共查询到20条相似文献,搜索用时 109 毫秒
1.
Yu. A. Gornushkin 《Physics of Particles and Nuclei》2011,42(4):553-557
The OPERA experiment at the underground Gran Sasso Laboratory (LNGS) has to perform the first detection of neutrino oscillations
in appearance mode through the direct observation of νμ → ντ. The apparatus consists of a lead/emulsion-film target complemented by electronic detectors. It is placed in the high-energy,
long-baseline CERN neutrino beam (CNGS) 730 km away from the neutrino source. Runs with CNGS neutrinos were successfully carried
out in 2008–2009 with the first candidate event νμ → gvτ recently detected. 相似文献
2.
In the framework of a left–right model containing mirror fermions with gauge group SU(3)
C
⊗SU(2)
L
⊗SU(2)
R
⊗U(1)
Y′, we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate
the decay rates of the Lepton Flavor Violation (LFV) processes μ→eγ, τ→μγ and τ→eγ. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We
also estimate the decay rates of heavy Majorana neutrinos in the channels N→W
±
l
∓, N→Zν
l
and N→Hν
l
, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass
matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the
double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing
a symmetric mixing of electron neutrino with muon and tau neutrinos leads to tri-bimaximal mixing matrix for light neutrinos. 相似文献
3.
Current data implies three simple forms of the neutrino mass matrix, each corresponding to the conservation of a nonstandard
lepton charge. While models based on L
e and L
e-L
μ-L
τ are well known, little attention has been paid to L
μ-L
τ. A low-energy mass matrix conserving L
μ-L
τ implies quasidegenerate light neutrinos. Moreover, it is μ-τ symmetric and therefore (in contrast to L
e and L
e-L
μ-L
τ) automatically predicts maximal atmospheric neutrino mixing and zero U
e3. A seesaw model based on L
μ-L
τ is investigated and testable predictions for the neutrino mixing observables are given. Renormalization group running below
and in between the seesaw scales is taken into account in our analysis, both numerically and analytically.
The text was submitted by the authors in English. 相似文献
4.
R. N. Mohapatra 《Pramana》2004,63(6):1295-1306
Many experiments are being planned to measure the neutrino mixing angles more precisely. In this note, the theoretical significance
of a high precision measurement of these parameters is discussed. It is emphasized that they can provide crucial information
about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining
the neutrino mass matrix. They may also be able to throw light on the question of lepton-quark unification as well as the
existence of any leptonic symmetries. For instance if exact μ↔ τ symmetry in the neutrino mass matrix is assumed to be the reason for maximalv
μ-vgt mixing, one gets θ13 = 0 and {ie1295-01} can provide information about the way the μ↔ τ symmetry breaking manifests in the case of normal hierarchy. 相似文献
5.
Yoshio Koide 《The European Physical Journal C - Particles and Fields》2007,50(4):809-816
Based on the universal seesaw mass matrix model with the three scalars φi, and by assuming S3 flavor symmetry for the Yukawa interactions, the lepton masses and mixings are investigated systematically. In order to understand
the observed neutrino mixing, the charged leptons (e,μ,τ) are regarded as the three objects (e1,e2,e3) of S3, while the neutrino mass eigenstates are regarded as the irreducible representation (νη,νσ,νπ) of S3, where (νπ,νη) and νσ are a doublet and a singlet, respectively, which are composed of the three objects (ν1,ν2,ν3) of S3. 相似文献
6.
Kh. M. Beshtoev 《Physics of Particles and Nuclei Letters》2007,4(6):471-476
In the standard theory of neutrino oscillations, it is supposed that physically observed neutrino states ν
e
, νμ, ντ, have no definite masses, that they are initially produced as a mixture of the ν1, ν2, ν3 neutrino states (i.e., they are produced as a wave packet), and that neutrino oscillations are the real ones. Then, this
wave packet must decompose at a definite distance into constituent parts and neutrino oscillations must disappear. It was
shown that these suppositions lead to violation of the law of energy and momentum conservation. An alternative scheme of neutrino
oscillations obtained within the framework of particle physics has been considered, where the above mentioned shortcomings
are absent, the oscillations of neutrinos with equal masses are the real ones, and the oscillations of neutrinos with different
masses are the virtual ones. Expressions for probabilities of neutrino transitions (oscillations) in the alternative (corrected)
scheme are given.
The text was submitted by the author in English. 相似文献
7.
Yu. I. Romanov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):818-820
The flavor composition of the solar beryllium neutrino was analyzed using schemes that include the new (heavy) neutrino (ν4) at a negligible angle of mixing with the light partners ν
e
, νμ, and ντ. 相似文献
8.
We investigate symmetries in Dirac and Majorana mass matrices of neutrinos in a three-generation scenario. We show that if
we invokeL
e +L
μ-L
τ
x
S
2R symmetry, one combination of right-handed neutrino states remains massless which can be interpreted as a sterile neutrino.
Next we consider a SU2L
x U(1)y
x U(l)R gauge model and show how higher-dimensional operators can induce mixing between left- and right-handed states which explains
solar, atmospheric and LSND experimental results. 相似文献
9.
C. Jollet 《Physics of Atomic Nuclei》2006,69(11):1872-1875
The aim of the OPERA experiment is to provide unambiguous evidence for the ν
μ ↔ ν
τ oscillation by looking at the appearance of ν
τ in a pure ν
μ beam. This oscillation will be sought in the region of the oscillation parameters indicated by the atmospheric neutrino results.
The experiment is part of the CNGS (CERN Neutrino beam to Gran Sasso) project. The ν
μ beam produced at CERN will be sent towards the Gran Sasso underground laboratory, where the OPERA detector is under construction.
The detector, the physics potential, and performance for neutrino oscillation studies including the subleading ν
μ ↔ ν
ε search are presented.
The text was submitted by the author in English. 相似文献
10.
A.E. Ball A. Braem L. Camilleri A. Catinaccio G. Chelkov F. Dydak A. Elagin P.K. Frandsen M. Gostkin A. Grant A. Guskov C. Joram Z. Krumshteyn H. Müller H. Postema M. Price T. Rovelli D. Schinzel J. Séguinot G. Valenti R. Voss J. Wotschack A. Zhemchugov 《The European Physical Journal C - Particles and Fields》2007,49(4):1117-1142
Today’s greatest challenge in accelerator-based neutrino physics is to measure the mixing angle θ13 which is known to be much smaller than the solar mixing angle θ12 and the atmospheric mixing angle θ23. A non-zero value of the angle θ13 is a prerequisite for observing CP violation in neutrino mixing. In this paper, we discuss a deep-sea neutrino experiment
with 1.5 Mt fiducial target mass in the Gulf of Taranto with the prime objective of measuring θ13. The detector is exposed to the CERN neutrino beam to Gran Sasso in off-axis geometry. Monochromatic muon neutrinos of ≈
800 MeV energy are the dominant beam component. Neutrinos are detected through quasi-elastic, charged-current reactions in
sea water; electrons and muons are detected in a large-surface, ring-imaging Cherenkov detector. The profile of the seabed
in the Gulf of Taranto allows for a moveable experiment at variable distances from CERN, starting at 1100 km. From the oscillatory
pattern of the disappearance of muon neutrinos, the experiment will measure sin2θ23 and especially Δm2
23 with high precision. The appearance of electron neutrinos will be observed with a sensitivity to P(νμ→νe) as small as 0.0035 (90% CL) and sin2θ13 as small as 0.0019 (90% CL; for a CP phase angle δ=0° and for normal neutrino mass hierarchy). 相似文献
11.
A.S. Joshipura S.D. Rindani 《The European Physical Journal C - Particles and Fields》2000,14(1):85-89
We discuss an extended model which naturally leads to mass scales and mixing angles relevant for understanding both the solar and atmospheric neutrino
anomalies in terms of the vacuum oscillations of the three known neutrinos. The model uses a softly broken –– symmetry and contains a heavy scale GeV. The –– symmetric neutrino masses solve the atmospheric neutrino anomaly while breaking of –– generates the highly suppressed radiative mass scale needed for the vacuum solution of the solar neutrino problem. All the neutrino masses in the model are inversely related
to , thus providing seesaw-type of masses without invoking any heavy right-handed neutrinos. The possible embedding of the model
into an SU(5) grand unified theory is discussed.
Received: 5 August 1999 / Revised version: 18 November 1999 / Published online: 6 April 2000 相似文献
12.
Sarira Sahu W.-Y. P. Hwang 《The European Physical Journal C - Particles and Fields》2008,58(4):609-615
We have calculated the effective potential experienced by highly relativistic neutrinos in a weakly magnetized electron–positron
plasma, where a momentum-dependent finite-width correction to the propagator of W is considered to account for the threshold effect. Magnetars are believed to be sources of TeV–PeV neutrinos which are produced
due to photomeson and proton–proton interactions in their atmosphere. We have studied the resonant-oscillation process ν
e
↔
ν
μ,τ
of the highly relativistic neutrinos in the atmosphere of SGR 1806-20, which is a magnetar. It is shown that, for high-energy
neutrinos propagating within the magnetar atmosphere, the resonance condition can never be satisfied. On the other hand, if
GeV neutrinos are produced deep inside the magnetar atmosphere, where the temperature is about 50 keV or more, then these
neutrinos can undergo resonant oscillation. 相似文献
13.
Results from Super-Kamiokande-I’s entire 1496 live days of solar neutrino data are presented, including the absolute flux,
energy spectrum, zenith angle (day/night) and seasonal variation. The possibility of MSW and vacuum oscillations is discussed
in light of these results. Results from the first 1289 days of Super-K-I’s atmospheric neutrino analysis are also presented,
including the evidence for νμ →ν
τ oscillations, against νμ → νsterile oscillations, and the current limits on proton decay. Finally, results based on 56 × 1019 protons on target are given for the K2K long-baseline neutrino oscillation experiment. 相似文献
14.
Summary In this paper we have estimated the sensitivity of a large-mass liquid-scintillation detector to search for supernova neutrinos
of different flavours. Events produced by νμ and ντ interactions can be identified by looking at the distorsion in the neutrino energy spectrum. We have shown here that, overlapped
to the main energy distribution produced by
interactions with protons a peak at 15.11 MeV (due to the de-excitation of12C* nuclei excited by neutral-current neutrino interactions) gives a possible signature of these neutrino flavours.
Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction. 相似文献
15.
Riazuddin 《The European Physical Journal C - Particles and Fields》2007,51(3):697-699
It is proposed that light neutrinos form a triplet in a global SU(3) symmetry in the mass eigenstate basis. Assuming that
the SU(3) symmetry is broken in the direction , and after going to the flavor basis, we predict the atmospheric mixing angles sin2θ23=0.5 and sinθ13=0, if νμ–ντ symmetry is assumed. In the flavor basis, the diagonal part of the matrix coefficient of b (the dominant part) is found to
transform like . Imposing the same condition on the matrix coefficient of a fixes the solar mixing angle, . The implications for neutrinoless double beta decay are discussed. 相似文献
16.
Takeshi Araki Ryo Takahashi 《The European Physical Journal C - Particles and Fields》2009,63(4):521-526
We investigate the Friedberg–Lee (FL) symmetry and its promotion to include the μ–τ symmetry, and call this the twisted FL symmetry. Based on the twisted FL symmetry, two possible schemes are presented toward
the realistic neutrino mass spectrum and the tri-bimaximal mixing. In the first scheme, we suggest the semi-uniform translation
of the FL symmetry. The second one is based on the S
3 permutation family symmetry. The breaking terms, which are twisted FL symmetric, are introduced. Some viable models in each
scheme are also presented. 相似文献
17.
Yu. I. Romanov 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(4):507-510
Electroweak and electromagnetic contributions to the spectrum of beryllium solar neutrinos scattered by an electron are investigated.
The flavor structure of the electroweak spectrum with the content of electron neutrinos and admixture components ν
μ and ν
τ is analyzed. 相似文献
18.
《Physics of Atomic Nuclei》2004,67(6):1161-1171
The present status of the Baikal Neutrino Experiment and the present results of a search for upward going atmospheric neutrinos,
WIMPs, and magnetic monopoles obtained with the NT-200 detector are reviewed. The results of a search for very high-energy
neutrinos are presented as well. An upper limit on the ν
e
+ν
e
+ν
τ
neutrino diffuse flux of E
2Φ(E)<1.3×10−6 cm−2 s−1 sr−1 GeV within a neutrino energy range of 104–107 GeV is obtained, assumingan E
−2 behavior of the neutrino spectrum and a flavor ratio ν
e
:ν
π
:ν
τ
=1:1:1. We also describe the moderate upgrade of the NT-200 planned for the next few years and present a possible detector
on the Gigaton scale.
From Yadernaya Fizika, Vol. 67, No. 6, 2004, pp. 1186–1194.
Original English Text Copyright ? 2004 by Aynutdinov, Balkanov, Belolaptikov, Bezrukov, Budnev, Chensky, Chernov, Danilchenko,
Dzhilkibaev, Domogatsky, Dyachok, Gaponenko, O. Gress, T. Gress, Klabukov, Klimov, Klimushin, Konischev, Koshechkin, Kulepov,
Kuzmichev, Kuznetzov, Lubsandorzhiev, Mikheyev, Milenin, Mirgazov, Moiseiko, Osipova, Panfilov, G. Pan'kov, L. Pan'kov, Parfenov,
Pavlov, Pliskovsky, Pokhil, Polecshuk, Popova, Prosin, Rosanov, Rubtzov, Semeney, Shaibonov, Spiering, Streicher, Tarashansky,
Vasiliev, Vyatchin, Wischnewski, Yashin, Zhukov.
This article was submitted by the authors in English. 相似文献
19.
Starting with the unification hypothesis of mixings of quarks and leptons and small quark-like mixings at the see-saw scale,
we find that two large mixings for νe —νx03BC; andv
μ—v
τ at the weak scale are obtained as a result of renormalization group evolution and radiative magnification if the three neutrinos
are quasi degenerate in masses and possess the same CP parity. We also find thatU
e3
remains small and well within the CHOOZ-Palo Verde bound since the correspondingV
ub
for CKM mixing is very small. Several testable pedictions are pointed out. 相似文献
20.
B. Moussallam 《The European Physical Journal C - Particles and Fields》2008,53(3):401-412
We discuss matrix elements of the strangeness changing vector current using their relation, due to analyticity, with πK scattering
in the P-wave. We take into account experimental phase-shift measurements in the elastic channel as well as results, obtained
by the LASS collaboration, on the details of inelastic scattering, which show the dominance of two quasi-two-body channels
at medium energies. The associated form factors are shown to be completely determined, up to one flavor symmetry breaking
parameter, imposing boundary conditions at t=0 from chiral and flavor symmetries and at t→∞ from QCD. We apply the results
to the τ→Kπντ and τ→Kππντ amplitudes and compare the former to recent high statistics results from B factories.
PACS 11.55.Fv; 11.30.Rd; 11.30.Hv; 13.35.Dx 相似文献