Heavy Flavour Physics at SJTU Wei Wang Shanghai Jiao Tong - PowerPoint PPT Presentation

Heavy Flavour Physics at SJTU Wei Wang Shanghai Jiao Tong University 2017 SJTU-KIT Collaborative Research Workshop "Particles and the Universe"

LHCb: Tsinghua, GUCAS, CCNU BelleII: IHEP, Beihang

Particle Theory 3 Professors + 4 Associate Professors + 3 Postdoc Xiao-Gang He Hong-Jian He Xiangdong Ji Yue Zhao Jun Gao Wei Wang Pei-Hong Gu

Outline Ø Heavy Flavour Physics Ø Theoretical HFP Activities at SJTU Ø Finite Width Problem in B decays Ø Weak Decays of Doubly heavy baryons Ø Possible connection to HFP Group at KIT

Fundamental Particles Leptons Quarks up tau charm electron muon top electron muon tau down strange bottom neutrino neutrino neutrino 5

Quark Mass Hierarchy m u :2MeV Light m d :5MeV Flavour u c m s :95MeV Heavy m c :1.3GeV Flavour m b :4.7GeV d b s m t :173GeV 6

Heavy Flavour Physics: B Physics ▪ Bound states of b and light quarks mesons : B − , B 0 , B 0 s b , Ξ 0 baryons : Λ b , Ξ − b ▪ Heaviest stable bound states in QCD (>5.2GeV) ▪ Rich spectrum, many decay channels ▪ Important source of information about CP violation, CKM parameters and new physics 7 7

Where do we study heavy flavour? 8 8

(Super) Flavor Factories Experiments providing most of analyses today 3.5 GeV e + 3.1 GeV e + 8 GeV e – 9 GeV e – 10 9 events, leading to Nobel Prize in 2008 Ongoing Experiments 10 11 events, what will happen? Planned facilities Experimental prospect is very promising! 9

Why HFP? C:Matter-AntiMatter CP One needs C and CP violation in PP. 10 10

CP Asymmetry in Hadron System ▪ In Kaon system, the CP asymmetry (CPA) can reach roughly 0.2% ▪ In D decays, CPA at 1% is often argued to be New physics. ▪ Direct CPA in B decays: A cp (B à K + π - )= (-8.2±0.6)%; A cp (B à π + π - ) = (31±5)% ▪ In B decays, sin(2β) = 67.2% ! Large mixing CPA B physics è Ideal Platform to study CPA 11

Why HFP? In the past decades, particle physics goes into two directions: high energy + high precision Ø High Energy：LEP，Tevatron,LHC, … New particles：W,Z,top,Higgs，… Ø High Precision：B factories ,BES,LHCb,Belle-II，… New phenomena 12

B è K * l + l - : Indirect Search for NP Why HFP? ! Within the SM, these processes proceed via loop diagrams like ! New physics entering the virtual parts, could largely alter observables ! Effective Hamiltonian: Wilson coeffs. Operators (short-dist. interactions) (long-dist. interactions) 13 Eli Ben-Haim Moriond QCD and High Energy Interactions, March12th 2013 8

Why HFP: Forward-backward asymmetry θ l : angle of emission between K ? 0 � and µ − in di-lepton rest frame � � θ K ∗ : angle of emission between K ? 0 � � and K − in di-meson rest frame. φ : angle between the two planes � q 2 : dilepton invariant mass square X A FB ( q 2 ) = P F ( q 2 ) − P B ( q 2 ) P F ( q 2 ) + P B ( q 2 ) A.Ali, et. al, hep-ph/9910221 LHCb: 1512.04442 (3fb -1 ) ABSZ: 1503.05534 14

Why HFP: 3.7 σ deviations 5 ' P S 5 0 Form-factor independent observables P 5 = 2 √ LHCb F L (1 � F L ) SM from DHMV 1 LHCb: 1512.04442 0 DHMV:1407.8526 -1 -2 0 5 10 15 2 q 2 [GeV / c 4 ] 8 ' P In PP, 5 σ deviation is a sign for an important discovery. 15

Why HFP: Anomalies in B decays B->D （ * ） tn ， b -> s µµ G. Ciezarek, et.al, Nature 546, 227 (2017) 5 ' P 2 LHCb 1 SM from DHMV 0 -1 -2 0 5 10 15 2 q 2 [GeV / c 4 ] LHCb arXiv: 1705.05802 In PP, 5 σ deviation is a sign for an important discovery. 16

Why HFP: High Precision ▪ QCD Radiative corrections α s / π ∼ 10% → ( α s / π ) 2 ∼ 1% Λ /m b ∼ 20% → ( Λ /m b ) 2 ∼ 4% ▪ High Power corrections ▪ Mismatch between theory and data Γ K ∗ /m K ∗ ∼ 6% → ( Γ K ∗ /m K ∗ ) 2 ∼ 1% 17

Why HFP: Finite Width Problem K* (50 MeV): B à K*l + l - is a four-body process. Experimental cuts by LHCb: LHCb-CONF-2015-002 m K * − δ m < m K π < m K * + δ m L denotes the distribution function of Kπ system from K* Narrow width limit (theoretical results): 18

Why HFP: Finite Width Problem Experimental cuts by LHCb: m K * − δ m < m K π < m K * + δ m We expect the S-wave: Doring, Meissner, WW, 1307.0947 It is mandatory to include the S-wave: 𝐶 → (𝐿𝜌) ' 𝑚 ) 𝑚 * 19

Why HFP: Finite Width Problem ChiPT limited to low energies 20

Unitarized Approach Summing all order contributions: V V + V GV + V GV GV + ... = 1 � GV 1-GV ＝ 0 s=s 0 Above Threshold ： pole corresponds to resonance à Hadron Molecule 21

Unitarized χPT and phase shift 150 M.Döring,U.- K 0 *(1430) 0 ( π K --> π K) [deg] G.Meißner,WW,1307.0947 100 Phase Shift κ (800) δ 1/2 50 0 800 1000 1200 1400 E [MeV] 22

Scalar form factors in χPT 2.0 twice-subtracted Omnes F K π solution matched onto χPT 1.5 Imaginary part Real part Magnitude 1.0 0.5 0.0 0.4 0.6 0.8 1.0 1.2 2 � GeV 2 � m K Π 23

S-wave contributions in B è Kπl + l - 0.14 5.0 0.12 0.10 2.0 0.08 1.0 0.06 0.04 0.5 0.02 0.00 0 1 2 3 4 5 6 0 1 2 3 4 5 6 q 2 � GeV 2 � � b � � GeV 2 � q 2 � a � Decay widths: S-wave fraction Red: total M.Döring,U.G.Meißner,WW,1307.0947 Black: P-wave Blue:S-wave 𝐺 ' = 0.101 ± 0.017 ± 0.009 LHCb:1606.04731 24

Scalar form factors in χPT 1.5 1.5 s F ΠΠ n F ΠΠ 1.0 1.0 f 0 (980): 0.5 a bump 0.5 f 0 (980) 0.0 0.0 a dip � 0.5 � 0.5 � 1.0 � 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 m ΠΠ � GeV � � a � m ΠΠ � GeV � � b � 2 4 25

B s à π + π - µ + µ - b s b s B s B s π + π − π + π − ¯ ¯ s s ( a ) ( b ) 35 60 30 50 � 25 � 40 0.08 GeV 10 8 B 20 0.08 GeV � 30 10 8 B � � � 15 � 20 � � 10 � � � � � 10 � � � � � � � � � � � � 5 � � � � � � � � � 0 � � 0.6 0.8 1.0 1.2 � 0 � � 0.6 0.8 1.0 1.2 Ω � GeV � m Π � Π � � GeV � � b � LHCb:1412.6433 LCSR+ χ PT ： WW,R.Zhu,1502.15104 PQCD: Wang, Li, WW, Lu,1502.15104 26

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We have only started to study the heavy flavour physics…and we need to look from every angle 30

Weak decays of doubly heavy baryons u u Λ + c c c d Ξ ++ ¯ d cc π + u u ¯ K − c s u W + π + ¯ d

Connections with HFP theory Group Institut für Theoretische Teilchenphysik Prof. Dr. Ulrich Nierste Prof. Dr. Matthias Steinhauser Robert Ziegler Institut für Kernphysik Prof. Dr. Monika Blanke Dr. Teppei Kitahara

Conclusion Ø Heavy Flavour Physics Ø Finite Width Problem in B decays Ø Weak decays of Doubly heavy baryons Ø Possible connections with HFP Group at KIT Thank you very much for your attention Vielen Dank! 33

Experimental Prospect of the next generation B factory @ KEK Expected data sample @ full luminosity Integrated luminosity Goal of Be ! e II/SuperKEKB * Channel Belle BaBar Belle II (per year) (ab -1 ) B ¯ 7 . 7 × 10 8 4 . 8 × 10 8 1 . 1 × 10 10 B Belle-II B ( ∗ ) B ( ∗ ) ¯ 7 . 0 × 10 6 6 . 0 × 10 8 − s s 1 . 0 × 10 8 1 . 8 × 10 11 9 months/year Υ (1 S ) 20 days/month 1 . 7 × 10 8 0 . 9 × 10 7 7 . 0 × 10 10 Υ (2 S ) Peak luminosity 1 . 0 × 10 7 1 . 0 × 10 8 3 . 7 × 10 10 Υ (3 S ) (cm -2 s -1 ) 3 . 6 × 10 7 3 . 0 × 10 9 Υ (5 S ) − 1 . 0 × 10 9 0 . 6 × 10 9 1 . 0 × 10 10 ττ * assuming 100% running at each energy Calendar Year � � LHCb � �