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CERN

Developing a set of jet substructure observables to probe beyond-LL aspects of QCD showers

Student: 
Emma Kuwertz, CERN, four months from May 2014.
Date: 
May, 2014 to September, 2014
A significant number of measurements and searches at the Large Hadron Collider (LHC) include events with production of many hadrons, which are grouped into objects called jets. While some modern generators, including MadGraph, Sherpa, and Alpgen, are able to model the production of additional jets with a many-parton final state in the matrix element, all rely on the use of a parton shower to model the production of additional softer jets and the sub-structure of all jets in the event.

Developing a new model for colour reconnections in PYTHIA 8, based on SU(3) group weights

Student: 
Jesper Roy Christiansen
Date: 
February, 2014 to June, 2014

Colour reconnections have emerged as one of the main uncertain aspects of soft hadron-hadron collider physics, with significant implications for minimum-bias and underlying-event physics, as well as for precision measurements, most importantly the determination of the top quark mass in hadronic final states. We argue that a vital missing ingredient in current models is an understanding of the implications of QCD coherence on the process of hadronization, especially in the context of multiple parton interactions (MPI).

R-parity violating SUSY and generic BSM models in Pythia 8

Student: 
Nishita Desai
Date: 
August, 2010 to December, 2010

We describe the implementation of supersymmetric models in PYTHIA 8, including production and decay of superparticles and allowing for violation of flavour, CP, and R-parity. We also present a framework for importing generic new-physics matrix elements into PYTHIA 8, in a way suitable for use with automated tools. We emphasize that this possibility should not be viewed as the only way to implement new-physics models in PYTHIA 8, but merely as an additional possibility on top of the already existing ones.

Forward-backward and azimuthal correlations in pp collisions

Student: 
Kenneth Wraight
Date: 
January, 2010 to May, 2010

Measurements of inclusive observables, such as particle multiplicities and momentum spectra, have already delivered important information on soft-inclusive ("minimum-bias") physics at the Large Hadron Collider. In order to gain a more complete understanding, however, it is necessary to include also observables that probe the structure of the studied events. We argue that forward-backward (FB) correlations and event-shape observables may be particulary useful first steps in this respect.