QCD CORRECTIONS AND THE LEPTOQUARK INTERPRETATION OF THE HERA HIGH-Q(2) EVENTS

The excess of high-Q(2) events found by HI and ZEUS at HERA in e(+)p d eep-inelastic scattering above the Standard Model prediction motivates us to calculate the NLO QCD corrections to the HERA scalar leptoquark (or squark) production cross sections. We find that the corrections a re significant, of order 50% in the mass range of interest. We also ca lculate the leptoquark average transverse momentum squared and find it to be rather small. Various leptoquark production cross sections at t he Tevatron p (p) over bar collider are also considered. We investigat e in detail the leptoquark interpretation of the HERA data. First we a ssume a minimal leptoquark model with a single diagonal Yukawa couplin g to first family lepton and quark mass eigenstates only. In this case constraints from atomic parity violating experiments allow only isodo ublet scalar leptoquark production at HERA. This interpretation can be confirmed or ruled out in the near future by high luminosity data at the Tevatron. The Tevatron data already appear to rule out the vector leptoquark interpretation of the HERA data. We also consider a more ge neral model which allows for all possible left-handed, right-handed, f lavour and lepton number changing couplings. The allowed values of the Yukawa couplings of this general model offer several different interp retations of the data which are radically different from the minimal m odel solutions. However these somewhat nd hoc tuned solutions can easi ly be tested by future HERA experiments.