The Pomeron and the scaling law for partial wave amplitudes

From the scaling law for the s-channel partial wave amplitudes, which guarantees simultaneously t-channel unitarity at threshold t = 4μ² and s-channel unitarity, we derive: (i) The intercept α(0) of the Pomeron is always one, if α(4μ²) > 1. (ii) The total and the elastic cross sections are bounded from below for s → ∞.

where α(4μ²) and δ(4μ²) are the position and the type of te Pomeron singularity (J ? α(4μ²))^{?1?δ(4μ2) at t = 4μ2}. (iii) The type of the Pomeron singularity δ(4μ²) is restricted: either $\text{δ(4μ}{}^2\text{) ?}\text{1}\text{2}$ or $\text{δ(4μ}{}^2\text{) ?}\text{1}\text{2}$.     

Integral constraints for partial wave amplitudes from crossing symmetry

By use of crossing symmetry, integral relations among partial wave amplitudes for elastic scattering of self-conjugate mesons are derived. They involve the amplitudes for unphysical values ofs between the pseudothreshold (m-μ)² and the threshold (m+μ)².     

Integral sum rules and inequalities for ππ partial wave amplitudes

Exact integral relations on all ππ partial waves are derived from crossing symmetry. As a corollary we also derive an infinite number of inequalities fors-wave amplitudes.     

Inequalities on left-hand discontinuities of pion-pion partial wave amplitudes

The partial wave crossing relations derived by Balachandran and Nuyts are used to derive inequalities among integrals over left-hand discontinuities of elastic pionpion scattering, weighted by Jacobi functions of the second kind. The only other input for these inequalities are — besides isospin — positivity and boundedness of the right-hand imaginary parts. It is pointed out that similar inequalities follow directly from recent inequalities of Martin.     

Phenomenology of S and P pion-pion partial wave amplitudes

A scheme of parametrization ofππ S andP partial wave amplitudes is proposed. Analytic, crossing and unitarity properties are rigorously satisfied. The analyticity property is made explicit by the use of a conformally mapped variable. Our expressions fit excellently with both phase shift and inelastic curves for centre of mass energy up to 1·4 GeV.     

A partial wave dispersion relation analysis of pion-nucleon scattering amplitudes

Partial wave dispersion relations have been evaluated, using various new πN partial wave solutions and our results for the ππN \(\bar N\) amplitudes. The Karlsruhe-Helsinki 80 and CMU-LBL-79 solution forS, P, D, F waves are well compatible with this constraint, which follows from the Mandelstam representation. The VPI 80 solution leads to serious discrepancies in some cases, for instance for the P11 wave.—In both, the KH 80 and CMU-LBL 79, solutions the higher partial waves are not yet satisfactory. They can be improved by adding constraints based on the information on the nearby part of the left hand cuts.—Properties of nucleon resonances are discussed in connection with our results for the “generalized potentials”.     

On the behavior of the πN partial wave amplitudes ats=0

The behavior of theπN partial wave amplitudes in the limitss→+0 ands→? 0 is related to backward scattering in thes- andt-channel, respectively. Assuming Mandelstam analyticity we prove with the aid of the Phragmen-Lindelöf theorem that the amplitudes for high energy backward scattering inπN→πN andππ→N¯N are equal and therefore dominated by the same exchange mechanism, namely Reggeized Fermion exchange. The dominating Regge trajectory is the Δ_δ-trajectory, and it is shown that theπN partial wave amplitudes diverge fors→±0 as \(s^{ - \alpha \Delta _\delta (0) - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0em} 2}} \) . — Reduced amplitudes are defined which are regular ats=0. — Using recent results ofπN backward scattering real and imaginary part of thes-wave amplitudef ₀₊ ^(?) are calculated in the interval 0≦s≦7.     

Absence of long-range order with long-range potentials

A particular form of Mermin's inequality is analyzed for repulsive inverse power potentials [V(r)=e ² r ^–m/m] in ad-dimensional space. For long-range potentials (m d) the system is put into a stabilizing background. Long-range order is shown to be excluded ford (m + 2)/2 whenm d, while for short-range potentials (m > d) we recover Mermin's result (d 2). For Coulomb systems (m=d – 2) and the experimentally studied electron surface layer (d = 2,m=1), long-range order cannot be excluded by the present argument.     

Influence of the Breit-Wigner type of instability on analytic properties of partial wave amplitudes

The relativistic binary processes are considered. For a general mass case the partial wave projection of an invariant amplitude involves some necessary continuation due to the appearance of the areas where the Mandelstam denominators vanish if the kinematical quantities have their physical values. To avoid the corresponding difficulties and to be able to perform practical and realistic calculations, the invariant amplitudes are expressed in terms of the exchanged stable and unstable objects and then they are projected onto the partial waves. In the present paper, their analytic properties in the complex energy squared plane are investigated in more detail. As the first approximation, the unstable objects are expressed in the Breit-Wigner form.     

Pseudopotential method for higher partial wave scattering

We present a zero-range pseudopotential applicable for all partial wave interactions between neutral atoms. For p and d waves, we derive effective pseudopotentials, which are useful for problems involving anisotropic external potentials. Finally, we consider two nontrivial applications of the p-wave pseudopotential: we solve analytically the problem of two interacting spin-polarized fermions confined in a harmonic trap, and we analyze the scattering of p-wave interacting particles in a quasi-two-dimensional system.     

The threshold behaviour of partial wave scattering amplitudes and theN/D-method

It is shown that in partial wave dispersion relations the weight function on the unphysical cut must have a certain number of zeros in order to permit the correct threshold behaviour of the amplitude. Assuming a solution — not necessarily with correct threshold behaviour — of the once-subtractedN/D-equations to exist, the role of the subtraction parameters in repeatedly subtractedN/D equations is studied with particular reference to the threshold behaviour.     

Scattering amplitudes for multi-indexed extensions of solvable potentials

New solvable one-dimensional quantum mechanical scattering problems are presented. They are obtained from known solvable potentials by multiple Darboux transformations in terms of virtual and pseudo virtual wavefunctions. The same method applied to confining potentials, e.g.  Pöschl–Teller and the radial oscillator potentials, has generated the multi-indexed Jacobi and Laguerre polynomials. Simple multi-indexed formulas are derived for the transmission and reflection amplitudes of several solvable potentials.     

Production representation of partial wave scattering amplitudes and the fo（600） particle

The establishlnent of production representation of partial wave scattering alnplitudes is reviewed in the context of quantum field theory. Its relation to the production representation, or Ning Hu representation in quantum mechanical scattering theory is pointed out. One of the most important application of the production representation is the physics of the fo（600） and K（700） scalar hadron resonances, on which we also give a brief review. It is emphasized that all evidences accunmlated so far are consistent with the picture that the fo（600） meson is the chiral partner of the Nambu Goldstone bosons in a linear realization of chiral symmetry.     

Scattering amplitudes for Coulomb plus rational separables-wave potentials

Zeitschrift für Physik A Hadrons and nuclei - The stationary scattering theory for infinite-range potentials introduced by Vesselova is applied to the Coulomb plus rationalN-term...     

New summation rules for coulomb wave functions

Sums of products of the Coulomb wave functions over degenerate manifolds have been obtained in a closed form. These sums appear in many atomic and molecular problems. The sums have been obtained making use of the properties of the Coulomb Green's function G(r, r('),E), in the limit E-->E(n), where E(n) is the eigenenergy of the hydrogenlike atomic ion. The closed Hostler-Pratt form of G in the coordinate representation has been used. The sums calculated are a consequence of the n degeneracy of the Coulomb atomic energy levels. This itself, as is well known, follows from the four-dimensional symmetry of the Coulomb problem for the hydrogen atom.     

Relativistic scattering theory for long-range potentials of the nonelectrostatic type

We define a modified free-time evolution for the Dirac equation with long-range potentials (1/|x|), where is the Dirac matrix, and prove a strong asymptotic completeness of the corresponding wave operators. Our methods also work for the magnetic fields ·A(x).     

On the partial wave method for self energy calculations for non-hydrogenic electrons

Abstract

A method for computing the self-energy correction for highly-ionized and high-Z many electron atoms is proposed and developed. The method is based on a partical wave analysis, and is immediately applicable to general potentials and many-electron wavefunctions.

In this work we discuss the general approach, develop a formalism amenable to practical anal- ysis, provide the angular momentum reduction for arbitrary one-electron orbitals, and describe the computation of the twdimensional integrals and their kernels required for the partial wave analysis. Analytical results allowing for a practical renormalization scheme are discussed.

This work is exploratory and developmental, and the present document provides a status report of our eforts. To date we have obtained numerical evidence that the method successfully handles the renormalization, and we report on significant progress in numerical methods for evaluating and approximating the two-dimensional integrals which occur in the method. We believe that this method can ultimately achieve an accuracy which is competitive with that of modern Brown's method calculations.

The methods discussed within this work for approximating the two-dimensional radial matrix eIements including the full retarded couIomb interaction can be applied to other relativistic atomic physics calculations as a practical way to obtain improvements over the coulomb and Breit approximations.     

Relations of loop partial amplitudes in gauge theory by Unitarity cut method

It is well known that under the color-decomposition, one-loop amplitude of gluons contains partial amplitudes of single and double trace structures, and particularly all partial amplitudes of double trace structure can be expressed as a linear combination of partial amplitudes of single trace structure. Using unitarity cut method, we prove that this result is the natural consequence of tree-level Kleiss-Kuijf relation. Generalizing the unitarity cut method to two-loop (triple cut in this case), we show that, unlike the one-loop case, partial amplitudes of double and triple trace structures cannot be expressed as a linear combination of partial amplitudes of leading-color single trace structure. For partial amplitudes of subleading-color single trace structure, we have shown a very non-trivial Kleiss-Kuijf relation for six and seven-point amplitudes, which is one new result of our paper and cannot be obtained by U(1)-decoupling method. Mysteriously, when we consider the case of eight points, Kleiss-Kuijf relation must be modified for subleading-color single trace partial amplitudes.