Vector triplets at the LHC

Several popular extensions of the Standard Model predict extra vector fields that transform as triplets under the gauge group SU(2)_L. These multiplets contain Z' and W' bosons, with masses and couplings related by gauge invariance. We review some model-independent results about these new vector bosons, with emphasis on di-lepton and lepton-plus-missing-energy signals at the LHC.Comment: LaTex 5 pages. Talk by M. Perez-Victoria at LHCP 2013, Barcelona, Spain, May 13-18, 2013. New reference adde

Differential Renormalization of Gauge Theories

The scope of constrained differential renormalization is to provide renormalized expressions for Feynman graphs, preserving at the same time the Ward identities of the theory. It has been shown recently that this can be done consistently at least to one loop for abelian and non-abelian gauge theories. We briefly review these results, evaluate as an example the gluon selfenergy in both coordinate and momentum space, and comment on anomalies.Comment: LaTex, 8 pages with 1 ps figures, talk given at the Zeuthen Workshop on Elementary Particle Physics "Loops and Legs in Gauge Theories", Rheinsberg, Germany, April 19-24, 1998, to appear in Acta Physica Polonica

Asymmetries in t tbar production: LHC versus Tevatron

The measurement of a charge asymmetry in t tbar production at LHC constitutes more than an independent confirmation of the forward-backward asymmetry found at Tevatron. Indeed, both measurements together can be used to identify the source of the asymmetry. This is demonstrated for the case of new Z', W' vector bosons and colour-sextet and triplet scalars, exchanged in t, u channels respectively, and a very heavy axigluon in the s channel.Comment: LaTeX 5 pages. Updated with discussion on implications of summer results. Final version to appear in PR

Holographic renormalisation group flows and renormalisation from a Wilsonian perspective

From the Wilsonian point of view, renormalisable theories are understood as submanifolds in theory space emanating from a particular fixed point under renormalisation group evolution. We show how this picture precisely applies to their gravity duals. We investigate the Hamilton-Jacobi equation satisfied by the Wilson action and find the corresponding fixed points and their eigendeformations, which have a diagonal evolution close to the fixed points. The relevant eigendeformations are used to construct renormalised theories. We explore the relation of this formalism with holographic renormalisation. We also discuss different renormalisation schemes and show that the solutions to the gravity equations of motion can be used as renormalised couplings that parametrise the renormalised theories. This provides a transparent connection between holographic renormalisation group flows in the Wilsonian and non-Wilsonian approaches. The general results are illustrated by explicit calculations in an interacting scalar theory in AdS space.Comment: 63 pages. Minor changes and references added. Matches JHEP versio

Physics of Brane Kinetic Terms

Models with extra dimensions may give new effects visible at future experiments. In these models, bulk fields can develop localized corrections to their kinetic terms which can modify the phenomenological predictions in a sizeable way. We review the case in which both gauge bosons and fermions propagate in the bulk, and discuss the limits on the parameter space arising from electroweak precision data.Comment: Presented at Matter To The Deepest: Recent Developments In Physics of Fundamental Interactions, XXVII International Conference of Theoretical Physics, Ustron 15-21 September 2003, Polan

Observable contributions of new exotic quarks to quark mixing

Models with new vector-like quarks can produce observable quark mixing effects which are forbidden in the Standard Model. We classify all such models and write down the effective Lagrangian that results from integrating out the new quarks. We study the relations between neutral and charged currents and discuss how to distinguish among the different possibilities.Comment: 15 pages, 1 figure, typos corrected, version to appear in JHE

Bulk fields with brane terms

In theories with branes, bulk fields get in general divergent corrections localized on these defects. Hence, the corresponding brane terms are renormalized and should be included in the effective theory from the very beginning. We review the phenomenology associated to brane kinetic terms for different spins and backgrounds, and point out that renormalization is required already at the classical level.Comment: Presented at HEP2003, International Europhysics Conference on High Energy Physics (July 17-23, 2003) Aachen, German