Download - Heavy flavours and QCD Selected LHCb results
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SB 1LHCb results: heavy flavours and QCD Trento, 15.09.11
Heavy flavours and QCD
Selected LHCb results
Sergey Barsuk, LAL Orsay
on behalf of the LHCb collaboration
: La nascita, la vita e la morte degli aromi pesanti a LHCb
Outline
Heavy flavour production
Onia production / Open charm and beauty production / Exotics Lifetime-based studies Heavy flavour hadron decays & CPV
Angle / BsBs mixing phase φs / New results on b-baryons /
/ Radiative penguines bs / Search for Bsμμ
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SB 2LHCb results: heavy flavours and QCD Trento, 15.09.11
Heavy flavours – excellent place to hunt for effects beyond
Standard
Model
Strategic attack on SM by LHCb : examples of where LHCb can
contribute
Hot channels for the near future:
Bs μ μ : Is there SUSY? BR ~ tan6β / m4A .
Bs J/ψφ et al. : Beyond-SM CPV?
Bd μ μ K* : Right-handed currents?
(φ3) : Is the CKM matrix sufficient?
yCP: Beyond-SM CPV in charm?
My goal is to show results / potential
of LHCb in these areas …
talks by Antonio Masiero and Marco Ciuchini
Introduction
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SB 3LHCb results: heavy flavours and QCD Trento, 15.09.11
Correlated bb production, second b in acceptance once the first b is in (flavour tagging) LHCb covers forward region: 1.9 < η < 4.9
optimized for forward peaked HQ production at the LHC only ~4% of solid angle, but ~40% of HQ production cross section
LHCb design overview
Bunch crossings at 40 MHz, can store < 3 kHz Aim at reducing rate, while storing as many HQ as possible, two-stage trigger:
Hardware-based L0 trigger employs moderate pT cuts, reduces rate to 800 kHz Then full event information can be used by the trigger farm (HLT)
Unique acceptance amongst LHC experiments: can explore QCD in the forward region LHCb covers forward region: 1.9 < η < 4.9
Busy events, O(200) particles/event
Large cc and bb production cross section at LHC : with ALL c- and b-species produced,
e.g. 50k bb events/s
JINST 3:S08005,2008
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SB 4LHCb results: heavy flavours and QCD Trento, 15.09.11
250 mrad
10 mrad
Vertex reconstruction:
VELO
Trigger:Muon Chambers
CalorimetersTracker
PID:RICHs
CalorimetersMuon Chambers
Kinematics:MagnetTracker
Calorimeters
Calorimeters
MuonSystemTracking
RICH countersp/K/π Identification
VErtexLOcator
p p
LHCb detector – single-arm forward spectrometer 10-250 mrad (V), 10-300 mrad (H)
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SB 5LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb lifetime measurements using 36 pb-1 of 2010 data
1.638 ± 0.0111.525 ± 0.0091.525 ± 0.0091.477 ± 0.0461.391 ± 0.038
PDG [ps]LHCb [ps]
Vertex Locator (VELO) provides excellent proper time resolution of ~50 fs
VErtex LOcator: precision tracking and vertexing LHCb-CONF-2011-001
VELO sensitive area gets 8 mm to the beam axis
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SB 6LHCb results: heavy flavours and QCD Trento, 15.09.11
Charged hadron identification: Cherenkov detectors
Muon detector
0
X
Particle identification
photon/electron/hadron PID: calorimeter
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SB 7LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb collected ~37 pb-1 in 2010 and already >700 pb-1 in 2011. Goal for 2011: 1 fb-1
LHC reached nominal peak luminosity of
2x1033 cm-2s-1 with number of bunches ~1300
from ~2600 LHCb recording >1pb-1/hour running at
L~3.3x1032 cm-2s-1 (higher, than nominal,
2x1032 cm-2s-1 ) in auto-leveling mode
LHCb tested operation up to 4x1032 cm-2s-1
Visual average number of vertices now is higher µ ~1.4, compared to nominal µ =0.4 Higher µ higher track multiplicity, 1 PV gives 30 tracks/rapidity range,
dangerous for reconstruction
dangerous background for D and B decay vertex reconstruction average minimum distance between 4 PVs ~12 mm, comparable to average B travel
distance ~10 mm
LHCb luminosity levelling
~30 pb-1 in 29 h in a single fill.
dL/dt ~ 100 pb-1/week possible !
LHCb operation
LHCb(design)
ATLASCMS
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SB 8LHCb results: heavy flavours and QCD Trento, 15.09.11
Heavy flavour production: LHCb as a flavour factory
Onia production: J/ψ, χc, ϒ(1S), χb
Exotics: X(3872), X(4140) b-hadron production: inclusive production, B, Bs, Bc Exclusive charmonium production
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SB 9LHCb results: heavy flavours and QCD Trento, 15.09.11
Onia production: J/ψ and ϒ(1S) LHCb-CONF-2011-016
Measurements getting more precise than theory, given polarisation will be measured.
Mechanism of onia production: colour single model, octet model, evaporation model...?
Eur.Phys.J. C71 (2011) 1645
J/ψ prompt J/ψ from b
P.Artoisenet, M.Butenschon, B.A.Kniehl
ϒ(1S)
P.Artoisenet, J.M.Campbell, J.P.Lansberg, F.Maltoni, F.Tramonato
Adequate description of J/ψ production, while still big uncertainty for ϒ(1S)
32 pb-1
32 pb-1
5.2 pb-1 5.2 pb-1
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SB 10LHCb results: heavy flavours and QCD Trento, 15.09.11
χc and χb production using radiative decays χcJ/ψ γ and χbϒ(1S)γLHCb-CONF-2011-020
Challenge to resolve χc1 vs. χc2
σ(χ
c2
)/σ
(χc1
)
NLONRQCD
LO colour singlet
First results for relative production of χc1 vs. χc2 are not well described by NLO
NRQCD.
χb0,1,2 can not be resolved
No sign of χb(2P) reported by CDF
(PRL 84 (2000) 2094), though ϒ(1S) statistics ~30 times larger.
350±59 events
35 pb-1
35 pb-1
37 pb-1
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SB 11LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb preliminary
376 pb-1
M(J/Ψππ)-M(J/Ψ)
B+X(3872)K+
Exotics: X(3872), observation, mass, x-section
Mass calibrated by scaling track momenta and constraining ϒ(1S),ψ(2S)μμ, DoKπ and
KoS ππ masses. Control channel: ψ(2S)J/ψ ππ.
With 2011 data perform: precise mass measurements angular studies [LHCb-PUB-2010-
003] in BX(3872)K to access JPC of
X(3872)
LHCb-CONF-2011-021
LHCb-CONF-2011-043 Exotic, internal structure uncertain, possibly a DoD*o molecule.
Precise mass crucialInclusive measurement, LHCb 2010 data, 35 pb-1
for 5 GeV/c < pT < 20 GeV/c, 2.5 < η < 4.5. 35 pb-1
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SB 12LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb preliminary
376 pb-1
B+J/ΨφK+ ~360 decays
(c.f. 115 for CDF
in 6 fb-1)
Background model is 3-body phase space convoluted with resolution
LHCb does not confirm presence of X(4140).2.4σ tension with CDF (using this background model)
CDF observed a 5σ structure, X(4140), X(4140)J/Ψ φ in B+J/ΨφK+ events [arXiv:1101.6058].
LHCb now has a large sample of these decays.
CDF ~6 fb-1
fit: 7±5
expected signal scaled from CDF: 39±9±6
Exotics: search for the X(4140) LHCb-CONF-2011-045
LHCb preliminary
376 pb-1
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SB 13LHCb results: heavy flavours and QCD Trento, 15.09.11
b-hadron production studies:
b-production with B+J/ΨK+
Measurements reasonably well described by theory (FONLL, MC@NLO)
b-hadron production
Detached J/Ψ: σ4πbb = (288 ± 4 ± 48) μb
Dμ tags: σ2 < η < 4bb = (75 ± 5 ± 13)
μbσ4πbb = (284 ± 20 ± 49) μb
Fully reconstructed J/Ψ X states:
LHCb-CONF-2011-033
Phys. Lett. B 698 (2011) 14
Eur. Phys. J. C 71 (2011) 1645
35 pb-1
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SB 14LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb measured fragmentation fractions: relative rates of B+, Bo, Bs, Λb ...
BsDs-π+ BoD-K+
Two complementary approaches:
1. Ratio of related hadronic decays, e.g. BoD-K+ and BsDs-π+
2. Semi-leptonic analysis with Do μX, D+ μX, Ds μX & Λc μX events and accounting for
cross-feeds [LHCb-CONF-2011-028]
[arXiv:1106.4436, sub. to PRL]
Consistent results for Bs/Bo fragmentation ratio, fs/fd, which thus can be combined:
<fs/ fd> LHCb =
0.267
Necessary input for e.g. BR(Bsμμ)
fs/fd not a priori a ‘universal’ number,
but similar to LEP and Tevatron result.
+0.021-0.020
LHCb-CONF-2011-034
b-hadron production
LHCb, 35 pb-1 LHCb, 35 pb-1
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SB 15LHCb results: heavy flavours and QCD Trento, 15.09.11
Relative Bc+ to B+ meson production
Production of Bc+ is added by measuring it relative to B+,
in the fiducial region pT > 4 GeV/c,
2.5 < η < 4.5. LHCb 2010 data: 32.5 pb-1
3476 ± 62 events
43 ± 13 events
Uncertainty is mainly statistical, systematics dominated by the Bc
+ lifetime
measurement.
LHCb-CONF-2011-017
32.5 pb-1 32.5 pb-1
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SB 16LHCb results: heavy flavours and QCD Trento, 15.09.11
Usually proton collisions produce very many final state particles because the gluon is a coloured object. But if a colourless object is exchanged…..
Exclusive quarkonia production
J/ψ and ψ’ exclusive production are interpreted as photon-pomeron fusion or odderon-pomeron fusion;
χc exclusive production is interpreted as double pomeron exchange;
exclusive di-muons come from photon-photon fusion.
Clean signature: No backward tracks (gap of 2 units of rapidity) Precisely two forward muons No photons (for J/ψ and diphoton process)
One photon (for c analysis)
LHCb-CONF-2011-022
Talk by Alain Martin
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SB 17LHCb results: heavy flavours and QCD Trento, 15.09.11
Use of backwards tracks, non-exclusive production
Backward Forward tracks
Primary vertex
Muon
Backward tracks
Requiring a gap, there is evidence for central exclusive productiondecaying to two muons.
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SB 18LHCb results: heavy flavours and QCD Trento, 15.09.11
Estimated feeddown
from χc
J/ψ and ψ’: number of photons
ψ’ feeddown
J/ψ and ψ’: number of forward tracks
ψ’ J/ψ J/ψ subtracted
J/ψ ψ’
Purity from forward track counting: fitting the background under the peak by using a straight line or exponential fit, yields purity estimate ~85%.
Exclusive production: signatures from J/ψ, ψ’ and χcLHCb 2010 data
3.1 ± 0.6 pb-1
LHCb 2010 data
3.1 ± 0.6 pb-1
χc
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SB 19LHCb results: heavy flavours and QCD Trento, 15.09.11
Fit elastic and inelastic components
Estimate purity below 900 MeV : 80±3%
Exclusive production: purity from dimuon pT spectrum
J/ψ and ψ’ signals
Clean mass peaks of J/ψ and ψ’ resonances despite looking at prompt production in pp-collisions at 7 TeV. Contribution from non-resonant background & misidentification is small
Events
wit
h
no b
ack
ward
tra
cks,
tw
o f
orw
ard
tra
cks
and n
o p
hoto
n.
J/ψ Ψ’
LHCb 2010 data
3.1 ± 0.6 pb-1
LHCb 2010 data
3.1 ± 0.6 pb-1
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SB 20LHCb results: heavy flavours and QCD Trento, 15.09.11
Require two forward tracks and one identified photon > 200 MeV. Even cleaner!
M(μμ) GeV/c2 M(μμγ) GeV/c2
Fit M(μμγ) to MC templates for ψ’, χc0, χc1, χc2
All the three χc states needed to describe the observed spectrum !
Exclusive production: χc states
LHCb 2010 data
3.1 ± 0.6 pb-1LHCb 2010 data
3.1 ± 0.6 pb-1
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SB 21LHCb results: heavy flavours and QCD Trento, 15.09.11* Large theoretical uncertainties. Rescattering corrections (alters cross-section by ~20%).
Exclusive production: results
Comparison theory-experiment requires major efforts from both parts. Reasonable precision for J/ψ and ψ’, systematics will be improved in 2011.
Consistent* with Starlight, SuperChiC, Motyka & Watt [Phys. Rev. D 78,
(2008) 014023] and Schaffer & Szcsurek [Phys.Rev. D76 (2007) 094014]
Still no precise determination of individual χc0, χc1, χc2 production.
Consistent* with SuperChiC, Harland-Lang et al. [arXiv:hep-ph/0909.4748]. Does not agree to CDF 2009 [Phys. Rev. Lett. 102, (2009) 242001].
Most clean ratio of ψ’ to J/ψ production, corrected for BR(ψμμ), 0.20 ±
0.03. Consistent with HERA and Tevatron results. Consistent* with Starlight and Schaffer & Szcsurek [Phys.Rev. D76 (2007)
094014. arXiv:hep-ph/0811.2488]
Contributions from all the 5 charmonium states (J/ψ, ψ’, χc0, χc1, χc2) is
seen.
New dedicated trigger line implemented now & statistics x 30 improvement in 2011 !
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SB 22LHCb results: heavy flavours and QCD Trento, 15.09.11
Charm studies: LHCb as LHCcC
Mixing parameter yCP via lifetime comparison
Search for CP violation via AΓ
(Search for direct CP violation) Moved to backup
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SB 23LHCb results: heavy flavours and QCD Trento, 15.09.11
Mixing and CP violation in charm sectorCharm is abundant at LHC: 6.5 mb cross-section. However need to reconstruct low pT decays.
Φ
|q/p|
SM
D*+
D
o(K
+K
- )π
+
195 pb-1
220 pb-1
Ds
+
K+K
- π+
D+
K+K
- π+
Large samples of charm mesons are being reconstructed. Presently ~700 pb-1 collected.
D1,2 = p |Do> ± q |Do>
x=m/, y=/2
Mixing in charm sector is non-zero at >5σ by HFAG, however no single measurement excludes 0.
CPV in mixing (SM or NP) driven by mixing parameters x,y (~1%). CPV in D mixing in SM is negligible, but can be enhanced in many models. Existing constraints are weak.
Direct CPV best looked for in CSD, where gluonic penguins are significant.
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SB 24LHCb results: heavy flavours and QCD Trento, 15.09.11
Charm mixing parameter yCP :
Future improvement in sensitivity : Statistics x30 in 2011 Improved treatment of background events
yCP= (5.5 ± 6.3 ± 4.1) x 10-3
Measurement of the charm mixing parameter yCPLHCb-CONF-2011-054
DoK-π+ DoK-K+
DoK-π+ DoK-K+τDo=410.2±0.9 fs
Contribution from BDX to prompt charm sample Correct lifetime bias on the event-by-event basis
HFAG 2011 average (without LHCb): (11.1 ± 2.2) x 10-3
2010 data, 28 pb-1, flavour tagging using Do sample from D*Doπ decays.
LHCb preliminary 28
pb-1
LHCb preliminary 28
pb-1
Challenges in time-dependent charm studies at LHC:
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SB 25LHCb results: heavy flavours and QCD Trento, 15.09.11
One of most important ways to search CPV in charm
mixing: 2010 data, 28 pb-1, flavour tagging using Do sample from D*Doπ decays.
Obtained event-by-event on data
HFAG 2011 average (without LHCb): ( 0.12 ± 0.25 ) x 10-2
AΓ= (-0.59 ± 0.59 ± 0.21) x 10-2
Measurement of AΓ LHCb-CONF-2011-046
Future improvement in sensitivity : Statistics x30 in 2011 Improved treatment of background events
Challenges in time-dependent charm studies at LHC:
Contribution from BDX to prompt charm sample
Correct lifetime bias on the event-by-event basis
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SB 26LHCb results: heavy flavours and QCD Trento, 15.09.11
Beauty studies: LHCb as LHCb
Angle : Evidence of suppressed ‘ADS’ mode BDK Charged hadron ID and
Direct CP violation in charmless B-decays with eyes
New results on b-baryons: ΛbDopK-
Bs mixing phase φs from BsJ/Ψφ and BsJ/Ψ fo(980)
Rare decays: Radiative penguines bs (Forward-backward asymmetry in BK*ℓℓ) Moved to
backup
Search for Bsμμ
Touch rare effects and mostly bs transitions: penguine or box diagram, NP diagrams can
compete.
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SB 27LHCb results: heavy flavours and QCD Trento, 15.09.11
B± DK± decays using common mode for Do &
Do γ sensitive interference different rates for B+ & B- (CPV)
Maximize interference by using mode suppressed for Do & favoured for Do
e.g. DoK+π- (DCS) , DoK+π- (CF) the ‘ADS’ method [Atwood, Dunietz, Soni]
Total visible BR very small (~10-7).
The suppressed ‘ADS’ mode is needed to access γ.
Precision CKM studies: angle γ
Rb Rt
1
The Rt side precision limited by theory (lattice calculations), while precision of γ limited by experiment. Improve precision of angle γ to improve CKM triangle closure check
Search for NP by comparing tree-mediated processes (γ, Rb) to those involving loop diagrams (γ, β, Rt)
B± (K π±) K±
±
2010
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SB 28LHCb results: heavy flavours and QCD Trento, 15.09.11
Signal seen with 4.0σ significance & hint of asymmetry, consistent with previous results
B± (K π±) K±
Ratio to favoured mode:
HFAG average (without LHCb):
(1.6 ± 0.3) x 10-2
B-(K+π-)K-
343 pb-1
Asymmetry: -0.58 ± 0.21
±
B+(K-π+)K+
343 pb-1
Evidence for suppressed ADS mode LHCb-CONF-2011-044
343 pb-1
HFAG average (without LHCb):
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SB 29LHCb results: heavy flavours and QCD Trento, 15.09.11
‘Bhh’ (h=π,K,p) at LHCb
Inclusive spectrum,ππ hypothesis
LHCb preliminary
Deploy RICH to decript ‘hh’ !
BoKπ Rely on good performance of trigger and RICH
Λbpπ
Two-body charmless B decays: significant contribution of penguin diagrams, important for NP searches
Boππ
BsKKΛbpK
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SB 30LHCb results: heavy flavours and QCD Trento, 15.09.11
BoK+π-
HFAG average (without LHCb):Most precise single measurement and first 5σ observation of CPV at hadron machine:
CDF result:0.17
First evidence of CPV in Bs decays:
Bd,sKπ: direct CPV LHCb-CONF-2011-042
In future perform time dependent study, particularly of BsKK: New Physics sensitive measurement of γ [e.g. Fleischer, PLB
459 (1999) 306]
BoK-π+
BsK+π-BsK-π+
320 pb-1 320 pb-1
320 pb-1320 pb-1
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SB 31LHCb results: heavy flavours and QCD Trento, 15.09.11
ΛbDopπ-
ΛbDopK-
New measurements with b -baryons LHCb-CONF-2011-036
ΞobDopK-
Cabibbo-suppressed decay ΛbDopK-, potentially powerful mode for measuring CKM
angle γ.
Normalization channel: ΛbDopπ-.
A signal with (stat+syst) significance of 2.6σ, consistent with decay.
ΞobDopK
-Relative production rate x BR: Mass relative to Λb:
Ξob [Ξ+
cπ-, Ξ+
cΞ-π+π-, Ξ-Λπ-, Λpπ-] recently observed by CDF
[arXiv:1107.4015].
Consistent masses from two experiments: MLHCb(Ξob) - MCDF(Ξ
ob) = -14.2 ± 7.7
MeV/c2
M(Dopπ-) MeV/c2 M(DopK-) MeV/c2
First observation of with significance of 6.3σ:
ΛbDopK-
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SB 32LHCb results: heavy flavours and QCD Trento, 15.09.11
Phase is small in SM (box diagram) : 0.0363 ± 0.0017 rad [CKMFitter] Deviations due to NP could be large
Precision CKM studies: Bs mixing phase φs from BsJ/Ψφ
Time dependent analysis Time resolution measured using prompt J/Ψ background: στ = 50 fs
LHCb measurement with 2010 data: 37 pb-1, 757 ± 28 signal candidates [LHCb-CONF-2011-006]
Tagging Need to tag initial flavour of the Bs Per event mistag calibrated on B+ J/Ψ K and Bd D* μ νμ
Dilution Dtag = 0.277 ± 0.011 ± 0.025 Tagging power εD2 = (2.08 ± 0.41)%
Angular analysis PVV decay: needs an angular analysis to resolve CP-even and CP-odd components Angular acceptance determined from MC Maximum deviation from uniform: 5%
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SB 33LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/ΨφΔ
Γs [
rad]
Φs [rad]
~770 decays
SM
Φs [rad]
First evidence (4σ) of ΔΓs > 0 !
φsJ/Ψφ = 0.13 ± 0.18 (stat) ± 0.07 (sys) rad
Γs = 0.656 ± 0.009 (stat) ± 0.008 (sys)
ps-1
ΔΓs = 0.123 ± 0.029 (stat) ± 0.008 (sys)
ps-1
337 pb-136 pb-1
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SB 34LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/Ψ fo(980)
First observation of BsJ/Ψ fo(980) (fo(980)ππ) by LHCb with 30 pb-1
[Phys. Letters B 698 (2011) 115] confirmed by Belle [Phys.Rev.Lett.106:121802,2011] and CDF [arXiv:http://arxiv.org/abs/1106.3682] With 330 pb-1 LHCb extractsφs.
The fo(980) looks pure scalar
no angular analysis needed.
330 pb-1
LHCb preliminary
330 pb-1
LHCb preliminary
330 pb-1
Bs J/ψ fo(980)
BoJ/ψK*BoJ/ψπ+π-
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SB 35LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/Ψ fo(980) and BsJ/Ψφ
φsJ/Ψfo(980) = -0.44 ± 0.44 ± 0.02
rad
φsJ/Ψφ+J/Ψfo= 0.03 ± 0.16 ± 0.07 rad
Or, combining, BsJ/Ψφ and BsJ/Ψ
fo(980) :
SM fit: 0.0363 ± 0.0017 rad
BsJ/Ψφ
BsJ/Ψ fo(980)
LHCb with 0.3 fb-1 already more sensitive, than CDF and D0
330 pb-1
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SB 36LHCb results: heavy flavours and QCD Trento, 15.09.11
Measure ratio of the branching fractions for BK* and Bsφ
Expect: 1.0 ± 0.2 from SM.
Radiative penguines: bs
Ali, Pecjak, Greub [Eur.Phys.J.C 55 (2008) 577]
LHCb-CONF-2011-055
Test for NNLO QCD predictions
Photons Broader signal peak than typical B decay
More work on backgrounds (B Kππo
etc) However, largest Bsφ sample
Bsφ
BK*340 pb-1
340 pb-1
Next: study time evolution and CP asymmetries
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SB 37LHCb results: heavy flavours and QCD Trento, 15.09.11
In SM, Bsμμ occurs only via loop diagrams, and is helicity suppressed:
BR(Bsμμ)SM = (3.2 ± 0.2) x 10-
9 [A.J.Buras, arXiv:1012.1447]
Can be strongly enhanced in NP models, especially those with extended Higgs sector.
E.g. MSSM: NUHM (= generalised version of CMSSM) [O. Buchmuller et al, arXiv:0907.5568]BR(Bsμμ) - highly discriminatory
Recent CDF result with 7 fb-1:
[arXiv:1107.2304]
Search for Bsμμ
BR(Bsμμ) = (1.8 ) x 10-8
or < 4.0 x 10-8 @ 95% CL
+1.1-0.9
LHCb 2010 data, 0.037 fb-1:
[PLB 699 (2011) 330]
BR(Bsμμ) < 5.6 x 10-8 @ 95% CL
Many previous measurements
Talk by M.Kraemer
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SB 38LHCb results: heavy flavours and QCD Trento, 15.09.11
Similar to 2010 analysis [PLB 699 (2011) 330]
Select Bsμμ, using Boosted Decision Tree out of 9 kinematical and topological variables
BDT tuned on MC, but calibrated on data:
Bhh, triggered on ‘other B’, and sidebands Calibrate invariant mass resolution (~25 MeV) on data (dimuon resonances & Bhh)
Look on 6 x 4 grid of μ+μ- invariant mass vs.
BDT output
Normalize to: B+J/ΨK+, BsJ/Ψφ
and
BoKπ– all give
consistent results
Search for Bsμμ, LHCb 2011 data, 300 pb-1 LHCb-CONF-2011-037
300 pb-1
300 pb-1 300 pb-1
300 pb-1
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SB 39LHCb results: heavy flavours and QCD Trento, 15.09.11
Combinatorial background
Data
Bhh misid background
0.1±0.1events ineach of 4BDT bins
Signal with SM BR
Search for Bsμμ, LHCb 2011 data, 300 pb-1
LHCb preliminary
300 pb-1
LHCb preliminary
300 pb-1
LHCb preliminary
300 pb-1
LHCb preliminary
300 pb-1
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SB 40LHCb results: heavy flavours and QCD Trento, 15.09.11
Compute limits using frequentist CLs method and LHCb combined result for fs/fd
expected: background only±1σobserved
±1σobserved
Search for Bsμμ, LHCb limits
Expected limit assuming bkg only (95% CL) 1.0x10-8 3.1x10-9
Expected limit assuming bkg + SM signal (95% CL) 1.5x10-8
Observed limit (95% CL) 1.6x10-8 5.1x10-9
p-value of background only hypothesis 14% 79%
Observed limit, 2010+2011 (95% CL) 1.5x10-8
BR(Bsμ+μ-
)
BR(Bdμ+μ-)
LHCb preliminary
300 pb-1
LHCb preliminary
300 pb-1expected: background and signal SM BR
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SB 41LHCb results: heavy flavours and QCD Trento, 15.09.11
A preliminary CMS (1.14 fb-1)-LHCb (0.34 fb-1) combination on
BR(Bsμ+μ-) has been performed, again using the CLs approach,
& taking LHCb value of fs/fd as common input
CMS + LHCb preliminary
±1σobserved
Observed candidates in both experiments are consistent with the sum of
backgrounds and SM signal BR < 1.1 x 10-8 @ 95% CL. This limit is 3.4 times the expected SM value. A BR of 1.8 x 10-8 has a CLs value of ~0.3%
Search for Bsμμ, combining LHCb and CMS results
LHCb (0.34 fb-1) + CMS (1.14 fb-
1) preliminaryexpected: background only
LHCb-CONF-2011-047
CMS PAS BPH 11-019
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SB 42LHCb results: heavy flavours and QCD Trento, 15.09.11
Hunting for physics Beyond Standard Model (“New Physics”) continues
and
either we discover it within our lifetime scale
or …
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SB 43LHCb results: heavy flavours and QCD Trento, 15.09.11
… and New New Physics == Beyond New Physics
discover on our own.
... or we have to ask for help this time ...
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SB 44LHCb results: heavy flavours and QCD Trento, 15.09.11
Summary
LHCb is proving to be a heavy flavour factory
Production of quarkonia and open heavy flavour hadrons is being systematically studied
Charm cross section is large, huge D-meson samples collected, and first CPV studies with 2010 data look promising
Precision CKM angle studies are launched, hint on the ‘ADS’ asymmetry in BDK is observed
Most precise measurement of the direct CPV in BKπ
First evidence of the direct CPV in BsKπ
New data on the b-baryons
LHCb and CMS do not confirm the hint seen by TEVATRON for
Bsμμ, and set the limit, which is x 3.4 SM value
2011 data being analysed, many analyses still on 2010 data
Expect 1 fb-1 in 2011, more in 2012, setting the scene for
precision rare effects studies
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SB 45LHCb results: heavy flavours and QCD Trento, 15.09.11
Backup
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SB 46LHCb results: heavy flavours and QCD Trento, 15.09.11
37 pb-1
2010
370k decays
Compare with 43k events in BABAR, 80 fb-1 [PRD 71 (2005) 091101 (R)]
Normalize D+ vs. D- to remove production
asymmetries Use resonance motivated binning & uniform binning
Look for statistically significant difference in D+
vs. D- bin contents (based on PRD 80 (2009)
096006) Look for fake CPV in sidebands and control modes
No evidence of CPV for signal in any binning
Cabibbo favoured control modes (no CPV
expected)
No fake CPV seen: data & method robust against biases
Same topology Ds+K+K-π+
10x more abundant D+K-π+π+
Direct CPV search Paper in preparation
Perform model independent binned CPV search in singly Cabibbo suppressed D+K-K+π- events
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SB 47LHCb results: heavy flavours and QCD Trento, 15.09.11
BK*μμ
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SB 48LHCb results: heavy flavours and QCD Trento, 15.09.11
b l l s, very rare in the SM BR (B l l K*) = (3.3 ± 1.0) x 10-6
Sensitive to Supersymmetry, any2HDM, Fourth generation, Extradimensions, Axions . . .
Ideal place to look for new physics
b l l s
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SB 49LHCb results: heavy flavours and QCD Trento, 15.09.11
Angular Distributions & AFB
Many observables depending on q2 = m2μμ c4
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SB 50LHCb results: heavy flavours and QCD Trento, 15.09.11
[Krüger & Matias][Egede et al.] [Ali et al.]
Models probed by AFB(q2)
dependence
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SB 51LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb presents a result with 300 events with 309 pb-1: Largest sample in the world [LHCb-CONF-
2011-038]
Select events B0K*μ+μ- using
Boosted Decision Tree from sample of 309
pb-1 Veto decays in J/Ψ and Ψ(2S) (used as
control of angular fits) Weight events according to η-
1(θl,φ,θK,q2)
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SB 52LHCb results: heavy flavours and QCD Trento, 15.09.11
B0K*μ+μ-Measure in 6 q2 bins:
extract dГ/dq2
SM: Bobeth et al., [arXiv:1105.0376]
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SB 53LHCb results: heavy flavours and QCD Trento, 15.09.11
Fit for θK and θl
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SB 54LHCb results: heavy flavours and QCD Trento, 15.09.11
AFB in B0→K*μ+μ-in LHCb with 309 pb-1
Systematic uncertainties are small, and generally themselves statistics limited.
LHC
b-C
ON
F-20
11
-03
8
Data are consistent with SM at present sensitivity.
Add other observables, e.g. AT(2), sensitive to RH currents
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SB 55LHCb results: heavy flavours and QCD Trento, 15.09.11
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SB 56LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/Ψφ
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SB 57LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/Ψφ
Tagging Need to tag initial flavour of the Bs Per event mistag calibrated on B+ J/Ψ K and Bd D* μ νμ
Dilution Dtag = 0.277 ± 0.011 ± 0.025
Tagging power εD2 = (2.08 ± 0.41)%
Angular analysis PVV decay: needs an angular analysis to resolve CP-even and CP-odd components Angular acceptance determined from MCMaximum deviation from uniform: 5%
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SB 58LHCb results: heavy flavours and QCD Trento, 15.09.11
φs from BsJ/Ψφ: fit projections
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SB 59LHCb results: heavy flavours and QCD Trento, 15.09.11
Miscellaneous
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SB 60LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb also measures the double J/ψ cross section: [LHCb-CONF-2011-009], submitted to
Phys.Lett.B5.1 ± 1.0 ± 1.1 nb-1
Model: [hep-ph/0603175]
37.5 pb-1
Sensitivity to tetraquarks, built of c-quarks
Only statistical errors shown.
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SB 61LHCb results: heavy flavours and QCD Trento, 15.09.11
LHCb operation: luminosity limitations
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SB 62LHCb results: heavy flavours and QCD Trento, 15.09.11
J/ψ μμ
ψ(2S) μμ
ψ(2S) / J/ψ
15% theo. uncertainty assumed
15% theo. uncertainty assumed
Deviation significance, [σ]
Exclusive production: results