Light Higgs production at the Compton Collider

We have studied the production of a light Higgs boson with a mass of 120 GeV in photon-photon collisions at a Compton collider. The event generator for the backgrounds to a Higgs signal due to bbbar and ccbar heavy quark pair production in polarized gamma-gamma collisions is based on a complete next-to-leading order (NLO) perturbative QCD calculation. For J_z=0 the large double-logarithmic corrections up to four loops are also included. It is shown that the two-photon width of the Higgs boson can be measured with high statistical accuracy of about 2 % for integrated gamma-gamma luminosity in the hard part of the spectrum of 40 fb**-1. As a result the total Higgs boson width can be calculated in a model independent way to an accuracy of about 14 %Comment: submitted to the proceedings of the International Workshop on Linear Colliders (LCWS99) at Sitges, Spain, 28 April - 5 May 199

Higgs Physics at a \gamma \gamma Collider

High precision measurements of electroweak observables at $e^\pm$ colliders indicate the existence of a light Higgs boson below the $W^\pm$ threshold. If such a fundamental scalar should be found in the near future it is important to fully investigate the electroweak symmetry braking sector of the Standard Model. This is particularly important for an intermediate mass Higgs as its existence might indicate physics beyond the Standard Model, for instance in form of its minimal supersymmetric extension (MSSM). In this work we present first results on the expected precision of the partial $\Gamma (H \longrightarrow \gamma \gamma)$ width at the $\gamma \gamma$ option of a future linear collider. This quantity is sensitive to new physics as heavy particles do not decouple in general and differences between the SM and MSSM predictions can differ by up to 10% even in the decoupling limit of large pseudoscalar Higgs masses. This regime is difficult and for some values of $\tan \beta$ impossible to cover at the LHC. We find that the well understood background process $\gamma \gamma \longrightarrow q \bar{q}$ allows for a ${\cal O} (2$ determination of $\Gamma (H \longrightarrow \gamma \gamma)$ using conservative collider parameters.Comment: Contribution to Photon 99 in Freiburg, Germany, and the international linear collider workshop in Sitges, Spai

Pair production of W bosons at the photon linear collider: a window to the electroweak symmetry breaking?

Recent progress in calculating O(alpha) electroweak corrections to W+W- pair production in photon-photon collisions is reviewed. The potential of the Photon Linear Collider to study anomalous W couplings is discussed.Comment: Talk given at 5th International conference on physics Beyond the Standard Model, Balholm, Norway, April 29 - May 4, 1997, 6 pages, 2 Postscript figures, uses epsf.st

Using Charge Asymmetries to Measure Single Top Quark Production at the LHC

Electroweak production of single top quarks is an as-yet-unverified prediction of the Standard model, potentially sensitive to new physics. Two of the single top quark productions channels have significant charge asymmetries at the LHC, while the much larger background from $t\bar{t}$ is nearly charge-symmetric. This can be used to reduce systematic uncertainties and make precision measurements of single top quark production.Comment: 4 pages, 1 figur