1,721,087 research outputs found
Matrix elements and shower matching.
No full textIt is very important to design a strategy to take advantage of the
strength (and avoid the drawbacks) of both fixed order calculations and of Parton Shower-like evolution with subsequent hadronization of the partonic event. Hereweshall briefly review two such merging approaches: the CKKW
scheme and the MLMschem
Four-fermion productions at a γγ collider
No full textUsing the recently proposed ALPHA algorithm (and the resulting code) I compute the rate (at tree level) for the process . The bulk of the contribution is due to W pair production and decay. However a non negligible () contribution comes from other channels, mainly the production and decay of a W and a collinear charged fermion. Requiring that the reconstructed invariant mass lies in the intervals GeV and GeV one obtains a rate which is lower, by 25 \% and 4 \% respectively, than the rate obtained in the approximation, thus demonstrating the relevance of the finite W width
General properties of neutrino spin precession in magnetic field and their possible implication for solar neutrinos
No full textWe consider the problem of the spin (or spin-flavour) precession of the solar electron neutrinos veL, possessing a nonzero magnetic moment (or transition moment of magnetic dipole type) μν, in the magnetic field B of the sun, including the case when B twists continuously along the neutrino path. A lower bound on the product of μv and the absolute value of the transverse (with respect to the neutrino momentum) component of B, needed to induce a veL-->vR transition with a given probability, vR being a right-handed neutrino, is derived
A new approach to multi-jet calculations in hadron collisions
No full textThe ALPHA algorithm to evaluate the exact, tree-level matrix elements is reviewed in the context of multi-parton processes in QCD. The algorithm is suited for the authomatic calculation of tree-level scattering amplitudes and allows for straightforward inclusion of mass effects. It's CPU cost grows like Kn (K constant, n number of external particles) as opposed to the factorial growth of Feynman graphs. I also discuss the summation over colour configurations which is designed to allow the construction of parton-level event generators suitable to interfacing with a parton-shower evolution including the effects of colour-coherence. Explicit results for the total rates and differential distributions of processes with 8 final-state partons are given
Theoretical aspects of Higgs physics at the LHC
No full textThe strategies recently developed to study Higgs boson properties at the LHC are reviewed. It is shown how to obtain model-independent determinations of couplings to fermions and gauge bosons by exploiting different production and decay channels. We consider the case of Weak Boson Fusion Higgs production with
PACS: 14.80.Bn Standard-Model Higgs boson – 13.85.Hd Inelastic Scattering: many particle final stat
- …
