Drell-Yan and diphoton production at hadron colliders and low scale gravity model

Abstract

In the model of Arkani-Hamed, Dimopoulos, and Dvali where gravity is allowed to propagate in the extra dimensions of very large size, virtual graviton exchange between the standard model particles can give rise to signatures that can be tested in collider experiments. We study these effects in dilepton and diphoton production at hadron colliders. Specifically, we examine the double differential cross-section in the invariant mass and scattering angle, which is found to be useful in separating the gravity effects from the standard model. In this work, sensitivity obtained using the double differential cross-section is higher than that in previous studies based on single differential distributions. Assuming no excess of events over the standard model predictions, we obtain the following 95% confidence level lower limits on the effective Planck scale: 0.9 − 1.5 TeV in the Tevatron Run I, 1.3 − 2.5 TeV in Run IIa, 1.7 − 3.5 TeV in Run IIb, and 6.5 − 12.8 TeV at the LHC. The range of numbers corresponds to the number of extra dimensions n = 7 − 2.

Graviton collider effects in one and more large extra dimensions

“…In earlier works the reaches of the two lepton and the two photon channels have been found to be comparable [20,21]. The diphoton processes, however, suffers from several disadvantages: the total rate is only known at NLO [22], with an estimated error of about 20-30%.…”

Search for Large Extra Dimensions in Dielectron and Diphoton Production

“…These two variables completely define the 2 ! 2 scattering processes, and their properties provide improved separation between the SM contributions and the effects of virtual graviton exchange when compared to analyses of invariant-mass distributions alone [15].…”

“…The data are from the D0 experiment [14] at the Fermilab Tevatron, using proton-antiproton collisions at a center-of-mass energy of 1.8 TeV, and final states containing pairs of electrons or photons. We analyze the differential distribution [15] of dielectron or diphoton events in terms of their invariant mass and the scattering angle in their center-of-mass frame ͑u ‫ء‬ ͒. These two variables completely define the 2 !…”

“…[15] are introduced to optimize the sensitivity of the search. First, because the efficiency and resolution for high-energy electromagnetic (EM) objects at D0 are superior to those for muons, we use only the dielectron and diphoton channels, with the sensitivity to ED coming primarily from the diphoton events [15]. Second, to optimize the efficiency for diphoton and dielectron selection, we eliminate tracking requirements from electron and photon identification, thereby effectively combining them.…”

Search for Randall-Sundrum Gravitons in Dilepton and Diphoton Final States

“…These backgrounds were estimated using the leading or- der (LO) MC generator of Ref. [5], augmented with a parametric simulation of the DØ detector [6]. The simulation accounts for the calorimeter and tracker resolutions, primary vertex position, detector acceptance, and p T of the ℓℓ or γγ system.…”