The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay K(L)-->pi(0)e(+)e(-). This mode is expected to have a significant CP violating component. The measurement of its branching ...ratio could support the standard model or could indicate the existence of new physics. This Letter reports new results from the 1999-2000 data set. One event is observed with an expected background at 0.99+/-0.35 events. We set a limit on the branching ratio of 3.5x10(-10) at the 90% confidence level. Combining with the previous result based on the data set taken in 1997 yields the final KTeV result: BR(K(L)-->pi(0)e(+)e(-))<2.8x10(-10) at 90% C.L.
We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/cΣ−, π− and 540GeV/cp beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± ...correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.
Measurements of the Decay KL-->e+ e- mu+ mu Alavi-Harati, A; Alexopoulos, T; Arenton, M ...
Physical review letters,
2003-Apr-11, 20030411, Letnik:
90, Številka:
14
Journal Article
Recenzirano
The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined ...to be 2.69+/-0.24(stat)+/-0.12(syst)x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.
The $\Xi^0$ muon semileptonic decay has been observed for the first time with nine identified events using the KTeV beam line and detector at Fermilab. The decay is normalized to the $\Xi^0$ beta ...decay mode and yields a value for the ratio of decay rates $\Gamma(\Xi^0 \to \Sigma^+\mu^- \overline{nu}_{\mu})/\Gamma(\Xi^0 \to \Sigma^+e^- \overline{\nu}_e) of 1.8_{-0.5}^{+0.7}(stat)\pm0.2(syst)×10^{-2}$. This is in agreement with the SU(3) flavor symmetric quark model.
The KTeV E799 experiment has conducted a search for the rare decays, K(L)→π(0)π(0)μ(+)μ(-) and K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-), where the X(0) is a possible new neutral boson that was reported by ...the HyperCP experiment with a mass of (214.3 ± 0.5) MeV/c(2). We find no evidence for either decay. We obtain upper limits of Br(K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-)) < 1.0 × 10(-10) and Br(K(L)→π(0)π(0)μ(+)μ(-)) < 9.2 × 10(-11) at the 90% confidence level. This result rules out the pseudoscalar X(0) as an explanation of the HyperCP result under the scenario that the dsX(0) coupling is completely real.
We present an alternative explanation to the reactor antineutrino anomaly through neutrino oscillation induced by the presence of a large flat extra dimension with a size in the sub-micrometer range. ...We also show that the solution is consistent with the other existing oscillation data.
Phys. Rev. D 100, 032003 (2019) We present a measurement of $B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0
\rightarrow \gamma\gamma)$, the Dalitz branching ratio, using data taken in
1999 by the E832 ...KTeV experiment at Fermi National Accelerator Laboratory. We
use neutral pions from fully reconstructed $K_L$ decays in flight; the
measurement is based on about 60 thousand $K_L \rightarrow \pi^0\pi^0\pi^0
\rightarrow \gamma\gamma~\gamma\gamma~e^+e^-\gamma$ decays. We normalize to
$K_L \rightarrow \pi^0\pi^0\pi^0 \rightarrow 6\gamma$ decays. We find $B(\pi^0
\rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma)$ $(m_{e^+e^-}$ >
15 MeV/$c^2)$ = $3.920 \pm 0.016(stat) \pm 0.036 (syst) \times 10^{-3}$.
Using the Mikaelian and Smith prediction for the $e^+e^-$ mass spectrum, we
correct the result to the full $e^+e^-$ mass range. The corrected result is
$B(\pi^0 \rightarrow e^+e^- \gamma)/B(\pi^0 \rightarrow \gamma\gamma) = 1.1559
\pm 0.0047(stat) \pm 0.0106 (syst)$%. This result is consistent with previous
measurements and the uncertainty is a factor of three smaller than any previous
measurement.
We present the status and plans of the Angra Project, a new reactor neutrino oscillation experiment, proposed to be built in Brazil at the Angra dos Reis nuclear complex. This experiment is aimed to ...measure theta13, the last unknown of the three neutrino mixing angles. We propose a high sensitivity multi-detector experiment, able to reach a sensitivity to antineutrino disappearance down to sin² 2theta13 = 0.006 in a three years running period, by combining a high luminosity design, very low background from cosmic rays and careful control of systematic errors. We also intend to explore the possibility to use the neutrino detector for purposes of safeguards and non-proliferation of nuclear weapons.
The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP ...experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) < 1.0 x 10^{-10} and Br(KL->pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real.
PDF
