Violação de paridade em experimentos de espalhamentos de elétrons.

Abstract

Parity violation is a phenomenon present in particle decay and scattering processes, mediated by weak interactions and studied through the electroweak theory contained within the Standard Model. The parity violation measurement is made through the scattering of electrons with left and right helicity. This work presents the study of this asymmetry carried out by four generations of polarized electron scattering experiments on nuclear targets (SLAC E122, MIT – Bates, SAMPLE, HAPPEX, GO, A4 – Mainz, SLAC E158, Qweek, NuTev, MOLLER and P2) , linked to several particle accelerators (Stanford Linear Accelerator Center – SLAC, Bates Linear Acceleration Center – MIT, Thomas Jefferson National Accelerator Facility – TJNAF, Nuclear Instituty of Physics University Johannes Gutemberg). The objective of the work is to investigate the accuracy of the parity violation measurement and its relationship with the possible detection of a new Z’. Using a bibliographic and comparative approach, experimental data were analyzed from 1978 to 2016. This analysis was carried out in relation to previous research that addressed the possible detection of phenomena beyond the Standard Model, including the possibility of detecting the boson of caliber 𝑍 0 is mixed with Z’. The experimental equipment (Laser Cannon, Particle Beams, nuclear targets, as well as the detection system) were decisive for the accuracy of the measurements. The results of this research confirmed that the characterization of asymmetry is dependent on the choice of nuclear targets, but still, the development of new experiments is necessary to reduce statistical and systematic error rates to scales even smaller than current precision.