Dynamical clockwork axions

Abstract

Abstract:The clockwork mechanism is a novel method for generating a large separation between the dynamical scale and interaction scale of a theory. We demonstrate how the mechanism can arise from a sequence of strongly-coupled sectors. This framework avoids elementary scalar fields as well as ad hoc continuous global symmetries, both of which are subject to serious stability issues. The clockwork factor, q, is determined by the consistency of the strong dynamics. The preserved global U(1) of the clockwork appears as an accidental symmetry, resulting from discrete or U(1) gauge symmetries, and it is spontaneously broken by the chiral condensates. We apply such a dynamical clockwork to construct models with an effectively invisible QCD axion from TeV-scale strong dynamics. The axion couplings are determined by the localisation of the Standard Model interactions along the clockwork sequence. The TeV spectrum includes either coloured hadrons or vector-like quarks. Dark matter can be accounted for by the axion or the lightest neutral baryons, which are accidentally stable.

The clockwork supergravity

“…where 11) and V I are n V +1 arbitrary constants. The quantities a IJ , h I , h I x , T xyz , P 0 , and P x satisfy a number of constraints [23][24][25][26].…”

“…Some applications of the clockwork mechanism have been worked out in a series of recent papers [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

The minimal flavour violating axion

“…(2.12). Of particular interest is that the ratio between the axion coupling to photons and that to gluons, which is typically a free parameter [122][123][124][125][126][127], is exactly fixed to 8/3, as in the original DFSZ invisible axion model.…”

General continuum clockwork

“…We will see that this distinction is important when discussing continuum limit of the DCW. Here the suppressed coupling of the zero mode axion to the YM gauge fields at the N -th site is a consequence of the enlarged periodicity of [U(1) CW ] global in (2.6), which results in the enlarged field range of the zero mode axion 14) which is exponentially bigger than the original axion field range 2πf in (2.2). Another notable feature of the DCW is the spectrum of massive modes.…”

“…Among the many possible implementations of the mechanism [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], the CW axions [2,3] and U(1) gauge bosons [4,5] are particularly interesting as the key features of the mechanism can be understood in terms of a specific pattern of symmetry breaking of the underlying N + 1 (global or local) U(1) symmetries [U (1)] N +1 = N i=0 U(1) i , which is (explicitly or spontaneously) broken down to a U(1) CW subgroup. Furthermore, the key model parameters such as the CW parameter q and the involved axion-instanton couplings and U(1) gauge charges, are required to be integervalued (in appropriate units) by the compact [U (1)] N +1 , so the model has a built-in criterion for natural size of these model parameters.…”