sin(2 /2 1 ) Measurements Riccardo de Sangro INFN - Frascati FPCP - PowerPoint PPT Presentation

sin(2 β /2 Φ 1 ) Measurements Riccardo de Sangro INFN - Frascati FPCP May 19-24, 2013

Outline • Introduction • Recent Experimental results on β • B → c c s • B → q q s • B → c c d • Future prospects • Summary 2 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction Unitarity
rela=on
for
B d 
decays
 B d Unitary Triangle Experimental access to β via TD B( B ) decay rate to same final CP eigenstate with eigenvalue η (assuming ΔΓ =0): ! � ð � t Þ ¼ e � j � t j = � b S tag P � ½ 1 þ S tag S � sin ð � m d � t Þ 4 � b þ S tag C cos ð � m d � t Þ� ; CPV in mixing Negligible in B (~10 -3 ) ⇒ q/p ~1 CPV parameters: � C ¼ 1 � j � j 2 1 þ j � j 2 ; S � ¼� � 2 = m ð � Þ 1 þ j � j 2 ; � ¼ q A with di ff erent w CPV in decay (direct CP) A; p n | A f /A f | � = 1) ¼ þ ð� a B 0 ( � B 0 ), when the tag B is tagged as parameter S tag ¼ þ 1 ð� 1 Þ f f 0 � 0 0 while � ¼ � 1 indicates 1) is the CP eigenvalue for a CP -even (odd) 3 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction For b → c c s “Golden Modes” Penguin 
J/ $ B 0
 B 0
 
K 0
 Negligible penguin, theoretically clean prediction: Theore=cally
clean
as
only
the
tree
level
process
dominates
the
 Interference S η = - η sin(2 β ), C=0 Experimentally clean as well ! a) 1000 1000 b) c) 2 2 0 2 2 0 B J/ K → ψ Events / 2 MeV/c Events / 2 MeV/c Events / 2 MeV/c Events / 2 MeV/c Events / 2 MeV Events / 2 MeV 2000 2000 S 0 0 0 0 0 *0 B (2S)K B J/ K B J/ K → ψ → ψ → ψ 200 200 S L 0 0 B K → χ S c1 500 500 0 0 B K → η 1000 1000 S c 100 100 0 0 0 0 0 0 5.2 5.2 5.22 5.22 5.24 5.24 5.26 5.26 5.28 5.28 0 0 20 20 40 40 60 60 80 80 5.2 5.2 5.22 5.22 5.24 5.24 5.26 5.26 5.28 5.28 2 2 2 2 Δ Δ E (MeV) E (MeV) m m (GeV/c (GeV/c ) ) m m (GeV/c (GeV/c ) ) ES ES ES ES R ⊥ = 0.233 ± 0.010 (stat) ± 0.005 (sys) [PRD 76, 031102(R) (2007)] • Discovery of CPV in the B system by BaBar and Belle(~10 years ago) • Experimentally best known angle of UT 4 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction 
J/ $ 
 
K 0
 as
only
the
tree
lev b → c c s S c c s =- η sin2 β Tree “only” • LHCb B → J/ ψ K s best sin2 β measurement at hadron collider (Phys. Lett. B 721, 2013) • Belle best measurement from a single experiment (PRL 108 (2012) 171802) 5 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction b → q q s q q Penguin dominated modes b s • BaBar TD B 0 → K s K s K s 
J/ $ S PRD 85 (2012) 054023 
 
K 0
 • BaBar TD Dalitz Plot S q q s =sin2 β eff B 0 → K + K - K s as
only
the
tree
lev PRD 85 (2012) 112010 b → c c s S c c s =- η sin2 β Tree “only” • LHCb B → J/ ψ K s best sin2 β measurement at hadron collider (Phys. Lett. B 721, 2013) • Belle best measurement from a single experiment (PRL 108 (2012) 171802) 5 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction b → q q s q q Penguin dominated modes b s • BaBar TD B 0 → K s K s K s 
J/ $ S PRD 85 (2012) 054023 
 
K 0
 • BaBar TD Dalitz Plot S q q s =sin2 β eff B 0 → K + K - K s as
only
the
tree
lev PRD 85 (2012) 112010 b → c c s S c c s =- η sin2 β Tree “only” • LHCb B → J/ ψ K s best sin2 β Small penguin pollution S c c d =sin2 β eff measurement at hadron • Belle first observation collider of CPV in B 0 → D* + D* - (Phys. Lett. B 721, 2013) PRD 86 (2012) 071103(R) • Belle best measurement • BaBar B 0 → D* + D* - from a single experiment partial reconstruction (PRL 108 (2012) 171802) PRD 86 (2012) 112006 b → c c d 5 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Introduction b → q q s q q Penguin dominated modes b s • BaBar TD B 0 → K s K s K s 
J/ $ S PRD 85 (2012) 054023 
 
K 0
 • BaBar TD Dalitz Plot S q q s =sin2 β eff B 0 → K + K - K s as
only
the
tree
lev PRD 85 (2012) 112010 C,S ~same b → c c s S c c s =- η sin2 β in SM Tree “only” • LHCb B → J/ ψ K s best sin2 β Small penguin pollution S c c d =sin2 β eff measurement at hadron • Belle first observation collider of CPV in B 0 → D* + D* - (Phys. Lett. B 721, 2013) PRD 86 (2012) 071103(R) • Belle best measurement • BaBar B 0 → D* + D* - from a single experiment partial reconstruction (PRL 108 (2012) 171802) PRD 86 (2012) 112006 b → c c d Measure S,C in these processes to test SM prediction and look for new physics (NP) 5 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Cast of characters Belle, mostly BABAR, B � � � � � � � � � � � � � � � e e (4S) BB � � 6 (~ 385 10 of each � � � � � � 6 (~ 235 10 of each � � 0 0 � � B , B , B , B ) � � � � � � 0 0 B , B , B , B ) and recently LHCb and � pp bbX � � � � 9 ( 20 10 of each � � � � � � 0 0 B , B , B , B ) � � � � ...more coming 6 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

B-Factories • Production of coherent Signal Selection B B pair from Y(4S) decay with (slight) boost to allow Δ t measurement. • Clean kinematic constraints • ~100% efficiency for B B events Tagging & Time measurement CPV Asymmetry Fit 7 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

LHCb ‣ Tagging algorithms 1(+2) fb -1 integrated luminosity Julian Wishahi | Δ • OS tagging exploits decay of associated b hadron VTX - lepton taggers OS Muon l - OS Electron - kaon tagger b ➝ X l - - inclusive secondary vertex OS Kaon K - b ➝ c ➝ s reconstruction b incoherent Opposite Side production Same Side b ̅ μ d • SS tagging uses remnants J/ ψ Signal σ (b b ) ≈ 75 µb at √ s=7 TeV B d μ of the signal b 2 < η < 6 d ̅ π K S hadronization u π SS Pion - SS Kaon for B s mesons π + - SS Pion for B 0 and B + mesons Candidates / (5 fs) 7000 LHCb 6000 Preliminary* OS tagger performance 5000 4000 ε tag D 2 % Tagger ε tag % ω % 3000 ε tag D 2 ≈ 2 . 3% µ 5.20 ± 0.04 30.8 ± 0.4 0.77 ± 0.04 2000 LHCb e 2.46 ± 0.03 30.9 ± 0.6 0.36 ± 0.03 1000 inary* K 17.67 ± 0.08 39.33 ± 0.24 0.81 ± 0.04 ω ≈ 36 . 7% 0 -0.2 -0.1 0 0.1 0.2 Q vtx 18.46 ± 0.08 40.31 ± 0.24 0.70 ± 0.04 Decay time [ps] ~45 fs time resolution (from prompt J/ ψ ) ~30% at B-Factories 8 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

CP V in b → c c s R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

LHCb Sin2 β [Phys. Lett. B 721, 2013] • 1.0 fb -1 of data (2011, 3.5 TeV) • ~8200 tagged B 0 → J/ ψ K s decays, with J/ ψ→ µ + µ - and K s →π + π - • Used opposite flavor tag only • 1.5% correction for b- b production asymmetry in pp collisions • Magnet polarity reversed periodically ‣ to cancel detector asymmetries • S J/ ψ K 0 S = 0 . 73 ± 0 . 07 (stat) ± 0 . 04 (syst) , S = 0 . 030 ± 0 . 089 C J/ ψ K 0 0 . 091 (stat) ± 0 . 012 (syst) , of ρ ( S J/ ψ K 0 S , C J/ ψ K 0 S ) = 0 . 416. Good agreement with B-Factories results, error ~ x3 that of B factories ➡ Best measurement at hadron colliders! 10 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

Belle Sin2 β [PRL 108, 171802 (2012)] • 772 10 6 B B pairs 400 250 350 3k 5k (b) 300 (a) Events / 0.5 ps Events / 0.5 ps All combined Data 200 B 0 → J/ ψ K S B 0 → J/ ψ K L 4k 250 Events / 50 MeV/c Events / 1 MeV/c 2 B 0 →ψ (2S)K S real J/ ψ , real K L 150 B 0 →χ c1 K S 2k real J/ ψ , fake K L 200 3k Fit result fake J/ ψ 150 100 2k 100 1k 50 50 1k 0 0 5.2 5.22 5.24 5.26 5.28 5.3 0 0.4 0.8 1.2 1.6 2 0.6 0.6 M bc (GeV/c 2 ) p B* (GeV/c) 0.4 0.4 Asymmetry Asymmetry CP eigenvalue ( � f ), signal yield ( N sig ), and purity TABLE I. 0.2 0.2 for each B 0 ! f CP mode. 0 0 N sig Decay mode � f Purity (%) -0.2 -0.2 J= c K 0 � 1 12 649 � 114 97 S -0.4 -0.4 c ð 2 S Þð ‘ þ ‘ � Þ K 0 � 1 904 � 31 92 S c ð 2 S Þð J= c � þ � � Þ K 0 � 1 1067 � 33 90 -0.6 -0.6 S � c 1 K 0 � 1 940 � 33 86 S J= c K 0 þ 1 10 040 � 154 63 -6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 L þ 0 : 642 � 0 : 047 � 0 : 021 t (ps) t (ps) ∆ ∆ Best measurement sin2 � 1 � � � f S f = þ 0 : 667 � 0 : 023 � 0 : 012 þ þ � � 0 : 041 from a single = A f 012 þ 0 : 006 � 0 : 016 � 0 : 012 experiment! 11 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

b → c c s World Average 3% precision δ ( β ) ≈ ±0.6° 12 R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil

CP V in b → q q s R. de Sangro (LNF-INFN) May 19-24, 2013 FPCP 2013 - Buzios, Brasil