Search for Magnetic Monopoles in root s=7 TeV pp Collisions with the ATLAS Detector

This Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0 fb\u20131of pp collisions recorded at a center-of-mass energy of 1as = 7 TeV. No event is found in the signal region, leading to an upper limit on the production cross section at 95% confidence level of 1.6/\u3f5 fb for Dirac magnetic monopoles with the minimum unit magnetic charge and with mass between 200 GeVand 1500 GeV, where \u3f5 is the monopole reconstruction efficiency. The efficiency \u3f5 is high and uniform in the fiducial region given by pseudorapidity 23\u3b7 23 < 1.37 and transverse kinetic energy 600\u2013700 < Ekinsin\u3b8 < 1400 GeV. The minimum value of 700 GeV is for monopoles of mass 200 GeV, whereas the minimum value of 600 GeV is applicable for higher mass monopoles. Therefore, the upper limit on the production cross section at 95% confidence level is 2 fb in this fiducial region. Assuming the kinematic distributions from Drell-Yan pair production of spin-1/2 Dirac magnetic monopoles, the efficiency is in the range 1%\u201310%, leading to an upper limit on the cross section at 95% confidence level that varies from 145 fb to 16 fb for monopoles with mass between 200 GeV and 1200 GeV. This limit is weaker than the fiducial limit because most of these monopoles lie outside the fiducial region

Search for the Standard Model Higgs boson produced in association with a vector boson and decaying to a b-quark pair with the ATLAS detector

This Letter presents the results of a direct search with the ATLAS detector at the LHC for a Standard Model Higgs boson of mass 110 llbb, WH->lvbb, and ZH->vvbb, where l corresponds to an electron or a muon. No evidence for Higgs boson production is observed in a dataset of 7 TeV pp collisions corresponding to 4.7/fb of integrated luminosity collected by ATLAS in 2011. Exclusion limits on Higgs boson production, at the 95% confidence level, of 2.5 to 5.5 times the Standard Model cross section are obtained in the mass range 110 - 130 GeV. The expected exclusion limits range between 2.5 and 4.9 for the same mass interval