Interpreting the 750 GeV diphoton signal as technipion

We discuss whether the enhancement in the diphoton final state at Mgg = 750 GeV, observed recently by the ATLAS and CMS Collaborations could be a neutral pseudoscalar technipion π∼0. We considered two distinct minimal models for the dynamical electroweak symmetry breaking. Here we concentrate only on two-flavor vector-like technicolor model and we assume that the two-photon fusion is a dominant production mechanism. We include contributions of 2 → 1, 2→2 and 2→3 partonic processes. All the mechanisms give similar contributions to the cross section. With the strong Yukawa (technipion-techniquark) coupling gTC ≃ 20 we roughly obtain the measured cross section of the "signal". With such value of gTC we get a relatively small total decay width Gtot. We discuss also the size of the signal at lower energies (LHC, Tevatron) for γ γ final states, where the enhancement was not observed. We predict a measurable cross section for neutral technipion production associated with one or two soft jets. The technipion signal is compared with the Standard Model diphoton background contributions. We observe the dominance of inelastic-inelastic γ γ processes. We predict the signal cross section for purely exclusive pp→ ppγ γ procesess at √s = 13 TeV to be about 0.2 fb. Such a cross section would be, however, difficult to measure with the planned integrated luminosity. We conclude that in all considered cases the signal is below the background or/and statistics is not sufficient to observe it.