Phenomenological Study Of New Physics Effects In The Angular Distribution Of (?)?D~*(?D?)?~-(??~-v_?)(?)_? Decay

As the most successful theory designed to describe the elementary particles and the funda-mental interactions,the Standard Model of particle physics includes the electromagnetic,weak and strong interactions that are familiar to us.Although the Standard Model has passed various experimental tests over the past few decades,there are still some experimental phenomena that could not be explained reasonably within it.For example.an obvious discrepancy is observed between the experimental measurements by the BaBar.Belle and LHCb collaborations and the Standard Model prediction for the ratios R(?)),hinting at possible new physics effects be-yond the Standard Model.Heavy flavor physics.especially the ?-meson physics.is of great significance in testing the Standard Model and searching for new physics.In this thesis.we have studied the semileptonic (?)?D*(?D?)?-(?)?decay within the Standard Model,and investigated possible new physics effects in the angular distribution of this decay within a model-independent low-energy effective Hamiltonian framework.While the an-gular distribution of (?)?D*(?D?)?-(?)? is very helpful for extracting information about the new physics,it cannot be measured directly.This is because the three-momentum p? of the ?lepton cannot be determined precisely due to an unobservable (?)? in the decay product of the? lepton.So.in this thesis.we constructed a measurable angular distribution by considering a cascade decay of the ? lepton.?-??-(?)?.The full process we are considering is there-fore (?)?D*(?D?)?-(??-(?)?)(?)?,which includes three final-state particles D,? and ?-with their three-momenta being all able to be measured.A complete set of observables can be constructed through the angular distribution,some of which are CP-violating.Then,adopting the most general low-energy effective Hamiltonian given at the mb scale,we have discussed the new physics effects on the angular distribution of this decay under the constraints from the current experimental data,and found that both the magnitudes and the relative phases of all the new physics parameters can be extracted by fitting to the angular distribution.For the numerical analysis,using the (?)?D*transition form factors calculated by the lattice QCD and QCD light-cone sum rules approaches,we have presented numerical results for the differential branching ratio(dBr/dq2).the longitudinal(FLD*)and the transverse(FTD*)polarization fraction of the D*meson,the leptonic forward-backward asymmetry(AFB).and the convexity parameters(CF),as well as the CP-violating observables {AT(1))?<AT(2),and<AT(3)>.It can be found that the new physics effect from tensor type is rather significant.Given that(AT(1)),(AY(2))and(AT(3)>vanish exactly in the Standard Model,a non-zero observation of these observables in experiment would be a smoking-gun signal of new physics.In conclusion,we can deepen our understanding of the R(D(*))anomaly by analyzing the angular distribution of (?)?D*(?D?)?-(??-?)(?)? decay.