QCD Corrections to SUSY Higgs Production: The Role of Squark Loops

We calculate the two-loop QCD corrections to the production of the neutral supersymmetric Higgs bosons via the gluon fusion mechanism at hadron colliders, including the contributions of squark loops. To a good approximation, these additional contributions lead to the same QCD corrections as in the case where only top and bottom quark loops are taken into account. The QCD corrections are large and increase the Higgs production cross sections significantly.Comment: 5 pages, latex, 2 figure

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

Top quark associated production of topcolor pions at hadron colliders

We investigate the associated production of a neutral physical pion with top quarks in the context of topcolor assisted technicolor. We find that single-top associated production does not yield viable rates at either the Tevatron or LHC. tt-associated production at the Tevatron is suppressed relative to Standard Model ttH, but at the LHC is strongly enhanced and would allow for easy observation of the main decay channels to bottom quarks, and possible observation of the decay to gluons.Comment: 13 pages, 4 figures, submitted to PR

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

Detecting a light Higgs boson at the Fermilab Tevatron through enhanced decays to photon pairs

We analyze the prospects of the Tevatron for finding a Higgs boson in the two photon decay mode. We conclude that the Standard Model (SM) Higgs boson will likely not be discovered in this mode. However, we motivate several theories beyond the SM, including the MSSM, that predict a Higgs boson with enhanced branching fractions into photons, and calculate the luminosity needed to discover a general Higgs boson at the Tevatron by a two-photon invariant mass peak at large transverse momentum. We find that a high luminosity Tevatron will play a significant role in discovering or constraining these theories.Comment: 20 pages, latex, 5 figure

R-parity violation and uses of the rare decay sneutrino-->gamma+gamma in hadron and photon colliders

We consider implications of the loop process sneutrino -> gamma gamma in the MSSM with R-parity violation for future experiments, where the sneutrino is produced as the only supersymmetric particle. We present a scenario for the R-parity violating couplings, where this clean decay, although rare with Br(sneutrino -> gamma gamma) ~ 10^{-6}, may be useful for sneutrino detection over a range of sneutrino masses at the LHC. Furthermore, the new sneutrino-gamma-gamma effective coupling may induce detectable sneutrino resonant production in gamma gamma collisions, over a considerably wide mass range. We compare sneutrino -> gamma gamma, gg throughout the paper with the analogous yet quantitatively very different, Higgs -> gamma gamma, gg decays and comment on the loop processes sneutrino -> WW, ZZ.Comment: 19 pages using REVTEX, 3 figures embadded in the text using epsfi

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]

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

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