Search for magnetic monopoles in sqrt(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−1 of pp collisions recorded at a centerof-mass energy of √ s = 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/ fb for Dirac magnetic monopoles with the minimum unit magnetic charge and with mass between 200 GeV and 1500 GeV, where is the monopole reconstruction efficiency. The efficiency is high and uniform in the fiducial region given by pseudorapidity |η| < 1.37 and transverse kinetic energy 600–700 < Ekin sin θ < 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%–10%, 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. ar X iv :1 20 7. 64 11 v3 [ he pex ] 1 1 Ja n 20 13 Search for magnetic monopoles in √ s = 7 TeV pp collisions with the ATLAS detector The ATLAS Collaboration 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−1 of pp collisions recorded at a centerof-mass energy of √ s = 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/ fb for Dirac magnetic monopoles with the minimum unit magnetic charge and with mass between 200 GeV and 1500 GeV, where is the monopole reconstruction efficiency. The efficiency is high and uniform in the fiducial region given by pseudorapidity |η| < 1.37 and transverse kinetic energy 600–700 < E sin θ < 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%–10%, 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. PACS numbers: 14.80.Hv, 13.85.Rm, 29.20.db, 29.40.Cs Magnetic monopoles have long been the subject of dedicated search efforts for three main reasons: their introduction into the theory of electromagnetism would restore the symmetry between electricity and magnetism in Maxwell’s equations; their existence would explain the quantization of electric charge [1]; and they appear in many grand unified theories [2]. However, to date no experimental evidence of a magnetically charged object exists. Recent searches for magnetic monopoles from astrophysical sources [3–9] are complemented by searches at colliders [10–14]. This Letter describes a search for magnetic monopoles in proton–proton collisions recorded at a center-of-mass energy of √ s = 7 TeV using the ATLAS detector at the CERN Large Hadron Collider (LHC). The Dirac quantization condition [1], given in Gaussian units, leads to a prediction for the minimum unit magnetic charge g: