Single-top production at future ep colliders

The production of top quarks in single mode at future ep colliders is studied, the attention being mainly focused to the case of the proposed LEPXLHC collider. We are motivated to reanalyse such a process following the discovery of the top quark at Fermilab. Thanks to the measurement of its mass one is now able to establish more accurately the relevance of single top production for itself and for many other processes to which it may act as a background. In addition, the recent improvement of our knowledge of the quark and gluon dynamics inside the proton now allows one to pin down the dependence of single top production on the partonic structure functions. Both the leptonic and hadronic decay channels of the top quark are studied and compared to the yield of the corresponding irreducible background in presence of b-taggingComment: 28 pages, latex, epsfig, 10 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/moretti/cavendish_9704 and at http://www.hep.phy.cam.ac.uk/theory/papers

Anomalous quartic WWgammagamma and WWZgamma couplings through WWZ production in gamma gamma colliders

We find 95% confidence level limits on the anomalous coupling parameters $a_0$, $a_c$ and $a_n$ with an integrated luminosity of $500fb^{-1}$ and $\sqrt s =0.5, 1$ and 1.5 TeV energies. We take into account incoming beam polarizations and also the final state polarizations of the gauge bosons in the cross-section calculations to improve the bounds. We show that polarization leads to a significant amount of improvement in the sensitivity limits.Comment: 16 pages, 6 figures, 3 table

Anomalous quartic couplings in W+W−γ W^+W^- \gamma production at e+e−e^+e^- colliders

We study the process $e^+e^- \rightarrow W^+W^- \gamma$ at high-energy $e^+ e^-$ colliders to investigate the effect of genuine quartic $W^+W^-\gamma\gamma$ and $W^+W^- Z\gamma$ anomalous couplings on the cross section. Deviations from the Standard Model predictions are quantified. We show how bounds on the anomalous couplings can be improved by choosing specific initial state helicity combinations. The dependence of the anomalous contributions on the collider energy is studied.Comment: 15 pages, DTP/94/1

Probing Anomalous Quartic Couplings in e-gamma and gamma-gamma Colliders

We analyze the potential of the e+e- Linear Colliders, operating in the e-gamma and gamma-gamma modes, to probe anomalous quartic vector--boson interactions through the multiple production of W's and Z's. We examine all $SU(2)_L \otimes U(1)_Y$ chiral operators of order p^4 that lead to new four--gauge--boson interactions but do not alter trilinear vertices. We show that the e-gamma and gamma-gamma modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10^{-2} at 90% CL. Moreover, the information gathered in the e-gamma mode can be used to reduced the ambiguities of the e+e- mode.Comment: Revtex, 18 pages, 6 figure

Tests of Anomalous Quartic Couplings at the NLC

We analyze the potential of the Next Linear $e^+e^-$ Collider to study anomalous quartic vector-boson interactions through the processes $e^+ e^- \to W^+W^-Z$ and $ZZZ$. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators of order $p^4$ that lead to four-gauge-boson interactions but do not induce anomalous trilinear vertices. In our analysis, we take into account the decay of the vector bosons to fermions and evaluate the efficiency in their reconstruction. We obtain the bounds that can be placed on the anomalous quartic interactions and we study the strategies to distinguish the possible couplings.Comment: 18 pages, ReVTeX, 3 figures, typos corrected and references adde

Anomalous Couplings in e^+ e^- --> W^+ W^- gamma at LEP2 and NLC

We present sensitivity limits on the coefficients of a dimension-6 effective Lagrangian that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the process $e^+ e^- \to W^+ W^- \gamma$ at LEP2 and NLC energies. In our calculations, we include all the new anomalous interactions, involving vector and Higgs bosons, and take into account the Standard Model irreducible background. We analyse the impact of these new interactions on the total cross section, including the effects of the initial electron and final W polarizations. We then focus on the operators that will not be constrained by the $e^+ e^- \to W^+ W^-$ process, obtaining limits based on the photon energy distribution.Comment: 20 pages + 12 figures, RevTex. Version to be published in Phys. Rev.

Plate-based diversity subset screening generation 2: An improved paradigm for high throughput screening of large compound files

High throughput screening (HTS) is an effective method for lead and probe discovery that is widely used in industry and academia to identify novel chemical matter and to initiate the drug discovery process. However, HTS can be time-consuming and costly and the use of subsets as an efficient alternative to screening these large collections has been investigated. Subsets may be selected on the basis of chemical diversity, molecular properties, biological activity diversity, or biological target focus. Previously we described a novel form of subset screening: plate-based diversity subset (PBDS) screening, in which the screening subset is constructed by plate selection (rather than individual compound cherry-picking), using algorithms that select for compound quality and chemical diversity on a plate basis. In this paper, we describe a second generation approach to the construction of an updated subset: PBDS2, using both plate and individual compound selection, that has an improved coverage of the chemical space of the screening file, whilst only selecting the same number of plates for screening. We describe the validation of PBDS2 and its successful use in hit and lead discovery. PBDS2 screening became the default mode of singleton (one compound per well) HTS for lead discovery in Pfizer