Leandro Da Rold

A custodial symmetry for Zbb

We show that a subgroup of the custodial symmetry O(3) that protects �ρ from radiative corrections can also protect the Zbcoupling. This allows one to build models of electroweak symmetry breaking, such as Higgsless, Little Higgs or 5D composite Higgs models, that are safe from corrections to Z → bb. We show that when this symmetry protects Zbit cannot simultaneously protect Ztand W t ¯. Therefore one can expect to measure sizable deviations from the SM predictions of these couplings at future collider experiments. We also show under what circumstances ZbRR can receive corrections in the right direction to explain the anomaly in the LEP/SLD forward-backward asymmetry A b B.

The scalar and pseudoscalar sector in a five-dimensional approach to chiral symmetry breaking

We study the scalar and pseudoscalar sector in a five-dimenional model describing chiral symmetry breaking. We calculate the scalar and pseudoscalar two-point correlator, the mass spectrum and interactions. We also obtain the scalar and pseudoscalar contributions to the coefficients of the chiral lagrangian and determine the scalar form factor of the pseudo-Goldstone bosons. Most quantities show a good agreement with QCD.

Up asymmetries from exhilarated composite flavor structures

A bstractWe present a class of warped extra dimension (composite Higgs) models which conjointly accommodates the

The Lepton Sector of a Fourth Generation

t\overline{t}

Radiative corrections in 5D and 6D expanding in winding modes

forward-backward asymmetry observed at the Tevatron and the direct CP asymmetry in singly Cabibbo suppressed D decays first reported by the LHCb collaboration. We argue that both asymmetries, if arising dominantly from new physics beyond the Standard Model, hint for a flavor paradigm within partial compositeness models in which the right-handed quarks of the first two generations are not elementary fields but rather composite objects. We show that this class of models is consistent with current data on flavor and CP violating physics, electroweak precision observables, dijet and top pair resonance searches at hadron colliders. These models have several predictions which will be tested in forthcoming experiments. The CP asymmetry in D decays is induced through an effective operator of the form

Chiral symmetry breaking from five dimensional spaces

{{\left( {\overline{u}c} \right)}_{V+A }}{{\left( {\overline{s}s} \right)}_{V+A }}

Graviton resonance phenomenology and a pseudo-Nambu-Goldstone boson Higgs at the LHC

at the charm scale, which implies a larger CP asymmetry in the D0 → K+K− rate relative the D0 → π+π− channel. This prediction is distinctive from other Standard Model or dipole-based new physics interpretation of the LHCb result. CP violation in

Wrong vertex displacements due to Lee-Wick resonances at LHC

D-\overline{D}

Phenomenology of a light gluon resonance in top-physics at Tevatron and LHC

mixing as well as an an excess of dijet production of the LHC are also predicted to be observed in a near future. A large top asymmetry originates from the exchange of an axial resonance which dominantly produces left-handed top pairs. As a result a negative contribution to the lepton-based forward-backward asymmetry in

A 750 GeV graviton and the Higgs as a pNGB

t\overline{t}