Automatic Peccei–Quinn symmetry

Abstract

We present a dynamical (composite) axion model where the Peccei-Quinn (PQ) symmetry arises automatically as a consequence of chirality and gauge symmetry. The Standard Model is simply extended by a confining and chiral SU (5) gauge symmetry. The PQ symmetry coincides with a B − L symmetry of the exotic sector. The theory is protected by construction from quantum gravitational corrections stemming from operators with mass dimension lower than nine.

A holographic perspective on the axion quality problem

“…If a similar mechanism were to occur for the underlying 4D gauge theory responsible for a composite axion, then our analysis suggests that the U (1) P Q global symmetry must be preserved up to at least dimension ten for an axion decay constant F a 10 9 GeV. A recent attempt to construct such a 4D model is given in [17], and other constructions with larger gauge groups should also be possible. In fact, our 5D framework can be used to model and give holographic descriptions of 4D strong dynamics with larger global symmetry groups or to consider more general possibilities with SM fermions propagating in the bulk.…”

“…Finally, in this class of models, the presence of SU (3) c as a 5D gauge symmetry in the bulk means that in the dual theory (some of) the fundamental constituents of the composite sector must be charged under QCD. This is analogous to 4D composite axion models considered in the literature [15][16][17]. Note that in our holographic description the operator dimension ∆ is a free parameter, since the underlying explicit 4D model is not specified.…”

“…Thus, Planck-suppressed operators which violate the U (1) P Q symmetry must be forbidden to sufficiently high order [7][8][9][10]. † Some of the possible ways to address this so-called axion quality problem include considering a composite axion [12,13] and realising the Peccei-Quinn symmetry as an accidental symmetry [14][15][16][17], gauging the Peccei-Quinn symmetry [18][19][20] or lowering the scale of spontaneous breaking which occurs in heavy axion models [21][22][23][24][25][26].…”

UV sensitivity of the axion mass from instantons in partially broken gauge groups

“…This possibility opens up new regions of the parameter space on the m 2 a , f a plane. Interesting models implementing the mechanism of [12] were proposed in [14][15][16][17][18], applications to models of inflation were studied in [19]. Other approaches to modify the axion mass within QCD were proposed in [20][21][22][23] while in [24][25][26][27][28][29][30] the axion mass is raised by coupling it to a new confining gauge group.…”

Unification of the standard model and dark matter sectors in [SU(5) × U(1)]4

“…The massless fermions may be identified as right-handed neutrinos[9]. See Ref [10]. for an application of a similar idea to the Peccei-Quinn mechanism.…”