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1.
Axion-like particles(ALPs)are often defined as relatively light pseudoscalar particles and appear in many extensions of the Standard Model.Taking into account constraints on the free parameters from existing searches and explaining the g-2 deviation,we consider the contributions of ALPs with mass in the range of 1.5GeVm_am_h-m_Z to the exclusive Higgs decays h→PZ and h→Pe~+e~-with P being the pseudoscalar mesonsπ~0,η,η',η_c andη_b in a model-independent approach.We find that,in most of the parameter space range,the contributions of ALP to these decay-processes are ver.y small,while in the case of the ALP mass ma approximatel.y equaling the meson mass m_P,the contributions are significantly large.  相似文献   

2.
张世华  陈本永  傅景礼 《中国物理 B》2012,21(10):100202-100202
This paper presents extensions to the traditional calculus of variations for mechanico-electrical systems containing fractional derivatives.The Euler-Lagrange equations and the Hamilton formalism of the mechanico-electrical systems with fractional derivatives are established.The definition and the criteria for the fractional generalized Noether quasisymmetry are presented.Furthermore,the fractional Noether theorem and conseved quantities of the systems are obtained by virtue of the invariance of the Hamiltonian action under the infinitesimal transformations.An example is presented to illustrate the application of the results.  相似文献   

3.
Lepton number violation processes can be induced by the Majorana neutrino exchange, which provide evidence for the Majorana nature of neutrinos. In addition to the natural explanation of the small neutrino masses,Type-I seesaw mechanism predicts the existence of Majorana neutrinos. The aim of this work is to study the B meson rare decays B~+→K~((*))+μ~+μ~-in the Standard Model and its extensions, and then to investigate the same-sign decay process B~+→K~((*)-)μ~+μ~+. The corresponding dilepton invariant mass distributions are calculated. It is found that the dilepton angular distributions could shed light on the properties of new interactions induced by Majorana neutrinos.  相似文献   

4.
In this paper,we present the exact solution of the one-dimensional Schrdinger equation for the q-deformed quantum potentials via the Nikiforov–Uvarov method.The eigenvalues and eigenfunctions of these potentials are obtained via this method.The energy equations and the corresponding wave functions for some special cases of these potentials are briefly discussed.The PT-symmetry and Hermiticity for these potentials are also discussed.  相似文献   

5.
Over the last few years LHCb found some discrepancies in b → sl~+l~-FCNC transitions, including anomalies in the angular observables of B→K~*μ~+μ~-, particularly in P′_5, in the low dimuon mass region. Recently,these anomalies have been confirmed by Belle, CMS and ATLAS. As direct evidence of physics beyond the Standard Model is absent so far, these anomalies are being interpreted as indirect hints of new physics. In this context, we study the implications of the family non-universal Z′ model for the angular observables P_(1,2,3), P′_(4,5,6) and newly proposed lepton flavor universality violation observables, Q_(4,5), in the B → K~*(→Kπ)μ~+μ~-decay channel in the low dimuon mass region. To see the variation in the values of these observables from their Standard Model values, we have chosen different scenarios for the Z′ model. It is found that these angular observables are sensitive to the values of the parameters of the Z′ model. We have also found that with the present parametric space of the Z′ model,the P′_5-anomaly could be accommodated. However, more statistics on the anomalies in the angular observables are helpful to reveal the status of the considered model and, in general, the nature of new physics.  相似文献   

6.
Transparent Yb doped YAG, YSAG and YaLaO3 ceramics are fabricated by using the co-precipitation method. The spectral properties and thermal parameters of these Yb doped cubic phase transparent ceramics are compared, and their different and potential applications are also analysed. The absorption cross-section and the emission cross-section of these ceramics are measured and calculated. The essential properties of these materials especially for the rep-rated pulsed high-energy diode-pumped solid-state lasers are investigated. The results show that Yb doped YAG, YSAG and YaLaO3 are all suitable materials used for diode-pumped solid-state lasers.  相似文献   

7.
The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindrical-confinement-induced phase behaviours of diblock copolymers. A series of lamella-cylinder mixture phases, such as the mixture of broken-lamellae and cylinders and the mixture of square-lamellae and cylinders, are observed by varying the phase parameters, in which the behaviours of these mixture phases are discussed in the corresponding phase diagrams. Fur-thermore, the free energies of these mixture phases are investigated to illustrate their evolution processes. Our results are compared with the available observations from the experiments and simulations respectively, and they are in good agreement and provide an insight into the phase behaviours under cylindrical confinement.  相似文献   

8.
董传华 《中国物理》2003,12(4):408-414
The interactions between coupled atoms and a single mode of a quantized electromagnetic field, which involve the terms originating from the dipole interactions, are discussed. In the usual Jaynes-Cummings model for coupled atoms, the terms of non-conservation of energy originating from dipole interactions are neglected, however, we take them into consideration in this paper. The effects of these terms on the evolutions of quantum statistic properties and squeezing of the field, the squeezing of atomic dipole moments and atomic population inversion are investigated. It has been shown that the coupling between atoms modulates these evolutions of fields and atoms. The terms of non-conservation of energy affect these evolutions of fields and atoms slightly. They also have effects on the squeezing of the field, the squeezing of atomic dipole and atomic population inversions. The initial states of atoms also affect these properties.  相似文献   

9.
The correlation functions of the side - groups and side ?chains of polymers are obtained for nuclear spin relaxation if the segmental motion of the polymers is described by VJGM model, these functions are derived from unequal two ?side and three -site jump internal rotation, diffusion internal rotation, restricted internal rotation and multiple internal rotation. The corresponding spectral density functions are also given, and these functions are used to interpret the nuclear spin relaxation data of the side-groups of some polymers. The average spectral density functions of side-groups are derived under the magic angle spinning, the correlation times and diffusion coefficients of the side-groups of crosslinked poly (methyl methacry-latcs) and solid poly(vinylbutyral) are obtained by using these average spectral density functions. The multiphase structures of nylon 6, poly (ethylenc glycol) and its complexes are investigated with cross ?polarization and magic angle spinning techniques.Three methods using  相似文献   

10.
A long-range broadcasting system may be considered as a system of speech transmission.Theprincipal parameters involved in this system are the average spectrum of speech,the function ofsignal pre-emphasis,the characteristics of electro-acoustic transformation and the attenuation forsound transmission in air.At present,the relations between these parameters and frequency usuallyare described by diagrams or quasi-empirical formulas.In most cases,the interrelations among theseparameters are complicated,and designing the broadcasting system are difficult.In this paper,onthe basis of theoretical derivations and experimental results of these parameters,the approximateanalytic formulas of the relation between these parameters and frequency are obtained by using themethod of curve fitting.It is convenient to design a broadcasting system by using these formulas.As an example,a design method of a broadcasting system for 8—10 km is introduced.  相似文献   

11.
The magnetic and quadrupole moments of the Zc(4020)+,Zc(4050)+,and Zc(4600)+ states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states.The magnetic moments are acquired as μZc=0.50-0.22+0.22μN,μ  相似文献   

12.
Based on the coupled Ginzburg-Landu equation,we numerically investigate the pulse dynamics in a dispersion-managed normal dispersion Tm-doped mode-locked fiber laser.The influences of the modulation depth and saturation power of saturable absorber on the pulse dynamics are presented.The simulation results show that these parameters are crucial to achieve high pulse energy and high pulse peak power pulsed laser near 2-μm wavelength.  相似文献   

13.
Timing system of HIRFL-CSR   总被引:1,自引:0,他引:1  
The national science project HIRFL-CSR has recently been officially accepted. As a cyclotron and synchrotron complex, it puts some particularly high demands on the control system. There are hundreds of pieces of equipment that need to be synchronized. An integrated timing control system is built to meet these demands. The output rate and the accuracy of the controller are 16 bit/μs. The accuracy of the time delay reaches 40 ns. The timing control system is based on a typical event distribution system, which adopts the new event generation and the distribution scheme. The scheme of the timing control system with innovation points, the architecture and the implemented method are presented in the paper.  相似文献   

14.
李宏  王铁军  黄德修  王东宁 《中国物理》2004,13(9):1447-1453
Correlated perturbations are considered in a dark soliton system, and their effects on soliton propagation and interaction are investigated numerically. These perturbations result in large sidebands, lead to submergence of dark soliton, and enhance the interaction. The correlation amplifies these effects and shortens the distance until submergence. The comparison of the distinction is made between the degradations of these effects on dark soliton and the corresponding bright soliton. It is found that these effects on dark soliton are less than those on bright soliton. Finally the nonlinear gain is introduced to suppress efficiently these effects.  相似文献   

15.
The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.  相似文献   

16.
Novel structure GaAs/InGaAs/AlGaAs pseudomorphic modulation-doped field-effect transistors (MODFETs) with a buried p-i-n dipole layer and a 200 nm buffer layer have been fabricated.According to the calculation,the dipole buried layer not only results in the very thin buffer layer required,but also enhances the density of two-dimensional electron gas.The measured transconductances of these MODFETs,with a gate length of 2μm and a drain-source spacing of 5μm,are as high as 320mS/mm and the measured maximum drain currents of the typical devices are higher than 500mA/mm.  相似文献   

17.
黄莉蕾  洪治 《中国物理》2000,9(1):31-36
From transition-rate-equations and transmission-equations the formulas of threshold power are deduced for an end-pumped laser, in which the probability of cross-relaxation cannot be ignored and the nonradiative transition-probability of the excited state is the same order as the radiative transition-probability of upper level of the lasing transition. The lasing performance of Tm:YVO4 at λ=1.9 and 1.5μm is discussed by dint of these equations of threshold power.  相似文献   

18.
When two representations of the Lie algebra are coupled,the coupling integral kernels are presented to relate the coupled to uncoupled group-related coherent states,These kernels have a connection with usual coupling coefficients.The explicit expressions of these kernels for SU(2),SO(4) and SUq(2) are given.When the direct product of three representations is formed in two ways,the recoupling integral kernels relating to the coupled group-related coherent states corresponding to two different schemes are introduced,and the relations between these kernels and the general recoupling coefficients are obtained.The properties of these kerels are discussed.  相似文献   

19.
Semiconductor detectors based on a silicon pin diode are frequently used in the detection of different nuclear radiations. For the detection and dosimetry of fast neutrons, these silicon detectors are coupled with a fast neutron converter. Incident neutrons interact with the converter and produce charged particles that can deposit their energy in the detectors and produce a signal. In this study, three methods are introduced for fast neutron dosimetry by using the silicon detectors, which are: recoil proton spectroscopy, similarity of detector response function with conversion function, and a discriminator layer. Monte Carlo simulation is used to calculate the response of dosimetry systems based on these methods. In the different doses of an 241Am-Be neutron source, dosimetry responses are evaluated. The error values of measured data for dosimetry by these methods are in the range of 15-25%. We find fairly good agreement in the 241Am-Be neutron sources.  相似文献   

20.
Low-amplitude vector screening solitons   总被引:3,自引:0,他引:3  
We show self-coupled and cross-coupled vector beam evolution equations in the low-amplitude regime for screening solitons, which can exhibit the analytical solutions of bright-bright and dark-dark vector solitons. Our analysis indicates that these self-coupled vector solitons are obtained irrespective of the intensities of the two optical beams, whereas these cross-coupled vector solitons can be established when the intensities of the two optical beams are equal. Relevant examples are provided where the photorefractive crystal is lithium niobate (LiNbO3). The stability properties of these vector solitons have been investigated numerically and it has been found that they are stable.  相似文献   

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