EPJ Web of Conferences
Volume 81, 2014MESON 2014 – 13th International Workshop on Production, Properties and Interaction of Mesons
|Number of page(s)||4|
|Section||Symmetries - contributions|
|Published online||26 November 2014|
Searching a dark photon with HADES
1 Technische Universität Darmstadt, 64289 Darmstadt, Germany
2 GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
a e-mail: firstname.lastname@example.org
Published online: 26 November 2014
The existence of a photon-like massive particle, the γ‘ or dark photon, is postulated in several extensions of the Standard Model to explain some recent puzzling astrophysical observations, as well as to solve the sofar unexplained deviation between the measured and calculated values of the muon anomaly. The dark photon, unlike the conventional photon, would have mass and would be detectable via its mixing with the latter. We present a search for the e+e− decay of such a hypothetical particle, 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 (ϵ2) at 90% CL has been obtained for the mass range M(U)= 0.02 - 0.55 GeV/c2 and is compared with the present world data set. Furthermore, an improved upper limit of 2.3 × 10−6 at 90% CL has been set on the branching ratio of the helicity-suppressed direct decay of the η meson η → e+e−.
© Owned by the authors, published by EDP Sciences, 2014
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.