Higgs Self-Coupling in gamma-gamma Collisions

To establish the Higgs mechanism experimentally, one has to determine the Higgs self-interaction potential responsible for the electroweak symmetry breaking. This requires a measurement of the trilinear and quadrilinear self-couplings of the Higgs particle, as predicted by the Standard Model (SM). We propose to measure the trilinear Higgs self-coupling in gamma-gamma collisions just above the kinematic threshold E_thr = 2M_H, where M_H is the Higgs mass. Our calculation reveals that the sensitivity of the cross-section sigma(gamma gamma -> HH) to the Higgs self-coupling is maximal near the 2M_H threshold for M_H = 115-150 GeV, and is larger than the sensitivities of sigma(e+e- -> ZHH) and sigma(e+e- -> nu nu HH) to this coupling for 2E_e < 700 GeV. We envisage to (a) study gamma gamma -> H by constructing an X-band e-e- linac and a terawatt laser system in order to produce Compton-scattered gamma-ray beams for a 160-GeV photon collider (2E_e = 200 GeV); (b) add a positron source and repeat all measurements done at LEP and SLC with much better precision; and (c) subsequently install 70-MeV/m rf cavities in order to study e+e- -> H+Z, e+e- -> tt and gamma gamma -> H+H at 2E_e = 350 GeV. The total length of the linac would be about 7 km.Comment: 14 pages, 5 figures, LaTeX. Submitted to Phys. Rev.

Modeling Deep Inelastic Cross Sections in the Few GeV Region

We present preliminary results on simple modifications and corrections to GRV94 leading order parton distribution functions such that they can be used to model electron,muon and neutrino deep-inelastic scattering cross sections at low energies.Comment: 6 pages, 6 figures. Presented by Arie Bodek at NuInt01, the First International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region, Dec. 2001, KEK, Tsukuba, Japan. To be published in Nucl. Physics B. Proceedings Supplement, Fall 200

Pair Production of Two-Higgs-Doublet_Model Light Higgs Bosons in γγ\gamma \gamma Collisions

We study the production of a pair of light, neutral, CP-even Higgs bosons in photon--photon collisions within the general Two Higgs Doublet Model (THDM). This is a process for which the lowest order contribution in both, the Standard Model and the THDM, appears at one loop. We find that the cross section for this process can be much larger in the THDM than in the Standard Model and the number of events expected at the Photon Collider will allow a determination of some of the parameters in the scalar potential.Comment: 10 pages, 4 figure

Improved low Q2 model for neutrino and electron nucleon cross sections in few GeV region

We present an improved model on neutrino- and electron-nucleon scattering cross sections using effective leading order PDFs with a new scaling variable xi_w. Non-perturbative QCD effects at low Q^2 are separately treated for u and d valence quarks, and sea quarks. The improved model uses all inelastic charged lepton F_2 data (SLAC/BCDMS/NMC/HERA), and photoproduction data on proton and deuterium. In this way, we obtain an improved model which describes all inelastic scattering charged lepton data, JLAB resonance data, and neutrino data. This improved model is expected to be better for neutrino oscillation experiments at few GeV region.Comment: Prepared for International Workshop on Neutrino-Nucleus Interactions in the Few GeV Regions (NuInt04), Gran Sasso Lab., Italy, March, 2004, 6 pages, 10 figure

Introduction to the Photon Collider

The purpose of this Introduction, presented at PHOTON2007, is to provide an overview of the basic principles, possible parameters, some technical aspects and the physics program of the photon collider and discuss its status within the ILC project.Comment: Talk at Photon2007, Paris, July 9-13, 2007, to be published in Nucl. Phys. B, 17 pp, Latex, 10 .eps figure

Charmonium production at neutrino factories

At existing and planned neutrino factories (high energy and high intensity neutrino beam facilities) precision studies of QCD in neutrino-nucleon interactions are a realistic opportunity. We investigate charmonium production in fixed target neutrino experiments. We find that $J/\psi$ production in neutrino-nucleon collision is dominated by the color octet $^3S_1$ NRQCD matrix element in a neutral current process, which is not accessible in photo or leptoproduction. Neutrino experiments at a future Muon Collider will acquire sufficient event rate to accurately measure color octet matrix element contributions. The currently running high energy neutrino experiments, NOMAD and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in the figures, otherwise unchange