Data di Pubblicazione:
2014
Abstract:
We present a search for the e(+)e(-) decay of a hypothetical dark photon, also named U vector boson, in inclusive dielectron spectra measured by HADES in the p(3.5 GeV) + p, Nb reactions, as well as the Ar (1.756 GeV/u) KCl reaction. An upper limit on the kinetic mixing parameter squared epsilon(2) at 90% CL has been obtained for the mass range M-U = 0.02-0.55 GeV/c(2) and is compared with the present world data set. For masses 0.03-0.1 GeV/c(2), the limit has been lowered with respect to previous results, allowing now to exclude a large part of the parameter region favored by the muon g - 2 anomaly. Furthermore, an improved upper limit on the branching ratio of 2.3 x 10(-6) has been set on the helicity-suppressed direct decay of the eta meson, eta --> e(+)e(-), at 90% CL.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
VECTOR GAUGE BOSON; PHI-MESON DECAYS
Elenco autori:
G. Agakishiev;A. Balanda;D. Belver;A. Belyaev;J.C. Berger-Chen;A. Blanco;M. Böhmer;J.L. Boyard;P. Cabanelas;S. Chernenko;A. Dybczak;E. Epple;L. Fabbietti;O. Fateev;P. Finocchiaro;P. Fonte;J. Friese;I. Fröhlich;T. Galatyuk;J.A. Garzón;R. Gernhäuser;K. Göbel;M. Golubeva;D. González-Díaz;F. Guber;M. Gumberidze;T. Heinz;T. Hennino;R. Holzmann;A. Ierusalimov;I. Iori;A. Ivashkin;M. Jurkovic;B. Kämpfer;T. Karavicheva;I. Koenig;W. Koenig;B.W. Kolb;G. Kornakov;R. Kotte;A. Krása;F. Krizek;R. Krücken;H. Kuc;W. Kühn;A. Kugler;A. Kurepin;V. Ladygin;R. Lalik;S. Lang;K. Lapidus;A. Lebedev;T. Liu;L. Lopes;M. Lorenz;L. Maier;A. Mangiarotti;J. Markert;V. Metag;B. Michalska;J. Michel;C. Müntz;L. Naumann;Y.C. Pachmayer;M. Palka;Y. Parpottas;V. Pechenov;O. Pechenova;V. Petousis;J. Pietraszko;W. Przygoda;B. Ramstein;A. Reshetin;A. Rustamov;A. Sadovsky;P. Salabura;T. Scheib;H. Schuldes;A. Schmah;E. Schwab;J. Siebenson;Yu.G. Sobolev;S. Spataro;B. Spruck;H. Ströbele;J. Stroth;C. Sturm;A. Tarantola;K. Teilab;P. Tlusty;M. Traxler;R. Trebacz;H. Tsertos;T. Vasiliev;V. Wagner;M. Weber;C. Wendisch;J. Wüstenfeld;S. Yurevich;Y. Zanevsky
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