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M. Savci

Publications and source records attributed to M. Savci.

At least 127 records · Page 7Linked to original sources
arXiv2001

Exclusive B -> K^* l^+ l^- decay with polarized K^* and new physics effects

Using the most general, model independent effective Hamiltonian, the branching ratio of the (B -> K^* l^+ l^-) decay, when K^* meson is longitudinally or transversally polarized, is presented. The dependence of the branching ratio on the new Wilson coefficients, when K^* meson is polarized, is studied. It is observed that the branching ratio is very sensitive to the vector and tensor type interactions, which will be useful in search of new physics beyond the Standard Model.

hep-ph↗
arXiv2001

New physics effects to the lepton polarizations in the B -> K l^+ l^- decay

Using the general, model independent form of the effective Hamiltonian, the general expressions of the longitudinal, normal and transversal polarization asymmetries for (l^-) and (l^+) and combinations of them for the exclusive (B -> K l^+ l^-) decay are found. The sensitivity of lepton polarizations and their combinations on new Wilson coefficients are studied. It is found that there exist regions of Wilson coefficients for which the branching ratio coincides with the Standard Model result while the lepton polarizations differ substantially from the standard model prediction. Hence, studying lepton polarization in these regions of new Wilson coefficients can serve as a promising tool for establishing new physics beyond the Standard Model.

hep-ph↗
arXiv2001

General analysis of time evolution of decay spectrum in B^0 -> pi^+ pi^- l^+ l^-

Using the general, model independent form of effective Hamiltonian, the decay spectrum of B^0 -> pi^+ pi^- l^+ l^- decay is studied. The sensitivity of experimentally measurable asymmetries to the new Wilson coefficients and time is studied. It is observed that different asymmetries are sensitive to the new Wilson coefficients and they can serve as an efficient tool for establishing new physics beyond SM.

hep-ph↗
arXiv2001

Rare B -> K^* (nu) bar(nu) decay beyond standard model

Using the most general, model-independent form of effective Hamiltonian, the exclusive, rare $B \rar K^\ast ν\bar ν$ decay is analyzed. The sensitivity of the branching ratios and missing mass-squared spectrum to the new Wilson coefficients is discussed.

hep-ph↗
arXiv2000

General analysis of lepton polarizations in rare B -> K^* l^+ l^- decay beyond the standard model

The general analysis of lepton polarization asymmetries in rare B -> K^* l^+ l^- decay is investigated. Using the most general, model independent effective Hamiltonian, the general expressions of the longitudinal, normal and transversal polarization asymmetries for l^- and l^+ and combinations of them are presented. The dependence of lepton polarizations and their combinations on new Wilson coefficients are studied in detail. Our analysis shows that the lepton polarization asymmetries are very sensitive to the scalar and tensor type interactions, which will be very useful in looking for new physics beyond the standard model.

hep-ph↗
arXiv2000

Model-independent analysis of the exclusive semileptonic B -> pi^+ pi^- l^+ l^- decay

A model-independent analysis for the exclusive, rare B -> pi^+ pi^- l^+ l^- decay is presented. The dependence of the various physically measurable asymmetries and CP violating asymmetry on the new Wilson coefficients is studied in detail. It is observed that different measurable quantiles are very sensitive to the different new Wilson coefficients, i.e., to the existence of new physics beyond standard model.

hep-ph↗
arXiv2000

More about on the short distance contribution to the "B_c -> B_u^* gamma" decay

We calculate the transition form factor for the 'B_c -> B_u^* gamma' decay taking into account only the short distance contribution, in framework of QCD sum rules method. We observe that the transition form factor predicted by the QCD sum rules method is approximately two times larger compared to the result predicted by the Isgur, Scora, Grinstein and Wise model.

hep-ph↗
arXiv2000

The B -> X_d l^+ l^- decay in general two Higgs doublet model

The branching ratio, forward-backward asymmetry and CP violating asymmetry for (B -> X_d l^+ l^-) decay, in framework of the general two Higgs doublet model, with extra phase angle in the charged-Higgs-fermion coupling, are calculated. It is shown that studying the CP violating asymmetry is an efficient tool for establishing new physics.

hep-ph↗
arXiv2000

Fourth generation effects in rare exclusive B -> K^* l^+ l^- decay

Influence of the fourth generation, if ever exists, on the experimentally measurable quantities such as invariant dilepton mass distribution, lepton forward-backward asymmetry, and the ratio (Gamma_L/Gamma_T) of the decay widths when K* meson is longitudinally and transversally polarized, is studied. Using the experimental results on the branching ratios for the (B -> X_s) gamma and semileptonic (B -> X_c l nu) decays, the two possible solutions of the 4x4 Cabibbo-Kobayashi-Maskawa factor (V_{t's} V_{t^'b}) are obtained as a function of the t'-quark mass. It is observed that the results for the above-mentioned physical quantities are essentially different from the standard model predictions only for one solution of the CKM factor. In this case the above-mentioned physical quantities can serve as efficient tools in search of the fourth generation. The other solution yields almost identical results with the SM.

hep-ph↗
arXiv1999

Probing the sources of CP violation via B -> K^* l^+ l^- decay

The B -> K^* l^+ l^- (l = mu, tau) is analyzed in a minimally extended Standard Model in which the Wilson coefficients have new CP-odd phases. The sensitivity of the CP asymmetry and lepton polarization asymmetries to the new phases is discussed. It is found that the CP asymmetry is sensitive to the new phase in the Wilson coefficient C_7 whereas the normal lepton polarization asymmetry is sensitive to the phase in the Wilson coefficient C_(10). Additionally, the correlation between the CP and normal lepton polarization asymmetries is studied. A simultaneous measurement of these two asymmetries can be useful in search for the existence of the new sources of CP violation beyond the Standard Model.

hep-ph↗
arXiv1999

Exclusive Lambda_b -> Lambda l^+ l^- decay in two Higgs doublet model

Rare Lambda_b -> Lambda l^+ l^- decay is investigated in framework of general two Higgs doublet model, in which a new source of CP violation exists (model III). The polarization parameter, CP asymmetry and decay width are calculated. It is shown that CP asymmetry is a very sensitive tool for establishing model III.

hep-ph↗
arXiv1999

Pion--baryon coupling constants in light cone QCD sum rules

We calculate the "pi Sigma Lambda" and "pi Sigma Sigma" coupling constants in light cone QCD sum rules for the structure "sigma_{alpha beta} gamma_5 p^alpha q^beta". A comparison of our results on these coupling constants with prediction of the SU(3) symmetry is presented.

hep-ph↗
arXiv1999

The "radiative Delta -> N gamma" decay in light cone QCD

The "g_{Delta N gamma}" coupling for the "Delta -> N gamma" decay is calculated in framework of the light cone QCD sum rules and is found to be g_{Delta N gamma} = (1.6 pm 0.2) GeV^(-1). Using this value of g_{Delta N gamma} we estimate the branching ratio of the Delta^+ -> N gamma decay, which is in a very good agreement with the experimental result.

hep-ph↗
arXiv1999

Semileptonic B -> a_1 l nu decay in QCD

The form factors and the branching ratio of the "B -> a_1 l nu" decay are calculated in framework of QCD sum rules. A comparison of our results on form factors and branching ratio with the results from constituent quark model is presented.

hep-ph↗
arXiv1998

Exclusive B -> pi e^+ e^- and B -> rho e^+ e^-

We investigate the exclusive B -> pi e^+ e^- and B -> rho e^+ e^- decays in framework of the general two Higgs doublet model (model III), in which an extra phase angle in the charged--Higgs fermion coupling, i.e., a new source for CP violation exists. The CP violation for both decays are calculated and it is observed that the CP violating asymmetry in model III differs significantly than the one predicted by the standard model and model II which is a special case of model III. Furthermore, it is shown that the zero value of forward backward asymmetry A_{FB} is shifted when compared with the SM value, which can also serve as the efficiency tool for establishing new physics.

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