Oscar J. P. Eboli

Quantitative tests of color evaporation: Charmonium production

Abstract The color evaporation model simply states that charmonium production is described by the same dynamics as D D production, i.e., by the formation of a colored c c pair. Its color happens to be bleached by soft final-state interactions. We show that the model gives a complete picture of charmonium production including low-energy production by proton, photon and antiproton beams, and high-energy production at the Tevatron and HERA.

The Higgs legacy of the LHC Run I

A bstractBased on Run I data we present a comprehensive analysis of Higgs couplings. For the first time this SFitter analysis includes independent tests of the Higgs-gluon and top Yukawa couplings, Higgs decays to invisible particles, and off-shell Higgs measurements. The observed Higgs boson is fully consistent with the Standard Model, both in terms of coupling modifications and effective field theory. Based only on Higgs total rates the results using both approaches are essentially equivalent, with the exception of strong correlations in the parameter space induced by effective operators. These correlations can be controlled through additional experimental input, namely kinematic distributions. Including kinematic distributions the typical Run I reach for weakly interacting new physics now reaches 300 to 500 GeV.

Twin Higgs-boson production☆

Abstract We investigate the production of a standard Higgs boson pair in proton-proton collisions at the SSC energy. This process alloys us to study the trilinear Higgs coupling.

The Gauge-Higgs Legacy of the LHC Run I

A bstractThe effective Lagrangian expansion provides a framework to study effects of new physics at the electroweak scale. To make full use of LHC data in constraining higher-dimensional operators we need to include both the Higgs and the electroweak gauge sector in our study. We first present an analysis of the relevant di-boson production LHC results to update constraints on triple gauge boson couplings. Our bounds are several times stronger than those obtained from LEP data. Next, we show how in combination with Higgs measurements the triple gauge vertices lead to a significant improvement in the entire set of operators, including operators describing Higgs couplings.

Colorless states in perturbative QCD: Charmonium and rapidity gaps

Abstract We point out that an unorthodox way to describe the production of rapidity gaps in deep inelastic scattering, recently proposed by Buchmuller and Hebecker, suggests a description of the production of heavy quark bound states which is in agreement with data. The approach questions the conventional treatment of the color quantum number in perturbative QCD.

Probing bilinear R-parity violating supergravity at the LHC

We study the collider phenomenology of bilinear R-parity violating supergravity, the simplest effective model for supersymmetric neutrino masses accounting for the current neutrino oscillation data. At the CERN Large Hadron Collider the center-of-mass energy will be high enough to probe directly these models through the search for the superpartners of the Standard Model (SM) particles. We analyze the impact of R-parity violation on the canonical supersymmetry searches?that is, we examine how the decay of the lightest supersymmetric particle (LSP) via bilinear R-parity violating interactions degrades the average expected missing momentum of the reactions and show how this diminishes the reach in the usual channels for supersymmetry searches. However, the R-parity violating interactions lead to an enhancement of the final states containing isolated same-sign di-leptons and trileptons, compensating the reach loss in the fully inclusive channel. We show how the searches for displaced vertices associated to LSP decay substantially increase the coverage in supergravity parameter space, giving the corresponding reaches for two reference luminosities of 10 and 100 fb?1 and compare with those of the R-parity conserving minimal supergravity model.

Searching for invisibly decaying Higgs bosons at CERN LEP II

We study the potential of CERN LEP II to unravel the existence of invisibly decaying Higgs bosons, predicted in a wide class of models. We perform a model-independent analysis, focusing our attention on the final state topologies exhibiting b{bar b} or scr(l){sup +}scr(l){sup {minus}} (scr(l)={mu} or e) pairs and missing energy. We carefully evaluate the signals and backgrounds, choosing appropriate cuts to enhance the discovery limits. Our results demonstrate that LEP II is capable of discovering such a Higgs boson for a wide range of masses and couplings. {copyright} {ital 1997} {ital The American Physical Society}

Bounds on Higgs and Gauge-Boson Interactions from LEP2 Data

Inst. de Fis. Teorica Universidade Estadual Paulista, Rua Pamplona 145, 01405-900 Sao Paulo

Bounds on effective interactions from the reaction e+e−→γγ at LEP

Abstract We establish bounds on the mass scale of effective interactions between fermions and photons using the OPAL data for the reaction e + e − →γγ at √ s =91.22 GeV.

Anomaly mediated supersymmetry breaking without R parity

Abstract We analyze the low energy features of a supersymmetric standard model where the anomaly-induced contributions to the soft parameters are dominant in a scenario with bilinear R -parity violation. This class of models leads to mixings between the standard model particles and supersymmetric ones which change the low energy phenomenology and searches for supersymmetry. In addition, R -parity violation interactions give rise to small neutrino masses which we show to be consistent with the present observations.