Publication

Search for B- -> mu(-)(nu)over-bar(mu) Decays at the Belle Experiment

Mingkui Wang, Olivier Schneider, Chao Wang, Sun Hee Kim, Tara Nanut, Jun Yong Kim, Chang-Hyun Park, Seyed Sina Mirrazavi Salehian, Joo Yeon Kim, Timothy Chi Hin Liew, Yong Chan Choi, Martin Lubej, Wondwossen Wubie Eshetu, Johannes Julius Thomas Marinus Swartjes, Takayuki Yamashita
2018
Journal Articles

Abstract

We report the results of a search for the rare, purely leptonic decay B- -> mu(-)(nu) over bar (mu) performed with a 711 fb(-1) data sample that contains 772 x 10(6) B (B) over bar pairs, collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B- -> mu(-)(nu) over bar (mu)) = (6.46 +/- 2.22 +/- 1.60) x 10(-7) or a frequentist 90% confidence level interval on the B- -> mu(-)(nu) over bar (mu) branching fraction of [2.9, 10.7] x 10(-7).

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Abstract

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Related concepts (30)

Belle experiment

The Belle experiment was a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers, at the High Energy Accelerator Research Organisation (KEK) in Tsukuba, Ibaraki Prefecture, Japan. The experiment ran from 1999 to 2010. The Belle detector was located at the collision point of the asymmetric-energy electron–positron collider, KEKB.

Physics beyond the Standard Model

Physics beyond the Standard Model (BSM) refers to the theoretical developments needed to explain the deficiencies of the Standard Model, such as the inability to explain the fundamental parameters of the standard model, the strong CP problem, neutrino oscillations, matter–antimatter asymmetry, and the nature of dark matter and dark energy. Another problem lies within the mathematical framework of the Standard Model itself: the Standard Model is inconsistent with that of general relativity, and one or both theories break down under certain conditions, such as spacetime singularities like the Big Bang and black hole event horizons.

Standard deviation

In statistics, the standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range. Standard deviation may be abbreviated SD, and is most commonly represented in mathematical texts and equations by the lower case Greek letter σ (sigma), for the population standard deviation, or the Latin letter s, for the sample standard deviation.

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