Speaker
Antoni Szczurek
(Institute of Nuclear Physics)
Description
We present differential cross sections for Higgs boson and/or
two-photon production from (virtual) Higgs boson within
the formalism of $k_t$-factorization. The off-shell $g^* g^* \to H$
matrix elements are used. We compare results obtained
with infinite top fermion (quark) mass and with finite mass
taken into account. The latter effect is rather small.
We compare results with different unintegrated gluon distributions.
Two methods are used. In the first method first Higgs boson is produced
in the $2 \to 1$ $g g \to H$ $k_t$-factorization
approach and then isotropic decay with the Standard Model branching
fraction is performed. In the second method we calculate directly
two photons coupled to the virtual Higgs boson. The results of the
two methods are compared and differences are discussed.
The leading order $g g \to H$ contribution is rather small compared
to the ATLAS experimental data
for all unintegrated gluon distributions.
We include also higher-order contribution
$g g \to H (\to \gamma \gamma) g$, $g g \to g H g$ and the contribution
of the $W^+ W^-$ and $Z^0 Z^0$.
The $gg\to Hg$ mechanism gives similar cross section as the $gg\to H$
mechanism.
We argue that there is almost no double counting when adding
$gg\to H$ and $gg\to Hg$ contributions due to different topology
of Feynman diagrams.
The final sum is comparable with the ATLAS two-photon data.
We discuss related uncertainties.
Author
Antoni Szczurek
(Institute of Nuclear Physics)
Co-authors
Marta Luszczak
(University of Rzeszow)
Rafal Maciula
(Institute of Nuclear Physics PAN)
