Footprints of New Strong Dynamics via Anomaly and the 750 GeV Diphoton

Abstract

The chiral anomaly provides smoking-gun evidence of a new confining gauge theory. Motivated by a reported event excess in a diphoton invariant mass distribution at the LHC, we discuss a scenario that a pseudo-Nambu-Goldstone (PNG) boson of a new QCD-like theory is produced by gluon fusion and decays into a pair of the standard model gauge bosons. Despite the strong dynamics, the production cross section and the decay widths are determined by an anomaly matching condition. The excess can be explained by the PNG boson with mass of around 750 GeV. The model also predicts exotic hadrons such as a color-octet scalar and baryons. Some of them are within the reach of the LHC experiment.

Toward a coherent solution of diphoton and flavor anomalies

“…The interpretation of the 750 GeV diphoton excess as due to a pNGB in this context has already been widely discussed in the literature [14][15][16][17][18][19][20][21][22][23], as well as in Composite Higgs [24][25][26][27][28] or Technicolor [29][30][31] setups. Particularly relevant to our setup is the extended discussion of such models presented in ref.…”

“…[14][15][16][17][18][19][20][21][22][23], we add a new non-abelian gauge interaction with symmetry group SU(N TC ) which confines at a scale Λ = O(1 TeV), and a set of elementary vectorlike fermions (denoted techni-quarks or TC quarks in the following) in the fundamental representation of this group and in some representations of the SM gauge group G SM . The number and type of SM representations define the number N F of independent techni-quarks, from the point of view of the new strong dynamics, and the corresponding approximate non-anomalous global symmetry G = SU(N F ) L × SU(N F ) R × U(1) V .…”

Constraints on color-octet companions of a 750 GeV heavy pion from dijet and photon plus jet resonance searches

“…If the excesses get confirmed by further data at Run 2 of the LHC, the 750 GeV resonance could be the first particle discovered beyond the Standard Model (SM). The relatively large cross-section of the signal suggests strong dynamics, possibly QCD-like, with its confinement scale at the TeV scale [3][4][5][6][7][8][9][10][11][12][13][14]. The 750 GeV resonance behaves in a similar manner to the neutral pion in the SM QCD sector.…”

“…In the many proposed composite models [3][4][5][6][7][8][9][10][11][12][13][14], the properties of the SM gauge singlet corresponding to the 750 GeV particle have been studied extensively, including related γZ, ZZ and W W decay channels. These models also predict color-octet and color-triplet bosons because the SM-singlet 750 GeV must couple to gluons.…”

The Higgs of the Higgs and the diphoton channel

“…The various models proposed in the literature [46,68,70,[92][93][94][95][96][97][98][99][100] employ massive techni-quarks, and a massive SM Higgs doublet. The masses are assumed to be comparable to the TC scale, but the coincidence is left unexplained.…”