Mixing and time-dependent CP violation in beauty at LHCb Katya - - PowerPoint PPT Presentation

Moriond EW 2019

Mixing and time-dependent CP violation in beauty at LHCb

Katya Govorkova

• n behalf of the LHCb Collaboration

2 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

Decays of B⁰s (B⁰s) to J/ψ h˖h˗ CP violation in interference between direct decay and decay after mixing

Weak phase

S

B0

s

φ J/ψ W + s b s s c c V ∗

bc

Vcs

+

h⁺h⁻

_

2 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

Decays of B⁰s (B⁰s) to J/ψ h˖h˗ CP violation in interference between direct decay and decay after mixing

Weak phase

S

B0

s

φ J/ψ W + s b s s c c V ∗

bc

Vcs

+

h⁺h⁻

B0

s

φ J/ψ u, c, t W b W s u, c, t W − b s s s c c Vts Vbc Vts V ∗

cs

h⁺h⁻

_

@lisbouche

2 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

Decays of B⁰s (B⁰s) to J/ψ h˖h˗ CP violation in interference between direct decay and decay after mixing

Weak phase

S

B0

s

φ J/ψ W + s b s s c c V ∗

bc

Vcs

+

h⁺h⁻

B0

s

φ J/ψ u, c, t W b W s u, c, t W − b s s s c c Vts Vbc Vts V ∗

cs

h⁺h⁻

𝜚s = 𝜚mix - 2𝜚dec

_

2 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

Decays of B⁰s (B⁰s) to J/ψ h˖h˗ CP violation in interference between direct decay and decay after mixing

CP

Weak phase Weak phase

• S

B0

s

φ J/ψ W + s b s s c c V ∗

bc

Vcs B0

s

φ J/ψ u, c, t W b W s u, c, t W − b s s s c c Vts Vbc Vts V ∗

cs

S

B0

s

φ J/ψ W + s b s s c c V ∗

bc

Vcs

+

h⁺h⁻

B0

s

φ J/ψ u, c, t W b W s u, c, t W − b s s s c c Vts Vbc Vts V ∗

cs

h⁺h⁻ h⁺h⁻ h⁺h⁻

𝜚s = 𝜚mix - 2𝜚dec

_

NP If 𝝔sexp ≉ 𝝔sSM

New Physics!

3 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

ϕSM

s

≈ − 2 arg( VtsV*

tb

VcsV*

cb) = − 0.03686 +0.00096 −0.00068 rad

[CKM fitter]

s

β γ γ α α

d

m ∆

K

ε

K

ε

s

m ∆ &

d

m ∆

ub

V β sin 2

s

β excluded at CL > 0.95

sb

ρ

• 0.10
• 0.05

0.00 0.05 0.10

sb

η

• 0.10
• 0.05

0.00 0.05 0.10

excluded area has CL > 0.95 Summer 18

CKM

f i t t e r

* Sensitive probe of New Physics in B⁰s mixing * Precise test of Standard Model through the measurement of 𝜚s

NP If 𝝔sexp ≉ 𝝔sSM

New Physics!

3 Katya Govorkova

CP violation in B⁰s

Moriond EW 2019 21 March 2019

ϕSM

s

≈ − 2 arg( VtsV*

tb

VcsV*

cb) = − 0.03686 +0.00096 −0.00068 rad

[CKM fitter]

s

β γ γ α α

d

m ∆

K

ε

K

ε

s

m ∆ &

d

m ∆

ub

V β sin 2

s

β excluded at CL > 0.95

sb

ρ

• 0.10
• 0.05

0.00 0.05 0.10

sb

η

• 0.10
• 0.05

0.00 0.05 0.10

excluded area has CL > 0.95 Summer 18

CKM

f i t t e r

* Sensitive probe of New Physics in B⁰s mixing * Precise test of Standard Model through the measurement of 𝜚s

Katya Govorkova Moriond EW 2019 21 March 2019 4

Measurement of CPV at LHCb

Katya Govorkova Moriond EW 2019 21 March 2019 5

μ˗ μ˖ h˖ h˗

J/ψ

p p B⁰s Inside the VELO B⁰s flies ~ 1cm

Measurement of CPV at LHCb

Katya Govorkova Moriond EW 2019 21 March 2019 5

μ˗ μ˖ h˖ h˗

J/ψ

p p B⁰s Inside the VELO B⁰s flies ~ 1cm

Measurement of CPV at LHCb

h- h+ h+h-

Helicity angles formalism

6 Katya Govorkova Moriond EW 2019 21 March 2019

Measurement of CPV at LHCb

Angular analysis is required to disentangle CP-even and CP-odd final state admixture

6 Katya Govorkova Moriond EW 2019 21 March 2019

Measurement of CPV at LHCb

d4Γ dt dΩ ∼ ∑

k

fk(Ω) ε(t, Ω) (1 − 2ω) hk(t|B0

s ) ⊗ G(t|σt)

Ω Ω ε Ω σt ω hk

• mistag probability of flavour tagging
• efficiency as a function of decay time and angles
• decay time resolution

ε

σt

ω

Angular analysis is required to disentangle CP-even and CP-odd final state admixture

6 Katya Govorkova Moriond EW 2019 21 March 2019

Measurement of CPV at LHCb

d4Γ dt dΩ ∼ ∑

k

fk(Ω) ε(t, Ω) (1 − 2ω) hk(t|B0

s ) ⊗ G(t|σt)

Ω Ω ε Ω σt ω hk

hk = e−Γst (ak cosh ΔΓst 2 + bk sinh ΔΓst 2 + ck cos(Δmst) + dk sin(Δmst))

hk

Γs = ΓH + ΓL 2 ΔΓs = ΓL − ΓH

• mistag probability of flavour tagging
• efficiency as a function of decay time and angles
• decay time resolution

ε

σt

ω

Angular analysis is required to disentangle CP-even and CP-odd final state admixture

|BL > = p|B0

s > + q| ¯

B0

s >

|BH > = p|B0

s > − q| ¯

B0

s >

≈ CP-even ≈ CP-odd

λ = η q p ¯ Af Af

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

in preparation

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

ΔΓs and Γs - ΓB⁰

to test the Heavy Quark Expansion prediction of Γs / ΓB⁰ = 1.0006 ± 0.0025

in preparation

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

ΔΓs and Γs - ΓB⁰

to test the Heavy Quark Expansion prediction of Γs / ΓB⁰ = 1.0006 ± 0.0025

ΓH - ΓB⁰

since the final state is almost entirely CP-odd

in preparation

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

ΔΓs and Γs - ΓB⁰

to test the Heavy Quark Expansion prediction of Γs / ΓB⁰ = 1.0006 ± 0.0025

ΓH - ΓB⁰

since the final state is almost entirely CP-odd Simultaneous fit to the decay time and three helicity angles

in preparation

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

ΔΓs and Γs - ΓB⁰

to test the Heavy Quark Expansion prediction of Γs / ΓB⁰ = 1.0006 ± 0.0025

ΓH - ΓB⁰

since the final state is almost entirely CP-odd Simultaneous fit to the decay time and three helicity angles

1000 1020 1040 ]

2

c [MeV/ )

−

K

+

m(K 2000 4000 6000 8000 10000 )

2

c Weighted cands. / (0.6 MeV/ LHCb

LHCb Preliminary

in 6 m(K˖K˗) bins

in preparation 𝜒 contribution

See YS talk by J.Zonneveld

7 Katya Govorkova Moriond EW 2019 21 March 2019

Analyses strategy

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

Using 2015 (0.3 fb-1) and 2016 (1.6 fb-1) data measure 𝜚s , |λ| and

ΔΓs and Γs - ΓB⁰

to test the Heavy Quark Expansion prediction of Γs / ΓB⁰ = 1.0006 ± 0.0025

ΓH - ΓB⁰

since the final state is almost entirely CP-odd Simultaneous fit to the decay time and three helicity angles

1000 1020 1040 ]

2

c [MeV/ )

−

K

+

m(K 2000 4000 6000 8000 10000 )

2

c Weighted cands. / (0.6 MeV/ LHCb

LHCb Preliminary

and m(π˖π˗) in 6 m(K˖K˗) bins

in preparation 𝜒 contribution

See YS talk by J.Zonneveld

[GeV]

π π

m

0.5 1 1.5 2

Yields/ (15 MeV)

1 10

2

10

3

10

LHCb

Data and fit (980) f (1500) f (1790) f (1270)

2

f '(1525)

2

f NR

8 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Moriond EW 2019 21 March 2019

Measurement of φs

Selection efficiency (Ω)

9 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging

Moriond EW 2019 21 March 2019

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Measurement of φs

Selection Selection efficiency (Ω)

10 Katya Govorkova

Selection and mass fit

Moriond EW 2019 21 March 2019

Boosted decision tree is trained to select signal candidates B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

10 Katya Govorkova

Selection and mass fit

Moriond EW 2019 21 March 2019

5200 5300 5400 5500 ]

2

c [MeV/ )

−

K

+

K ψ m(J/ 2000 4000 6000 8000 10000 12000 14000 16000 18000 )

2

c Weighted cands. / (2.5 MeV/ LHCb Total Signal Background LHCb Preliminary

Boosted decision tree is trained to select signal candidates Injected negative weighted MC to subtract Λb → J/ψ p K background Signal width is a function of per-candidate mass error to account for correlation with cos(θµ) B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

N(B⁰s →J/ψ K˖K˗) ≃ 117 000

10 Katya Govorkova

Selection and mass fit

Moriond EW 2019 21 March 2019

5200 5300 5400 5500 ]

2

c [MeV/ )

−

K

+

K ψ m(J/ 2000 4000 6000 8000 10000 12000 14000 16000 18000 )

2

c Weighted cands. / (2.5 MeV/ LHCb Total Signal Background LHCb Preliminary

Boosted decision tree is trained to select signal candidates Injected negative weighted MC to subtract Λb → J/ψ p K background Signal width is a function of per-candidate mass error to account for correlation with cos(θµ) Use the wrong sign (WS) combination (π±π±) to determine the shape of the combinatorial background B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530 ) [MeV] π π ψ / J ( m

5300 5400 5500

Combinations /(5 MeV)

1000 2000 3000 4000 5000 6000 7000 8000 9000

LHCb

RS data and fit π π ψ / J →

s

B π π ψ / J → B Physics background Combinatorial background WS data and fit

N(B⁰s →J/ψ K˖K˗) ≃ 117 000 N(B⁰s →J/ψ π˖π˗) ≃ 33 530

11 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging

Moriond EW 2019 21 March 2019

Measurement of φs

Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Selection efficiency (Ω)

12 Katya Govorkova

Decay time resolution

Moriond EW 2019 21 March 2019

0.5

[ps] t

2

10

3

10

4

10

5

10

6

10

Events / ( 0.015 ps ) LHCb Data Total fit Resolution 1 Resolution 2 Resolution 3 Wrong PV Long lived 1 Long lived 2

0.05 0.1 0.15

[ps]

t

δ

0.05 0.1

[ps]

eff

σ LHCb

LHCb Preliminary LHCb Preliminary

Per-candidate decay time error is calibrated using prompt J/ψ sample

σeff = 45.5 fs σeff = 41.5 fs

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

In each bin of δt perform fit for σeff

13 Katya Govorkova

Decay time efficiency Selection efficiency (Ω) Decay time resolution Flavour tagging

Moriond EW 2019 21 March 2019

Measurement of φs

Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

14 Katya Govorkova

Selection efficiency as a function of angles

Moriond EW 2019 21 March 2019

h- h+h- h+

Kinematic selection and detector acceptance are causing non uniform efficiency as function of decay angles B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

14 Katya Govorkova

Selection efficiency as a function of angles

Moriond EW 2019 21 March 2019

1 − 0.5 − 0.5 1

µ

θ cos

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation 1 − 0.5 − 0.5 1

K

θ cos

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation

[a.u.]

2 − 2 [rad]

h

ϕ

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation

h- h+h- h+

Kinematic selection and detector acceptance are causing non uniform efficiency as function of decay angles B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

angular distribution in MC / expected without acceptance effect fourth-order polynomial parameterisation

14 Katya Govorkova

Selection efficiency as a function of angles

Moriond EW 2019 21 March 2019

1 − 0.5 − 0.5 1

µ

θ cos

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation 1 − 0.5 − 0.5 1

K

θ cos

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation

[a.u.]

2 − 2 [rad]

h

ϕ

0.9 1 1.1 1.2

[a.u.] ε

LHCb simulation

h- h+h- h+

Kinematic selection and detector acceptance are causing non uniform efficiency as function of decay angles B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

angular distribution in MC / expected without acceptance effect fourth-order polynomial parameterisation

15 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging

Moriond EW 2019 21 March 2019

Measurement of φs

Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Selection efficiency (Ω)

16 Katya Govorkova

Decay time efficiency

Moriond EW 2019 21 March 2019

Use B⁰ →J/ψ K*(892) Fit simultaneously B⁰ data, simulation and B⁰s simulation

5250 5300 5350 ]

2

c ) [MeV/

−

π

+

K ψ J/ ( m 5000 10000 15000 20000 25000 30000 )

2

c Candidates / (1.0 MeV/ LHCb

LHCb Preliminary

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530 LHCb Preliminary

17 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging

Moriond EW 2019 21 March 2019

Measurement of φs

Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Selection efficiency (Ω)

18 Katya Govorkova

Flavour tagging

Moriond EW 2019 21 March 2019

Tagging power is given as tagging efficiency times dilution squared B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

εtag D2

D = (1 − 2ω)

, where

εtag D2 = 5.06 ± 0.38 % εtag D2 = 4.73 ± 0.34 %

Run1 ≈ 3.89 % Run1 ≈ 3.73 % Two tagging algorithms are used: opposite side and same side For each algorithm true mistag probability is calibrated assuming linear dependency with estimated one

19 Katya Govorkova

Decay time efficiency Decay time resolution Flavour tagging Selection

TD fit for 𝜚s |λ| ΔΓs Γs/H - ΓB⁰

Moriond EW 2019 21 March 2019

Measurement of φs

Selection efficiency (Ω)

20 Katya Govorkova

Fit projections for B⁰s →J/ψ K˖K˗

Moriond EW 2019 21 March 2019

LHCb Preliminary LHCb Preliminary LHCb Preliminary LHCb Preliminary

21 Katya Govorkova

CP asymmetry in B⁰s →J/ψ K˖K˗

Moriond EW 2019 21 March 2019

ACP(t) = Γ¯

B0

s→f (t) − ΓB0 s→f (t)

Γ¯

B0

s→f (t) + ΓB0 s→f (t) ∼ sin(ϕs) sin(Δmst)

[ps]

s

m Δ / π 0.3) modulo 2 − t (

0.1 0.2 0.3

Weighted Asymmetry

0.05 − 0.04 − 0.03 − 0.02 − 0.01 − 0.01 0.02 0.03 0.04 0.05

LHCb

LHCb Preliminary

22 Katya Govorkova

Fit projections for B⁰s →J/ψ π˖π˗

Moriond EW 2019 21 March 2019

π π

θ cos

1 − 0.5 − 0.5 1

Yields/ 0.05

200 400 600 800 1000

LHCb (a)

ψ / J

θ cos

1 − 0.5 − 0.5 1

Yields/ 0.05

200 400 600 800 1000 1200

LHCb (b) [GeV]

π π

m

0.5 1 1.5 2

Yields/ (15 MeV)

1 10

2

10

3

10

LHCb

Data and fit (980) f (1500) f (1790) f (1270)

2

f '(1525)

2

f NR

χ

2 − 2

rad) π Yields/ (0.1

200 400 600 800 1000

LHCb (c)

[ps] t

5 10

Yields/ (0.1 ps)

1 −

10 1 10

2

10

3

10

LHCb (d)

23 Katya Govorkova Moriond EW 2019 21 March 2019

𝜚s = −0.080 ± 0.041 ± 0.006 [rad] |λ| = 1.006 ± 0.016 ± 0.006 Γs- ΓB⁰ = −0.0041 ± 0.0024 ± 0.0015 [ps-1] ΔΓs = 0.0772 ± 0.0077 ± 0.0026 [ps-1] 𝜚s = −0.057 ± 0.060 ± 0.011 [rad] |λ| = 1.01 +0.08 ± 0.03 ΓH- ΓB⁰ = −0.050 ± 0.004 ± 0.004 [ps-1] −0.06

Results

Most precise measurement

• f 𝜚s ΔΓs Γs - ΓB⁰

New

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

24 Katya Govorkova Moriond EW 2019 21 March 2019

𝜚s = −0.040 ± 0.025 [rad] |λ| = 0.991 ± 0.010 ΔΓs = 0.0813 ± 0.0048 [ps-1] Γs- ΓB⁰ = −0.0024 ± 0.0018 [ps-1]

Combination of LHCb results

[B⁰s →J/ψ K⁺K⁻ Run 1] [B⁰s →J/ψ π⁺π⁻ Run 1] B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

+ +

[B⁰s →ψ(2S) 𝜒 ]

+

[B⁰s → Ds Ds ] [B⁰s →J/ψ K⁺K⁻ High mass Run 1]

+ + +

25 Katya Govorkova Moriond EW 2019 21 March 2019

𝜚s 0.1σ away from SM consistent with Standard Model 𝜚s 1.6σ away from 0 consistent with no CPV in interference between direct decay and after mixing |λ| consistent with 1 consistent with no direct CPV Γs/ΓB⁰ consistent with HQE prediction

Conclusions

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

𝜚s = −0.040 ± 0.025 [rad] |λ| = 0.991 ± 0.010 ΔΓs = 0.0813 ± 0.0048 [ps-1] Γs- ΓB⁰ = −0.0024 ± 0.0018 [ps-1]

25 Katya Govorkova

• 0.4
• 0.2
• 0.0

0.2 0.4

φc-

cs s [rad]

0.06 0.08 0.10 0.12 0.14

∆ Γ s[ps−1]

ATLAS 19.2 fb−1 D0 8 fb−1 CMS 19.7 fb−1 CDF 9.6 fb−1 Combined LHCb 4.9 fb−1

SM

68% CL contours (∆ log L = 1.15)

HFLAV Preliminary

Spring 2019

Moriond EW 2019 21 March 2019

𝜚s 0.1σ away from SM consistent with Standard Model 𝜚s 1.6σ away from 0 consistent with no CPV in interference between direct decay and after mixing |λ| consistent with 1 consistent with no direct CPV Γs/ΓB⁰ consistent with HQE prediction

Conclusions

B⁰s →J/ψ K˖K˗

[LHCB-PAPER-2019-013]

B⁰s →J/ψ π˖π˗

arXiv:1903.05530

𝜚s = −0.040 ± 0.025 [rad] |λ| = 0.991 ± 0.010 ΔΓs = 0.0813 ± 0.0048 [ps-1] Γs- ΓB⁰ = −0.0024 ± 0.0018 [ps-1]

Backup

26 Katya Govorkova Moriond EW 2019 21 March 2019

27 Katya Govorkova Moriond EW 2019 21 March 2019

Fit result B⁰s →J/ψ K˖K˗

28 Katya Govorkova Moriond EW 2019 21 March 2019

Systematics for B⁰s →J/ψ K˖K˗

29 Katya Govorkova Moriond EW 2019 21 March 2019

Fit result B⁰s →J/ψ π˖π˗

30 Katya Govorkova Moriond EW 2019 21 March 2019

Systematics for B⁰s →J/ψ π˖π˗

31 Katya Govorkova Moriond EW 2019 21 March 2019

Decay time acceptance

Decay time acceptance is approximately: Given a parameterisation of Γd around the used value Γd0 = 1/1.520ps-1

32 Katya Govorkova

Details on the B⁰s →J/ψ K˖K˗ mass model

86th LHCb Week 5 December 2017

Signal model: Double-sided Crystal Ball function (CB2) with per-event mass error used as conditional observable Quadratic dependence on the per-event mass error: σ = s1σi + s2σi2 (s1~0.8; s2~0.05)

• Tails of the CB2 are fixed from the fit to MC
• Fit in 6 m(K˖K˗) bins [990, 1008, 1016, 1020, 1024, 1032, 1050] MeV/c2

Background: Exponential for the combinatorial and gaussian for the B⁰ →J/ψ K˖K˗ contribution

Run 1 |cos(θµ)|<0.25 Run 1 |cos(θµ)|>0.7 Run 1 0.25<|cos(θµ)|<0.7

Why? To take into account this correlation. Mass resolution comes from the angles between muons, therefore per-candidate mass error and cos(θµ) are highly correlated

33 Katya Govorkova

Flavour tagging

s b

J/ψ

𝜚

μ˗ μ˖ K˖

b q

Physics@Veldhoven 22 January 2019

K˗

B± Bs Bs

? ?

Opposite side tagging

34 Katya Govorkova

Flavour tagging Bs Bs

s b q s

? ?

J/ψ

𝜚

b q

Physics@Veldhoven 22 January 2019

μ˗ μ˖ K˖ K˗

K±

Same side tagging

35 Katya Govorkova

Flavour tagging calibration

OS tagger calibrated using B+ →J/ψ K+ decays SSK tagger calibrated using B⁰s → D-s π+ decays

Moriond EW 2019 21 March 2019

Two tagging algorithms are used: opposite side and same side For each algorithm true mistag probability is calibrated assuming linear dependency with estimated one

LHCb Preliminary LHCb Preliminary

36 Katya Govorkova

PDF for data fit

Moriond EW 2019 21 March 2019

37 Katya Govorkova

PDF for data fit

Moriond EW 2019 21 March 2019

38 Katya Govorkova

Decay time efficiency B⁰s →J/ψ K˖K˗

Moriond EW 2019 21 March 2019

LHCb Preliminary LHCb Preliminary LHCb Preliminary LHCb Preliminary

39 Katya Govorkova

Future

Moriond EW 2019 21 March 2019

Comparison of φs sensitivity from different decay modes

5 23 300 Integrated Luminosity [fb−1] 0.1 1 10 100 1000 σstat(φccs

s ) [mrad] LHCb

B0

s → ψ(2S)φ

B0

s → D− s D+ s

B0

s → J/ψK+K− high mass

B0

s → J/ψππ

B0

s → J/ψφ

B0

s all ccs

φs central value [CKMFitter Summer 2016]