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A Measurement of the Rate of Muon Capture in Hydrogen Gas andDetermination of the Proton's Induced Pseudoscalar Coupling gP

Description: This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the mu- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the mu+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be Lambda_S = 725.0 +- 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m2mu)= 7.3 +- 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.
Date: July 10, 2007
Creator: Banks, Thomas Ira
Partner: UNT Libraries Government Documents Department

Dalitz Analysis of D0 to K0(S) Pi+ Pi- and Measurement of the CKM Angle Gamma in Charged B+- Decays to D(*) K+- Decays

Description: Despite more than thirty years having elapsed since the discovery of CP violation, our understanding about the source and the nature of this phenomenon is still very limited. In the standard model of particle physics, CP violation is due to the presence of an non-irreducible weak phase in the Cabibbo-Kabayashi-Maskawa(CKM) matrix. Up to now, all the experimental results are in good agreement with the standard model. However, it is important for us to over-constrain the CKM quark-mixing matrix and explore the possibility of new physics beyond the standard model. The B meson provides an ideal place to measure CP violation due to its heavy mass and potentially large CP-violating effects. In particular, the angle {gamma} of the Unitary Triangle relating the elements of the CKM matrix is extremely crucial in terms of CP violation and constraints on the new physics models. Various methods using B{sup -} {yields} D{sup 0}K{sup -} decays have been proposed to measure based on the interference between the V{sub cb} and V{sub ub} amplitudes. Despite the simple concept, the measurement turns out to be experimentally challenging due to the small branching fraction and the small value of {tau}{sub B}, the amplitude ratio between the two contributing Feynman diagrams. In this thesis a novel technique to measure {gamma} in B{sup -} {yields} D{sup (*)} K{sup -} decay using a Dalitz plot analysis of D{sup 0} {yields} K{sub s}{pi}{sup +}{pi}{sup -} is presented. Until the turn on of LHC{sub b} [1] later in the decade, this remains the most promising method to measure {gamma}. This thesis is roughly separated into two parts. The first part involves a study of hadron spectroscopy and the Dalitz plot analysis of the D{sup 0} {yields} K{sub S}{sup 0}{pi}{sup +}{pi}{sup -}. The second part of the thesis involves the measurement of {gamma} in ...
Date: July 10, 2007
Creator: Lau, Yan-Pan & U., /Princeton
Partner: UNT Libraries Government Documents Department

Measurement of Branching Fractions and CP-Violating Asymmetries in B0 to K0K0bar and B+ to K0barK+ Decays at the BaBar Experiment

Description: Over the last few years, the B factories have established the Cabbibo-Kobayashi-Maskawa mechanism of CP violation in the Standard Model through the study of the decays of B mesons. The focus of Belle and BaBar has now expanded to the search for signatures of new physics beyond the Standard Model, particularly through examination of flavor-changing neutral-current transitions, which proceed through diagrams involving virtual loops. These decays are suppressed in the Standard Model, increasing sensitivity to new-physics effects but decreasing branching fractions. Exploiting large and growing datasets, BaBar and Belle have made many measurements in loop decays where a b quark transitions to an s quark, observing hints of possible deviations from Standard Model expectations in CP-violating measurements.
Date: July 10, 2007
Creator: Biesiada, Jedrzej & U., /Princeton
Partner: UNT Libraries Government Documents Department