Center-Edge Asymmetry at Hadron Colliders

We investigate the possibility of using the center-edge asymmetry to distinguish graviton exchange from other new physics effects at hadron colliders. Specifically, we study lepton-pair production within the ADD and RS scenarios. At the Tevatron, the graviton-Z interference is the most important contribution to the center-edge asymmetry, whereas at the LHC, the dominant contribution comes from gluon fusion via graviton exchange, which has no analogue at e^+ e^- colliders. We find that spin-2 and spin-1 exchange can be distinguished up to an ADD cut-off scale, M_H, of about 5 TeV, at the 95% CL. In the RS scenario, spin-2 resonances can be identified in most of the favored parameter space.Comment: 23 pages, including figure

Graviton-induced Bremsstrahlung at e^+e^- colliders

We consider graviton-induced Bremsstrahlung at future e^+e^- colliders in both the ADD and RS models, with emphasis on the photon perpendicular momentum and angular distribution. The photon spectrum is shown to be harder than in the Standard Model, and there is an enhancement for photons making large angles with respect to the beam. In the ADD scenario, the excess at large photon perpendicular momenta should be measurable for values of the cut-off up to about twice times the c.m. energy. In the RS scenario, radiative return to graviton resonances below the c.m. energy can lead to large enhancements of the cross section.Comment: 23 pages, including figure

Two Graviton Production at e+e−e^+e^- and Hadron Hadron Colliders in the Randall-Sundrum Model

We compute the pair production cross section of two Kaluza Klein modes in the Randall-Sundrum model at $e^+e^-$ and hadron hadron colliders. These processes are interesting because they get dominant contribution from the graviton interaction at next to leading order. Hence they provide a nontrivial test of the low scale gravity models. All the Feynman rules at next to leading order are also presented. These rules may be useful for many phenomenological applications including the computation of higher order loop corrections.Comment: 24 pages, 11 figures, some typos correcte

Large extra dimension effects in Higgs boson production at linear colliders and Higgs factories

In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza-Klein graviton and graviscalar interference with Higgs boson production amplitudes are computed at linear colliders and Higgs factories. The interference of the almost-continuous spectrum of the KK gravitons with the standard model resonant amplitude is finite and predictable in terms of the fundamental D-dimensional Plank scale M_D and the number of extra dimensions \delta. We find that, for M_D ~ 1 TeV and \delta=2, effects of the order of a few percent could be detected for heavy Higgs bosons (m_H>500 GeV) in Higgs production both via WW fusion in e^+e^- colliders and at \mu^+\mu^- Higgs-boson factories.Comment: 16 pages, 2 figures ; a few comments and references added ; version to appear in JHE

Graviton-induced Bremsstrahlung

We discuss photon Bremsstrahlung induced by virtual graviton exchange in proton-proton interactions at hadronic colliders, resulting from the exchange of Kaluza-Klein excitations of the graviton. The relevant subprocesses, gg to G to e^+e^-gamma and q barq to e^+e^-gamma are discussed in both the ADD and the RS scenarios. Although two-body final states (or real graviton emission) would presumably be the main discovery channels, a search for three-body final states could be worthwhile since such events have characteristic features that could provide additional confirmation. In particular, the k_perp-distribution of the photon is in both scenarios harder than that of the Standard-model background.Comment: 24 pages, including figures. v2: Including initial-state Bremsstrahlung and photon k_perp spectra. Version to appear in PR