共查询到20条相似文献,搜索用时 375 毫秒
1.
We examine the effects of mixing induced non-diagonal light-heavy neutrino weak neutral currents on the amplitude for the
process
(with a=e, μ or τ). By imposing constraint that the amplitude should not exceed the perturbative unitarity limit at high energy
, we obtain bounds on light-heavy neutrino mixing parameter sin2
where
is the mixing angle. In the case of one heavy neutrino (mass mξ) or mass degenerate heavy neutrinos, for Λ=1 TeV, no bound is obtained for mξ<0.50 TeV. However, sin2
≤3.8 × 10−6 for mξ=5 TeV and sin
≤6.0 × 10−8 for mξ=10 TeV. For Λ=∞, no constraint is obtained for mξ<0.99 TeV and sin2
≤3.8 × 10−2 (for mξ=5 TeV) and sin2
≤9.6 × 10−3 (for mξ=10 TeV). 相似文献
2.
We present a simple but general treatment of neutrino oscillations in the framework of quantum mechanics, using plane waves and intuitive wave packet principles when necessary. We attempt to clarify some confusing statements that have recently appeared in the literature. 相似文献
3.
4.
Atsuto Suzuki 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2007,83(2):27-38
KamLAND measured the e’s flux from distant nuclear reactors, and found fewer events than expected from standard assumptions about e propagation at the 99.998% confidence level (C.L.). The observed energy spectrum disagrees with the expected spectral shape at 99.6% C.L., and prefers the distortion from neutrino oscillation effects. A two-flavor oscillation analysis of the data from KamLAND and solar neutrino experiments with CPT invariance, yields
eV2 and
. All solutions to the solar neutrino problem except for the large mixing angle (LMA) region are excluded. KamLAND succeeded in detecting geoneutrinos produced by the decays of 238U and 232Th within the Earth. The total observed number of 4.5 to 54.2, assuming a Th/U mass concentration ratio of 3.9 is consistent with 19 predicted by geophysical models. This detection allows better estimation of the abundances and distributions of radioactive elements in the Earth, and of the Earth’s overall heat budget. 相似文献
5.
Takaaki Kajita 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2010,86(4):303-321
Neutrino oscillation was discovered through studies of neutrinos produced by cosmic-ray interactions in the atmosphere. These neutrinos are called atmospheric neutrinos. They are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith-angle and energy dependent deficit of muon-neutrino events. Neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. Neutrino oscillations imply that neutrinos have small but non-zero masses. The small neutrino masses have profound implications to our understanding of elementary particle physics and the Universe. This article discusses the experimental discovery of neutrino oscillations. 相似文献
6.
Srubabati Goswami 《Pramana》2004,62(2):241-253
This article summarises the status of the solar neutrino oscillation phenomenology at the end of 2002 in the light of the
SNO and KamLAND results. We first present the allowed areas obtained from global solar analysis and demonstrate the preference
of the solar data towards the large-mixing-angle (LMA) MSW solution. A clear confirmation in favour of the LMA solution comes
from the KamLAND reactor neutrino data. The KamLAND spectral data in conjunction with the global solar data further narrows
down the allowed LMA region and splits it into two allowed zones a low Δm
2 region (low-LMA) and high Δm
2 region (high-LMA). We demonstrate through a projected analysis that with an exposure of 3 kton-year (kTy) KamLAND can remove
this ambiguity. 相似文献
7.
利用最新的WMAP观测数据推导出电子、Muon和Tau中微子的运动学有效质量的一般上限:e2+μ2+τ2=m12+m22+m32<0.5eV2,或α<0.71eV(其中α=e,μ,τ)。考虑现有中微子振荡的实验数据,进一步得到e<0.24eV以及μ≈τ<0.24eV. 因此有效质量μ和τ太小而无法被探测. 相似文献
8.
Sandip Pakvasa 《Pramana》2004,62(2):347-358
The current status of neutrino anomalies is summarized; the KamLAND experiment is described and the recent results of KamLAND
presented. 相似文献
9.
本文论述2002年诺贝尔物理奖获得者,R.Davis在探测太阳中微子丢失的成就;M.Koshiba在证实存在太阳中微子丢失,探测超新星中微子和大气μ中微子丢失以及证明μ中微子振荡的成就。此外,本文还叙述2002年诺贝尔物理奖给我们的启示。 相似文献
10.
11.
A review of various calculations of the inclusive quasi-elastic reactions and pion production processes in neutrino reactions
for various nuclei at intermediate energies relevant to solar, atmospheric and accelerator neutrinos is presented 相似文献
12.
We analyze the existing solar neutrino experiment data and show the allowed regions. The result from SNO‘s salt phase itself restricts quite a lot the allowed region‘s area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99. 73% C.L. the high-LMA solution is excluded. 相似文献
13.
本文论述2002年诺贝尔物理奖获得者,R.Davis在探测太阳中微子丢失的成就;M.Koshiba在证实存在太阳中微子丢失,探测超新星中微子和大气μ中微子丢失以及证明μ中微子振荡的成就。此外,本文还叙述2002年诺贝尔物理奖给我们的启示。 相似文献
14.
LIU Qiu-Yu CHEN Bo-Lun ZHOU Jie LUO Ming-Jie JING Si-Cong 《理论物理通讯》2005,44(3):505-508
We analyze the existing solar neutrino experiment data and show the allowed regions. The result from SNO's salt phase itself restricts quite a lot the allowed region's area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is excluded. 相似文献
15.
中微子的静质量是20世纪末物理学中一个有待解决的重要问题,它在粒子物理学、宇宙学和天体物理学中占有重要的地位。文章首先评述了太阳中微子实验、大气中微子实验、超新星中微子实验和加速器中微子实验的历史、现状和发展。多年来的实验显示,中微子具有不为零的静质量,可以通过 不同的味之间转换。至少有两个理论描述了中微子振荡,即真空振荡机制和MSW机制,文章讨论了这两个理论及其实验判据。最后,介绍了测量中微子静 相似文献
16.
简要回顾了中微子的发现过程,论述了中微子的基本性质及三种不同类型的中微子,讨论了中微子振荡的最新实验结果及其与中微子静止质量的关系,指出了中微子的静止质量在物理学与天文学中的重要性以及确定中微子的静止质量有待进一步解决的问题。 相似文献
17.
XING Zhi-Zhong ZHANG He 《理论物理通讯》2007,48(3):525-530
In a novel parametrization of neutrino mixing and in the approximation of τ-lepton dominance, we show that the one-loop renormalization-group equations (RGEs) of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tan β, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy. 相似文献
18.
中微子振荡实验——超出标准模型的实验检验(Ⅰ) 总被引:3,自引:0,他引:3
文章总结了中微子振荡实验在历史和现状,介绍了几个太阳中微子丢失实验的结果和几个大气μ中微子丢失实验结果,这些结果表明存在中微子振荡,即中微子具有质量,它是超出标准模型的信号,文章还介绍了21世纪初研究中微子振荡和若干重要实验,噬基线中微子振荡实验以及建造μ子贮存环来产生高能电子中微子束进行中微子振荡的实验以及测量中微子振荡时的CP破坏的设想。 相似文献
19.
B. Mukhopadhyaya S. Raychudhuri K. Agashe B. Allanach D. Bailin B. Brahmachari U. Chattopadhyay D. Choudhury P. Das Amitava Datta Anindya Datta A. Djouadi A. Giri K. Huitu A. Kundu U. Mahanta S. Moretti B. Mukhopadhyaya J. C. Pati A. K. Ray A. Raychaudhuri S. Raychaudhuri P. Roy N. Singh R. Vaidya 《Pramana》2003,60(2):395-399
20.
In a novel parametrization of neutrino mixing and in the approximation of т-lepton dominance, we show that the one-loop renormalization-group equations (RGEs) of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tanβ, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy. 相似文献