Use of transverse polarization to probe R-parity violating supersymmetry at ILC

Rohini M Godbole,Santosh Kumar Rai,Saurabh D Rindani

doi:10.1016/j.physletb.2009.06.053

Abstract

In supersymmetric theories with R-parity violation, squarks and sleptons can mediate Standard Model fermion–fermion scattering processes. These scalar exchanges in e+e− initiated reactions can give new signals at future linear colliders. We explore use of transverse beam polarization in the study of these signals in the process e+e−→bb¯. We highlight certain asymmetries, which can be constructed due to the existence of the transverse beam polarization, which offer discrimination from the Standard Model (SM) background and provide increased sensitivity to the R-parity violating couplings.

Highlights

In the Standard Model (SM), baryon and lepton number conservation is not guaranteed by local gauge invariance
The existence of all such terms can be forbidden by postulating a discrete symmetry [1], called R-parity, which implies a conserved quantum number Rp ≡ (−1)3B+L+S, where S stands for the spin of the particle
The very definition implies that all the SM particles have Rp = +1 while all the superpartners are odd under this symmetry

Summary

Introduction

In the Standard Model (SM), baryon and lepton number conservation is not guaranteed by local gauge invariance. This symmetry is an ad hoc measure and there does not exist an overriding theoretical motivation for imposing it, especially since a suppression of proton decay rate could as well be achieved by ensuring that one of B and L is conserved It has been argued [2] that this goal is better served by imposing a generalized baryon parity instead. Non-zero R-parity violating (RPV) couplings provide a means of generating the small neutrino masses, either at tree level or loop level, that the neutrino oscillation experiments seem to call for. The additional effects can depend quadratically on the RPV couplings rather than quartically This can make studies with transversely polarized beams more sensitive to R-parity violating couplings.

Transverse polarization at ILC

Sneutrino exchange in the s-channel

Squark exchange in the t-channel

Conclusions