PLANCK2024

Session

Parallel Session PI.2

4 Jun 2024, 14:30

Anfiteatro Abreu Faro (IST, Lisboa)

Conveners

Parallel Session PI.2

• João Penedo

256. Quadratic Coupling of Axions to Photons

Hoa Vuong (DESY)

04/06/2024, 14:30

Using chiral perturbation theory as a guideline, we show that the QCD axion couples to the electromagnetic (EM) kinetic term at one loop, generating a shift-breaking effective operator $a^2F_{\mu\nu}F^{\mu\nu}$. If axions make up dark matter, they induce some temporal variation of the EM-fine structure constant $\alpha$, which is severely constrained. Therefore, we can exploit the precision of...

258. Flavour-Invariant Contributions to the Strong CP Problem

Jonathan Kley (DESY)

04/06/2024, 14:50

Small instantons can increase the axion mass, due to an appropriate modification of QCD in the ultraviolet (UV), in a way where the axion still solves the strong CP problem. However, if any CP violation is present in UV theories which enhance small instantons, the minimum of the axion potential will be shifted, destroying the axion solution strong CP problem. In this talk, I will first...

240. ALP contribution to the Strong CP problem

Mr Victor Enguita Vileta

04/06/2024, 15:10

We compute the one-loop contribution to the $\bar{\theta}$-parameter of an axion-like particle (ALP) with CP-odd derivative couplings. Its contribution to the neutron electric dipole moment is shown to be orders of magnitude larger than that stemming from the one-loop ALP contributions to the up- and down-quark electric and chromoelectric dipole moments. This strongly improves existing bounds...

285. A Minimal Solution to the Strong CP Problem

Claudio Andrea Manzari (UC Berkeley & LBNL)

04/06/2024, 15:30

I propose a solution to the Strong CP problem, based on an underlying CP symmetry and a flavor symmetry. Requiring the Standard Model to have more than one Higgs doublet and softly breaking CP and the flavor symmetry only in the scalar sector, allows to recover the CP violating phase in the quark mass matrix without generating a large strong CP angle. I show that this conclusion holds at...

208. Axion paradigm with "coloured" neutrino masses

Henrique Brito Câmara (CFTP/IST, U. Lisboa)

04/06/2024, 15:50

I will discuss our recent paper Phys.Rev.Lett. 132 (2024) 5, 051801, where we propose a generalized KSVZ-type axion framework in which coloured fermions and scalars act as two-loop Majorana neutrino-mass mediators. The global Peccei-Quinn symmetry under which exotic fermions are charged solves the strong CP problem. Within our general proposal, various setups can be distinguished by probing...