Bhabha Process Research Articles

We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated O~a! calculation of polarized Moiller scattering at c.m.s. energies large compared to 2 me . Both longitudinal and transverse polarizations are discussed. Possible applications to Moiller polarimetry at the SLD are thus illustrated. @S0556-2821~96!05713-X# ization utilizes the polarization dependence of the Moiller scattering cross section for polarized electrons in the SLC beam on a stationary polarized foil of known polarization- so-called Moiller polarimetry. While this method of measure- ment is not the primary method of measuring the SLC e 2 polarization, it is used @4# as an important cross check on the more accurate Compton polarimetry employed by the SLD Collaboration in their high precision ALR studies. Accord- ingly, radiative corrections to polarized Moiller scattering at the below 1% precision level are now of some interest. In this paper, we present the first results on the Yennis- Fraustchi-Suura ~YFS !@ 5 #exponentiated exact O~a! Monte Carlo approach @6# to these corrections in analogy with the results on the crossed Bhabha process presented in @7,8#, for example. Specifically, we extend the BHLUMI 1.xx Monte Carlo event generator in Ref. @7# to the crossed reaction of interest here. The extension involves introducing a new polarized matrix element into BHLUMI which is exact to O~a! for arbi- trarily polarized incoming e 2 beams. To this end, we follow the work of Ref. @9# for polarized Bhabha scattering and obtain the required exact O~a! matrix elements by crossing transformations on the virtual and soft corrections in this latter reference. For the corresponding O~a! hard brems- strahlung matrix element for Moiller scattering, we find it convenient to calculate it directly. These exact O~a! results are then combined with our standard YFS Monte Carlo methods as they pertain to Moiller scattering ~the respective YFS form factors are obtained via crossing from those al- ready in BHLUMI 1.xx! to yield the first ever realistic multiple photon Monte Carlo event generator for Moiller scattering with arbitrary initial beam polarizations. We call this new event generator BMOLLR. In what follows, we first review the relevant aspects of BHLUMI 1.xx insofar as our crossing transformations to the Moiller process are concerned. This is done in the next sec- tion. In Sec. III, we present the respective crossed virtual and soft corrections derived from Ref. @9#. In Sec. IV, we calcu- late the desired hard bremsstrahlung correction. In Sec. V, we combine our results to create BMOLLR and we present sample Monte Carlo data to illustrate the corresponding mul- tiple photon corrections. Comparisons with earlier analytic work in Refs. @10-12# as well as with recent SLD results @3# are also discussed in this section. Section VI contains some summary remarks.