Precision Higgs Physics at a Future Linear Collider

Assuming that a Higgs sector is responsible for electroweak symmetry breaking, we attempt to address two important questions: How much better precision are various measurements of Higgs boson properties at a future linear collider than at the LHC? What can a future linear collider do for Higgs physics that the LHC cannot?Comment: 10 pp, 4 eps fig, econf, invited talk at RADCOR 2000 (Carmel, CA, Sept 2000), includes additional comments and citations on multiple Higgs productio

Searching for H -> gamma gamma in weak boson fusion at the LHC

Weak boson fusion is a copious source of intermediate mass Higgs bosons at the LHC, with a rate sigma*B(H -> gamma gamma) of up to 9 fb. The additional very energetic forward jets in these events provide for a unique signature. A parton level analysis of the dominant backgrounds demonstrates that this channel allows the observation of H -> gamma gamma in a low background environment, with modest luminosity.Comment: 12 pages, 4 figures, submitted to Journal of High Energy Physic

Probing Neutral Gauge Boson Self-interactions in ZZ Production at Hadron Colliders

A detailed analysis of ZZ production at the upgraded Fermilab Tevatron and the CERN Large Hadron Collider is presented for general ZZZ and ZZ\gamma couplings. Deviations from the Standard Model gauge theory structure for each of these can be parameterized in terms of two form factors which are severely restricted by unitarity at high energy. Achievable limits on these couplings are shown to be a dramatic improvement over the limits currently obtained by e^+e^- experiments.Comment: 36 pages, 15 figures, revte

A new method for extracting the bottom quark Yukawa coupling at the CERN Large Hadron Collider

We propose a new method for measuring the H -> bb rate at the CERN LHC in a manner which would allow extraction of the b quark Yukawa coupling. Higgs boson production in purely electroweak WHjj events is calculated. The Standard Model signal rate including decays W -> l nu and H -> bb is 11 fb for M_H = 120 GeV. It is possible to suppress the principal backgrounds, Wbbjj and ttjj, to approximately the level of the signal. As the top quark Yukawa coupling does not appear in this process, it promises a reliable extraction of g_Hbb in the context of the Standard Model or some extensions, such as the MSSM.Comment: added background, updated/added references, additional comment

Probing the Higgs self-coupling at hadron colliders using rare decays

We investigate Higgs boson pair production at hadron colliders for Higgs boson masses m_H\leq 140 GeV and rare decay of one of the two Higgs bosons. While in the Standard Model the number of events is quite low at the LHC, a first, albeit not very precise, measurement of the Higgs self-coupling is possible in the gg -> HH -> b\bar{b}\gamma\gamma channel. A luminosity-upgraded LHC could improve this measurement considerably. A 200 TeV VLHC could make a measurement of the Higgs self-coupling competitive with a next-generation linear collider. In the MSSM we find a significant region with observable Higgs pair production in the small \tan\beta regime, where resonant production of two light Higgs bosons might be the only hint at the LHC of an MSSM Higgs sector.Comment: Revtex, 23 pages, 4 tables, 7 figure

TeV resonances in top physics at the LHC

We consider the possibility of studying novel particles at the TeV scale with enhanced couplings to the top quark via top quark pair production at the LHC and VLHC. In particular we discuss the case of neutral scalar and vector resonances associated with a strongly interacting electroweak symmetry breaking sector. We constrain the couplings of these resonances by imposing appropriate partial wave unitarity conditions and known low energy constraints. We evaluate the new physics signals via WW -> tt~ for various models without making approximation for the initial state W bosons, and optimize the acceptance cuts for the signal observation. We conclude that QCD backgrounds overwhelm the signals in both the LHC and a 200 TeV VLHC, making it impossible to study this type of physics in the tt~ channel at those machines.Comment: 15p, add. comments to clarify model, +2 ref., version to appear PR

H-->WW as the discovery mode for a light Higgs boson

The production cross section for a m_H=115 GeV, SM Higgs boson in weak boson fusion at the LHC is sizable. However, the branching fraction for H-->WW is expected to be relatively small. The signal, with its two forward jets, is sufficiently different from the main backgrounds that a signal to background ratio of better than 1:1 can nevertheless be obtained, with large enough rate to allow for a 5 sigma signal with 35 fb^{-1} of data. The H-->WW signal in weak boson fusion may thus prove to be the discovery mode for the Higgs boson at the LHC.Comment: 10 pages, 4 figures, uses revte