9 research outputs found
Brisure CP/T via les produits triples dans les désintégrations des hadrons à saveur de beauté
Cette thèse est constituée de quatre articles qui ont tous été publiés. Le
sujet principal est l’étude d’asymétries de brisure CP/T via les produits triples
dans les désintégrations des hadrons contenant un quark b (mésons B ou
hypérons Ab) et ce, dans le modèle standard de la physique des particules
et au-delà.This thesis is comprised of four articles, ail of which have been published.
The main subject is the study, in and beyond the standard model of particle
physics, of CP/T-violation via triple products in decays of hadrons containing
a b quark (B mesons or Ab hyperons)
T-Violating Triple-Product Correlations in Charmless Lambda_b Decays
Using factorization, we compute, within the standard model, the T-violating
triple-product correlations in the charmless decays Lambda_b -> F_1 F_2, where
F_1 is a light spin-1/2 baryon and F_2 is a pseudoscalar (P) or vector (V)
meson. We find a large triple-product asymmetry of 18% for the decay Lambda_b
-> p K^-. However, for other classes of Lambda_b -> F_1 P decays, the asymmetry
is found to be at most at the percent level. For Lambda_b -> F_1 V decays, we
find that all triple-product asymmetries are small (at most O(1%)) for a
transversely-polarized V, and are even smaller for longitudinal polarization.
Our estimates of the nonfactorizable contributions to these decays show them to
be negligible, and we describe ways of testing this.Comment: 15 pages, LaTeX, no figure
New-Physics Effects on Triple-Product Correlations in Lambda_b Decays
We adopt an effective-lagrangian approach to compute the new-physics
contributions to T-violating triple-product correlations in charmless Lambda_b
decays. We use factorization and work to leading order in the heavy-quark
expansion. We find that the standard-model (SM) predictions for such
correlations can be significantly modified. For example, triple products which
are expected to vanish in the SM can be enormous (~50%) in the presence of new
physics. By measuring triple products in a variety of Lambda_b decays, one can
diagnose which new-physics operators are or are not present. Our general
results can be applied to any specific model of new physics by simply
calculating which operators appear in that model.Comment: 20 pages, LaTeX, no figures. Added a paragraph (+ references)
discussing nonfactorizable effects. Conclusions unchange