Spring 2020

January 31, 2020 (Friday) 4:00-5:00p.m. Small Hall 111
Florian Hauenstein, ODU
J. Stevens
Pairing and Bonding of Nucleons in Nuclei
Protons and neutrons, known as nucleons, are bound together to make the nuclei of all
atoms. The usual and simple picture of this binding is an "effective" or average interac-
tion of one nucleon with all the other nucleons. This picture successfully describes most
scattering experiments where a projectile is scattered by a nucleus to reveal its inner struc-
ture. However, at short distances this simple effective interaction is not the full picture.
Indeed, some of the nucleons like to be paired together for a short time at short range, like
dancing partners during one song at a party. We call these pairs "Short Range Correla-
tions" (SRC) and they are being intensively investigated. These pairs play a crucial role
for a full understanding of the nucleus at short distances and in extreme conditions such
as neutron stars. Furthermore, nucleons in these SRC pairs appear to have significantly
different quark structure than free nucleons. In my talk, I will present our current picture
of nuclei and the SRC pairs within.

February 5, 2020 (Wednesday) 4:00-5:00p.m. Small Hall 111
Nadia Fomin, University of Tennessee
J. Dudek
The life and death of the free neutron
Abstract: Neutron beta decay is an archetype for all semi-leptonic charged-current weak processes. A precise value for the neutron lifetime is required for consistency tests of the Standard Model and is needed to predict the primordial 4He abundance from the theory of Big Bang Nucleosynthesis. Other parameters from neutron beta decay, in combination with the neutron lifetime, can be used to extract the Vud parameter in the quark mixing matrix of the Standard Model, providing a useful test of new physics.  These are all quantities that have been in flux in recent years, with the advent of high precision experiments.  The status of the field as well as recent and upcoming measurements will be presented. 

February 10, 2020 (Monday) 4:00-5:00p.m. Small Hall 111
Speaker: Julie Roche, Ohio University
Host: J. Stevens
Title: Tomography of the proton
Abstract: The proton is a composite particle made up of quark and gluon. The details of how gluons and quarks are confined within the proton remain surprisingly mysterious. For example, the elegant theory that governs the interaction of gluons and quarks, Quantum ChromoDynamics (QCD), cannot be solved analytically at the proton size scale. Experimentally, while the spatial distribution and the momentum distribution of quarks and gluons inside the proton are known, the correlation between the two is not. Generalized Parton Distributions (GPDs) were introduced in 1995. They encode this correlation.   In this talk, I will review the worldwide data of this emerging field of study. I will also emphasize the importance of the precision experimental approach implemented by my JLAB collaboration.

February 17, 2020 (Monday) 4:00-5:00p.m. Small Hall 111
Cristiano Fanelli, MIT/Jlab
J. Dudek
AI opportunities at JLab and EIC
Abstract: AI is all around us and if you searched on google this abstract you maybe unintentionally used it. 
With no surprise, AI is also entering in the field of particle and nuclear physics, where from the AI perspective, experimental and theoretical challenges often represent new opportunities.

In this talk I will give an overview of different activities at Jefferson Lab where AI can play a role to advance research. Jefferson Lab is a world-leading facility endowed with a continuous polarized beam designed to explore nuclear and hadron physics. It is currently taking data and has a wide approved program for the next years.  

AI will also be used in the future large scale intensity frontier experiments like the recently approved Electron Ion Collider, that will be built at Brookhaven National Laboratory in the next ten years in partnership with JLab. The EIC R&D program will likely be one of the first characterized by AI in the detector-design phase. 

For students considering a career in nuclear physics and interested in AI, this could be a timely decision...

February 19, 2020 (Wednesday) 4:00-5:00p.m. Small Hall 111
Speaker: Alexander Austregesilo, Carnegie Mellon University
Host: E. Tracy
Title: Understanding the Strong Interaction through Hadron Spectroscopy
Abstract: The strong interaction is the least understood of the four fundamental forces in nature, even though it is responsible for 99% of the mass of the visible universe as it binds the light quarks into hadrons like protons and neutrons. In recent years, advances in the theoretical description of the strong interaction and new methods for extracting the hadron spectrum from numerical simulations have greatly revived the interest in hadron spectroscopy. In addition, new experiments started to deliver high-precision data, often revealing unexpected signatures for states beyond the constituent quark model. As part of a global effort, the GlueX experiment at Jefferson Lab aims to study the light meson spectrum with an emphasis on the search for light hybrid mesons. Its unique selling point is a linearly-polarized 9 GeV photon beam that impinges on a liquid-hydrogen target contained within a hermetic detector with near-complete neutral- and charged-particle coverage. The experiment completed its first phase of data taking in 2018, and the quantity and precision of the data already exceed previous experiments for polarized photoproduction in this energy regime by orders of magnitude. A selection of early results is presented, focusing on the phenomenology of the production process with polarized photons. The potential to make significant contributions to the field of light-meson spectroscopy is demonstrated highlighting prominent examples. With significant upgrades to the detector, the upcoming second phase of GlueX will advance the exploration of the light meson spectrum with rare processes and final states with strange-quark content.

February 21, 2020 (Friday) 4:00-5:00p.m. Small Hall 111
Barry Sanders, OSA University of Calgary
I. Novikova
Learning for quantum control 
Abstract: We develop a framework that connects learning with classical and quantumcontrol, and this framework yields adaptive quantum-control policies that beat thestandard quantum limit, inspires new methods for improving quantum-gate design forquantum computing, and suggests new ways to apply classical and quantum machinelearning to control.  

February 24, 2020 (Monday) 4:00-5:00p.m. Small Hall 111
Boris Grube, Technical University of Munich
D. Armstrong
Searching for exotic forms of hadronic matter at the COMPASS experiment
Abstract: Quantum Chromodynamics (QCD) describes the interaction of quarks via the exchange of gluons. A remarkable feature of QCD is that also the gluons, i.e. the force mediators, carry the charges of the strong interaction and hence do self-interact. At low energies, this leads to the phenomenon of confinement, e.g. the entrapment of quarks and gluons into composite particles, the hadrons.

Although the QCD equations are simple to write down, they are very hard to solve in the confinement regime. A quantitative understanding of the phenomenon of confinement still poses considerable theoretical and experimental challenges and is one of the key issues in particle physics.

The study of the excitation spectrum of hadrons has provided essential clues that helped to develop QCD, but also still leaves a number of deep puzzles. In the constituent quark model, hadrons are either combinations of three quarks, which are called baryons, or quark-antiquark states, which are called mesons. However, QCD in principle allows for more complicated hadronic states like multi-quark states (e.g. molecule-like objects), states with excited gluonic fields (hybrids), or even purely gluonic bound states (glueballs).

The hunt for these so-called exotic hadrons is a world-wide experimental effort. The COMPASS experiment at CERN has collected world-leading datasets that allow us to study the spectrum of mesons that are composed of the three lightest quarks (up, down, and strange) with unprecedented detail and precision. I will present selected results from the analysis of these data with a focus on the search for exotic mesons.