PLANCK2024

Session

Parallel Session PII.1

6 Jun 2024, 14:30

IST, Lisboa

Conveners

Parallel Session PII.1

• Fabio Briscese

236. Ultra-high frequency GW backgrounds from cosmic strings

Peera Simakachorn (IFIC, Valencia U.)

06/06/2024, 14:30

This talk focuses on gravitational-wave backgrounds (GWB) from cosmic strings that would manifest only at ultra-high frequencies (above kilohertz), that leave no signal at either LIGO, Einstein Telescope, or LISA, and correspond to high-energy scale (beyond $10^{10}$ GeV) particle physics parameters. Signals from metastable local strings, with amplitude as large as the $\Delta N_{\rm eff}$...

241. Type II seesaw: vacuum stability, phase transitionsand gravitational waves

Aleksei Kubarski

06/06/2024, 14:50

Type II seesaw provides an attractive way to account for the observed light neutrino masses by adding a scalar triplet to the Standard Model. Due to a larger scalar sector, the vacuum structure of the model is richer and first-order phase transitions become available. We study (meta)stability of the electroweak vacuum, cosmic phase transitions and gravitational waves in the type II seesaw...

205. Dark linear seesaw mechanism

Aditya Batra (CFTP-IST, Lisbon)

06/06/2024, 15:10

I will discuss our recent paper Phys.Lett.B 843 (2023) 138012 where we propose a minimal model where a dark sector, odd under a Z2 discrete symmetry, is the seed of lepton number violation in the neutrino sector at the loop level, in the context of the linear seesaw mechanism. We study the dark-matter phenomenology of the model, focusing on the case in which the stable particle is the lightest...

242. Melting domain walls for Pulsar timing arrays

Rome Samanta

06/06/2024, 15:30

Based on: arxiv 2307.04582

We discuss cosmic domain walls described by a tension redshifting with the expansion of the Universe. These melting domain walls emit gravitational waves with the low-frequency spectral shape corresponding to the spectral index \gamma=3 favored by the recent Pulsar timing data. We discuss a concrete high-energy physics scenario leading to such a melting domain...

327. Model-independent constraints on the QCD axion from supernovae

Michael Stadlbauer

06/06/2024, 15:50

The QCD axion solves the strong CP problem and is one of the most searched for DM candidates. As of today, astrophysical observations, such as neutron star cooling and energy loss from supernovae, place the strongest bounds.
This bound generally depends on the specific QCD axion model under consideration. However, it also depends on couplings that are model-independent and still present when...