Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Mar 22;132(12):121902.
doi: 10.1103/PhysRevLett.132.121902.

First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable E for γp→pπ^{0} and γp→nπ^{+}

F Afzal  1 , K Spieker  1 , P Hurck  2 , S Abt  3 , P Achenbach  4 , P Adlarson  4 , Z Ahmed  5 , C S Akondi  6 , J R M Annand  2 , H J Arends  4 , M Bashkanov  7 , R Beck  1 , M Biroth  4 , N Borisov  8 , A Braghieri  9 , W J Briscoe  10 , F Cividini  4 , C Collicott  11 , S Costanza  9   12 , A Denig  4 , M Dieterle  3 , E J Downie  10 , P Drexler  4   13 , S Fegan  7 , S Gardner  2 , D Ghosal  3 , D I Glazier  2 , I Gorodnov  8 , W Gradl  4 , D Gurevich  14 , L Heijkenskjöld  4 , D Hornidge  15 , G M Huber  5 , V L Kashevarov  4   8 , S J D Kay  7 , M Korolija  16 , B Krusche  3 , A Lazarev  8 , K Livingston  2 , S Lutterer  3 , I J D MacGregor  2 , R G Macrae  2 , D M Manley  6 , P P Martel  4   15 , R Miskimen  17 , M Mocanu  7 , E Mornacchi  4 , C Mullen  2 , A Neganov  8 , A Neiser  4 , M Oberle  3 , M Ostrick  4 , P B Otte  4 , D Paudyal  5 , P Pedroni  9 , A Powell  2 , G Reicherz  18 , T Rostomyan  3 , C Sfienti  4 , V Sokhoyan  4 , O Steffen  4 , I I Strakovsky  10 , T Strub  3 , I Supek  16 , A Thiel  1 , M Thiel  4 , A Thomas  4 , Yu A Usov  8 , S Wagner  4 , N K Walford  3 , D P Watts  7 , D Werthmüller  7 , J Wettig  4 , L Witthauer  3 , M Wolfes  4 , N Zachariou  7 ; A2 Collaboration at MAMI
Affiliations

First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable E for γp→pπ^{0} and γp→nπ^{+}

F Afzal et al. Phys Rev Lett. .

Abstract

We report the measurement of the helicity asymmetry E for the pπ^{0} 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 pπ^{0} 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 pπ^{0} final state.

PubMed Disclaimer