200 research outputs found
Nonlinear Bethe-Heitler pair creation with attosecond laser pulses at the LHC
The creation of lepton pairs ( and ) via multiphoton
absorption in collisions of ultrarelativistic ion beams with ultrashort
high-frequency laser pulses is considered. Both the free and the bound-free
production channels are addressed, where in the latter case the negatively
charged lepton is created in a bound atomic state. It is shown that these
nonlinear QED processes are observable when a table-top source of intense xuv
or x-ray laser radiation is operated in conjunction with the LHC. We discuss
the relative effectiveness of protons versus Pb ions and specify for each pair
production channel the most suitable collision system.Comment: 6 pages, 1 tabl
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic
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