CP Violation in Bs Oscillations at ATLAS,CMS and Tevatron in B s J/ - PowerPoint PPT Presentation

CP Violation in Bs Oscillations at ATLAS,CMS and Tevatron in B s → J/ ψφ James Walder Lancaster University On behalf of the ATLAS, CDF, CMS and D0 Collaborations

Outline • Introduction • B s → J/ ψ φ overview of analyses from: • CDF PRL 109, 171802 (2012) • PRD 85, 032006 (2012) D0 • CMS CMS PAS BPH-11-006 (2012) • New ATLAS ATLAS-CONF-2013-039 (2013) Update of JHEP 12 (2012) 072 • See B. Hoeneisen’s presentation for recents results on asymmetry measurements from D0 2 James Walder FPCP 2013, Buzios, Brazil

CP Violation in Bs system ¯ ¯ b s W ✓ M 11 ✓ Γ 11 ✓ � ↵ ◆ ✓ � ↵ i d � B 0 ( t ) ◆ ◆ � B 0 ( t ) ◆ − i M 12 Γ 12 B 0 B 0 ¯ u, c, t u, c, t = � ¯ � ¯ � � B 0 ( t ) ↵ B 0 ( t ) ↵ M ∗ M 11 Γ ∗ Γ 11 d t 2 s s 12 12 � ¯ � � b � B 0 � B 0 � | B L � = p + q s W � ¯ • � B 0 � � � B 0 � | B H � = p − q Mixing between the flavour states give rise to heavy and light mass eigenstates • ∆ m s = m H s − m L s ≈ 2 | M s ∆ m s ≈ 17 . 77 ps − 1 12 | Mass difference now well-measured; , • Decay width difference (sign established to be Positive): , O (10%) ∆Γ s = Γ L s − Γ H s • CP violation in B s → J/ ψ φ occurs through “interference of mixing and decay” (same final state) J/ ψ φ B 0 • s Experimentally clean decay channel • The CP-violating phase angle ϕ s in B s → J/ ψ φ relates to the CKM matrix ¯ elements with ; ϕ s ~ -0.04 in SM. φ s ≈ − 2 β s B 0 s * ∣ ∣ x * V ts V tb β SM * ∣ ~ 1 β s = arg [ − ( V ts V ∗ tb ) / ( V cs V ∗ cb )] ∣ V cs V cb s * V us V ub ~ λ² V cs V cb • If New Physics, contributions most likely to appear through the phase ϕ s , hence any non-zero observation of this quantity should indicate NP . • φ s = φ SM + φ NP ≈ φ NP s S S • Measurements of the other observable quantities (e.g. ∆Γ ) also test theoretical predictions. 3 James Walder FPCP 2013, Buzios, Brazil

Angular Analysis • B s → J/ ψ φ – pseudo-scalar to vector-vector meson decay • CP-even (L=0,2) and CP-odd (L=1) final states • Distinguishable through time-dependent angular analysis • Results presented here define the 3 angles between final state particles in Transversity basis • From the multi-dimensional fit to the data, the three amplitudes and strong phases can, in principle, be extracted. z • + y Amplitudes: µ µ ψ ψ φ φ J/ rest frame rest frame A 0 − longitudinal CP-even final state A k − transverse CP-even y + θ A ? − transverse CP-odd K T • + Strong Phases: φ K 0 B S ψ ψ J/ T ψ ψ x x T = 0 δ 0 J/ ψ ψ φ φ 0 φ φ B S arg[ A k (0) A ⇤ K δ k = 0 (0)] K xy − plane arg[ A ? (0) A ⇤ δ ? = 0 (0)] (expect phases ~0 or π ) µ µ FERMILAB-PUB-11-646-E θ is the angle between p(µ + ) and the x-y plane in the J/ ψ meson rest frame Φ is the angle between the x-axis and p xy (µ + ), the projection of the μ + momentum in the x-y plane, in the J/ ψ meson rest frame ψ is the angle between p(K + ) and − p(J/ ψ ) in the Φ meson rest frame 4 James Walder FPCP 2013, Buzios, Brazil

General Purpose Detectors • General Purpose Detectors (GPDs) at Tevatron and LHC: • Tevatron – CDF and D0 • LHC – ATLAS and CMS • Varied programmes of physics; from high-p T searches to precision measurements in low-p T regime. • Designed to provide ~4 π Coverage; • Fiducial volume at more central rapidities • Enhancement in bb → J/ ψ to pp → J/ ψ cross-section ratio. • General requirements (with application to B-physics analyses). • Silicon and pixel layers – precision tracking and vertexing; • Calorimetry systems – EM and Hadronic Jets; • Muon system – trigger , event selection. • Particle ID (CDF - time-of-flight detector) for Kaon/pion separation • Background suppression, initial-state flavour-tagging 5 James Walder FPCP 2013, Buzios, Brazil

Tevatron GPD Detectors • Coverage in muon system out to | η |<2 • Particle ID through time-of-flight detector CDF D0 1.4T 1.9T Axial Magnetic field ~0.07% ~0.14% Track momentum resolution σ /p T [GeV] -1 ~90fs ~70fs Lifetime resolution 6 James Walder FPCP 2013, Buzios, Brazil

LHC GPD Detectors ATLAS CMS 2 T 3.8 T Axial Magnetic field Track momentum resolution σ /p T2 [GeV] -1 ~0.05%p T + 0.015 ~0.015%p T + 0.005 ~100 fs ~70 fs Lifetime resolution 7 James Walder FPCP 2013, Buzios, Brazil

Data Taking • Tevatron Run II proton-antiproton operations Tevatron Run II at √ S = 1.96 TeV completed • Each detector accumulated L ~10 fb -1 for analysis. • LHC running at 7 TeV in 2011 proton-proton, 8 TeV 2012, (13 TeV 2015) • ATLAS and CMS collected L ~ 5 fb -1 2011 and ~20 fb -1 in 2012. • Data Taking efficiencies in excess of 90% for all experiments. CMS Integrated Luminosity, pp ] -1 Data included from 2010-03-30 11:21 to 2012-12-16 20:49 UTC 35 Delivered Luminosity [fb 25 25 ATLAS Online Luminosity Total Integrated Luminosity ( fb ¡ 1 ) 2010, 7 TeV, 44.2 pb ¡ 1 2010 pp s = 7 TeV Efficiency ~ 94% 2011, 7 TeV, 6.1 fb ¡ 1 30 2011 pp s = 7 TeV 2012, 8 TeV, 23.3 fb ¡ 1 20 20 2012 pp s = 8 TeV 25 15 15 20 15 10 10 10 5 5 £ 100 5 0 0 0 1 May 1 Jun 1 Jul 1 Aug 1 Sep 1 Nov 1 Dec 1 Apr 1 Oct Apr Jan Jul Oct Month in Year Date (UTC) 8 James Walder FPCP 2013, Buzios, Brazil

Techniques in Bs → J/ ψ φ Analysis • General analysis strategy: Collisions Trigger Optimisation Signal Selection 3.5 3.5 D Run II, MC Signal Background N(events) (Normalized) 3 3 2.5 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 Inclusive BDT Output Fit model Initial-State Flavour-Tagging L ∝ f s P s ( m | � m ) P s ( t, ~ ⇢ , ⇠ |D , � t ) P s ( � t ) P s ( D ) Results! +(1 − f s ) P b ( m ) P b ( t | � t ) P b ( ~ ⇢ ) P b ( � t ) P b ( D ) , ( Time Signal / background dependence Angular analysis separation -1 CMS preliminary, 5 fb s = 7 TeV 1400 Events / 0.04 ps /10) Events / ( 0.0045 GeV ) -1 Data 2200 CMS preliminary, 5 fb 4 Total Fit π 10 ct>0.02cm Events / ( Total Signal 2000 s = 7 TeV 1200 Data B Signal H P( σ t ) Signal B Signal 1800 L Total Background 1000 Background ψ Prompt J/ Background 1600 3 10 Fit ATLAS Preliminary Events / 0.005 ps 1400 800 ct>0.02cm s = 7 TeV ∫ 8000 -1 L dt = 4.9 fb 1200 Data 600 2 10 7000 Total Fit 1000 Signal 6000 800 Background 400 600 5000 10 200 400 4000 ATLAS s = 7 TeV 200 ∫ 0 3000 -1 -3 -2 -1 0 1 2 3 L dt = 4.9 fb T φ [rad] 0 σ 3 T 5 2000 pull by t ¼ M B s ~ L B p= ð p 2 xy � ~ T Þ , 1000 9 0 0 0.1 0.2 0.3 0.4 0.5 σ [ps] James Walder FPCP 2013, Buzios, Brazil t

CDF : Event Selection PRL 109, 171802 (2012) • Analysis using full Run II Dataset at 1.96 TeV (9.6 fb -1 ) • After basic event selection: • Trigger : • • low-pT di-muon triggers Neural Network, trained on signal MC and • 2.7 < m(µµ) <4.0 GeV data sideband for background. • J/ ψ : • Optimised on sensitivity to β s . • pT(µ) > 4 GeV • |m(J/ ψ ) - m PDG (J/ ψ )| < 50MeV • φ : • • Oppositely-charged track pair Observables from the data: • pT(K) > 0.4 GeV • • pT( φ ) > 1.0 GeV m, t, σ (m), σ (t) • |m( φ ) - m PDG ( φ )| < 9.5MeV • Three transversity angles • • B s : Initial state tagging information • µµKK Vertex fit • J/ ψ mass constraint • pT(J/ ψ KK) > 1.0 GeV • • 5.1 < m( J/ ψ KK ) <5.6 GeV After selections ~ 11k B s candidates. • ∆Γ s , τ s , | A ⊥ | 2 , | A 0 | 2 , δ ⊥ Measured quantities: • NN Variable importance: • Kinematic information • Tagged analysis - initial flavour of B meson estimated: • Muon and Hadron PID • • Vertex fit quality Opposite-side tagging ( µ ,e,jet-charge) b 0 • B Same-side tagging from s s s K correlations of Kaon produced in fragmentation (first 5.2 fb -1 ). u/d u/d 10 James Walder FPCP 2013, Buzios, Brazil