@article{f5060f623d384b28b4d0ee0a301da61d,
title = "First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable e for γp →pπ0 and γp →nπ+",
abstract = "We report the measurement of the helicity asymmetry E for the pπ0 and nπ+ final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g., G) and circularly polarized photons (e.g., E) and a longitudinally polarized target. The new data cover a photon energy range 270-1400 MeV for the pπ0 final state (230-842 MeV for the nπ+ final state) and the full range of pion polar angles, θ, providing the most precise measurement of the observable E. A moment analysis gives a clear observation of the pη cusp in the pπ0 final state.",
author = "{(A2 Collaboration at MAMI)} and F. Afzal and K. Spieker and P. Hurck and S. Abt and P. Achenbach and P. Adlarson and Z. Ahmed and Akondi, {C. S.} and Annand, {J. R.M.} and Arends, {H. J.} and M. Bashkanov and R. Beck and M. Biroth and N. Borisov and A. Braghieri and Briscoe, {W. J.} and F. Cividini and C. Collicott and S. Costanza and A. Denig and M. Dieterle and Downie, {E. J.} and P. Drexler and S. Fegan and S. Gardner and D. Ghosal and Glazier, {D. I.} and I. Gorodnov and W. Gradl and D. Gurevich and L. Heijkenskj{\"o}ld and D. Hornidge and Huber, {G. M.} and Kashevarov, {V. L.} and Kay, {S. J.D.} and M. Korolija and B. Krusche and A. Lazarev and K. Livingston and S. Lutterer and Macgregor, {I. J.D.} and Macrae, {R. G.} and Manley, {D. M.} and Martel, {P. P.} and R. Miskimen and M. Mocanu and E. Mornacchi and Watts, {D. P.} and D. Werthm{\"u}ller and N. Zachariou",
note = "Publisher Copyright: {\textcopyright} 2024 authors. Published by the American Physical Society.",
year = "2024",
month = mar,
day = "19",
doi = "10.1103/PhysRevLett.132.121902",
language = "English",
volume = "132",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "12",
}