Double-lepton polarization asymmetries in Λ b → Λℓ + ℓ − decay are calculated in universal extra dimension (UED) model. It is obtained that numerous double-lepton polarization asymmetries are very sensitive to the UED model and therefore can be very useful tool for establishing new physics predicted by the UED model.

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The axial-vector form factor of the nucleons is considered in the framework of hard-wall model of holographic QCD. A new interaction term between the bulk gauge and matter fields was included into the interaction Lagrangian. We obtain the axial-vector form factor of nucleons in the boundary QCD from the bulk action using AdS/CFT correspondence. The momentum square dependence of the axial-vector form factor is analysed numerically. I. INTRODUCTIONThe weak processes such as β decay n → p + e − +ν e , µ capture µ − + p = ν µ + n and so on proceed via vector and axial-vector current of the nucleons. Form factors, which describe interaction vertex in these processes, are called the axial-vector form factors of the nucleons and were studied in the field theory framework. After the appearance of the QCD models based on AdS/CFT correspondence [1][2][3][4], which were called holographic QCD or AdS/QCD models [5][6][7][8][9][10][11], these form factors were considered in the framework of these models as well. The AdS/QCD models such as hard-wall and soft-wall models were applied to the calculation of mass spectra, couplings and decay constants, form factors etc, which can be measured in the experiment [12][13][14][15][16][17][18][19][20][21]. These models * Electronic address: sh.

The exclusive B s → γl þ l − decay is analyzed in the framework of a family nonuniversal Z 0 model by calculating the differential branching ratio, double lepton polarizations, and forward-backward asymmetries. Our results are compared against those of the Standard Model. The predictions of this work are hoped to be tested in the near future at LHCb.