Mechanisms of Auger-induced chemistry derived from wave packet dynamics

To understand how core ionization and subsequent Auger decay lead to bond breaking in large systems, we simulate the wave packet dynamics of electrons in the hydrogenated diamond nanoparticle C_(197)H_(112). We find that surface core ionizations cause emission of carbon fragments and protons through a direct Auger mechanism, whereas deeper core ionizations cause hydrides to be emitted from the surface via remote heating, consistent with results from photon-stimulated desorption experiments [Hoffman A, Laikhtman A, (2006) J Phys Condens Mater 18:S1517–S1546]. This demonstrates that it is feasible to study the chemistry of highly excited large-scale systems using simulation and analysis tools comparable in simplicity to those used for classical molecular dynamics

Production of W+W−W^+ W^- pairs via γ∗γ∗→W+W−\gamma^*\gamma^* \to W^+ W^- subprocess with photon transverse momenta

We discuss production of $W^+ W^-$ pairs in proton-proton collisions induced by two-photon fusion including, for a first time, transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of their arguments ($x$ and $Q^2$). In our approach we can get separate contributions of different $W$ helicities states. Several one- and two-dimensional differential distributions are shown and discussed. The present results are compared to the results of previous calculations within collinear factorization approach. Similar results are found except of some observables such as e.g. transverse momentum of the pair of $W^+$ and $W^-$. We find large contributions to the cross section from the region of large photon virtualities. We show decomposition of the total cross section as well as invariant mass distribution into polarisation states of both W bosons. The role of the longitudinal $F_L$ structure function is quantified. Its inclusion leads to a 4-5 % decrease of the cross section, almost independent of $M_{WW}$.Comment: 20 pages, 17 figures, 2 table

Electroweak Physics at LEP2

The measurements resulting from the analysis of the LEP2 data have brought more strong evidence in support of the standard electroweak model. In particular the LEP2 data has revealed (i) the first determination of the SU(2) gauge bosons self-couplings, (ii) the first direct measurements of the W decay-couplings, and (iii) the current best direct measurement of the W mass.Comment: 5 pages, 3 figures, contribution to the 2005 Lake Louise Winter Institut

Born-form approximation for e+ e- to W+ W- to 4 fermions(+gamma)

We review the results on representing the differential cross section for W-pair production, including W decay and hard-photon bremsstrahlung, in terms of a Born-form approximation of fairly simple analytic form.Comment: 16 pages with 3 figures,(eps files), Latex. Invited talk at the XXII International School of Theoretical Physics, Ustron '99, Poland, September 199

Strong WW scattering in unitary gauge

A method to embed models of strong $WW$ scattering in unitary gauge amplitudes is presented that eliminates the need for the effective $W$ approximation (EWA) in the computation of cross sections at high energy colliders.The cross sections obtained from the U-gauge amplitudes include the distributions of the final state fermions in $ff \rightarrow ffWW$, which cannot be obtained from the EWA. Since the U-gauge method preserves the interference of the signal and the gauge sector background amplitudes, which is neglected in the EWA, it is more accurate, especially if the latter is comparable to or bigger than the signal, as occurs for instance at small angles because of Coulomb singularities. The method is illustrated for on-shell $W^+W^+ \rightarrow W^+W^+$ scattering and for $qq \rightarrow qqW^+W^+$.Comment: 14 pages, Latex with 2 epsf-embedded postscript figure

Signals For Parity Violation in the Electroweak Symmetry Breaking Sector

We consider the possibility of observing a parity violating but $CP$ conserving interaction in the symmetry breaking sector of the electroweak theory. We find that the best probe for such an interaction is a forward-backward asymmetry in $W^+W^-$ production from polarized $e^-_R e^+_L$ collisions. An observable asymmetry would be strong evidence against a custodial $SU(2)$ symmetry. We also discuss the effects of such an interaction in future $e^- \gamma$ colliders as well as in rare decays of $K$ and $B$ mesons.Comment: Some sentences were added and others changed to clarify the discussion, 14 pages LaTe