2001-xxx

March 27, 2002

OEF

Study of the $K^{-} \rightarrow \pi^{0} e \nu$ decay

I.V. Ajinenko, S.A. Akimenko, G.A. Akopdzhanov, K.S. Belous, I.G. Britvich, G.I. Britvich, A.P. Filin, V.N. Govorun, A.V. Inyakin, V.F. Konstantinov, A.S. Konstantinov, I.Y. Korolkov, V.A. Khmelnikov, V.M. Leontiev, V.P. Novikov, V.F. Obraztsov, V.A. Polyakov, V.I. Romanovsky, V.M. Ronjin, V.A. Senko, N.A. Shalanda, M.M. Shapkin, V.I. Shelikhov, N.E. Smirnov, A.A. Sokolov, O.G. Tchikilev, E.V. Vlasov, O.P. Yushchenko.

$Institute~for~High~Energy~Physics,~Protvino,~Russia$

V.N. Bolotov, S.V. Laptev, A.Yu. Polyarush, V.E. Postoev $Institute~for~Nuclear~Research,~Moscow,~Russia$ S.V. Yaschenko, B.Zh. Zalikhanov, V.Z. Serdyuk. $Joint~ Institute for Nuclear Research, ~Dubna,~Russia$

Abstract

The decay $K^{-} \rightarrow \pi^{0} e \nu$ has been studied using inflight decays detected with "ISTRA+" setup working at the 25 GeV negative secondary beam of the U-70 PS. About 130K events were used for the analysis. The $\lambda_{+}$ parameter of the vector formfactor has been measured: $\lambda_{+}= 0.0306 \pm 0.0018(stat) \pm 0.002(syst)$. The limits on the possible tensor and scalar couplings have been derived: $f_{T}/f_{+}(0)=-0.044 \pm 0.068(stat) ;$ $f_{S}/f_{+}(0)=-0.015 \pm 0.025(stat)$

áÎÎÏÔÁÃÉÑ

ðÒÅÄÓÔÁ×ÌÅÎ ÁÎÁÌÉÚ ÒÁÓÐÁÄÁ $K^{-} \rightarrow \pi^{0} e \nu$. 130 ÔÙÓÑÞ ÓÏÂÙÔÉÊ ÜÔÏÇÏ ÒÁÓÐÁÄÁ ÚÁÒÅÇÉÓÔÒÉÒÏ×ÁÎÙ ÎÁ ÕÓÔÁÎÏ×ËÅ "éóôòá+" ÒÁÂÏÔÁÀÝÅÊ ÎÁ 25 çÜ÷ ÐÕÞËÅ ÏÔÒÉÃÁÔÅÌØÎÙÈ ÞÁÓÔÉà õ-70. éÚÍÅÒÅÎ ÐÁÒÁÍÅÔÒ ÎÁËÌÏÎÁ ×ÅËÔÏÒÎÏÇÏ ÆÏÒÍÆÁËÔÏÒÁ ÒÁÓÐÁÄÁ: $\lambda_{+}= 0.0306 \pm 0.0018(stat) \pm 0.002(syst)$. ðÏÌÕÞÅÎÙ ÏÇÒÁÎÉÞÅÎÉÑ ÎÁ ËÏÎÓÔÁÎÔÙ ÓËÁÌÑÒÎÏÇÏ É ÔÅÎÚÏÒÎÏÇÏ ×ËÌÁÄÏ×: $f_{T}/f_{+}(0)=-0.044 \pm 0.068(stat) ;$ $f_{S}/f_{+}(0)=-0.015 \pm 0.025(stat)$