1,420 research outputs found

    Discrete Symmetries CP, T, CPT

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    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

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    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

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    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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