Engineering topics

Bergauer, Thomas

Publications and source records attributed to Bergauer, Thomas.

309 records · Page 18

DOE OSTI2011

Search for signatures of extra dimensions in the diphoton mass spectrum at the Large Hadron Collider

A search for signatures of extra dimensions in the diphoton invariant-mass spectrum has been performed with the CMS detector at the LHC. No excess of events above the standard model expectation is observed using a data sample collected in proton-proton collisions at {radical}s = 7 TeV corresponding to an integrated luminosity of 2.2 fb{sup -1}. In the context of the large-extra-dimensions model, lower limits are set on the effective Planck scale in the range of 2.3-3.8 TeV at the 95% confidence level. These limits are the most restrictive bounds on virtual-graviton exchange to date. The most restrictive lower limits to date are also set on the mass of the first graviton excitation in the Randall-Sundrum model in the range of 0.86-1.84 TeV, for values of the associated coupling parameter between 0.01 and 0.10.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Exclusive photon-photon production of muon pairs in proton-proton collisions at sqrt(s) = 7 TeV

A measurement of the exclusive two-photon production of muon pairs in proton-proton collisions at {radical}s = 7 TeV, pp {yields} p{mu}{sup +}{mu}{sup -}p, is reported using data corresponding to an integrated luminosity of 40 pb{sup -1}. For muon pairs with invariant mass greater than 11.5 GeV, transverse momentum p{sub T}({mu}) > 4 GeV and pseudorapidity |{eta}({mu})| < 2.1, a fit to the dimuon p{sub T}({mu}{sup +}{mu}{sup -}) distribution results in a measured cross section of {sigma}(p {yields} p{mu}{sup +}{mu}{sup -}) = 3.38{sub -0.55}{sup +0.58}(stat.) {+-} 0.16(syst.) {+-} 0.14(lumi.) pb, consistent with the theoretical prediction evaluated with the event generator LPAIR. The ratio to the predicted cross section is 0.83{sub -0.13}{sup +0.14}(stat.) {+-} 0.04(syst.) {+-} 0.03(lumi.). The characteristic distributions of the muon pairs produced via {gamma}{gamma} fusion, such as the muon acoplanarity, the muon pair invariant mass and transverse momentum agree with those from the theory.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Measurement of the t t-bar production cross section and the top quark mass in the dilepton channel in pp collisions at sqrt(s) =7 TeV

The t{bar t} production cross section and top quark mass are measured in proton-proton collisions at {radical}s = 7 TeV in a data sample corresponding to an integrated luminosity of 36 pb{sup -1} collected by the CMS experiment. The measurements are performed in events with two leptons (electrons or muons) in the final state. Results of the cross section measurement in events with and without b-quark identification are obtained and combined. The measured value is {sigma}{sub t{bar t}} = 168 {+-} 18 (stat.) {+-} 14 (syst.) {+-} 7 (lumi.) pb, consistent with predictions from the standard model. The top quark mass m{sub top} is reconstructed with two different methods, a full kinematic analysis and a matrix weighting technique. The combination yields a measurement of m{sub top} = 175.5 {+-} 4.6 (stat.) {+-} 4.6 (syst.) GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗