Search results for "Symmetries"
showing 10 items of 84 documents
Probing CPT in transitions with entangled neutral kaons
2015
In this paper we present a novel CPT symmetry test in the neutral kaon system based, for the first time, on the direct comparison of the probabilities of a transition and its CPT reverse. The required interchange of in ↔ out states for a given process is obtained exploiting the Einstein-Podolsky-Rosen correlations of neutral kaon pairs produced at a ϕ-factory. The observable quantities have been constructed by selecting the two semileptonic decays for flavour tag, the ππ and 3π 0 decays for CP tag and the time orderings of the decay pairs. The interpretation in terms of the standard Weisskopf-Wigner approach to this system, directly connects CPT violation in these observables to the violati…
Present status of chiral perturbation theory
2005
6 páginas, 1 tabla.-- Comunicación presentada en el 10º International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2004) celebrado del 29 de Agosto al 4 de Septiembre de 2004 en Beijing (China).-- arXiv:hep-ph/0410322v1
Topological structure of dense hadronic matter
2007
8 pages, 4 figures.-- ISI Article Identifier: 000244425500052.
Minimal Flavour Violation and Multi-Higgs Models
2010
We propose an extension of the hypothesis of Minimal Flavour Violation (MFV) to general multi-Higgs models without the assumption of Natural Flavour Conservation (NFC) in the Higgs sector. We study in detail under what conditions the neutral Higgs couplings are only functions of V-CKM and propose a MFV expansion for the neutral Higgs couplings to fermions
Direct test of time reversal symmetry in the entangled neutral kaon system at a phi-factory
2013
We present a novel method to perform a direct T (time reversal) symmetry test in the neutral kaon system, independent of any CP and/or CPT symmetry tests. This is based on the comparison of suitable transition probabilities, where the required interchange of in out states for a given process is obtained exploiting the Einstein-Podolski-Rosen correlations of neutral kaon pairs produced at a phi-factory. In the time distribution between the two decays, we compare a reference transition like the one defined by the time-ordered decays (l(-), pi pi) with the T-conjugated one defined by (3 pi(0), l(+)). With the use of this and other T-conjugated comparisons, the KLOE-2 experiment at DA Phi NE co…
Neutrino masses and mixing in A(4) models with three Higgs doublets
2013
We study neutrino masses and mixing in the context of flavor models with A(4) symmetry, three scalar doublets in the triplet representation, and three lepton families. We show that there is no representation assignment that yields a dimension-5 mass operator consistent with experiment. We then consider a type-I seesaw with three heavy right-handed neutrinos, explaining in detail why it fails, and allowing us to show that agreement with the present neutrino oscillation data can be recovered with the inclusion of dimension-3 heavy neutrino mass terms that break softly the A(4) symmetry.
Sensitivity to the Higgs sector of SUSY-seesaw models via LFV tau decays
2009
4 páginas, 3 figuras.-- PACS: 11.30.Hv, 12.60.Jv, 14.60.St.-- El PDF es la versión pre-print (arXiv:0909.0724v1).-- Trabajo presentado en la 7th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY09).
Beam-Helicity Asymmetries in Double-Pion Photoproduction off the Proton
2009
Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels $\vec{\gamma}p\to \pi^{+}\pi^0n$, $\vec{\gamma}p\to \pi^{0}\pi^0p$ and $\vec{\gamma}p\to \pi^{+}\pi^{-}p$ . The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of $\pi^0$ mesons were detected in a $~4\pi$ electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. The precisely measured asymmetries are very sensitive to details of the production processes and are thus key observables in the modeling of the reaction d…
What can be learned from the Belle spectrum for the decay τ−→ντKSπ−
2008
Abstract A theoretical description of the differential decay spectrum for the decay τ − → ν τ K S π − , which is based on the contributing Kπ vector and scalar form factors F + K π ( s ) and F 0 K π ( s ) being calculated in the framework of resonance chiral theory (R χ T), additionally imposing constraints from dispersion relations as well as short distance QCD, provides a good representation of a recent measurement of the spectrum by the Belle Collaboration. Our fit allows to deduce the total branching fraction B [ τ − → ν τ K S π − ] = 0.427 ± 0.024 % by integrating the spectrum, as well as the K ∗ resonance parameters M K ∗ = 895.3 ± 0.2 MeV and Γ K ∗ = 47.5 ± 0.4 MeV , where the last t…
Constraining multi-Higgs flavour models
2014
To study a flavour model with a non-minimal Higgs sector one must first define the symmetries of the fields; then identify what types of vacua exist and how they may break the symmetries; and finally determine whether the remnant symmetries are compatible with the experimental data. Here we address all these issues in the context of flavour models with any number of Higgs doublets. We stress the importance of analysing the Higgs vacuum expectation values that are pseudo-invariant under the generators of all subgroups. It is shown that the only way of obtaining a physical CKM mixing matrix and, simultaneously, non-degenerate and non-zero quark masses is requiring the vacuum expectation value…