Measurement of the $\phi \to \pi^0 e^+e^-$ transition form factor with the KLOE detector

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.; Czerwiński, 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.; Papenbrock, M.; Passeri, A.; Patera, Vincenzo; Perez Del Rio, E.; Ranieri, A.; Salabura P. Santangelo, P. Salabura P. Santangelo; Sarra, I.; Schioppa, M.; Silarski, M.; Sirghi, F.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.

doi:10.1016/j.physletb.2016.04.015

A measurement of the vector to pseudoscalar conversion decay ϕ→π0e+e−ϕ→π0e+e− with the KLOE experiment is presented. A sample of ∼9500 signal events was selected from a data set of 1.7 fb−1 of e+e−e+e− collisions at View the MathML sources∼mϕ collected at the DAΦNE e+e−e+e− collider. These events were used to perform the first measurement of the transition form factor |Fϕπ0(q2)||Fϕπ0(q2)| and a new measurement of the branching ratio of the decay: View the MathML sourceBR(ϕ→π0e+e−)=(1.35±0.05−0.10+0.05)×10−5. The result improves significantly on previous measurements and is in agreement with theoretical predictions.

Measurement of the $\phi \to \pi^0 e^+e^-$ transition form factor with the KLOE detector / 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., Czerwiński, 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. 362-367. [10.1016/j.physletb.2016.04.015]