jlabounty / leptoquark

Analysis code used in leptoquark studies

leptoquark

The analysis macros in this repository are used in the following study.

In the Standard Model (SM) of particle physics, each conservation law has an associated symmetry, as stated by Emmy Noether’s eponymous theorem. However, within the Standard Model there exists no known symmetry which would lead to the conservation of Lepton Flavour (the number of each generation of lepton) which is commonly observed. Lepton Flavour Violations (LFV’s) have been shown to exist in solar neutrinos (neutrino oscillations), but no such violations have been observed experimentally with the massive leptons (e, μ, and τ ). Neutrino oscillations indicate that the SM should allow LFV decays such as μ → eγ. However, due to the minuscule masses of the neutrinos the rate of these violations is expected to be extraordinarily small (< 10−54) and thus out of the reach of any current or planned experiment[3]. However, certain extensions Beyond the Standard Model (BSM) pre- dict that violations of lepton flavor of the massive leptons could occur at much higher rates, which would be detectable by planned experiments. Thus, the study of LFV is attractive to those who wish to probe BSM physics.

A common model for LFV in many BSM theories is the leptoquark: a color triplet boson with both lepton and baryon quantum numbers. These leptoquarks would facilitate LFV events such as ep → τX, and are predicted to have cross sections many orders of magnitude greater than SM LFV events. Studies by the HERA collaboration have been conducted to identify leptoquark events, but none have yet been conclusively identified. This puts hard limits on the mass and coupling of any leptoquark. It has been shown in both [3] and [4] that the proposed Electron Ion Collider (EIC) upgrade to the facilities at Brookhaven National Laboratory[1] would provide sufficient integrated luminosity to improve on the production rates of the HERA experiment by up to 2 orders of magnitude. This will allow us to probe beyond the limits of the leptoquark mass set by HERA, and opens up the possibilities of new discoveries.

However, it is not enough to simply produce leptoquarks at a statistically significant rate, we must also be able to identify them. To that end, a study was undertaken here at Stony Brook which simulated leptoquark events using the LQGENEP generator and compared them to SM Deep Inelastic Scattering (DIS). There, it was shown that the profile of the jets produced from the τ decay were sufficiently unique that they could be distinguished from DIS events at the generator level. My goal is to repeat these studies at the detector level, in order to determine if this result still holds when the physical limits of the detectors are in place. If the results holds, then this study will provide a good case for the proposed EIC, as it will allow entirely new physics experiments to be undertaken.