85 research outputs found
On the light quark mass effects in Higgs boson production in gluon fusion
Production of Higgs bosons at the LHC is affected by the contribution of
light quarks, that mediate the gg \to Hg transition. Although their impact is
suppressed by small Yukawa couplings, it is enhanced by large logarithms of the
ratio of the Higgs boson mass or its transverse momentum to light quark masses.
We study the origin of this enhancement, focusing on the abelian corrections to
gg \to Hg amplitudes of the form (C_F alphas L^{2})^n, where $L \in {
ln(s/mb^2), ln(p_\perp^2/mb^2) }. We show how these non-Sudakov double
logarithmic terms can be resummed to all orders in the strong coupling
constant. Interestingly, we find that the transverse momentum dependence of
these corrections is very weak due to a peculiar cancellation between different
logarithmic terms. Although the abelian part of QCD corrections is not expected
to be dominant, it can be used to estimate missing higher-order corrections to
light quark contributions to Higgs boson production at the LHC.Comment: 18 pages, 2 figure
Bottom Quark Mass from Sum Rules to
We use the approximation of the heavy-quark vacuum
polarization function in the threshold region to determine the bottom quark
mass from nonrelativistic sum rules. We find very good stability and
convergence of the perturbative series for the bottom quark mass in
renormalization scheme. Our final result is
.Comment: 23 pages, 6 figures, journal versio
Three-loop quark form factor at high energy: the leading mass corrections
We compute the leading mass corrections to the high-energy behavior of the
massive quark vector form factor to three loops in QCD in the
double-logarithmic approximation.Comment: 9 pages, 10 figures, LaTe
Light Quark Mediated Higgs Boson Threshold Production in the Next-to-Leading Logarithmic Approximation
We study the amplitude of the Higgs boson production in gluon fusion mediated
by a light quark loop and evaluate the logarithmically enhanced radiative
corrections to the next-to-leading logarithmic approximation which sums up the
terms of the form to all orders in the strong
coupling constant. This result is used for the calculation of the process cross
section near the production threshold and gives a quantitative estimate of the
three and four-loop bottom quark contribution to the Higgs boson production at
the Large Hadron Collider.Comment: 25 pages, 6 figure
Hyperfine splitting in positronium to : one-photon annihilation contribution
We present the complete result for the one-photon
annihilation contribution to the hyperfine splitting of the ground state energy
levels in positronium. Numerically it increases the prediction of quantum
electrodynamics by kHz.Comment: 5 pages, 2 figure
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