31,202 research outputs found
OPE analysis of the nucleon scattering tensor including weak interaction and finite mass effects
We perform a systematic operator product expansion of the most general form
of the nucleon scattering tensor including electro-magnetic and
weak interaction processes. Finite quark masses are taken into account and a
number of higher-twist corrections are included. In this way we derive
relations between the lowest moments of all 14 structure functions and matrix
elements of local operators. Besides reproducing well-known results, new sum
rules for parity-violating polarized structure functions and new mass
correction terms are obtained.Comment: 50 pages, additional references adde
Fourier-transform spectroscopy of Sr2 and revised ground state potential
Precise potentials for the ground state X1Sigma+g and the minimum region of
the excited state 2_1Sigma+u of Sr2 are derived by high resolution
Fourier-transform spectroscopy of fluorescence progressions from single
frequency laser excitation of Sr2 produced in a heat pipe at 950 Celsius. A
change of the rotational assignment by four units compared to an earlier work
(G. Gerber, R. M\"oller, and H. Schneider, J. Chem. Phys. 81, 1538 (1984)) is
needed for a consistent description leading to a significant shift of the
potentials towards longer inter atomic distances. The huge amount of ground
state data derived for the three different isotopomers 88Sr2, 86Sr88Sr and
87Sr88Sr (almost 60% of all excisting bound rovibrational ground state levels
for the isotopomer 88Sr2) fixes this assignment undoubtedly. The presented
ground state potential is derived from the observed transitions for the radial
region from 4 to 11 A (9 cm-1 below the asymptote) and is extended to the longe
range region by the use of theoretical dispersion coefficients together with
already available photoassociation data. New estimations of the scattering
lengths for the complete set of isotopic combinations are derived by mass
scaling with the derived potential. The data set for the excited state
2_1Sigma+u was sufficient to derive a potential energy curve around the
minimum.Comment: 10 pages, 7 figures, some small corrections done especially to the
potential description of the excited state (already included in the published
journal version
On the Fourier transform of the characteristic functions of domains with -smooth boundary
We consider domains with -smooth boundary and
study the following question: when the Fourier transform of the
characteristic function belongs to ?Comment: added two references; added footnotes on pages 6 and 1
Adjointness Relations as a Criterion for Choosing an Inner Product
This is a contribution to the forthcoming book "Canonical Gravity: {}From
Classical to Quantum" edited by J. Ehlers and H. Friedrich. Ashtekar's
criterion for choosing an inner product in the quantisation of constrained
systems is discussed. An erroneous claim in a previous paper is corrected and a
cautionary example is presented.Comment: 6 pages, MPA-AR-94-
Diffractive charged meson pair production
We investigate the possibility to measure the nonforward gluon distribution
function by means of diffractively produced \pi^+\pi^- and K^+K^- pairs in
polarized lepton nucleon scattering. The resulting cross sections are small and
are dominated by the gluonic contribution. We find relatively large spin
asymmetries, both for \pi^+\pi^- and for K^+K^- pairs.Comment: 15 pages, version with changed kinematical cuts, to be pubished in
Phys.Lett.
Whitney coverings and the tent spaces for the Gaussian measure
We introduce a technique for handling Whitney decompositions in Gaussian
harmonic analysis and apply it to the study of Gaussian analogues of the
classical tent spaces of Coifman, Meyer and Stein.Comment: 13 pages, 1 figure. Revised version incorporating referee's comments.
To appear in Arkiv for Matemati
Empirical evidence for the Birch and Swinnerton-Dyer conjectures for modular jacobians of genus 2 curves
This paper provides empirical evidence for the Birch and Swinnerton-Dyer conjectures for modular Jacobians of genus 2 curves. The second of these conjectures relates six quantities associated to a Jacobian over the rational numbers. One of these six quantities is the size of the Shafarevich-Tate group. Unable to compute that, we computed the five other quantities and solved for the last one. In all 32 cases, the result is very close to an integer that is a power of 2. In addition, this power of 2 agrees with the size of the 2-torsion of the Shafarevich-Tate group, which we could compute
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