Sensitivity and backgrounds for the LUX dark matter search

The LUX 300~kg two-phase Xe detector aims to detect or exclude dark matter in the form of Weakly Interacting Massive Particles (WIMPs) with scalar cross section (per nucleon) as low as $7\times10^{-46}$~cm$^2$. This is equivalent to $\sim 0.5$~events/100~kg/month in a 100~kg fiducial volume. The LUX design is set to ensure $<1$ background event / 10~months live, which could potentially be characterized as a WIMP interaction. Based on above-ground calibrations and data from the XENON10 experiment, LUX expects to reject up to 99.9\% of the dominant electron-recoil background at detector threshold ($\sim4.5$~keVr), with 50\% acceptance for nuclear recoils. This level of electron recoil rejection power requires a gamma/beta background event rate of $<8\times10^{-4}$~events/keVee/kg/day at threshold $-$ a factor of $>150$ above the requisite nuclear recoil background rate. This talk will discuss projected backgrounds and sensitivity of the LUX experiment.