We consider the theory of spinor fields written in polar form, that is form which components are given terms a module times complex unitary phase respecting Lorentz covariance. In this formalism, spinors can be treated their most general mathematical without need to restrict them plane waves. As consequence, calculations scattering amplitudes performed by employing fermion propagator, and not o...

Using a dedicated data sample taken in 2018 on the $J/\psi$ peak, we perform detailed study of trigger efficiencies BESIII detector. The are determined from three representative physics processes, namely Bhabha-scattering, dimuon production and generic hadronic events with charged particles. combined efficiency all active triggers approaches $100\%$ most cases uncertainties small enough as not ...

Neutrinos are very elusive particles. Having only weak (and gravitational) interactions they are extremely difficult to detect, but their study has been always extremely rewarding, both for physics and (more recently) astrophysics. In the last several years the progress in neutrino physics has been impressive leading to the discovery, for the first time, of physics of elementary particle phenom...

Using dispersion relations, we derive the complete virtual QED contributions to Bhabha scattering due to vacuum polarization effects. We apply our result to hadronic corrections and to heavy lepton and top quark loop insertions. We give the first complete estimate of their net numerical effects for both small and large angle scattering at typical beam energies of meson factories, the CERN Large...

Spectrum of elementary string states in type II string theory compactified on a torus contains short multiplets which are invariant under only one quarter of the space-time supersymmetry generators. U -duality transformation converts these states into bound states of Dirichlet branes which wrap around intersecting cycles of the internal torus. We study a class of these bound states that are dua...

Using the OPAL detector at LEP, the running of the effective QED coupling α(t) is measured for space-like momentum transfer, 2 ≤ −t ≤ 6 GeV, from the angular distribution of smallangle Bhabha scattering. This is currently the most significant direct observation of the running of the QED coupling in a single experiment and the first clear evidence of the hadronic contribution to the running in t...