Universality and mX cut effects in B→Xsl+l-

The most precise comparison between theory and experiment for the B -> X-s center dot(+)center dot(-) rate is in the low q(2) region, but the hadronic uncertainties associated with an experimentally required cut on m(X) potentially spoil the search for new physics in these decays. We show that a 10%-30% reduction of d Gamma(B -> X-s center dot(+)center dot(-))/dq(2) due to the m(X) cut can be accurately computed using the B -> X-s gamma shape function. The effect is universal for all short distance contributions in the limit m(X)(2)< m(B)(2), and this universality is spoiled neither by realistic values of the m(X) cut nor by alpha(s) corrections. Both the differential decay rate and forward-backward asymmetry with an m(X) cut are computed.