Experimental search for the LSND anomaly with the ICARUS LAr-TPC detector in the CNGS beam

We report an early result from ICARUS (CNGS2), the large mass LAr-TPC, a Gargamelle class imaging detector of novel design. A search of a nu(mu) -> nu(e) signal due to a LSND anomaly at the Gran Sasso Laboratory, located at a distance of L = 730 km from CERN is hereby presented. Such an anomaly, in which an electron is produced by neutrinos in the energy interval 0 <= E-nu <= 30 GeV, will be characterized by a fast energy oscillation averaging closely to sin(2)(1.27 Delta m(new)(2)L/E-nu) similar or equal to 1/2 and therefore approximately with probability < P-nu mu -> nu e > = 1/2 sin(2)(2 theta(new)). The presence of such a signal will be compared with the small but significant backgrounds due to other and more conventional neutrino origins. Within the range of our observations, our result is compatible with the absence of a LSND anomaly. At 90% and 99% confidence levels the limits on the oscillation probabilities are < P-nu mu -> nu e > <= 5.4 x 10(-3) and < P-nu mu -> nu e > <= 1.1 x 10(-2) respectively. The present result strongly limits the window of opened options for the LSND anomaly, reducing the remaining effect to a narrow region centered around (Delta m(2), sin(2)(2 theta)) = (0.5 eV(2), 0.05) where there is an over-all agreement (at 90 % CL) between the present ICARUS limit, the published limits of KARMEN and the published positive signals of LSND and MiniBooNE collaborations.