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Radiative Corrections for Heavy Nuclei. Precision Measurement of F L with the EIC. F L ~ a 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 - PowerPoint PPT Presentation
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Precision Measurement of FPrecision Measurement of FLL with the EIC with the EIC
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 22
d2 empNC
dxdQ22em
2 YxQ4
(F2 y2
YFL Y
YxF3)
FFL L ~ ~ ssG(x,QG(x,Q22): the most “direct” way to G(x,Q): the most “direct” way to G(x,Q22))
FFLL needs various needs various √s√s longer programlonger program
In order to extract FIn order to extract FLL one needs one needsat least two measurements at least two measurements of theof theinclusive cross section with a inclusive cross section with a ““wide” span in inelasticity wide” span in inelasticity parameter parameter yy (Q (Q22=sxy)=sxy)
Coverage in x & QCoverage in x & Q2 2 for inclusivefor inclusivecross section measurements cross section measurements
Plots for 4 GeV electrons on Plots for 4 GeV electrons on 50 – 250 GeV protons50 – 250 GeV protons
Measuring FMeasuring FLL with the EIC with the EIC
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 33
Conclusion from this studyConclusion from this study Dominated by sys. uncertaintiesDominated by sys. uncertainties gives max. luminositygives max. luminosity here: 4fbhere: 4fb-1-1 / A / A Depending on x & QDepending on x & Q22 might be might be able to take a hit in luminosityable to take a hit in luminosity need to include need to include detector effectsdetector effects
Lets get a feeling for systematic uncertaintiesLets get a feeling for systematic uncertainties1% energy-to-energy normalization1% energy-to-energy normalization
FFLL for fixed electron energy (4GeV) for fixed electron energy (4GeV)and proton energies:and proton energies:50, 70, 100, 250 GeV50, 70, 100, 250 GeVLuminosity: 4fbLuminosity: 4fb-1 -1 each settingeach setting
Measure gMeasure gAA(x) impact parameter (x) impact parameter dependent dependent
E.C. E.C. AschenauerAschenauer
44
Stringent requirements on:Stringent requirements on: Momentum resolution Momentum resolution t resolution and ranget resolution and range
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5
A. Caldwell, H. Kowalski Phys.Rev.C81:025203,2010A. Caldwell, H. Kowalski Phys.Rev.C81:025203,2010
Radiative Correction will impact themRadiative Correction will impact them
Some Info on RadCorsSome Info on RadCors
Inclusive cross sectionInclusive cross section tottot = = elaela + + qelaqela + + inel + inel + vv
for all parts photons can be radiated from the incoming and outgoing for all parts photons can be radiated from the incoming and outgoing lepton, high Z-material Compton peak.lepton, high Z-material Compton peak.
radiation is proportional to Zradiation is proportional to Z22 of target, like bremsstrahlung of target, like bremsstrahlung
radiation is proportional to 1/mradiation is proportional to 1/m2 2 of radiating particle of radiating particle
elastic:elastic:
quasi-elastic: scattering on proton of nuclei quasi-elastic: scattering on proton of nuclei proton stays intactproton stays intact
nuclei breaks upnuclei breaks up two photon exchange? Interference terms? two photon exchange? Interference terms?
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 55
initialinitial finalfinal vacuum loopsvacuum loops
Why are RadCor important?Why are RadCor important?
Modify kinematics Modify kinematics Q Q22:: initial state: E’initial state: E’beambeam = E = Ebeambeam – E – E
photon goes along the beam linephoton goes along the beam line
final state: E’final state: E’outout = E = Eoutout – E – E
photon goes somewhere in Calophoton goes somewhere in Calo
RadCor and detector smearing don’t factorizeRadCor and detector smearing don’t factorize need to have RadCor implemented in MC to unfold effects on need to have RadCor implemented in MC to unfold effects on
kinematicskinematics unfolding in binsunfolding in bins
NNtruetrue=N=Nmeasmeas-N-Nbckgbckg
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 66
eventseventssmeared intosmeared intoacceptanceacceptance
RadCor and smearing unfolding in MCRadCor and smearing unfolding in MC
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 77
generate observed kinematicsgenerate observed kinematicsxxmeasmeas, Q, Q22
measmeas
Radiative Correction CodeRadiative Correction Code
photon radiatedphoton radiated no photon radiatedno photon radiated
xxtruetrue=x=xmeasmeas, , QQ22
truetrue=Q=Q22measmeas
calculatecalculatexxtruetrue, Q, Q22
truetrue
hand kinematics tohand kinematics togenerator (lepto, pythia, ..)generator (lepto, pythia, ..)
What subprocess isWhat subprocess isgenerated is regulatedgenerated is regulated
by phase spaceby phase space
Hand particlesHand particlesto GEANTto GEANT
What do we know?What do we know?
A lot of radiative correction codes for protonA lot of radiative correction codes for proton much less existing for eAmuch less existing for eA
all experiments apart from HERMES had all experiments apart from HERMES had -beams-beamssuppressed radiationsuppressed radiation
HERMES uses modified version of RADGEN HERMES uses modified version of RADGEN (hep-ph/9906408v1)(hep-ph/9906408v1)
Radiative corrections to deep inelastic scattering on heavy Radiative corrections to deep inelastic scattering on heavy nuclei at HERAnuclei at HERA
I. Akushevich and H. SpiesbergerI. Akushevich and H. Spiesberger
http://www.desy.de/~heraws96/proceedings/nuclei/Akushehttp://www.desy.de/~heraws96/proceedings/nuclei/Akushevich.ps.gzvich.ps.gz
QED radiative processes in electron-heavy ion collisions at QED radiative processes in electron-heavy ion collisions at HERAHERA
K. KurekK. Kurek
http://www.desy.de/~heraws96/proceedings/nuclei/Kurek.phttp://www.desy.de/~heraws96/proceedings/nuclei/Kurek.ps.gzs.gz
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 88
What do we know?What do we know?
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 99
RC(A)d A / dyd B
A / dy 1 RC(A)
1RC(A)1RC(D)
1
1010-4-4 < x < 10 < x < 10-3 -3 and 27.5 GeV x 410 GeVand 27.5 GeV x 410 GeV
solid: inelastic rad. correctionssolid: inelastic rad. corrections dashed: inelastic, quasi-elastic and elastic rad. corrections dashed: inelastic, quasi-elastic and elastic rad. corrections
Huge effects at high yHuge effects at high y
PbPbSSCC
HeHeDD
What do we know?What do we know?
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 1010
Compton peak relevant if momentumCompton peak relevant if momentumtransfer to nucleus very smalltransfer to nucleus very small
(1 y)sine'ysin
effect of nuclear form factor includedeffect of nuclear form factor included
What do we know?What do we know?
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 1111
Two photon exchangeTwo photon exchange
two photon exchange only important for very heavy nucleitwo photon exchange only important for very heavy nuclei
Can we suppress things?Can we suppress things?
elastic/quasi-elastic part: require some hadrons in elastic/quasi-elastic part: require some hadrons in detectordetector
solid line: inelastic contributionsolid line: inelastic contribution dashed line: after cuts Edashed line: after cuts E > 10 GeV > 10 GeV E-p E-pz z from hadronic from hadronic
state is smallerstate is smaller
E.C. E.C. AschenauerAschenauer
EIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 1212
Need a code, which puts all together to make full calculationsNeed a code, which puts all together to make full calculationsneed to test analysis strategies to suppress rad. corrections need to test analysis strategies to suppress rad. corrections
SSCC
HeHeDD
DjangohDjangoh http://wwwthep.physik.uni-mainz.de/~hspiesb/djangoh
/djangoh.html is compiled at BNL and running is compiled at BNL and running
eA part is included need to do more studieseA part is included need to do more studies HERACLES can be interfaced with other MC codesHERACLES can be interfaced with other MC codes
HERMES code (RADGEN + eA version of lepto) is HERMES code (RADGEN + eA version of lepto) is installed at BNL and close to run. No nuclear effects installed at BNL and close to run. No nuclear effects are included.are included.
can compare results between eA-RADGEN with can compare results between eA-RADGEN with HERACLESHERACLES can nPDFs be included?can nPDFs be included?
Hubert Spiesberger is coming to INT next week, juhuHubert Spiesberger is coming to INT next week, juhuE.C. E.C.
AschenauerAschenauerEIC INT Program, Seattle 2010 - Week 5EIC INT Program, Seattle 2010 - Week 5 1313
and Summaryand Summary