Search for Large Extra Dimensions in the Dielectron and Diphoton Channels

The D0 Collaboration

Contact Persons: Greg Landsberg


We report preliminary results on search for large spatial extra dimensions in the dielectron and diphoton channels using ~130 pb-1 of data collected by the Dě Experiment at the Fermilab Tevatron in 2002-2003 (Run II). We set new limits on the fundamental Planck scale (MP) of 1.28 TeV (in the GRW convention), exceeding limits obtained with similar statistics in Run I. Combined with the published Run I result, this correspond to a lower limit of MP > 1.37 TeV, which is the most stringent limit on Large Extra Dimensions to date.

A detailed description is available as Dě note 4179 (restricted access; non-D0-speakers, please contact the D0 NP Convenors).




The diEM mass vs. cos(theta*) distribution. Top left: SM background from Drell-Yan and direct diphotons; top right: data; bottom left: ED signal plus the SM background for etaG=2.0; bottom right: instrumental background.




The diEM cos(theta*) distribution. Points with error bars are the data; light filled histogram represents the instrumental background from jets misidentified as EM objects; solid line shows the fit to the sume of the instrumental background and the SM predictions from Drell-Yan and direct diphoton backgrounds.




The diEM mass distribution. Points with error bars are the data; light filled histogram represents the instrumental background from jets misidentified as EM objects; solid line shows the fit to the sume of the instrumental background and the SM predictions from Drell-Yan and direct diphoton backgrounds. The dashed line shows the effect of the ED signal for etaG=0.6.




Expected 95% C.L. upper limit on the parameter etaG from an ensemble of MC experiments, together with the actual limits obtained in this analysis. Shaded histogram: Bayesian limit; open histogram: Likelihood limit. The arrows indicate Bayesian (solid) and Likelihood (dashed) limits derived from data.




Event Display of the highest-mass diEM candidate with the invariant mass of 406 GeV and cos(theta*) of 0.67. Note that the MEt for this event displayed in the lego plot does not reflect MEt corrections via CH1 cell subtraction.




Event Display of the highest-mass diEM candidate with the invariant mass of 406 GeV and cos(theta*) of 0.67.




Event Display of the second-highest-mass diEM candidate with the invariant mass of 394 GeV and cos(theta*) of 0.56.




Event Display of the second-highest-mass diEM candidate with the invariant mass of 394 GeV and cos(theta*) of 0.56.



Volker Buescher
Last modified: Wed Sep 17 01:39:50 CDT 2003