B → πlν decay is studied in the effective theory of heavy quark with infinite mass limit. The leading order heavy flavor-spin independent universal wave functions which parameterize the relevant matrix elements are evaluated via light cone sum rule method in the effective theory. The important quark mixing matrix element |V ub | is then extracted via B → πlν decay mode.

Introduction. Charged mesons formed from a quark and an anti-quark can decay to a charged lepton and a neutrino when these objects annihilate via a virtual W boson [1]. Fig. 1 illustrates this process for the purely leptonic decay of a D + meson.

We have recently presented the complete O(αs) corrections to the semileptonic decay width of the b quark at maximal recoil. Here we discuss various technical aspects of that calculation and further applications of similar methods. In particular, we describe an expansion which facilitates the phase space integrations and the treatment of the mixed real–virtual corrections, for which Taylor expan...

Flavor changing interactions of the gluino allow the b quark to decay into the strange quark plus a gluino pair if the gluino is in the ultra low mass window below 1 GeV. In this case the enhancement of the nonleptonic b decay could explain the anomalous semileptonic branching ratio. 14.80.Ly, 13.25.+m, 11.30.Pb Typeset using REVTEX

We study the semileptonic transitions Bc → ηc, J/ψ, D, D∗, B, B∗, Bs, B∗ s in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/ψ decay, lattice and QCD sum rule results on leptonic Bc decay, and on radiative ηc transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic Bc-transitions and give predictions...

In this talk I review the history of models of strong decays, from the original model through applications to charmonium, light and charmed mesons, glueballs and hybrids. Our current rather limited understanding of the QCD mechanism of strong decays is stressed. Regarding current and future applications of strong decay models, we note that in certain channels the very strong coupling predicted ...

In quark modelsà la Bakamjian and Thomas, that yield covariance and Isgur-Wise scaling of form factors in the heavy quark limit, we compute the decay constants f (n) and f (n) 1/2 of S-wave and P-wave mesons composed of heavy and light quarks. Heavy quark limit scaling √ M f = Cst. is obtained, and it is shown that this class of models satisfies the sum rules involving decay constants and Isgur...

The calculation of the partial width rare t-quark decay into Upsilon-meson, W-boson and b-quark (t -> \Upsilon W b) is presented. branching ratio equals Br(t Upsilon = 1.3 * 10^{-5} that make possible searches for this $t$-quark at LHC.