ level, with a best-fit value of $4.5 e^{2}fm^{4}$. The measured transition strength is compared with state-of-the-art shell-model and ab initio calculations, providing a stringent benchmark for shell-model Hamiltonians and effective charges and modern ab initio descriptions of the neutron-rich calcium isotopes approaching the potential $N$ = 40 shell closure.

nucl-ex↗
arXiv2026

Measurements of $γ_v p \to π^+ π^-p'$ Cross Sections with the CLAS12 Detector for $Q^2$ from 2.4-8.0 GeV$^2$ and $W$ from 1.4-2.1 GeV

This paper reports exclusive cross sections for the $ep \to e'π^+π^-p'$ reaction using the CLAS12 detector at Jefferson Laboratory. The extractions of fully integrated and nine single-differential cross sections are presented for the first time for photon virtualities $Q^2$ from 2.4 to 8.0 GeV$^2$ and center-of-mass energies $W$ from 1.4 to 2.1 GeV, which covers a large part of the nucleon resonance region. These data considerably extend the kinematic reach of previous measurements from CLAS that covered $Q^2$ up to 5.0 GeV$^2$. Exclusive $γ_v p \to π^+ π^-p'$ cross section measurements are of particular importance for the extraction of $γ_vpN^*$ resonance electrocouplings across the $N^*$ spectrum, especially in the mass range above 1.6 GeV where several resonances decay preferentially to the $ππN$ final states. The electrocouplings with extended $Q^2$ coverage expected from these new data will enable an improved understanding of the emergence of $N^*$ mass and structure in the transition from the strongly coupled toward the perturbative QCD regime.

nucl-ex↗