Search for Randall-Sundrum gravitons in the diphoton channel at CDF

Abstract

We report on a search for new particles in the diphoton channel using a data sample of pp collisions at √ s = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 5.4 fb −1 . The diphoton invariant mass spectrum of the data agrees well with the standard model expectation. We set upper limits on the production cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits on the graviton mass of 459 GeV/c 2 and 963 GeV/c 2 , at the 95% confidence level, for coupling parameters (k/M P l ) of 0.01 and 0.1 respectively.

Polarized top pair production in extra dimension models via photon-photon fusion at the CERN LHC

“…We have calculated exclusion regions for the À m 1 for 0:0015 < < 0:15, 0:0015 < < 0:5, and for the LHC integrated luminosities. But our obtained limit does not exclude the latest Tevatron limits [45]. Therefore we do not show the exclusion region for the À m 1 .…”

Search for New Dielectron Resonances and Randall-Sundrum Gravitons at the Collider Detector at Fermilab

“…Figure 4 shows the exclusions in the k= " M Pl vs m 1 parameter space for the dielectron analysis, the diphoton analysis and their combination. For k= " M Pl ¼ 0:1, the inclusion of electrons improves the previous CDF RSgraviton limit [2] by $95 GeV=c 2 and surpasses the previous published [7] best limit by $40 GeV=c 2 . Table I summarizes the combined ee= RS-graviton lower-mass limits for different values of k= " M Pl .…”

“…The search for dielectron resonances is additionally motivated by the event excess at a dielectron mass M ee ¼ 240 GeV=c 2 reported by a CDF analysis [1] performed with an integrated luminosity of 2:5 fb À1 . Moreover, a recent CDF search [2] for Randall-Sundrum (RS) gravitons decaying to diphotons will benefit significantly from the addition of the dielectron decay channel. The RS model [3] G) that couple to SM particles and can be individually detected as resonances of pairs of jets, leptons, photons, or gauge bosons.…”

“…Given the considerable dijet background in a hadron-collider environment, and the low leptonic branching fraction of the weak bosons, the prompt dilepton and diphoton final states offer the greatest sensitivity. The inclusion of dielectrons in the diphoton RS search [2] results in a 50% increase in the rate of potentially produced signal. Here we present the cross section and mass limits for the dielectron channel alone and for the combined dielectron and diphoton channels.…”

“…eeÞ] upper limit as a function of the lightest RS-graviton mass m 1 along with five theoretical cross-section curves for k= " M Pl ¼ 0:01 to 0.1, a theoretically interesting range that would provide a solution for the hierarchy problem. The limits are set using a frequentist method that compares the background-only with the signal+background hypotheses, taking into account correlated background systematic uncertainties [2,18]. The intersection of the cross-section exclusion limit with the theoretical cross-section curves gives the 95% C.L.…”