NuTeV Structure Function Measurement

Abstract

Abstract. The NuTeV experiment obtained high statistics samples of neutrino and antineutrino charged current events during the 1996-1997 Fermilab fixed target run. The experiment combines sign-selected neutrino and antineutrino beams and the upgraded CCFR iron-scintillator neutrino detector. A precision continuous calibration beam was used to determine the muon and hadron energy scales to a precision of 0.7% and 0.43% respectively. The structure functions F 2 (x, Q 2 ) and xF 3 (x, Q 2 ) obtained by fitting the y-dependence of the sum and the difference of the ν and ν differential cross sections are presented.Neutrino deep inelastic scattering (DIS) provides a unique information for the structure of the proton and QCD, allowing the measurement of two structure functions (SF): F 2 (x, Q 2 ), and the parity-violating xF 3 (x, Q 2 ),which is accessible only by neutrino DIS [1]. The NuTeV experiment is a high-energy fixed target ν − Fe scattering experiment, which combines two new features: Separate high-purity neutrino and antineutrino beams, used to tag the primary lepton in charged-current interactions, and a continuous precision calibration beam, which improves the experiment's knowledge of the absolute energy scale for hadrons and muon, produced in neutrino interactions, to a precision of 0.43% and 0.7% respectively [2]. NuTeV took data during 1996-97 and collected 8.6 × 10 5 ν and 2.4 × 10 5 ν charged-current (CC) interactions that passed analysis cuts. ν-FE CHARGE CURRENT DIFFERENTIAL CROSS SECTIONThe differential cross section is determined fromwhere Φ(E) is the ν(ν) flux in energy bins. The cross section event sample is required to pass fiducial volume cuts, µ track reconstruction quality cuts, a minimum muon energy threshold E µ > 15 GeV, a minimum hadronic energy threshold E HAD > 10 GeV, and a minimum neutrino energy threshold E ν > 30 GeV. Selected events are binned in x, y, and E ν bins, and corrected for acceptance and smearing using a fast detector simulation. Q 2 > 1 GeV 2 is required to minimize the non-perturbative contribution to the cross section. NuTeV data ranges from 10 −3 to 0.95 in x, 0.05 to 0.95 in y, and from 30 GeV to 360 GeV in E ν . The flux is determined from data with E HAD < 20 GeV using the "fixed ν 0 " relative flux extraction method [1]. The integrated number of events in this sample is propor-

Determination of strange sea quark distributions from fixed-target and collider data

“…[41] is not fully quantified. Finally, an internal inconsistency of the inclusive NuTeV data [43] playing a central role in the CTEQ analysis has been recently revealed [44]. As a possible consequence of this inconsistency the CTEQ nPDFs extracted from the NC and CC DIS data are significantly different [45], i.e.…”

“…However, the CTEQ analysis of Ref. [41] is based on the NuTeV data [2,43] only, which do not have the power to constrain all of the PDF components. Therefore, additional external constraints have to be imposed on the CTEQ nuclear PDFs of Ref.…”

Differences between charged-current coefficient functions

“…We now return to the numerical moments (3.1) -(3.3) and investigate their consequences for the x-space functions δc (3) a (x). We follow an approach successfully used, for instance, in Ref.…”

“…In this article we focus on the W-exchange charged-current (CC) case, see Refs. [2][3][4] and [5][6][7][8] for recent measurements in neutrino DIS and at HERA. With six structure functions, F W ± 2 , F W ±…”

“…We discuss their behaviour at the end points x = 0 and x = 1, and provide compact but accurate parametrizations for use in numerical applications. We then proceed, in Section 3, to our new results for the five lowest odd moments of δc (3) 2,L and even moments of δc (3) 3 , as a byproduct deriving the third-order coefficient-function correction to the Gottfried sum rule. These three-loop moments are presented in a numerical form and employed to construct x-space approximations valid at x > ∼ 10 −2 .…”