B hadron lifetimes in CMS data Jhovanny Mejia , C. Duran, M. Ramirez, - PowerPoint PPT Presentation

B hadron lifetimes in CMS data Jhovanny Mejia , C. Duran, M. Ramirez, I. Heredia, E. De La Cruz-Burelo Cinvestav IPN, Physics department High Energy Physics Group 1 / 16

Introduction • All work presented here is in progress • We make the lifetime measurement of differents hadrons: B s → J / Ψ f 0 , B d → J / Ψ K ∗ , B d → J / Ψ K 0 s , B + u → J / Ψ K + , Λ b → J / ΨΛ 0 and Ξ b → J / ΨΞ − • We can make contributions in different topics of particle physics like heavy quark expansion (HQE) and cp violation. • We will show CMS is competitive in several of the lifetime measurements. 2 / 16

Λ b → J / ΨΛ 0 puzzle τ ( B + ) ≥ τ ( B 0 d ) ≃ τ ( B 0 s ) > τ (Λ 0 b ) ≫ τ ( B − C ) Λ Λ lifetime lifetime b b PDG (2014) -1 ψ Λ LHCb (2012, 1.0 fb ), J/ -1 ψ Λ ATLAS (2013, 4.9 fb ), J/ -1 ψ Λ CDF (2011, 4.3 fb ), J/ -1 ψ Λ CMS (2013, 5.0 fb ), J/ -1 ψ Λ DØ (2012, 10.4 fb ), J/ 280 300 320 340 360 380 400 420 440 460 480 µ m The issue of the Λ b lifetime is not yet solved. 3 / 16

Why the lifetime in B 0 s → J /ψ f 0 (980)? △ Γ = Γ L s − Γ H s = 2 | Γ s 12 | cos φ s φ = φ s + φ ? 4 / 16

Main difficulties with lifetime 5 / 16

B 0 Λ b → J /ψ Λ 0 s → J /ψ f 0 (980) p p p p Ξ b → J /ψ Ξ − B + u → J /ψ K + p p p p 6 / 16

Estimate of lifetime correction Data Data • We searched full simulated MC for B d → J / Ψ + K ∗ decays and divided them in two samples: with displaced vertex trigger and without Sample with Sample without displace vertex trigger displaced displaced triggers triggers 7 / 16

Displaced vertex triggers effects • Effects due to triggers with displaced vertex affects more negative and low proper decay length of the B hadron. • Green no displaced vertex sample and Blue displaced vertex sample L XY · P T λ = M B P T · P T 8 / 16

Triggers correction PDL = 0 . 02 µ m Ratio of displaced vertex to no displaced vertex samples distributions. 9 / 16

Efficiency Due to high variations, we selected values greater than 0 . 02 cm. T = a + b ∗ λ a = 0 . 991559 ± 0 . 01108 b = 0 . 0917707 ± 0 . 147202 chi 2 = 1 . 20528 10 / 16

How the flatness depends on the lifetime? Trigger efficiency on PDL 1 0.8 0.6 T ( λ ) = a + b ∗ λ 0.4 0.2 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 Flatness for PDL > 200 µ m does not depends on the lifetime of the B hadron. 11 / 16

Probability Density Functions (Models) PDF = f s ∗ S M ∗ S λ ∗ S σ ∗ +(1 − f s ) ∗ B M ∗ B λ ∗ B σ • f s : sfraction of signal events • S M : Mass signal pdf • S λ : Signal proper decay length pdf (One exponential decay convoluted with Gaussian Resolution with event per event error) • S σ : Pdf for signal in PDL error distribution (Gaussian convoluted with exponentials) • B M :Background mass pdf (1 order polynomial) • B λ : Pdf for background in PDL (Several exponential decays convoluted with Gaussian Resolution with event per event error) • B σ :Pdf for background in PDL error distribution (Gaussian convoluted with exponentials) 12 / 16

Results Λ b → J / ΨΛ 0 , simultaneous fit Events / ( 0.0064 ) 2 10 Events / ( 0.014 ) work in progress 700 600 2011 data work in progress 500 10 400 300 200 1 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 PDL[cm] 100 5.45 5.5 5.55 5.6 5.65 5.7 5.75 5.8 ψ 2 Events / ( 0.0064 ) Invariant Mass B ^(J/ lambda [GeV/c ] lamb 0 Events / ( 0.014 ) 1600 work in progress 10 2 1400 1200 2012 data work in progress 1000 10 800 600 1 400 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 PDL[cm] 200 5.45 5.5 5.55 5.6 5.65 5.7 5.75 5.8 ψ 2 Invariant Mass B ^(J/ lambda [GeV/c ] lamb 0 Figure: lifetime Simultaneous fit Figure: mass Simultaneous fit 13 / 16

Results B s → J / Ψ f 0 , simultaneous fit Events / ( 0.005 ) 3 10 Events / ( 0.01828 ) 600 work in progress 10 2 500 2011 data work in progress 400 10 300 200 1 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 PDL[cm] 100 5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55 Invariant Mass B 0 (J/ ψ f ) [GeV/c 2 ] Events / ( 0.0064 ) s 0 3 10 Events / ( 0.01828 ) 2000 work in progress 1800 10 2 1600 2012 data work in progress 1400 1200 10 1000 800 600 1 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 PDL[cm] 400 200 5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55 Invariant Mass B 0 (J/ ψ f ) [GeV/c 2 ] s 0 Figure: lifetime Simultaneous fit Figure: mass Simultaneous fit 14 / 16

Summary Decay channel CMS ( µ m ) LHCb ( µ m ) PDG ( µ m ) B s → J / Ψ f 0 501 . 0 ± 11 . 0 510 . 0 ± 12 . 0 509 . 0 ± 12 . 0 Λ b → J / ΨΛ 0 446 . 4 ± 6 . 9 424 . 2 ± 8 . 1 434 . 9 ± 3 . 8 Ξ b → J /ψ Ξ − 457 . 0 ± 44 . 0 464 . 5 ± 30 . 0 467 . 6 ± 81 . 0 B + u → J / Ψ K + 491 . 1 ± 0 . 8 490 . 8 ± 1 . 2 491 . 1 ± 1 . 2 B d → J / Ψ K ∗ 452 . 6 ± 1 . 8 456 . 9 ± 1 . 8 455 . 4 ± 1 . 5 B d → J / Ψ K 0 452 . 8 ± 2 . 7 449 . 4 ± 3 . 9 455 . 4 ± 1 . 5 s Decay Particle Antiparticle Ratio LHCb channel ( µ m ) ( µ m ) ( µ m ) ( µ m ) Λ b → J / ΨΛ 0 452 . 8 ± 9 . 7 439 . 6 ± 9 . 8 1 . 030 ± 0 . 032 0 . 940 ± 0 . 035 B + u → J / Ψ K + 491 . 1 ± 1 . 2 491 . 0 ± 1 . 2 1 . 001 ± 0 . 006 1 . 002 ± 0 . 004 B d → J / Ψ K ∗ 449 . 7 ± 2 . 6 455 . 8 ± 2 . 6 0 . 987 ± 0 . 008 1 . 000 ± 0 . 008 Work in progress 15 / 16

!GRACIAS! 16 / 16