Natural Electroweak Breaking from a Mirror Symmetry

Abstract

We present 'twin Higgs models', simple realizations of the Higgs as a pseudo-Goldstone boson that protect the weak scale from radiative corrections up to scales of order 5 -10 TeV. In the ultra-violet these theories have a discrete symmetry which interchanges each Standard Model particle with a corresponding particle which transforms under a twin or mirror Standard Model gauge group. In addition, the Higgs sector respects an approximate global symmetry. When this global symmetry is broken, the discrete symmetry tightly constrains the form of corrections to the pseudo-Goldstone Higgs potential, allowing natural electroweak symmetry breaking. Precision electroweak constraints are satisfied by construction. These models demonstrate that, contrary to the conventional wisdom, stabilizing the weak scale does not require new light particles charged under the Standard Model gauge groups.In the Standard Model (SM) the weak scale is unstable under quantum corrections. This suggests the existence of new physics at or close to a TeV that protects the Higgs mass parameter of the SM against radiative corrections. While the exact form that such new physics takes is unknown there are several interesting alternatives. One possibility, first proposed in [1,2] is that the Higgs is naturally light because it is the pseudo-Goldstone boson of an approximate global symmetry. This idea has recently experienced a revival in the form of little Higgs theories [3,4] (for a clear review and more references see [5]) that protect the Higgs mass from radiative corrections up to scales of order 5 -10 TeV.In this paper we propose a class of simple alternative realizations of the Higgs as a pseudo-Goldstone boson that also protect the weak scale from radiative corrections up to scales of order 5 -10

Effective theory of a light dilaton

“…In theories with a light Higgs, one class of promising solutions to the hierarchy problem are those where the SM Higgs emerges as the pseudo-Nambu-Goldstone boson of a global symmetry that is broken by strong dynamics [14][15][16]. This class of theories includes little Higgs models [17][18][19], and twin Higgs models [20,21]. If the ultraviolet physics involves strong conformal dynamics, the flavor scale can again be separated from the electroweak scale, allowing new contributions to flavor violating processes to be small enough to satisfy the existing constraints.…”

The little hierarchy in Universal Extra Dimensions

“…It was recently pointed out in that discrete symmetries could be used in addition to global symmetries, in order to forbid quadratic divergences from contributing to the Higgs mass [5,6,7]. We will consider a Twin Higgs model in one UED to see if this mechanism is effective in controlling the divergences arising in extra dimensional theories.…”

“…It is also particularly useful in going to a 5D theory, since the cutoff sensitivity is linear instead of logarithmic, as we have seen in the previous section. First, we review the relevant field content of the Twin Higgs Model [5] we are going to extend to the 5D bulk. The top quark Yukawa couplings have an approximate SU (6) × SU (4) × U (1) global symmetry, with the (SU (3) c × SU (2) × U (1)) A,B subgroups gauged.…”

“…[5] in UED. In the 4D model it is possible to eliminate the cutoff dependence coming from the top sector, by introducing extra fermions.…”

“…Several ideas along this line have been implemented in 4D in the last few years. Here we will implement a Little Higgs model [2,3,4] and a Twin Higgs model [5,6,7] in UED.…”