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The LHCb experiment. Walter Bonivento – I.N.F.N. Sezione di Cagliari - Italy. Why B physics at the LHC. At LHC start-up several precise measurements will be available from B-Factories and Tevatron to test the CKM paradigm of flavour structure and CP violation. - PowerPoint PPT Presentation
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Walter Bonivento - INFN Cagliari
The LHCb experiment 1
The LHCb experiment
Walter Bonivento – I.N.F.N. Sezione di Cagliari - Italy
Walter Bonivento - INFN Cagliari
The LHCb experiment 2
Why B physics at the LHC
If NP will be found at LHC in direct searches, B Physics measurements will allow to understand its nature and flavour structure.
At LHC start-up several precise measurements will be available from B-Factories and Tevatron to test the CKM paradigm of flavour structure and CP violation.
However New Physics could still be hidden in mixing, in box and in penguin diagrams, realm of indirect discoveries.
Walter Bonivento - INFN Cagliari
The LHCb experiment 3
Unitarity triangles• At the level of precision that will be probed by LHCb, there are two
unitarity relations of the CKM matrix that are of interest:
• Possible situation of the measurements when LHCb starts to take data:
measurement of the angle will be crucial
Differ at the percent level
phase of Vts
~240
SM)~650
χ(SM)~10
Walter Bonivento - INFN Cagliari
The LHCb experiment 4
χ
~Vub* ~Vtd
~Vts
00Sd KΨJB
)('0 , ΨJΦΨJBs , ρππBd
0
KDBπDB
ss
d
0
02χ
DDBKDBKDB
sc
d
d
0
000
0
KKBB sd00 and and
~Vub* ~Vtd
~Vcb
Which B decays to measure the angles?
Walter Bonivento - INFN Cagliari
The LHCb experiment 5
Precise determinations including from processes only at tree-level, in order to disentangle possible NP contributions
Several other measurements of CP phases in different channels for over-constraining the Unitarity Triangles
BsDsK, B0D0K*0, B0BsKK,…
B0K* B0K*0l+l-, bsl+l-, Bs...
B0Ks, BsB0B0…
A complete program on B Physics includes:
BsDs, … BsJBsJ(’)
Precise measurement of B0s-B0
s mixing: ms, s and phase s.
Search for effects of NP appearing in rare exclusive and inclusive B decays
Walter Bonivento - INFN Cagliari
The LHCb experiment 6
PYTHIA
Why a forward detector for B physics at LHC
K-
B0
s K+
p p
few mm
1) b and bbar are mostly produced at small angles wrt beam pipe AND correlated in one unit of rapidity forward spectrometer to measure b decays and TAG them
2) large Lorenz boost large B meson average momentum ~ 80 GeV large average mean flight path ~cm accurate measurement of proper time is possible (few % ) AND selection of B decays at TRIGGER level is possible
3) momentum distribution match particle ID capabilities of RICH detectors ROOM is available for the detectors, contrary to cylindrical geometry
4) relatively low pT muon triggering possible because iron penetration depends here on pL which is large
Walter Bonivento - INFN Cagliari
The LHCb experiment 7
Detector requirements(I)Physics requirements(I)•Main constraint: the DELPHI cavern (20m)•Collision point in one side•Fixed target experiment design with dipole field magnet good analysing power for forward tracks•Acceptance: 250(300) mrad-10mrad
Efficient particle identification :- p/K separation (1-->100 GeV) --> RICH ; also for flavor tagging, …)- electron and muon ID --> CALO + MUON (for B0(s) --> J/ψ X, flavour tagging, …)
defines the momentum range for the spectrometerand for particle ID
Walter Bonivento - INFN Cagliari
The LHCb experiment 8
to measure the fast Bs oscillations,where A(mix)α cos(ΔmS τ), if ΔmS=20ps-1, oscillation period is T=300fs need a proper time resolution at least of σ(τ) ~< T/2π σ(τ)/<τ>(1.5ps)~ few %
But L= γβcτ = p/m cτ σ(p)/<p> <few % and σ(L)/<L> <few %
But average decay length ~7mm need a vertex detector to measure it at the few % level (~200μm)exercise: try to reconstruct the argument arguing the path length in the lab frame in one oscillation period
Background rejection mass (p and angular) resolution
Rare decays with many tracks (up to 5) efficient tracking with low X0 (m.s. and γ conversions)
- tracker and magnet
Physics requirements(II)
magnet
Walter Bonivento - INFN Cagliari
The LHCb experiment 9side view
Single arm forward spectrometer
pp collision
Acceptance
10 mrad
250/300 mrad v / h
The experiment
Walter Bonivento - INFN Cagliari
The LHCb experiment 10
to avoid high number of interaction / bunch crossings :
L = 2 .1032 cm-2s-1 for LHCb
--> simpler events (one interaction per bunch crossing dominates) and less radiation damage
for the detectors
• σinelastic 80 mb and σ bb 0.5 mb
--> need an efficient trigger (also on fully hadronic channels)
trigger strategy:
a) first level, hardware: large B mass large pT of B decay products; and selection of single interaction events
b) second level, software: large B lifetime large impact parameters
Key issues
Walter Bonivento - INFN Cagliari
The LHCb experiment 11
Comparison to other experiments• Enormous production rate at LHCb: ~ 1012
bb pairs per year much higher statistics than the current B factoriesBut more background from non-b events challenging triggerand high energy more primary tracks, tagging more difficult
• But in addition, all b-hadron species are produced: B0, B+, Bs, Bc , b …
• Only competition before LHC is from CDF+D0 (lower statistics, poorer PID)
• ATLAS and CMS will only have lepton trigger, poor hadron identification
230b100b
σ(B)
2003 2007
BdJ/KS
Bd
BsJ/ Bs DsK
LHCb 1y
Walter Bonivento - INFN Cagliari
The LHCb experiment 12
VELO
Vertex locator around the interaction region
Reconstruction of decay vertexes of b and c hadrons and IP for flavor tagging + fast response for L1
Walter Bonivento - INFN Cagliari
The LHCb experiment 13
VELO (II)
Design requirements and criteria:a) Impact parameter resolution b) L1 trigger fast stand alone patter recognition
MAIN IDEA: for B hadrons (IP)rz large but (IP)xy small the L1trigger first reconstructs in rzand then in 3d ONLY the tracks with large IP strips with constant r and (in other sensors) radial strips with stereo angle of 10-200
multiple scattering in RF foils and detectors
Δ01
Δ02
r1 r2
track
IP
intrinsic resolution of the sensors
to have an equal contribtution from the 2 measured R points: σ2= σ1· r2/r1 strip pitch increasing linearly with radius
small!!!
small extrapolation factor
Walter Bonivento - INFN Cagliari
The LHCb experiment 14
~1m
Interaction region Downstre
am
21 stationsRetractable detector halves
VELO(III)
• 21 silicon tracking stations placed along the beam direction
• 2 retractable detector halves for beam injection periods
(up to 30 mm)
• an average track crosses 7 stations
while <0.1% crosses <4 stations
+ some geometrical constraints:primary vertex σ(z)~5.6cm ± 2 σeta coverage required: ( 15-250mrad) - maximum wafer sizes 100mm - minimum safe radius 8mm
Walter Bonivento - INFN Cagliari
The LHCb experiment 15
VELO(IV)
x=5% of X0
σ=8μm
up to 3GeV/c it is multiple scattering dominated!lop p tracks limit the L1 performance!!
from simulation
30 μm
Walter Bonivento - INFN Cagliari
The LHCb experiment 16
VELO Sensor design
• 2 sensor types: R and – R measuring gives radial position – measuring gives an approximate azimuthal
angle
• Varying strip pitch– 40 to 102 m (R – sensor)– 36 to 97 m ( – sensor)
• First active silicon strip is 8.2 mm from the beam line
• n+-on-n DOFZ silicon– minimises resolution and signal loss after type
inversion – the high field side is always on the strip side in
order to prevent loss of resolution and signal
• Double metal layer for detector readout
R-measuring sensor:
(concentric strips)
–measuring sensor:
(Radial strips with a stereo angle)
Walter Bonivento - INFN Cagliari
The LHCb experiment 17
Double sided modules
(1 x R and 1 x sensor)
Cooling contacts
Carbon fibre paddle
TPG* substrate with carbon fibre frame
16 Beetle chips
Silicon Sensor
Secondary vacuum ChamberRetracting Detector Half
Silicon operating temperature -7oC
*Thermalised Pyrolytic Graphite
VELO in the Vacuum
Walter Bonivento - INFN Cagliari
The LHCb experiment 18
VELO environment
• VELO sensors operate in a harsh non-uniform radiation environment
– fluence to inner regions 1.3 x 1014 neq./cm2
– fluence to outer regions 5 x 1012 neq./cm2
• Estimated to survive 3 years
Illustration of Vdep …
R/cm
Vdep
Walter Bonivento - INFN Cagliari
The LHCb experiment 19
Tracking system
Tracking system and dipole magnet to measure angles and momenta
Walter Bonivento - INFN Cagliari
The LHCb experiment 20
A particle of (pX, pY ,pZ) transversing (0,BY,0) receives a momentum kick of ΔpX=-e∫ BY dz and p= ΔpX/(sin α IN - sin α OUT)QUESTION: how to get pT?
Then σP/p = 2* (σX/L) ·p/ (e∫ BY dz ) with L the lever arm(Kleiknecht, Phys Rep,84, pp 85-161(1982)) .( σP/p )MS ~√x/X0, independent of pminimise material!!
To achieve σP/p ~0.5% at 100GeV/c, assuming some σX =100μ of detector point resolution, L~2.5ma bending power of ~4Tm is needed
warm magnet: 2 Al coils + iron yokeexcitation current : 2x2MApower dissipation: 4.2MWL(coil)=2H !!!
but easy ramp up and possibility to revert the field to check systematics on B asymmetries…
The spectrometer and the magnet
z
x
BY
z
y
BY
α IN
Walter Bonivento - INFN Cagliari
The LHCb experiment 21
TTIT
OT
T1T2T3
The tracking chambers
4 layers/station (2 stereo)
4 layers/station (2 stereo)
1.3% of the area but20% of the particles!!!!occupancy<0.5%
type inversion NOT of concern here!!
occupancy<7%
Cdet~50pF
straw (=cannuccia) tubes; 5mm cell diameterAr/CO2; light matrix nomex; light wrapping (Al)
Walter Bonivento - INFN Cagliari
The LHCb experiment 22
Track reconstruction (I)
In BJKs 25% of Ks decay in the VELO acceptance 50% before the TT
25% downstream of TT
reconstructed tracks72 on average in bb event: 26 long 11 upstream 4 downstream 26 VELO 5 T
VELO
TT
TT
T1-T3
Walter Bonivento - INFN Cagliari
The LHCb experiment 23
Track reconstruction(II)
Example of reconstruction strategy: for Long tracks
A) FORWARD TRACKING (90% of long tracks)
1) start from a VELO seed (straight lines, low B field, NO p information)
2) combined with T-seed (parabola, B information)
3) search for TT hits
B) BACKWARD TRACKING
4) from remaining T hits extrapolate back to VELO
5) all tracks refitted with Kalman filter (dowstream to upstream)
Walter Bonivento - INFN Cagliari
The LHCb experiment 24
Track reconstruction(III)Long tracks
13.3 VELO, 17(22) IT(OT), 4 TT 98.7% of hits correctly assigned!!
Walter Bonivento - INFN Cagliari
The LHCb experiment 25
Track reconstruction(IV)Long tracks
Ks reconstruction in BJKs
DD
LL
LU
σ=4MeV
ε=55-75%multiple scattering dominated up to 100GeV
σ
Walter Bonivento - INFN Cagliari
The LHCb experiment 26
RICH
Two RICH detectors for charged hadron identification
Walter Bonivento - INFN Cagliari
The LHCb experiment 27
RICH (II)photon detectors
radiator gas (n)
beam pipe
mirrors
Walter Bonivento - INFN Cagliari
The LHCb experiment 28
RICH (III)
charged particle
C
if v>c/n
or β>1/n
Walter Bonivento - INFN Cagliari
The LHCb experiment 29
RICH (IV)
charged particle
C
2
111
cosp
m
nnC
particle mass!
Walter Bonivento - INFN Cagliari
The LHCb experiment 30
2 RICH, 3 Radiators
RICH1upstream of the magnet
• Aerogel (2 - ~10 GeV/c); n=1.03
• C4F10 (10 -~60 GeV/c); n=1.0014
RICH2 downstream of the magnet
• CF4 (16 – 100 GeV/c); n=1.0005
2
2
)(
11sin)(
nN C
for low n needs a longer path for the charged particle
2m1m
Walter Bonivento - INFN Cagliari
The LHCb experiment 31
Typical event
Question: what are the Aerogel rings?
Walter Bonivento - INFN Cagliari
The LHCb experiment 32
Particle ID
3 radiators provide excellent pion/kaon separation !
2
11
cosp
m
nC
Walter Bonivento - INFN Cagliari
The LHCb experiment 33
Particle ID
In BDsK
Momentum (GeV/c)
/ K
se
par
atio
n
Provide > 3–K separation for 3 < p < 80 GeV
Walter Bonivento - INFN Cagliari
The LHCb experiment 34
Particle ID
In BDsK
and for kaon/proton…
it is possible to tune the PID cut (efficiency/purity) depending on the specific physics analysis
Walter Bonivento - INFN Cagliari
The LHCb experiment 35
Calorimeter system
Calorimeter system to identify electrons, hadrons and neutrals
Important for the first level of the trigger
e
h
Walter Bonivento - INFN Cagliari
The LHCb experiment 36
Muon system
Muon system to identify muons, also used in first level of trigger
Walter Bonivento - INFN Cagliari
The LHCb experiment 37
Trigger (I)
The 3 levels of the LHCb Trigger – Level-0 hardware trigger (10 MHz 1MHz ; 4μs latency)
• Fully synchronous and pipe-lined (deadtime < 0.5%)• Pile-up System• Calorimeter and Muon high pT e, , 0,, or hadrons• Flexible L0 Decision unit
– Level-1 software trigger (1MHz 40kHz ; max latency 1ms)• Partial read-out: Vertex Detector (VeLo), Trigger Tracker (TT) and L0
summary p info thanks to magnet fringe field!!!– High Level software trigger (HLT)(40kHz200Hzstorage; 10ms)
• Full read-out: all detector data
Com
mon
h
ard
ware
In 10 Mhz of crossings with visibile pp interaction 100kHz of bb pairs; only 15% will have one Bwith all decay products in the accepatance; and BR for CP violation are at 10 -3 level!!!
At LHC energies bbar events very similar to minimum bias except for 2 things:1) high pT of decay products2) detached secondary (and tertiary) vertexes
The challenge:
Walter Bonivento - INFN Cagliari
The LHCb experiment 38
~ O(1) kHz
How to determine the rejection level demanded by the L0?
1) Luminosity 2) L0 output rate
defines the minimum bias retention i.e. the rejection level
Trigger (II)
Walter Bonivento - INFN Cagliari
The LHCb experiment 39
Muon system and trigger(I)
track finding (straight line to IP)and pT calculationquestion to students: how is pt calculated from muon system alone?
Triggering: OR of 5 stations minimum p of 5Gev (not pT!!!); rates varying from 100Hz/cm2 to 500kHz/cm2 higher than ATLAS or CMSMuon id. tagging and final state reconstruction
logical layout
high rate, high efficiency and ageing MWPCand Triple-GEM for M1R1 Ar/CO2/CF4 gas mixtures
with F.O.I. (few pads in the bending plane..)
each station has a pad segmentation
Walter Bonivento - INFN Cagliari
The LHCb experiment 40
Muon system and trigger (II)
offline muon i.d.
standalone pT reconstruction ~ 20%
trigger performance
Main background: π and μ decays need to reduce by 50-100
less efficient at low p due to multiple scattering and decays in flight
Walter Bonivento - INFN Cagliari
The LHCb experiment 41
Calorimeter system and trigger(I)
projective geometry: ECAL, SPD, PSD 4x4, 6x6 and 12x12 cm2
HCAL 13x13, 26x26 cm2
Preshower e from π± (introduces a longitudinal segmentation in the calo)SPD e from π0
In the muon trigger the signal dominates the only parameter to control the trigger rate is pT
For electron, completely different environment from the muons : background dominates!!!
irreduciblebackground
(suppressed at L1)
12% of λI
Walter Bonivento - INFN Cagliari
The LHCb experiment 42
Calorimeter system and trigger(II)
Hadronic: iron-scintillating tiles with WLS fibers e.g. ATLAS
E 10% , 5.6λI
80%
performance of the hadron trigger(essentially a pt cut)less efficient of e and μ
cluster 2x2 cells
offline electron i.d.
E 1% ,
10%Electro-magnetic: Shashlik type
P.M.
25X0
e.g. DELPHI LumiMON
WLS fibers
performance of the electron trigger
BJ KR
pT
Bπ πR
pT
ε
ε
Walter Bonivento - INFN Cagliari
The LHCb experiment 43
PILE-UP VETO IP (95% of lumi)
vs cut vs luminosity
Why is it useful?
Walter Bonivento - INFN Cagliari
The LHCb experiment 44
HCAL trigger domina
tes
MUON trigger domina
tes
ECAL trigger domina
tes
L0 performance
OR
from the other B! typically in one unit of rapidity
less rejection
Walter Bonivento - INFN Cagliari
The LHCb experiment 45
L1 ingredients
Makes use of the 1) VELO 2D tracks IP
2) VELO+TT pT
3) L0 information
Walter Bonivento - INFN Cagliari
The LHCb experiment 46
Level-1 Decision Algorithm
Bandwidth division:
Overlaps are absorbed in this direction
Generic
Single-muon
Dimuon, general
Dimuon, J/PsiElectron
Photon
1) generic algorithm (IP+pT of PT1 and PT2) + specific (level 0 signatures+ 3D track reconstruction )
Walter Bonivento - INFN Cagliari
The LHCb experiment 47
L0 efficiencyL1 efficiency
L0*L1 eff.
Combined efficiency of L0 and L1
Walter Bonivento - INFN Cagliari
The LHCb experiment 48
Trigger Rates Overview
Level-0 Level-1HLT
L1-confirmationHLT
Full reconstruction
5.6%
1%
Walter Bonivento - INFN Cagliari
The LHCb experiment 49
The Physics
We concentrate here on few benchmark measurements driving the experiment design
•B0s D-
sπ+ ΔmS
•B0d J/ S β
•B0s J/ χ and ΔΓS
•B0s Ds
K-+ γ
Walter Bonivento - INFN Cagliari
The LHCb experiment 50
Time-dependent decay ratesB(BS) decay to a final state f:
q/p=exp(-iφ)=exp(2iχ)(phase of Bs-Bsbar mixing)
Walter Bonivento - INFN Cagliari
The LHCb experiment 51
CP violating asymmetriesff and and
ff Any difference between or CP violation
Walter Bonivento - INFN Cagliari
The LHCb experiment 52
The method for measuring the time dependent asymmetry: a case study
BSDSK(π)
1) reconstruct the signal B2) tag the flavor of the other b at production (always b and bbar produced)3) measure asymmetry vs time reconstruct the proper time
Walter Bonivento - INFN Cagliari
The LHCb experiment 53
Event selection(I)
τ(Bs)=1.5psτ(Ds)=0.5ps
few cm
bachelor = s.m. celibe, scapolo
+<pB>~80GeV
Walter Bonivento - INFN Cagliari
The LHCb experiment 54
Event selection(II)
Two types of background:
1) from other B decays similar to the one considered
2) combinatorial: the dominant contribution assumed from forward bb events107 generated(only few minutes of LHCb data taking)estimates statistically limited upper limits derived on S/B
sometimes some cuts relaxed (e.g. invariant massof B) to increase statistics it will be determined from the data using sidebands of mass distributions
Walter Bonivento - INFN Cagliari
The LHCb experiment 55
Event selection(III)
track selection 1) some minimum pt (~ 300 MeV/track)+
primary vertex reconstruction quite good due to ~60 tracks even if it is boosted
ε=98%
2) some PID on tracks(this plot concerns the bachelor)
Walter Bonivento - INFN Cagliari
The LHCb experiment 56
Event selection(IV)Ds vertex selection
+unconstrained vertex fit constrained vertex fit
+cuts on IP and D to PV
Walter Bonivento - INFN Cagliari
The LHCb experiment 57
Event selection(V)Bs vertex selection
+unconstrained vertex fit constrained vertex fit
signed distance between B and D
better than for D due tolarge opening of bachelor and Ds (large B mass)
collinearity of p(B) and distance primary-secondary vertex
Walter Bonivento - INFN Cagliari
The LHCb experiment 58
Event selection(VI)
Bs invariant mass
σ(M)~14MeV
B0
error dominated by p measurementin the spectrometer
the VELO provides the angle
after identification with RICH!!!!
Walter Bonivento - INFN Cagliari
The LHCb experiment 59
Annual yields and backgrounds
geometrical and secondary interactions
track finding
Walter Bonivento - INFN Cagliari
The LHCb experiment 60
Flavor tagging(I)Full reconstruction or even partial very difficult: small reconstructible BR, geometric acceptance,reconstruction efficiencyrely on charge correlations of decay leptons (bl) or kaons (bcs) large tagging efficiencybut sometimes erroneus tags
leptonspTkaonsIP
wrong tags: leptons from π and K decays, bcl, BDS+X give two kaons and flavor oscillationsfor neutral B’s
Walter Bonivento - INFN Cagliari
The LHCb experiment 61
Flavor tagging(II)
Wrong tag fractions will be determined from the data: from control channels which are flavor-specificsuch as JK*0
to be compared to CDF/D0~1% and B-factories ~30%
wrong tag fraction
Walter Bonivento - INFN Cagliari
The LHCb experiment 62
Proper time
proper time τ resolution~ 30-40 fs
dominated by the error on the decay length(the error on p accounts only for 8fs)
very important due to fast oscillations of Bsbrings anyway a 30% of dilution of the asymmetry!!
L= γβcτ = p/m cτ
(ATLAS and CMS ~50-70fs)
Walter Bonivento - INFN Cagliari
The LHCb experiment 63
Mixing measurement : B0s D-
sπ+
Final state: flavour-specific (can be reached by the B and not by the Bbar), non CP eigenstate only one single tree diagram contributes (B0
s D-sπ+ does not exist)
it does not lead to CP violating observables but…
dilution factor: wrong tag fraction and experimental resolutionNot CP viol
sb
W
sc
du
0sB
sD
large branching fraction + large expected asymmetry whose amplitude we can calculate
those who have oscillated
Walter Bonivento - INFN Cagliari
The LHCb experiment 64
Error on the amplitude vs ms
can make a 5 measurement in one year for ms up to 68 ps-1 (far beyond Standard Model expectation of 20 ps-1)
Once a Bs–Bs oscillation signal is seen, the frequency is precisely determined: ms ) ~ 0.01 ps-1
tme S
t
Dscos
2cosh~
Walter Bonivento - INFN Cagliari
The LHCb experiment 65
CP asymmetry: B0d J/ S
In the S.M. Adir=0 (i.e. |λ|=1) and Amix=Im(λ)=sin(2β)
σ=12 MeV/c2 9MeV/c2
Ks downstream Ks long
Ksd d
md = 0.502 0.006 ps-1
Final state: flavor non specific, CP eigenstate
() ~ 0.60, () ~ 0.023 in one year
Walter Bonivento - INFN Cagliari
The LHCb experiment 66
CP asymmetry: B0s J/
• Bs counterpart
of B0 J/ψ KS
• In Standard Model expected asymmetry sin 2very small ~ 0.04 sensitive probe for new physics
• Reconstruct J/ or ee, KK
• Final state is admixture of CP-even and odd contributions angular analysis of decay products required
() ~ 1.70, (s/s) ~ 0.02 in one year
σ(M)~15MeV
Walter Bonivento - INFN Cagliari
The LHCb experiment 67
1. Bs->DsK (14-150)
2. B->, Bs->KK
(4-60)
3. B->DK*(7-80)
not affected by new physics in loop
diagrams
affected by possible new physics in
penguin
Determine the CKM parameters A, ,
independent of new physics
Extract the contribution of new physics to the
oscillations and penguins
affected by possible new physics in
D-D mixing
Measurements of γ
1 year sensitivity
Walter Bonivento - INFN Cagliari
The LHCb experiment 68
CP asymmetry: Bs Ds K-+
large interference effects
2 asymmmetries 6 observables…
Final state: flavor non specific non CP eigenstate
Walter Bonivento - INFN Cagliari
The LHCb experiment 69
CP asymmetry: Bs Ds K-+
• Very little theoretical uncertaintyInsensitive to new physics, which is expected to appear in loops
• Reconstruct using Ds KK
…which are functions of the parameters:(allow for possible strong phase difference δ between the two diagrams)
r=|λ|
-2χ
-2χ
-2χ-2χ
Walter Bonivento - INFN Cagliari
The LHCb experiment 70
• Fit two time-dependent asymmetries: Ds
+Kasymmetry δ ( Ds
Kasymmetry δ (can extract bothδand(
will be determined using Bs J/ decays extract
Asymmetries for 5 years of simulated data
() ~ 14 in one year
ms=20 ps-1
data generated with
Walter Bonivento - INFN Cagliari
The LHCb experiment 71
THE END