In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza-Klein gravitons on the imaginary part of the amplitude of the process e(+)e(-) --> f (f) over bar are analyzed at the Z pole. Notably, 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 Planck scale M-D. We find that, while the virtual-graviton effect on total cross sections vanishes at tree-level, both angular and polarization asymmetries are modified by terms whose relative effect is at most of order 10(-4) for M-D > 1 TeV. Possible shifts in M-Z, due to the changes in Breit-Wigner line shape are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
Virtual graviton exchanges at the Z pole in large extra dimensions
GABRIELLI, Emidio;
2003-01-01
Abstract
In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza-Klein gravitons on the imaginary part of the amplitude of the process e(+)e(-) --> f (f) over bar are analyzed at the Z pole. Notably, 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 Planck scale M-D. We find that, while the virtual-graviton effect on total cross sections vanishes at tree-level, both angular and polarization asymmetries are modified by terms whose relative effect is at most of order 10(-4) for M-D > 1 TeV. Possible shifts in M-Z, due to the changes in Breit-Wigner line shape are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.Pubblicazioni consigliate
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