共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
A. G. Beda V. B. Brudanin E. V. Demidova C. Vylov M. G. Gavrilov V. G. Egorov A. S. Starostin M. V. Shirchenko 《Physics of Atomic Nuclei》2007,70(11):1873-1884
The first result obtained in the measurements of the neutrino magnetic moment at the Kalinin nuclear power plant with the GEMMA spectrometer is presented. A high-purity germanium detector of mass 1.5 kg placed at a distance of 13.9 m from the reactor core is used in the spectrometer. The antineutrino flux at the detector position is 2.73 × 1013 $ \bar \nu The first result obtained in the measurements of the neutrino magnetic moment at the Kalinin nuclear power plant with the
GEMMA spectrometer is presented. A high-purity germanium detector of mass 1.5 kg placed at a distance of 13.9 m from the reactor
core is used in the spectrometer. The antineutrino flux at the detector position is 2.73 × 1013
/(cm2 s). The differential method is used to select events of electromagnetic antineutrino-electron scattering. The spectra taken
in the reactor-on and reactor-off modes over 6200 and 2064 h, respectively, are compared. On the basis of a data analysis,
an upper limit of 5.8 × 10−11 μB was set on the neutrino magnetic moment μ
ν
at a 90% C.L.
Original Russian Text ? A.G. Beda, V.B. Brudanin, E.V. Demidova, C.Vylov, M.G. Gavrilov, V.G. Egorov, A.S. Starostin, M.V.
Shirchenko, 2007, published in Yadernaya Fizika, 2007, Vol. 70, No. 11, pp. 1925–1935. 相似文献
3.
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
4.
V. V. Skobelev 《Journal of Experimental and Theoretical Physics》1997,85(1):13-16
We consider axion formation processes in the synchrotron (e
−→e
−
a) and annihilation (e
−
e
+→a) channels in a constant crossed field F
μν
Fμν=Fμν*F
μν
=0, which approximates constant fields of other configurations in the ultrarelativistic asymptotic limit. The probability
and intensity of axion emission are obtained, and we analyze the energy and field asymptotics. A comparison with the characteristic
neutrino channel
yields the constraints on the axion mass and the energy scale for Peccei-Quinn symmetry breaking. Possible astrophysical
applications are discussed.
Zh. éksp. Teor. Fiz. 112, 25–31 (July 1997) 相似文献
5.
A multiple production study of neutral strange particles in νμ charged current interactions has been performed using the full data sample from the NOMAD experiment. This analysis allows
one to investigate the mechanisms of strange particle production in neutrino interactions. In this study we have tried to
build a model for the production of strange particles, which would allow us to describe our measured rates of neutral strange
particles, as well as the rates of the single-, double-and triple-V
0 production: Λ, K
0,
, K
0
K
0, ΛK
0, Λ
, K
0
, ΛΛ, and K
0
K
0
K
0.
The text was submitted by the authors in English. 相似文献
6.
A discussion is given on the prospects for making a precise determination of the value of sin2θ W (θW is the Weinberg angle) and for improving the sensitivity of the search for the antineutrino magnetic moment to ≈1.5×10−11μB and for the
mixing parameter to sin22θ ≈10−2 by measuring in a single experiment the cross sections for
scattering for the reaction
. Such an experiment with ∼100 000 events/yr detected for each reaction can be carried out, for example, using the BOREXINO
detector and an approximately 10 MCi 90Sr source.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 435–439 (10 April 1998) 相似文献
7.
N. M. Agababyan V. V. Ammosov M. Atayan N. Grigoryan H. Gulkanyan A. A. Ivanilov Zh. Karamyan V. A. Korotkov 《Physics of Atomic Nuclei》2006,69(1):35-38
The influence of nuclear effects on the production of neutral strange particles (V
0) is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with E
v
=3−30 GeV) at the Serpukhov accelerator. The mean multiplicity of V
0 particles in nuclear interactions,
, is found to exceed significantly that in “quasideuteron” interactions,
. The ratio of
is larger than that for π− mesons,
. It is shown that the multiplicity gain of V
0 particles can be explained by intranuclear interactions of produced pions.
The text was submitted by the authors in English. 相似文献
8.
Xue-Qian Li Yong Liu Zheng-Tao Wei Liang Tang 《The European Physical Journal C - Particles and Fields》2008,56(1):97-103
In a new measurement on neutrino oscillations, νμ→νe, the MiniBooNE Collaboration observes an excess of electron-like events at low energy and the phenomenon may demand an explanation
that obviously is beyond the oscillation picture. We propose that the heavier neutrino, ν2, decaying into a lighter one, ν1, via the transition process νμ→νe+X, where X denotes any light products, could be a natural mechanism. The theoretical model we employ here is the unparticle
scenario established by Georgi. We have studied two particular modes and νμ→νe+ν̄e+νe. Unfortunately, the number coming out of the computation is too small to explain the observation. Moreover, our results are
consistent with the cosmology constraint on the neutrino life time and the theoretical estimation made by other groups; therefore,
we can conclude that even though neutrino decay seems plausible in this case, it indeed cannot be the source of the peak at
lower energy observed by the MiniBooNE Collaboration and there should be other mechanisms responsible for the phenomenon. 相似文献
9.
A. N. Ivanov H. Oberhummer N. I. Troitskaya M. Faber 《The European Physical Journal A - Hadrons and Nuclei》2000,8(2):223-250
A dynamics of low-energy nuclear forces is investigated for low-energy electromagnetic and weak nuclear reactions with the
deuteron in the Nambu-Jona-Lasinio model of light nuclei by example of the neutron-proton radiative capture (M1-capture) n
+ p → D + γ, the photomagnetic disintegration of the deuteron γ + D → n + p and weak reactions of astrophysical interest. These are the solar proton burning p + p → D + e+ + ν
e, the pep-process p + e− + p → D + ν
e and the neutrino and antineutrino disintegration of the deuteron caused by charged ν
e + D → e− + p + p, + D → e+ + n + n and neutral ν
e() + D → ν
e() + n + p weak currents. 相似文献
10.
Jogesh C. Pati 《Pramana》2004,62(2):513-522
Evidence in favor of supersymmetric grand unification including that based on the observed family multiplet-structure, gauge
coupling unification, neutrino oscillations, baryogenesis, and certain intriguing features of quark-lepton masses and mixings
is noted. It is argued that attempts to understand (a) the tiny neutrino masses (especially Δm
2(v
2 – v3)), (b) the baryon asymmetry of the Universe (which seems to need leptogenesis), and (c) the observed features of fermion
masses such as the ratiom
b/mτ, the smallness ofV
cb and the maximality of
seem to select out the route to higher unification based on an effective string-unifiedG(224) =SU(2)L ×SU(2)R ×SU(2)c orSO(10)-symmetry that should be operative in 4D, as opposed to other alternatives. A predictiveSO(10)/G(224)-framework possessing supersymmetry is presented that successfully describes the masses and mixings of all fermions including
neutrinos. It also accounts for the observed baryon asymmetry of the Universe by utilizing the process of leptogenesis, which
is natural to this framework. It is argued that a conservative upper limit on the proton lifetime within thisSO(10)/G(224)-framework, which is so far most successful, is given by
x 1034 years. This in turn strongly suggests that an improvement in the current sensitivity by a factor of five to ten (compared
to SuperK) ought to reveal proton decay. Implications of this prediction for the next-generation nucleon decay and neutrino-detector
are noted. 相似文献
11.
12.
Influence of ion-molecular reactions on μ-capture in hydrogen and on fusion in 3Hedμ muonic molecule
The de-excitation processes (J=1)→ (J=0) in muonic molecular ions (ppμ)+ and (3Hedμ)+ are studied. It is shown that the rate of such transitions substantially depends on the chain of ion-molecular reactions
initiated by positively charged muonic ions.
The probabilities of ortho-para transition in the [(ppμ)+H2] and [(ppμ)+e] complexes formed as a result of chemical reactions in the pure hydrogen were estimated.
Taking into account the ion-molecular processes in D2 + He mixtures, the evaluation of the observed rate λf of nuclear fusion in the 3Hedμ muonic molecules was performed. The expected yield of fusion reactions per muon at the mixture density φ=0.1 and concentration
C
He
=0.05 was obtained to be equal to
.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
Defining the ratiosr
p
=σ(vp →vx)/σ(vp →μ
−
x) and
we obtain the bounds 0.28 ⩽r
p
⩽ 0.61 and
using only the parton model and the data of CDHS group with iron target. We also give the complete set of parton-model relations
which would allow the determination of all the neutral-current coupling constants from inclusive cross sections alone. 相似文献
14.
Itzhak Goldman 《International Journal of Theoretical Physics》1982,21(8-9):665-672
Dirac’s large number hypothesis (LNH), in the formG/G
0=HH
0
−1
, is applied to the matter-dominated cosmological era, using the framework of the scale covariant theory (Canuto et al., 1977).
We obtain explicit expressions forR andβ
a
as functions ofR
E
, whereR andR
E
are the scale factors of the cosmological Robertson-Walker metric, expressed in atomic and gravitational units, respectively,
andβ
a
is the ratio between the rates of gravitational and atomic clocks. The parameters in these expressions are
, the deceleration parameter in gravitational units, and
(t
0)H
0
−1
where
(t
0) is the present epoch value of the derivative ofβ
a
with respect to atomic time. We find that a necessary condition for the LNH to be compatible with a Robertson-Walker model
is that
(t
0)H
0
−1
≥
2
1
. The only experimental values for
(t
0) available at present are those based on the lengthening of the Moon’s period of revolution around the Earth, suggesting
0.86≥
(t
0)H
0
−1
≥0.21; the more promising technique of radar ranging to the inner planets has not yet produced a value for
(t
0). Using the lunar data, it follows that 0≤
≲0.42 corresponding to an open universe (k=−1). Closed models (k=1,
>1/2) are not compatible with the LNH since the required values of
(t
0)H
0
−1
are more than an order of magnitude above the observational upper limit.
Presented at the Dirac Symposium, Loyola University, New Orleans, 1981. 相似文献
15.
R N Mohapatra 《Pramana》2006,67(5):783-791
See-saw mechanism has been a dominant paradigm in the discussion of neutrino masses. We discuss how this idea can be tested
via a baryon number violating process such as N-
oscillation. Since the expected see-saw scale is high and the N-
amplitude goes like M
R
−5
, one might think that this process is not observable in realistic see-saw models for neutrino masses. In this talk I show
that in supersymmetric models, the above conclusion is circumvented leading to an enhanced and observable rate for N
oscillation. I also discuss a new mechanism for baryogenesis in generic models for neutron-anti-neutron oscillation. 相似文献
16.
N. M. Panyunin 《Russian Journal of Mathematical Physics》2007,14(4):501-504
In the note, a Smolyanov-Shavgulidze model of infinite-dimensional superspace H
Λ = Λ0
H
0 ⊕ Λ1
H
1 corresponding to a Hilbert space H = H
0 ⊕ H
1 over a Hilbert superalgebra Λ = Λ0 ⊕ Λ1 is considered. Its relation to the Khrennikov superspace is discussed. Moreover, H
Λ is equipped with the structure of Hilbert superspace with an inner superproduct (·, ·)Λ. The supermeasures are defined as Λℂ
(∧H
1)-valued measures on H
0 (Λℂ stands for the complexification of Λ). The definition of the Fourier supertransform is similar to the ordinary one,
(y) =
μ(dz). It turns out that the values of the Fourier supertransform of a supermeasure on the subspace
= H
0 ⊕ Λ1
H
1 can be obtained by applying a certain operator to the values of the classical Fourier transform. The main result is the theorem
claiming that the Fourier supertransform of supermeasures is isometric on superspaces with zero even part (H
0 = {0}). As a corollary, we note that the operator of Fourier supertransform is injective. We also give necessary and sufficient
conditions for the countable additivity of cylindrical supermeasures in terms of continuity of their Fourier supertransforms
(an analog of the Minlos-Sazonov theorem). 相似文献
17.
We have investigated the proof of the H theorem within a
manifestly covariant approach by considering the relativistic
statistical theory developed in [G. Kaniadakis, Phys. Rev. E 66, 056125 (2002); G. Kaniadakis, Phys. Rev. E 72, 036108 (2005)]. As it
happens in the nonrelativistic limit, the molecular chaos hypothesis
is slightly extended within the Kaniadakis formalism. It is shown
that the collisional equilibrium states (null entropy source term)
are described by a κ power law generalization of the
exponential Juttner distribution, e.g.,
,
with θ=α(x)+βμpμ, where α(x) is a
scalar, βμ is a four-vector, and pμ is the
four-momentum. As a simple example, we calculate the relativistic
κ power law for a dilute charged gas under the action of an
electromagnetic field Fμν. All standard results are readly
recovered in the particular limit κ→0. 相似文献
18.
G. Abbiendi et al. 《The European Physical Journal C - Particles and Fields》2006,45(2):307-335
The mass and width of the W boson are measured using e+e– → W+W– events from the data sample collected by the OPAL experiment at LEP at centre-of-mass energies between 170 GeV and 209 GeV.
The mass (mW) and width (ΓW) are determined using direct reconstruction of the kinematics of W+W– →
and W+W– →
events. When combined with previous OPAL measurements using W+W– →
events and the dependence on of the WW production cross-section at threshold, the results are determined to be
where the first error is statistical, the second systematic and the third due to uncertainties in the value of the LEP beam
energy. By measuring in the channel using several different determinations of the direction of jets with differing sensitivities
to soft particles, a limit is also obtained on possible final-state interactions due to colour reconnection effects inW+W– →
events. The consistency of the results for the W mass and width with those inferred from other electroweak parameters provides
an important test of the Standard Model of electroweak interactions.
Arrival of the final proofs: 28 November 2005
This paper is dedicated to the memory of Steve O'Neale 相似文献
19.
We calculate the contribution of semi-hadronic states with the pseudoscalar P = π0, η and scalar (σ(550)) meson accompanied with a real photon as an intermediate state of a heavy photon to the anomalous magnetic
moment of the muon. We consider the intermediate states with π0 and σ as hadrons in the frame-work of the Nambu-Jona-Lasinio (NJL) model. The contribution of the π0γ state is in agreement with results obtained in previous theoretical considerations as well as with the experimental data
$
a_\mu ^{\pi _0 \gamma } \approx 4.5 \times 10^{ - 10}
$
a_\mu ^{\pi _0 \gamma } \approx 4.5 \times 10^{ - 10}
, besides we estimate a
μηγ = 0.7 × 10−10, a
μσγ ∼ 1.5 × 10−11, $
a_\mu ^{\pi ^ + \pi ^ - \gamma } \sim 3.2 \times 10^{ - 10}
$
a_\mu ^{\pi ^ + \pi ^ - \gamma } \sim 3.2 \times 10^{ - 10}
. We also discuss the light-by-light (LbL) mechanism with a
μ
lbl
= 10.5 × 10−10. 相似文献
20.
Yu. M. Andreev S. I. Bityukov N. V. Krasnikov A. N. Toropin 《Physics of Atomic Nuclei》2007,70(10):1717-1724
The LHC (CMS) discovery potential in the search for supersymmetry and lepton-flavor violation in neutralino decays using the
e
± μ∓ + E
T
miss
signature is studied. A detailed study is done for the CMS test points LM1-LM9. It is shown that, for the point LM1, it is
possible to detect lepton-flavor violation in neutralino decays with lepton-flavor-violating branching Br(
→ μ±
e
∓
) ≥ 0.04 Br(
→ e
+
e
−
, μ+ μ−
) for an integral luminosity of 10 fb−1. The discovery potential in the mSUGRA-SUSY scenario with tan β = 10, sgn(μ) = + in the (m
0, m
1/2) plane using the e
± μ∓ + E
T
miss
signature is determined.
The text was submitted by the authors in English. 相似文献