13 research outputs found
Inclusive Semi-leptonic B Decays to order 1/m_b^4
We give a systematic way to compute higher orders in the 1/m_b expansion in
inclusive semi-leptonic decays at tree level. We reproduce the known 1/m_b^3
terms and compute the 1/m_b^4 terms at tree level. The appearing
non-perturbative parameters and the impact on the determination of V_{cb} are
discussed.Comment: 23 pages, 3 figures, uses phystex.st
Complete Michel Parameter Analysis of inclusive semileptonic b \to c transition
We perform a complete "Michel parameter" analysis of all possible helicity
structures which can appear in the process . We
take into account the full set of operators parametrizing the effective
Hamiltonian and include the complete one-loop QCD corrections as well as the
non-perturbative contributions. The moments of the leptonic energy as well as
the combined moments of the hadronic energy and hadronic invariant mass are
calculated including the non-standard contributions.Comment: 22 pages, 3 figures, non-perturbative corrections adde
Minimal Flavour Violation and Beyond
Starting from the effective-theory framework for Minimal Flavour Violation,
we give a systematic definition of next-to-minimal (quark) flavour violation in
terms of a set of spurion fields exhibiting a particular hierarchy with respect
to a small (Wolfenstein-like) parameter. A few illustrative examples and their
consequences for charged and neutral decays with different quark chiralities
are worked out in some detail. Our framework can be used as a model-independent
classification scheme for the parameterization of flavour structure from
physics beyond the Standard Model.Comment: 17 pages, no figures, phenomenological discussion extended,
references adde
The Two Roads to "Intrinsic Charm" in B Decays
We describe two complementary ways to show the presence of higher order
effects in the 1/m_Q expansion for inclusive B decays that have been dubbed
"Intrinsic Charm". Apart from the lessons they can teach us about QCD's
nonperturbative dynamics their consideration is relevant for precise
extractions of |V_{cb}|: for they complement the estimate of the potential
impact of 1/m_Q^4 contributions. We draw semiquantitative conclusions for the
expected scale of Weak Annihilation in semileptonic B decays, both for its
valence and non-valence components.Comment: 17 pages, 3 figure
Model-independent Analysis of Lepton Flavour Violating Tau Decays
Many models for physics beyond the Standard Model predict lepton-flavour
violating decays of charged leptons at a level which may become observable very
soon. In the present paper we investigate the decays of a Tau into three
charged leptons in a generic way, based on effective-field-theory methods,
where the relevant operators are classified according to their chirality
structure. We work out the decay distributions and discuss phenomenological
implications.Comment: 14 pages, 10 figures, references and comments adde
Search for the lepton flavour violating decay Ï â â ÎŒ â ÎŒ + ÎŒ â
A search for the lepton flavour violating decay
is performed with the LHCb experiment. The data sample corresponds to an
integrated luminosity of of proton-proton collisions at
a centre-of-mass energy of and
at . No evidence is found
for a signal, and a limit is set at confidence level on the branching
fraction, .Comment: 20 pages, 10 figures, published as JHEP 02 (2015) 12
Inclusive Semi-leptonic B Decays to order 1/m 4 b
We give a systematic way to compute higher orders in the 1/mb expansion in inclusive semi-leptonic decays at tree level. We reproduce the known 1/m3 b terms and compute the 1/m4 b terms at tree level. The appearing non-perturbative parameters and the impact on Inclusive semi-leptonic decays are the cleanest way to access the matrix elements of the CKM matrix. In order to achieve precision in the determination of the CKM parameters a reliable theoretical framework is needed in addition to precise data. From the off-diagonal CKM matrix elements only Vus and Vcb are known very precisely from direct measurements [1], and bot