Speaker: Markus Luty
Title: Hamiltonian Truncation as Effective Field Theory
Room: 3024
Zoom: https://zoom.us/j/186024391
Host: Markus Luty
Abstract: Hamiltonian truncation is a variational approximation of a quantum system based on projecting the Hilbert space to a finite-dimensional subspace and numerically diagonalizing the resulting finite-dimensional Hamiltonian. This method has recently attracted renewed interest for applications to quantum field theory, but is much less developed than lattice quantum field theory. In this talk, I will describe the effective field theory of Hamiltonian truncation, which gives a systematic understanding of the errors made in the truncation and how to correct for them. The effective Hamiltonian has novel features such as non-Hermiticity and non-locality, both of which are controlled in a systematic expansion. Numerical results for 2D phi^4 theory show that the effective Hamiltonian reduces the errors in agreement with theoretical expectations.
User:
High-Energy Seminars
Time:
1:30pm - 3:00pm
Send Reminder:
Yes - 3 days 5 hour 0 minutes before start
Description:
Speaker: Gordan Krnjaic
Title: Towards a Realistic Model of Dark Atoms to Resolve the Hubble Tension
Room: 3024
Zoom: https://zoom.us/j/186024391
Host: Markus Luty
Abstract: It has recently been shown that a subdominant hidden sector of atomic dark matter in
the early universe can resolve the Hubble tension while maintaining good agreement
with most precision cosmological observables. However, such a solution requires a
hidden sector whose energy density ratios are the same as in our sector and whose
recombination also takes place at redshift z≈1100, which presents an apparent fine
tuning. We introduce a realistic model of this scenario that dynamically enforces these
coincidences without fine tuning. In our setup, the hidden sector contains an identical
copy of Standard Model (SM) fields, but has a smaller Higgs vacuum expectation
value (VEV) and a lower temperature. The baryon asymmetries and reheat
temperatures in both sectors arise from the decays of an Affleck-Dine scalar field,
whose branching ratios automatically ensure that the reheat temperature in each sector
is proportional to the corresponding Higgs VEV. The same setup also naturally ensures
that the Hydrogen binding energy in each sector is proportional to the corresponding
VEV, so the ratios of binding energy to temperature are approximately equal in the two
sectors. Furthermore, our scenario predicts a correlation between the SM/hidden
temperature ratio and the atomic dark matter abundance and automatically yields
values for these quantities that resolve the Hubble tension.
User:
High-Energy Seminars
Time:
1:30pm - 3:00pm
Send Reminder:
Yes - 3 days 5 hour 0 minutes before start
Description:
Speaker: LianTao Wang
Title: Signals of new dynamics during inflation
Room: 3024
Zoom: https://zoom.us/j/186024391
Host: Markus Luty
Abstract: Cosmological observations of signals from the inflation era offer a unique window into the dynamics at energy scales far beyond the reach of terrestrial experiments. I will discuss possible signals (including CMB, large-scale structure, and gravitational wave) associated with possible particle production and phase transition during the inflation.