Medium Energy Physics Seminar

Conference Room Rm B-221, Building 203,
Argonne National Laboratory
at 10:00 AM

Melissa Cummings
William and Mary
A Measurement of g^p₂ at Low Q²
Host: Roy Holt
2 July 2015

Jefferson Lab has been at the forefront of a program to study the polarized structure of nucleons. Measurements of the spin dependent structure functions, g₁ and g₂, have proven to be powerful tools in testing and understanding QCD. The neutron structure function gⁿ₂ has been measured extensively in Hall A at Jefferson Lab over a wide range of Q², but data for g^p₂ remains scarce. This talk will discuss the g^p₂experiment, which ran in Hall A at Jefferson Lab in the spring of 2012, and will provide the first measurement of g^p₂ in the resonance region; covering 0.02 < Q² < 0.2 GeV². The 0^th moment of g₂ provides a test of the Burkhardt-Cottingham sum rule, which states that the integral of g₂ over the Bjorken scaling variable x goes to zero. This sum rule, valid for all values of Q², has been satisfied for the neutron, but a violation is suggested for the proton at high Q². The 2^nd moment allows for a benchmark test of χPT at low Q². Specifically, the behavior of the longitudinally-transverse spin polarizability (δ_LT), as χPT calculations of this quantity deviate significantly from the measured neutron data. This talk will discuss the current status of the analysis along with preliminary results.

Kawtar Hafidi, Chairwoman (+1-630-252-4012, [email protected])

Debbie Beres, Secretary (+1-630-252-4100, [email protected] )

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Paul E. Reimer
[email protected]
1 July 2015