1. E.C. AschenauerEIC INT Program, Seattle 2010 - Week 51

2. Precision Measurement of F L with the EIC E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 52 F L ~  s G(x,Q 2 ): the most “direct” way to G(x,Q 2 ) F L needs various √s  longer program In order to extract F L one needs at least two measurements of the inclusive cross section with a “wide” span in inelasticity parameter y (Q 2 =sxy) Coverage in x & Q 2 for inclusive cross section measurements Plots for 4 GeV electrons on 50 – 250 GeV protons

3. Measuring F L with the EIC E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 53 Conclusion from this study  Dominated by sys. uncertainties  gives max. luminosity  gives max. luminosity  here: 4fb -1 / A  here: 4fb -1 / A  Depending on x & Q 2 might be able to take a hit in luminosity able to take a hit in luminosity  need to include  need to include detector effects detector effects Lets get a feeling for systematic uncertainties 1% energy-to-energy normalization F L for fixed electron energy (4GeV) and proton energies: 50, 70, 100, 250 GeV Luminosity: 4fb -1 each setting

4. Measure g A (x) impact parameter dependent E.C. Aschenauer 4 Stringent requirements on:  Momentum resolution  t resolution and range EIC INT Program, Seattle 2010 - Week 5 A. Caldwell, H. Kowalski Phys.Rev.C81:025203,2010 Radiative Correction will impact them

5. Some Info on RadCors  Inclusive cross section   tot =  ela +  qela +  inel +  v for all parts photons can be radiated from the incoming and outgoing lepton, high Z-material Compton peak. radiation is proportional to Z 2 of target, like bremsstrahlung radiation is proportional to 1/m 2 of radiating particle  elastic:  quasi-elastic: scattering on proton of nuclei proton stays intact proton stays intact nuclei breaks up nuclei breaks up  two photon exchange? Interference terms? E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 55 initial final vacuum loops

6. Why are RadCor important?  Modify kinematics  Q 2 :  initial state: E’ beam = E beam – E  photon goes along the beam line  final state: E’ out = E out – E  photon goes somewhere in Calo  RadCor and detector smearing don’t factorize  need to have RadCor implemented in MC to unfold effects on kinematics  unfolding in bins N true =N meas -N bckg E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 56 events smeared into acceptance

7. RadCor and smearing unfolding in MC E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 57 generate observed kinematics x meas, Q 2 meas Radiative Correction Code photon radiated no photon radiated x true =x meas, Q 2 true =Q 2 meas calculate x true, Q 2 true hand kinematics to generator (lepto, pythia,..) What subprocess is generated is regulated by phase space Hand particles to GEANT

8. What do we know?  A lot of radiative correction codes for proton  much less existing for eA all experiments apart from HERMES had  -beams suppressed radiation HERMES uses modified version of RADGEN (hep-ph/9906408v1) Radiative corrections to deep inelastic scattering on heavy nuclei at HERA I. Akushevich and H. Spiesberger I. Akushevich and H. Spiesberger http://www.desy.de/~heraws96/proceedings/nuclei/Akushevich.ps.gz http://www.desy.de/~heraws96/proceedings/nuclei/Akushevich.ps.gz QED radiative processes in electron-heavy ion collisions at HERA K. Kurek K. Kurek http://www.desy.de/~heraws96/proceedings/nuclei/Kurek.ps.gz http://www.desy.de/~heraws96/proceedings/nuclei/Kurek.ps.gz E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 58

9. What do we know? E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 59  10 -4 < x < 10 -3 and 27.5 GeV x 410 GeV  solid: inelastic rad. corrections  dashed: inelastic, quasi-elastic and elastic rad. corrections Huge effects at high y PbSCHeD

10. What do we know? E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 510 Compton peak relevant if momentum transfer to nucleus very small effect of nuclear form factor included

11. What do we know? E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 511  Two photon exchange two photon exchange only important for very heavy nuclei

12. Can we suppress things?  elastic/quasi-elastic part: require some hadrons in detector  solid line: inelastic contribution  dashed line: after cuts E  > 10 GeV  E-p z from hadronic state is smaller E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 512 Need a code, which puts all together to make full calculations need to test analysis strategies to suppress rad. corrections SCHeD

13.  Djangoh  http://wwwthep.physik.uni- mainz.de/~hspiesb/djangoh/djangoh.html is compiled at BNL and running http://wwwthep.physik.uni- mainz.de/~hspiesb/djangoh/djangoh.html http://wwwthep.physik.uni- mainz.de/~hspiesb/djangoh/djangoh.html  eA part is included need to do more studies  HERACLES can be interfaced with other MC codes  HERMES code (RADGEN + eA version of lepto) is installed at BNL and close to run. No nuclear effects are included.  can compare results between eA-RADGEN with HERACLES  can nPDFs be included?  Hubert Spiesberger is coming to INT next week, juhu E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 513 and Summary

14. E.C. Aschenauer EIC INT Program, Seattle 2010 - Week 514 BACKUP