Sensitivity of wideband detectors to quintessential gravitons - art. no. 083511.

There is no reason why the energy spectra of the relic gravitons amplified by the pumping action of the background geometry should not increase at hig h frequencies. A typical example of this behavior is quintessential inflati on where the slopes of the energy spectra can be either blue or mildly viol et. In comparing the predictions of scenarios leading to blue and violet gr aviton spectra we face the problem of correctly deriving the sensitivities of the interferometric detectors. Indeed the expression of the signal-to-no ise ratio not only depends upon the noise power spectra of the detectors bu t also upon the spectral form of the signal and, therefore, one can reasona bly expect that models with different spectral behaviors will produce diffe rent signal-to-noise ratios. By assuming monotonic (blue) spectra of relic gravitons we will give general expressions for the signal-to-noise ratio in this class of models. As an example we study the case of quintessential gr avitons. The minimum achievable sensitivity to h(0)(2)Omega(GW) of differen t pairs of detectors is computed, and compared with theoretical expectation s. [S0556-2821(99)04718-9].