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1.
Weak transitions of decuplet isobars are expanded in terms of eigen-amplitudes of the direct channel in the framework of SU(3).
Starting with the most general weak Hamiltonian and assuming intermediate states to be non-exotic, we obtain ΔI=1/2 rule for Ω− decays. Invoking of the CP invariance forbids all thepv weak processesD(10)→D(10) +P(8). Decays of the charmed multiplets are also discussed in these dynamical considerations. We obtain triplet dominance of
charm changing weak Hamiltonian for Ω*++
3 decays. 相似文献
2.
Configuration assignments are derived for the observed energy levels in the odd-odd deformed nucleus170Lu99 based on the calculations of the two-particle band head energies for a zero range residual interaction, the beta-feeding
characteristics, and the observed features for similar bands in the neighbouring nuclei. In particular, specific assignments
are given for theJ
π
=1+ levels at 198.4 keV, 349.0 keV and 785.5 keV. The ambiguities with respect to the assignments for theK
π=3− bands are discussed. A new isomer withJ
π
=7+ and half-life of several seconds is predicted around (225±25) keV and experiments are suggested to identify it. 相似文献
3.
K. Azizi 《The European Physical Journal C - Particles and Fields》2009,61(2):311-319
Due to the very short life time of the Δ baryons, a direct measurement on the electromagnetic moments of these systems is almost impossible in the experiment and
can only be done indirectly. Although only for the magnetic dipole moments of Δ
++ and Δ
+ systems there are some experimental data, the theoretical, phenomenological and lattice calculations could play crucial role.
In the present work, the magnetic dipole (μ
Δ
), electric quadrupole (Q
Δ
) and magnetic octupole (O
Δ
) moments of these baryons are computed within the light cone QCD sum rules. The results are compared with the predictions
of the other phenomenological approaches, lattice QCD and existing experimental data. 相似文献
4.
J.Y. Huh C.S. Lee Y.K. Kwon J.Y. Kim Y. Gono T. Morikawa H. Watanabe M. Shibata S. Motomura T. Tsutsumi T. Fukuchi T. Kishida E. Ideguchi X.H. Zhou A. Odahara S. Kubono J.H. Ha M.K. Cheoun C. Lee J.C. Kim C.-B. Moon S.J. Chae Y.K. Kim J.S. Chai 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):11-14
High-spin states of 155Gd were populated by using the 154Sm(α,3nγ)155Gd reaction at E
α= 33 MeV. γ-γ coincidence, E
γ singles, excitation function, and the DCO ratios were measured. we have identified three intermediate bands with ΔI= 2 feeding the positive yrast band. The bands are interpreted as such candidate bands that are mixed with the negative-parity
ground state band. This observation can provide a plausible explanation for unusually large population of the positive-parity
yrast band observed in a recent Coulomb excitation.
Received: 2 November 1999 相似文献
5.
In this study quasiparticle random-phase approximation with the translational invariant Hamiltonian using deformed mean field
potential has been conducted to describe electric dipole excitations in 136Xe, 138Ba, 140Ce, 142Nd, 144Sm and 146Gd isotones. The distribution of the calculated E1 strength shows a resonance like structure at energies between 6–8 MeV exhausting up to 1% of the isovector electric dipole
Energy Weighted Sum Rule and in some aspects nicely confirms the experimental data. It has been shown that the main part of
E1 strength, observed below the threshold in these nuclei may be interpreted as main fragments of the Pygmy Dipole resonance.
The agreement between calculated mean excitation energies as well as summed B(E1) value of the 1− excitations and the available experimental data is quite good. The calculations indicate the presence of a few prominent
positive parity 1+ States in heavy N = 82 isotones in the energy interval 6–8 MeV which shows not all dipole excitations were of electric character in this energy
range. 相似文献
6.
F. Reinert P. Steiner Th. Engel S. Hüfner 《Zeitschrift für Physik B Condensed Matter》1995,99(1):223-227
Electron-energy loss spectra of potassium permanganate (KMnO4) with primary electron energies 25 eV<=E0<=500 eV show 7 peaks in the energy-loss range 1 eV<=ΔE<=10eV and are successfully analysed with a superposition of 7 independent
Gaussians. The intensity of these lines follow roughly a power-law dependence on the primary energy I∝E
0
-α
. There are two groups of lines, the first with an exponent α≈0.5, while the lines in the second group decay much stronger
with increasingE
0 corresponding to a value 0.9<=α<=1.3. The 4 lines in the first group are identified as dipole allowed transitions by comparison
to recent first principle molecular-orbital calculations for the (MnO4) molecule by H. Nakai et al. The dipole-allowed excitation spectrum obtained from this analysis agrees very well with these
first principle calculations. 相似文献
7.
Some of the low-lying states in many isotopes144Nd,148Sm,152Gd and156Gd show a similar typical behaviour. The first 2+ is regarded as a single quadrupole phonon state and 3− as a single octupole phonon state. The levels with the spins and parities 1−, 5−, 3−, 4−, etc. are considered due to the simultaneous excitation of quadrupole and octupole phonons. If this consideration is correct,
then the transition fromJ
− to 2+ states must contain an appreciableE3 content. Theβ-γ-γ angular correlation coefficients for the cascade ofβ-rays ofE
max 800 keV→γ-rays of 1489 keV→γ-rays of 696 keV are used to estimateE3 content inE1 transition in144Nd. 相似文献
8.
Wang Zhi-wen Han Qiu-ju Hu Mu-hong Yang Di Li Jin-ying 《Frontiers of Physics in China》2006,1(1):102-107
The ionization potentials and fine structure splittings of 1s2
nl (l = s, p, and d; n ⩽ 9) states for lithium-like V20+ ion are calculated by using the full-core plus correlation (FCPC) method. The quantum defects of these three Rydberg series
are determined according to the single-channel quantum defect theory (QDT). The energies of any highly excited states with
n ⩾ 10 for these series can be reliably predicted using the quantum defects that are function of energy. The dipole oscillator
strengths for the 1s22s–1s2
np and 1s22p–1s2
nd (n ⩽ 9) transitions of V20+ ion are calculated with the energies and FCPC wave functions obtained above. Combining the QDT with the discrete oscillator
strengths, the discrete oscillator strengths for the transitions from the given initial state to highly excited states (n ⩾ 10) and the oscillator strength density corresponding to the bound-free transitions are obtained.
Translated from Chinese Journal of Atomic and Molecular Physics, 2005(2) (in Chinese) 相似文献
9.
A many-body microscopic band-mixing formulation of variation after projection of angular momentum and conservation of nucleon
number is used to study the yrast band and first excitedK
π
=0+ band in the doubly even nuclei154,156Gd. The computed energy spectra and the interband and intra-band B (E2) values are in good agreement with corresponding experimental
data. Connection with the phenomenological model of Stephens and Simon is discussed, bringing out the role played by thei
13/2 neutron pair in the microscopic formalism. 相似文献
10.
E. O. Lieder A. A. Pasternak R. M. Lieder A. D. Efimov V. M. Mikhajlov B. G. Carlsson I. Ragnarsson W. Gast Ts. Venkova T. Morek S. Chmel G. de Angelis D. R. Napoli A. Gadea D. Bazzacco R. Menegazzo S. Lunardi W. Urban Ch. Droste T. Rzaca-Urban G. Duchêne A. Dewald 《The European Physical Journal A - Hadrons and Nuclei》2008,35(2):135-158
For a level scheme investigation of 142Gd an experiment with the γ -spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL
IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the
99Ru(48Ti, 2p3n) reaction at a beam energy of 240MeV and the 114Sn(32S, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole
bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former
calculations it was concluded that the high-spin states of the (+ , 0)1 band in 142Gd represent a triaxial nucleus rotating around the longest principal axis. 相似文献
11.
The formation of deeply-bound antikaonic nuclear states in nuclear (K−,N) reactions is investigated theoretically within a distorted-wave impulse approximation (DWIA), considering the isospin properties of the Fermi-averaged elementary amplitudes. We calculate the formation cross sections of the deeply-bound states by the (K−,N) reactions on the nuclear targets, 12C and 28Si, at incident K− lab momentum pK−=1.0 GeV/c and θlab=0°, introducing a complex effective nucleon number Neff for unstable bound states in the DWIA. The results show that the deeply-bound states can be populated dominantly by the (K−,n) reaction via the total isoscalar ΔT=0 transition owing to the isospin nature of the amplitudes, and that the cross sections described by ReNeff and ArgNeff enable to deduce the structure of the nuclear states; the calculated inclusive nucleon spectra for a deep -nucleus potential do not show distinct peak structure in the bound region. The few-body and states formed in (K−,N) reactions on s-shell nuclear targets, 3He, 3H and 4He, are also discussed. 相似文献
12.
E. Guliyev A. A. Kuliev F. Ertugral 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):323-333
In this study the QRPA approach with the rotational and translational invariant Hamiltonians has been carried out to describe
magnetic and electric dipole excitations in 176Hf . Calculations show that the 176Hf nucleus demonstrates a very rich B(M1) strength structure and in some aspects nicely confirm the experimental data. It has been shown that the main part of spin-1
states, observed at 2-4MeV in 176Hf , may be attributed to have a M1 character and may be interpreted as the main fragments of the scissors mode. The agreement between the calculated mean excitation
energies as well as the summed B(M1) values of the scissors mode excitations and the available experimental data is quite good. The constructive interference
between the orbit and the spin part of M1 strength has been found to be below 3.5MeV. The calculations indicate the presence of a few prominent negative-parity states in the 2-4MeV energy interval. This suggests that the supposition of the experiment “all stronger
K = 1 low-lying dipole excitations were of magnetic character” cannot be generalized. 相似文献
13.
D P Ahalpara 《Pramana》1979,12(2):179-201
The low-lying collective bands of positive parity states in (fp) shell nuclei are described in the deformed Hartree-Fock method by projecting states of definite angular momenta from ‘the
lowest energy intrinsic states in (sd)−1 (fp)
n+1 configurations. The modified Kuo-Brown effective interaction for (fp) shell and modified surface delta interaction (MSDI) for a hole in (sd) shell with a particle in (fp) shell have been used.
The collective bands of states are in general well reproduced by the effective interactions. The excitation energies of the
band head states are however off by about one MeV. The calculated magnetic moments of the band headj=3/2+ states are in reasonable agreement with experiment. Using effective chargese
p=1.33e ande
n=0.64e we get fairly good agreement forE(2) transitions. The hinderedM(1) transition strengths are reproduced to the correct order however they are slightly higher compared to experiment. 相似文献
14.
The adiabatic potential energy, the spectroscopic constants and the transition dipole moments of the lowest electronic states of the LiK+ molecule, dissociating into Li(2s, 2p, 3s, 3p, 3d, 4s, and 4p) + K+ and Li+ + K(4s, 4p, 5s, 3d, 5p, 4d, and 6s), have been investigated. We have used an ab initio approach involving a non-empirical pseudopotential for the Li (1s2) and K (1s22s22p63s23p6) cores and core valence correlation correction. A very good agreement has been obtained for the ground state for the spectroscopic constants with the available theoretical works. The transition dipole moment from X2Σ, 22Σ, 32Σ, and 42Σ states to higher excited states have been determined. Numerous avoided crossing between electronic states of 2Σ and 2Π symmetries, have been localised and analysed. Their existences are related to the charge transfer process between the two ionic systems Li+K and LiK+. 相似文献
15.
The mechanism of 1:1 dipolar complexation of some long-chain aliphatic alcohols with chlorobenzene and acetic acids in a non-polar
medium is studied. The interaction dipole moment △→μ, the excess molar polarization ΔP and apparent complex formation constantK
app are evaluated following two independent methods. It is observed from the value of △→μ that the complex formation is mostly due to polarization interaction and is of the same type as involving lower alcohols.
ΔP andK
app are, however, of different nature compared to those in lower alcohols suggesting that the unlike molecules form relatively
stable linear linkage resulting in antiparallel orientation prior to forming complexes. 相似文献
16.
The transition energies, wavelengths and dipole oscillator strengths of 1s22p—1s2
nd (3⩽n⩽9) for Mn22+ ion are calculated. The fine structure splittings of 1s2
nd (n</9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated
under a hydrogenic approximation. The quantum defect of Rydberg series 1s2
nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experimental
data available in literatures.
Supported by the National Natural Science Foundation of China (Grant No. 10774063) 相似文献
17.
T. Shizuma T. Ishii H. Makii T. Hayakawa S. Shigematsu M. Matsuda E. Ideguchi Y. Zheng M. Liu T. Morikawa P. M. Walker M. Oi 《The European Physical Journal A - Hadrons and Nuclei》2006,30(2):391-396
Excited states in neutron-rich 188W have been populated using a 186W(18O,16O) reaction. In-beam γ-rays were measured in coincidence with scattered particles detected by a high-resolution ΔE-E Si telescope. In this experiment, the ground-state band has been identified up to I
π = 8+. The γ band, the K
π = 2- octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent
HFB cranking calculations and blocked-BCS multi-quasiparticle calculations. 相似文献
18.
Two kinds of general consequences of the ΔS=0 weak hadron neutral current independent of a gauge model are presented. Firstly are results which depend on the quark parton
model. These involve bounds among neutrino inclusive cross-section and a bound onQ(Z, N) in terms of these inclusive cross-sections. Secondly are results which are independent of the quark-parton model and depend
only on the SU(3) structure of the most general ΔS=0 neutral current. These tests of isopin and speciallyU-spin properties of the current are given forv+N→v+hadron+anything,v+N→v+baryon+meson ande
+
e
−→baryon+anti-baryon. In addition some conjectures are made with regard to the semi-inclusive neutrino-reactions using the
quark parton model. 相似文献
19.
Configuration interaction calculations have been carried out on electronic states of the CsLi molecule and the CsLi+ cation. Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels are presented for the
lowest states of 1,3Σ+, 1,3Π, and 1,3Δ symmetries of the alkali dimer CsLi molecule dissociating into Cs (6s, 6p, 5d, 7s, and 7p) + Li (2s, 2p, 3s, 3p, and 3d)
as well as for the lowest 2Σ+, 2Π, and 2Δ electronic states of the CsLi+ cation dissociating into Li (2s, 2p, 3s, 3p, and 3d) + Cs+ and Li+ + Cs (6s, 6p, 5d, 7s, and 7p). The results of the present many-electron configuration interaction calculations on the cation
support the previous core-polarization effective potential calculations. The present calculations on the CsLi molecule are
complementary to previous theoretical work on this system, including recently observed electronic states that had not been
calculated previously. We have used an ab initio approach involving a nonempirical pseudopotential for the Li (1s2) and Cs cores and a core-valence correlation correction. A very good agreement of data from spectroscopic constants for some
of the lowest states of the CsLi and CsLi+ molecules with those available in recent theoretical works has been obtained. The existence of numerous avoided crossings
between electronic states of 2Σ+ and 2Π symmetries is related to a charge transfer process between the two ionic CsLi+ and LiCs+ systems. 相似文献
20.
Z. Rudy W. Cassing L. Jarczyk B. Kamys P. Kulessa 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):303-314
The production of K+-mesons in proton-nucleus collisions from 1.0 to 2.5GeV is analyzed with respect to one-step nucleon-nucleon ( NN → NYK
+) and two-step Δ-nucleon ( ΔN → K
+
YN) or pion-nucleon ( πN → K
+
Y) production channels on the basis of a coupled-channel transport approach (CBUU) including the kaon final-state interactions.
The influence of momentum-dependent potentials for the nucleon, hyperon and kaon in the final state are studied as well as
the importance of K+ elastic rescattering in the target nucleus. The transport calculations are compared to the experimental K+ spectra taken at LBL Berkeley, SATURNE, CELSIUS, GSI and COSY-Jülich. It is found that the momentum-dependent baryon potentials
affect the excitation function of the K+ cross-section; at low bombarding energies of ∼ 1.0GeV the attractive baryon potentials in the final state lead to a relative
enhancement of the kaon yield, whereas the net repulsive potential at bombarding energies ∼ 2GeV causes a decrease of the
K+ cross-section. Furthermore, it is pointed out that especially the K+ spectra at low momenta (or kinetic energy T
K) allow to determine the in-medium K+ potential almost model independently due to a relative shift of the K+ spectra in kinetic energy that arises from the acceleration of the kaons when propagating out of the nuclear medium to free
space, i.e. converting the potential energy to the kinetic energy of the free kaon.
Received: 28 January 2002 / Accepted: 3 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: Wolfgang.Cassing@theo.physik.uni-giessen.de
Communicated by P. Schuck 相似文献