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Techni-dilaton at 125 GeV

Shinya Matsuzaki, Koichi Yamawaki

TL;DR

The paper investigates whether a light techni-dilaton (TD) arising from walking technicolor can explain the LHC hints of a 125 GeV resonance. It analyzes the TD couplings, decay constants, and production mechanisms, deriving the key relation $g_{\rm TD}/g_{h_{\rm SM}} = \frac{(3-\gamma_m) v_{\rm EW}}{F_{\rm TD}}$ with $F_{\rm TD}$ linked to the trace anomaly via $F_{\rm TD}^2 M_{\rm TD}^2 = -4 \langle \theta_\mu^\mu\rangle$, and employs the one-family WTC framework with $N_{\rm TF} \simeq 4N_{\rm TC}$ to predict a TD near 125 GeV. The analysis shows enhanced gluon-fusion production and di-photon branching due to techni-quark loops, while other decay channels are comparatively suppressed, yielding a di-photon signal that can match or exceed SM Higgs expectations depending on $N_{\rm TC}$. The results suggest a distinctive TD signature: a growing $\gamma\gamma$ signal with little change in WW/ZZ channels as $N_{\rm TC}$ increases, offering a testable alternative to the SM Higgs in the 125 GeV region.

Abstract

Walking technicolor predicts a light composite scalar, techni-dilaton, arising as a pseudo Nambu-Goldstone boson for the approximate scale symmetry spontaneously broken by techni-fermion condensation. We show that a light techni-dilaton with mass of around 125 GeV can explain presently observed excesses particularly in the di-photon decay channel at LHC.

Techni-dilaton at 125 GeV

TL;DR

The paper investigates whether a light techni-dilaton (TD) arising from walking technicolor can explain the LHC hints of a 125 GeV resonance. It analyzes the TD couplings, decay constants, and production mechanisms, deriving the key relation with linked to the trace anomaly via , and employs the one-family WTC framework with to predict a TD near 125 GeV. The analysis shows enhanced gluon-fusion production and di-photon branching due to techni-quark loops, while other decay channels are comparatively suppressed, yielding a di-photon signal that can match or exceed SM Higgs expectations depending on . The results suggest a distinctive TD signature: a growing signal with little change in WW/ZZ channels as increases, offering a testable alternative to the SM Higgs in the 125 GeV region.

Abstract

Walking technicolor predicts a light composite scalar, techni-dilaton, arising as a pseudo Nambu-Goldstone boson for the approximate scale symmetry spontaneously broken by techni-fermion condensation. We show that a light techni-dilaton with mass of around 125 GeV can explain presently observed excesses particularly in the di-photon decay channel at LHC.

Paper Structure

This paper contains 4 sections, 7 equations, 2 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Techni-dilaton coupling
  3. The LHC signatures at 125 GeV
  4. Conclusion

Figures (2)

  • Figure 1: $g_{\rm TD}/g_{h_{\rm SM}}=(3-\gamma_m)v_{\rm EW}/F_{\rm TD}$ with $\gamma_m\simeq 1$, with respect to the TD mass $M_{\rm TD}$ in a range from 110 to 600 GeV for one-family models with $N_{\rm TF}=4 N_{\rm TC}$ fixed.
  • Figure 2: The TD LHC cross section at 7 TeV times branching ratios for $WW^*$ (top panel), $ZZ^*$ (middle panel) and di-photon (bottom panel) decay channels normalized to the corresponding quantities for the SM Higgs, in comparison with the current ATLAS (red curves) and CMS (blue curves) data WWZZdiphoton at 95% C.L.for the low Higgs mass range. The yellow band denotes the expected backgrounds within 2 $\sigma$ level.