Asking for an extra photon in Higgs production at the LHC and beyond
Emidio Gabrielli, Barbara Mele, Fulvio Piccinini, Roberto Pittau
Abstract
We study the inclusive production of a Higgs boson in association with a high-
p
T
photon at the LHC, detailing the leading-order features of the main processes contributing to the
Hγ
final state. Requiring an extra hard photon in Higgs production upsets the cross-section hierarchy for the dominant channels. The
Hγ
inclusive production comes mainly from photons radiated in vector-boson fusion (VBF), which accounts for about 2/3 of the total rate, for
p
γ,j
T
>30
GeV, at leading order. On the other hand, radiating a high-
p
T
photon in the main top-loop Higgs channel implies an extra parton in the final state, which suppresses the production rate by a further
α
S
power. As a result, the
Hγ
production via top loops at the LHC has rates comparable with the ones arising from either the
Ht
t
¯
production or the
HW(Z)γ
associated production. Then, in order of decreasing cross section, comes the single-top-plus-Higgs channel, followed in turn by the heavy-flavor fusion processes
b
b
¯
→Hγ
and
c
c
¯
→Hγ
. The
Hγ
production via electroweak loops has just a minor role. At larger c.m. energies, the
Ht
t
¯
γ
channel surpasses the total contribution of top-loop processes. In particular, requiring
p
γ,j
T
>30
GeV at
S
−
−
√
≃100
TeV,
Ht
t
¯
γ
accounts for about
1/4
of the inclusive
Hγ
production at leading order, about half of the total being due to VBF production.