8,123 research outputs found
A polarised QCD condensate: nu p elastic scattering as a probe of U_A(1) dynamics
U_A(1) dynamics have the potential to induce a polarised condensate inside a
nucleon. The formation of this condensate is related to the realisation of
U_A(1) symmetry breaking by tunneling processes such as instantons. If it is
present, the polarised condensate induces a term in g_1 which has support only
at x=0. Tunneling processes then induce a net transfer of ``spin'' from finite
x to x=0. The polarised condensate may be measured by comparing the
flavour-singlet axial charges which are extracted from polarised deep inelastic
and nu p elastic scattering experiments.Comment: 13 pages LaTeX, Section 3 improved to include discussion of the 3
flavour quark instanton interaction; to appear in Mod. Phys. Lett.
Gluon polarization in the proton
We combine heavy-quark renormalization group arguments with our understanding
of the nucleon's wavefunction to deduce a bound on the gluon polarization Delta
g in the proton. The bound is consistent with the values extracted from spin
experiments at COMPASS and RHIC.Comment: 4 page
The Spin and Flavour Dependence of High-Energy Photoabsorption
We review the present data on high-energy, spin-dependent photoabsorption. We
find a strong isotriplet term in which persists from
GeV to high polarised deep inelastic scattering. For
GeV and between 0.01 and 0.12 the isotriplet part of
behaves as , in contrast to soft Regge
theory which predicts that should converge as . The
isotriplet, polarised structure function is significantly
greater than the isotriplet, unpolarised structure function in
this kinematic region. We analyse the low photoabsorption data from E-143
and SMC and use this data to estimate the high-energy Regge contribution to the
Drell-Hearn-Gerasimov sum-rule.Comment: 19 pages, LaTeX, 3 figures generated as g1,g1F2 and A1.te
A New Hypothesis on the Origin of the Three Generations
We suggest that the Standard Model may undergo a supercritical transition
near the Landau scale, where the U(1) gauge boson couples to the left and right
handed states of any given fermion with different charges. This scenario
naturally gives rise to three generations of fermion, corresponding to the
three critical scales for the right-right, right-left and left-left fermion
interactions going supercritical, as well as CP violation in the quark sector.Comment: 12 pages, LaTeX, To appear in Mod.Phys.Lett.A (1996
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Low energy electron attachment to condensed formic acid
Dissociative electron attachment to formic acid in the condensed phase is studied using improved mass spectrometric detection of the negative ion fragments. The desorbed yields are measured as a function of incident electron energy in the range between 3 to 20 eV. Unlike previous work, the formation of the dehydrogenated anion HCOO? is observed and the signal to noise ratio is much higher for all other ions detected, i.e. OH?, O? and H?. Resonant structure seen in all anion yield functions, is attributed to dissociative electron attachment (DEA), whereas above 14 eV nonresonant dipolar dissociation (DD) dominates the desorption yields
Determination of the - mixing angle
We extract - mixing angle and the ratios of decay
constants of light pseudoscalar mesons , and using
recently available BaBar measurements on -photon and -photon
transition form factors and more accurate experimental data for the masses and
two-photon decay widths of the light pseduoscalar mesons.Comment: 5 pages, revtex, no figures, accepted for publication as a Brief
Report in Physical Review
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