[Jlab-seminars] Fwd: Physics Colloquium Friday, January 20, 2017

[Mary Fox]

-------- Forwarded Message --------
Subject: 	Physics Colloquium Friday, January 20, 2017
Date: 	Thu, 12 Jan 2017 21:51:06 +0000
From: 	Wilkinson, Eleonor V <evwilk at wm.edu>
To: 	physics0607 at physics.wm.edu <physics0607 at physics.wm.edu>
CC: 	undergrads0607 at physics.wm.edu <undergrads0607 at physics.wm.edu>



*_Colloquium_****_Randolf Pohl_ *[Host: T. Averett]**

Friday, January 20, 2017   Johannes Gutenberg-University Mainz, Germany 
and Max-Planck-Institute of Quantum Optics, Garching, Germany

4:00 PM *“/Shrinking the proton - Laser spectroscopy for nuclear physics 
and fundamental constants”/*

Small Hall, Room 111

*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)

*/*Cookies & coffee will be served in Room 122 at 3:30 PM/*

Elle Wilkinson

The College of William & Mary

Physics Admin/REU Coordinator

evwilk at wm.edu <mailto:evwilk at wm.edu>

757-221-3503

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