Test of exotic scalar and tensor couplings in K+→π0e+ν decay

Abstract The form factors of the decay K + → π 0 e + ν ( K e 3 + ) have been measured with stopped kaons. A Dalitz plot containing 4.1×10 4 events was analyzed. A comparison of the observed Dalitz plot with a Monte Carlo simulation determined the ratio of the strengths of possible scalar and tensor couplings to that of the vector coupling, f S / f + (0)=−0.002±0.026(stat)±0.014(syst) and f T / f + (0)=−0.01±0.14(stat)±0.09(syst). These values are consistent with the standard model prediction of zero, and disagree with a previous experiment. The analysis also yielded the coefficient of the q 2 term in the vector form factor to be λ + =0.0278±0.0026(stat)±0.0030(syst).