What Needs to Be Resolved?

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 11

What Needs to Be Resolved?What Needs to Be Resolved?

Functional form does not Functional form does not evolve correctlyevolve correctly– from Qfrom Q00 of 12.6 GeV of 12.6 GeV22 to to

range of 4-100 GeVrange of 4-100 GeV22

Strangeness not conserved Strangeness not conserved (low x)(low x)

Not global fitNot global fit– with outside PDFs, d-quark with outside PDFs, d-quark

distributions not adjusted for distributions not adjusted for changes in s(x)changes in s(x)

Inclusive measurements fit to Inclusive measurements fit to same PDFs with NLO cross-same PDFs with NLO cross-section that go into LO cross-section that go into LO cross-section for dimuonssection for dimuons

Dimuon acceptance mildly Dimuon acceptance mildly inconsistent with datainconsistent with data

mmc c used isn’t best fit to dimuon used isn’t best fit to dimuon

datadata

Nuclear corrections for proton Nuclear corrections for proton PDFs handled consistently in two PDFs handled consistently in two analyses?analyses?

NuTeV CTEQ

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 22

CTEQ “Lepton-Photon” ResultCTEQ “Lepton-Photon” ResultOlness, Tung Olness, Tung et aliaet alia [CTEQ] NLO/LO fit [CTEQ] NLO/LO fit Small asymmetry, ~+10%Small asymmetry, ~+10%(CTEQ NLO d-quark PDFs)(CTEQ NLO d-quark PDFs)

– inconsistency with zero not claimedinconsistency with zero not claimed– uses inclusive data and dimuonsuses inclusive data and dimuons

Paper speculates about errors in NuTeV analysisPaper speculates about errors in NuTeV analysis– Strangeness not conserved at x below charm Strangeness not conserved at x below charm

production thresholdproduction threshold– Evolution not correct for assumed functional formEvolution not correct for assumed functional form– They are good points; do they matter?They are good points; do they matter?

( ) ( )xs x xs x

Main findings of the CTEQ Dimuon Global Analysis pertaining to the Strangeness Asymmetry of the nucleon

parton distributions (so far)

• The dimuon data sets do give the main constraints on s, sbar in the global analysis;

• The shape (width) of the parabola is a robust feature of all current global fits;

• The center of the parabola wanders by ~ 0.1 for different series of LM fits;

• A conservative estimate: -0.1 < [S-]*100 < 0.5 ?

eff2 vs. [S-] for one series of LM fits

The blue curve flops around in different series, hence is not a robust feature of the GA..

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 44

Dimuon Data and AsymmetryDimuon Data and Asymmetry

x region of CTEQ asymmetry is covered by NuTeV dimuon datax region of CTEQ asymmetry is covered by NuTeV dimuon data– so it’s all a question of interpretation…so it’s all a question of interpretation…

CTEQ Asymmetry

NuTeV Dimuons

8 October 2003 K. McFarland, Rochester 5

Comparison of fit-B with data

8 October 2003 K. McFarland, Rochester 6

Comparison of fit-B with data

8 October 2003 K. McFarland, Rochester 7

Comparison of fit-B with data

8 October 2003 K. McFarland, Rochester 8

Comparison of fit-B with data

8 October 2003 K. McFarland, Rochester 9

Comparison of fit-B with data

Ccfr

8 October 2003 K. McFarland, Rochester 10

Comparison of fit-B with data

NuTeV

8 October 2003 K. McFarland, Rochester 11

Comparison of fit-B with data

NuTeV -

8 October 2003 K. McFarland, Rochester 12

Comparison of fit-B with data

Ccfr -

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 1313

What Needs to Be Resolved?What Needs to Be Resolved?

Functional form does not Functional form does not evolve correctlyevolve correctly– from Qfrom Q00 of 12.6 GeV of 12.6 GeV22 to to

range of 4-100 GeVrange of 4-100 GeV22

Strangeness not conserved Strangeness not conserved (low x)(low x)

Not global fitNot global fit– with outside PDFs, d-quark with outside PDFs, d-quark

distributions not adjusted for distributions not adjusted for changes in s(x)changes in s(x)

Inclusive measurements fit to Inclusive measurements fit to same PDFs with NLO cross-same PDFs with NLO cross-section that go into LO cross-section that go into LO cross-section for dimuonssection for dimuons

Dimuon acceptance mildly Dimuon acceptance mildly inconsistent with datainconsistent with data

mmc c used isn’t best fit to dimuon used isn’t best fit to dimuon

datadata

Nuclear corrections for proton Nuclear corrections for proton PDFs handled consistently in two PDFs handled consistently in two analyses?analyses?

NuTeV CTEQ

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 1414

Current NuTeV StatusCurrent NuTeV Status

Have refit at NLO with total strangeness Have refit at NLO with total strangeness constraint of CTEQconstraint of CTEQ

See little change in netSee little change in netmomentum differencemomentum difference– Still precise constraint.Still precise constraint.

Still weakly negativeStill weakly negative– Panagiotis Spentzouris is herePanagiotis Spentzouris is here

and can give details if desiredand can give details if desired

Work is ongoingWork is ongoing

8 October 20038 October 2003 K. McFarland, RochesterK. McFarland, Rochester 1515

Summary on Strange SeaSummary on Strange Sea

A 30% excess of strange momentum overA 30% excess of strange momentum overanti-strange would explain the NuTeV sinanti-strange would explain the NuTeV sin22WW

NuTeV analysis is consistent with zero, weakly NuTeV analysis is consistent with zero, weakly negative using “all-iron” internal PDFsnegative using “all-iron” internal PDFs– uncertainty of 5% with assumed functional formsuncertainty of 5% with assumed functional forms

CTEQ measurement favors +10%CTEQ measurement favors +10%

We need to sort this out, but it won’t “fix” the We need to sort this out, but it won’t “fix” the NuTeV sinNuTeV sin22WW