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Probing new physics in rare B and Z degree decays

Thesis/Dissertation ·
OSTI ID:5261464
The author analyzes flavor changing neutral current (FCNC) phenomena in B meson and Z boson decays. He studies the rare processes b {yields} s{gamma}, b {yields} sg, b {yields} sl{sup +}l{sup {minus}} and b {yields} s{nu}{bar {nu}} in left-right symmetric (LRS) extensions of the standard model of the electroweak interactions. The branching ratios of these processes depend upon the mass M{sub R} of the right-handed gauge boson W{sub R} and the mixing {xi} between W{sub R} and W{sub L}. Taking M{sub R} > 1.6 TeV and {xi} < 4 {times} 10{sup {minus}3}, the author concludes that the predictions of LRS models do not significantly differ from those of the standard model. However, the above bounds on M{sub R} and {xi} are plagued by major theoretical uncertainties. The author shows that, making less severe assumptions, it is possible to relax these limits. This leads to an interesting enhancement of rare B decay process in LRS models. In the second part, after discussing a new source of FCNC in super-symmetric models, the author analyzes the hadronic and leptonic flavor-changing decays of Z{degree} in N = 1 supergravity models. The author shows that the constraint from b {yields} s{gamma} implies that gluino mediated Z {yields} b{bar s} can have a branching ratio at most a few units times 10{sup {minus}8}. As for the leptonic decay Z {yields} {tau}{mu}{sup {minus}}, the author draws the same conclusion considering the constraint coming from Z {yields} {mu}{gamma}.
Research Organization:
New York Univ., NY (United States)
OSTI ID:
5261464
Country of Publication:
United States
Language:
English