6,063 research outputs found
B semileptonic moments at NNLO
The calculation of the moments in inclusive B meson semileptonic decays is
upgraded to O(alphas^2). The first three moments of the lepton energy and
invariant hadronic mass distributions are computed for arbitrary cuts on the
lepton energy and in various renormalization schemes, finding in general small
deviations from the O(alphas^2 beta0) calculation. I also review the relation
between MSbar and kinetic heavy quark masses.Comment: 28 pages, 9 figure
Precision Electroweak Measurements Circa 2002
Present global fits to electroweak data are characterized by two results that
differ from Standard Model expectations by about 3 sigma, the NuTeV measurement
of sin^2theta_W and the FB b quark asymmetries measured at LEP. I review
possible SM and new physics explanations of these anomalies and the
implications for the indirect determination of the Higgs mass.Comment: 6 pages, 2 figures, talk at ICHEP, Amsterdam, 24-31 July 200
Semileptonic and radiative B decays circa 2005
I briefly review the theoretical status of semileptonic and radiative B
decays in 2005.Comment: 6 pages, 1 fig, review talk at Beauty 2005, Assisi, June 20-24 200
Normalizing inclusive rare B decays
The inclusive semileptonic branching ratio is often employed to normalize
other inclusive B decays. Using recent determinations of the non-perturbative
parameters of the Operator Product Expansion we compute the normalization
factor for the branching ratio of B->X_s gamma and find a few percent
enhancement with respect to previous determinations.Comment: 11 pages, 1 fig; minor numerical changes, text improved, matches
version to appear in PL
Towards a constructive simplicial model of Univalent Foundations
We provide a partial solution to the problem of defining a constructive
version of Voevodsky's simplicial model of univalent foundations. For this, we
prove constructive counterparts of the necessary results of simplicial homotopy
theory, building on the constructive version of the Kan-Quillen model structure
established by the second-named author. In particular, we show that dependent
products along fibrations with cofibrant domains preserve fibrations, establish
the weak equivalence extension property for weak equivalences between
fibrations with cofibrant domain and define a univalent classifying fibration
for small fibrations between bifibrant objects. These results allow us to
define a comprehension category supporting identity types, -types,
-types and a univalent universe, leaving only a coherence question to be
addressed.Comment: v3: changed the definition of the type Weq(U) of weak equivalences to
fix a problem with constructivity. Other Minor changes. 31 page
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