Multi-Boson Interactions at the LHC

This review covers results on the production of all possible electroweak boson pairs and 2-to-1 vector boson fusion at the CERN Large Hadron Collider (LHC) in proton-proton collisions at a center of mass energy of 7 and 8 TeV. The data were taken between 2010 and 2012. Limits on anomalous triple gauge couplings (aTGCs) then follow. In addition, data on electroweak triple gauge boson production and 2-to-2 vector boson scattering yield limits on anomalous quartic gauge boson couplings (aQGCs). The LHC hosts two general purpose experiments, ATLAS and CMS, which have both reported limits on aTGCs and aQGCs which are herein summarized. The interpretation of these limits in terms of an effective field theory is reviewed, and recommendations are made for testing other types of new physics using multi-gauge boson production.Comment: 53 pages, 48 figures, 4 table

Review of Top Quark Properties Measurements at the Tevatron

This review summarises the top quark physics program pursued at Fermilab’s Tevatron proton-antiproton collider, operating at a centre of mass energy of 1.96 TeV, and its two collider detectors CDF and D0. More than a decade after the discovery of the top quark at the Tevatron, it remains the only place to produce top quarks and study them directly until the Large Hadron Collider at CERN starts operation. The Tevatron’s increased luminosity and centre of mass energy offer the possibility to scrutinise the properties of the heaviest fundamental particle known to date by performing new measurements that were not feasible before, like the first evidence for electroweak production of top quarks and the resulting direct constraints on the involved couplings. In addition, the precision of prior measurements has been improved to an unprecedented level, illustrated for example by th

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurement of the J/psi production cross section in 920 GeV/c fixed-target proton-nucleus interactions

The mid-rapidity ( dσpN/dy at y=0 ) and total ( σpN ) production cross sections of Jψ mesons are measured in proton–nucleus interactions. Data collected by the HERA-B experiment in interactions of 920 GeV/c protons with carbon, titanium and tungsten targets are used for this analysis. The Jψ mesons are reconstructed by their decay into lepton pairs. The total production cross section obtained is σpNJ/ψ=663±74±46 nb/nucleon . In addition, our result is compared with previous measurements