Leptoquark production at next-to-leading order

• Main Author: Hammett, Jason
• Other Authors: Ross, Douglas
• Published: University of Southampton 2014
• Subjects: 539.7; QC Physics
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.655332

In this thesis we study the effective leptoquark model of Buchm�uller, R�uckl and Wyler, focusing on a particular type of scalar (R2) and vector (U1) leptoquark. The primary aim is to perform the calculations for leptoquark production at next-to-leading order (NLO) to establish the importance of the NLO contributions and in addition to this to determine how effective the narrow-width-approximation (NWA) is at NLO. For both the scalar and vector leptoquarks it is found that the NLO contributions are large, with the largest corrections occurring to the vector leptoquark calculations. For the scalar leptoquark it is found that the NWA provides a good approximation for determining the resonant peak, however the NWA is not as effective for the vector leptoquark - where large differences are observed at NLO. For both the scalar and vector leptoquarks it is found that there are large contributions away from the resonant peak, which are missing from the NWA results, and these make a significant difference to the total cross-section.