Search For Dark Matter And Unparticles Produced In Association With A Z Boson In Proton Proton Collisions At Sqrt S

Search for Dark Matter and Unparticles Produced in Association with a Z Boson in Proton-proton Collisions at Sqrt(s)

A search for evidence of particle dark matter (DM) and unparticle production at the LHC has been performed using events containing two charged leptons, consistent with the decay of a Z boson, and large missing transverse momentum. This study is based on data collected with the CMS detector corresponding to an integrated luminosity of 19.7 inverse femtobarns of pp collisions at the LHC at a center-of-mass energy of 8 TeV. No significant excess of events is observed above the number expected from the standard model contributions. The results are interpreted in terms of 90% confidence level limits on the DM-nucleon scattering cross section, as a function of the DM particle mass, for both spin-dependent and spin-independent scenarios. Limits are set on the effective cutoff scale Lambda, and on the annihilation rate for DM particles, assuming that their branching fraction to quarks is 100%. Additionally, the most stringent 95% confidence level limits to date on the unparticle model parameters are obtained.

Search for Dark Matter and Unparticles in Events with a Z Boson and Missing Transverse Momentum in Proton-proton Collisions at Sqrt(s)

A search for dark matter and unparticle production at the LHC has been performed using events containing two charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum. This study is based on data collected with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 inverse femtobarns of proton-proton collisions at the LHC, at a center-of-mass energy of 13 TeV. No excess over the standard model expectation is observed. Compared to previous searches in this topology, which exclusively relied on effective field theories, the results are interpreted in terms of a simplified model of dark matter production for both vector and axial vector couplings between a mediator and dark matter particles. The first study of this class of models using CMS data at sqrt(s)=13 TeV is presented. Additionally, effective field theories of dark matter and unparticle production are used to interpret the data.

Search for Dark Matter and Unparticles Produced in Association with a Z Boson in Proton-proton Collisions at √s