Abstract
We try to interpret the 750 GeV diphoton excess in the Minimal Dilaton Model, which extends the SM by adding one linearized dilaton field and vector-like fermions. We first show by analytic formulae in this framework that the production rates of the $\gamma \gamma$, $gg$, $Z\gamma$, $ZZ$, $WW^\ast$, $t\bar{t}$ and $hh$ signals at the $750 {\rm GeV}$ resonance are only sensitive to the dilaton-Higgs mixing angle $\theta_S$ and the parameter $\eta \equiv v N_X/f$, where $f$ is the dilaton decay constant and $N_X$ denotes the number of the fermions. Then we scan the two parameters by considering various theoretical and experimental constraints to find the solutions to the diphoton excess. We conclude that the model can predict the central value of the diphoton rate without conflicting with any constraints. The signatures of our explanation at the LHC Run II and the vacuum stability at high energy scale are also discussed.
Highlights
The minimal dilaton model (MDM) extends the standard model (SM) by adding vector-like fermions and one gauge singlet scalar, which represents a linearized dilaton field
We tried to interpret the diphoton excess recently reported by the ATLAS and CMS collaborations at the 13- TeV LHC in the framework of the MDM
We first showed by analytic formulas that the production rates of the γ γ, gg, Z γ, Z Z, W W ∗, tt, and hh signals at the 750 GeV resonance are only sensitive to the dilaton– Higgs mixing angle θS and the parameter η ≡ v NX / f, where NX denotes the number of the vector-like fermions and f is the dilaton decay constant
Summary
More than 100 theoretical papers have appeared to interpret the excess in new physics models [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164], and most of them employed the process gg → S → γ γ with S denoting a scalar particle with mass around 750 GeV to fit the data. C (2016) 76:239 invariance can be naturally light in comparison with the high energy scale This model assumes that all SM particles except for the Higgs field do not interact with the dynamics sector, and the dilaton does not couple directly to the fermions and W , Z bosons in the SM. In this sense, the dilaton is equivalent to an electroweak gauge singlet field. The interactions between the dilaton and the photons/gluons are induced through loop diagrams of these fermions These features render the MDM a hopeful theory to explain the diphoton excess through the dilaton production.
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