1,432 research outputs found
Discrete Symmetries CP, T, CPT
The role of Symmetry Breaking mechanisms to search for New Physics is of
highest importance. We discuss the status and prospects of the Discrete
Symmetries CP, T, CPT looking for their separate Violation in LHC experiments
and meson factories.Comment: 9 pages, 5 figures; Jagiellonian Symposium on Fundamental and Applied
Subatomic Physic
The neutrino charge radius in the presence of fermion masses
We show how the crucial gauge cancellations leading to a physical definition
of the neutrino charge radius persist in the presence of non-vanishing fermion
masses. An explicit one-loop calculation demonstrates that, as happens in the
massless case, the pinch technique rearrangement of the Feynman amplitudes,
together with the judicious exploitation of a fundamental current relation
leads to a completely gauge independent definition of the effective neutrino
charge radius. Using the formalism of the Nielsen identities it is further
proved that the same cancellation mechanism operates unaltered to all orders in
perturbation theory.Comment: 26 pages, 8 figure
The CP-Conserving Direction
A symmetry transformation is well defined in the case of an invariant theory,
being the corresponding operator undetermined otherwise. However, we show that,
even with CP violation, it is possible to determine the CP transformation by
separating the Lagrangian of the Standard Model in a CP-conserving and a
CP-violating part, in a unique way, making use of the empirically known quark
mixing hierarchy. To order \lambda^3 for the Bd-system, the CP-conserving
direction matches one of the sides of the (bd) unitarity triangle. We use this
determination to calculate the rephasing invariant parameter \epsilon, which
measures CP-mixing in the B0-B0bar system.Comment: 12 pages, no figure. Version to appear in JHE
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