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
James Hamlin, University of Florida
M. Qazilbash

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

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

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