We reexamine critically the chiral expansion for the baryon magnetic moments including the contributions from loops which involve intermediate octet and decuplet baryons. We find that, contrary to some claims, the nonanalytic loop contributions of orders m 1/2 s and m s ln m s are of the same general size because of large coupling factors for the latter, and that the decuplet contributions are as large as the octet contributions and must be included in a consistent calculation. There is no clear evidence of the convergence of the chiral series. The adequacy of the theory will not be established until dynamical models are able to calculate the contributions from the counterterms that largely hide the loop effects in fits to the data.
We recently derived explicit solutions of the leading-order Dokshitzer-Gribov-Lipatov-AltarelliParisi (DGLAP) equations for the Q 2 evolution of the singlet structure function Fs(x, Q 2 ) and the gluon distribution G(x, Q 2 ) using very efficient Laplace transform techniques. We apply our results here to a study of the HERA data on deep inelastic ep scattering as recently combined by the H1 and ZEUS groups. We use initial distributions F γp 2 (x, Q 2 0 ) and G(x, Q 2 0 ) determined for x < 0.1 by a global fit to the HERA data, and extended to x = 1 using the shapes of those distributions determined in the CTEQ6L and MSTW2008LO analyses from fits to other data. Our final results are insensitive at small x to the details of the extension. We obtain the singlet quark distribution Fs(x, Q 2 0 ) from F γp 2 (x, Q 2 0 ) using small non-singlet quark distributions taken from either the CTEQ6L or the MSTW2008LO analyses, evolve Fs and G to arbitrary Q 2 , and then convert the results to individual quark distributions. Finally, we show directly from a study of systematic trends in a comparison of the evolved F γp 2 (x, Q 2 ) with the HERA data, that the assumption of leading-order DGLAP evolution is inconsistent with those data.
We reexamine the unitarity constraints on the high-energy scattering of longitudinal W's and Z's and Higgs bosons in the standard model including one-loop corrections, and make an Argand-diagram analysis of the y ""0 scattering amplitudes. We find that the theory is approximately unitary and weakly interacting at OiX 2 ) for Higgs-boson couplings X X C . For X
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.