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 Xiangdong Ji Pei-Hong Gu Wei Wang Yue Zhao Hong-Jian He Jun Gao

ØHeavy Flavour Physics ØTheoretical HFP Activities at SJTU

ØFinite Width Problem in B decays ØWeak Decays of Doubly heavy baryons

ØPossible connection to HFP Group at KIT

Outline

Quarks

up down charm strange top bottom

Leptons

electron muon tau electron neutrino muon neutrino tau neutrino

5

Fundamental Particles

u c d s b

mu:2MeV md:5MeV ms:95MeV mc:1.3GeV mb:4.7GeV mt:173GeV Light Flavour Heavy Flavour

6

Quark Mass Hierarchy

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▪ Bound states of b and light quarks ▪ 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

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mesons : B−, B0, B0

s

baryons : Λb, Ξ−

b , Ξ0 b

Heavy Flavour Physics: B Physics

8 8

Where do we study heavy flavour?

Experiments providing most of analyses today Ongoing Experiments Planned facilities 3.5 GeV e+ 8 GeV e– 3.1 GeV e+ 9 GeV e–

Experimental prospect is very promising!

109 events, leading to Nobel Prize in 2008 1011 events, what will happen?

(Super) Flavor Factories

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10 10

Why HFP?

C:Matter-AntiMatter CP

One needs C and CP violation in PP.

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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:

Acp(BàK+π-)=(-8.2±0.6)%; Acp(Bàπ+π-) = (31±5)%

▪ In B decays, sin(2β) =67.2%! Large mixing CPA B physicsè Ideal Platform to study CPA

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

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Why HFP?

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Why HFP?

! Within the SM, these processes proceed via loop diagrams like ! New physics entering the virtual parts, could largely alter observables ! Effective Hamiltonian: 8 Eli Ben-Haim Moriond QCD and High Energy Interactions, March12th 2013

Wilson coeffs. (short-dist. interactions) Operators (long-dist. interactions)

BèK*l+l-:Indirect Search for NP

LHCb: 1512.04442 (3fb-1) ABSZ: 1503.05534

• θl: angle of emission between K ?0

and µ− in di-lepton rest frame θK ∗: angle of emission between K ?0 and K − in di-meson rest frame. φ: angle between the two planes q2: dilepton invariant mass square X

AFB(q2) = PF(q2) − PB(q2) PF(q2) + PB(q2)

A.Ali, et. al, hep-ph/9910221

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Why HFP: Forward-backward asymmetry

LHCb: 1512.04442 DHMV:1407.8526

Form-factor independent observables P

5 = S5

√

FL(1FL)

]

4

c /

2

[GeV

2

q

5 10 15

5

' P

• 2
• 1

1 2

LHCb

SM from DHMV

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' P

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In PP, 5σ deviation is a sign for an important discovery.

Why HFP: 3.7σ deviations

Why HFP: Anomalies in B decays

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B->D（*）tn，b-> s µµ

• G. Ciezarek, et.al, Nature 546, 227 (2017)

]

4

c /

2

[GeV

2

q

5 10 15

5

' P

• 2
• 1

1 2

LHCb

SM from DHMV

LHCb arXiv: 1705.05802

In PP, 5σ deviation is a sign for an important discovery.

▪ QCD Radiative corrections ▪ High Power corrections ▪ Mismatch between theory and data

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αs/π ∼ 10% → (αs/π)2 ∼ 1%

Λ/mb ∼ 20% → (Λ/mb)2 ∼ 4%

ΓK∗/mK∗ ∼ 6% → (ΓK∗/mK∗)2 ∼ 1%

Why HFP: High Precision

Experimental cuts by LHCb: mK* −δm < mKπ < mK* +δm

L denotes the distribution function of Kπ system from K*

Narrow width limit (theoretical results):

K* (50 MeV): BàK*l+l- is a four-body process.

LHCb-CONF-2015-002 18

Why HFP: Finite Width Problem

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Experimental cuts by LHCb: mK* −δm < mKπ < mK* +δm It is mandatory to include the S-wave: We expect the S-wave:

Doring, Meissner, WW, 1307.0947

𝐶 → (𝐿𝜌)'𝑚)𝑚*

Why HFP: Finite Width Problem

ChiPT limited to low energies

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Why HFP: Finite Width Problem

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Summing all order contributions: 1-GV＝0

s=s0

Above Threshold： pole corresponds to resonance à Hadron Molecule

V + V GV + V GV GV + ... = V 1 GV

Unitarized Approach

M.Döring,U.- G.Meißner,WW,1307.0947

800 1000 1200 1400 E [MeV] 50 100 150 δ1/2

0 (πK --> πK) [deg]

κ(800) K0*(1430)

Phase Shift

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Unitarized χPT and phase shift

Scalar form factors in χPT

twice-subtracted Omnes solution matched onto χPT Imaginary part Real part Magnitude

0.4 0.6 0.8 1.0 1.2 0.0 0.5 1.0 1.5 2.0

mKΠ

2

GeV2

FKπ

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S-wave contributions in BèKπl+l-

1 2 3 4 5 6 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

q2 GeV2 b

S-wave fraction

1 2 3 4 5 6 0.5 1.0 2.0 5.0

q2 GeV2 a

Decay widths: Red: total Black: P-wave Blue:S-wave 𝐺

' = 0.101 ± 0.017 ± 0.009

LHCb:1606.04731

M.Döring,U.G.Meißner,WW,1307.0947

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Scalar form factors in χPT

0.0 0.2 0.4 0.6 0.8 1.0 1.0 0.5 0.0 0.5 1.0 1.5

mΠΠ GeV a FΠΠ

n

0.0 0.2 0.4 0.6 0.8 1.0 1.0 0.5 0.0 0.5 1.0 1.5

mΠΠ GeV b FΠΠ

s

2 4

f0(980) a dip f0(980): a bump

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Bsàπ+π-µ+µ-

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LCSR+χPT： WW,R.Zhu,1502.15104

LHCb:1412.6433

• 0.6

0.8 1.0 1.2 5 10 15 20 25 30 35

mΠ ΠGeV b

108 B 0.08 GeV

PQCD: Wang, Li, WW, Lu,1502.15104

• 0.6

0.8 1.0 1.2 10 20 30 40 50 60

ΩGeV

108 B 0.08 GeV

b s ¯ s Bs π+π− (b) b s ¯ s Bs π+π− (a)

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

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Weak decays of doubly heavy baryons

u c d ¯ d u ¯ u s u ¯ d u c c W + Ξ++

cc

π+ Λ+

c

K− π+

• Prof. Dr. Ulrich Nierste

Institut für Theoretische Teilchenphysik

• Prof. Dr. Monika Blanke
• Dr. Teppei Kitahara
• Prof. Dr. Matthias Steinhauser Robert Ziegler

Institut für Kernphysik

Connections with HFP theory Group

33

Conclusion

Thank you very much for your attention Vielen Dank! ØHeavy Flavour Physics

ØFinite Width Problem in B decays ØWeak decays of Doubly heavy baryons

ØPossible connections with HFP Group at KIT

• f the next generation B factory @ KEK

Goal of Be!e II/SuperKEKB

9 months/year 20 days/month

Integrated luminosity (ab-1) Peak luminosity (cm-2s-1)

Calendar Year

• * assuming 100% running at each energy

Channel Belle BaBar Belle II (per year) B ¯ B 7.7 × 108 4.8 × 108 1.1 × 1010 B(∗)

s

¯ B(∗)

s

7.0 × 106 − 6.0 × 108 Υ(1S) 1.0 × 108 1.8 × 1011 Υ(2S) 1.7 × 108 0.9 × 107 7.0 × 1010 Υ(3S) 1.0 × 107 1.0 × 108 3.7 × 1010 Υ(5S) 3.6 × 107 − 3.0 × 109 ττ 1.0 × 109 0.6 × 109 1.0 × 1010

*

Expected data sample @ full luminosity

• Experimental Prospect

Belle-II LHCb