heavy flavour physics at hl-lhc · bostjan golob, martijn mulder, sandro palestini , pavel reznicek...

Heavy Flavour Physics at HL-LHC Marie-Hélène Schune

LAL Orsay university IN2P3/CNRS LHCb Collaboration

1

On behalf of the Heavy Flavour subgroup

Inputs from ATLAS, CMS, LHCb and Belle II collaborations

https://twiki.cern.ch/twiki/bin/view/ECFA/PhysicsGoalsPerformanceReachHeavyFlavour

Thanks to Tancredi Carli , Alex Cerri, John Yuan Chao, Jack Kai-Feng Chen, Maria Jose Costa, Roger Forty, Tim Gershon, Bostjan Golob, Martijn Mulder, Sandro Palestini, Pavel Reznicek, Flera Rizatdinova, Maria Smizanska, Roberto Tenchini, Karim Trabelsi and Guy Wilkinson

Motivation •  Precision measurements of CP asymmetries and rare decays

•  A game of coupling and scale :

Heavy Flavours at HL-LHC 01 October 2013 2

δ

Λeff2

NP coupling

NP scale (mass of new particles)

•  Clean predictions from the SM •  Precise measurements (including control channels)

General framework : physics topics

3

small subset of topics not all topics have been studied in every experiment Belle II-only topics not mentioned

FCNC in top decays

Bd,s⟶µ+µ-

ϕs from Bs⟶J/ψΦ

ϕs from Bs⟶ΦΦ

Bd⟶K*0 µ+µ- CKM angle γ

AΓ(D0→KK) and AΓ(D0→ππ)

ATLAS/CMS

LHCb

Belle II

General framework : working hypotheses •  Current results used + improved detectors •  Simulation of running conditions (energy, pile-up)

•  •  integrated luminosities :

4

σ bb( )14 TeV

= 2 ×σ bb( )7 TeV

LHC era HL-LHC era 2010-2012 2015-2017 2019-2021 2024-2026 2028-2030+

ATLAS & CMS 25 fb-1 100 fb-1 300 fb-1 → 3000 fb-1

LHCb 3 fb-1 8 fb-1 23 fb-1 46 fb-1 100 fb-1

Belle II - 0.5 ab-1 25 ab-1 50 ab-1 -

The LHCb upgrade design is qualified for an integrated luminosity of 50<−1 but it is an?cipated that LHCb will con?nue to be opera?onal throughout the HL-‐LHC era

Bd,s⟶µ+µ-


SM : very rare (Vtq, helicity suppression)

Large sensitivity to NP, eg :


From theory : BRs known to 10% (can be improved with refined lattice QCD calculations)

measured with 25% precision

BR(Bs⟶µ+µ-) BR(Bd⟶µ+µ-)

CMS : Phys. Rev. Lett. 111 (2013) 101804, arXiv:1307.5025. LHCb : Phys. Rev. Lett. 111 (2013) 101805, arXiv:1307.5024. Combination : CMS-PAS-BPH-13-007 ; LHCb-CONF-2013-012


Bd,s⟶µ+µ- : what’s next ?

•  Measure Bd and Bs : NP effects can be different •  HL-LHC : BR(Bs) will be limited (theory, fd/fs or Bs absolute BR) •  Use Bd ! •  B mass resolution is crucial :

•  CMS and LHCb can do it. •  ATLAS mass resolution has to be improved. •  Bd⟶µ+µ- suffers from Bd⟶Kπ background


CMS 300 fb-1 CMS 3000 fb-1

improved inner tracker system and removal of the endcap candidates

Year2016 2018 2020 2022 2024 2026 2028 2030

)) %

µ µ ! s

)/BR

(Bµ µ

! d(B

R(B

"

0

20

40

60

80

100

120

140

160

180

200CMSLHCb


But also : measurement of the Bs⟶µ+µ- effective lifetime (clean test of NP) with ~2000 events

σtheory ~5 %

Precision computed assuming the SM BR

Expected precision on BR(Bd⟶µ+µ-)/BR(Bs⟶µ+µ-)

2012


SM :

Distributions of the angular variables precisely predicted in the SM Deviations expected from NP Probe the NP structure if any effect observed : eg in the low q2 region the Ф distribution is sensitive to the photon polarization

µ+

µ- K-

π+

Ф

B θK θℓ

System described by • q2 =M2(ℓℓ) • 3 angles

Angular observables in Bd⟶K*0 µ+µ-


sensitive to RH-couplings (C’

7) at low q2

AFB(q20) = 0

used as a reference

Important phenomenological work to construct observables with low theoretical uncertainties

]4c/2 [GeV2q0 5 10 15 20

FBA

-1

-0.5

0

0.5

1

LHCb

Theory BinnedLHCb

q20

]4c/2 [GeV2q0 5 10 15 20

FBA

-1

-0.5

0

0.5

1

Theory BinnedLHCb CDF BaBar Belle ATLAS CMS


Current results :

Relative weights of the LHC experiments depend on the q2 bin ‘cleanness’ varies with bins (resonances in M(µ+µ-))

J/ψ ψ(2S)

ATLAS : ATLAS- CONF-2013-038. CMS : arXiv:1308.3409. LHCb : JHEP 08 (2013) 131

Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

) % 02(q!

0

5

10

15

20

25

30

35

40

45

50Belle IILHCb


Expected precision on q20

•  triggering at low muon pT is mandatory •  AFB is not the best variable (contains hadronic uncertainties) •  much more than that in Bd⟶K*0 µ+µ- analyses

σtheory ~7 %

K∗l+l−, where l = e or µ and K∗ includes both K∗0 and K∗+

ϕs from Bs⟶J/ψΦ and Bs⟶ΦΦ


• Requires : •  initial state tagging •  time measurement •  angular analysis (VV final state) to disentangle CP-even and CP-odd contributions •  measurement of ΔΓS

CP violation due to the interference between mixing and decay


Bs⟶J/ψΦ current results

0.25

CDF

LHCb

ATLAS

Combined

SM

0.20

0.15

0.10

0.05

0-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

68% CL contours( )

HFAGApril 2013

LHCb 1.0 fb –1 + CDF 9.6 fb –1 + ATLAS 4.9 fb 1+ D 8 fb– –1

D

ATLAS (2011) φs = 0.12 ± 0.25(stat.) ± 0.11(syst.) rad LHCb(2011) φs = 0.01 ± 0.07(stat.) ± 0.01(syst.) rad

ATLAS : ATLAS-CONF-2013-039. LHCb : Phys. Rev. D87 (2013) 112010

ΔΓs=Γ L

-ΓH (

ps-1)


Bs⟶J/ψΦ

Bs⟶ΦΦ

tree diagram

NP can show up in the mixing

b → ccs

penguin diagram

NP can show up in the mixing or in the decay (penguin loops)

b → sss

LHCb only

SM


Knowledge of the time resolution is crucial for ϕs measurements Under control even in tough conditions !

Improvements wrt 2012 due to detector change and to tighter pT cuts

) [GeV]0s(B

Tp

0 10 20 30 40 50 60 70 80

) [ps

]0 s

(B

00.020.040.060.08

0.10.120.140.160.180.2

> = 20µATLAS 2012 <> = 60 µIBL Layout, <> = 200 µITK Layout, <

ATLAS simulationPreliminary

Number of reconstructed PV

0 10 20 30 40 50 60 70 80 90 100) [

ps]

0 s(B

00.020.040.060.08

0.10.120.140.160.180.2

> = 20µATLAS 2012 <

> = 60 µIBL Layout 11,11 <

> = 200 µITK Layout 11,11 <

ATLAS simulationPreliminary

Bs⟶J/ψΦ


Decay time [ps]0 5 10

Acceptance

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Upgrade Pythia6Upgrade Pythia8Current (7 TeV)

LHCb Simulation

=14 TeVs

= 4µ

Bs⟶ΦΦ

Better decay time resolution and increased decay time acceptance due to the improved IP resolution

Similar performances at µ=8 (2. 1033 cm-2 s-1 with 25 ns : ν=7.6 )

diff. [fs]! 0sB

-200 -100 0 100 200

Scal

ed E

ntrie

s

0

500

1000

1500

2000

2500

3000 Upgrade Pythia6Upgrade Pythia8Current (7 TeV)

LHCb Simulation

=14 TeVs

= 4µ

Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

) rad

s!("

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2 )> 6-11 GeVµ(T

ATLAS p

)> 11 GeVµ(T

ATLAS p

)! #LHCb (J/

)! !LHCb (


•  A crucial ingredient is the effective tagging efficiency and its knowledge •  Importance of the J/ψ trigger

σJ/ψΦ th ~0.003

σΦΦ th ~0.02

Expected precision on ϕs (rad)

can be quantified with data)

conservative

The CKM angle γ


Interferences between b→c and b→u transitions

Time independent measurements (B→DK(*) large family) Tree diagrams SM reference point

Time dependent measurements (Bs→DsK) tree (decay) + box (mixing) diagrams sensitive to NP in mixing (Bs⟶J/ψΦ )

charmless decays box/loops diagrams sensitive to NP


B→D(KK)K B→D(KK)K*

B→D(ππ)K

B→D(ππ)K*

B→D(Kπ)K B→D(Kπ)K*

B→D(Kπ) π

B→D(Kshh)K

Bs→D(KK)φ

Bs→D(ππ)φ

Bs→D(Kπ)φ

Bs→DsK

B→D(Kπ)K ππ B→D(K3π)K

The “ultimate” γ-from tree-decays precision will be reached through many individual measurements, with very different sensitivities (due to different b→u to b→c amplitudes ratio )

Some of them are challenging at the LHC (many tracks, low pT, hadronic trigger)

B→D(K*K)K

B→D(KK) π

Λb→ DKp

B→D(4π)K

LHCb only

LHCb and Belle II

Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

) deg

rees

!("

0

2

4

6

8

10

12

14 Belle IILHCb


Expected precision on γ from tree decays

Precise measurements : comparison with loop measurements possible to a very good level

σtheory negligible

σsyst ~<1°

AΓ taken as a reference :

•  AΓ ≠ 0 ⇒CPV in charm mixing (SM : ~10-4) •  AΓ(D0→KK) ≠ AΓ(D0→ππ) ⇒direct CPV

AΓ(D0→KK) and AΓ(D0→ππ)


FCNC decays for up-type quarks : a different place to look for NP

AΓ =τ D0 → h+h−( ) − τ D0 → h+h−( )τ D0 → h+h−( ) + τ D0 → h+h−( )


LHCb

A crucial ingredient for fully hadronic decays (trigger) and to be able to measure AΓ to a very good precision : the impact parameter resolution

Upgrade conditions

Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

-4) i

n 10

!(A"

0

2

4

6

8

10

12

14

16

18

20Belle IILHCb


Expected precision on AΓ

SM ~10-4

σsyst ~10-4 evaluated using data driven techniques

FCNC top decays


In the SM :

mtop ≫ mother quarks ⇒FCNC in the top sector highly suppressed

NP : can be increased up to 10-4 Search for • tt→ (Z0u/c)(W−b),Z0→l+l−,W−→l−ν Three leptons in final state : high trigger efficiency

• tt→ (γ u/c)(W−b),W−→l−ν

<10-14


tt→ (Z0 + u/c)(W−+ b),(Z0→l+l− +q),(W−→l−ν +b)


Expected upper limit (95 %CL) on BR(t→qZ)

Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

-5 q

Z) in

10

!U

pper

lim

it 95

% C

L (t

0

10

20

30

40

50

60

70

80

90

100CMS sequential

ATLAS discriminantATLAS sequential

Expected upper limit (95 %CL) on BR(t→qγ)

2019-2021 2028-2030+ ATLAS 300 fb-1 3000 fb-1

7.8 10-5 1.3 – 2.5 10-5

Summary •  History : many breakthroughs in Flavour Physics !

(small CPV in K0 mixing : 3rd family) •  Theory uncertainties will be quantified with data

driven techniques


Back up slides



Towards a full angular analysis of Bd⟶K*0µ+µ-

If all bins independent, the probability of having such deviation or greater is 0.5% More data needed to clarify the picture

all bins (24) in q2 in agreement with SM except 1


Bs⟶ΦΦ

µ=8 (2. 1032 cm-2 s-1 with 25 ns : µ=7.6 )

diff. [fs]! 0sB

-200 -100 0 100 200

Scal

ed E

ntrie

s

0

500

1000

1500

2000

2500

3000

Upgrade Pythia6

Upgrade Pythia8

LHCb Simulation

=14 TeVs

= 8µ

Decay time [ps]0 5 10

Acceptance

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Upgrade Pythia6

Upgrade Pythia8

LHCb Simulation

=14 TeVs

= 8µ

heavy flavour physics at hl-lhc · bostjan golob, martijn mulder, sandro palestini , pavel reznicek...

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