Pair production of charged Higgs scalars from electroweak gauge boson fusion

We compute the contribution to charged Higgs boson pair production at the Large Hadron Collider (LHC) due to the scattering of two electroweak (EW) gauge bosons, these being in turn generated via bremsstrahlung off incoming quarks: q q --> q q V^*V^* --> q q H^+H^- (V=gamma,Z,W^{+/-}). We verify that the production cross section of this mode is tan beta independent and show that it is smaller than that of H^+H^- production via q q-initiated processes but generally larger than that of the loop-induced channel gg --> H^+H^-. Pair production of charged Higgs bosons is crucial in order to test EW symmetry breaking scenarios beyond the Standard Model (SM). We show that the detection of these kind of processes at the standard LHC is however problematic, because of their poor production rates and the large backgrounds.Comment: 22 pages, latex, 8 figures (largely revised version to appear in JPG

Separation of a single photon and products of the π0,η,Ks0\pi^0,\eta, K^0_s meson neutral decay channels in the CMS electromagnetic calorimeter using neural network

The artificial neural network approach is used for separation of signals from a single photon $\gamma$ and products of the $\pi^0,\eta, K^0_s$ meson neutral decay channels on the basis of the data from the CMS electromagnetic calorimeter alone. Rejection values for the three types of mesons as a function of single photon selection efficiencies are obtained for two Barrel and one Endcap pseudorapidity regions and initial \Et of 20, 40, 60 and 100 GeV.Comment: 16 pages, uses cernrep.cls style fil

The Macrame 1024 node switching network

We report on the construction of a large network testbed using IEEE 1355 DS-link technology. One thousand nodes are interconnected by a switching fabric based on the STC104 packet switch. The system has been designed and constructed in a modular way in order to allow a variety of different network topologies to be investigated. Network throughput and latency have been studied for different network topologies under various traffic conditions

Top anti-top pair production via b quark initiated processes at the Large Hadron Collider

We study $bt\bar t$ production via subprocesses initiated by $b$-quarks at the Large Hadron Collider. Both QCD and electroweak interactions are included in the elementary scattering amplitudes for $bg\to b t\bar t$. Since the additional jet in the final state (arising from the bottom quark) is in most cases at very low transverse momentum and very high pseudorapidity, it tends to escape detection. Therefore, such a process can act as a background to double-top as well as to single-top channels exploited in top quark phenomenology at present and future hadron colliders. Furthermore, if the additional $b$-jet can be tagged then $bt\bar t$ samples can be exploited in constraining possible effects of New Physics. The relevance of this reaction in such contexts is discussed and various total and differential rates of phenomenological interest are givenComment: 29 pages, latex, epsfig, 6 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/moretti/cavendish_9703 and at http://www.hep.phy.cam.ac.uk/theory/papers