Deep Inelastic Scattering: Recent Results and Future D.Naples - PowerPoint PPT Presentation

Deep Inelastic ν Scattering: Recent Results and Future D.Naples University of Pittsburgh NuInt 2007 Fermilab June 3, 2007

Outline ◮ Overview of Neutrino DIS ◮ Recent Results • NuTeV High energy range • Chorus 10-300 GeV WIP • Nomad ◮ Future WIP Low energy range • Minos 5-50 GeV • Minerva – p.1/ ??

CC Neutrino Deep Inelastic Scattering Lorentz-invariant quantities in terms of measured E µ , θ µ , E had : ν − ν µ µ − µ µ 8 Q 2 = 4( E µ + E had ) E µ sin 2 θ µ → Squared 4-momentum transfer > 2 > > Q 2 > > x = → Fractional struck quark momentum > 2 ME had > > W + < E had W + y = → Inelasticity E µ + E had > W 2 = M 2 + 2 ME HAD − Q 2 > xP → Squared invariant final state mass > xP > > > > > ν = E had → Energy transfered to hadronic system : E had E had Neutrino Scattering Cross-Section: G 2 d 2 σ ν ( ν ) + y 2 F ME ν »„ 1 − y − Mxy « ± y (1 − y – F ν ( ν ) 2 2 xF ν ( ν ) 2 ) xF ν ( ν ) = 2 1 3 Q 2 dxdy 2 E ν W ) 2 π (1 + M 2 Structure functions in the parton model: h xq ν ( ν ) + xq ν ( ν ) i 2 xF 1 ( x, Q 2 ) = 1+(2 Mx/Q )2 ◮ 2 xF ν ( ν ) 1+ R ( x,Q 2) F 2 ( x, Q 2 ) ( x, Q 2 ) = Σ 1 h xq ν ( ν ) + xq ν ( ν ) + 2 xk ν ( ν ) i ◮ F ν ( ν ) ( x, Q 2 ) = Σ 2 h xq ν ( ν ) − xq ν ( ν ) i ◮ xF ν ( ν ) ( x, Q 2 ) = Σ 3 – p.2/ ??

Neutrinos as Probes Challenges ◮ ν Flux spectrum is difficult to predict/measure. ◮ Statistical precision • Require highly intense ν beams. • Massive Detectors ⇒ Nuclear Effects F 2 → measured precisely by charged-lepton DIS. xF 3 → uniquely determined by neutrino DIS ◮ Sensitive to valence quark distributions. ◮ Non-singlet QCD evolution, theoretically more robust. ◮ ∆ xF 3 ⇒ sensitive to strange and charm pdfs. x ( F ν 3 − F ν 3 ) = 4 x ( s − c ) – p.3/ ??

High Energy Range: NuTeV, Chorus, Nomad – p.4/ ??

- (k ′ ) ν µ (k) µ NuTeV + (q) W X(p ′ ) N(p) ◮ Data taking: 1996-97 FNAL fixed target. ◮ Many physics topics ⇒ Main motivation: precise meas. of sin 2 θ W . [PRL 88, 091802 (2002)] ◮ Iron Calorimeter + Muon Spectrometer ◮ SF events: 8 . 6 × 10 5 ν and 2 . 3 × 10 5 ν B = 15kG φ < E ν > ∼ 120 GeV, < Q 2 > ∼ 25 GeV 2 ∆ E 0.86 = E E Steel/scint 10cm sampling ∆ P Tracking 20cm sampling P ~ 11% ◮ Sign-selected: Separate high-purity ν or ¯ ν • ν mode 3 × 10 − 4 ν • ν mode 4 × 10 − 3 ν ◮ Tags leading muon in CC interactions • Toroid polarity always focusing ’right’ sign µ . • Lead µ → Dimuon event sample – p.5/ ??

� � ✁ ✁ ✁ ✁ � � � � � � � - (k ′ ) ν µ (k) µ Continuous Calibration + (q) W X(p ′ ) N(p) ν v o k n e r e C D R TEST BEAM m T 0 7 m 3 8 Beam cycle test beam neutrinos Precise in-situ calibration of NuTeV Detector: ◮ Alternate every cycle with Neutrino beam. ◮ Hadrons, muons, electrons (4.5–190GeV) ◮ Ability to map response. ◮ IMPROVED: Calibration of Energy Scale. ∆ E HAD = 0 . 43% • Hadrons: E HAD ∆ E µ • Muons: = 0 . 7% E µ – p.6/ ??

- (k ′ ) ν µ (k) µ Cross Section Extraction + (q) W X(p ′ ) N(p) d 2 σ ν ( ν ) ∆ N ν ( ν ) 1 ijk ijk Differential Cross Section in terms of flux and number of events: ∝ Φ( E ν dxdy i ) ∆ x j ∆ y k ◮ Data: • CC Event Sample: toroid analyzed muon ◮ [Phys. Rev. D 74, 012008 (2006)] ⋆ Containment and good muon track ⋆ E µ > 15 GeV , E ν ∈ (30 , 350) GeV , Data • Flux Sample: Flux Cross Section ⋆ Low ν CC events ( E had < 20 GeV ) sample sample • Cross Section Sample: ⋆ E had > 10 GeV , Q 2 > 1 GeV 2 ◮ Monte Carlo: Cross • Used for acceptance and smearing corrections Flux Section • Cross-Section Model ⋆ LO QCD inspired parametrization: fi t to data : [A.Buras, K.Gaemers; Nucl.Phys.B132,249(1978) ⋆ Data with lower Q 2 at high- x ( x > 0 . 4 ) included Monte Carlo in fi t to constrain higher-twist. (SLAC,NMC,BCDMS) ⋆ for Q 2 < 1 . 35 GeV 2 use GRV Q 2 evolution Cross Section Model +Detector Simulation • Detector model: ⋆ E µ and E had resolution functions parametrized using test beam ⋆ θ µ parametrized using GEANT hit level MC – p.7/ ??

- (k ′ ) ν µ (k) µ Relative Flux Extraction + (q) W X(p ′ ) N(p) ◮ Flux normalized using total neutrino cross “Low ν method”: Integrate data at low ν ( < 20 GeV) section world average (30-200 GeV): σ ν E = 0 . 677 ± 0 . 014 × 10 − 38 cm 2 ◮ Integrate diff. cross section over x at fi xed ν : GeV ν 2 dσ 1+ B ν − C ◮ Test of Flux extraction: ν → 0 dν = A ( ) → A − 2 E 2 A E ν A ν |{z} | {z } 0.8 small small Neutrino Z σ /E x 10 -38 cm 2 /GeV 0.7 8 G2 FM F 2 (x , Q 2 )dx A = > π > > 0.6 > > Z ˆ F 2 (x , Q 2 ) ∓ xF 3 (x , Q 2 ) ˜ dx G2 > FM < B = − 0.5 π 1 + 2Mx ! > 1 + R(x , Q 2 ) − Mx Z > Antineutrino G2 0.4 > FM F 2 (x , Q 2 ) ν ν − 1 dx > C = B − > π > : 0.3 E ) 2 terms small at low ν and high E. 0.2 ◮ ν E and ( ν 50 100 150 200 250 300 350 E ν (GeV) ◮ Cross section constant, indep. of E ν σ ν E ν is flat as function of E ν ◮ Φ(E) ∝ N(E , ν < ν o ) ◮ σ ν Z ν 0 dN σ ν agrees with world average ◮ dν Φ( E ν ) = dν ν 2 1 + B E ν − C ν 0 2 E 2 A A ν ◮ Fit to dN d ν data determines B C A , A – p.8/ ??

- (k ′ ) ν µ (k) µ Modeling of Data + (q) W X(p ′ ) N(p) x 10 Events per 10GeV Data/MC 1.1 30000 1.1 Events per 10GeV Data/MC 1.05 10000 20000 1.05 7500 1 1 5000 10000 0.95 0.95 2500 0.9 0 0.9 100 200 300 100 200 300 0 100 200 300 100 200 300 E µ (GeV) E µ (GeV) E µ (GeV) E µ (GeV) x 10 2 1.1 Events per 10GeV Data/MC 1.1 Events per 10GeV Data/MC 60000 1.05 1500 1.05 40000 1 1000 1 0.95 20000 0.95 500 0.9 0 0.9 0 100 200 300 100 200 300 100 200 300 100 200 300 E HAD (GeV) E HAD (GeV) E HAD (GeV) E HAD (GeV) Events per 5mrad Data/MC 1.1 1.1 Events per 5mrad Data/MC 20000 1.05 60000 1.05 1 40000 1 10000 0.95 0.95 20000 0.9 0.9 0 0 0 0.05 0.1 0.15 0 0.05 0.1 0.15 0 0.05 0.1 0.15 0 0.05 0.1 0.15 θ µ (rad) θ µ (rad) θ µ (rad) θ µ (rad) ◮ Monte Carlo Describes the data well over entire kinematic range. ( χ 2 /dof=2225/2599) • E µ and E HAD Smearing parameterized from Test beam measurements. • θ µ from Geant Detector simulation. – p.9/ ??

- (k ′ ) ν µ (k) µ Cross Section Systematic Uncertainties + (q) W X(p ′ ) N(p) Provide a point-to-point covariance matrix: 7 systematic uncertainty sources considered: M αβ = P 7 i δ i | α δ i | β • E µ and E HAD scales (affect both cross • δ i | α is the 1 σ shift in data point α due to systematic section and flux extraction) uncertainty i of size ǫ i . • m c and B A (are important for the flux dxdy (+ ǫi ) − d 2 σ d 2 σ dxdy ( − ǫi ) extraction . m c =1.4 ± 0.18. δ i | α = 2 • E µ and E HAD smearing models. ◮ χ 2 including all systematic uncertainties: (important at high energy). X χ 2 = ( D α − f theory ) M − 1 αβ ( D β − f theory ) α β • Cross section model uncertainty (small). αβ • overall normalization uncertainty 2 . 1% • M αβ is point to point covariance matrix: (from uncertainty in world average • D α - measured differential cross section absolute cross section at high energy.) • f theory - the model prediction α – p.10/ ??

- (k ′ ) ν µ (k) µ NuTeV Differential Cross Section + (q) W X(p ′ ) N(p) Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino Anti-Neutrino x=0.015 1.5 1 0.5 ◮ Extracted ν ( ν ) − Fe Cross-Sections in x bins 2 x=0.045 E ν = 65 GeV 1.5 1 NuTeV 2 x=0.125 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1/E d 2 σ /dxdy (x 10 -38 cm 2 /GeV) 1.5 CCFR 1 0.5 2 x=0.175 CDHSW 1.5 1 0.5 • CDHSW [Z. Phys C49 187, 1991] x=0.275 1.5 1 • CCFR [PRL 86 2742, 2001, U.K Yang, Thesis] 0.5 x=0.35 1 ◮ Better control of largest systematic uncertainties: 0.5 E µ scale E had E ν range 0.6 x=0.55 0.4 CDHSW 2% 2.5% 20-200 GeV 0.2 CCFR 1% 1% 30-400 GeV x=0.65 0.2 0.1 NuTeV 0.7% 0.43% 30-350 GeV 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) (E=65 GeV) – p.11/ ?? ▽