Neutral Higgs-Boson Pair Production at Hadron Colliders: QCD Corrections

Neutral Higgs-boson pair production provides the possibility of studying the trilinear Higgs couplings at future high-energy colliders. We present the QCD corrections to the gluon-initiated processes in the limit of a heavy top quark in the loops and the Drell-Yan-like pair production of scalar and pseudoscalar Higgs particles. The pp cross sections are discussed for LHC energies within the Standard Model and its minimal supersymmetric extension. The QCD corrections are large, enhancing the total cross sections significantly.Comment: 26 pages, latex, 9 ps figure

Standard Model Higgs-Boson Branching Ratios with Uncertainties

We present an update of the branching ratios for Higgs-boson decays in the Standard Model. We list results for all relevant branching ratios together with corresponding uncertainties resulting from input parameters and missing higher-order corrections. As sources of parametric uncertainties we include the masses of the charm, bottom, and top quarks as well as the QCD coupling constant. We compare our results with other predictions in the literature.Comment: 32 pages, 4 figures, contribution to LHC Higgs Cross Section Working Group https://twiki.cern.ch/twiki/bin/view/LHCPhysics/CrossSections, theoretical uncertainties for H->\mu\mu{} added, version to appear in European Physical Journal

W^+- H^-+ Associated Production at the Large Hadron Collider

We study the production of a charged Higgs boson in association with a W boson at the CERN Large Hadron Collider in the context of the minimal supersymmetric extension of the standard model. This production mechanism is particularly promising if the charged Higgs boson is too heavy to be generated by top-quark decay. We compare the contributions due to b b-bar annihilation at the tree level and gg fusion, which proceeds at one loop. Apart from the total cross section, we also consider distributions in transverse momentum and rapidity. We also assess the viability of W^+- H^-+ associated production at the Fermilab Tevatron after the installation of the Main Injector and the Recycler.Comment: 16 pages (Latex), 8 figures (Postscript

Scalar Particle Contribution to Higgs Production via Gluon Fusion at NLO

We consider the gluon fusion production cross section of a scalar Higgs boson in models where fermion and scalar massive colored particles are present. We report analytic expressions for the matrix elements of $gg\to Hg$, $q\bar{q}\to Hg$, and $qg\to Hq$ processes completing the calculation of the NLO QCD corrections in these extended scenarios. The formulas are written in a complete general case, allowing a flexible use for different theoretical models. Applications of our results to two different models are presented: i) a model in which the SM Higgs sector is augmented by a weak doublet scalar in the $SU(N_c)$ adjoint representation. ii) The MSSM, in the limit of neglecting the gluino contribution to the cross section.Comment: 20 pages, 5 figures. Minor changes. Refs. adde

Rompimiento de la Simetria Electrodebil y la Fisica del Higgs: Conceptos Basicos

Presentamos una introduccion a los conceptos basicos del rompimiento de la simetria electrodebil y la fisica del Higgs dentro del Modelo Estandar y sus extensiones supersimetricas. Se presenta tambien una breve perspectiva general de mecanismos alternativos del rompimiento de la simetria. Ademas de las bases teoricas, se discute el estado actual de la fisica experimental del Higgs y sus implicaciones para futuros experimentos en el LHC y en colisionadores lineales e+e-.Comment: Spanish text, including full English translation. Published in the Proceedings of the XI Mexican School on Particles and Fields, Xalapa, Veracruz, Mexic

Composite Higgs Search at the LHC

The Higgs boson production cross-sections and decay rates depend, within the Standard Model (SM), on a single unknown parameter, the Higgs mass. In composite Higgs models where the Higgs boson emerges as a pseudo-Goldstone boson from a strongly-interacting sector, additional parameters control the Higgs properties which then deviate from the SM ones. These deviations modify the LEP and Tevatron exclusion bounds and significantly affect the searches for the Higgs boson at the LHC. In some cases, all the Higgs couplings are reduced, which results in deterioration of the Higgs searches but the deviations of the Higgs couplings can also allow for an enhancement of the gluon-fusion production channel, leading to higher statistical significances. The search in the H to gamma gamma channel can also be substantially improved due to an enhancement of the branching fraction for the decay of the Higgs boson into a pair of photons.Comment: 32 pages, 16 figure

The Higgs - photon - Z boson coupling revisited

We analyze the coupling of CP-even and CP-odd Higgs bosons to a photon and a Z boson in extensions of the Standard Model. In particular, we study in detail the effect of charged Higgs bosons in two-Higgs doublet models, and the contribution of SUSY particle loops in the minimal supersymmetric extension of the Standard Model. The Higgs-$\gamma Z$ coupling can be measured in the decay $Z \to \gamma$+Higgs at $e^+e^-$ colliders running on the Z resonance, or in the reverse process Higgs $\to Z \gamma$ with the Higgs boson produced at LHC. We show that a measurement of this coupling with a precision at the percent level, which could be the case at future $e^+e^-$ colliders, would allow to distinguish between the lightest SUSY and standard Higgs bosons in large areas of the parameter space.Comment: 18 pages LaTex + 7 figures (ps). Typo corrected in eq.(5

Testing the Higgs boson gluonic couplings at LHC

We study Higgs + jet production at hadron colliders in order to look for new physics residual effects possibly described by the $dim=6$ operators {\O}_{GG} and {\widetilde\O}_{GG} which induce anomalous $Hgg$ and $Hggg$ couplings. Two ways for constraining these operators at LHC may be ~useful. The first is based on the total Higgs boson production rate induced by gluon-gluon fusion, in which the main cause of limitations are due to theoretical uncertainties leading to sensitivities of $|d_G|\simeq 3.\times 10^{-4}$ and $|\widetilde{d}_G|\simeq 1.4\times 10^{-3}$ for the corresponding anomalous couplings, in the mass range 100 GeV \lsim \mh \lsim 2~00 GeV. These results imply sensitivity to new physics scales of 51 and 24 TeV respectively. The second way investigated here concerns the shape of the Higgs transverse momentum; for which the theoretical uncertainties are less severe and the limitations are mainly induced by statistics. A simple analysis, based on the ratio of the number of events at large and low $p_T$ at LHC, leads to similar sensitivities, if only the $H\to \gamma \gamma$ decay mode is used. But the sensitivities can now be improved by a factor 2 to 10, depending on the Higgs mass, if the Higgs decay modes to $WW^*$, $ZZ^*$, $WW$, $ZZ$ are also used.Comment: 23 pages and 7 figures, version to appear in Phys.ReV.D. e-mail: [email protected]

Charged Higgs- and R-Parity-Violating Slepton-Strahlung at Hadron Colliders

It is shown that the radiation of a charged Higgs boson off a third-generation quark (charged-Higgs-strahlung) provides an important channel for the discovery of the charged Higgs at hadron colliders. Equivalently, in supersymmetric models with explicit lepton-number (R-parity) violation, sleptons may also be produced in association with quarks (slepton-strahlung). Higgs- and slepton-strahlung production cross sections are given for both the Tevatron and the LHC. The LHC cross sections imply that heavy ${\cal{O}}$(TeV) charged Higgs bosons can be produced via charged-Higgs-strahlung and that strahlung production of charged sleptons is possible even for small R-parity violating couplings. The possible discovery of sleptons through this channel offers a surprising handle on models of neutrino masses.Comment: 23 pages, LaTex + RevTex, 11 figures (included). Title modified. (Published version.