24 research outputs found

    Search for the decay K+→π+ννˉK^+\to \pi^+ \nu \bar\nu in the momentum region Pπ<195 MeV/cP_\pi < 195 {\rm ~MeV/c}

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    We have searched for the decay K+→π+ννˉK^+ \to \pi^+ \nu \bar\nu in the kinematic region with pion momentum below the K+→π+π0K^+ \to \pi^+ \pi^0 peak. One event was observed, consistent with the background estimate of 0.73±0.180.73\pm 0.18. This implies an upper limit on B(K+→π+ννˉ)<4.2×10−9B(K^+ \to \pi^+ \nu \bar\nu)< 4.2\times 10^{-9} (90% C.L.), consistent with the recently measured branching ratio of (1.57−0.82+1.75)×10−10(1.57^{+1.75}_{-0.82}) \times 10^{-10}, obtained using the standard model spectrum and the kinematic region above the K+→π+π0K^+ \to \pi^+ \pi^0 peak. The same data were used to search for K+→π+X0K^+ \to \pi^+ X^0, where X0X^0 is a weakly interacting neutral particle or system of particles with 150<MX0<250 MeV/c2150 < M_{X^0} < 250 {\rm ~MeV/c^2}.Comment: 4 pages, 2 figure

    Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c

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    We have searched for the K+ to pi+ gamma gamma decay in the kinematic region with pi+ 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+ to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 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+ to pi+ gamma branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for publication in Physics Letters

    The research-teaching nexus: A case study of students' awareness, experiences and perceptions of research

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    This paper presents a case study of students' awareness, experiences and perceptions of research in a 'new' university in the UK. The findings are based on a questionnaire of almost 200 students and five small group interviews. Many of the students participating in this research perceived clear benefits to their learning from staff research, including being taught by enthusiastic staff, enhanced staff credibility, and the reflected glory of being taught by well-known researchers. However, they also perceived disadvantages, particularly with regard to staff availability, and did not believe that staff research should take priority over their needs as learners. They recognised that their awareness of the nature of research and the development of research skills increased most when they were actively involved in undertaking research projects. Several students also perceived benefits for future employment from their participation in research activities. The questionnaire has been used by several other universities around the world to benchmark their practices. © 2010 Taylor & Francis

    Further search for the decay K+→π+ννˉK^+ \to \pi^+ \nu \bar \nu in the momentum region P < 195 MeV/c

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    We report the results of a search for the decay K+→π+ννˉK^+ \to \pi^+ \nu \bar \nu in the kinematic region with π+\pi^+ momentum 140<P<195140 < P < 195 MeV/c using the data collected by the E787 experiment at BNL. No events were observed. When combined with our previous search in this region, one candidate event with an expected background of 1.22±0.241.22 \pm 0.24 events results in a 90% C.L. upper limit of 2.2×10−92.2 \times 10^{-9} on the branching ratio of K+→π+ννˉK^+ \to \pi^+ \nu \bar \nu. We also report improved limits on the rates of K+→π+X0K^+ \to \pi^+ X^0 and K+→π+X1X2K^+ \to \pi^+ X^1 X^2 where X0,X1,X2X^0, X^1, X^2 are hypothetical, massless, long-lived neutral particles.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.
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