Search for WW and WZ Resonances Decaying to Electron, Missing ET, and Two Jets in pp̅ Collisions at √s=1.96 TeV.

Using data from 2.9  fb-1 of integrated luminosity collected with the CDF II detector at the Tevatron, we search for resonances decaying into a pair of on-shell gauge bosons, WW or WZ, where one W decays into an electron and a neutrino, and the other boson decays into two jets. We observed no statistically significant excess above the expected standard model background, and we set cross section limits at 95% confidence level on G* (Randall-Sundrum graviton), Z′, and W′ bosons. By comparing these limits to theoretical cross sections, mass exclusion regions for the three particles are derived. The mass exclusion regions for Z′ and W′ are further evaluated as a function of their gauge coupling strength.

Search for WW and WZ Resonances Decaying to Electron, Missing ET, and Two Jets in pp̅ Collisions at √s=1.96 TeV.

Using data from 2.9/fb of integrated luminosity collected with the CDF II detector at the Tevatron, we search for resonances decaying into a pair of on-shell gauge bosons, WW or WZ, where one W decays into an electron and a neutrino, and the other boson decays into two jets. We observed no statistically significant excess above the expected standard model background, and we set cross section limits at 95% confidence level on G*(Randall-Sundrum graviton), Z', and W' bosons. By comparing these limits to theoretical cross sections, mass exclusion regions for the three particles are derived. The mass exclusion regions for Z' and W' are further evaluated as a function of their gauge coupling strength.

Alternative search strategies for a BSM resonance fitting the ATLAS diboson excess

We study an s-channel resonance R as a viable candidate to fit the diboson excess reported by ATLAS. We compute the contribution of the similar to 2 TeV resonance R to semileptonic and leptonic final states at the 13 TeV LHC. To explain the absence of an excess in the semileptonic channel, we explore the possibility where the particle R decays to additional light scalars X, X or X, Y. A modified analysis strategy has been proposed to study the three-particle final state of the resonance decay and to identify decay channels of X. Associated production of R with gauge bosons has been studied in detail to identify the production mechanism of R. We construct comprehensive categories for vector and scalar beyond-standard-model particles which may play the role of particles R, X, Y and find alternate channels to fix the new couplings and search for these particles.

Is General Relativity a simplified theory?

IARD 8th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields - Galileo Galilei Inst Theoret Phys (GGI), Florence, ITALY - MAY 29-JUN 01, 2012. Edited by:Horowitz, LP

A study of W boson properties with four-jet W^+W^- events at LEP

In this thesis I present a study of W pair production in e⁺e^- annihilation using fully hadronic W⁺W^- events. Data collected by the L3 detector at LEP in 1996-1998, at collision center-of-mass energies between 161 and 189 GeV, was used in my analysis.

Analysis of the total and differential W⁺W^- cross sections with the resulting sample of 1,932 W⁺W^- → qqqq event candidates allowed me to make precision measurements of a number of properties of the W boson. I combined my measurements with those using other W⁺W^- final states to obtain stringent constraints on the W boson's couplings to fermions, other gauge bosons, and scalar Higgs field by measuring the total e⁺e^- → W⁺W^- cross section and its energy dependence

σ(e⁺e^- → W⁺W^-) =

{2.68^+0.98_-0.67(stat.)± 0.14(syst.) pb, √s = 161.34 GeV

{12.04^+1.38_-1.29(stat.)± 0.23(syst.) pb, √s = 172.13 GeV

{16.45 ± 0.67(stat.) ± 0.26(syst.) pb, √s = 182.68 GeV

{16.28 ± 0.38(stat.) ± 0.26(syst.) pb, √s = 188.64 GeV

the fraction of W bosons decaying into hadrons

invisible non-SM width of the W boson

the mass of the W boson

the total width of the W boson

the anomalous triple gauge boson couplings of the W

Δg^Z₁ = 0.16^+0.13_-0.20(stat.) ± 0.11(syst.)

Δk_γ = 0.26^+0.24_-0.33(stat.) ± 0.16(syst.)

λ_γ = 0.18^+0.13_-0.20(stat.) ± 0.11(syst.)

No significant deviations from Standard Model predictions were found in any of the measurements.

Extraction of CP Properties of the H(125) Boson Discovered in Proton-Proton Collisions at sqrt(s) = 7 and 8 TeV with the CMS Detector at the LHC

In this thesis we build a novel analysis framework to perform the direct extraction of all possible effective Higgs boson couplings to the neutral electroweak gauge bosons in the H → ZZ^(*) → 4l channel also referred to as the golden channel. We use analytic expressions of the full decay differential cross sections for the H → VV' → 4l process, and the dominant irreducible standard model qq ̄ → 4l background where 4l = 2e2μ,4e,4μ. Detector effects are included through an explicit convolution of these analytic expressions with transfer functions that model the detector responses as well as acceptance and efficiency effects. Using the full set of decay observables, we construct an unbinned 8-dimensional detector level likelihood function which is con- tinuous in the effective couplings, and includes systematics. All potential anomalous couplings of HVV' where V = Z,γ are considered, allowing for general CP even/odd admixtures and any possible phases. We measure the CP-odd mixing between the tree-level HZZ coupling and higher order CP-odd couplings to be compatible with zero, and in the range [−0.40, 0.43], and the mixing between HZZ tree-level coupling and higher order CP -even coupling to be in the ranges [−0.66, −0.57] ∪ [−0.15, 1.00]; namely compatible with a standard model Higgs. We discuss the expected precision in determining the various HVV' couplings in future LHC runs. A powerful and at first glance surprising prediction of the analysis is that with 100-400 fb^-1, the golden channel will be able to start probing the couplings of the Higgs boson to diphotons in the 4l channel. We discuss the implications and further optimization of the methods for the next LHC runs.

The Search for New Resonances in Strong Symmetry Breaking Scenarios with the ATLAS Detector

Utilisant les plus récentes données recueillies par le détecteur ATLAS lors de collisions pp à 7 et 8 TeV au LHC, cette thèse établira des contraintes sévères sur une multitude de modèles allant au-delà du modèle standard (MS) de la physique des particules. Plus particulièrement, deux types de particules hypothétiques, existant dans divers modèles théoriques et qui ne sont pas présentes dans le MS, seront étudiés et sondés. Le premier type étudié sera les quarks-vectoriels (QV) produits lors de collisions pp par l’entremise de couplages électrofaibles avec les quarks légers u et d. On recherchera ces QV lorsqu’ils se désintègrent en un boson W ou Z, et un quark léger. Des arguments théoriques établissent que sous certaines conditions raisonnables la production simple dominerait la production en paires des QV. La topologie particulière des évènements en production simple des QV permettra alors la mise en oeuvre de techniques d’optimisation efficaces pour leur extraction des bruits de fond électrofaibles. Le deuxième type de particules recherché sera celles qui se désintègrent en WZ lorsque ces bosons de jauges W, et Z se désintègrent leptoniquement. Les états finaux détectés par ATLAS seront par conséquent des évènements ayant trois leptons et de l’énergie transverse manquante. La distribution de la masse invariante de ces objets sera alors examinée pour déterminer la présence ou non de nouvelles résonances qui se manifesterait par un excès localisé. Malgré le fait qu’à première vue ces deux nouveaux types de particules n’ont que très peu en commun, ils ont en réalité tous deux un lien étroit avec la brisure de symétrie électrofaible. Dans plusieurs modèles théoriques, l’existence hypothétique des QV est proposé pour annuler les contributions du quark top aux corrections radiatives de la masse du Higgs du MS. Parallèlement, d’autres modèles prédisent quant à eux des résonances en WZ tout en suggérant que le Higgs est une particule composite, chambardant ainsi tout le sector Higgs du MS. Ainsi, les deux analyses présentées dans cette thèse ont un lien fondamental avec la nature même du Higgs, élargissant par le fait même nos connaissances sur l’origine de la masse intrinsèque des particules. En fin de compte, les deux analyses n’ont pas observé d’excès significatif dans leurs régions de signal respectives, ce qui permet d’établir des limites sur la section efficace de production en fonction de la masse des résonances.

Scrutinizing the ZW(+)W(-) vertex at the Large Hadron Collider at 7 TeV

We analyze the potential of the CERN Large Hadron Collider running at 7 TeV to search for deviations from the Standard Model predictions for the triple gauge boson coupling ZW(+)W(-) assuming an integrated luminosity of 1 fb(-1). We show that the study of W(+)W(-) and W(+/-)Z productions, followed by the leptonic decay of the weak gauge bosons can improve the present sensitivity on the anomalous couplings Delta g(1)(Z), Delta kappa(Z), lambda(Z), g(4)(Z), and (lambda) over bar (Z) at the 2 sigma level. (C) 2010 Elsevier B.V. All rights reserved.

Chargino and neutralino production in the 3-3-1 supersymmetric model in e(-)e(-) scattering

The goal of this article is to derive the Feynman rules involving single charginos, neutralinos, double charged gauge bosons, and sleptons in a 3-3-1 supersymmetric model. Using these Feynman rules we calculate the production of double charged charginos with neutralinos and also the production of a pair of single charged charginos, both in an electron-electron linear collider.

Probing intermediate mass Higgs interactions at the CERN large hadron collider

We analyze the potentiality of the CERN Large Hadron Collider to probe the Higgs boson couplings to the electroweak gauge bosons. We parametrize the possible deviations of these couplings due to new physics in a model independent way, using the most general dimension-six effective lagrangian where the SU(2)(L) x U(1)(Y) is realized linearly. For intermediate Higgs masses, the decay channel into two photons is the most important one for Higgs searches at the LHC, We study the effects of these new interactions on the Higgs production mechanism and its subsequent decay into two photons. We show that the LHC will be sensitive to new physics scales beyond the present limits extracted from the LEP and Tevatron physics. (C) 2000 Elsevier B.V. B,V, All rights reserved.

Doubly charged Higgs from e-gamma scattering in the 3-3-1 Model

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New signature for color octet pseudoscalars at the CERN LHC

Color octet (pseudo)scalars, if they exist, will be copiously produced at the CERN Large Hadron Collider (LHC). However, their detection can become a very challenging task. In particular, if their decay into a pair of top quarks is kinematically forbidden, the main decay channel would be into two jets, with a very large background. In this brief report we explore the possibility of using anomaly-induced decays of the color octet pseudoscalars into gauge bosons to find them at the LHC.

Radion-Higgs mixing effects on bounds from LHC Higgs boson searches

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Search for resonances in the dilepton mass distribution in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

TRIPLE-VECTOR-BOSON PROCESSES IN GAMMA-GAMMA COLLIDERS

We study the production of three gauge bosons (W(+)W(-)Z(0) and W(+)W(-)gamma) at the next generation of linear e(+)e(-) colliders operating in the yy mode. We analyze the total cross sections as well as several kinematical distributions of the final state particles. We find out that a linear e(+)e(-) machine operating in the rr mode will produce 5-10 times more three-gauge-boson states compared to the standard e(+)e(-) mode at high energies.