t-Channel couplings in Kaon-nucleon scattering

Hyperbolic dispersion relations are used to examine elasticKN and tintin1N amplitudes in the resonance region, and to extrapolate them to the annihilation channel. By evaluating the relations on a set of paths interior to the elastic channel physical regions, a spin separation oft-channel contributions is effected, and resonance couplings deduced. The results show clear evidence for effects attributable to exchanges withJ≦3, several of which have not previously been isolated. The special problems associated with the isoscalarS-wave states are discussed, and an estimate made of the ?-S ^* mixing angle.     

An application of dispersion relations to Kaon-nucleon scattering

In this paper we have made predictions for the invariant KN and $\text{K}$N scattering amplitudes in the kinematical region q_lab < 15 GeV/c and 0 >; t > -0.7 (GeV/c)².We have performed a direct fit to medium and high-energy data using a parametrization where the imaginary part of the amplitudes for energies above the phase-shift region is identical with the imaginary part of a Regge-pole amplitude, and the real part of the amplitudes has been obtained from a dispersion relation.The s-channel helicity amplitudes are compared with their counterparts in pion-nucleon scattering and other reactions. Exact exchange degeneracy can not be verified.Also the real part of the amplitudes are compared with the real part of phase-shift solutions. There is a qualitative agreement between these two real parts even though they differ in detail.     

Amplitude analysis of elastic pion-nucleus scattering

The complex amplitude of elastic pion-nucleus scattering is determined for ¹⁶O from the data of Albanese et al. and from other data at smaller angles and lower energies. The phase of the amplitude is extracted from the difference between π⁺ and π^? scattering. Zero trajectories and phase shifts are presented.     

Amplitude for N-gluon superstring scattering

We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope alpha'. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in alpha', for the so-called maximally helicity violating configurations, with N = 4, 5 and N = 6. We also obtain the leading O(alpha '2) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.     

The analysis of forward scattering channeling data

The use of large angle forward scattering offers the advantage of performing dechanneling measurements at low beam fluences in comparison to the backscattering technique. Here, we present the method for the analysis of forward scattering channeling data and discuss the advantages of the technique.     

A QCD analysis of diffractive deep-inelastic scattering data

We perform a novel type of analysis of diffractive deep-inelastic scattering data, in which the input parton distributions of the pomeron are parameterised using the perturbative QCD expressions. In particular, we treat individually the components of the pomeron of different size. We are able to describe simultaneously both the recent ZEUS and H1 diffractive data. In addition to the usual two-gluon model for the perturbative pomeron, we allow for the possibility that it may be made from two sea quarks.Received: 12 July 2004, Revised: 3 September 2004, Published online: 24 September 2004     

A new global analysis of deep inelastic scattering data

A new QCD analysis of deep inelastic scattering (DIS) data is presented. All available neutrino and antineutrino cross sections are reanalyzed and included in the fit, along with charged-lepton DIS and Drell–Yan data. A massive factorization scheme is used to describe the charm component of the structure functions. Next-to-leading-order parton distribution functions are provided. In particular, the strange-sea density is determined with a higher accuracy with respect to other global fits. Received: 16 March 1999 / Published online: 8 December 1999     

Kaon-nucleon finite energy sum rules revisited

Kaon-nucleon finite energy and continuous moment sum rule integrals are evaluated using recent phase-shift solutions to extract the t-channel exchange amplitudes and the results are compared with Regge pole models. The exchange degeneracy breaking previously observed in the ? and A₂ amplitudes is confirmed, and it is suggested that this may be due to an exotic P₀₁ KN resonance. Regge trajectories are extracted from the integrals and are in good agreement with those found from direct fits to high-energy data.     

Amplitude fluctuations in the theory of radio-wave refraction scattering

We consider some aspects of the theory of radio-wave scattering with respect to studies of radiation intensity fluctuations behind a random phase screen. The expressions for a piecewise approximation of the function of distribution of intensity fluctuations in the near zone and in the region of random focusing behind the screen are found. The expressions obtained are used to calculate the radio-wave scintillation index in these regions. The corresponding calculations are performed with allowance for the finite dimensions of external and internal scales of turbulent inhomogeneities of the phase screen. It is shown that the radio-wave refraction scattering, as a rule, is characterized by a pronounced random focusing of the radiation intensity behind the phase screen. However, under strongly developed turbulence of the radio-wave propagation medium (phase screen) the above phenomenon may be absent.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 9, pp. 1114–1124, September, 1996.This paper was supported by the Russian Foundation for Fundamental Research under project 95-02-03716.     

A global optical-model analysis of neutron elastic scattering data

Differential cross sections for neutron elastic scattering in the energy range 7–26 MeV from ⁴⁰Ca, ⁹⁰Zr, ⁹²Mo, ^{116, 124}Sn and ²⁰⁸Pb are analyzed in terms of a global optical-model potential. A smooth variation of the real radius parameters with mass number is investigated. Otherwise, optical-model geometrical parameters are kept fixed at values obtained by averaging individual best fits. The energy and isospin dependences of potential strengths and volume integrals per nucleon are presented.     

Light scattering data analysis for samples with large polydispersities

A simple method for analysing light scattering data for very polydisperse samples is presented. By eliminating the extrapolation procedure involved in the standard data analysis methods, it leads to more consistent results for the mean and variance of the size distribution.     

Amplitude correlations for inelastic proton scattering from44Ca

The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 53 5/2+ resonances in 45Sc. Although the reduced widths in each channel agree well with the Porter-Thomas distribution, large correlations are observed between widths and between amplitudes. The expected equality between the width correlation and the square of the amplitude correlation does not hold.     

Amplitude correlations for inelastic proton scattering from48Ti

The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 45 5/2⁺ resonances in⁴⁹V. The reduced widths in each channel follow a Porter-Thomas distribution, but extremely large amplitude correlations are observed — for one pair of channel amplitudes the relative sign is positive for 43 of 45 resonances. These results provide the first direct test of the Krieger-Porter reduced width amplitude distribution.     

An analysis of some proton-nucleus scattering data at 1 GeV

The elastic and inelastic scattering data of 1 GeV protons on ¹²C, ³⁹K,^{40, 48}Ca, ⁵⁸Ni and ²⁰⁸Pb are analysed within the framework of Glauber theory. The collective excitations to one-phonon levels are treated using the Tassie model under the adiabatic approximation. Effects of both the coupling between the elastic and the inelastic channels and the two-body correlation in the intrinsic state are considered. The ground state and transition densities for the protons are taken from electron scattering experiments and appropriate assumptions for the neutron densities are made. In most of the cases, better agreement with the experimental data than reported in earlier analyses is obtained. The effects of the coupling and the pair correlation seem to be important only for ¹²C. The elastic data strongly indicate that the density distributions for protons and neutrons in ⁴⁸Ca and ²⁰⁸Pb are different. In ⁴⁸Ca, the surface envelope of the neutron distribution is found to be the same as for the proton distribution but is placed at a larger radius. On the other hand, the neutron distribution in ²⁰⁸Pb seems to be relatively much more diffuse.     

Regge pole analysis of inelastic e - p scattering data

Based on the Regge pole fit to the high energy data on the e-p structure functions the q²-dependence of the Pomeranchuk and A₂ residues is determined in the non-scaling region. A FESR for vW₂ together with knowledge of these Regge residues is employed to confirm the existence of the J = 0 fixed pole in the virtual Compton amplitude.     

Overlap function analysis of p-p elastic scattering data at ISR energies

Recent data from the CERN-ISR are analysed in terms of a gaussian overlap function in impact parameter space. It is found that the upward concavity in the angular distributions is accurately reproduced. Phenomenological implications are discussed.     

NaNe potentials from a combined analysis of spectroscopic and scattering data

Experimental differential cross sections for the optical collision process Na(3s)+Ne+hν→Na(3p)+Ne and spectroscopic data for A²Π→X²Σ⁺optical transitions are used to obtain the potential curves for the X²Σ⁺ground and A²Π first excited states of the NaNe molecule and the spin-orbit function g_so(r).