Particle Seminar: Tim Cohen (U. Oregon) “Stochastic Inflation at NNLO” Understanding the dynamics of light fields in a de Sitter (dS) spacetime is of both conceptual and phenomenological importance. To first approximation, a massless scalar field $\phi$ experiences quantum vacuum fluctuations sourced by the background geometry that manifest as Gaussian noise along with a restoring force due to the classical … Read More
Vector portal dark matter models, where dark matter couples to a dark photon that kinetically mixes with the visible photon, have become a widely-used benchmark for light sub-GeV dark matter in recent years. In particular, the regime where the dark photon mass is 1-2x the dark matter mass is characterized by a rich freezeout phenomenology, with three-body annihilation and kinematically … Read More
Abstract: Machine learning is increasingly becoming a powerful tool in particle physics. Despite significant computational advances, machine learning techniques are often blindly applied to data, with little consideration or understanding of the physics that is being exploited. In this talk, I will describe how thinking like a machine can lead to deep insights into fundamental problems in particle physics, focusing … Read More
Abstract: There are two canonical approaches to treating the Standard Model as an effective field theory: the Standard Model EFT (SMEFT), respecting the full electroweak gauge symmetry, and the Higgs EFT (HEFT), respecting only electromagnetism. Of these, SMEFT has become the predominant framework for interpreting LHC Higgs data and exploring the systematics of effective field theory. This raises a number of questions: Is … Read More
From: Markus A. Luty <markusluty@gmail.com>Date: Sat, 18 Sep 2021 at 20:12Subject: Re: Invitation to a Seminar to the LBL/Berkeley Theory GroupTo: Nadav Outmezguine <NJO@lbl.gov> Title: Hamiltonian Truncation and the Future of Numerical Quantum Field TheoryAbstract: Hamiltonian truncation is a non-perturbative approximation of a quantum system based on projecting the Hilbert space to a finite-dimensional subspace and numerically diagonalizing the Hamiltonian … Read More
The searches for particle Dark Matter (DM) have mostly focused on masses below 100TeV owing to the unitarity bound on thermal DM. In this talk, I will point out some intriguing dynamics in a confining dark sector that opens a vast parameter space beyond the unitarity bound. The key observation is the effect of the first order confinement phase transition … Read More
Title: Mass, Effective Operators and Locality in the Double Copy Abstract: The double copy is a web of relations between the scattering amplitudes of various quantum field theories. The original example was double-copying Yang-Mills to produce dilaton gravity. This was first discovered as the field theory limit of string theory KLT relations. In this limit, two features of the KLT … Read More
Toby Opferkuch (LBNL) Title: Detecting Muons in Neutron Stars with Neutrinos and Gravitational Waves Abstract: A large abundance of stable muons is an inescapable consequence of high-mass neutron stars. In this talk I will discuss the role of muon diffusion in neutron stars. This can lead to out-of-equilibrium muon decays yielding MeV-scale neutrinos as well as contribution to the neutron … Read More
Speaker: Peizhi Du (Stony Brook) Title: New backgrounds and new ideas for sub-GeV dark matter direct detection Abstract: Probing sub-GeV dark matter requires designing low threshold detectors and understanding backgrounds. In this talk I will address these two issues. First, we point out several unexplored low-energy backgrounds in sub-GeV dark matter searches, which arise from high-energy particles of cosmic or … Read More