Speaker
Prof.
Antoni Szczurek
(Institute of Nuclear Physics PAN, Krakow and Rzeszow University, Rzeszow)
Description
We discuss a scenario in which the enhancement in the diphoton
final state at $M_{\gamma \gamma}$ = 750 GeV, recently observed
by the ATLAS and CMS collaborations, is a technipion. We consider two
different detailed minimal scenarios. In a first one
(vector-like technicolor model)
we assume that the vector-boson fusion is a dominant production mechanism.
In a second one (one family walking technicolor model) the technipion
is produced dominantly by the gluon-gluon fusion.
We adjust parameters of the model (coupling constant) to the size
of the signal at $\sqrt{s}$ = 13 TeV
and discuss the size of the signal at lower energies (LHC, Tevatron)
for $\gamma \gamma$ and jet-jet final states,
where it was not observed and check consistency with the existing data.
The signal is compared with the background diphoton contributions.
As background contributions we include $q \bar q$ annihilation,
gluon-gluon fusion via quark boxes, as well as
photon-photon fusion via lepton, quark and $W$-bosons boxes.
In the latter case (background) as well as for the technipion production
(signal) we include elastic-elastic, elastic-inelastic,
inelastic-elastic and inelastic-inelastic photon-photon processes,
where ``inelastic'' means associated e.m. dissociation of a proton.
In both cases we observe the dominance of inelastic-inelastic processes.
We consider also an alternative partonic approach with 2 $\to$ 3
subprocess (with off-shell photons) and compare it to the
approach with on shell photons.
We predict the signal cross section for purely exclusive
$p p \to p p \gamma \gamma$ procesess at $\sqrt{s}$ = 13 TeV
to be about 0.5 fb. Such a cross section would be measurable
with integrated luminosity about 20 fb$^{-1}$.
In all considered cases (other experiments) the signal is below
the background or/and below the threshold set by statistics
although some tension can be seen.
The presentation will be based on our upcoming paper [1].
[1] P. Lebiedowicz, M. {\L}uszczak, R. Pasechnik and A. Szczurek,
a paper in preparation.
Primary author
Prof.
Antoni Szczurek
(Institute of Nuclear Physics PAN, Krakow and Rzeszow University, Rzeszow)
Co-authors
Dr
Marta Luszczak
(Rzeszow University, Rzeszow)
Dr
Piotr Lebiedowicz
(Institute of Nuclear Physics PAN, Krakow)
Dr
Roman Pasechnik
(Lund University, Sweden)
