Leptoquark
Leptoquarks (X and Y bosons ) are hypothetical elementary particles that couple to quarks and leptons at the same time. You are postulated in a number of models beyond the Standard Model of particle physics, such as in GUT models such as the Georgi - Glashow model, but so far could not be detected experimentally.
If leptoquarks exist, their exchange would allow the conversion of leptons into quarks and vice versa, and so explain the amount parity will the charge of the proton and electron. Their existence could also explain why there are as many quarks as leptons, and many other similarities of the quark and Leptonsektors.
Properties
The twelve leptoquarks were first introduced by Jogesh Pati and Abdus Salam in a SU ( 4 ) model, in which the lepton number is treated as a fourth color. You have integer spin (0 or 1) and carry electric charge and color:
Strong barriers to their coupling constant products - especially in leptoquarks that couple to left - and right-handed quarks - can be derived from leptonic Mesonenzerfällen ( the Pionenzerfall example ).
The Leptoquark Lagrangian contains terms that have the same form as in the supersymmetric Lagrangian, further, pseudoscalar interactions. By excluding these pseudoscalar interactions, the corresponding bounds on R- parity-violating supersymmetric interactions can be obtained from the bounds on Leptoquark interactions.
Classification
The classification of Buchmüller, Rückl and Wyler (BRW ) classification shares leptoquarks after the spin (0 or 1), the Fermionenzahl ( 0 or 2), the weak isospin and the coupling to the left - or right-handed fermions one.
Decay modes
An X boson decay mode would have the following:
The two decay products each have opposite chirality.
A Y- boson decay mode would have the following:
The first decay product of each left-handed and right-handed would be the second.
Here u denotes the up- quark, d the down quark, e is the positron ( anti-electron ) and νe the electron antineutrino. Similar decomposition products are available for the other particle generations.
In these reactions, neither the lepton number L nor the baryon number B are obtained (which allows the proton decay ), but the difference B - L.
Different decay rates of the X- boson and its antiparticle (similar to the K -meson ) the baryogenesis could explain at the beginning of our universe. It is namely that leptoquarks have existed only in a very short period, at the end of the GUT era shortly after the Big Bang. Then they were divided into quarks and leptons, and formed, in accordance with the theories, the asymmetry between matter and antimatter from.