On the anomalous scattering of μ-mesons

The inelastic scattering of μ-mesons with excitation of the “giant” nuclear dipole resonance and its influence on the large angle scattering of μ-mesons are discussed. It is concluded that the Williams virtual photon method in its original form is not applicable to problems of this kind and that the excitation of “giant” dipole resonances is unable to explain the observed large angle scattering.     

On radiative corrections to inelastic e−p scattering

We show that the so called peaking approximation used in making radiative corrections is not applicable for inelastic e⁻p scattering when the energy of the incoming electron is very high, in fact it is shown, that none of the formulas usually used for performing the radiative corrections to inelastic e⁻p scattering is the result of a peaking approximation. The reason for the failure of the peaking approximation is explained and a method to improve the accuracy of the radiative corrections is proposed.     

Weinbergʼs approach to nucleon–nucleon scattering revisited

We propose a new, renormalizable approach to nucleon–nucleon scattering in chiral effective field theory based on the manifestly Lorentz invariant form of the effective Lagrangian without employing the non-relativistic expansion. For the pion-less case and for the formulation based on perturbative pions, the new approach reproduces the known results obtained by Kaplan, Savage and Wise. Contrary to the standard formulation utilizing the non-relativistic expansion, the non-perturbatively resummed one-pion exchange potential can be renormalized by absorbing all ultraviolet divergences into the leading S-wave contact interactions. We explain in detail the differences to the non-relativistic formulation and present numerical results for two-nucleon phase shifts at leading order in the low-momentum expansion.     

On the application of wavelet transform to the solution of integral equations for acoustic radiation and scattering

1 IlltroductionIt is well Anown that Boundary Element Method (BEM), based on boundary integralequation, leads the reduction of the dimensionallty of the problem by one because the prob1emis formulated in terms of the flelds on botmdary ouly BEM, hOWver, generates algebraicequations with full matrices, whose solutions are moe eapensive than that of the bandedmatrices of FEM[1'2]. On the other hand, in boundary integral forInulations, an integral operatorhas the global behavior, that can b…     

Resonance chiral theory for low-energy ππ scattering

The scattering of a pion on a pion in the energy region $\sqrt s $ ≤1 GeV is successfully described on the basis of pole diagrams featuring spinless, spin-1, and spin-2 intermediate particles, provided that the properties of these particles and of their interactions are deduced from the basic principles of QCD and from the requirements of chiral theory.     

High-precision covariant one-boson-exchange potentials for np scattering below 350 MeV

Using the covariant spectator theory (CST), we have found one-boson-exchange (OBE) potentials that fit the 2006 world np data below 350?MeV with a χ²/N _data very close to 1, for a total of 3788 data. Our potentials have significantly fewer adjustable parameters than previous high-precision potentials, and they also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces.     

On the Euclidean approach to quantum field theory in Gödel space-time

Features of the quantum field theory in the background of the Gödel space-time are investigated. By using the Euclidean approach, a quantum field propagating in this background is found to possess a temperature proportional to the magnitude of the cosmic vorticity. However, in the semiclassical approximation, the Gödel solution does not present an intrinsic entropy.     

Non-perturbative chiral approach to K−p → γY reactions

A recently developed non-perturbative chiral approach to describe the S = −1 meson-baryon reactions has been extended to investigate the near threshold K⁻p → γΛ,γΣ⁰ reactions. With the parameters governed by chiral SU(3) symmetry, we show that the predicted branching ratios Γ_K⁻p→γΛ/Γ_K⁻p→all and Γ_{K⁻p→γΣ⁰}/Γ_K⁻p→all are close to the experimental values. The coupling with the η channels, which was shown to be important in the S = −1 meson-baryon reactions, is also found to be significant here. Our results are consistent with the interpretation of the Λ(1405) as a quasi-bound meson-baryon state as found in other similar chiral approaches.     

N/D approach to πN scattering in the P11 state with short-range forces

The πN scattering in the P₁₁ state is treated in an one-channel N/D approach in elastic approximation. It is shown that the compositeness condition δ₁₁(∞) = −π for the nucleon and the zero of δ₁₁(ω) in the low-energy region can be made consistent with each other by taking into account short-range forces appropriately. We find (without introducing a CDD pole or a cut-off) for a given nucleon-pole position and given contributions from N, N¹ and ϱ exchange, the required value for the πN coupling constant and two zeros of δ(ω) for physical ω, one of them in the low-energy region at the right position. The parameters of the short-range forces approximated by a pole term are fixed by asymptotic conditions on the behaviour of the scattering amplitude at large energies.     

Λc*in a coupled-channel baryon-meson scattering

Possible structures and properties of some excited states of Λc+dynamically generated in the coupled-channel P-wave meson-baryon scattering are studied by solving the Bethe-Salpeter(BS)equation in the framework of the Chiral Unitary Approach.It is shown that both Λc+(2765)and Λc+(2940)could be generated dynamically and could be compound states with multi-configuration molecular-like structures.The couplings of the generated states to various reaction channels are also calculated.Moreover,two highly excited states,Λc+(3024)and Λc+(3134),are predicted.     

∧c^＊ in a coupled-channel baryon-meson scattering

Possible structures and properties of some excited states of Λ_c⁺ dynamically generated in the coupled-channel P-wave meson-baryon scattering are studied by solving the Bethe-Salpeter(BS) equation in the framework of the Chiral Unitary Approach. It is shown that both Λ_c⁺(2765) and Λ_c⁺(2940) could be generated dynamically and could be compound states with multi-configuration molecular-like structures. The couplings of the generated states to various reaction channels are also calculated. Moreover, two highly excited states, Λ_c⁺(3024) and Λ_c⁺(3134), are predicted.     

Origin of Dynamically Generated Baryon Rsonances

We study the origin of baryon resonances which are dynamically generated in the chiral unitary approach.We propose a natural renormalization scheme for the dynamical generation of resonances using the low energy chiral interaction and a general feature of the scattering theory.A deviation of a phenomenological scattering amplitude from the natural one is interpreted by an effective pole term interaction of genuine nature which can not be described by the meson-baryon dynamics,reminiscent of the CDD pole.Applying the present method to physical meson-baryon scatterings,we find that the ∧(1405) resonance is dominated by a meson-baryon component forming a (K)N-π∑ molecular-like structure,while the N(1535) resonance requires some pole contribution.     

The Ξ~* K and ?η Interaction Within a Chiral Unitary Approach

In this work we study the interaction of the coupled channels ?η and Ξ* ˉK within the chiral unitary approach.The systems under consideration have total isospins 0,strangeness S =-3,and spin 3/2.We study the s wave interaction which implies that the possible resonances generated in the system can have spin-parity JP= 3/2-.The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances.We find there is a dynamically generated 3/2-? state with mass around 1800 Me V,which is in agreement with the predictions of the five-quark model.     

Improved Analytical Approximations to the Scattering Solutions of the Schrdinger Equation with a Hyperbolical Potential

Using an improved approximate formula to the centrifugal term, we present arbitrary l-state scattering solutions of the hyperbolic potential. The approximate analytical formula of scattering phase shifts and normalized wavefunctions are presented. All data calculated by the above approximate analytical formula are compared with those obtained by using the numerical integration method in the scattering state cases. We find that this improved approximate formula is better than previous one since the calculated results are in good agreement with those exact ones.     

矢量介子和重子八重态相互作用及其动力学生成的共振态的分波分析（英文）

研究了t道、s道、u道和由张量相互作用项导致的接触项对矢量介子和重子八重态之间的相互作用势的贡献。在分波分析的框架下,求解了耦合道的李普曼–施温格方程,研究了动力学生成的奇异数S=0,同位旋为I=1/2的重子共振态N(1650)1/2-和N(1700)3/2-,N(1895)1/2-和N(1875)3/2-,N(2120)3/2-,以及同位旋I=3/2的重子共振态△(1620)1/2-和△(1700)3/2-的质量、衰变宽度、和角动量等性质。另外,计算结果表明,在2 000 Me V附近存在着JP=1/2-的N(2120)3/2-的对偶共振态。     

在手征么正模型中0+重介子是否存在分子态结构

在分子态结构的假设下, 利用手征么正模型研究了D₀(2308)和B₀的可能结构. 通过研究重子-赝标介子相互作用, 找到了一些可能的分子态. 结果表明: 在带奇异数的系统中, 存在一个质量为2.312±0.041GeV的DK束缚态, 它可以被解释为实验上发现的D_s0(2317). 与此同时, 在非奇异系统中, 存在一个与之对应的、质量为2.1GeV的宽度较大的态和一个对应的、质量为2.44GeV的宽度较小的态. 这两个态应对应于D₀. 因此, 分子态结构只能是D₀(2308)一个分量. 计算结果还预言了一些B_s0和B₀态. 其中质量为5.725±0.039GeV的BK束缚态可以被解释为B_s0(5725), 而预言的B₀(5536)和B₀(5819)应为与B_s0(5725)相对应的非奇异态.