Conformal technicolor

Abstract

We point out that the flavor problem in theories with dynamical electroweak symmetry breaking can be effectively decoupled if the physics above the TeV scale is strongly conformal, and the electroweak order parameter has a scaling dimension d = 1 + ǫ with ǫ ≃ 1/few. There are many restrictions on small values of ǫ: for ǫ ≪ 1, electroweak symmetry breaking requires a finetuning similar to that of the standard model; large-N conformal field theories (including those obtained from the AdS/CFT correspondence) require fine-tuning for d < 2; 'walking technicolor' theories cannot have d < 2, according to gap equation analyses. However, strong small-N conformal field theories with ǫ ≃ 1/few avoid all these constraints, and can give rise to natural dynamical electroweak symmetry breaking with a top quark flavor scale of order 10 1/ǫ TeV, large enough to decouple flavor. Small-N theories also have an acceptably small Peskin-Takeuchi S parameter. This class of theories provides a new direction for dynamical electroweak symmetry breaking without problems from flavor or electroweak precision tests. A possible signal for these theories is a prominent scalar resonance below the TeV scale with couplings similar to a heavy standard model Higgs.

Warped electroweak breaking without custodial symmetry

“…3 we see that Higgs KK-modes are heavier than gauge boson ones, disfavoring its experimental detection at LHC. Moreover, as we have seen earlier in this Letter, there is a light Higgs eigenstate with wave function given by (24) and mass eigenvalue given by (26). After using the background metric A(y) in Eq.…”

“…[26], the main difference being that our proposal implies a strong deformation of the conformal theory in the IR. More details will be presented elsewhere [20].…”

Exploring T and S parameters in Vector Meson Dominance models of strong electroweak symmetry breaking

“…We thank J. Kamenik and O. Cata for discussions related to resolving discrepancies with their paper [41] (see notes 12,14,22), and to M. Frandsen for bringing [44] to our attention. This work was supported in part by the European Program "Unification in the LHC Era", contract PITN-GA-2009-237920 (UNILHC) and by the National Science Foundation under Grant No.…”

“…One possibility is that the UV theory stays close to a strongly interacting conformal fixed point over a wide range of energies, losing any connection to the weakly coupled description in the deep UV (if there was any) [10,11] 1 [12]. In this case, thinking in terms of gauge degrees of freedom may be misleading.…”

“…For a strongly coupled UV theory, like Walking [10,11] or Conformal [12] Technicolor, the dimension of Φ is in general unknown, except for the lower bound ∆ Φ > 1 as a consequence of unitarity. Interestingly, under the special assumption made in Conformal Technicolor (scalar bidoublet of dimension close to 1), one can also derive an upper bound…”