89 research outputs found
Toward high-precision values of the self energy of non-S states in hydrogen and hydrogen-like ions
The method and status of a study to provide numerical, high-precision values
of the self-energy level shift in hydrogen and hydrogen-like ions is described.
Graphs of the self energy in hydrogen-like ions with nuclear charge number
between 20 and 110 are given for a large number of states. The self-energy is
the largest contribution of Quantum Electrodynamics (QED) to the energy levels
of these atomic systems. These results greatly expand the number of levels for
which the self energy is known with a controlled and high precision.
Applications include the adjustment of the Rydberg constant and atomic
calculations that take into account QED effects.Comment: Minor changes since previous versio
Finite nuclear size and Lamb shift of p-wave atomic states
We consider corrections to the Lamb shift of p-wave atomic states due to the
finite nuclear size (FNS). In other words, these are radiative corrections to
the atomic isotop shift related to FNS. It is shown that the structure of the
corrections is qualitatively different from that for s-wave states. The
perturbation theory expansion for the relative correction for a -state
starts from -term, while for -states it starts
from term. Here is the fine structure constant and is
the nuclear charge. In the present work we calculate the -terms for
-states, the result for -state reads
. Even more interesting are
-states. In this case the ``correction'' is by several orders of
magnitude larger than the ``leading'' FNS shift.Comment: 4 pages, 2 figure
Finite nuclear size effect on Lamb shift of s1/2, p1/2, and p3/2 atomic states
We consider one-loop self-energy and vacuum polarization radiative
corrections to the shift of atomic energy level due to finite nuclear size.
Analytic expressions for vacuum polarization corrections are derived. For the
self-energy of p1/2 and p3/2 states in addition to already known terms we
derive next-to-leading nonlogarithmic Z\alpha-terms. Together with
contributions obtained earlier the terms derived in the present work give
explicit analytic expressions for s1/2 and p1/2 corrections which agree with
results of previous numerical calculations up to Z=100 (Z is the nuclear charge
number). We also show that the finite nuclear size radiative correction for a
p3/2 state is not small compared to the similar correction for a p1/2 state at
least for small Z.Comment: 12 pages, 7 figure
QED theory of the nuclear recoil effect on the atomic g factor
The quantum electrodynamic theory of the nuclear recoil effect on the atomic
g factor to all orders in \alpha Z and to first order in m/M is formulated. The
complete \alpha Z-dependence formula for the recoil correction to the
bound-electron g factor in a hydrogenlike atom is derived. This formula is used
to calculate the recoil correction to the bound-electron g factor in the order
(\alpha Z)^2 m/M for an arbitrary state of a hydrogenlike atom.Comment: 17 page
Evaluation of the low-lying energy levels of two- and three-electron configurations for multi-charged ions
Accurate QED evaluations of the one- and two-photon interelectron interaction
for low lying two- and three-electron configurations for ions with nuclear
charge numbers are performed. The three-photon interaction is
also partly taken into account. The Coulomb gauge is employed. The results are
compared with available experimental data and with different calculations. A
detailed investigation of the behaviour of the energy levels of the
configurations , near
the crossing points Z=64 and Z=92 is carried out. The crossing points are
important for the future experimental search for parity nonconserving (PNC)
effects in highly charged ions
Two-Loop Effects and Current Status of the 4He+ Lamb Shift
We report on recent progress in the treatment of two-loop binding corrections
to the Lamb shift, with a special emphasis on S and P states. We use these and
other results in order to infer an updated theoretical value of the Lamb shift
in 4He+.Comment: 11 pages, nrc1 style; paper presented at PSAS (2006), Venic
Evaluation of the two-photon exchange diagrams for the electron configuration in Li-like ions
We present ab initio calculations of the complete gauge-invariant set of
two-photon exchange graphs for the electron configuration in
Li-like ions. These calculations are an important step towards the precise
theoretical determination of the - transition energy in the
framework of QED.Comment: 17 pages, 6 figure
Search for Possible Variation of the Fine Structure Constant
Determination of the fine structure constant alpha and search for its
possible variation are considered. We focus on a role of the fine structure
constant in modern physics and discuss precision tests of quantum
electrodynamics. Different methods of a search for possible variations of
fundamental constants are compared and those related to optical measurements
are considered in detail.Comment: An invited talk at HYPER symposium (Paris, 2002
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
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