P&A Colloquium

Effective field theory, factorization and renormalization: neutrino interactions, the Fermi function and more

Title:  Effective field theory, factorization and renormalization: neutrino interactions, the Fermi function and more
 
Abstract:  Precisely calculating differences between muon- and electron-neutrino interactions is difficult, but is vital for correctly interpreting neutrino oscillation experiments. I describe recent progress with powerful quantum field theory techniques to precisely determine the ratio of νe and νµ cross sections.  The beta decay Fermi function describes electron propagation in a nuclear Coulomb field, and accounts for QED radiative corrections that are enhanced at small electron velocity β or large nuclear charge Z.  Such enhanced corrections impact a variety of processes in and beyond the Standard Model, ranging from nuclear beta decay to dark matter annihilation signals.  I present the field theory factorization formula for the Fermi function and discuss implications for precision measurements. 
Date:
-
Location:
Chem-Phys 155

Organic Semiconductors: Opportunities (and Obstacles) to Technological Application

Organic light emitting diodes (OLEDs) were introduced into commercial application in the early 2000's and are now used regularly in phone screens and high-end TVs, while organic photovoltaics and transistors have not found the same technological success. In this talk, I will cover some of the fundamental performance and physical reasons that these devices are hindered while OLEDs flourish. Looking into the future beyond traditional electronics, I will discuss the unique physical properties of organic semiconductors that make them suitable for the development of spin-based devices and room temperature excitonic devices.

 

Host: Joe Brill

Date:
-
Location:
CP 155
Event Series:

On the validity of linear models of electron-lattice coupled systems

BCS theory and its strong-coupling extension have been widely successful in accounting for the properties of conventional superconductors, where phonons mediate pairing. These theoretical frameworks, however, neglect critical physical processes like the formation of competing phases or lattice polarons. This aspect has left several crucial questions in conventional superconductivity unanswered. For example, is there a maximum Tc for conventional superconductors? In this talk, I will discuss recent attempts to answer this question using numerically exact quantum Monte Carlo methods applied to the Holstein hamiltonian. I will show that many parameter regimes considered in the current literature violate the assumptions underlying this canonical toy model. These results remind us that we must be careful when using model hamiltonians to derive general conclusions about materials; however, they also direct us towards a wide-open are of research beyond BCS theory.

Host: Ambrose Seo

Date:
Location:
CP-155
Event Series:

Tabletop Tests of the Standard Model and Beyond: A Tale of Electron Dipole Moments

The Standard Model of Particle Physics (SM), our most fundamental mathematical description of physics reality, is the great triumph and the great frustration of modern physics.  The triumph is that the SM has survived all laboratory tests.  The frustration is that the SM is not consistent with basic features of the universe.  Tabletop measurements of electron dipole moments provide some of the most stringent tests of the SM and beyond. 

Host: Gardner and Korsch

Date:
Location:
CP 155
Event Series:

Majorana modes and their identification

We will introduce exotic particles like anyons and Majorana modes and describe
how they obey unfamiliar statistics which are neither like bosons nor like fermions. We will then discuss where one can expect to find such excitations. Finally, we will briefly explain our idea on how to distinguish Majorana modes from impostors.

 

Date:
Location:
CB 102
Event Series: