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1.
Alexander Bershadskii 《Journal of statistical physics》2007,128(3):721-739
An analytic perturbation theory is suggested in order to find finite-size corrections to the scaling power laws. In the frame
of this theory it is shown that the first order finite-size correction to the scaling power laws has following form , where η is a finite-size scale (in particular for turbulence, it can be the Kolmogorov dissipation scale). Using data of
laboratory experiments and numerical simulations it is shown shown that a degenerate case with α 0=0 can describe turbulence statistics in the near-dissipation range r > η, where the ordinary (power-law) scaling does not apply. For moderate Reynolds numbers the degenerate scaling range covers
almost the entire range of scales of velocity structure functions (the log-corrections apply to finite Reynolds number). Interplay
between local and non-local regimes has been considered as a possible hydrodynamic mechanism providing the basis for the degenerate
scaling of structure functions and extended self-similarity. These results have been also expanded on passive scalar mixing
in turbulence. Overlapping phenomenon between local and non-local regimes and a relation between position of maximum of the
generalized energy input rate and the actual crossover scale between these regimes are briefly discussed.
PACS: 47.27.-i, 47.27.Gs. 相似文献
2.
On the basis of some general assumptions on the deep inelastic structure functions, such as scaling and chiral symmetry we
determine the values of {(H
V
3)2+(H
A
3)2}+η{(H
V
0)2+(H
A
0)2} andH
V
3
H
A
3+ηH
V
0
H
A
0 whereH
V
3,0 andH
A
3,0 are the four coupling constants characterizing the hadronic neutral current andη is the ratio of the isoscalar to isovector structure functions. General expressions are given for the kinematical averages
〈v〉 and 〈Q
2〉 for the neutral-current reactions in terms of the coupling constants. This analysis does not depend on the validity of the
quark-parton model. 相似文献
3.
《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):195-207
The photoproduction of η -mesons off 12C , 40Ca , 93Nb , and
nat
Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2GeV. The experiment was performed at
the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties
of the S
11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for η -mesons. Careful consideration
was given to contributions from ηπ final states and secondary production mechanisms of η -mesons, e.g. from inelastic πN reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross-section
for η -mesons is constant over a wide range of the η momentum. The comparison of the excitation functions to data off the
deuteron and to calculations in the framework of a BUU model show no unexplained in-medium modifications of the S
11(1535) . 相似文献
4.
E.T. Seppälä M.J. Alava 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(3):407-424
We study the effect of an external field on (1 + 1) and (2 + 1) dimensional elastic manifolds, at zero temperature and with
random bond disorder. Due to the glassy energy landscape the configuration of a manifold changes often in abrupt, “first order”-type
of large jumps when the field is applied. First the scaling behavior of the energy gap between the global energy minimum and
the next lowest minimum of the manifold is considered, by employing exact ground state calculations and an extreme statistics
argument. The scaling has a logarithmic prefactor originating from the number of the minima in the landscape, and reads ΔE
1∼L
θ[ln(L
z
L
- ζ)]-1/2, where ζ is the roughness exponent and θ is the energy fluctuation exponent of the manifold, L is the linear size of the manifold, and Lz is the system height. The gap scaling is extended to the case of a finite external field and yields for the susceptibility
of the manifolds ∼L
2D + 1 - θ[(1 - ζ)ln(L)]1/2. We also present a mean field argument for the finite size scaling of the first jump field, h
1∼L
d - θ. The implications to wetting in random systems, to finite-temperature behavior and the relation to Kardar-Parisi-Zhang non-equilibrium
surface growth are discussed.
Received December 2000 and Received in final form April 2001 相似文献
5.
《Pramana》2003,61(5):865-876
Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies
for a large span of pseudorapidities, |η| < 5.4. Three empirical observations have emerged from this data set which require
theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central
Au + Au collisions, when expressed as dN/dη′ ( η′ ≡ – ybeam), becomes energy independent at high energy for a broad region of η′ around η′ = 0. This energy-independent region grows
with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity
between particle production in e+e−and Au + Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles
and the longitudinal distribution of produced particles are approximately the same in e+e−and in scaled Au + Au. This observation This presentation is based in large part on the PHOBOS summary talk by M Baker at
the16th Int. Conf. on Ultrarelativistic Nucleus- Nucleus Collisions, Quark Matter 2002, Nantes, France was not predicted and has not been explained. Finally, particle production has been found
to scale approximately with the number of participating nucleon pairs for (N
part
) > 65. This scaling occurs both for the total multiplicity and for highp
T
particles (3 <p
T
< 4.5 GeV/c).
This presentation is based in large part on the PHOBOS summary talk by M Baker at the16th Int. Conf. on Ultrarelativistic Nucleus-Nucleus Collisions, Quark Matter 2002, Nantes, France 相似文献
6.
The streamwise fluctuating velocity in the turbulent boundary layer is measured under approximately medium Reynolds Number
by hot wire in order to investigate the scaling properties of the overlapped turbulent spectrum among energy-containing area,
inertial subrange and dissipation range based on FFT analysis. The experiment indicates that the high Reynolds flow reported
before is not indispensable to produce −1 scaling. So far as the measured position is provided with much higher spatial resolution
and enough closing to the wall, −1 scaling is determinate to exist when approaching medium Reynolds. The scaling ranges are
supposed to begin at inner scale and end in outer scale, which reveals the local similarity of the energy spectrum over the
energy-containing eddies near the wall. In the logarithmic area (y
+ > 130), −5/3 scaling occurs in the energy spectrum, while moving away from the wall with Reynolds numbers increasing, the
inertial subrange extends to the lower wavenumbers. On the condition k
1
η ≫ 0.1, the curves of the turbulence spectrum in the logarithmic layer are superposed, which expresses the similarity of turbulence
energy distributed in Komogorov scaling area and exhibits local isotropy characteristics by virtue of the viscous dissipation.
Supported by the National Natural Science Foundation of China (Grant Nos. 10832001 and 10872145), the Program for New Century
Excellent Talents in Universities of Education Ministry of China, and the Plan of Tianjin Science and Technology Development
(Grant No. 06TXTJJC13800) 相似文献
7.
Hatem Zaag 《Communications in Mathematical Physics》2002,225(3):523-549
We consider u(x,t) a solution of u
t
=Δu+|u|
p
− 1
u that blows up at time T, where u:ℝ
N
×[0, T)→ℝ, p>1, (N−2)p<N+2 and either u(0)≥ 0 or (3N−4)p<3N+8. We are concerned with the behavior of the solution near a non isolated blow-up point, as T−t→ 0. Under a non-degeneracy condition and assuming that the blow-up set is locally continuous and N−1 dimensional, we escape logarithmic scales of the variable T−t and give a sharper expansion of the solution with the much smaller error term (T−t)1, 1/2−η for any η>0. In particular, if in addition p>3, then the solution is very close to a superposition of one dimensional solutions as functions of the distance to the blow-up
set. Finally, we prove that the mere hypothesis that the blow-up set is continuous implies that it is C
1, 1/2−η for any η>0.
Received: 20 June 2001 / Accepted: 6 October 2001 相似文献
8.
Final state interaction effects inpp→ pΛK
+ andpd →3Heη reactions are explored near threshold to study the sensitivity of the cross-sections to thepΛ potential and theηN scattering matrix. The final state scattering wave functions between Λ andp andη and3He are described rigorously. The Λ production is described by the exchange of one pion and aK-meson between two protons in the incident channel. Theη production is described by a two-step model, where in the first step a pion is produced. This pion then produces anη by interacting with another nucleon 相似文献
9.
Neeraj Gupta M. Sharma S. Dogra S. Singh N. K. Pruthi L. Kumar 《Indian Journal of Physics》2011,85(1):105-110
We present the measurement of multiplicity and pseudorapidity distributions of photons production at forward rapidity (−2.3
≤ η ≤ −3.8) for Cu + Cu collisions at $
\sqrt {S_{NN} }
$
\sqrt {S_{NN} }
= 62.4 and 200 GeV. Photons are measured using the Photon Multiplicity Detector (PMD) in STAR experiment at RHIC. The distributions
of (η−η
beam), where η
beam is beam rapidity is presented. Pseudorapidity distributions of photons at forward rapidities, when ob-served in the frame
of one of the colliding particles show the signature of energy independent scaling at forward rapidities known as Limiting
Fragmentation. Measurement of inclusive photons reflect the distribution for π
0 as most of the photons come from π
0 decay. Gluon saturation at initial conditions of the collisions is one of the possible explanations for this scaling. Study
of system-size and incident energy dependence of this phenomenon help us understand the mechanisms better. The system-size
and energy dependence of the widths of scaling in pseudorapidity and comparison with model predictions are presented. 相似文献
10.
We consider high-order correlation functions of the passive scalar in the Kraichnan model. Using the instanton formalism,
we find the scaling exponents ζn of the structure functions S
n
for n≫1 under the additional condition dζ2≫1 (where d is the dimensionality of space).At n<n
c
(where n
c
=dζ2/[2(2−ζ2)]) the exponents are ζn=(ζ 2/4)(2n−n
2/n
c
), while at n>n
c
they are n-independent: ζ n=ζ2
n
c
/4. We also estimate the n-dependent factors in S
n
.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 7, 588–593 (10 October 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
11.
《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):241-244
The helicity dependence of the γ
p↦pη reaction has been measured for the first time at a center-of-mass angle θ*
η = 70° in the photon energy range from 780 MeV to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector
system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. The helicity 3/2 cross-section
is found to be small and the results for helicity 1/2 agree with predictions from the MAID analysis.
Received: 19 December 2002 / Accepted: 10 March 2003 / Published online: 20 May 2003 相似文献
12.
B. Dubrulle F. Hersant 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):379-386
We generalize an analogy between rotating and stratified shear flows. This analogy is summarized in Table 1. We use this analogy
in the unstable case (centrifugally unstable flow vs. convection) to compute the torque in Taylor-Couette configuration, as a function of the Reynolds number. At low Reynolds
numbers, when most of the dissipation comes from the mean flow, we predict that the non-dimensional torque G = T/ν2
L, where L is the cylinder length, scales with Reynolds number R and gap width η, G = 1.46η3/2(1 - η)-7/4
R
3/2. At larger Reynolds number, velocity fluctuations become non-negligible in the dissipation. In these regimes, there is no
exact power law dependence the torque versus Reynolds. Instead, we obtain logarithmic corrections to the classical ultra-hard (exponent 2) regimes: G = 0.50
. These predictions are found to be in excellent agreement with avail-able experimental data. Predictions for scaling of velocity
fluctuations are also provided.
Received 7 June 2001 and Received in final form 7 December 2001 相似文献
13.
Infrared asymptotic behavior of a scalar field, passively advected by a random shear flow, is studied by means of the field
theoretic renormalization group and the operator product expansion. The advecting velocity is Gaussian, white in time, with
correlation function of the form μ d(t-t¢) / k^d-1+x\propto\delta(t-t') / k_{\bot}^{d-1+\xi}, where k
⊥=|k
⊥| and k
⊥ is the component of the wave vector, perpendicular to the distinguished direction (‘direction of the flow’)—the d-dimensional generalization of the ensemble introduced by Avellaneda and Majda (Commun. Math. Phys. 131:381, 1990). The structure functions of the scalar field in the infrared range exhibit scaling behavior with exactly known critical
dimensions. It is strongly anisotropic in the sense that the dimensions related to the directions parallel and perpendicular
to the flow are essentially different. In contrast to the isotropic Kraichnan’s rapid-change model, the structure functions
show no anomalous (multi)scaling and have finite limits when the integral turbulence scale tends to infinity. On the contrary,
the dependence of the internal scale (or diffusivity coefficient) persists in the infrared range. Generalization to the velocity
field with a finite correlation time is also obtained. Depending on the relation between the exponents in the energy spectrum
E μ k^1-e\mathcal{E} \propto k_{\bot}^{1-\varepsilon} and in the dispersion law w μ k^2-h\omega\propto k_{\bot}^{2-\eta}, the infrared behavior of the model is given by the limits of vanishing or infinite correlation time, with the crossover
at the ray η=0, ε>0 in the ε–η plane. The physical (Kolmogorov) point ε=8/3, η=4/3 lies inside the domain of stability of the rapid-change regime; there is no crossover line going through this point. 相似文献
14.
O. Bartholomy R. Bogendörfer V. Credé I. Fabry A. V. Anisovich G. Anton R. Bantes Y. A. Beloglazov R. Castelijns A. Ehmanns J. Ernst H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. B. Gridnev E. Gutz S. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. V. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. V. Novinski M. Ostrick H. van Pee A. K. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,33(2):133-146
Photoproduction of η -mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75
to 3GeV. Total and differential cross-sections are presented. The η mesons are detected in two decay modes, in η → 2γ and
in η → 3π0 → 6γ . The cross-sections vary slowly as functions of energy and η production angle suggesting that only few resonances make
significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong
forward peak due to meson exchanges in the t channel. A comparison of the η -photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis
performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests
that the largest contribution to η photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535)S
11 , via N(1720)P
13 , and a newly suggested N(2070)D
15 . 相似文献
15.
Pulak Ranjan Giri 《International Journal of Theoretical Physics》2008,47(10):2583-2590
We argue that it is possible to bind neutral atom (NA) to the ferromagnetic wire (FW) by inequivalent quantization of the
Hamiltonian. We follow the well known von Neumann’s method of self-adjoint extensions (SAE) to get this inequivalent quantization,
which is characterized by a parameter Σ∈ℝ(mod2π). There exists a single bound state for the coupling constant η
2∈[0,1). Although this bound state should not occur due to the existence of classical scale symmetry in the problem. But since
quantization procedure breaks this classical symmetry, bound state comes out as a scale in the problem leading to scaling
anomaly. We also discuss the strong coupling region η
2<0, which supports bound state making the problem re-normalizable. 相似文献
16.
Z.-Q. Jiang L. Guo W.-X. Zhou 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(3):347-355
A phenomenological investigation of the endogenous and
exogenous dynamics in the fluctuations of capital fluxes is carried
out on the Chinese stock market using mean-variance analysis,
fluctuation analysis, and their generalizations to higher orders.
Non-universal dynamics have been found not only in the scaling
exponent α, which is different from the universal values 1/2
and 1, but also in the distributions of the ratio η=
σexo / σendo of individual stocks. Both
the scaling exponent α of fluctuations and the Hurst exponent
Hi increase in logarithmic form with the time scale Δt
and the mean traded value per minute 〈fi 〉,
respectively. We find that the scaling exponent αendo
of the endogenous fluctuations is independent of the time scale.
Multiscaling and multifractal features are observed in the data as
well. However, the inhomogeneous impact model is not verified. 相似文献
17.
The multiplicity dependence of inclusive spectra of identified hadrons (π, K,
, K
S
0
, and Λ) produced in high-energy
p and pp collisions is studied. Analysis of experimental data on high-p
T hadron cross sections obtained at the Tevatron and RHIC is performed in the framework of z scaling. Independence of the scaling function ψ(z) on the multiplicity density dN
ch/dη is established. The multiplicity density measured in nucleon-nucleon collisions reaches much higher values than the corresponding
quantity [1/(0.5N
p)]dN
ch/dη obtained in heavy-ion collisions. Its influence on particle production reveals properties of self-similarity and fractality.
The relation between the scaling variable z and thermodynamic quantities (“heat capacity” and “temperature”) of the medium associated with the produced inclusive particle
is discussed. Search for z-scaling violation in
p and pp collisions at very high multiplicities as an indication of new-physics phenomena is suggested.
The text was submitted by the authors in English. 相似文献
18.
V. Bernard N. Kaiser Ulf-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):259-275
We evaluate the threshold matrix–element for the reaction pp→ppπ0 in a fully relativistic Feynman diagrammatic approach. We employ a simple effective range approximation to take care of the
S–wave pp final–state interaction. The experimental value for the threshold amplitude A = (2.7 −i0.3) fm4 can be reproduced by contributions from tree level chiral (long–range) pion exchange and short–range effects related to vector
meson exchanges, with ω-exchange giving the largest individual contribution. Pion loop effects appear to be small. We stress
that the commonly used heavy baryon formalism is not applicable in the NN–system above the pion production threshold due to
the large external momentum, |p|≃ (Mm
π)−1/2, with M and m
π the nucleon and the pion mass, respectively. We furthermore investigate the reaction pp→pnπ+ near threshold within the same approach. We extract from the data the triplet threshold amplitude as B = (2.8 −i1.5) fm4. Its real part can be well understood from (relativistic) tree level meson–exchange diagrams. In addition, we investigate
the process pp→ppη near threshold. We use a simple factorization ansatz for the ppη final–state interaction and extract from the data the modulus of the threshold amplitude, |C|= 1.32 fm4. With g
ηN= 5.3, this value can be reproduced by (relativistic) tree level meson–exchange diagrams and η–rescattering, whose strength
is fixed by the ηN scattering length. We also comment on the recent near threshold data for η′–production.
Received: 27 November 1998 相似文献
19.
《The European Physical Journal A - Hadrons and Nuclei》2007,33(2):147-155
The beam asymmetry, Σ , was measured at ELSA in the reaction
p → ηp using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented
to provide polarised photons in the energy range E
γ = 800 to 1400MeV with the maximum polarisation of P
γ = 49 % obtained at 1305MeV. Both dominant decay modes of the η into two photons and 3π0 were used to extract the beam asymmetry from the azimuthal modulation of the cross-section. The measurements cover the angular
range Θcm ≃ 50 -150 degrees. Large asymmetries up to 80% are observed, in agreement with a previous measurement. The eta-MAID model
and the Bonn-Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly. 相似文献
20.
We substantially apply the Li criterion for the Riemann hypothesis to hold. Based upon a series representation for the sequence
{λk}, which are certain logarithmic derivatives of the Riemann xi function evaluated at unity, we determine new bounds for relevant
Riemann zeta function sums and the sequence itself. We find that the Riemann hypothesis holds if certain conjectured properties
of a sequence ηj are valid. The constants ηj enter the Laurent expansion of the logarithmic derivative of the zeta function about s=1 and appear to have remarkable characteristics. On our conjecture, not only does the Riemann hypothesis follow, but an inequality governing the values λn and inequalities for the sums of reciprocal powers of the nontrivial zeros of the zeta function.
Mathematics Subject Classification (2000) 11M26. 相似文献