Exotic leptoquarks from superstring derived models

Abstract

The H1 and ZEUS collaborations have recently reported a significant excess of events at high $Q^2$ in positron-proton collisions. While there exists insufficient data to conclusively determine the origin of this excess, one possibility is that it is due to a new leptoquark at mass scale around 200 GeV. We examine the type of leptoquark states that exist in superstring derived standard-like models, and show that, while these models may contain the standard leptoquark states which exist in Grand Unified Theories, they also generically contain new and exotic leptoquark states with fractional lepton number, $\pm 1/2$. In contrast to the traditional GUT-type leptoquark states, the couplings of the exotic leptoquarks to the Standard Model states are generated after the breaking of $U(1{)}_{B-L}$. This important feature of the exotic leptoquark states may result in local discrete symmetries which forbid some of the undesired leptoquark couplings. We examine these couplings in several models and study the phenomenological implications. The flavor symmetries of the superstring models are found to naturally suppress leptoquark flavor changing processes.

28 pages. Standard Latex. Final version to appear in Nuclear Physics B. Minor changes. References added

References in corpus (7)

• Comparison of ZEUS Data with Standard Model Predictions for e^+ p -> e^+ X Scattering at High x and Q^2
• Observation of Events at Very High Q^2 in ep Collisions at HERA
• Leptoquark/Squark Interpretation of HERA Events: Virtual Effects in e+e- Annihilation to Hadrons
• Comments on the high-$Q^2$ HERA anomaly
• QCD aspects of leptoquark production at HERA
• QCD Corrections and the Leptoquark Interpretation of the HERA High Q^2 Events
• Are the H1 and ZEUS "High Q^2 Anomalies" Compatible with Each Other?

Cited by in corpus (3)

• Physics of leptoquarks in precision experiments and at particle colliders
• Model independent constraints on leptoquarks from MU and TAU lepton rare processes
• Don't Stop Thinking About Leptoquarks: Constructing New Models