IIHE topical seminar: Associated production of a Z boson and b jets in proton-proton collisions at 8 TeV in CMS

by Dr Vieri Candelise (University of Trieste)

Tuesday 17 Nov 2015, 14:30 → 15:30 Europe/Brussels

Jean Sacton Seminar room (1G003) (IIHE, VUB)

abstract: The associated production of a Z boson and b jets in hadronic collisions is a large background source for both the Higgs boson production and for many searches of physics beyond the standard model (SM). Its description constitutes an important benchmark for perturbative quantum chromodynamics (pQCD) predictions involving b quarks. Differential cross sections as a function of kinematic observables characterizing the Z + b jets topologies are sensitive to the contribution for both the hard scattering process and the soft QCD radiation associated with it, as well as to the parton distribution functions (PDFs). Within the Standard Model, the Z+b final state is the dominant background for studies of Higgs boson production in the HZ mode, and many physics scenarios beyond the Standard Model predict final states with b quarks and Z bosons: new generations of heavy quarks decaying into Z+b, supersymmetric Higgs bosons produced in association with b quarks, and extended Standard Model scenarios with additional SU(2) doublets with enhanced Zbb coupling. The Z + (at least one) b jet and Z + (at least two) b jets differential cross sections, measured as a function of several kinematic observables of the event at 8 TeV with the CMS detector will be presented. Experimental results will be compared to several pQCD predictions at LO and NLO and with different b quark definition in the calculations.