12 August 2003Kevin McFarland, University of Rochester NuTeV and the Strange Sea NuTeV/CCFR dimuon data is uniquely sensitive to strange sea  ± from semi-leptonic charm decay NuTeV Paschos-Wolfenstein sin 2  W would agree with SM if strange sea had 30% momentum asymmetry

12 August 2003Kevin McFarland, University of Rochester The Data Forward dimuon d 2  (E)/ dxdy To extract strange sea, need: fragmentation and decay, down quarks Neutrino and anti-neutrino difference (after removing Cabbibo suppressed contribution) is signature of

12 August 2003Kevin McFarland, University of Rochester Neutrino Data

12 August 2003Kevin McFarland, University of Rochester Anti-Neutrino Data

12 August 2003Kevin McFarland, University of Rochester Previous Results Dimuon fits to CCFR/NuTeV data Goncharov et al [NuTeV] LO“+” QCD Zero asymmetry (CTEQ, GRV d-quark PDFs) or Small asymmetry, -(9±5)% (NuTeV internal LO+ d-quark PDFs on iron) Mason et al [NuTeV] NLO [ICHEP02] Zero asymmetry (CTEQ, GRV d-quark PDFs) Inclusive data fits Portheault et al [BPZ update] NLO Zero asymmetry [DIS03]

12 August 2003Kevin McFarland, University of Rochester Last Week… Olness, Tung et alia [CTEQ] LO QCD Small asymmetry, ~+10% (CTEQ d-quark PDFs) inconsistency with zero not claimed uses inclusive data and dimuons Paper speculates that ad hoc NuTeV parameterization may be problem? Strangeness not conserved at x below charm production threshold It’s a good point: does it matter?

12 August 2003Kevin McFarland, University of Rochester Any asymmetry in Dimuons? Collapse the data in E, y as function of x Solid line assumes symmetric sea Dashed is CTEQ asymmetry effect Independent of parameterization, no significant asymmetry

12 August 2003Kevin McFarland, University of Rochester Dimuons and Asymmetry x region of CTEQ asymmetry is covered by NuTeV dimuon data CTEQ Asymmetry NuTeV Dimuons

12 August 2003Kevin McFarland, University of Rochester Conclusions Large strange sea asymmetry can explain NuTeV Paschos-Wolfenstein sin 2  W Gambino’s conclusion “R PW is not a place for precision” based on two flawed assumptions that recent CTEQ central value is right and others are wrong that data can’t control the difference Neither assumption is proven correct

12 August 2003Kevin McFarland, University of Rochester Rumors of the demise of the Paschos-Wolfenstein R - have been greatly exaggerated

12 August 2003Kevin McFarland, University of Rochester Backup: Internal Iron PDF fit

12 August 2003Kevin McFarland, University of Rochester Backup: Isospin Violation Isospin violation in PDFs plausible at level of m q /  QCD ~1% 5% solves NuTeV sin 2  W puzzle MRST have opened a new window! Global PDF fits with isospin violation Early days… Form of parameterization? Other PDFs? Interesting to note: constraints come from CCFR, F 2 d /F 2 p used in NuTeV analysis

12 August 2003Kevin McFarland, University of Rochester Backup: Isospin Violation (2) Naïve analysis (ad hoc addition) of MRST central value suggests  sin 2  W of /3 of a sigma towards Standard Model But sadly, MRST conclude both signs of effect are still allowed by data Empirically, isospin violating PDFs are still a viable explanation but theory is still our best guide about size MRST has given us a great start on testing this. Can it be improved?

12 August 2003Kevin McFarland, University of Rochester Backup: K + e3 Dr. Gambino pointed out that BNL-E865 K + e3 fixes us the 1 st row CKM unitarity problem This also has the uncomfortable side effect of exacerbating the NuTeV sin 2  W easy to see why: electron neutrinos from K + e3 are a major background to neutral current! naïve estimate is that this is +1/2 sigma in sin 2  W if KLOE confirms BNL-E865