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:
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April 7, 2017 (Friday) 4:00-5:00pm Small 111
Speaker: Michael Lubell, City College of CUNY
Host: Marc Sher
Title:
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April 14, 2017 (Friday) 4:00-5:00pm Small 111
Speaker: Vahagn Nazaryan
Host: Carl Carlson
Title:
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