共查询到20条相似文献,搜索用时 109 毫秒
1.
Leonard P. Gamberg 《Pramana》2009,72(1):55-68
The naive time reversal odd (‘T-odd’) parton distribution and fragmentation functions are explored. We use the spectator model
framework to study flavour dependence of the Boer-Mulders (h
1⊥ ) and Sivers (f
1T⊥) functions as well as the ‘T-even’ but chiral odd function h
1L⊥. These transverse momentum-dependent parton distribution functions are of significance for the analysis of azimuthal asymmetries
in semi-inclusive deep inelastic scattering, as well as for the overall physical understanding of the distribution of transversely
polarized quarks in unpolarized hadrons. In this context we also consider the Collins mechanism and the fragmentation function
H
1⊥. As a by-product of this analysis we calculate the leading twist unpolarized cos(2ϕ) asymmetry, and sin(2ϕ) single spin asymmetry for a longitudinally polarized target in semi-inclusive deep inelastic scattering.
相似文献
2.
We present predictions of the unweighted and weighted double spin asymmetries related to the transversal helicity distribution
g
1T
and the longitudinal transversity distribution h1L^h_{1L}^{\perp}, two of eight leading-twist transverse momentum dependent parton distributions (TMDs) or three-dimensional parton distribution
functions (3dPDFs), in the polarized proton–antiproton Drell–Yan process at typical kinematics on the Facility for Antiproton
and Ion Research (FAIR). We conclude that FAIR is ideal to access the new 3dPDFs toward a detailed picture of the nucleon
structure. 相似文献
3.
D. É. Fel’dman 《Journal of Experimental and Theoretical Physics》1999,88(6):1170-1178
The critical behavior of the transverse (with respect to the field) magnetization component in classical degenerate magnets
with only nearest-neighbors interaction in a uniaxial random magnetic field at zero temperature is found exactly. For a Gaussian
distribution of the random field the asymptotic transverse magnetization in strong fields does not depend on the dimension
of the space and is of the form m
⊥ ∝ 1nh
0/h
0
2
, where h
0 is the width of the distribution. For a bimodal distribution, where only the field direction is random and the amplitude
is fixed, the transverse magnetization behaves as m
⊥∝exp(−const/(H
c
−H)
D/2), where H is the amplitude of the random field, D is the dimension of the space, and H
c
is the critical field.
Zh. éksp. Teor. Fiz. 115, 2143–2159 (June 1999) 相似文献
4.
We calculate the double spin asymmetry ALL for the π0 production in semi-inclusive deep inelastic lepton–proton scattering with a spectator model of power-law and a model based on the factorization ansatz. We also calculate the double spin asymmetry for the integration over parts of the kinematic range for the setups of the experiments of COMPASS, HERMES, and JLab. We find that the results are characteristically dependent on the model used. Therefore, we suggest that the measurements of the double spin asymmetry provides a method of experimentally probing the transverse momentum dependent distributions. 相似文献
5.
Using a proton-nitrogen double resonance technique we have determined the quadrupole coupling of14N in the room temperature orthorhombic (Cmca), the low temperature tetragonal (P42/ncm), and the monoclinic low temperature (P21/c) phases of (CH3NH3)2CdCl4. In all these phases all nitrogens are chemically equivalent demonstrating that the disorder in the orientations and H-bonding arrangements of the CH3-NH3 groups in theC m c a andP42/ncm phases is indeed dynamic and not static. In the monoclinic phase the14N quadrupole coupling constant equalse
2
qQ/h=880 kHz and the asymmetry parameter is=0.20, wherease
2
qQ/h=790 kHz,=0.1 in the tetragonal low temperature phase ande
2
qQ/h=726 kHz,=0.21 in the room temperature orthorhombic phase. The observed increase in the14N quadrupole coupling constant on going from the orthorhombic phase to the tetragonal low temperature phase which is coupled with a simultaneous decrease in the asymmetry parameter can be understood in terms of a partial freezing in of the dynamic disorder in the C-N bond directions whereas the14N quadrupole coupling tensor in the monoclinic phase is characteristic of a frozen in C-N bond in a deformed lattice, where the N-H — Cl bonds are of different length. 相似文献
6.
Haisheng Li 《Communications in Mathematical Physics》2010,296(2):475-523
This is a paper in a series to study vertex algebra-like structures arising from various algebras including quantum affine
algebras and Yangians. In this paper, we study notions of (h/2p){\hbar}-adic nonlocal vertex algebra and (h/2p){\hbar}-adic (weak) quantum vertex algebra, slightly generalizing Etingof-Kazhdan’s notion of quantum vertex operator algebra. For
any topologically free
\mathbb C[[(h/2p)]]{{\mathbb C}\lbrack\lbrack{\hbar}\rbrack\rbrack}-module W, we study (h/2p){\hbar}-adically compatible subsets and (h/2p){\hbar}-adically S{\mathcal{S}}-local subsets of (End W)[[x, x
−1]]. We prove that any (h/2p){\hbar}-adically compatible subset generates an (h/2p){\hbar}-adic nonlocal vertex algebra with W as a module and that any (h/2p){\hbar}-adically S{\mathcal{S}}-local subset generates an (h/2p){\hbar}-adic weak quantum vertex algebra with W as a module. A general construction theorem of (h/2p){\hbar}-adic nonlocal vertex algebras and (h/2p){\hbar}-adic quantum vertex algebras is obtained. As an application we associate the centrally extended double Yangian of
\mathfrak s\mathfrak l2{{\mathfrak s}{\mathfrak l}_{2}} to (h/2p){\hbar}-adic quantum vertex algebras. 相似文献
7.
The effects of the 57Fe isotope content and high-frequency magnetic field amplitude h
1 on the shape of the NMR spectrum of multiferroic BiFeO3 at T = 4.2 K are studied by pulsed nuclear magnetic resonance. The NMR spectrum shape and transverse relaxation time T
2 are found to depend strongly on the 57Fe isotope content and h
1 in multiferroic BiFeO3 in the presence of a spatial spin-modulated structure of a cycloid type. In a sample with a high 57Fe isotope content, the Suhl-Nakamura interaction contributes substantially to T
2. When these dynamic effects are taken into account for analysis of the NMR spectrum shape, an undisturbed (without an anharmonicity
effect) spatial spin-modulated structure of a cycloid type is shown to exist in BiFeO3. 相似文献
8.
The parton model predicts a jet structure for e+e? annihilation into hadrons. This is obscured at low energies by the presence of finite transverse momentum effects. We suggest studying e++e? → h1+h2+X, where at least one hadron is near the kinematical boundary; this defines a jet axis. Numerous predictions for correlations among mesons follow from Feynman's parton fragmentation suggestion. We also give sum rules which check for the quantum numbers of the partons. 相似文献
9.
S. A. Nazarov 《Acoustical Physics》2010,56(6):1004-1015
We study the discrete spectrum of the Laplace operator with the Dirichlet boundary conditions in a plane waveguide made of
a band of unit width and half-band of width h perpendicular to it. The existence of critical width h
* ∈ (1,2] is established: in the case of h ∈ (0, h*), the discrete spectrum σ
d
h
of the problem contains only one eigenvalur λ1
h
, but σ
d
h
= ⊘ at h ≥ h
*. The asymptotics of the eigenvalue λ1
h
at h → + 0 is found. 相似文献
10.
Estimates for electroproduction of pseudoscalar mesons at small values of skewness are presented. Cross-sections and asymmetries
for these processes are calculated within the handbag approach which is based on factorization in hard parton subprocesses
and soft generalized parton distributions (GPDs). The latter are constructed from double distributions. Transversity GPDs
are taken into account; they are accompanied by twist-3 meson wave functions. For most pseudoscalar-meson channels a combination
of ˜T and [`(E)]T \bar{{E}}_{T}^{} plays a particularly prominent role. This combination of GPDs, which we constrain by moments obtained from lattice QCD, leads,
with the exception of the p+ \pi^{+}_{} and h¢ \eta^{\prime}_{} channels, to large transverse cross-sections. 相似文献
11.
The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d
h
(i)
of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients d
h
(1)
and d′
h
(3)
, were measured, d
h
(1)
=(244±3) pC/N and d′
h
(3)
=(92±1) pC/N. The hydrostatic piezoelectric coefficient d
h
(3)
for orthogonal axis system was calculated to be d
h
(3)
=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d
h
(1)
equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has
been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d
h
)
mean
corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d
h
)
mean
=136 pC/N. 相似文献
12.
B. Cameron Reed 《Central European Journal of Physics》2005,3(1):1-7
The ground-state energy of neutral helium is estimated variationally with a trial wavefunction of the form ϕ≈e
−γ(rA/a
o)ne−γ(rB/a
o)n. This model represents a modification of traditional textbook examinations of this problem via inclusion of the power “n”
as a second nonlinear variational parameter in addition to the usual effective nuclear charge γ and leads to an upper-limit
on the ground state energy of −2.86107 E
h
(E
h
=1 hartree) in comparison with the traditional (n=1) result of −2.84766 E
h
. This result represents a reduction of the percentage overestimate from the true ground-state energy (−2.90373 E
h
) of from 1.93 to 1.47. In comparison with the maximum accuracy obtainable from an uncorrelated trial wavefunction, −2.86168
E
h
, the present trial wavefunction reduces the percentage overestimate from 0.49 (n=1) to 0.021. The optimum values of (n, γ)
are determined to be ≈(0.897, 1.825). 相似文献
13.
V. Barone Zhun Lu Bo-Qiang Ma 《The European Physical Journal C - Particles and Fields》2007,49(4):967-971
We investigate the cos2φ azimuthal asymmetry in Drell–Yan and J/ψ production from unpolarized pp̄ scattering at GSI-HESR energies.
The contribution to this asymmetry arising from the leading-twist Boer–Mulders function (x,k
T
2), which describes a correlation between the transverse momentum and the transverse spin of quarks in an unpolarized hadron,
is explicitly evaluated, and predictions for the GSI-HESR kinematic regime are presented. We show that the cos2φ asymmetry
is quite sizable both on the J/ψ peak and in the Drell–Yan continuum region. Therefore these processes may offer experimentally
viable access to the Boer–Mulders function in the early unpolarized stage of GSI experiments. 相似文献
14.
用铁磁畴壁模型研究了非补偿界面铁磁/反铁磁双层膜中冷却场(包括大小及其方向)对交换偏置场hE的影响.结果表明:当冷却场的方向与反铁磁层磁易轴一致时,hE大小与冷却场大小无关.当冷却场的方向偏离磁易轴时,hE的大小随偏离角度的增大有缓慢的改变,但当冷却场的方向偏离到临界角度γc处,hE的大小发生突变,其γc的大小随冷却场的增大而增大.特别是当冷却场的偏离角度大于γc后,hE出现由负转正的现象,其转变点还与冷却场的大小有关.另外,hE与铁磁层原子层数NF的关系会发生由hE∝N-1F向hE∝N-λF的转变,其中λ>1.其发生转变的条件与NF、冷却场大小和方向密切相关.
关键词:
铁磁/反铁磁双层膜
交换偏置
冷却场 相似文献
15.
R. B. KING 《Molecular physics》2013,111(2):297-302
Geometrical models of double point groups are provided by double-sheeted Riemann surfaces of nonzero genus. This avoids the geometrically confusing picture of the doubling operation R as a rotation by 2π (i.e. 360°), which should instead be the identity operation E. In this manner a Riemann surface of genus 2 doubly covering a sphere and platonically tessellated b 16 equilateral triangles provides a geometrical model for the double octahedral group 2Oh. Stretching this Riemann surface along one axis to convert the 16 equilateral triangles to isosceles triangles and the underlying sphere to a prolate ellipsoid provides a model for the 2D4h double group arising from the Jahn-Teller elongation of the regular octahedron into a prolate tetragonal bipyramid. 相似文献
16.
We consider the see-saw mechanism for hierarchical Dirac and Majorana neutrino mass matrices m
D and M
R, including the CP violating phases. Simple arguments about the structure of the neutrino mass matrix and the requirement of successful leptogenesis lead to the situation that one of the right-handed Majorana neutrinos is much heavier than the other two, which in turn display a rather mild hierarchy. It is investigated how for the neutrino mixing one small and two large mixing angles are generated. The mixing matrix element |U
e3|2 is larger than 10-3 and a characteristic ratio between the branching ratios of lepton flavor violating charged lepton decays
is found. Successful leptogenesis implies sizable CP violation in oscillation experiments. As in the original minimal see-saw model, the signs of the baryon asymmetry of the universe and of the CP asymmetry in neutrino oscillations are equal and there is no connection between the leptogenesis phase and the effective mass as measurable in neutrinoless double beta decay.Received: 28 May 2003, Revised: 13 September 2003, Published online: 26 November 2003 相似文献
17.
C. Foin A. Gizon D. Barnéoud J. Genevey J. Gizon D. Santos F. Farget P. Paris C. F. Liang D. Bucurescu A. Płochocki 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):451-454
The decay of the T
1/2 = 420 ns isomer in 151Er has been reinvestigated. The multipolarities of the decaying transitions have been established by measuring the electron
conversion coefficients. An I
π
= 67/2− assignment is proposed for this isomer with a π[h
112/4
d
32/1
d
52/−1]⊗ν[f
7/2
h
9/2
h
112/−1] configuration. 相似文献
18.
《Physics letters. [Part B]》2008,660(5):458-465
The semi-inclusive difference asymmetry Ah+−h− for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002–2004 using a 160 GeV polarised muon beam scattered off a large polarised 6LiD target in the kinematic range 0.006<x<0.7 and 1<Q2<100 (GeV/c)2. In leading order QCD (LO) the deuteron asymmetry Ah+−h− measures the valence quark polarisation and provides an evaluation of the first moment of Δuv+Δdv which is found to be equal to 0.40±0.07(stat.)±0.06(syst.) over the measured range of x at Q2=10 (GeV/c)2. When combined with the first moment of previously measured on the same data, this result favours a non-symmetric polarisation of light quarks at a confidence level of two standard deviations, in contrast to the often assumed symmetric scenario . 相似文献
19.
Y. Gono A. Odahara T. Fukuchi E. Ideguchi T. Kishida T. Kubo H. Watanabe S. Motomura K. Saito O. Kashiyama T. Morikawa B. Cederwall Y.H. Zhang X.H. Zhou M. Ishihara H. Sagawa 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):5-8
Isomers in N = 83 isotones of Z = 60-66, were studied systematically. Their spins and parities are 49/2+ and 27+ for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a
Z = 64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are [ν(f
7/2
h
9/2
i
13/2),π(h
11/2)2]49/2+ and [ν(f
7/2
h
9/2
i
13/2),π(h
11/2)2(d
5/2)-1]27+ for odd and odd-odd nuclei, respectively. The shape of the yrast states changes suddenly at spin 49/2(odd) and 27(odd-odd)
from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They
may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also
described.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
20.
Frank F. Haas Katharina Vollmayr Kurt Binder 《Zeitschrift für Physik B Condensed Matter》1995,99(1):393-400
As a simple model of an anisotropic orientational glass with short range forces, the 3-state Potts model on the simple cubic
lattice with nearest neighbor interactions drawn from a Gaussian distribution is considered. With Monte Carlo methods we study
the response of the system to a uniform “field” which favors one of the states. This is motivated by experiments which apply
stress that favors one molecular orientation of the quadrupolar glass. The responsem to that fieldh=H/k
BT is analyzed in terms of an expansionm= χ1
h+χ1
h
2+χ1
h
3+..., where χ1 is the linear susceptibility, and χ2,χ13 are nonlinear susceptibilities. Unlike the case of spin glasses, where the spin inversion symmetry of the system in the absence
of fields implies χ2≡0,χ2 is nonzero here and diverges to −∞ at the zero temperature transition of the model, while χ3 diverges to +∞ as in spin glasses. At inifinite temperature, however, χ1=1/3, χ2=1/18 and χ3=-1/54, i.e. the nonlinear susceptibilities have a different sign as at low temperature. In contrast, a random field does
not induce a uniform order parameterm but only a glass order parameterq. The temperature dependence of this glass order parameterq(T) shows for intermediate field strength order parameterq(T) shows for intermediate field strength a maximum of the slopedq(T)/dT very similar to corresponding experiments. 相似文献