arXiv subjects

J. R. Pelaez

Publications and source records attributed to J. R. Pelaez.

135 records · Page 8Linked to original sources

arXiv1997

Strong WW scattering and resonances at LHC

The low energy dynamics of the general strongly interacting symmetry breaking sector can be easily described using effective chiral Lagrangians. Indeed, the enhancement in WW scattering at LHC, that would imply the existence of such an strong interaction, can be described with just two chiral parameters. These techniques have been shown to reproduce remarkably well the low-energy pion-pion scattering data, which follows a similar formalism. In this work we first review the LHC sensitivity to those two chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later it is shown how we can predict the general resonance spectrum of the strongly interacting symmetry breaking sector. For that purpose, we use the inverse amplitude method which is also very successful reproducing the lightest hadronic resonances from data in the low-energy non resonant region. We thus present an study of the regions in parameter space where one, two or no resonances may appear.

hep-ph↗

arXiv1996

Resonance Spectrum of the strongly interacting Symmetry Breaking Sector

Within the chiral lagrangian formalism it is possible to describe the general strongly coupled Symmetry Breaking Sector in terms of a few parameters. Based on a dispersive approach we have studied the resonance spectrum up to 3 TeV in the chiral parameter space. This procedure could also be useful to extract the higher energy resonant behavior from low-energy collider data. It is also shown how the method reproduces the correct pole structure of resonances as well as other analytic features. The results also hint at a possible excluded region of parameter space.

hep-ph↗

arXiv1996

Strong WW Scattering. Chiral Lagrangians, Unitarity and Resonances

Chiral lagrangians provide a model independent description of the strongly interacting symmetry breaking sector. In this work it is first reviewed the LHC sensitivity to the chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later it is shown how to reproduce or predict the resonance spectrum by means of dispersion theory and the inverse amplitude method. We present a parameter space scan that covers many different strong WW scattering scenarios.

hep-ph↗

arXiv1996

Higgs Physics in the Large N limit

In this paper we study the large N limit of the Standard Model Higgs sector with $Nλ$, $Ng^2$ and $Ng'^2$ constant and $N$ being the number of would-be Goldstone bosons. Despite the simplicity of this method at leading order, its results satisfy simultaneously important requirements such as unitarity and the low-energy theorems in contrast with other more conventional approaches. Moreover, it is fully compatible with the Equivalence Theorem and it yields a consistent description of the Higgs boson mass and width. Finally we have also included a phenomenological discussion concerning the applications of this method to the LHC.

hep-ph↗

arXiv1995

Learning about the strongly interacting symmetry breaking sector at LHC

In the present work we study the predictions for $WZ$ and $ZZ$ production at LHC with the Electroweak Chiral Lagrangian (EChL) approach. Our analysis will be focused on the less favored case from the experimental point of view, in which the predictions for the gauge bosons scattering amplitudes are considered in the low energy range where, by construction of the low energy approach, they reveal no resonant behavior. The study includes the complete set of amplitudes for all the polarization states of the initial and/or final gauge bosons and makes no use of the Equivalence Theorem. We express the results in terms of the range of values of the chiral parameters that will be accessible at LHC.

hep-ph↗

arXiv1994

The Applicability of the Equivalence Theorem in $χPT$

We have explicitely calculated the tree level elastic scattering cross sections of two longitudinal gauge bosons, up to four derivatives in the chiral expansion both with and without using the Equivalence Theorem (ET). The numerical results show the existence of new and severe restrictions in the ET energy applicability range, as it was stated in our recent derivation, which we also review here, of the precise ET version in the Chiral Lagrangian description of the Standard Model Symmetry Breaking Sector.

hep-ph↗

arXiv1994

On the Equivalence Theorem in the $χPT$ Description of the Symmetry Breaking Sector of the Standard Model

We develop an alternative formulation of the symmetry breaking sector of the Standard Model as a gauged non-linear sigma model (NLSM) following the philosophy of the Chiral lagrangian approach, which is the only compatible with all the experimental and theoretical constraints. We derive the BRS symmetry of the model and the corresponding quantum lagrangian, which is a generalization of the standard Faddeev-Popov method, in a way which is covariant with respect to the reparametrizations of the coset space of the NLSM. Then we use the BRS invariance of the quantum lagrangian to state the Equivalence Theorem for the renormalized $S$-matrix elements calculated as a chiral expansion.

hep-ph↗

arXiv1994

The Equivalence Theorem for Chiral Lagrangians

In this work we derive the version of the Equivalence Theorem that applies when the symmetry breaking sector of the Standard Model is described by a general chiral lagrangian. The demonstration is valid for renormalized fields for any value of the gauge parameter (in $R_ξ$ gauges) and any parametrization of the coset space. It is based in the absence of gauge anomalies which makes it possible to build an (anti)-BRS invariant chiral lagrangian in terms of the renormalized fields and therefore to use the corresponding Ward identities to obtain the theorem.

hep-ph↗

arXiv1993

A global fit of $ππ$ and $πK$ elastic scattering in ChPT with dispersion relations

We apply the one-loop results of the $SU(3)_L\times SU(3)_R$ ChPT suplemented with the inverse amplitude method to fit the available experimental data on $ππ$ and $πK$ scattering. With esentially only three parameters we describe accurately data corresponding to six different channels, namely $(I,J)=(0,0), (2,0), (1,1), (1/2,0), (3/2,0)$ and $(1/2,1)$. In addition we reproduce the first resonances of the $(1,1)$ and $(1/2,1)$ channel with the right mass corresponding to the $ρ$ and the $K^*(892)$ particles.

hep-ph↗