  One of the first orders of business for LHC experiments after beam turn-on
will be to calibrate the detectors using well understood Standard Model (SM)
processes such as W and Z production and ttbar production. These familiar SM
processes can be used to calibrate the electromagnetic and hadronic
calorimeters, and also to calibrate the associated missing transverse energy
signal. However, the presence of new physics may already affect the results
coming from these standard benchmark processes. We show that the presence of
relatively low mass supersymmetry (SUSY) particles may give rise to significant
deviations from SM predictions of Z+jets and W+jets events for jet multiplicity
$\ge 4$ or $\ge 5$, respectively. Furthermore, the presence of low mass SUSY
may cause non-standard deviations to appear in top quark invariant and
transverse mass distributions. Thus, effects that might be construed as
detector mal-performance could in fact be the presence of new physics. We
advocate several methods to check when new physics might be present within SM
calibration data.
