CP violation in mixing at LHCb
CP violation in mixing at LHCb
J.A. de Vries
on behalf of the LHCb collaboration
OUTLINE
•
Introduction
• asl
d (2015)
• asl
s (new
result)
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
2
CPV IN MIXING
Neutral mesons: mass eigenstates vs flavour
eigenstates
↵
•
|BH,L i = p |Bi ± q B̄
Mixing due to
•
,
m
q
q
CP violation in mixing:
•
P(B ! B̄) 6= P(B̄ ! B)
•
|q/p| =
6 1
m ⇡ 18 ps 1
⌧ ⇡ 1.5 ps
(Bs0 system)
So far only observed in kaon system:
(εK = 0.2%)
PDG, Chin. Phys. C, 38, 090001 (2014)
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
3
on
CPV IN MIXING
ing means that the probability that a B mixes into a B is di↵erent
that a B mixes into a B. The flavour specific or “semileptonic”
P(Bq ! B̄q ) 6= P(B̄q ! Bq )
as • CP Violation in mixing:
aqsl
P (B q ! Bq ) P (Bq ! B q )
=
,
P (B q ! Bq ) + P (Bq ! B q )
1 |q/p|4
=
⇡
4
1 + |q/p|
(q = d, s)
q
mq
tan(
(1)12
q )
Lenz, Nierste [JHEP 0706:072 (2007)]
distinguishing the two species of neutral B mesons, namely the
ndard
Model predictions
[1, 2] arefinal
tiny state
compared
to the
current
• Semileptonic
inclusive
(flavour
specific)
ty: adsl = ( 4.1 ± 0.6) ⇥ 10 4 and assl = (1.9 ± 0.3) ⇥ 10 5 . This
t of• these
asymmetries
an
excellent
null
test
of
the
Standard
Model.
2 neutral B mesons:
e dimuon asymmetry measured by D0 [3] is sensitive adsl and assl
0
+
d
B
!
D
µ
⌫
dard deviation
discrepancy
aslthe Standard Model. Dedicated
µ X with
d
sand D0 [5]. An overview of past
ave been
by⌫ LHCb
[4]
Bs0performed
! D s µ+
asl
µX
world average is provided by the Heavy Flavor Averaging Group
d averages
measurements
as of Summer 2015 (excluding
adsl of
= (pure
4.7a±sl 0.6)
⇥ 10 4
metry) are
assl = (2.22 ± 0.27) ⇥ 10 5
metries= (+0.01 ± 0.20)%
adsl
Artuso, Borissov, Lenz [arXiv:1511.09466]
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
(2)
4
MEASURING asl
‘Raw’ untagged asymmetry:
N (D µ+ ) N (D+ µ )
asl
Araw =
=
+
...
+
+
N (D µ ) + N (D µ )
Production asymmetry:
N (B̄)
N (B)
AP =
+ N (B̄)
N (B)
2
Detection asymmetry:
✏(D µ+
) ✏(D+ µ )
AD =
+
✏(D µ ) + ✏(D+ µ )
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
5
TIME DEPENDENCE
✓
N (f, t) N (f¯, t)
Araw (t) =
⇡
A
+
+
A
D
P
¯
2
N (f, t) + N (f , t)
adsl
Offset
adsl
2
◆
cos( md t)
Amplitude
Mixing
oscillation
For asld: measure offset and amplitude
to disentangle AP and asld
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
6
aslLHCb
d
3
Events / ps
×10
ents / ps
×103
340 LHCb
2
130
0
20
-1
-210
1
3
1800
×10
Data
Total fit
Signal
Comb.
Events / ( 1.4 MeV/c2 )
Events / ( 1.4 MeV/c2 )
AD + AP
Asymmetry [%]
Data
✓
◆
d
d
Total
¯, t)
− a+
N
(f,
t)
N
(
f
asl
sl
1000
D
µ
Signal
Araw (t) =
⇡
A
+
+
A
cos(
m
t)
D
P
d
2
N (f, t) + N (f¯, t)
B+ bkg. 2
Comb. bkg.
500
×103
100
LHCb
50
10
1850
1900
mK ππ [MeV/c2]
LHCb
2AP - asld
1800
t [ps]
1850
LHCb, PRL 114 (2015) 041601
1
mK
Data
200
0! D
+ ⌫ X candidates in (left) 20
Total
+
Figure 1: Distribution of mK⇡⇡ for
the
B
µ
−
µ
*
D
µ
Signal
2012
data.
Projections
of
the
fit
function
are2016
superimposed
(blue continuous 7li
J.A. de Vries - CPV in mixing at LHCb - BEAUTY
150
THE STORY SO FAR
2
HFAG [arXiv:1412.7515]
*without D0 dimuon result [PRD 89, 012002 (2014)]
LHCb:
ad
sl = ( 0.02 ± 0.19(stat) ±
assl = ( 0.06 ± 0.50(stat) ±
LHCb, PRL 114, 041601 (2015)
LHCb, PLB 728C (2014) 607
-4
-3
Ds µνX
µ
LHCb D(*)µνX
D0 D(*)µνX
BaBar D*lν
BaBar ll
Belle ll
D0
= (0.01 ± 0.20) ⇥ 10
= ( 0.48 ± 0.48) ⇥ 10
0µ
-3
2
HFAG Fall '14
D
-2
HFAG*:
adsl
assl
0
-1
Artuso, Borissov, Lenz [arXiv:1511.09466]
Standard Model
Ds µνX
adsl = ( 4.7 ± 0.6) ⇥ 10 4
assl = (2.22 ± 0.27) ⇥ 10 5
1
LHCb
asls [%]
SM:
-2
-1
0
1
asld [%]
FIG. 15 Overview of measurements in the adsl assl plane. Direct
measurements of assl and adsl listed in Tab. V (B 0 average as
the vertical band, Bs0 average as the horizontal band, D0 dimuon result as the yellow ellipse). The black point close to
0.30(syst))%
-1
(0; 0) is the Standard Model
prediction
of Ref. (Lenz and
1
fb
0.36(syst))%
Nierste, 2011) with error bars multiplied by 10. The plot is
an updated version of the plot from Ref. (Aaij et al., 2015f),
including the result from Ref. (Lees et al., 2015b).
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
8
LHCb-PAPER-2016-013
New
s
asl
- 3/fb
resul
t!
(Ds µ+ X)
(Ds+ µ X)
assl
⇡
,
(Ds µ+ X) + (Ds+ µ X)
2
OVERVIEW
(2)
e↵ect of the Bs0 production is diluted by a factor 5 ⇥ 10 4 and thus
+ µ ⌫ asXthe di↵erence between the number
(observed)
asymmetry
• Inclusive
easured
with
B 0s ! isDdefined
µ
s
positive and negative muons,
•
+
+
N (D
µ
X)
N
(D
X)
Untagged,
time-integrated
analysis:
s
s µ
. ◆Z
(3)
✓+
s
N (Ds
N
(D
µ
X)
asl
asl
s
Araw ⇡ AD +
+ AP
cos( ms t)dt
is a↵ected by detection asymmetries
(AD ) and
2
2 background asymmetries
O(10-4)
Araw =
s
µ+ X) +
assl
Araw = (1 fbkg ) + fbkg Abkg + AD ,
(4)1
m ⇡ 18 ps
2
⌧ ⇡ 1.5 ps
action
of background
and Abkg the corresponding asymmetry. Hence,
• Adding
backgrounds:
assl
1
=
(Araw
2
1 fbkg
AD
fbkg Abkg ) .
(5)
also be written as
assl
=
Nsig + Nbkg
N
bkg
J.A.
de
Vries
CPV
in
mixing
at
LHCbA
- BEAUTY 2016
(A
A )
,
(6)
10
LHCb-PAPER-2016-013
← φπ
2
LHCb preliminary
LHCb
±
±
Ds → K K π
2
±
103
1.5
1
±
π ±)
NR
m2(K
Various levels of
backgrounds in M(Ds-).
Regions treated separately.
2.5
±
3 Dalitz regions
[GeV / c4]
DS SELECTION
102
*
K K
m(Kπ) in [806, 986] MeV
10
0.5
1
2
±
m(KK) in [1000, 1040] MeV
3
1
m2(K ±K ) [GeV2/ c4]
Figure 1: Dalitz plot of the Ds ! K + K ⇡ decay for selected Ds µ+ candidates,
selection regions indicated. In addition, a invariant mass of the Ds candidates is
2 .at LHCb - BEAUTY 2016
de Vries
- CPV
in mixing
between 1950 J.A.
and
1990
MeV/c
11
LHCb-PAPER-2016-013
Candidates × 103 / (2.5 MeV)
DS YIELDS
150
LHCb preliminary
LHCb
D±s
D±
Comb.
100 φ π
50
1800K *K 1850
60
40
20
Minv(K
1800NR
40
1900
1850
1900
-
-
Minv(K
1950
2000
K+π+)_PhiPi
1950
(MeV)
2000
K+π+)_KStarK
(MeV)
899 x 103
413 x 103
280 x 103
20
1800
1850
1900
1950
2000
m(K +K −π ±) [MeV/ c2]
Figure 2: Invariant mass distributions for Ds± candidates in the three Dalitz regions, summed
- + and data-taking
over- both magnet polarities
periods. Overlaid is the result of the fit, with signal
s
s
and background components as indicated in the legend.
Select (D μ ), fit D mass peaks
- Directly produced Ds is removed
- Raw yield contains peaking backgrounds
141
approximated as
Adet
⇡ Atrack
+ A LHCb+- A
trig , 2016
J.A. de
Vries - CPV
in mixing atPID
BEAUTY
(4)
12
etry is a↵ected
by detection asymmetries (AD )three
andregions.
background
asymmetries
The uncertainties are correlated between the
The green horizontal band represents
2
PEAKING
BACKGROUNDS
a
ABackground
= (1 f ) asymmetry
+ f A + correction
A ,
(4)
the uncertainty on the average value of
5.8
LHCb-PAPER-2016-013
raw
bkg
s
sl
bkg
assl .
bkg
D
2
Table 2: Background
contributions
(ftheir
ratios
("sig /"bkg ) and
their e↵ective asymbkg ), efficiency
3
The
background
contributions
and
e↵ective
production
asymmetries
are
e fraction
of
background
and
A
the
corresponding
asymmetry.
Hence,
Peaking
backgrounds
dilute
and
bias
the
measurement
bkg are obtained from the
metries. The branching fractions
+ PDG [16]. The signal branching ratio
4
Table 12.
Note that the double D and B ! Ds KX
backgrounds
have
opposi
s B = (7.9 ± 2.4)%. The b-hadron fractions used are
is
f
/f
=
f
/f
=
(3.86
±
0.22)
[28] and
u s
d s
asl
1
(⇤)
(⇤)+
0
5
metries.f⇤0b=
The
symmetric
B
Dbkg
/fs = (2.34
± 0.31)
[29].
s ) .decays will have a zero
(Araw sA!
(5) asymme
D Dfsbkg A
2 contribute
1 fbkg to the dilution of the observed asymmetry. The backgrou
6
will only
7
detection-corrected
calculated
an
also
be written
as asymmetry is
Mode
B [%]
B(c ! µ)as
[%](cf.
"sigEq.
/"bkg9).fbkg /fsig [%]
Abkg [%]
+ ! D (⇤)0 D (⇤)+ X
: branching
0.4 ± 0.4
s
B
7.9 ± 1.4 N 6.5 f±bkg
0.1
4.34 ratios
5.8(PDG)
± 1.1
s
asl
Nsig + N
bkg
bkg
1
(⇤)+
0
0
=B ! D Ds X (AAraw
A±D1.2
)
A±bkg
, Dand4.08
efficiency
5.7
6.5
0.1 A
4.4
±
1.0 (6)0.18 ± 0.13
=
(A
f
A
)
,
corr
raw
bkg
bkg
2
Nsig(⇤)+
Nsig
1
f
0
bkg
B ! D Ds X
4.6 ± 1.2
16.1 ± 0.3
6.41
5.6 ± 1.5
0.18 ± 0.13
‘double-D’
0 ! D (⇤) D (⇤)+
4.5
± 1.4
8.1 ± 0.4
3.68
1.0 ± 0.3
to control Bthe
detector-related
and
background
asymmetries.
s
s
s
±
Abkgin4.51
mainly
1.4window,
(⇤)+
8
where fbkg
the
fraction
the D±sfrom
mass
and
+2.1 that is peaking
0 is
+ Dbackground
⇤
!
⇤
X
10.3
4.5
±
1.7
3.0
±
0.4
±
0.9
s
c the production asymmetry
ary measurement,
of
prompt
D
mesons
is
1.8
b
s
production
9
is the sum
fractions
e↵ective
B of!all
Ds+background
K µ ⌫X+ 0.061
± 0.010 multiplied
–with the
2.43asymmetries:
1.3 ±production
0.2
0.4 ±asym
0.4
nalysis usesB 0the
same
Ds !
KK⇡
decay mode– as
the
analsysis.
LHCb,
JHEPmain
09 177 (2014)
‘DsK’
+
0 µ ⌫X
!
D
K
0.061
±
0.010
2.89
1.1
± 0.2
0.18 ± 0.13
0
The total background
fraction and asymmetry are
be(2015)
s
S
LHCb,found
PRL 114, to
041601
ion asymmetries are mostly the same, exceptLHCb,
forChin.Phys.C
the muon
detection
40, 1, 011001(2016)
hich are only present in the main analysis.
auxiliary measurement is
fbkg /fThe
sig = (22.6 ± 7.3)%,
d in Chapter 11.
f = (18.4 ± 6.0)%,
1
where fsig
Taken
into
account:
X
bkg
ii Aii
⌃iffbkg
fbkg
0.037 ±
±0.033)%
0.028)% ,
bkgAbkg = ( 0.045
bkgAbkg
bkg = f
1
i
10
is the number of signal over the total
number of signal and backgroun
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
13
DETECTION ASYMMETRIES
Tracking
PID
Triggering
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
14
method has already been used at LHCb to me
LHCb-PAPER-2016-013
D0 ! K ⇡ + ⇡ + ⇡ . An attempt to apply the sa
but using D⇤+ with a muon tag in order to con
in Ref. [6]. This method is limited by the rela
probe particle and poor separation of signal a
the possibility
to require that the probe parti
4
suggested LHCb
in
[6],preliminary
thus restricting the problem to t
LHCb
Magnet up
3
the direction of the probe particle fixed, the p
Magnet
down and the
essentially
perfect momentum
resolution
2
0
mass peak.
This
also
allows
us
to
use
the
D
!
1
though this will only be possible with a dedicat
0
In Sect.
2, we study the expected level of nu
−1 that would not be measured with this
detector
from simulation.
Sect. 3 describes the selection
−2
20
40
60
80
100
yields.
p [GeV/ c]
TRACKING ASYMMETRY
A track (π ±) [%]
mmetries: MuPi
Largest systematic in previous analysis
Combine 2 methods:
decays of which one of the two is not
- J/ψ tag-and-probe
g track. (a)Measure
the tracking asymmetry
*
- D partially reconstructed
+ simulation studies
⇡sig
(P ( )) Atrack ( )
Figure 7: Tracking asymmetry as function of momentum p.
J/ψ method
1
0.8
Primary vertex
LHCb
0.6
0.4
0
-0.2
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
Magnet up
Magnet down
F
A PID(K ±) [%]
A PID(K ±) [%]
D0 decay vertex
0.2
(a)
VELO
(c)
2015 JINS
T-stations
(b)
Detection
asym
D method
The weighted av
methods described
in the
shownproposed
in each bin signal
with its statistical
uncertainty
Figure
1: text
Theis two
decays with
D⇤+
*+ .
(right) D0 ! K ⇡
K-
0.6
0.4
0.2
0
-0.2
U
pi
P
Ma
as
π+
π-
1
0.8
?
π+
LHCb
π+
Ma
S
st
15
LHCb-PAPER-2016-013
1
0.8
0.6
LHCb
LHCbpreliminary
⇡
A PID(K ±) [%]
A PID(K ±) [%]
PID & TRIGGER
Magnet up
Magnet down
0.4
1
0.8
0.6
0.2
0
0
-0.2
-0.2
-0.4
-0.4
5
K ⇤ K & NR
Magnet up
Magnet down
PID
0.4
0.2
0
LHCb
LHCbpreliminary
10
0
5
10
p T [GeV/ c]
p T [GeV/ c]
A det(µ ±) [%]
Trigger
A det(µ ±) [%]
Figure 8: Asymmetry of the PID requirements on the kaon as a function of transverse momentum,
pT , for (left) the ⇡ 6region, and (right) the K ⇤ K and NR regions. The
6 asymmetry is measured
Magnetselected
up
Magnet up
from a large sample of D⇤+ !LHCb
D0 (K 2011
⇡ + )⇡ + decays
without PID requirements.
LHCb 2012
LHCb
4
4
Magnet down
Magnet down
Average
Average
2
2
0
-2
-2
13
LHCb preliminary
-4
-6
0
0
5
10
15
p [GeV/ c]
T
LHCb preliminary
-4
-6
0
5
10
15
p [GeV/ c]
T
Figure 9: Combined muon PID and hardware trigger asymmetry as a function of muon transverse
J.A. de Vries
in mixing
at LHCb 2012
- BEAUTY
2016The asymmetry is measured with a 16
momentum, pT , for (left)
2011- CPV
data
and (right)
data.
013
244
246
RESULTS
This appendix contains supplementary material that will posted on the public CDS record
but will not appear in the paper.
5
4
LHCb
LHCb preliminary
LHCb
3
2
1
0
-1
-2
-3
s with their statistical and systematic
Table
of inputs to the determination
of
a
-4 1: φ πOverview
φπ
φπ
φπ
NR
NR
N
N
K*
K*
K * sl
K*
assl (× 10-2)
245
LHCb-PAPER-2016-013
R,20
R,20
,201 All,2numbers
,201are in
,20percent.
K,20 The
K,2value
,201
K ,2central
Kof
012
,201assl is,20calculated
uncertainties.
according
1
1
1
0
0
2,U
1
1
2
1
2
1
1
1
,
,
,
,Up
,Up to11,Do
,Do
Dow
Up
Dow
2,U
1,U
2
1
,
,
p
D
D
wn
wn
p
p
own
own
n added in quadrature
n
Eq. 3. The uncertainties are
and multiplied
by 2/(1
fbkg ) = 2.45
to obtain
the uncertainties on assl .
Figure 4: Measured values of assl for the twelve individual data sets, with all corrections applied and
(%)
Stat.
uncert.
Syst. uncert.
corrected for the backgroundSource
dilution.Value
The blue
error
bars represent
the statistical
uncertainties.
Araw
0.11 and systematic
0.09
0.02
The red error bars represent the
statistical
uncertainties,
added in quadrature.
+
)
0.01
0.03( ⇡, K ⇤ K, and NR) mainly
track (K K
The uncertainties areApartially
correlated
between0.00
the three regions
(⇡ detection
µ+ )
0.01
0.05 The dashed
0.04
track
due to the corrections A
for
the
asymmetries.
line and the green horizontal
APIDof as 0.01
0.02
0.03
band represent the average value
and
its
uncertainty.
sl
Atrig (hardware)
0.03
0.02
0.02
Atrig (software)
0.00
0.01
0.02
fbkg Abkg
0.05
0.03
fbkg
0.06
Table 2: Background contributions
(f
),
efficiency
ratios
("
sig /"bkg ) and their e↵ective asymbkg
s
Total a
0.45
0.26
0.20
metries. The branching fractions slare obtained from the PDG [16]. The signal branching ratio
is B = (7.9 ± 2.4)%. The b-hadron fractions used are fu /fs = fd /fs = (3.86 ± 0.22) [28] and
- CPV in mixing
at LHCb
- BEAUTYaverage
2016
164
value
of A [29].(⇡ J.A.
µ+de
) Vries
is obtained
as the
weighted
of the two methods.
f 0 The
/f =final
(2.34
± 0.31)
17
LHCb-PAPER-2016-013
RESULTS
= (0.45 ± 0.26(stat) ± 0.20(syst))%
1
Standard Model
0
µµ
−4
−3
0
−3
D
−2
preliminary
−1
D0 Dsµ ν X
LHCb Dsµ ν X
asls [%]
s
asl
New
(prel result!
imina
r y)
LHCb D(*)µ ν X
D0 D(*)µ ν X
BaBar D*lν
BaBar ll
Belle ll
−2
−1
0
1
asld [%]
d and as . The horizontal and vertical
Figure 3: Overview of the most precise
measurements
of
a
sl 2016 sl
J.A. de Vries - CPV in mixing at LHCb - BEAUTY
18
LHCb-PAPER-2016-013
CLOSING STATEMENTS
New
• Measured
with full Run1 dataset (3/fb)
(p
resul
t!
relim
s
inar y
asl = (0.45 ± 0.26(stat) ± 0.20(syst))%
)
s
asl
•
Most precise value of CPV in mixing in the Bs system
•
Result compatible with Standard Model prediction
•
Statistics limited!
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
19
BACKUP
00
3000
3100
3200
M (µ +µ −)
V/c2]
[MeV/c2]
a
e "(f, f ) is the efficiency to detect a f or d
f final state. Hence, the observed, un
J/ ! µ+ µ candidates, (left) where the positive muon
metry
can be written as
sl
the negative muon is accepted or rejected by the trigger
the fits are overlaid, where the dashed lines show the
✓
◆
d
d
elds obtained from these fits
are
used
to
determine
the
N (f, t) N (f , t)
asl
asl
Ameas (t) =
⇡ AD +
+ AP
cos( md t) ,
2
2
N (f, t) + N (f , t)
Supplementary material for LHCb-PAPER-2014-053
e to a good approximation all higher-order asymmetry terms and the lifetime
0
appendix contains
supplementary
material that1 will
posted
on the publicasymmetry
cds record
in the BThis
system,
,
have
been
neglected.
The
production
c
d
but will
not appear in
the paper.
Muon
detection
asymmetry
Time correction
(k-factor)
mined simultaneously in a time-dependent analysis,
but the detection
asymmet
×10
obtained
independently.
The
production
and
detection
asymmetries are expec
14
1
1.5
Magnet up
d
LHCb
2012
LHCb
simulation
LHCb simulation
0.95
nd
on
the
kinematics
of
the
final
state,
but
a
to be universal. We a
12is expected
n
Magnet down
sl
1
− +
0.9
D
µ
Average
10
ligible level of direct CP violation in Cabibbo-favoured
tree decays of charm h
0.85
0.5
8
pected in the
SM.
It
is
noted
that
the
experimental
limits on these asymmetr
0.8
6
0
at the percent
0.75 level. See e.g. Ref. [13].
-0.5
Entries / ( 0.02 )
AD(µ ±) [%]
⟨k ⟩
3
0.7
4
0.65
2
-1
0.6
Experimental
00
0
50 approach
100
3000
3500
4000
4500
5000
0
0.4
p (µ ±)M[GeV/
(D−µ +c)] [MeV/ c2]
V/c]
es / ( 0.02 )
⟨k ⟩
0.9
0.8
1
1.2
1.4
k / ⟨k ⟩
0
decay
time
of
the
B
meson is calculated as
he muon trigger and
1 PID selection in bins of muon
, for (left) 2011 data
(right)
2012 data.
0.95 and
LHCb
simulation
0.6
×103
LHCb, PRL 114 (2015) 041601
10
LHCb simulation
M (B )L8 D* −µ +
J.A. de Vries -tCPV
=in mixing at LHCb - BEAUTY 2016
0
21
00
3000
3100
3200
M (µ +µ −)
V/c2]
[MeV/c2]
a
A(t )
e "(f, f ) is the efficiency to detect a f or d
f final state. Hence, the observed, un
J/ ! µ+ µ candidates, (left) where the positive muon
metry
can be written as
sl
the negative muon is accepted or rejected by the trigger
the fits are overlaid, where the dashed lines show the
✓
◆
d
d
elds obtained from these fits
are
used
to
determine
the
N (f, t) N (f , t)
asl
asl
Ameas (t) =
⇡ AD +
+ AP
cos( md t) ,
2
2
N (f, t) + N (f , t)
[arXiv:1604.03475]
Supplementary
for LHCb-PAPER-2014-053
LHCbmaterial0.5
0.5
e to a good approximation all higher-order asymmetry terms and the lifetime
0
appendix contains
supplementary
material that1 will
posted
on the publicasymmetry
cds record
in the BThis
system,
,
have
been
neglected.
The
production
c
d
but will
not
appear in
the paper.
Muon
detection
asymmetry
Time correction
(k-factor)
0
0 analysis,
mined simultaneously in a time-dependent
but the detection
asymmet
×10
obtained
independently.
The
production
and
detection
asymmetries are expec
14
1
1.5
Magnet up
d
-0.5
(a)
-0.5
(b)
LHCb
2012
LHCb
simulation
LHCb simulation
0.95
nd
on
the
kinematics
of
the
final
state,
but
a
to be universal. We a
12is expected
n
Magnet down
sl
1
− +
0.9
D
Average
5violation
10 in Cabibbo-favoured
10tree decays of charm h
10 5 µ
ligible level of direct
CP
0.5
0.85 0.5
0.5
8
pected in the
SM.
It
is
noted
that
the
experimental
limits on these asymmetr
0.8
6
0
at the percent
0.75 level. See e.g. Ref. [13].
0
0
-0.5
Entries / ( 0.02 )
AD(µ ±) [%]
⟨k ⟩
3
0.7
4
0.65
2
-1
(c)
-0.5
0.6 -0.5
Experimental
approach
00
0
50
100
3000
3500
4000
4500
5000
V/c]
5
(d)
p (µ ±)M[GeV/
(D−µ +c)] [MeV/ c2]
0
0.4
10
5
0.9
es / ( 0.02 )
⟨k ⟩
0
decay
time
of
the
B
meson is calculated as
he muon trigger and
1 PID selection in bins of muon
, for (left) 2011 data
(right)
2012 data.
0.95 and
LHCb
simulation
0.6
×103
10
0.8
1
1.2
1.4
k / ⟨k ⟩
10
t [ps]
LHCb simulation
M (B )L8 D* −µ +
J.A. de Vries -tCPV
=in mixing at LHCb - BEAUTY 2016
0
22
a
e "(f, f ) is the efficiency to detect a f or d
f final state. Hence, the observed, un
metry can be written as
sl
✓
◆
d
d
N (f, t) N (f , t)
asl
asl
Ameas (t) =
⇡ AD +
+ AP
cos( md t) ,
2
2
N (f, t) + N (f , t)
e to a good approximation all higher-order asymmetry terms and the lifetime
in the B 0 system,(*)- d , have been neglected.1 The production asymmetry c
D
mass
time
dependence
mined simultaneously in a time-dependent analysis, but the detection asymmet
×10
obtained×10independently.
The
production
and
detection asymmetries
are expec
Data
LHCb
Data
LHCb
300
Total
d
D −µ +
Total
+
− be
Signal
nd on the kinematics of the final
state,
but
a
is
expected
to
universal.
We
a
1000
D
µ
sl
Signal
B bkg.
200
B bkg.
Comb. bkg.
ligible level of direct CP violation
in Cabibbo-favoured
tree
decays
ofbkg.charm h
Comb.
500
100
pected in×10the SM. It is noted that the experimental limits on these asymmetr
60
at the percent
level. See e.g. Ref. [13].
3
*− +
3
Events / ps
Events / (2.8 MeV/c2)
3
+
+
40
D µ
20
Experimental
approach
0
1850
0
1900
−
0
Asymmetry [%]
3
M (D , Dis
) calculated as
decay time of the B meson
[MeV/c2]
2
1
0
-1
-2
1
10
t [ps]
3
t=
ents / ps
1: Mass distributions after weighting of (top) D candidates in the D µ+ sample and of ×10
m) D⇤ candidates in the D⇤ µ+ sample, with fit results overlaid.
0 200
M (B )L
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
LHCb, PRL 114 (2015) 041601
Data
Total
D* − µ +
23
Signal
LHCb
Table 2: Background contributions (fbkg ), efficiency ratios ("sig /"bkg ) and their
e↵ective asymLHCb-PAPER-2016-013
metries. The branching fractions are obtained from the PDG [18]. The signal branching ratio
is B = (7.9 ± 2.4)%. The b-hadron fractions used are fu /fs = fd /fs = (3.86 ± 0.22) [31] and
f⇤0 /fs = (2.34 ± 0.31) [32].
ASLS PEAKING BKG DETAILS
b
Mode
(⇤)+
B + ! D(⇤)0 Ds X
(⇤)+
B 0 ! D 0 Ds X
(⇤)+
B 0 ! D Ds X
(⇤)
(⇤)+
Bs0 ! Ds Ds
(⇤)+
⇤0b ! ⇤+
D
X
s
c
B ! Ds+ K µ ⌫X
B 0 ! Ds+ KS0 µ ⌫X
B [%]
7.9 ± 1.4
5.7 ± 1.2
4.6 ± 1.2
4.5 ± 1.4
10.3+2.1
1.8
0.061 ± 0.010
0.061 ± 0.010
B(c ! µ) [%]
6.5 ± 0.1
6.5 ± 0.1
16.1 ± 0.3
8.1 ± 0.4
4.5 ± 1.7
–
–
"sig /"bkg
4.34
4.08
6.41
3.68
4.51
2.43
2.89
fbkg /fsig [%]
5.8 ± 1.1
4.4 ± 1.0
5.6 ± 1.5
1.0 ± 0.3
3.0 ± 1.4
1.3 ± 0.2
1.1 ± 0.2
Abkg [%]
0.6 ± 0.6
0.18 ± 0.13
0.18 ± 0.13
0.4 ± 0.9
0.6 ± 0.6
0.18 ± 0.13
10
J.A. de Vries - CPV in mixing at LHCb - BEAUTY 2016
24