The matrix elements of electroweak currents which occur in exclusive decays of heavy hadrons are evaluated in the nonperturbative light-cone Fock representration. In general, each semileptonic exclusive decay amplitude receives two contributions, a diagonal ∆n = 0 parton-number-conserving amplitude and a ∆n = −2 contribution in which a quark and an antiquark from the initial hadron Fock state a...

Jets observed in hadron-hadron scattering contain a contribution from the “underlying event” that is produced by spectator interactions taking place incoherently with the major parton-parton collision, due to the extended composite structure of the colliding hadrons. Using a recent measurement of the double parton interaction rate, we calculate that the underlying event may be 2–3 times stronge...

If the electroweak symmetry is broken by some unspecified strong dynamics, composite fermions may exist with definite transformation properties under SU(2)L×SU(2)R/SU(2)L+R and may play a role in giving masses by mixing to all the standard quarks and leptons. Assuming this to be the case, we analyze the role of Singlets, Doublets and Triplets in the ElectroWeak Precision Tests and in Flavour Ph...

Little Higgs models are an interesting alternative to explain electroweak symmetry breaking without fine-tuning. Supplemented with a discrete symmetry (T-parity) constraints from electroweak precision data are naturally evaded and also a viable dark matter candidate is obtained. T-parity implies the existence of new (mirror) fermions in addition to the heavy gauge bosons of the little Higgs mod...

If electroweak symmetry breaking arises via strongly-coupled physics, the observed suppression of flavour-changing processes suggests that fermion masses should arise via mixing of elementary fermions with composite fermions of the strong sector. The strong sector then carries colour charge, and may contain composite leptoquark states, arising either as TeV scale resonances, or even as light, p...

We present a mechanism to get S ≃ 0 or even negative, without bringing into play the SM fermion sector. This mechanism can be applied to a wide range of 5D models, including composite Higgs and Higgsless models. As a realization of the mechanism we introduce a simple model, although the effect on S does not rely on the underlying dynamics generating the background. Models that include this mech...

The current status of carlomat, a program for automatic computation of the lowest order cross sections of multiparticle reactions is described, the results of comparisons with other multipurpose Monte Carlo programs are shown and some new results on e + e − → b ¯ bb ¯ bu ¯ dd¯ u are presented. Many interesting aspects of the Standard Model (SM) and models beyond it can be studied through invest...

The exact matching condition is given for hadron matrix elements calculated in any two different schemes, in particular, in the lattice and dimensional regularization, (modified) minimal subtraction MS schemes. The result provides insight into and permits to go beyond Lepage and Mackenzie’s mean field theory of removing tadpole contributions in lattice operators. Typeset using REVTEX This work ...

Simulation of gamma and hadron showers in the energy range 100GeV- 25TeV has been carried out. For a big ideal Cherenkov light array, characteristics of lateral distribution of Cherenkov photon density have been studied. Results from this ideal detector are compared with those simulated for a real TUNKA- like array to investigate experimental potential of using existence of a hump in lateral di...