1. University of Tennessee
Inclusive Scattering from Nuclei at x>1 and High Q2 with a 6 GeV Beam
E Analysis Update
Nadia Fomin
University of Tennessee
Hall C Users Group Meeting
January 22st, 2010

2. A long, long time ago….in Hall C
E ran in Fall 2004
Cryogenic Targets: H, 2H, 3He, 4He
Solid Targets: Be, C, Cu, Au.
Spectrometers: HMS and SOS (mostly HMS)

3. Introduction
Inclusive Scattering only the scattered electron is detected, cannot directly disentangle the contributions of different reaction mechanisms.
Inclusive Quasielastic and Inelastic Data allows the study of a wide variety of physics topics
Duality
Scaling (x, y, ξ, ψ)
Short Range Correlations – NN force
Momentum Distributions
Q2 –dependence of the F2 structure function

4. Introduction
Inclusive Scattering only the scattered electron is detected, cannot directly disentangle the contributions of different reaction mechanisms.
Inclusive Quasielastic and Inelastic Data allows the study of a wide variety of physics topics
Duality
Scaling (x, y, ξ, ψ)
Short Range Correlations – NN force
Momentum Distributions
Q2 –dependence of the F2 structure function
This talk: Focus on superfast quarks via ξ-scaling

5. However, the approach at finite Q2 will be different.
In the limit of high (ν,Q2), the structure functions simplify to functions of xbj, becoming independent of ν,Q2
2.5<Q2<7.4
2.5<Q2<7.4 Au
Jlab, Hall C, 2004
F2A
xbj ξ
As Q2 ∞, ξ x, so the scaling of structure functions should also be seen in ξ, if we look in the deep inelastic region.
However, the approach at finite Q2 will be different.
It’s been observed that in electron scattering from nuclei, the structure function F2, scales at the largest measured values of Q2 for all values of ξ

6. F2A for all settings and most nuclei for E02-019

7. ξ-scaling sure is pretty, but what does it mean?
Improved scaling with x ξ, but the implementation of TMCs leads to worse scaling by reintroducing the Q2 dependence
Rest of the talk deals only with carbon data

8. Can we get to SFQs? Yes we can! (Or so we think)
2 results for high x SFQ distributions (CCFR & BCDMS)
both fit F2 to exp(-sx), where s is the “slope” related to the SFQ distribution fall off.
CCFR: s=8.3±0.7 (Q2=125 GeV/c2)
BCMDS: s=16.5±0.5 (Q2: GeV/c2)
We can contribute something to the conversation if we can show that we’re truly in the scaling regime
Show that the Q2 dependence we see can be accounted for by TMCs and QCD evolution
Can’t have large higher twist contributions

9. CCFR
BCDMS

10. How do we get to SFQ distributions
We want F2(0), the massless limit structure function as well as it’s Q2 dependence
Schienbein et al, J.Phys, 2008

11. Iterative Approach Step 1 – obtain F2(0)(x,Q2)
Choose a data set that maximizes x-coverage as well as Q2
Fit an F2(0), neglecting g2 and h2 for the first pass
Use F2(0)-fit to go back, calculate and subtract g2,h2, refit F2(0), repeat until good agreement is achieved.
Step 2 – figure out QCD evolution of F2(0)
First naively tried using proton PDFs to map out the QCD evolution, but it didn’t work.

12. Iterative Approach
We do okay at Q2<10 Gev/C2 with QCD evolution based on proton PDFs, but cannot use it for any sort of global model
Solid black lines correspond to calculated F20, using above mentioned inadequate QCD evolution
E carbon
SLAC deuterium
CERN Carbon
BCDMS carbon

13. Iterative Approach Step 1 – obtain F2(0)(x,Q2)
Choose a data set that maximizes x-coverage as well as Q2
Fit an F2(0), neglecting g2 and h2 for the first pass
Use F2(0)-fit to go back, calculate and subtract g2,h2, refit F2(0), repeat until good agreement is achieved.
Step 2 – figure out QCD evolution of F2(0)
First naively tried using proton PDFs to map out the QCD evolution, but it didn’t work.
Fit the evolution of the existing data for fixed values of ξ (no good code exists for nuclear structure evolution, it seems)

14. Fit log(F20) vs log(Q2) for fixed values of ξ to
p2,p3 fixed
p1 governs the “slope”, or the QCD evolution.
fit p1 vs ξ Q2
Use the QCD evolution to redo the F20 fit at fixed Q2 and to add more data (specifically SLAC)

15. P1 parameter vs ξ, i.e. the QCD evolution
F20 fit with a subset of E and SLAC data

16. Putting it all Together
With all the tools in hand, we apply target mass corrections to the available data sets
With the exception of low Q2 quasielastic data – E data can be used for SFQ distributions
E carbon
SLAC deuterium
BCDMS carbon

17. Final step: fit exp(-sξ) to F20 and compare to BCDMS and CCFR
Fit region: 1.0 < ξ < 1.25
CCFR - (Q2=125 GeV/c2)
s=8.3±0.7
BCMDS – (Q2: GeV/c2)
s=16.5±0.5
s=14.31±0.17

18. Summary
Once we account for TMCs and extract F20 – we believe our data is in the scaling regime and can be compared to high Q2 results of previous experiments
appears to support BCDMS results
TO DO – finish analysis of other targets
see if the “s” slope varies with nuclei