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Heavy Flavour Physics at HL-LHC Marie-Hélène Schune
LAL Orsay university IN2P3/CNRS LHCb Collaboration
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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 :
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δ
Λeff2
NP coupling
NP scale (mass of new particles)
• Clean predictions from the SM • Precise measurements (including control channels)
General framework : physics topics
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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 :
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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-
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SM : very rare (Vtq, helicity suppression)
Large sensitivity to NP, eg :
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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
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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
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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
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(Bµ µ
! d(B
R(B
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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
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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-
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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
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LHCb
Theory BinnedLHCb
q20
]4c/2 [GeV2q0 5 10 15 20
FBA
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Theory BinnedLHCb CDF BaBar Belle ATLAS CMS
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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
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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
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• 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
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Bs⟶J/ψΦ current results
0.25
CDF
LHCb
ATLAS
Combined
SM
0.20
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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)
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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
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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
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]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
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> = 20µATLAS 2012 <
> = 60 µIBL Layout 11,11 <
> = 200 µITK Layout 11,11 <
ATLAS simulationPreliminary
Bs⟶J/ψΦ
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Decay time [ps]0 5 10
Acceptance
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Upgrade Pythia6Upgrade Pythia8Current (7 TeV)
LHCb Simulation
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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
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Year2012 2014 2016 2018 2020 2022 2024 2026 2028 2030
) rad
s!("
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ATLAS p
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ATLAS p
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• 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
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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
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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
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rees
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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)
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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−( )
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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
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Expected precision on AΓ
SM ~10-4
σsyst ~10-4 evaluated using data driven techniques
FCNC top decays
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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
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tt→ (Z0 + u/c)(W−+ b),(Z0→l+l− +q),(W−→l−ν +b)
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Expected upper limit (95 %CL) on BR(t→qZ)
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Z) in
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ATLAS discriminantATLAS sequential
Expected upper limit (95 %CL) on BR(t→qγ)
2019-2021 2028-2030+ ATLAS 300 fb-1 3000 fb-1
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Summary • History : many breakthroughs in Flavour Physics !
(small CPV in K0 mixing : 3rd family) • Theory uncertainties will be quantified with data
driven techniques
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Back up slides
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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
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Bs⟶ΦΦ
µ=8 (2. 1032 cm-2 s-1 with 25 ns : µ=7.6 )
diff. [fs]! 0sB
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Scal
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ntrie
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Upgrade Pythia6
Upgrade Pythia8
LHCb Simulation
=14 TeVs
= 8µ
Decay time [ps]0 5 10
Acceptance
0
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0.6
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1
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Upgrade Pythia6
Upgrade Pythia8
LHCb Simulation
=14 TeVs
= 8µ