共查询到20条相似文献,搜索用时 15 毫秒
1.
G. Pancheri O. Shekhovtsova G. Venanzoni 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):458-460
Effects due to the non-pointlike behaviour of pions in the process e
+
e
-→π
+
π
-
γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution
of the direct decay φ→π
+
π
-
γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE
analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a
model-independent way is proposed. 相似文献
2.
Doubly-charged scalars, predicted in many models having exotic Higgs rep-resentations, can in general have lepton-number violating
(LFV) couplings. We show that by using an associated monoenergetic final state photon seen at a future linear e
−
e
− collider, we can have a clear and distinct signature for a doubly-charged resonance. The strength of the ΔL = 2 coupling can also be probed quite effectively as a function of the recoil mass of the doubly-charged scalar.
相似文献
3.
Santosh Kumar Rai 《Pramana》2007,69(5):815-818
Loop-driven decay modes of the Higgs are sensitive to new physics contributions because of new particles in the loops. To
highlight this we look at the dilepton-dijet signal in the dominant Higgs production channel at a linear e
+
e
− collider. We show that by taking a simple ratio between cross-sections of two different final states such contributions can
be very easily identified.
相似文献
4.
A. Gasparyan J. Haidenbauer C. Hanhart K. Miyagawa 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):61-67
The prospects of utilizing the strangeness production reaction γd→K
+
Λn for the determination of the Λn low-energy scattering parameters are investigated. The spin observables that need to be measured in order to isolate the
Λn singlet (1
S
0) and triplet (3
S
1) states are identified. Possible kinematical regions where the extraction of the Λn scattering lengths might be feasible are discussed. 相似文献
5.
N. N. Achasov 《Physics of Atomic Nuclei》2007,70(5):862-863
It is argued that the realization of gauge invariance condition as a consequent of cancellation between the ϕ → γf
0 → γπ
0
π
0 resonance contribution and the ϕ → γπ
0
π
0 background one, suggested by A.V. Anisovich et al., Yad. Fiz. 68, 1614 (2005), is misleading.
The text was submitted by the author in English. 相似文献
6.
A two-photon impurity absorption coefficient of the “quantum dot — D(−)-center” complexes synthesized in a transparent dielectric matrix is calculated within the model of zero-radius potential.
The evolution of spectral dependence of the absorption coefficient of the nanoheterostructure based on semiconductor CdS
x
Se
1−x
glasses is studied versus the average quantum-dot radius. It is shown that the contribution of the two-photon impurity absorption
to the exited two-photon luminescence is fairly significant at a reasonable quantum-dot concentration.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 46–50, July, 2005. 相似文献
7.
C-field cosmological models based on Hoyle-Narlikar theory with variable gravitational constant G in the frame work of FRW (Friedmann-Robertson-Walker) space–time for positive and negative curvatures are investigated. To
get the deterministic solutions in terms of cosmic time t, we have assumed G=R
n
and discussed for n=−1, −2, R being scalar factor. In both the cases, creation field C increases with time, the gravitational constant G and matter density (ρ) decrease with time in the model (21). In the model (41) G decreases with time and matter density (ρ) is constant. The other physical aspects of the models are also discussed. 相似文献
8.
A. Kanaev L. Museur F. Edery T. Laarmann T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):261-268
We have studied the fluorescence of electronically excited OH*, H* and H2O+* dissociation fragments after VUV excitation ( h
ν≥11.6
eV) of rare-gas clusters (Rg = Ne, Ar) doped with H2O molecules. In contrast to a free molecule, where Balmer H-series dominate the UV-visible spectra, only the OH
*
(
A
2
Σ
+
↦
X
2
Π) emission band is observed in neon clusters. No emission of excited water ions has been observed. We find that while higher
excitation energies (Ne vs. Ar) induce higher vibrational excitation of the OH*
(
A
) fragment, the rotational temperature is lower. This effect is attributed to the difference in the geometric position of the
H2O molecule on the surface or inside the Rg-cluster. The rotational relaxation in neon clusters is rapid while the vibrational
relaxation is slow because of the coupling with the low energy matrix phonons.
Received 7 March 2002 / Received in final form 27 May 2002 Published online 19 July 2002 相似文献
9.
David Kerr 《Communications in Mathematical Physics》2003,232(3):501-534
We introduce notions of dimension and dynamical entropy for unital C
*
-algebras ``metrized' by means of , which are complex-scalar versions of the Lip-norms constitutive of Rieffel's compact quantum metric spaces. Our examples
involve the UHF algebras and noncommutative tori. In particular we show that the entropy of a noncommutative toral automorphism with respect to the
canonical coincides with the topological entropy of its commutative analogue.
Received: 13 February 2002 / Accepted: 20 August 2002 Published online: 22 November 2002 相似文献
10.
A. C. dos Reis 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):474-478
The issue of Kπ and ππ
S-wave amplitude is addressed using decays of D-mesons. Model-independent measurements of the phases of the π
+
π
+ and K
-
π
+
S-wave amplitude from D
+→π
-
π
+
π
+ and D
+→K
-
π
+
π
+ decays are discussed. The result indicates a deviation from the phase of the K
-
π
+
S-wave amplitude obtained by scattering experiments. This could be interpreted as an indication of the presence of 3-body final-state
interaction, or in other words, that the phases from production and scattering process cannot be directly compared. 相似文献
11.
12.
S. Yu. Paranchich L. D. Paranchich M. D. Andriichuk V. R. Romanyuk V. N. Makogonenko Yu. V. Tanasyuk T. A. Mel’nichuk 《Journal of Applied Spectroscopy》2007,74(1):81-85
We present the results of experimental studies of the optical properties of cobalt-doped Cd
x
H1−x
Se (x = 0.18) single crystals with cobalt ion concentrations of NCo = 5·1018, 5·1019, and 1·1020 cm−3 at T = 90 K and 300 K. The composition (x = 0.18) of the Cd
x
Hg1−x
Se solid solution was selected so that the hypothetical resonance level is found on the bottom of the conduction band. We
show that the cobalt ions in the mercury selenide can form a resonance donor level only for cobalt concentrations NCo < 5·1018 cm−3. For NCo ∼ 5·1018 cm−3, the cobalt ions substitute for mercury atoms, forming a solid solution and leading to an increase in the bandgap width and
a change in the physical properties. The solubility of cobalt in the HgSe lattice can be greater than 5%–10%.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 73–77, January–February, 2007. 相似文献
13.
Yong-Yeon Keum 《Pramana》2004,63(6):1151-1170
We discuss applications of the perturbative QCD approach in the exclusive non-leptonic two-bodyB-meson decays. We briefly review its ingredients and some important theoretical issues on the factorization approach. PQCD
results are compatible with present experimental data for charmless B-meson decays. We predict the possibility of large direct
CP asymmetry in B0 → π+π− (23 +7%) and B0 →K
+π− (− 17 ± 5%). We also investigate the branching ratios, CP asymmetry and isospin symmetry breaking in radiativeB →(K*/ρ)γ decays. 相似文献
14.
Zhang XiaoAn Xiao GuoQing Yang ZhiHu Chen XiMeng Zhao YongTao Li FuLi Wang Li Cui Ying Zhang HongQiang Zhan WenLong 《中国科学G辑(英文版)》2008,51(1):82-89
Using the slow highly charged ions 129Xe
q+ (q = 25, 26, 27; initial kinetic T
0⩽4.65 keV/a.u.) to impact Au surface, the Au atomic Mα characteristic X-ray spectrum is induced. The result shows that as
long as the charge state of projectile is high enough, the heavy atomic characteristic X-ray can be effectively excited even
though the incident beam is very weak (nA magnitude), and the X-ray yield per ion is in the order of 10−8 and increases with the kinetic energy and potential energy of projectile. By measuring the Au Mα-X-ray spectra, Au atomic
N-level lifetime is estimated at about 1.33×10−18 s based on Heisenberg uncertainty relation.
Supported by the National Natural Science Foundation of China (Grant Nos. 10574132, 10274088 and 10405025), the Talent Introduction
Project of Xianyang Normal University (Grant No. 05XSYK103) and the Education Commission Foundation of Shaanxi Province (Grant
No. 04JK300) 相似文献
15.
The quantum-well D(−)-states in the presence of magnetic field longitudinal with respect to the growth axis are considered.
Within a model of zero-radius potential, an equation is derived that determines the dependence of the D(−)-state binding energy on the parameters of the potential of the structure, coordinates of the D(−) center, and the magnetic field. The results are compared with the experimental dependence of the D(−)-state binding energy on the magnetic field and the data are shown to be in good agreement with calculations for magnetic
fields B < 10 T. A dimension factor is defined in the dependence of the binding energy on coordinates for the 2D → 1D → 0D transition.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 25–29. 相似文献
16.
A. Yu. Loginov 《Physics of Atomic Nuclei》2011,74(5):740-754
The (1 + 1)-dimensional nonlinear O(3) σ model involving an explicitly broken symmetry is considered. Sphalerons are known to exist in this model. These sphalerons
are of a topological origin and are embedded kinks of the sine-Gordon model. In the case of a compact spatial manifold S
1, sine-Gordon multikinks exist in the model. It is shown that the model admits a nonstatic generalization of the sine-Gordon
kink/multikink, Q kink/multikink. Explicit expressions are obtained for the dependence of the Q kink energy and charge on the phase frequency of rotation. The Q kink is studied for stability, and expressions are obtained for the eigenfunctions and eigenfrequencies of the operator of
quadratic fluctuations. It is shown that the Q kink is unstable over the entire admissible frequency range ω ∈ [−1, 1]. The one-loop quantum correction to the static-kink mass is calculated, and the Q-kink zero mode is quantized. It is shown that, in a general static case, the field equations of the model are integrable
in quadratures. 相似文献
17.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):229-241
We utilize existing inclusive data on K+-meson momentum spectra of the reaction pp→K
+
X at T
p = 2.3-2.85GeV to deduce total cross-sections for pp→K
+
Σ
+
n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T
p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained
for T
p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration
at a somewhat lower beam energy, indicating that the pp→K
+
Σ
+
n reaction cross-section could exhibit a rather unusual energy dependence. 相似文献
18.
The concept of ‘D-Differentiation’, which, in the context of smooth manifolds, generalises Lie and covariant differentiation, is extended to
R
∞ -supermanifolds under the name of ‘Super D-Differentiation’. This is done by defining new (non-linear) mappings, called ‘μ-mappings’ and by relating their non-linearity to the Leibniz rule that a derivation must satisfy when it acts on a tensor
product. The resulting axiomatics, which is basis-independent and coordinate-free, is then expressed in a general basis (not
necessarily holonomic). Super Lie and Super covariant differentiation are, amongst others, special cases of Super D-Differentiation. In particular, the transformation rules for the connection coefficients and the commutation coefficients
of non-holonomic bases are obtained. These special cases are found to be in agreement with the DeWitt Super covariant and
Super Lie derivatives.
相似文献
19.
V. E. Tarasov V. V. Khabarov A. E. Kudryavtsev V. M. Weinberg 《Physics of Atomic Nuclei》2008,71(8):1410-1423
The Kd reactions are considered in the impulse approximationwithNN final-state interactions (FSI) taken into account. Realistic parameters for the KN phase shifts are used. The “quasi-elastic” energy region, in which the elementary KN interaction is predominantly elastic, is considered. The theoretical predictions are compared with the data on the K
+
d → K
+
pn, K
+
d → K0
pp, K
+
d → K
+
d, and K
+
d total cross sections. The NN FSI effect in the reaction K
+
d → K
+
pn has been found to be large. The predictions for the Kd cross sections are also given for slow kaons, produced from ϕ(1020) decays, as the functions of the isoscalar KN scattering length a
0. These predictions can be used to extract the value of a
0 from the data.
The text was submitted by the authors in English. 相似文献
20.
R. Escribano 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):454-457
The scalar contributions to the radiative decay φ→K
0ˉ0
γ are studied within the framework of the Linear Sigma Model (LσM). Theoretical predictions for the associated subprocesses φ→f
0
γ and φ→a
0
γ as well as the ratio φ→f
0
γ/a
0
γ are also given. 相似文献