At the high luminosity electron-positron circular colliders like FCC-ee in CERN and CEPC in China it will possible to measure very precisely e+e−→Zγ process with subsequent Z decay into particles ...invisible in the detector, that is into three neutrina of the Standard Model and possibly into other weakly coupled neutral particles. Apart from the measurement of the total invisible width (which is not the main subject of this work) this process may be used as a source of Z coupling to electron neutrino – known very poorly. This is possible due to the presence of the t-channel W exchange in the e+e−→νeν¯eγ channel which deforms slightly spectrum of the photon. We are going to show experimental investigation of this effect, for ∼10 inverse atobarn accumulated luminosity, which can provide measurement of the Z−νe coupling with statistical error of order 1%. The estimation of the systematic experimental error will require more work, but most likely it will be of similar size.
We report on high statistics measurements of neutrino energy spectra carried out at 15, 40 and 95 meters from a 2800 Megawatt reactor, using detection modules filled with
6Li-loaded liquid ...scintillator. No oscillations have been observed. Exclusion zones for oscillation parameters are deduced from the observed consistency of the spectra at the three distances. The minimum excluded values of the
δm
2 and sin
22θ parameters are 1 × 10
−2eV
2and 2 × 10
−2 (at 90% CL), respectively.
This document was prepared as part of the briefing material for the Workshop of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May 2006. It gives an overview of the physics ...issues and of the technological challenges that will shape the future of the field, and incorporates material presented and discussed during the Symposium on the European Strategy for Particle Physics, held in Orsay from 30th January to 2nd February 2006, reflecting the various opinions of the European community as recorded in written submissions to the Strategy Group and in the discussions at the Symposium.
We underline the theoretical interest of the vector-vector penguin decay $B_s
\to \phi \phi$, very clean from the experimental point of view. The
CP-violation asymmetry $A_{CP}^{mix}$ comes from the ...interference of mixing and
decay $\lambda_{\phi \phi} = {q \over p} {\bar{A} \over A}$. In the Standard
Model (SM) and in the Naive Factorization limit, the CP phase from the mixing
${q \over p}$ exactly cancels the CP phase from the decay ratio ${\bar{A} \over
A}$. Therefore, this mode is suitable to look for possible New Physics (NP)
because $A_{CP}^{mix}$ would directly indicate the departure from the SM in
mixing. We estimate the deviation from this cancellation by analyzing possible
small effects in the SM, using in particular the QCD Factorization scheme. We
compare the theoretical expectation for $A_{CP}^{mix}$ to the measurement of
LHCb, and the implications for NP. We pay also special attention to the
transverse amplitude $h = -$, the longitudinal and transverse polarization
fractions, and the interesting helicity-dependent observables $\lambda_{\phi
\phi}^{h=0}$ and $\lambda_{\phi \phi}^{h=-}$. On the other hand, we make an
estimation of the expected sensitivity at the future FCCee experiment for the
CP phase and modulus of $\lambda_{\phi \phi}$. We find $\delta(\mid
\lambda_{\phi \phi}\mid) = 0.004$ and $\delta(\phi_{\phi \phi}) = 0.009$ rad
and, comparing to the LHCb data, we point out the expectations at FCCee in the
search of NP.
The Bugey 3 neutrino oscillation experiment has provided high statistics neutrino energy spectra recorded at 15 and 40 meters from a nuclear reactor core. Assuming no oscillations, the measured ...spectra favor a model of reactor spectrum based on the beta spectra measured at ILL.
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