Search results for "CP VIOLATION"

Heavy Neutrinos and Lepton Flavour Violation in Left-Right Symmetric Models at the LHC

2012

We discuss lepton flavour violating processes induced in the production and decay of heavy right-handed neutrinos at the LHC. Such particles appear in left-right symmetrical extensions of the Standard Model as the messengers of neutrino mass generation, and can have masses at the TeV scale. We determine the expected sensitivity on the right-handed neutrino mixing matrix, as well as on the right-handed gauge boson and heavy neutrino masses. By comparing the sensitivity of the LHC with that of searches for low energy LFV processes, we identify favourable areas of the parameter space to explore the complementarity between LFV at low and high energies.

Status of the CPT violating interpretations of the LSND signal

2003

We study the status of the CPT violating neutrino mass spectrum which has been proposed to simultaneously accommodate the oscillation data from LSND, KamLAND, atmospheric and solar neutrino experiments, as well as the non-observation of anti-neutrino disappearance in short-baseline reactor experiments. We perform a three-generation analysis of the global data with the aim of elucidating the viability of this solution. We find no compatibility between the results of the oscillation analysis of LSND and all-but-LSND data sets below 3$\sigma$ CL. Furthermore, the global data without LSND show no evidence for CPT violation: the best fit point of the all-but-LSND analysis occurs very close to a …

Updating neutrino magnetic moment constraints

2016

20 pages.- 4 figures.- Addendum on the limit from the Borexino data

Search for CP violation in D (+/-) -> (KSK +/-)-K-0 and D-s(+/-) -> K-S(0)pi(+/-) decays

2014

A search for \CP violation in Cabibbo-suppressed $D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}$ and $D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}$ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of 3~fb$^{-1}$, recorded by the LHCb experiment. The individual $CP$-violating asymmetries are measured to be \begin{eqnarray*} \mathcal{A}_{CP}^{D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}} & = & (+0.03 \pm 0.17 \pm 0.14) \% \mathcal{A}_{CP}^{D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}} & = & (+0.38 \pm 0.46 \pm 0.17) \%, \end{eqnarray*} assuming that $CP$ violation in the Cabibbo-favoured decays is negligible. A combination of the measured asymmet…

Search for neutral Higgs bosons decaying into four taus at LEP2

2010

A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, β2 = σ(e+e -→Zh)/σSM(e+e-→Zh) ×B(h→aa)×B(a→τ+τ-) 2. For mh 1 is excluded at the 95% confidence level.

The beam and detector for the NA48 neutral kaon CP violation experiment at CERN

2007

The beam and detector, used for the NA48 experiment, devoted to the measurement of Re (ε{lunate}′ / ε{lunate}), and for the NA48/1 experiment on rare KS and neutral hyperon decays, are described. © 2007 Elsevier B.V. All rights reserved.

Do T asymmetries for neutrino oscillations in uniform matter have a CP-even component?

2019

Observables of neutrino oscillations in matter have, in general, contributions from the effective matter potential. It contaminates the CP violation asymmetry adding a fake effect that has been recently disentangled from the genuine one by their different behavior under T and CPT. Is the genuine T-odd CPT-invariant component of the CP asymmetry coincident with the T asymmetry? Contrary to CP, matter effects in uniform matter cannot induce by themselves a non-vanishing T asymmetry; however, the question of the title remained open. We demonstrate that, in the presence of genuine CP violation, there is a new non-vanishing CP-even, and so CPT-odd, component in the T asymmetry in matter, which i…

Signatures of the genuine and matter-induced components of the CP violation asymmetry in neutrino oscillations

2018

CP asymmetries for neutrino oscillations in matter can be disentangled into the matter-induced CPT-odd (T-invariant) component and the genuine T-odd (CPT-invariant) component. For their understanding in terms of the relevant ingredients, we develop a new perturbative expansion in both $\Delta m^2_{21},\, |a| \ll |\Delta m^2_{31}|$ without any assumptions between $\Delta m^2_{21}$ and $a$, and study the subtleties of the vacuum limit in the two terms of the CP asymmetry, moving from the CPT-invariant vacuum limit $a \to 0$ to the T-invariant limit $\Delta m^2_{21} \to 0$. In the experimental region of terrestrial accelerator neutrinos, we calculate their approximate expressions from which we…

New results on kaon decays from NA48

2007

We report on recent results on rare and semileptonic kaon decays from NA48 and NA48/2. Using data from a minimum bias run in 1999 we present a new measurement of the CP violating decay K L → π + π − with over 40000 selected events. We measured the ratio Γ ( K L → π + π − ) / Γ ( K L → π ± e ∓ ν ) = ( 4.835 ± 0.038 ) × 10 −3 leading to the precise determination of the CP violation parameter | η + − | = ( 2.223 ± 0.013 ) × 10 −3 . From the same data we selected over 2 × 10 6 K L → π ± μ ∓ ν decays. Preliminary results from a dalitz plot fit yield the values for the form factors λ + = 0.0260 ± 0.0007 s t a t ± 0.0010 s y s t and λ 0 = 0.0120 ± 0.0008 s t a t ± 0.0015 s y s t . In one month of …

10.8 Conclusion

2008