2013

Ph.D

HBNI

In this thesis using the semi-leptonic decay B → K* l+ l- , it is shown how NP signal can be extracted to all orders in α(s) in perturbation theory, including ‘non-factorizable’ corrections at leading order in (Λ(QCD))/m(b) in heavy quark expansion. Relations between various hadronic form factor ratios and observables are derived independent of any Wilson coefficients, which enable the researcher to test these ratios in experiments. This thesis is divided in to six chapters. Brief introduction to the theoretical tools needed to study B physics(the standard model of electroweak interaction) is given in Chapter 1. Yukawa Lagrangian which encodes the entire flavour structure of the standard model, are discussed in this chapter. The phenomenology of B decays are described in an effective field theory approach called the Operator Product Expansion (OPE). The hadronic estimates are based on the heavy quark symmetry which is discussed at the end of the chapter. The theoretical framework of B → K* l+ l- decay is described in Chapter 2. The angular distribution of B → K* l+ l- is described in Chapter 3. There are six transversity amplitudes corresponding to each of three polarization states of K meson with two chirality of the leptonic current. A model independent framework to study new physics effects is developed in Chapter 4. The low energy approximation of various relations are discussed. It is shown that these relations can be used to test the low energy approximation of form factor calculations. A numerical analysis is presented, in comparing it with the current experimental data on the B → K* l+ l- mode. Also compared the present approach with the theoretical approach available in the literature. In this thesis the author has presented various relations among observables without involving any form factors and Wilson coefficients The violation of these relations will be a clean signals of new physics. In addition, various relations between ratios of form factors and observables that are free from any Wilson coefficients are derived.