Measurement of the parity-violating asymmetry in the N → Δ transition at low Q2 Letter

Adhikari, D, AlShayeb, T, Androić, D et al. (2025). Measurement of the parity-violating asymmetry in the N → Δ transition at low Q2 . PHYSICAL REVIEW C, 112(1), L0125011-L0125016. 10.1103/3xl1-jytq

cited authors

  • Adhikari, D; AlShayeb, T; Androić, D; Armstrong, DS; Asaturyan, A; Bartlett, K; Beminiwattha, RS; Benesch, J; Benmokhtar, F; Carlini, RD; Cornejo, JC; Dusa, SC; Dalton, MM; Davis, CA; Deconinck, W; Dunne, JA; Dutta, D; Duvall, WS; Elaasar, M; Falk, WR; Finn, JM; Gal, C; Gaskell, D; Gericke, MTW; Hoskins, JR; Jones, DC; Jones, MK; King, PM; Korkmaz, E; Kowalski, S; Leacock, J; Leckey, JP; Lee, AR; Lee, JH; Lee, L; MacEwan, S; Mack, D; Magee, JA; Mahurin, R; Mammei, J; Martin, JW; McHugh, MJ; Mesick, KE; Michaels, R; Micherdzinska, A; Mkrtchyan, A; Mkrtchyan, H; Ndukum, LZ; Nuhait, H; Nuruzzaman; van Oers, WTH; Page, SA; Pan, J; Paschke, KD; Phillips, SK; Pitt, ML; Radloff, RW; Rajotte, JF; Ramsay, WD; Roche, J; Sawatzky, B; Simicevic, N; Smith, GR; Solvignon, P; Spayde, DT; Subedi, A; Tobias, WA; Tvaskis, V; Waidyawansa, B; Wang, P; Wells, SP; Wood, SA; Zang, P; Zhamkochyan, S

authors

abstract

  • We report the measurement of the parity-violating asymmetry in the N → Δ transition via the e− + p→ e− + Δ+ reaction at two different kinematic points with low four-momentum transfer Q2. Measurements were made with incident electron beam energies of 0.877 and 1.16 GeV, corresponding to Q2 values of 0.0111 and 0.0208 (GeV/c)2, respectively. These measurements put constraints on a low-energy constant in the weak Lagrangian, dΔ, corresponding to a parity-violating electric-dipole transition matrix element. This matrix element has been shown to be large in the strangeness-changing channel, via weak hyperon decays such as Σ+ → pγ. The measurements reported here constrain dΔ in the strangeness-conserving channel. The final asymmetries were −0.65 ± 1.00(stat.) ± 1.02(syst.) ppm (parts per million) for 0.877 GeV and −3.59 ± 0.82(stat.) ± 1.33(syst.) ppm for 1.16 GeV. With these results we deduce a small value for dΔ, consistent with zero, in the strangenessconserving channel, in contrast to the large value for dΔ previously reported in the strangeness-changing channel.

publication date

  • July 17, 2025

published in

Digital Object Identifier (DOI)

start page

  • L0125011

end page

  • L0125016

volume

  • 112

issue

  • 1