Limit on the production of a new vector boson in $\mathrme^+ e^-\rightarrow \rm U\gamma$, U$\rightarrow \pi^+\pi^-$ with the KLOE experiment

Anastasi, A.; Babusci, D.; Bencivenni, G.; Berlowski, M.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkeståhl, L.; Cao, B.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwinski, E.; D'Agostini, Giulio; Danè, E.; De Leo, V.; De Lucia, E.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, Antonio; Di Salvo, R.; Domenici, D.; D'Uffizi, A.; Fantini, A.; Felici, G.; Fiore, S.; Gajos, A.; Gauzzi, Paolo; Giardina, G.; Giovannella, S.; Graziani, E.; Happacher, F.; Heijkenskjöld, L.; Ikegami Andersson, W.; Johansson, T.; Kamińska, D.; Krzemien, W.; Kupsc, A.; Loffredo, S.; Mandaglio, G.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Palladino, A.; Papenbrock, M.; Passeri, A.; Patera, Vincenzo; Perez Del Rio, E.; Ranieri, A.; Santangelo, P.; Sarra, I.; Schioppa, M.; Silarski, M.; Sirghi, F.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.

doi:10.1016/j.physletb.2016.04.019

The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in e+e−→Uγe+e−→Uγ, U→π+π−U→π+π− based on 28 million e+e−→π+π−γe+e−→π+π−γ events collected at DAΦNE by the KLOE experiment. The π+π+π−π− production by initial-state radiation compensates for a loss of sensitivity of previous KLOE View the MathML sourceU→e+e−, View the MathML sourceμ+μ− searches due to the small branching ratios in the ρ–ωρ–ω resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, ε2ε2, in the U mass range between 527 and View the MathML source987MeV. Above 700 MeV this new limit is more stringent than previous ones.

Limit on the production of a new vector boson in $\mathrme^+ e^-\rightarrow \rm U\gamma$, U$\rightarrow \pi^+\pi^-$ with the KLOE experiment / Anastasi, A., Babusci, D., Bencivenni, G., Berlowski, M., Bloise, C., Bossi, F., Branchini, P., Budano, A., Caldeira Balkeståhl, L., Cao, B., Ceradini, F., Ciambrone, P., Curciarello, F., Czerwinski, E., D'Agostini, G., Danè, E., De Leo, V., De Lucia, E., De Santis, A., De Simone, P., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - B757:(2016), pp. 356-361. [10.1016/j.physletb.2016.04.019]