Measurement of the CKM angle charm mixing and … of the CKM angle g charm mixing and CP violation...
Transcript of Measurement of the CKM angle charm mixing and … of the CKM angle g charm mixing and CP violation...
Measurement of the CKM angle g charm mixing and CP violation at LHCb
Outline: LHCb detector & data taking Measurements of CKM angle g Determination of D0-D0 mixing and CP violation parameters Summary
Pavel Krokovnyon behalf of the LHCb Collaboration
Budker INP & Novosibirsk University
28 May HQL 2018 Yamagata
LHCb Experiment
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LHCb dataset Good tracking performance: momentum uncertainty 0.5-1.0%
Excellent vertexing: IP resolution (15+29/pT) mm Acceptance: 2 < η < 5
2.0 fb-1 @ 8 TeV
1.0 fb-1 @ 7 TeV
3Int. J. Mod. Phys. A30 (2015) 1530022
LHCb detector asymmetries
Measure raw asymmetries
4Int. J. Mod. Phys. A30 (2015) 1530022
N (x)−N ( x)N (x )+N (x )
CP asymmetry, detector asymmetry,production asymmetry
sum of
Sources of detector asymmetry:● Magnet sweeps opposite-charged particles
in different directions (detector not perfectly
symmetric)
● Different cross section of nuclear
interactions for particles and antiparticles
Solutions:● Regularly reverse polarity. Fiducial cuts to
remove most asymmetric regions
● Irreducible: measure in control
channels
Unitarity Triangleg is the least well constrained angle of the unitarity triangleNon-trivial triangle - CP-violationNot a triangle - Beyond SM Physics
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How to measure gTwo amplitudes b→cW(us) [B-→D0K-] and b→uW(cs) [B-→D0K-] give same final state when both D and D decay to a common final state.No penguin contribution theoretically clean.⇒
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● Amplitude ratios: ● Strong phases:
rB, r
D
dB, d
D
Experimental methods● GLW (Gronau, London, Wyler) [1991]: D→K+K-, p+p-
● ADS (Atwood, Dunietz, Soni) [1997,2001]: D→K+p-
● GGSZ (Giri, Grossman, Soer, Zupan) [2003]: D→K0Sp+p-
Dalitz plot DKS
0p+p- ds(m+
2, m-2) ~ |A|2dm
+2 dm
-2, m
±2 = m2(K
S0p±),
D0 amplitude: AD(m
+2, m
-2), D0 amplitude: A
D(m
-2, m
+2)
Amplitude of DKS
0p+p- from B+DK+ :
A
D(m
+2,m
-2) + r
BeidB + ig A
D(m
-2,m
+2)
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ΑCP=Γ(B−→DCP K−
)−Γ(B+→DCP K+
)
Γ(B−→DCP K−
)+Γ(B+→DCP K+
)=
2 r Bsin (δ B+δ D)sin γ
1+rB2+2 r B cos(δ B+δ D)cos γ
ΑCP=Γ(B−→[K+
p - ]K− )−Γ(B+→[K - p+ ]K + )
Γ(B−→[K +p - ]K−
)+Γ(B+→[K - p+]K+
)=
2 r Br D sin(δB+δD)sin γ
r B2+r D
2+2 r Br D cos (δB+δD)cos γ
ADS: B±→D(*)K± and B±→D(*)π±
8Physics Letters B 777 (2018) 16-30
GLW: B±→D(*)K± and B±→D(*)π±
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Physics Letters B 777 (2018) 16-30
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV2.0 fb-1 @ √s=13TeV
RCP
= 0.989 ± 0.013 ± 0.010
ACP
=+0.124 ±0.012 ±0.002
A = ACP
+Adet
+Aprod
Results: B±→D(*)K± and B±→D(*)π±
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Physics Letters B 777 (2018) 16-30
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV2.0 fb-1 @ √s=13TeV
B±→DK*±
11JHEP 11 (2017) 156
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV1.8 fb-1 @ √s=13TeV
ADS: B±→DK*±
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JHEP 11 (2017) 156
GLW: B±→DK*±
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JHEP 11 (2017) 156
Results: B±→DK*±
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JHEP 11 (2017) 156
RCP+
= 1.18 ± 0.08 ± 0.02
ACP+
= +0.08 ± 0.06 ± 0.01
RkpADS
= 0.0011 ± 0.004 ± 0.001
AkpADS
= -0.81 ± 0.17 ± 0.04
RkpppADS
= 0.0011 ± 0.005 ± 0.003
AkpppADS
= -0.45 ± 0.21 ± 0.14
GGSZ method
15LHCb paper 2018-017
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV2.0 fb-1 @ √s=13TeV
x± ≡ r
B cos(d
B ± g) and y
± = r
B sin(d
B ± g)
GGSZ results
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LHCb paper 2018-017PRELIMINARY
PRELIMINARY
PRELIMINARY
Measurement of CP violation in B0→D∓p±
17arXiv:1805.03448
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV
Measurement of CP violation in B0→D∓p±
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arXiv:1805.03448
Measurement of CP violation in B0→D∓p±
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arXiv:1805.03448
g combination
20LHCb CONF 2018-002
g combination
21LHCb CONF 2018-002
Bs0→D
s∓K± time-dep
B0→DK*0
B0→DK+p-
B0→D∓p± time-dep
B+→DK+
B+→D*K+
B+→DK*+
B+→DK+p+p-
D0-D0 mixing and CP violation in D0→K+π−
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Right-sign (RS) D0→K-π+ is dominated by CF decay
Wrong-sign (WS) D0→K+π-
has two sources:
Mixing amplitude is time-dependent
Ratio R(t) = ΓWS
(t)/ΓRS
(t) depends on x and y:
R( t)=RD+√RD y '(
tτ )+
x' 2+ y ' 2
4(
tτ )
2
( x 'y ')=(
cosd sin d−sin d cos d)(
xy )
R±(t)=RD
±+√RD
± y '±(
tτ )+
x '±2+ y '±2
4(
tτ )
2 ICPV: x’+ ≠ x’−
and/or y’+ ≠ y’−
DCPV: RD
+ ≠ RD
-
D0-D0 mixing and CP violation by D0→K+π−
23Phys Rev D97, 031101 (2018)
177 106
RS events 0.72 106
WS events
Dataset:1.0 fb-1 @ √s=7 TeV2.0 fb-1 @ √s=8 TeV2.0 fb-1 @ √s=13TeV
D0-D0 mixing and CP violation by D0→K+π−
24Phys Rev D97, 031101 (2018)
D0-D0 mixing and CP violation by D0→K+π−
25Phys Rev D97, 031101 (2018)
RD = 3.454 ± 0.028 ± 0.014
y` = 5.28 ± 0.45 ± 0.27x`2 = 0.039 ± 0.023 ± 0.014
RD = 3.454 ± 0.028 ± 0.014
y`+ = 5.01 ± 0.48 ± 0.29(x`+)2 = 0.061 ± 0.026 ± 0.016y`- = 5.54 ± 0.48 ± 0.29(x`-)2 = 0.016 ± 0.026 ± 0.016
RD
+ = 3.454 ± 0.040 ± 0.020y`+ = 5.01 ± 0.64 ± 0.38(x`+)2 = 0.061 ± 0.032 ± 0.019R
D- = 3.454 ± 0.040 ± 0.020
y`- = 5.54 ± 0.64 ± 0.38(x`-)2 = 0.016 ± 0.033 ± 0.020
AD= (−0.1 ± 9.1)×10−3
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Conclusion LHCb continue efforts to measure CKM angle g.
Combined result is still limited by statistics.
Further progress expected after LHCb upgrade. Most precisest
GGSZ method requires preciest measurement of strong phase
difference δD on D0→K
S0p+p- Dalitz plot BES III can do it. ⇒
D0-D0 mixing parameters have been measured in D0→K+π−. CP
violation is found consistent with zero.
Further results are expected. Please see LHCb upgrade talk by
Preema Pais on Friday.
g=(74.0−5.8+5.0 )o
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Backup
Search for CP asymmetry in B-→D- D0
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LHCb paper 2018-007
Submitted to JHEP
Dataset:2.0 fb-1 @ √s=7 TeV1.0 fb-1 @ √s=8 TeV
Interference in B→ DK
● No penguin contribution ⇒theoretically clean
● The only CP-violating parameter that can be measured solely in tree-level processes
● g precision is limited by small branching ratios
Best theoretically clean way of measuring g is based on interference between b→cus and b→ucs tree level amplitudes. E.g., B±→DK± followed by D→f and B→DK± followed by D→f, where f is a common final state
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Atwood-Dunietz-Soni method
30PRL 78, 3357 (1997);
PRD 63, 036005 (2001)D. Atwood, I. Dunietz and A. Soni,
Doubly Cabibbo suppressed (DCS) D decays can be used tomeasure g. E.g. [K-p+]K- can be reached in two ways:● Cabibbo favored (CF) B-→D0K- followed by DCS D0→K+p-
● DCS B-→D0K- followed by CF D0→K+p-
Gronau-London-Wyler method
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СР eigenstate of D-meson is used (DCP).
CP-even : DCP K+K–, π+ π –
RCP=Br (B→DCP K ) /Br (B→DCP π )
Br (B→D0 K ) /Br (B→D0 π )=1+r B
2 +2 rB cos δ cos γ
Double ratio:
ΑCP=Br (B−
→DCP K−)−Br (B+
→DCP K+)
Br (B−→DCP K−
)+Br (B+→DCP K+
)=
2 rB sin δ sin γ
1+r B2 +2 r Bcos δ cos γ
СР-asymmetry:
2 equations, 3 unknowns ),,( gdBr
[Phys. Lett. B 253 (1991) 483][Phys. Lett. B 265 (1991) 172]
g
g
Dalitz method
32[A. Bondar, unpublished (2002)][A. Giri, Yu. Grossman, A. Sofer, J. Zupan, PRD 68, 054018 (2003)]
Information from Dalitz plot analysis of DKS
0p+p- from B±->DK±
Dalitz plot density: ds(m+
2, m-2) ~ |A|2dm
+2dm
-2, where m
±2 = m2(K
S0p±)
Flavour D amplitude: AD(m
+2, m
-2)
CP -conservation in DKS
0p+p- decays: AD(m
+2, m
-2) = A
D(m
-2, m
+2)
Amplitude of DKS
0p+p- from B+DK+ :
AB (m
+2, m
-2) = A
D (m
+2, m
-2) + r
BeidB + ig A
D(m
-2, m
+2) =
Required to know phase diference between AD(m+2, m-
2) and AD(m-
2, m+2). Taken from e+e-DD (CLEOc)
GGSZ method
33[A. Giri, Yu. Grossman, A. Sofer, J. Zupan, PRD 68, 054018 (2003)]
)](2[ 2iiiiiBiBi ysxcKKKrKhN
Number of events in B-plotNumber of events in D0-plot: Ki
C (m+2 , m−
2)=cos( δD(m+
2 , m−2)−δ D(m−
2 ,m+2))
S (m+2 , m−
2)=sin (δD(m+
2 ,m−2)−δD(m−
2 , m+2))
PCP±(m+2 ,m−
2)=|f D± f̄ D|
2=PD+ P̄D±2√PD P̄D C
PCorr(m+2 , m−
2 , m+' 2 , m−
' 2)=|f D f̄ D'− f̄ D f D
'|2=
=PD P̄D'+ P̄D PD
'−2√PD P̄D PD
' P̄D'(C C'
+S S')
DCPKSπ+π–:
ψ(3770)(KSπ+π–)D (KSπ+π–)D :
where)cos( 3d Brx
y±=r Bsin (δ±ϕ3 )Free parameters
g combination
34LHCb CONF 2018-002
g combination
35LHCb CONF 2018-002
GGSZ systematic uncertainties
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LHCb paper 2018-017
D0-D0 mixing and CP violation by D0→K+π−
37Phys Rev D97, 031101 (2018)
Interference in B→ DK
Neglible theoretical uncertainty (Zupan and Brod 2013)Theory uncertainty on ~10-7 - [arXiv:1308.5663]
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