List of previous students

Armando Bermudez Martinez
Nicola Orlando
Faten Hariri
Emma Kuwertz
Spyridon Argyropoulo
Sabrina Sacerdoti
Simone Amoroso
Jesper Roy Christiansen
Nathan Hartland
Christian Roehr
Benjamin Watt
Philip Ilten
Nishita Desai
Sercan Sen
Miroslav Myska
Sudha Ahuja
Holger Schulz
Avi Gershan
Aleksander Kusina
Magdalena Slawinska
Flavia Dias
Kenneth Wraight
Irais Bautista Guzman
Sparsh Navin
Paolo Francavilla
Riccardo Di Sipio
Seyi Latunde-Dada
Devdatta Majumder
Martijn Gosselink
Christopher Bignamini
Marek Schönherr
Michal Deak
Noam Hod
Florian Bechtel
Jonathan Ferland
Manuel Bähr
Alexander Flossdorf
Piergiulio Lenzi

Recently in CMS, we have measured the azimuthal separation between the two leading jets in multi-jet events when these are approximately back-to-back. We have also measured the more exclusive and complementary azimuthal separation between the leading jets when the presence of at least an extra much softer jet is required in the event. We have observed a tension between the data and the theory predictions from parton shower event generators as well as from improved predictions using higher order matrix elements.

Part of the effort within the three month MCnet project was to investigate, from the parton shower phenomenology point of you, the azimuthal separation between the two leading jets when these two are approximately back-to-back. We studied the role of the renormalization scale choice in the evolution of the parton shower. In addition, investigated the dependence on the handling of the soft gluon coherence in the shower by studying the pt ordered dipole shower from PYTHIA8, the matrix element corrected shower provided by the VINCIA generator, the angular order shower from HERWIG7, and also the DIRE shower which allows the use of next-to-leading splitting kernels in the evolution. Using PYTHIA8 we assessed the influence of the recoil strategy as well as the cut-off scale for the shower.

We investigated the possibility of measuring the azimuthal separation between the leading jets also in bins of rapidity. This could allowed the enhancement of specific QCD channels and the possible tagging of quark/gluon-like jets in back-to-back topologies. In addition we studied other observables that can be measured in a correlated way with the azimuthal angular separation between the leading jets. In this direction we investigated the jet structure in back-to-back topologies employing for this the so called jet angularities.

As part of the project we also investigated the disagreement observed by CMS for the minimum azimuthal separation in 4-jet events when merged LO samples with up to four partons in the final state are compared to data.

The investigations and subsequent results have been included as a very important complementary part of my PhD thesis.