359 research outputs found
Corrections to deuterium hyperfine structure due to deuteron excitations
We consider the corrections to deuterium hyperfine structure originating from
the two-photon exchange between electron and deuteron, with the deuteron
excitations in the intermediate states. In particular, the motion of the two
intermediate nucleons as a whole is taken into account. The problem is solved
in the zero-range approximation. The result is in good agreement with the
experimental value of the deuterium hyperfine splitting.Comment: 7 pages, LaTe
Comparison of Isoscalar Vector Meson Production Cross Sections in Proton-Proton Collisions
The reaction was investigated with the TOF
spectrometer, which is an external experiment at the accelerator COSY
(Forschungszentrum J\"ulich, Germany). Total as well as differential cross
sections were determined at an excess energy of (). Using the total cross section of for the
reaction determined here and existing data for the reaction
, the ratio
turns out to be
significantly larger than expected by the Okubo-Zweig-Iizuka (OZI) rule. The
uncertainty of this ratio is considerably smaller than in previous
determinations. The differential distributions show that the
production is still dominated by S-wave production at this excess energy,
however higher partial waves clearly contribute. A comparison of the measured
angular distributions for production to published distributions for
production at shows that the data are consistent with an
identical production mechanism for both vector mesons
Strong rescattering in K-> 3pi decays and low-energy meson dynamics
We present a consistent analysis of final state interactions in
decays in the framework of Chiral Perturbation Theory.
The result is that the kinematical dependence of the rescattering phases cannot
be neglected. The possibility of extracting the phase shifts from future
interference experiments is also analyzed.Comment: 14 pages in RevTex, 3 figures in postscrip
Nuclear structure corrections in the energy spectra of electronic and muonic deuterium
The one-loop nuclear structure corrections of order (Z alpha)^5 to the Lamb
shift and hyperfine splitting of the deuterium are calculated. The contribution
of the deuteron structure effects to the isotope shift (ep)-(ed), (mu p)-(mu d)
in the interval (1S - 2S) is obtained on the basis of modern experimental data
on the deuteron electromagnetic form factors. The comparison with the similar
contributions to the Lamb shift for electronic and muonic hydrogen shows, that
the relative contribution due to the nucleus structure increases when passing
from the hydrogen to the deuterium.Comment: Talk presented at the Conference "Physics of Fundamental
Interactions" of the Nuclear Physics Section of the Physics Department of
RAS, ITEP, Moscow, 2-6 December, 2002; 8 pages, REVTE
Muonic hydrogen ground state hyperfine splitting
Corrections of orders alpha^5, alpha^6 are calculated in the hyperfine
splitting of the muonic hydrogen ground state. The nuclear structure effects
are taken into account in the one- and two-loop Feynman amplitudes by means of
the proton electromagnetic form factors. The modification of the hyperfine
splitting part of the Breit potential due to the electron vacuum polarization
is considered. Total numerical value of the 1S state hyperfine splitting
182.638 meV in the (mu p) can play the role of proper estimation for the
corresponding experiment with the accuracy 30 ppm.Comment: 18 pages, Talk presented at the 11th Lomonosov Conference on
Elementary Particle Physics, Moscow State University, August 200
Theory of muonic hydrogen - muonic deuterium isotope shift
We calculate the corrections of orders alpha^3, alpha^4 and alpha^5 to the
Lamb shift of the 1S and 2S energy levels of muonic hydrogen (mu p) and muonic
deuterium (mu d). The nuclear structure effects are taken into account in terms
of the proton r_p and deuteron r_d charge radii for the one-photon interaction
and by means of the proton and deuteron electromagnetic form factors in the
case of one-loop amplitudes. The obtained numerical value of the isotope shift
(mu d) - (mu p) for the splitting (1S-2S) 101003.3495 meV can be considered as
a reliable estimation for corresponding experiment with the accuracy 10^{-6}.
The fine structure interval E(1S)-8E(2S) in muonic hydrogen and muonic
deuterium are calculated.Comment: 22 pages, 7 figure
Spin density matrix of the ω in the reaction p¯p→ωπ0
The spin density matrix of the ω has been determined for the reaction p¯p→ωπ0 with unpolarized in-flight data measured by the Crystal Barrel LEAR experiment at CERN. The two main decay modes of the ω into π0γ and π+π-π0 have been separately analyzed for various p¯ momenta between 600 and 1940 MeV/c. The results obtained with the usual method by extracting the matrix elements via the ω decay angular distributions and with the more sophisticated method via a full partial wave analysis are in good agreement. A strong spin alignment of the ω is clearly visible in this energy regime and all individual spin density matrix elements exhibit an oscillatory dependence on the production angle. In addition, the largest contributing orbital angular momentum of the p¯p system has been identified for the different beam momenta. It increases from Lp¯pmax = 2 at 600 MeV/c to Lp¯pmax = 5 at 1940 MeV/c
Proton Zemach radius from measurements of the hyperfine splitting of hydrogen and muonic hydrogen
While measurements of the hyperfine structure of hydrogen-like atoms are
traditionally regarded as test of bound-state QED, we assume that theoretical
QED predictions are accurate and discuss the information about the
electromagnetic structure of protons that could be extracted from the
experimental values of the ground state hyperfine splitting in hydrogen and
muonic hydrogen. Using recent theoretical results on the proton polarizability
effects and the experimental hydrogen hyperfine splitting we obtain for the
Zemach radius of the proton the value 1.040(16) fm. We compare it to the
various theoretical estimates the uncertainty of which is shown to be larger
that 0.016 fm. This point of view gives quite convincing arguments in support
of projects to measure the hyperfine splitting of muonic hydrogen.Comment: Submitted to Phys. Rev.
Higher-Order Nuclear-Polarizability Corrections in Atomic Hydrogen
Nuclear-polarizability corrections that go beyond unretarded-dipole
approximation are calculated analytically for hydrogenic (atomic) S-states.
These retardation corrections are evaluated numerically for deuterium and
contribute -0.68 kHz, for a total polarization correction of 18.58(7) kHz. Our
results are in agreement with one previous numerical calculation, and the
retardation corrections completely account for the difference between two
previous calculations. The uncertainty in the deuterium polarizability
correction is substantially reduced. At the level of 0.01 kHz for deuterium,
only three primary nuclear observables contribute: the electric polarizability,
, the paramagnetic susceptibility, , and the third Zemach
moment, . Cartesian multipole decomposition of the virtual
Compton amplitude and its concomitant gauge sum rules are used in the analysis.Comment: 26 pages, latex, 1 figure -- Submitted to Phys. Rev. C -- epsfig.sty
require
- …