Precision axion physics with running axion couplings

Abstract

We study the renormalization group running of axion couplings while taking into account that the Standard Model can be extended to its supersymmetric extension at a certain energy scale below the axion decay constant. We then apply our results to three different classes of axion models, i.e. KSVZ-like, DFSZ-like, and string-theoretic axions, and examine if string-theoretic axions can be distinguished from others by having a different pattern of low energy couplings to the photon, nucleons and electron. We find that the low energy couplings of string-theoretic axions have a similar pattern as those of KSVZ-like axions but yet reveal a sizable difference which might be testable in future axion search experiments. We also note that the coupling of KSVZ-like QCD axions to the electron is dominated by a three-loop contribution involving the exotic heavy quark, gluons, top quark and Higgs field.

Axion emission from supernova with axion-pion-nucleon contact interaction

“…and subsequently integrate out all massive fields heavier than µ = O(1) GeV, where q Φ is the PQ charge of Φ (in the normalization convention with q σ = 1) for the linearly 2 For string-theoretic axions that arise from the zero modes of higher-dimensional p-form gauge field, there is no UV completion with a linearly realized U(1) PQ . It has been noted that the tree-level values of C u,d for string-theoretic axions are of the order of α GUT /2π [36]. 3 Here for simplicity we ignore the effects of flavor mixings.…”

“…realized U(1) PQ , and ψ stands for all chiral fermions in the model. Then the axion-gluon coupling c G , which arises as a consequence of the axion-dependent field redefinition of ψ, corresponds to the coefficient of the U(1) PQ -SU(3) c -SU(3) c anomaly, while the couplings C u,d to the light quarks are determined by (i) a contribution from the axion-dependent fieldredefinition of {Q 1 , u c 1 , d c 1 }, (ii) the tree-level threshold correction from the axion mixing with the Z boson which is induced by the field redefinition of H u,d , and finally (iii) the radiative corrections caused by the gauge and Yukawa couplings in the model [36]. Putting these together, one finds [11,12], H u = (iσ 2 H d ) * and all SM fields are neutral under the linearly realized U(1) PQ , and therefore n u = n d = q Hu = q H d = 0.…”

“…where ∆C u,d are induced mostly by the axion-gluon coupling c G causing a running of C u,d over the scales from the mass of the exotic quark Q to µ = O(1) GeV [36]. On the other hand, the minimal DFSZ model [13,14] has n u = n d = 0, q Hu = q H d = −1 and all chiral fermions in the SM model have q ψ = 1/2, which result in and c G as an integer-valued additional free parameter, without specifying the underlying UV model.…”

Axion emission from supernova with axion-pion-nucleon contact interaction

“…Φ → e iq Φ a/fa Φ (Φ = ψ, H u,d ), (2.5) and subsequently integrate out all massive fields heavier than µ = O(1) GeV, where q Φ is the PQ charge of Φ (in the normalization convention with q σ = 1) for the linearly realized U (1) PQ , and ψ stands for all chiral fermions in the model. Then the axion-gluon coupling c G , which arises as a consequence of the axion-dependent field redefinition of ψ, corresponds to the coefficient of the U (1) PQ -SU (3) c -SU (3) c anomaly, while the couplings C u,d to the light quarks are determined by (i) a contribution from the axion-dependent fieldredefinition of {Q 1 , u c 1 , d c 1 }, (ii) the tree-level threshold correction from the axion mixing with the Z boson which is induced by the field redefinition of H u,d , and finally (iii) the radiative corrections caused by the gauge and Yukawa couplings in the model [33]. Putting these together, one finds…”

“…1 For string-theoretic axions that arise from the zero modes of higher-dimensional p-form gauge field, there is no UV completion with a linearly realized U (1)PQ. It has been noted that the tree-level values of C u,d for string-theoretic axions are of the order of αGUT/2π [33]. 2 Here for simplicity we ignore the effects of flavor mixings.…”