共查询到20条相似文献,搜索用时 15 毫秒
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The partial width of the τ → e - v e v τ can be calculated from the tau mass, lifetime and branching ratio. The increasing precision on these measurements is making the partial width sensitive to the mass of the tau neutrino. We present the tau neutrino mass dependence on the partial width and show that this leads to a limit of m r < 71 MeV at the 95% confidence level. We show that the limit is determined by the uncertainty in the tau lifetime and τ → e?v e v τ branching ratio. Additional measurements of these values are expected in the next few years and we show that the limit could become competitive with the direct measurements. 相似文献
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R. Barate et al. 《The European Physical Journal C - Particles and Fields》1998,2(3):395-406
A bound on the tau neutrino mass is established using the data collected from 1991 to 1995 at with the ALEPH detector. Two separate limits are derived by fitting the distribution of visible energy vs invariant mass
in and decays. The two results are combined to obtain a 95% confidence level upper limit of 18.2 MeV/c on the mass of the tau neutrino.
Received: 30 October 1997 / Published online: 10 March 1998 相似文献
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A critical analysis of the theory of the radiative decays π → ?νγ (?: electron or muon) is given. Earlier results are corrected through a consistent application of gauge invariance and low-energy theorems. Predictions of specific models for the axial-vector form factor are discussed. The paper concludes with remarks on the relate. 相似文献
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《Physics letters. [Part B]》1987,194(4):586-590
A search has been made for the decays of heavy (≈200–500 MeV/c2) neutrinos, νH→νμe, in a 23 m long detector, in the wide-band neutrino beam at the Brookhaven AGS. No significant excess of such events was found and limits are set on the neutrino mixing matrix elements, |UeH|2 and |UμH|2. Results of a more general search for anomalous μe events are also reported. 相似文献
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We investigate prospects of building a future accelerator-based neutrino oscillation experiment in China, including site selection, beam optimization and tau neutrino physics aspects. CP violation, non-unitary mixing and non-standard neutrino interactions are discussed. We simulate neutrino beam setups based on muon and beta decay techniques and compare Chinese laboratory sites by their expected sensitivities. A case study on the Super Proton–Proton Collider and the China JinPing Laboratory is also presented. It is shown that the muon-decay-based beam setup can measure the Dirac CP phase by about 14.2° precision at 1σ CL, whereas non-unitarity can be probed down to ∣αij∣ ≲ 0.37 (i ≠ j = 1, 2, 3) and non-standard interactions to $| {epsilon }_{{ell }{ell }^{prime} }^{m}| lesssim $ 0.11 (${ell }ne {ell }^{prime} =e$, μ, τ) at 90% CL, respectively. 相似文献
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A. Abele et al. 《The European Physical Journal C - Particles and Fields》2001,19(4):667-675
A simultaneous analysis of two different final states from annihilation at rest is used to study the decays of isoscalar states into . The data demand two scalar states, the with , and the with mass and width compatible with previous findings. Apart from the dominant scalar intensity, the (1300) plays an important role in the 5 dynamics. We find a mass of and a width of with a dominant decay into . The decay of the is less than 15% of its decay.
Received: 13 September 2000 / Revised version: 4 January 2001 / Published online: 6 April 2001 相似文献
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《Physics letters. [Part B]》2001,504(3):218-224
The DONUT experiment has analyzed 203 neutrino interactions recorded in nuclear emulsion targets. A decay search has found evidence of four tau neutrino interactions with an estimated background of 0.34 events. This number is consistent with the Standard Model expectation. 相似文献
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An upper limit for the –neutrino mass has been determined from the decay using data collected with the OPAL detector from 1991 to 1995 in collisions at . A limit of 43.2 MeV at 95% CL is obtained using a two–dimensional method in the invariant mass and energy distribution from 22 selected events. Combining this result with OPAL's previously published measurement
using decays, a new combined limit of MeV (95% CL) is obtained.
Received: 15 April 1998 / Published online: 12 August 1998 相似文献
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Hiroyasu Ejiri 《Progress in Particle and Nuclear Physics》2010,64(2):249-257
Neutrino-less double beta decays (0νββ), which violate the lepton number conservation law by ΔL=2, are unique and realistic probes for studying the Majorana nature of neutrinos, the ν mass spectrum and the absolute mass scale, the lepton sector CP and others beyond the standard electro-weak theory. Neutrino nuclear responses (nuclear matrix elements M0ν) are crucial to extract neutrino properties of the particle physics interests from experimental 0νββ rates. Subjects discussed include 0νββ processes and Majorana neutrinos, the present and future 0νββ experiments, and neutrino nuclear responses (M0ν) and charge exchange reactions. 相似文献
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Randall J. Sobie 《Zeitschrift fur Physik C Particles and Fields》1995,69(1):99-105
We present the branching ratio predictions of an isospin statistical model forτ decays to four, five and six pions. Limits on the branching ratios of the three possible six pionτ decay modes using the Conserved Vector Current (CVC) Hypothesis and thee + e ?→6π cross section data are also presented. We find that the isospin model prediction is in good agreement with the well-measured four pion decay modes and consistent with the five pion decay modes. However, we find that some of the recent six pionτ measurements do not agree with the isospin model and the CVC prediction. 相似文献
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Abe K Hayato Y Iida T Ishihara K Kameda J Koshio Y Minamino A Mitsuda C Miura M Moriyama S Nakahata M Obayashi Y Ogawa H Shiozawa M Suzuki Y Takeda A Takeuchi Y Ueshima K Higuchi I Ishihara C Ishitsuka M Kajita T Kaneyuki K Mitsuka G Nakayama S Nishino H Okumura K Saji C Takenaga Y Totsuka Y Clark S Desai S Dufour F Kearns E Likhoded S Litos M Raaf JL Stone JL Sulak LR Wang W Goldhaber M Casper D Cravens JP Kropp WR Liu DW Mine S Regis C Smy MB Sobel HW Vagins MR Ganezer KS Hill JE Keig WE 《Physical review letters》2006,97(17):171801
A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma. 相似文献
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