Measurement of K-mu 3(0) form factors

Lai, A.; Marras, D.; Bevan, A.; Dosanjh, R. S.; Gershon, T. J.; Hay, B.; Kalmus, G. E.; Lazzeroni, C.; Munday, D. J.; Olaiya, E.; Parker, M. A.; White, T. O.; Wotton, S. A.; Barr, G.; Bocquet, G.; Ceccucci, A.; Cuhadar Donszelmann, T.; Cundy, D.; D'Agostini, G.; Doble, N.; Falaleev, V.; Gatignon, L.; Gonidec, A.; Gorini, B.; Govi, G.; Grafstrom, P.; Kubischta, W.; Lacourt, A.; Norton, A.; Palestini, S.; Panzer Steindel, B.; Taureg, H.; Velasco, M.; Wahl, H.; Cheshkov, C.; Hristov, P.; Kekelidze, V.; Litov, L.; Madigozhin, D.; Molokanova, N.; Potrebenikov, Y.; Stoynev, S.; Zinchenko, A.; Knowles, I.; Martin, V.; Sacco, R.; Walker, A.; Contalbrigo, M.; Dalpiaz, P.; Duclos, J.; Frabetti, P. L.; Gianoli, A.; Martini, M.; Petrucci, F.; Savrie, M.; Bizzeti, A.; Calvetti, M.; Collazuol, Gianmaria; Graziani, G.; Iacopini, E.; Lenti, M.; Ruggiero, G.; Veltri, M.; Becker, H. G.; Eppard, K.; Eppard, M.; Fox, H.; Kalter, A.; Kleinknecht, K.; Koch, U.; Kopke, L.; P. L., Da; Marouelli, P.; Pellmann, I.; Peters, A.; Renk, B.; Schmidt, S. A.; Schonharting, V.; Schue, Y.; Wanke, R.; Winhart, A.; Wittgen, M.; Chollet, J. C.; Fayard, L.; Iconomidou Fayard, I.; Ocariz, J.; Unal, G.; Wingerter Seez, I.; Anzivino, G.; Cenci, P.; Imbergamo, E.; Lubrano, P.; Mestvirishvili, A.; Nappi, A.; Pepe, M.; Piccini, M.; Bertanza, L.; Carosi, R.; Casali, R.; Cerri, C.; Cirilli, A.; Costantini, F.; Fantechi, R.; Giudici, S.; Mannelli, I.; Pierazzini, G.; Sozzi, M.; Cheze, J. B.; Cogan, J.; Beer, M. D.; Debu, P.; Formica, A.; R. G., De; Mazzucato, E.; Peyaud, B.; Turlay, R.; Vallage, B.; Bernhard, R.; Holder, M.; Maier, A.; Ziolkowski, M.; Arcidiacono, R.; Biino, C.; Cartiglia, N.; Marchetto, F.; Menichetti, E.; Pastrone, N.; Nassalski, J.; Rondio, E.; Szleper, M.; Wislicki, W.; Wronka, S.; Dibon, H.; Fischer, G.; Jeitler, M.; Markytan, M.; Mikulec, I.; Neuhofer, G.; Pernicka, M.; Taurok, A.; Widhalm, L.

doi:10.1016/j.physletb.2007.02.039

This Letter reports on a new high precision measurement of the form factors of the K-L -> pi(+/-) mu(-/+) nu(mu) decay. The data sample of about 2.3 x 10(6) events was recorded in 1999 by the NA48 experiment at CERN. Studying the Dalitz plot density we measured a linear, lambda(+)' = (20.5 +/- 2.2(stat) +/- 2.4(syst)) x 10(-3), and a quadratic, lambda(+)''(2.6 +/- 0.9(stat) +/- 1.0(syst)) x 10(-3) term in the power expansion of the vector form factor. No evidence was found for a second order term for the scalar form factor; the linear slope was determined to be lambda(o) = (9.5 +/- 1.1(stat) +/- 0.8(syst)) x 10(-3). Using a linear fit our results were: lambda(+) = (26.7 +/- 0.6(stat) +/- 0.8(syst)) x 10(-3) and lambda(o) = (11.7 +/- 0.7(stat) +/- 1.0(syst)) x 10(-3). A pole fit of the form factors yields: M-V = (905 +/- 9(stat) +/- 17(syst)) MeV/c(2) and m(S) = (1400 +/- 46(stat) +/- 53(syst)) Mev/c(2). (c) 2007 Elsevier B.V. All rights reserved.