5,014 research outputs found
Neutron electric form factor at large momentum transfer
Based on the recent, high precision data for elastic electron scattering from
protons and deuterons, at relatively large momentum transfer , we
determine the neutron electric form factor up to GeV. The values
obtained from the data (in the framework of the nonrelativistic impulse
approximation) are larger than commonly assumed and are in good agreement with
the Gari-Kr\"umpelmann parametrization of the nucleon electromagnetic form
factors.Comment: 11 pages 2 figure
On the measurement of quarkonium state in the processes and
The intermediate quarkonium state in electron-positron
annihilation to proton and antiproton as well as in antiproton-proton
annihilation to electron and positron can produce backward-forward asymmetry,
when populated through two photon exchange. We use the dispersion relation
method, which permits to express the asymmetry in terms of partial widths of
quarkonium decay. The asymmetry dependence on the center of mass energy in the
range near the resonance is presented. The comparison with a similar effect in
these reactions with the neutral -boson in the intermediate state is given.
We show that these effects are . The main source of asymmetry is
of pure QED origin () which arises from the interference between
initial and final state real photon emission
Comments on ISR method in modern experiment and influence of final state radiation
We study the effect of final state radiation in the process , in the kinematical conditions of BaBar and BESIII experiment. We show
that this effect could be large, in particular in the low region ( is
the photon energy fraction) and should be taken into account.Comment: 8 pages, 5 figure
Proton electron elastic scattering and the proton charge radius
It is suggested that proton elastic scattering on atomic electrons allows a
precise measurement of the proton charge radius. Very small values of
transferred momenta (up to four order of magnitude smaller than the ones
presently available) can be reached with high probability.Comment: 4 pages, 4 figure
Thermal properties of charge noise sources
Measurements of the temperature and bias dependence of Single Electron
Transistors (SETs) in a dilution refrigerator show that charge noise increases
linearly with refrigerator temperature above a voltage-dependent threshold
temperature, and that its low temperature saturation is due to SET
self-heating. We show further that the two-level fluctuators responsible for
charge noise are in strong thermal contact with the electrons in the SET, which
can be at a much higher temperature than the substrate. We suggest that the
noise is caused by electrons tunneling between the SET metal and nearby
potential wells
Towards a gauge-polyvalent Numerical Relativity code
The gauge polyvalence of a new numerical code is tested, both in
harmonic-coordinate simulations (gauge-waves testbed) and in
singularity-avoiding coordinates (simple Black-Hole simulations, either with or
without shift). The code is built upon an adjusted first-order
flux-conservative version of the Z4 formalism and a recently proposed family of
robust finite-difference high-resolution algorithms. An outstanding result is
the long-term evolution (up to 1000M) of a Black-Hole in normal coordinates
(zero shift) without excision.Comment: to appear in Physical Review
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