Search for Pure Leptonic B Decays at ATLAS and CMS

The rare decays $B_{s,d}^0 \to \mu^+\mu^-$ are important probes for new physics beyond the Standard Model. These decays are subjects of studies at the LHC. The ATLAS and CMS collaborations have analyzed the proton-proton collisions data at 7 TeV centre-of-mass energy collected in the year 2011. They have established upper limits on the branching fractions of the two decays. This paper presents a report.Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 201

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

Measurement of the Reference Channel B±→J/ψK±B^{\pm} \to J/\psi K^{\pm} for the Rare Decay Bs0→μ+μ−B_{s}^{0} \to \mu^{+}\mu^{-} with the ATLAS Experiment

The ATLAS experiment is one of the four major experiments at the Large Hadron Collider (LHC) of CERN, Geneva. The experiment addresses the open questions of particle physics. The decay of the $B_{s}^{0}$ meson to two muons is strongly suppressed in the Standard Model (SM). It is a rare decay with an expected branching fraction of $3.56\times10^{-9}$. The $B_{s}^{0} \to \mu^{+}\mu^{-}$ branching fraction is measured relative to a reference channel, $B^{\pm} \to J/\psi K^{\pm}$. The subject of this thesis is the measurement of the $B^{\pm}$ yield. The analysis uses $4.9\,fb^{-1}$ of ATLAS data collected in the year 2011 at $7\,TeV$ center-of-mass energy. The $B^{\pm}$ candidate selection is performed using a multivariate (MVA) technique. The yield is estimated using a two-dimensional unbinned maximum likelihood fit that accounts for the per-event uncertainties. The result is used for the computation of the upper limit on the $B_{s}^{0} \to \mu^{+}\mu^{-}$ branching fraction published by the ATLAS collaboration [1,2]

Measurement of the reference channel B+/- -> J/psi K+/- for the rare decay Bs -> mu+mu- with the ATLAS experiment

Das ATLAS Experiment ist eines der vier großen Experimente des Large Hadron Collider (LHC) am CERN, Genf. Mit diesem Experiment sollen die noch offenen Fragen der Teilchenphysik geklärt werden. Der Zerfall des Bs Mesons in zwei Myonen ist ein stark unterdrückter Zerfallskanal des Standard Modells (SM). Es ist ein seltener Zerfall mit einem erwartetem Verzweigungsverhältnis von 3.56 x 10^-9. Das Bs -> mu+mu- -Verzweigungsverhältnis wird relativ zum Referenzkanal B+/- -> J/psi K+/- gemessen. Das Thema diese Arbeit ist die Messung der B+/- -Ausbeute. Die Grundlage der Analyse sind 4.9/fb der ATLAS Daten, welche im Jahr 2011 bei einer Schwerpunktsenergie von 7 TeV aufgenommen wurden. Die Auswahl der B+/- -Ereignisse wurde unter Verwendung einer multivariaten Datenanalyse (MVA) durchgeführt. Die Ausbeute wird mittels eines zweidimensionalen ungebinten Maximum-Likelihood-Fits abgeschätzt, welcher die Pro-Ereignis-Unsicherheiten berücksichtigt. Mit Hilfe der Ergebnisse wird die obere Grenze auf das Bs -> mu+mu- -Verzweigungsverhältnis berechnet, welche von der ATLAS-Kollaboration veröffentlicht wurde [1,2].The ATLAS experiment is one of the four major experiments at the Large Hadron Collider (LHC) of CERN, Geneva. The experiment addresses the open questions of particle physics. The decay of the Bs meson to two muons is strongly suppressed in the Standard Model (SM). It is a rare decay with an expected branching fraction of 3.56 x 10^-9. The Bs -> mu+mu- branching fraction is measured relative to a reference channel, B+/- -> J/psi K+/-. The subject of this thesis is the measurement of the B+/- yield. The analysis uses 4.9/fb of ATLAS data collected in the year 2011 at 7 TeV center-of-mass energy. The B+/- candidate selection is performed using a multivariate (MVA) technique. The yield is estimated using a two-dimensional unbinned maximum likelihood fit that accounts for the per-event uncertainties. The result is used for the computation of the upper limit on the Bs -> mu+mu- branching fraction published by the ATLAS collaboration [1,2]