Interpreting the 750 GeV diphoton signal as technipion

Apr 13, 2016, 4:30 PM
SR4b (DESY Hamburg)


DESY Hamburg

Electroweak Physics and Beyond the Standard Model WG3 Electroweak Physics and Beyond the Standard Model


Prof. Antoni Szczurek (Institute of Nuclear Physics PAN, Krakow and Rzeszow University, Rzeszow)


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)


Dr Marta Luszczak (Rzeszow University, Rzeszow) Dr Piotr Lebiedowicz (Institute of Nuclear Physics PAN, Krakow) Dr Roman Pasechnik (Lund University, Sweden)

Presentation materials