CKM angle gmeasurement at LHCb 04.06.pdf · PRL 78 3257 (1997) PRD 63 036005 (2001) PRD 68 054018...
Transcript of CKM angle gmeasurement at LHCb 04.06.pdf · PRL 78 3257 (1997) PRD 63 036005 (2001) PRD 68 054018...
CKM angle g measurement
at LHCb
Susan Haines
University of Cambridge
on behalf of
the LHCb collaboration
LHCP 2018
Susan Haines 2
CKM angle g
▪ Least well measured Unitarity Triangle angle
▪ Can measure at tree level with 𝐵 → 𝐷𝑋 decays
▪ Exploit weak phase difference g between 𝑏 → 𝑢 and 𝑏 → 𝑐 transitions
▪ Theoretically clean but room for NP JHEP 01 (2014) 051 PRD 92 033002 (2015)
Susan Haines 3
▪ At LHCb, perform
▪ time-integrated measurements
𝐵− → 𝐷(∗)𝐾(∗)−, 𝐵0 → 𝐷𝐾∗0, 𝐵0 → 𝐷𝐾+𝜋−, 𝐵− → 𝐷𝐾−𝜋+𝜋−
▪ GLW analysis (𝐷 → 𝐶𝑃 eigenstate)
▪ ADS analysis (𝐷 → flavour specific)
▪ GGSZ analysis (𝐷 → multibody)
▪ Dalitz analysis (𝐵 → multibody)
▪ time-dependent measurements
𝐵𝑠0 → 𝐷𝑠
∓𝐾±, 𝐵0 → 𝐷∓𝜋±
▪ combination of LHCb g measurements
PLB 557 198 (2003)
PLB 253 483 (1991) PLB 265 172 (1991)
PRL 78 3257 (1997) PRD 63 036005 (2001)
PRD 68 054018 (2003) PRD 70 072003 (2004)
PRD 79 051301(R) (2009) PRD 80 092002 (2009)
PRD 37 3186 (1988) ZPC 54 653 (1992) NPB 671 459 (2003)
Susan Haines 4
The LHCb experiment
▪ Designed for study of particles containing 𝑏 or 𝑐
▪ High precision tracking and vertexing
▪ Momentum resolution 0.5 − 1.0 %
▪ Impact parameter resolution (15 + 29 / 𝑝𝑇) 𝜇m
▪ RICH detectors for hadron PID (𝐾 − 𝜋 separation)
JINST 3 S08005 (2008)
2 < 𝜂 < 5
▪ Determine g using 𝐷 decay to three-body self-conjugate 𝐾𝑆
0𝜋+𝜋− or 𝐾𝑆0𝐾+𝐾− final state
▪ One solution for g in [0, p]
▪ Requires knowledge of resonant structure of 𝐷 → 𝐾𝑆
0ℎ+ℎ− decay across phase space
▪ Observables: 𝑥± = 𝑟𝐵cos(𝛿𝐵 ± 𝛾), 𝑦± = 𝑟𝐵sin(𝛿𝐵 ± 𝛾)
PRELIMINARY
RUN 2PRELIMINARY
RUN 2
Susan Haines 5
GGSZ analysis of𝑩−→ 𝑫𝑲−, 𝑫 → 𝑲𝑺𝟎𝒉+𝒉−
𝐴𝐵+ ∝ ҧ𝐴𝑓 + 𝑟𝐵𝑒𝑖(𝛿𝐵+𝛾)𝐴𝑓
𝐴𝐵− ∝ 𝐴𝑓 + 𝑟𝐵𝑒)𝑖(𝛿𝐵−𝛾 ҧ𝐴𝑓
𝐵−𝐵+
LHCb-PAPER-2018-017
In preparation
▪ Model-independent method: bin 𝐷 decay phase
space according to 𝐷0 − ഥ𝐷0 strong phase
difference
▪ Yield in bin 𝑖
▪ (𝑐𝑖 , 𝑠𝑖) strong phase difference measurements from
CLEO-c
Susan Haines 6
LHCb-PAPER-2018-017
In preparation
PRD 82 112006 (2010)
𝑁±𝑖+ = ℎ𝐵+ 𝐹∓𝑖 + 𝑥+
2 + 𝑦+2 𝐹±𝑖 + 2 𝐹𝑖𝐹−𝑖 𝑥+𝑐±𝑖 − 𝑦+𝑠±𝑖
𝑁±𝑖− = ℎ𝐵− 𝐹±𝑖 + 𝑥−
2 + 𝑦−2 𝐹∓𝑖 + 2 𝐹𝑖𝐹−𝑖 𝑥−𝑐±𝑖 + 𝑦−𝑠±𝑖
2𝑁 bins (𝑖 ∈ [−𝑁,𝑁], 𝑖 ≠ 0)
𝑖 > 0 for 𝑚−2 > 𝑚+
2
▪ Results with Run 2 data (2 fb-1 at 𝑠 = 13 TeV):
Susan Haines 7
Statistical
uncertainties
only
LHCb-PAPER-2018-017
In preparation
PRELIMINARY
2 fb-1 at 𝑠 = 13 TeV
PRELIMINARY
𝑥− = (9.0 ± 1.7 ± 0.7 ± 0.4) × 10−2
𝑦− = (2.1 ± 2.2 ± 0.5 ± 1.1) × 10−2
𝑥+ = (−7.7 ± 1.9 ± 0.7 ± 0.4) × 10−2
𝑦+ = (−1.0 ± 1.9 ± 0.4 ± 0.9) × 10−2
First observation
of 𝐶𝑃 violation in
𝐵−→ 𝐷𝐾−,𝐷 → 𝐾𝑆
0ℎ+ℎ−
▪ Combine with Run 1 results (3 fb-1 at 𝑠 = 7,8TeV) to give constraint on g:
Susan Haines 8
GGSZ, PRELIMINARY
𝛾 = 80−9+10 °
LHCb-PAPER-2018-017
In preparation
GGSZ
PRELIMINARY
GGSZ
PRELIMINARY
JHEP 10 (2014) 097
▪ Phase difference of (2𝛽 + 𝛾) between direct 𝐵0
decay and decay after oscillation
▪ Measure decay-time-dependent 𝐶𝑃 asymmetries using decay rates as function of tagged 𝐵0/ ത𝐵0
decay time
▪ Fix 𝐶𝑓 = −𝐶 ҧ𝑓 = 1 in fit; constrain Δ𝑚 and Γ
Susan Haines 9
Time-dependent analysis of 𝑩𝟎 → 𝑫∓𝝅±arXiv:1805.03448
Γ𝐵0→𝑓(𝑡) ∝ 𝑒−Γ𝑡[1 + 𝐶𝑓 cos Δ𝑚𝑡 − 𝑆𝑓 sin Δ𝑚𝑡 ]
Γ𝐵0→ ҧ𝑓(𝑡) ∝ 𝑒−Γ𝑡[1 + 𝐶 ҧ𝑓 cos Δ𝑚𝑡 − 𝑆 ҧ𝑓 sin Δ𝑚𝑡 ]
HFLAVEPJ C 76 412 (2016)
Assume
𝑞/𝑝 = 1and ΔΓ = 0
𝐶𝑓 =1 − 𝑟𝐷𝜋
2
1 + 𝑟𝐷𝜋2 = −𝐶 ҧ𝑓 𝑆𝑓 = −
]2𝑟𝐷𝜋sin[𝛿 − 2𝛽 + 𝛾
1 + 𝑟𝐷𝜋2 𝑆 ҧ𝑓 =
]2𝑟𝐷𝜋sin[𝛿 + 2𝛽 + 𝛾
1 + 𝑟𝐷𝜋2
▪ Analysis with 3 fb-1 at 𝑠 = 7,8 TeV
Susan Haines 10
arXiv:1805.03448
𝑆𝑓 = 0.058 ± 0.020 ± 0.011
𝑆 ҧ𝑓 = 0.038 ± 0.020 ± 0.007
𝛾 ∈ [5,86]° ∪ [185,266]°
𝑁𝑠𝑖𝑔 = 479000 ± 700
▪ First measurements at
hadron collider
▪ Agree with, and more precise
than, previous measurementsPRD 73 111101(R) (2006) PRD 73 092003 (2006)
Susan Haines 11
Combination of LHCb measurements▪ Combine tree-level LHCb g measurements:
▪ Frequentist approach
▪ Auxiliary inputs from HFLAV, CLEO and LHCb
LHCb-CONF-2018-002
Susan Haines 12
▪ Most precise determination of g from a single
experiment
▪ World average: 𝛾 = 73.5−5.1+4.2 °
▪
LHCb-CONF-2018-002
PRELIMINARY
𝛾 = 74.0−5.8+5.0 °
HFLAV
Susan Haines 13
Future g decay modes:
𝑩(𝒔)𝟎 → ഥ𝑫(∗)𝟎𝝓 and 𝑩(𝒔)
𝟎 → ഥ𝑫𝟎𝑲+𝑲−
▪ Possible future measurements of
▪ g with 𝐵𝑠0 → 𝐷𝜙
▪ g (and 𝜙𝑠) with time-dependent Dalitz plot analysis of
𝐵𝑠0 → 𝐷𝐶𝑃𝐾
+𝐾−
▪ NEW branching fraction measurements and limits
with 3 fb-1 at 𝑠 = 7,8 TeV
PRD 85 114015 (2012)
LHCb-PAPER-2018-014
LHCb-PAPER-2018-015
In preparationNEW
Susan Haines 14
PRELIMINARY
PRELIMINARY
ℬ 𝐵𝑠0 → ഥ𝐷0𝜙 = (3.0 ± 0.3 ± 0.3 ± 0.2) × 10−5
ℬ 𝐵𝑠0 → ഥ𝐷∗0𝜙 = (3.8 ± 0.5 ± 0.3 ± 0.2) × 10−5
ℬ 𝐵0 → ഥ𝐷0𝜙 < 2.0 × 10−6 (@ 90% 𝐶. 𝐿. )
FIRST OBSERVATION
MOST PRECISE
BEST LIMIT
ℬ 𝐵0 → ഥ𝐷0𝐾+𝐾− = (6.1 ± 0.4 ± 0.3 ± 0.3) × 10−5
MOST PRECISE
ℬ 𝐵𝑠0 → ഥ𝐷0𝐾+𝐾− = (5.7 ± 0.5 ± 0.5 ± 0.5) × 10−5
FIRST OBSERVATION
LHCb-PAPER-2018-014
LHCb-PAPER-2018-015
In preparationNEW
PRELIMINARY
Susan Haines 15
▪ Combination of LHCb results gives most precise
determination of g from a single experiment
▪ Covered most recent results and updated
combination here
▪ Coming soon:
▪ studies of new decay modes
▪ further updates including Run 2 data set
Conclusions and prospects
PRELIMINARY
𝛾 = 74.0−5.8+5.0 °
Susan Haines 16
Backup:
GGSZ analysis of 𝑩−→ 𝑫𝑲−, 𝑫 → 𝑲𝑺𝟎𝒉+𝒉−
LHCb-PAPER-2018-017
In preparation
𝐵−𝐵+
PRELIMINARY PRELIMINARY
𝐾𝑆0 without
VELO (Si
vertex tracker)
daughter hits
𝐾𝑆0 with VELO
(Si vertex
tracker)
daughter hits
𝐵− → 𝐷ℎ−,𝐷 → 𝐾𝑆
0𝜋+𝜋−
PRELIMINARYPRELIMINARY
PRELIMINARY PRELIMINARY
Susan Haines 17
LHCb-PAPER-2018-017
In preparation
𝐵−𝐵+
PRELIMINARY PRELIMINARY
𝐾𝑆0 without
VELO (Si
vertex tracker)
daughter hits
𝐾𝑆0 with VELO
(Si vertex tracker)
daughter hits
𝐵− → 𝐷ℎ−,𝐷 → 𝐾𝑆
0𝐾+𝐾−
PRELIMINARY PRELIMINARY
PRELIMINARY PRELIMINARY
Susan Haines 18
Backup:
Time-dependent analysis of 𝑩𝟎 → 𝑫∓𝝅±
arXiv:1805.03448
Susan Haines 19
Backup:
Combination of LHCb measurements
LHCb-CONF-2018-002
Susan Haines 20
Backup:
𝑩(𝒔)𝟎 → ഥ𝑫(∗)𝟎𝝓 and 𝑩(𝒔)
𝟎 → ഥ𝑫𝟎𝑲+𝑲−
𝐵0 → ഥ𝐷0𝐾+𝐾−
PRELIMINARY
𝐵𝑠0 → ഥ𝐷0𝐾+𝐾−
PRELIMINARY
LHCb-PAPER-2018-014
LHCb-PAPER-2018-015
In preparationNEW