SEPTA meeting at Sussex (8 December 2021)

Wednesday 8 Dec 2021, 11:30 → 18:15 Europe/London

Shawcross AS1 (University of Sussex)

Andrea Banfi (University of Sussex), Jonas Lindert (University of Sussex)

This meeting brings together researchers of the SEPTA consortium, comprising members of the University of Sussex, RHUL and UCL. It is an opportunity to report on recent research highlights and discuss further directions.

The meeting will run in dual mode, i.e. in person and with Zoom links to be sent via email to all participants.

Zoom room of the meeting:
https://universityofsussex.zoom.us/j/99861220617

Meeting ID: 998 6122 0617
 

 

11:30 Welcome

1 Consortium meeting (faculty only)

https://universityofsussex.zoom.us/j/92451118818

13:00 Lunch

2 Introduction

https://universityofsussex.zoom.us/j/99861220617

First session of talks: Talks

3 Top quark mass corrections to NNLO double Higgs boson production

Speaker: Joshua Davies

slides.pdf

4 The graviton spectral function

Over the past decades, the asymptotic safety scenario has matured into a viable contender for a consistent theory of quantum gravity. However, the pressing question of unitarity is far from being settled. I will present important steps towards tackling this issue and show the first computation of the graviton spectral function in asymptotically safe quantum gravity. We find a positive graviton spectral function, showing a massless one-graviton peak and a multi-graviton continuum with an asymptotically safe scaling for large spectral values. For small spectral values, the correct effective field theory result is reproduced. I will indicate consequences for scattering amplitudes and unitarity.

Speaker: Manuel Reichert (University of Sussex)

Graviton-spectral.pdf

5 Massless Preheating and Electroweak Vacuum Metastability

Speaker: Jeff Kost (University of Sussex)

KOST_SEPTA.pdf

15:30 Coffee

Second session of talks: Talks

6 Searching for exotic physics in Tritium decay

Tritium Beta Decay is the least model dependent method for measuring the masses of neutrinos. It also provides a probe for Beyond the Standard Model effects such as sterile neutrinos and right-handed currents. This talk will give an overview of the expected standard model result and potential probes for these BSM effects.

Speaker: James Canning (UCL)

James Canning Sussex Beta Decay.pdf

James Canning Sussex Beta Decay.pptx

7 Mechanisms of neutrinoless double beta decay

Neutrinoless double beta (0νββ) decay is a hypothetical process of crucial interest due to its sensitivity both to the neutrino mass scale and to lepton-number violation. The precision of searches for the decay is largely constrained by disagreement between different many-body models for their nuclear matrix elements (NMEs), due in part to the large nuclei involved and the presence of correlated nucleon states. This talk will give an overview of two parallel strands of research: 1) a computational study of the impact of correlated NME errors on future 0νββ searches, via Bayesian methodologies; and 2) an analysis of corrections to a known leading-order contact contribution (in chiral EFT) to the 0νββ transition operator, including from the gluon vacuum condensate and from inelastic intermediate nuclear states.

Speaker: Graham Van Goffrier (University College London)

SEPTA Slides.pdf

8 Primordial black holes in a nutshell

Although black holes can be the remnants of dead stars, it is also possible that some are primordial. Such primordial black holes are the unique dark matter candidate which is not a new type of particle, and they could also explain some of the unexpected properties of the black hole mergers that LIGO and Virgo have detected. I will summarise the evidence and (fine-tuning) challenges behind this claim. There is interesting coincidence of scales between the LIGO-Virgo events, the Chandrasekhar limit and the horizon mass during the QCD transition in the early universe, and the wavelength of gravitational waves on which NANOGrav may (potentially) have detected a stochastic gravitational wave background.

Speaker: Christian Byrnes (University of Sussex (GB))

Byrnes-SEPTA-PBH-8Dec21.key

Byrnes-SEPTA-PBH-8Dec21.pdf

9 Discussion