Spring 2017

January 20, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Randolf Pohl, Johannes Gutenberg-University Mainz, Germany and Max-Planck-Institute of Quantum Optics, Garching, Germany
Host: T. Averett
Title: Laser spectroscopy for nuclear physics and fundamental constants
Abstract: For more than a decade, the rms charge radius of the proton was known to be 0.88fm, with about 1% uncertainty [1]. Two methods, elastic electron scattering and precision laser spectroscopy of atomic hydrogen, yielded consistent values. In 2010, our result from laser spectroscopy of the exotic "muonic hydrogen" atom yielded a 4% smaller value, 0.84 fm, with an uncertainty of less than 0.1% [2,3]. In muonic hydrogen, a negative muon orbits a proton with a 200 times smaller Bohr orbit than in regular hydrogen, which increases the sensitivity of muonic hydrogen to the proton charge radius by 200^3 ~ 10 million! Since 2010, the discrepancy increased to more than 7 sigmas [4], making it one of the biggest discrepancies in the Standard Model. I will discuss the so-called "proton radius puzzle" [5], report on more measurements in muonic atoms [6], and the result of a new measurement in regular atomic hydrogen.


[1] P.J. Mohr et al. (CODATA 2006), Rev. Mod. Phys. 80, 633 (2008)
[2] Pohl et al. (CREMA coll.), Nature 466, 213 (2010)
[3] Antognini et al.,(CREMA coll.), Science 339, 417 (2013)
[4] Olive et al. (PDG 2014), Chin. Phys. C40, 090001 (2014)
[5] Pohl et al., Annu. Rev. Nucl. Part. Sci 63, 175 (2013)
[6] Pohl et al. (CREMA coll.), Science 353, 669 (2016)


February 17, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Marco Peloso, University of Minnesota
Host: M. Sher
Title: Particle physics signatures from inflation
Abstract: We will review motivations for cosmological inflation, and fundamental observables. We will then discuss signatures that can arise from the coupling of a pseudo-scalar inflaton to gauge fields. The coupling can naturally lead to a strong amplification of gauge modes, that can in turn source large density perturbations and gravitational waves, both at extra-galactic (thus affecting the Cosmic Microwave Background observations) and at interferometer scales (such as Advanced LIGO and LISA).

February 24, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker:
James Hamlin, University of Florida
Host:
M. Qazilbash
Title: 
Using applied pressure to squeeze new physics out of old materials
Abstract: There is an old piece of wisdom in condensed matter physics that new materials should always be subjected to measurements at low temperatures.  Improvements in high pressure technology have lead an increasing number of researchers to apply this old wisdom to another fundamental thermodynamic variable: pressure.  While lowering the temperature reveals the underlying quantum ground state, applying high pressure often induces the emergence of entirely new ground states.  In this talk I will provide an overview of experiments that we have performed using pressures that span the range from kilobars (the pressure at the bottom of the ocean) to megabars (the pressure at the core of the earth).  In particular, I will outline experiments aimed at understanding a new type of quantum phase transition, i.e., the transition between topologically trivial and non-trivial states of matter.  In addition, I will discuss the results of work we have performed that is motivated by two recent milestones in the history of high pressure science: The discovery of pressure induced superconductivity above 200 K in hydrogen sulfide and the metallization of hydrogen.

March 3, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Rajan Gupta
Host: K. Orginos
Title: In a world with 10 billion people, what will 8 billion do?
Abstract: Rapid advances in automation, robotization, computerization are changing local and global job markets. Worldwide, the youth are struggling to understand and define a meaningful role for themselves and a promising future for their families. While the future for the innovators, leaders and entrepreneurs is brighter than ever before, a large majority are becoming pessimistic and losing hope. This talk will examine existing trends and correlate many of the current challenges---jobs, poverty, population, migration, climate change, environmental degradation, etc.--- to ask the question, is liberal democracy under threat

March 31, 2017 (Friday) 4:00-5:00pm Small 111
Speaker: Ian Cloet, Argonne National Lab
Host: Mike Pennington
Title: Exploring the Multi-Dimensional Structure of HadronsArgonne National Laboratory
Abstract: Hadron physics has recently entered a new era, with the emergence of a comprehensive approach to the description of hadron structure, through the Wigner distributions of the fundamental constituents.  Wigner distributions are a quantum mechanical concept analogous to the classical notion of a phase space distribution and encode information on both the spatial and momentum tomography of a bound state. A simpler, precursor concept is that of hadron light-front wave functions. They have a probability interpretation and therefore provide a connection between dynamical properties of a quantum field theory and notions familiar from quantum mechanics. An important example is the pion's parton distribution amplitude (PDA), which is a critical piece of the explanation for the behaviour of this interesting hadron. This presentation will draw these threads together, tying the pion's PDA to real-world observables and statements about just when QCD might be perturbative. It will also illustrate the connection between Wigner distributions and transverse momentum dependent parton distribution functions (TMDs), and how light-front wave functions can be used to calculate TMDs for the pion, nucleon, and spin-one targets like the rho and deuteron.

April 7, 2017 (Friday) 4:00-5:00pm Small 111
Speaker: Michael Lubell, City College of CUNY
Host: Marc Sher
Title: SCIENCE UNDER THE POPULIST GUN
Abstract: For more than half a century science and technology have been the principal drivers of economic growth in the United States. Today, by some estimates they account for as much as 85 percent of the increase in the gross domestic product (GDP). But, while the nation as a whole has prospered economically, a majority of the population has benefitted only marginally. Wage gains have not kept pace with productivity growth, and for more than 15 years manufacturing jobs have suffered from technological displacement. Once thought to be immune to such pressures, service employment has also begun to reflect the march of technology. Automation, artificial intelligence and deep learning – all stemming from science – have the potential to play extraordinarily disruptive roles in the future labor force.

The 2010 election sparked the rise of the Tea Party, and the 2014 election transformed an upstart movement into much wider spread of populism. Donald Trump’s success in the 2016 general election and the unexpected strength of Bernie Sanders in the Democratic primary demonstrated the rapid growth of the movement. In reaching the White House, President Trump promised to bring back manufacturing jobs by rewriting trade pacts, imposing tariffs on imported goods and deregulating industry. He has also promised to bring back coal mining by loosening environmental restrictions. He is almost certain to fail in delivering on his jobs promises because his proposed fixes will pale in the face of accelerating technological impacts.

While extensive polling has shown that Americans continue to have warm feelings for science, the survey results also show that the support is shallow. If workers continue to feel the adverse effects of technology on the job market, there is a significant potential for a backlash against technology. The science community needs to prepare itself for that possibility by engaging with the public more effectively and helping social scientists and lawmakers to develop policies that mitigate the adverse impacts of technology on the American workforce.


April 14, 2017 (Friday) 4:00-5:00pm Small 111
Speaker: Vahagn Nazaryan
Host: Carl Carlson
Title:
Abstract: