共查询到20条相似文献,搜索用时 15 毫秒
1.
We show that instanton effects may play an important role in the decay of scalar mesons into two pseudoscalars. Particularly the branching ratios of two meson decays of the f0(1500), which is considered as a glue-ball candidate, are compatible with an ordinary q
-structure of this resonance and a small positive SU(3) mixing angle, in agreement with a result from a recent calculation of the spectrum with the same instanton-induced force. Predictions for the a0(1450)-branching ratios are made. 相似文献
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J.L. Richard 《Physics letters. [Part B]》1982,115(2):134-136
The instanton contribution for the CP1 model with periodic boundary conditions is interpreted as the partition function of a neutral Coulomb gas in a finite volume. 相似文献
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We show that nucleon pole terms contribute significantly to proton decay, increasing the branching ratio for e+π0 and modes. The total lifetime is decreased to the point where keeping the SU(5) value of the lifetime below the experimental upper bound forces us to the choice of QCD scale parameter and proton radius parameter which are near the edge of the allowed region. 相似文献
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Yu. V. Gaponov 《Physics of Atomic Nuclei》2000,63(7):1200-1205
A possible mechanism of the virtual intermediate-scalar-leptoquark-boson exchange associated with the contribution of right-handed nucleon currents to free-neutron beta decay is demonstrated. The hypothesis can be extended by considering the realization of the same mechanism in beta decay via the emission of right-handed neutrinos (left-handed antineutrinos). It is shown that a hypothesis of this kind leads to the appearance of scalar and tensor terms in the effective Hamiltonian of weak interaction and that these terms include the right-handed neutrinos. Relevant experimental data are discussed. 相似文献
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S. G. Kadmensky 《Physics of Atomic Nuclei》2004,67(12):2134-2138
By using the formalism of the quantum theory of fission, the amplitudes of partial decay widths and the asymptotic behavior of the wave function for a decaying nucleus are found with allowance for open-decay-channel coupling not only for fission, but also for the binary decays of nuclei through protonic, alphaparticle, cluster, and other channels. 相似文献
9.
Y.-B. Zhang H.J.W. Müller-Kirsten 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):351-363
An instanton method is proposed to investigate the quantum tunneling between two weakly-linked Bose-Einstein condensates confined
in double-well potential traps. We point out some intrinsic pathologies in the earlier treatments of other authors and make
an effort to go beyond these very simple zero order models. The tunneling amplitude may be calculated in the Thomas-Fermi
approximation and beyond it; we find it depends on the number of the trapped atoms, through the chemical potential. Some suggestions
are given for the observation of the Josephson oscillation and the MQST.
Received 29 June 2001 and Received in final form 17 September 2001 相似文献
10.
D. V. Soa P. V. Dong T. T. Huong H. N. Long 《Journal of Experimental and Theoretical Physics》2009,108(5):757-763
A new bound of the mixing angle between charged gauge bosons (the standard-model W and the bilepton Y) in the economical 3-3-1 model is given. Possible contributions of the charged bileptons to the neutrinoless double beta
((ββ)0ν) decay are discussed. We show that the (ββ)0ν decay in this model is due to both the Majorana 〈M
ν〉
L
and Dirac 〈M
ν
〉D neutrino masses. If the mixing angle is in the range of the ratio of neutrino masses 〈M
ν
〉
L
/〈M
ν
〉D, the Majorana and Dirac masses are comparable to each other and both may give the main contribution to the decay. As a result,
constraints on the bilepton mass are given.
The article is published in the original. 相似文献
11.
《Nuclear Physics B》1986,274(2):475-508
The vacuum of N = 1 quantum mechanics is shown to be the dilute gas of instanton-anti-instanton molecules with zero topological charge. The quantum fluctuations near these molecules are nontrivial due to the quasizero mode. The special technique of integration along this mode in the functional space beyond the gaussian approximation is worked out. We also discuss nonsupersymmetric quantum mechanics with fermions and calculate the nonperturbative part of the corresponding vacuum energy. 相似文献
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G. N. Abelyashev V. N. Berzhanskii A. I. Gorbovanov S. N. Polulyakh N. A. Sergeev 《Journal of Experimental and Theoretical Physics》1999,89(1):112-118
We analyze the influence of fluctuations of the nonsecular part of the spin Hamiltonian on the decay of ordinary and multiquantum
signals of the two-pulse spin echo in a quadrupole spin system with an inhomogeneously broadened spectral line. Expressions
are obtained for the rate of decay of an echo in the case of selective excitation of a signal from quadrupole nuclei with
arbitrary spin. These expressions are then used to analyze the experimentally observed ordinary and multiquantum echo signals
from quadrupole nuclei with spin I=3/2 (53Cr, 63Cu, and 65Cu) in ferromagnetic chromium chalcogenide spinels.
Zh. éksp. Teor. Fiz. 116, 204–216 (July 1999) 相似文献
15.
H. V. Klapdor-Kleingrothaus Spokesman HEIDELBERG-MOSCOW GENIUS Collaborations 《Nuclear Physics B - Proceedings Supplements》2001,100(1-3)
Double beta decay is indispensable to solve the question of the neutrino mass matrix together with ν oscillation experiments. The most sensitive experiment - since eight years the HEIDELBERG-MOSCOW experiment in Gran-Sasso - already now, with the experimental limit of mν < 0.26 eV practically excludes degenerate ν mass scenarios allowing neutrinos as hot dark matter in the universe for the smallangle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond SM physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments. 相似文献
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The non-unique first-forbidden 1?(1.9 MeVβ ?)2+ transition in the decay of148Pm is studied. The nuclear matrix elements are evaluated using for the ground state of the odd-odd148Pm a phenomenological wave function derived in a previous work in the framework of the two-quasiparticle model and assuming that the first excited 2+ state in148Sm can be described as the first quadrupole phonon state. This model provides nuclear matrix elements which are capable of describing experimental data like the spectrum shape factor, the longitudinal polarization of the electrons and a particular set ofβ-γ directional correlation coefficients, but it fails to interpret the large logft value of this transition. In addition, the validity of theξ-approximation is discussed. 相似文献
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S.M.H. Wong 《The European Physical Journal C - Particles and Fields》2000,14(4):643-671
In the last years, the need for the color octet state in inclusive P-wave charmonium decay has been firmly established. However,
the implications of this in the corresponding exclusive reactions have not been fully recognized. We argue for the necessity
of the color octet in P- and higher-wave quarkonium decay. Using a set of phenomenologically constructed baryon wave functions,
we consider the decay into an octet and decuplet baryon–antibaryon pair. By doing so, we subject the wave functions to a test of applicability.
We show that the color singlet component alone is insufficient to account for the experimental measurements, and only by including
the color octet contribution can the partial theoretical decay widths be brought into the range of the data. By the present
and earlier applications of the set of wave functions, these show themselves to be reasonable model wave functions at around
the scale –20 GeV.
Received: 1 March 1999 / Published online: 18 May 2000 相似文献