We have searched for the K{sup +} {yields} {pi}{sup +}{gamma}{gamma} decay in the kinematic region with {pi}{sup +} momentum close to the end point. No events were observed, and the 90% ...confidence-level upper limit on the partial branching ratio was obtained, B(K{sup +} {yields} {pi}{sup +}{gamma}{gamma}, P > 213 MeV/c) < 8.3 x 10{sup -9} under the assumption of chiral perturbation theory including next-to-leading order ''unitarity'' corrections. The same data were used to determine an upper limit on the K{sup +} {yields} {pi}{sup +}{gamma} branching ratio of 2.3 x 10{sup -9} at the 90% confidence level.
Three events for the decay K{sup +}{yields}{pi}{sup +}{nu}{nu} have been observed in the pion momentum region below the K{sup +}{yields}{pi}{sup +}{pi}{sup 0} peak, 140<P{sub {pi}}<199 MeV/c, with an ...estimated background of 0.93{+-}0.17(stat.){sub -0.24}{sup +0.32}(syst.) events. Combining this observation with previously reported results yields a branching ratio of B(K{sup +}{yields}{pi}{sup +}{nu}{nu})=(1.73{sub -1.05}{sup +1.15})x10{sup -10} consistent with the standard model prediction.
To search for spontaneous conversion of muonium to antimuonium with very low background, a new signature was implemented that required the coincident detection of the decay products of the ...antimuonium atom, the energetic {ital e}{sup {minus}} and the atomic {ital e}{sup +}. No conversion events were seen, which sets an improved upper limit of 6.5{times}10{sup {minus}7} (90% C.L.) on the conversion probability. The corresponding limit on the coupling constant, using a {ital V}{minus}{ital A} form for the conversion Hamiltonian, is {ital G}{sub {ital M}{ital {bar M}}}{lt}0.16{ital G}{sub {ital F}} (90% C.L.), where {ital G}{sub {ital F}} is the Fermi coupling constant.
Intensity Frontier Instrumentation Kettell, S H; Rameika, R A; Tschirhart, R S
arXiv (Cornell University),
09/2013
Paper, Journal Article
Odprti dostop
This report summarizes findings of the 2013 Snowmass Community Summer Study Instrumentation Frontier's subgroup on the Intensity Frontier. This report is directed at identifying instrumentation R&D ...needed to support particle physics research over the coming decades at the Intensity Frontier.
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