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1.
G. Puddu 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):171-181
We extend the recently presented formalism for Monte Carlo calculations of the partition function, for both even and odd particle
number systems (Phys. Rev. C 59, 2500 (1999)), to the calculation of many-body matrix elements of the type <ψ| e
- βℋ|ψ> where |ψ> is a many-body state with a definite angular momentum, parity, neutron and proton numbers. For large β such
matrix elements are dominated by the lowest eigenstate of the many-body Hamiltonian ℋ, corresponding with a given angular
momentum parity and particle number. Emphasis is placed on odd-mass nuclei. Negligible sign fluctuations in the Monte Carlo
calculation are found provided the neutron and proton chemical potentials are properly adjusted. The formalism is applied
to the J
π = 0+ state in 166
Er and to the J
π = 9/2-, 13/2+, 5/2- states in 165
Er using the pairing-plus-quadrupole model.
Received: 28 April 2000 / Accepted: 20 September 2000 相似文献
2.
I.V. Anikin B. Pire L. Szymanowski O.V. Teryaev S. Wallon 《The European Physical Journal C - Particles and Fields》2006,47(1):71-79
We present a theoretical study of exotic hybrid meson (JPC=1- +) production in photon-photon collisions where one of the photons is deeply virtual, including twist two and twist three contributions.
We calculate the cross section of this process, which turns out to be large enough to imply sizeable counting rates in the
present high luminosity electron–positron colliders. We emphasize the importance of the πη decay channel for the detection
of the hybrid meson candidate π1(1400) and calculate the cross section and the angular distribution for π η pair production in the unpolarized case. This
angular distribution is a useful tool for disentangling the hybrid meson signal from the background. Finally, we calculate
the single spin asymmetry associated with one initial longitudinally polarized lepton. 相似文献
3.
J?rg Hennig Carla Cederbaum Marcus Ansorg 《Communications in Mathematical Physics》2010,293(2):449-467
We prove that in Einstein-Maxwell theory the inequality (8π
J )2+(4π
Q
2)2 < A
2 holds for any sub-extremal axisymmetric and stationary black hole with arbitrary surrounding matter. Here J, Q, and A are angular momentum, electric charge, and horizon area of the black hole, respectively. 相似文献
4.
The three-dimensional cranked Hartree-Fock-Bogoliubov calculation was carried out in 182Os for the states with angular momenta J = 16ℏ -30ℏ . It is proposed that a family of states of tilted axis rotation forms a band which is expected to be the t -band with K = 8 . 相似文献
5.
G. K. Ivanov G. V. Golubkov S. V. Drygin I. E. Cherlina 《Journal of Experimental and Theoretical Physics》1997,84(5):888-892
Ionization and dissociation of diatomic molecules induced by a weak field (after preliminarily populating an intermediate
level) and by intense, linearly polarized monochromatic radiation have been studied. Field-induced mixing of rotational components
of various electronic-vibrational states of molecules (such as CO, NO, etc.) at field strength f∼10−4–10−5 atomic units can lead to migration among states with different angular momenta J. Therefore, ions with rotational momenta J
+ much higher than those prescribed by selection rules for three-photon absorption can be formed from molecules in the ground
state. The possibility of selective formation of ions with J
+≫1 and zero projection of the angular momentum on the polarization vector of the external electromagnetic radiation has been
investigated.
Zh. éksp. Teor. Fiz. 111, 1624–1632 (May 1997) 相似文献
6.
E. V. Rosenfeld 《Journal of Experimental and Theoretical Physics》2010,111(3):440-449
The appearance and development of aperiodic distortions in a helicoidal, layered magnetic structure with increasing crystallographic
magnetic anisotropy in the magnetization rotation plane have been theoretically studied. A simple phase diagram for this system
is proposed. It is established that, at a weak anisotropy, the spiral splits into regions of various lengths with an approximately
uniform rotation of the magnetization in each region and a deviation from uniformity at the boundaries; the stronger the anisotropy,
the shorter the regions and the greater the deviations. In the limit of high anisotropy, the minimum energy of the system
corresponds (depending on the ratio of interlayer exchange integrals J
1 and J
2) to either a spiral with constant angular pitch (a multiple of the angle between easy axes) or a double antiferromagnetic
structure with a four-layer period. In the case of sixth-order anisotropy with |J
1| = −J
2, the energies of phases with different periods (four and six layers for J
1 > 0; four and three layers for J
1 < 0) coincide and the excess boundary energy vanishes. In the case of a fourth- and second-order anisotropy, the analogous
anomalies appear at |J
1| = −2J
2. As a result, the magnetic structure at these points becomes unstable and the phase diagram exhibits the corresponding singularities. 相似文献
7.
Spectrally resolved laser-induced fluorescence technique was used to uniquely assign total angular momentum (J) values to high-lying even-parity energy levels of atomic samarium. Unique J value assignment was done for seven energy levels in the energy region 34,800–36,200 cm−1, recently observed and reported in the literature. 相似文献
8.
Sh. A. Ehgamberdiev 《Radiophysics and Quantum Electronics》1996,39(10):817-819
This paper is devoted to the measurement of low-degree p mode rotational splitting, which is one of the most urgent problems in helioseismology. The last three years witnessed considerable progress in this field. It can be stated with confidence that the angular velocity of solar core rotation exceeds only marginally or even does not exceed the rotation velocity of the Sun envelope, except for an area of radius 0.1R
in the deep interior of the core. Further progress in this avenue encounters a variety of serious difficulties for lack of reliable data on g modes. These difficulties are due to the physical nature of the p modes themselves and the imperfection of the analytical techniques.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 10, pp. 1218–1221, October, 1996. 相似文献
9.
The critical current J
c(θ) of an intergrain boundary is calculated as a function of the contact misorientation angle θ of the granules. It is assumed that the ordering parameter is suppressed in regions near boundaries with an enhanced mechanical
stress induced by randomly distributed surface dislocations. The stress distribution function is determined using a probabilistic
approach. Assuming that the weak coupling at the boundary is Josephson coupling, an analytic expression is found for the angular
dependence J
c(θ) (for tilt and twist boundaries). The magnitude of the residual critical current of a boundary in a strong magnetic field
is estimated.
Fiz. Tverd. Tela (St. Petersburg) 40, 393–402 (March 1998) 相似文献
10.
W.-D. Zeitz S. Unterricker F. Schneider V. Samokhvalov K. Potzger A. Weber M. Dietrich 《Hyperfine Interactions》2004,158(1-4):437-441
The magnetic response of europium in γ-cerium and in platinum was studied by applying the perturbed angular correlation spectroscopy.
The probe nuclei were 147Eu(11/2−) and 149Eu(11/2−). The response in γ-Ce was determined by the electronic S = J = 7/2 ground state of divalent Eu. In Pt, on the other hand, Eu is trivalent (J = 0 ground state). Here the magnetic contributions originate from Van Vleck terms of the whole multiplet system. 相似文献
11.
M. Oinonen U. Köster J. Äystö V. Fedoseyev V. Mishin J. Huikari A. Jokinen A. Nieminen K. Peräjärvi A. Knipper G. Walter 《The European Physical Journal A - Hadrons and Nuclei》2001,10(2):123-127
Beta-decay of 59Mn has been studied at PSB-ISOLDE, CERN. The intense and pure Mn beam was produced using the Resonance Ionization Laser Ion
Source (RILIS). Based on the measured β-decay rates the ground-state spin and parity are proposed to be J
π = 5/2-. This result is consistent with the systematic trend of the odd-A Mn nuclei and extends the systematics one step further towards the neutron drip line.
Received: 17 November 2000 / Accepted: 16 February 2001 相似文献
12.
T. Sumikama T. Iwakoshi T. Nagatomo M. Ogura Y. Nakashima H. Fujiwara K. Matsuta T. Minamisono M. Mihara M. Fukuda K. Minamisono T. Yamaguchi 《Hyperfine Interactions》2004,159(1-4):281-284
The pure nuclear spin alignments of 8Li and 8B were produced from the nuclear spin polarization applying the β-NMR method. The alignment correlation terms in the β-ray angular distribution were observed to test the G parity conservation in the nuclear β decay. 相似文献
13.
E. Ya. Paryev 《Physics of Atomic Nuclei》2006,69(4):721-733
Within the spectator model, we study the reaction γd → K
−Θ+
p → K
−
K
+
np in the threshold energy region. We present the predictions for the exclusive and inclusive K
−-meson angular distributions in the laboratory system for this reaction calculated for two possible parity states of the Θ+ resonance at 1.5-and 1.75-GeV beam energies with and without imposing the relevant kinematical cuts on those parts of the
sampled phase space where the contribution from the main background sources, associated with the ϕ(1020), Λ(1520) production
as well as with the K
−
p rescattering in the final state, is expected to be dominant. We show that, under the chosen kinematics, these distributions
are sensitive to the Θ+ parity and, therefore, can be used as a filter for the determination of its parity.
The text was submitted by the author in English. 相似文献
14.
K.-M. Källman M. Brenner V.Z. Goldberg T. Lönnroth P. Manngård A.E. Pakhomov V.V. Pankratov 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):159-169
The excitation function and angular distributions of elastic α-particle scattering on 28Si have been measured in the laboratory energy range 6-28 MeV using a backscattering technique on a thick target, yielding
a continuous energy distribution. More than 200 narrow states are observed, with widths in the range ∼ 30-100 keV at excitation
energies E
* = 13-32 MeV. Angular distributions at backward angles were measured, and angular momentum values of more than 83 states have
been deduced. The analysis gives spin-parities J
π, α-partial widths Γα and reduced widths of the narrow high-lying resonant states in 32S. The experimentally observed states display both the negative- and the positive-parity rotational-like sequences with seemingly
no parity splitting, a finding which is at variance with most potential-model predictions. The deduced effective moment of
inertia indicates a more extended structure than the ground-state configuration. The observed strength of each ℓ-value is
analyzed in terms of an underlying split doorway state of Lorentzian form, which yields an interpretation as fragmented rotational
α + 28Si states.
Received: 26 June 2000 / Accepted: 16 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: kkallman@abo.fi
RID="b"
ID="b"Present address: Swedish Polytechnic, FIN-65200 Vasa, Finland.
Communicated by D. Guerreau 相似文献
15.
We investigate the spin-3/2 baryons in the 27-plet based on flavor SU(3) symmetry. For J
p = 3/2+, we find all the candidates for non-exotic members. For J
p = 3/2-, we predict a new non-exotic member Λ(1780). Fitting the mass spectrum and calculating the widths of the members show an
approximate symmetry of the 27-plet of SU(3). We find that the exotic members have relatively large widths and the Ξ(1950) has spin and parity J
p = 3/2-. The possibility of assigning the non-exotic candidates to an octet is also analyzed. 相似文献
16.
S. S. Aplesnin 《Physics of the Solid State》1998,40(6):986-990
An analysis is made of the two-dimensional Heisenberg model with S=1/2, anisotropic exchange interaction between nearest neighbors, and alternating exchange in two directions, [100] and [010]
(corresponding to condensation of the (π, π) mode) and in one direction [100] (corresponding to condensation of the (π, 0) mode). The quantum Monte Carlo method is used to calculate the thermodynamic characteristics and the spin correlation
functions which are used as the basis to determine the boundary of stability of an anisotropic antiferromagnetic with respect
to alternation of exchange δ=(1−J
x,y
/J
z
)0.4 in the (π,π) model and δ=(1−J
x,y
/J
z
)0.31 in the (π,0) model. In the (π,0) model a disordered quantum state exists in the range (1−J
x,y
/J
z
)0.31<δ<(0.3–0.35). The energy (E−0.68)=0.36δ
1.80(6) and 0.21 δ
2.0(5), the energy gap between the ground and excited states H
c
(δ)=1.96δ
2.(1), 1.8(1) (δ−0.35(3))0.67(2) were determined as a function of the alternation of exchange in the (π,π)-and (π,0) models, respectively.
Fiz. Tverd. Tela (St. Petersburg) 40, 1080–1085 (June 1998) 相似文献
17.
G.D. Jones P.A. Butler T.H. Hoare P.M. Jones 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):129-141
The low spin states of 223Ra have been populated via α-decay from 227Th which was itself produced following β− decay of an 227Ac source. α–γ and α−e
K,L,M angular correlation measurements have been analysed using the correct ground state spins of 227Th(=1/2+) and 223Ra(=3/2+) for the first time.
The analysis has allowed unique Jπ values to be assigned to almost all levels below 400 keV excitation in 223Ra.
Values of (g
K−g
R)/Q
0 have been deduced for several members of the K= 3/2± bands (for the first time in an odd N nucleus in this mass region) allowing estimates of g
K and g
R to be extracted. The values of g
K and g
R are not significantly different for the positive and negative parity band members and tend to support other strong evidence
that stable octupole deformation exists in 223Ra at low excitation energies.
Received: 17 November 1997 / Revised version: 8 January 1998 相似文献
18.
We present new theoretical calculations of nuclear fusion rates λ
f
J
from the resonant states of the muonic molecular ion 3Hedμ
++ with total angular momenta J=0,1. As a byproduct, new very accurate variational wave functions for these states have been obtained. Using these wave functions,
the probability density |Ψ(R=0)|2 in a fusion region has been calculated by extrapolating the variational solution to small internuclear distances by means
of the multi-channel adiabatic solution. Calculated fusion rates for the states J=0 and J=1 are: λ
f
0
=1.9·105s-1 and λ
f
1
=0.65·103s-1, respectively.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
A.W.K. Mok K.J. Sebastian 《The European Physical Journal C - Particles and Fields》2008,56(2):189-202
Using the helicity formulism, we calculate the combined angular distribution function of the polarized gamma photons and electron
in the cascade process pp̄→ψ’→χJ+γ1→ψ+γ2+γ1→e++e-+γ2+γ1 (J=0,1,2), when p̄ and p are unpolarized. We also present the partially integrated angular distribution functions in different
cases. Our results show that by measuring the two-particle angular distribution of γ1 and γ2 and that of γ2 and e- with the polarization of either one of the two particles, one can determine the relative magnitudes as well as the relative
phases of the helicity amplitudes in the radiative decay processes ψ’→χJ+γ1 and χJ→ψ+γ2.
PACS 11.80.Cr; 13.20.Fc; 13.60.Le; 14.40.Gx 相似文献
20.
The angular dependences of the electron spin resonance spectrum of 1% Ni2+ ions in a ZnSiF6·6H2O matrix are investigated experimentally at 36 GHz and 4.2 K. Besides the main spectrum of the isolated ion, we observed a
spectrum due to interacting pairs of Ni2+ ions, located in the first (nn) and second (2n) coordination spheres and coupled by, besides the magnetic dipole-dipole interaction, isotropic exchange: J
nn
= (−197±1)×10−4, J
2nα
= (−5±1)×10−4, and J
2nβ
= (3±2)×10−4 cm−1. Lines due to other isolated Ni2+ ions, which have a different initial splitting D, are also present in the spectrum with intensity comparable to the pair spectrum. Low-symmetry distortions of the crystal
field are observed, caused by a pair of impurity ions located close to one another. It is shown that the previously proposed
interpretation is incorrect.
Fiz. Tverd. Tela (St. Petersburg) 41, 1602–1608 (September 1999) 相似文献