flavor physics at lhc and tevatron - home.kias.re.krhome.kias.re.kr/psec/monthly/intae.pdf · lhc...

Intae Yu

Sungkyunkwan University

LHC Physics Monthly Meeting @ KIAS , Aug 6th, 2011

Flavor Physics at LHC and Tevatron

Reference: EPS2011 talks by G. Wilkinson, D. Tonelli, F. Deliot, and many others

LHC Physics Monthly Meeting @ KIAS , Aug 6th 2011 2

Accelerator Operation

LHC delivered 1.5 fb-1 and ~5 fb-1 expected by the end of 2011

Inst. Lum = 1.7 ×1033 cm-2 s-1 (2011.7)

Tevatron is expected to deliver 12 fb-1 by Sep 30, 2011

Inst. Lum = 4 ×1032 cm-2 s-1 (2011.7)


Particle Detectors at Tevatron

New

Old

Partially

new

Forward

muon

Endplug

calorimeter

Silicon and drift

chamber trackers

Central muonCentral

calorimeters

Solenoid

Front end

Trigger

DAQ

Offline

TOF

D0 DetectorCDF Detector

CDF with better tracking and Particle Identification (PID)

D0 with better calorimetry and lepton coverage


Particle Detectors at LHC

CMS Detector ATLAS Detector

CMS with better tracking and electromagnetic calorimetry

ATLAS with better hadron calorimetry


LHCb Detector at LHC

LHCb optimized for flavor physics

Dedicated heavy flavor trigger, precise vertexing, excellent PID (RICH)

LHCb operating luminosity (3×1032cm-2s-1) << LHC design luminosity

Reduce multiple interactions → less combinatoric background

LHCb Detector


Heavy Flavor Production


Quarkonium Production at LHC – J/ψ(nS), Υ(nS)

Large cross sections of quarkonium production

→ Help to understand production mechanism (color singlet? octet?..)

Differential cross section measurement using 2010 data (~37 pb-1)

More to come using 2011 data (polarization, higher states,…)

J/ψ

Upsilon


Quarkonium Production at LHC - χc

Reconstruction of χc →J/ψγ using conversion electrons from γ

Relative Production of χc1 and χc2 do not agree with theoretical

predictions


Quarkonium Production – X(3872)

Measurement of relative production of ψ(2S) and X(3872) at CMS

R = 0.087±0.017(stat)±0.009(syst) from 2010 data (~40 pb-1 )

Mass measurement at LHCb

MX(3872) = 3871.96±0.46(stat)±0.10(syst) MeV/c2 from 2010 data

(3871.61±0.16(stat)±0.19(syst) MeV/c2 from CDF)

CDF

2.4fb-1


Quarkonium Production – X(4140)

Narrow resonance in m(J/ψKK) – m(J/ψ) observed at CDF

in B+→J/ψφK+ decays with significance of ~ 3.8

LHCb does not confirm this structure yet

→ 2.4 difference from CDF result

14±5 events


b-Quark Production at LHC

b production studies through various channels (dileptons, J/ψ,..)

Good agreements with Fixed Order NLL QCD predictions


b-Quark Fragmentation at LHCb

Measure b fragmentation fractions using exclusive decays of B and

Bs mesons and inclusive decays of B → DμX at LHCb

( from LEP and Tevatron)0.021

0.020ds 0.267/ff

0.0270.271/ff ds


Bottom Baryons at Tevatron

Reconstruct Ξb-(0) through cascade decays

with , , and

Mass measurement of Ξb-(0)

M(Ξb0 ) = 5787.8±5.0(stat)±1.3(syst) MeV/c2

M(Ξb0 ) - M(Ξb

- ) = 3.1±5.6(stat)±1.3(syst) MeV/c2

cb)( c

p


Bottom Baryons at LHCb

First observation of Λb →D0 p K- ( another mode for γ measurement)

Evidence of Ξb0 → D0 p K- ( consistent with CDF mass, ~2.6σexcess)

)()(019.0±112.0=)→Λ(

)→Λ(011.0+

014.00

0

syststatπpDBr

pKDBr

b

b

)(08.0±)(12.0±29.0=)→Λ(×

)→Ξ(×

0

Λ→

00

Ξ→

0

0

syststatpKDBrf

pKDBrf

bb

bb

b

b


B Decays


B → DK Decays

B → DsupK ADS Analysis (Dsup→ K+π-, Dfav→ K-π+ )

Interference between B- → D0 K- → [K+π-]K-

and B- → anti D0 K- → [K+π-]K- Cleanest way to measure γ

Observables (Rads : Ratio to favored mode, Aads : Asymmetry)

Rads = (22.0±8.6±2.2)×10-3 (CDF), (16.6±3.9±2.4)×10-3 (LHCb), (16.0±3.0)×10-3 (world)

Aads = -0.82±0.44±0.09 (CDF), -0.39±0.17±0.02 (LHCb), -0.58±0.21 (world)


Two-body Chamless B Decays at CDF

Two-body charmless B decays Sensitive to CKM angle γsignificant contribution from penguin decays provides sensitivity to new physics (NP)

First evidence for Bs →π+π-

Br = (0.57±0.15(stat)±0.10(sys))×10-6

Agree with pQCD estimates

First bounds for B →K+ K-

Br ∈ [0.05, 0.46] ×10-6 @ 90% CL


Two-body Chamless B Decays at LHCb

Acp(B0 → Kπ) = -0.088±0.011±0.008

Consistent with world average -0.098±0.011

Acp(Bs0 → Kπ)

= 0.27±0.08±0.02 (0.39±0.17 @ CDF)

Excellent PID using RICH at LHCb


B0 →K*μ+μ- Decays

AFB consistent with SM @ LHCb can determine cross point sensitive to NP

Probe helicity structure in B0 →K*μ+μ- and search for NP especially forward-backward asymmetry (AFB) as a function of lepton invariant mass (q2)

~300 K*ll events


Bs Mixing Phase

Analysis is under progress using ~ 350 pb-1 @ LHCb Sensitivity to be improved by including CP-eigenstate Bs → J/ψf0(980)

CPV phase φs in Bs → J/ψφ probes NP Earlier CDF results show some deviation (~ 2σ) from SM

0.8σfrom SM

1σfrom SM


Dimuon Charge Asymmetry at D0

Updated results from D0 (impact parameter dependent analysis)

Absl = (-0.787±0.172(stat)±0.093(syst)) × 10-2

D0 reported the anomalous like-sign charge asymmetry using 6.1fb-1

,

Absl = (-0.957±0.251(stat)±0.146(syst)) × 10-2

bb

bbb

slNN

NNA

s

sls

d

sld

b

sl aCaCA

3.2σfrom SM3.9σfrom SM


Bs/Bd → μ+μ- at CDF

Br(Bd → μ+μ-) < 6×10-9 @ 95% CL (SM prediction 1.1×10-10 )

Br(Bs → μ+μ-) ∈ [0.46,3.9]×10-8 @ 90% CL (SM prediction 3.2×10-9 )

Assuming signals, Br(Bs → μ+μ-) = 1.8+1.1-0.9×10-8 (~ 2.8σ)

SM rate is small and well understood. NP can enhance the rate.

Updated CDF analysis : improved Neural Network (NN) and more data


Bs/Bd → μ+μ- at CMS

Br(Bd → μ+μ-) < 4.6×10-9 @ 95% CL

Br(Bs → μ+μ-) < 1.9 ×10-8 @ 95% CL ( CDF 1.8×10-8 )

Cut-based Analysis

1.14 fb-1

No excess observed


Bs/Bd → μ+μ- at LHCb

Br(Bd → μ+μ-) < 5.2×10-9 @ 95% CL

Br(Bs → μ+μ-) < 1.5 ×10-8 @ 95% CL ( CDF 1.8×10-8 )

Boost Decision Tree (BDT) out of 9 kinematical and topological variables

Train BDT on MC, Calibrate on data (sidebands, B→hh)


Top Physics


Top Quark Production at LHC

Top quark pair production via gluon fusion At Tevatron, quark-antiquark annihilation dominates

Top events are classified by the W decay modes


Top Quark Production at LHC

Measurements of the cross section agree with QCD predictions

l+jets

dilepton


Single Top Production

Single top production via electromagnetic interaction

s channel t channel Wt channel

t channel contribution is dominant at LHC.

Measure single top production in each channel using event structures


Single Top Production

Multivariate methods are used to discriminate signals from backgrounds and other single top events.


Top Quark Mass

Tevatron combination gives an uncertainty below 1 GeV

New electroweak fit constraints on Higgs mass (< 161 GeV/c2 @95% CL)


Top-AntiTop Charge Asymmetry

NLO QCD predicts an asymmetry for produced via annihilation Top quark is emitted along the direction of incoming quark Exchange of new particles can modify the asymmetry

tt qq

forward-backward asymmetry center - forward asymmetry


Top-AntiTop Charge Asymmetry at Tevatron

CDF measured the and Δy dependence of the asymmetry Larger asymmetry observed in high mass and large rapidity difference

D0 gives results consistent with CDF

ttM

CDF l + jets CDF l + jets(M tt>450 GeV)

CDF dilepton D0 l + jets

Data 0.158±0.074 0.475±0.114 0.42±0.16 0.196±0.065

NLO QCD 0.058±0.009 0.088±0.013 0.06±0.01 0.05±0.01


Top-AntiTop Charge Asymmetry at LHC

LHC results are consistent with SM prediction

Different variables : ATLAS (Δy), CMS (Δη)


Summary

LHC experiments, especially LHCb, begin to produce physics results comparable to or better than Tevatron results on heavy flavor frontier.

LHC accelerator has delivered 1.5/1.5/0.5 fb-1 and is expected to deliver 5/5/1 fb-1 to CMS/ATLAS/LHCb experiments respectively.

Some anomalies in dilepton charge asymmetry and top pair charge asymmetry are observed although their significances are not large yet

More interesting results will be expected from LHC by 2012 when the size of data is increased almost by 10 times.

flavor physics at lhc and tevatron - home.kias.re.krhome.kias.re.kr/psec/monthly/intae.pdf · lhc...

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