V. F. Konstantinov

High statistic measurement of the K−→π0e−ν decay form-factors

The decay K- ->pi0 e- nu is studied using in-flight decays detected with the ISTRA+ spectrometer. About 920K events are collected for the analysis. The lambda+ slope parameter of the decay form-factor f+(t) in the linear approximation (average slope) is measured: lambda+(lin)= 0.02774 +- 0.00047(stat) +- 0.00032(syst). The quadratic contribution to the form-factor was estimated to be lambda+ = 0.00084 +- 0.00027(stat) +- 0.00031(syst). The linear slope, which has a meaning of df+(t)/dt|_{t=0} for this fit, is lambda+ = 0.02324 +- 0.00152(stat) +- 0.00032(syst). The limits on possible tensor and scalar couplings are derived: f_{T}/f_{+}(0)=-0.012 +- 0.021(stat) +- 0.011

High statistics study of the K−→π0μ−ν decay

(syst), f_{S}/f_{+}(0)=-0.0037^{+0.0066}_{-0.0056}(stat) +- 0.0041(syst).

Measurement of the Dalitz plot slope parameters for K−→π0π0π− decay using ISTRA+ detector

The decay K ! � 0 ehas been studied using in-flight decays detected with the ISTRA+ spectrometer operating in the 25-GeV negative secondary beam of the U-70 PS. About 550K events were collected for the analysis. The �+ parameter of the vec- tor form-factor has been measured: �+ = 0.0286 ± 0.0008(stat) ± 0.0006(syst). The limits on the possible tensor and scalar couplings have been obtained: fT/f+(0) = 0.021 +0.064 0.075 (stat) ± 0.026(syst); fS/f+(0) = 0.002 +0.020 0.022 (stat) ± 0.003(syst)

Study of the K− → μ−νπ0 decay

Abstract The Dalitz plot slope parameters g, h and k for the K−→π0π0π− decay have been measured using in-flight decays detected with the ISTRA+ setup operating in the 25xa0GeV negative secondary beam of the U-70 PS. About 252xa0K events with four-momenta measured for the π− and four involved photons were used for the analysis. The values obtained g=0.627±0.004(stat)±0.010(syst), h=0.046±0.004(stat)±0.012(syst), k=0.001±0.001(stat)±0.002(syst) are consistent with the world averages dominated by K+ data, but have significantly smaller errors.

Study of the K− → e−νπ0 decay

The decay K− → μ−νπ0 has been studied using in-flight decays detected with the ISTRA+ setup operating in the 25-GeV negative secondary beam of the U-70 PS. About 112K events were used for the analysis. The λ+ and λ0 slope parameters of the decay form factors f+(t) and f0(t) have been measured: λ+=0.0321±0.004(stat.)±0.002(syst.), λ0=0.0209±0.004(stat.)±0.002(syst.); the correlation dλ0/dλ+=−0.46. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.021±0.028(stat.)±0.014(theor.), fS/f+(0)=0.004±0.005(stat.)±0.005(theor.).

Study of \(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma \) decay with ISTRA+ setup

The decay K− → e−νπ0 has been studied using in-flight decays detected with the ISTRA+ setup working at the 25-GeV negative secondary beam of the U-70 PS. About 130K events were used for the analysis. The λ+ parameter of the vector form factor has been measured: λ+=0.0293±0.0015(stat.)±0.002(syst.). The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.045±0.060(stat.) and fS/f+(0)=−0.019−0.016+0.025(stat.).

Study of the K−→π0e−ν decay

AbstractResults of study of the n

Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector

K^ - to pi ^0 e^ - overline nu gamma