[Jlab-seminars] Today's Physics Seminar: Melissa Cummings; "A Measurement of gp2 at Low Q2"

[Stephanie Tysor]

*Physics Seminar*

*Melissa Cummings*

*The College of William and Mary*

**

/"/A Measurement of g^p _2 at Low Q^2 /"/

*Abstract*

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 gp2 remains scarce. This talk will discuss the gp2 
experiment, which ran in Hall A at Jefferson Lab in the spring of 2012, 
and will provide the _rst measurement of gp2 in the resonance region; 
covering 0:02 < Q2 < 0:2 GeV2. The 0th 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 2nd moment allows for a 
benchmark test of _PT at low Q2. Specifcally, the behavior of the 
longitudinally-transverse spin polarizability (_LT ), as _PT 
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.

Monday, August 3, 2015

11:00am

CEBAF F113

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