The matrix element method (MEM) has been extensively used for the analysis of top-quark and W-boson physics at the Tevatron, but in general without dedicated treatment of initial state QCD radiation. ...At the LHC, the increased center of mass energy leads to a significant increase in the amount of QCD radiation, which makes it mandatory to carefully account for its effects. We here present several methods for inclusion of QCD radiation effects in the MEM, and apply them to mass determination in the presence of multiple invisible particles in the final state. We demonstrate significantly improved results compared to the standard treatment.
JHEP 0412:050,2004 We present a new method for matching the two twin-processes gb->H+/-t and
gg->H+/-tb in Monte Carlo event generators. The matching is done by defining a
double-counting term, which ...is used to generate events that are subtracted from
the sum of these two twin-processes. In this way we get a smooth transition
between the collinear region of phase space, which is best described by
gb->H+/-t, and the hard region, which requires the use of the gg->H+/-tb
process. The resulting differential distributions show large differences
compared to both the gb-> H+/-t and gg->H+/-tb processes illustrating the
necessity to use matching when tagging the accompanying b-jet.
Collider aspects of flavor physics at high Q LARI, T; PAPE, L; MOORTGAT, F ...
European physical journal. C, Particles and fields (Print),
2008, Letnik:
57, Številka:
1-2
Conference Proceeding
We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the ...merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5_aMC@NLO, capable of handling all these computations -- parton-level fixed order, shower-matched, merged -- in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV \(e^+e^-\) collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way.
We present a new method for matching the two twin-processes gb->H+/-t and gg->H+/-tb in Monte Carlo event generators. The matching is done by defining a double-counting term, which is used to ...generate events that are subtracted from the sum of these two twin-processes. In this way we get a smooth transition between the collinear region of phase space, which is best described by gb->H+/-t, and the hard region, which requires the use of the gg->H+/-tb process. The resulting differential distributions show large differences compared to both the gb-> H+/-t and gg->H+/-tb processes illustrating the necessity to use matching when tagging the accompanying b-jet.
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