Pat Kalyniak

Signatures of Doubly Charged Higgs Bosons in e gamma Collisions

We study the discovery potential for doubly charged Higgs bosons, Delta^--, in the process e- gamma -> e+ mu- mu- for centre of mass energies appropriate to high energy e^+e^- linear colliders and the CLIC proposal. For M_Delta < sqrt{s}_{e gamma} discovery is likely for even relatively small values of the Yukawa coupling to leptons. However, even far above threshold, evidence for the Delta can be seen due to contributions from virtual intermediate Deltas although, in this case, mu- mu- final states can only be produced in sufficient numbers for discovery for relatively large values of the Yukawa couplings.

Probing the contribution of gluons to the proton spin

Abstract We investigate the contribution to the proton spin from its gluonic content by studying the inelastic photoproduction of J/ψ off polarized protons with polarized photons. An expression for the asymmetry in the production of J/ψ from polarized protons is derived and results are presented in graphical form for selected energies and polarizations.

Precision measurements of W-boson properties in an e-γ collider

Abstract We study the possibility of making precision measurements of W-boson properties with an e-γ collider. We find that the measurements are comparable in sensitivity to W-pair production measurements to be made at the LEPII e + e − collider. In addition this process will be able to measure the W-photon anomalous magnetic moment, κ γ , independently of the W-Z 0 anomalous magnetic moment, κ Z 0 . This process is potentially a goldmine of W-boson physics and we strongly encourage that serious thought be given to the possibility of building such a collider.

Photon photon and electron photon colliders with energies below a TeV

We investigate the potential for detecting and studying Higgs bosons in {gamma}{gamma} and e{gamma} collisions at future linear colliders with energies below a TeV. Our study incorporates realistic {gamma}{gamma} spectra based on available laser technology, and NLC and CLIC acceleration techniques. Results include detector simulations. We study the cases of: (a) a SM-like Higgs boson based on a devoted low energy machine with {radical}(s{sub ee}) {le} 200 GeV; (b) the heavy MSSM Higgs bosons; and (c) charged Higgs bosons in e{gamma} collisions.

Phenomenology of neutral heavy leptons

We continue our previous work on the flavor-conserving leptonic decays of the Z boson with neutral heavy leptons (NHL`s) in the loops by considering box, vertex, and self-energy diagrams for the muon decay. By inclusion of these loops (they contribute to the input parameter M{sub W}), we can probe the full parameter space spanned by the so-called flavor-conserving mixing parameters ee{sub mix},{mu}{mu}{sub mix},{tau}{tau}{sub mix}. We show that only two diagrams from each class (box, vertex, and self-energy) are important; further, after renormalization only two box diagrams {open_quotes}survive{close_quotes} as dominant. We compare the results of our analysis with the existing work in this field and conclude that flavor-conserving decays have certain advantages over traditionally considered flavor-violating ones. {copyright} {ital 1997} {ital The American Physical Society}

Some constraints on neutral heavy leptons from flavor-conserving decays of the Z boson.

Small neutrino masses can arise in some grand unified models or superstring theories. We consider a model with an enhanced fermion sector containing Dirac neutral heavy leptons. The dependence on the mass and mixing parameters of these new fermions is investigated for several measurable quantities. We study the flavor-conserving leptonic decays of the Z boson and universality breaking in these decays. We also consider the W boson mass dependence on neutral heavy lepton parameters. PACS numbers(s): 14.60.-z, 12.15.Ff, 13.38.Dg

Photon- and Z-induced heavy charged lepton pair production at a hadron supercollider.

We investigate the pair production of charged heavy leptons via photon-induced processes at the proposed CERN Large Hadron Collider (LHC). Using effective photon and {ital Z} approximations, rates are given for {ital L}{sup +}{ital L}{sup {minus}} production due to {gamma}{gamma} fusion and {ital Z}{gamma} fusion for the cases of inelastic, elastic, and semielastic {ital pp} collisions. These are compared with the corresponding rates for production via the gluon fusion and Drell-Yan mechanisms. Various {gamma}{gamma} and {ital Z}{gamma} differential luminosities for {ital pp} collisions are also presented. {copyright} {ital 1996 The American Physical Society.}

Extracting W boson couplings from the e+e- production of four leptons.

We consider the processes

Symmetry-breaking scenarios of Wilson-loop broken E6

e^{+}e^{-}\rightarrow \ell^{+} \ell^{\prime -}\nu \bar{\nu}^{\prime}

DISCOVERY AND IDENTIFICATION OF W′ BOSONS AT e+e- COLLIDERS

, including all possible charged lepton combinations, with regard to measuring parameters characterizing the