1

Steven BluskSyracuse University

Introduction to LHCbNominal vs 2010Early signalsPhysics: 0.1 – 1.0 fb-1

Conclusions

Introduction to LHCbNominal vs 2010Early signalsPhysics: 0.1 – 1.0 fb-1

Conclusions

For leptonic final states,see talk by Liming Zhang.

LHCb Early Results and Prospects:

Hadronic Final States

2

Introduction

New Physics particles should couple to quarks. Whatever is responsible for EWSB, is also likely responsible for the physics of flavor, e.g. Yukawa couplings, CKM matrix, etc.Surprisingly, no clear signs yet

Intensive study of loop diagrams in decays of flavor necessary.

Possibly the ‘discovery path’ to NP.It’s not only about the mass scale, but also the couplings to SM particles.Precision flavor physics will lead to discovery or stringent constraints on NP.

Probably worth the reminder:Absence of FCNC charm quarkΔmK charm massΔmb top massεK 3rd generation of quarks

3

The LHCb Experiment

• Beams (intentionally) less focused Lint ~ 2 x 1032cm-2s-1 (nominal)

mostly single interaction.

• Forward, correlated bb productionSingle arm forward spectrometer 12 mrad <θ< 300 mrad (1.9<η<4.9)

• 100K bb/sec expected All B-hadron species produced:

• B0, B+, Bs, Bc, b-baryons.• Yields ~102 - 106 / channel per 2 fb-1

• σb/σtot ~ 10-2, + Interesting BFs ~ 10-4 – 10-7

Interesting events ~ 10-6 to 10-9 (or less) Highly selective trigger needed !!~2 kHz written to disk

LHCb: dedicated heavy flavour experiment to search for new physics in CP-Violation and Rare Decays

100 μb230 μb

bb production cross section at √s=14 TeV–

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The detector VeLo(precisiontrackingnear IP,

trigger on IP)

VeLo(precisiontrackingnear IP,

trigger on IP)

RICH1(PID: p,K,π)

RICH1(PID: p,K,π)

TT(Si Tracking)

TT(Si Tracking)

Dipole4.1 T m

σp/p~0.5%

Dipole4.1 T m

σp/p~0.5%

IT/OT(Si/StrawTracking)

IT/OT(Si/StrawTracking)

RICH2(PID:p,K,π)

RICH2(PID:p,K,π)

ECAL/HCALTrigger,

PID: (e,γ,π0,η,h...)

ECAL/HCALTrigger,

PID: (e,γ,π0,η,h...)

PRS/SPD(PID: e,γ,π0)PRS/SPD

(PID: e,γ,π0)

MUON(Trigger &

μ PID)

MUON(Trigger &

μ PID)

5

Brief snapshot of physics in LHCb

World class measurements with charm, beauty in 2010-11 run!

1 nb-1 1 pb-1 1 fb-1 10 fb-1100 pb-1

Inclusive Particle Production: π, K, p, p, Ks, φ, Λ, Λ, D, Ds, Λc, J/ψ, B, Bs, Bc, Λb…

Charm: D Mixing, CPV, rare decaysBottom: sin(2β), Δms, B Xlν, etc

Bottom: sin(2βs), Β DK, Bs μμ, B K*ll, Bs φφ, rare decays, etcExotic: Hidden valley, etc

We are here

2010-2011 run Will be approaching LHCbdesign luminosity in 2011

6

2010: Exploiting Minimum Bias Data

108 minimum bias @ 2kHz

Number of selected signal events:

LHCb at ~3x108 ev. now

Clearly, lots of old friends should be dropping in !

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LHCb Trigger - Normal vs Low Lumi

2 kHz to tape

L0 e, γ

40 MHz

1 MHz

L0 had

L0 μ

ECALAlley

Had.Alley

Global reconstruction30 kHz

MuonAlley

Inclusive selections:topological, μ, μ+track,

μμ, D→X, ΦExclusive selections

L0:Hardware

HLT1:Confirm L0pT, IP

HLT2:Inclusive & Exclusive channelselections

Normal (2x1032)Optimized for B PhysicsNormal (2x1032)

Optimized for B PhysicsLow luminosity

runningLow luminosity

running

Pass-thru (rate<2 kHz)Being phased in (rate > 2 kHz)Relaxed IP cuts: εcharm ~ 4-5X larger over nominalεb also increased substantially

Very low ET, pT cutsTil now, save “everything”(Rate < 2 KHz)

Phase in for25 kHz < rate < 300 kHz

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2010 RunningE = 3.5 TeV: Not an issue for LHCb

σbb only reduced by ~ 2Gain back some with lower triggerthresholds, lower background, etc.

Detector calibrations, with and without resonances.

Alignment, B field, PID, misID, etcTune up generator & detector simulation

Event mult, material, etc(Re)tune HLT algorithms on min bias data

Nominal tune for 2x1032, optimized for b physics Retune for lower lumi running

Looser IP cut larger charm trigger eff.Modest gains in b trigger efficiency too

Let’s have a look at some signals from the 2010 data.. LHCb preliminary

D0 from D*

0

2000

4000

6000

8000

10000

12000

14000

16000

1 3 5 7 9 11 13 15 17 19 21 23Fill

μb-1

Delivered Luminosity

Recorded Luminosity

May 21

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Long-lived Strange Resonances~65 μb-1

(<1% of sample)

Ks π+π−

Λ pπ−

Ξ Λπ−

Calibrations: p,π μ, π Κ misIDPhysics: Cross-section, asymmetries, etc

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(Mostly) prompt strange resonance (φ)

K/π separation using RICH critical

Huge sample PID calibration Tests/calibrations of

inclusive φ trigger.

~65 μb-1

(<1% of sample)φ K+K-

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Open charm

~800 μb-1

(~4% of sample)

D0 Κ−π+

1539±46

First, the standard candles

D+ Κ−π+π+

566±15

Λc pΚ+π−

53±9

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More open charm

~800 μb-1

(~4% of sample)

D0 Κ+Κ−

125±14

D0 Κ−π+π0

63±11

D+, Ds+ K+K-π+

48±8

59±8

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Charm - Scaling Up to 100 pb-1

Mode Yieldin 0.8 nb-1

Yield (106) for 100 pb-1

D0 Kπ 1539±46 ~150D0 Kπ, D* tag 260±17 ~26D0 KK 125±14 ~13D0 KK, D* tag 21±5 ~2D+ Kππ 566±15 ~60D+ KKπ 48±8 ~5Ds

+ KKπ 59±8 ~6Λc pKπ 53±9 ~5

Rou

gh sc

alin

g

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Charming Opportunities

2 1M Mx −=

ΓW-

c u

u c

W+-

dsb

dsb

2 1

2y Γ − Γ

=Γ

KK,ππ..D0 0D

0 0 0 01 2

Mass Eigenstates:

D p D q D D p D q D= + = −

Charm mixing now well established.

x (%)

no mixing

y (%

)

Next big holy grail is to seek CPV in charm… Either in mixing or directdecays… Current bounds weak..

Any non-zero result New Physics

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LHCb will have ~20X larger sample with 0.1 fb-1

Should be able to achieve:δyCP ~ 0.1 % (stat only)δAΓ ~ 0.1 % (stat only)

Will improve CPV allowed region

LHCb will have ~20X larger sample with 0.1 fb-1

Should be able to achieve:δyCP ~ 0.1 % (stat only)δAΓ ~ 0.1 % (stat only)

Will improve CPV allowed region

D0 KK / D0 KπConsider the two measureables They provide constraints on |q/p| and

φ = Arg(q/p)

2 cos sin

2 cos sin

CPq p q py y xp q p q

q p q pA y xp q p q

φ φ

φ φΓ

⎛ ⎞ ⎛ ⎞= + − −⎜ ⎟ ⎜ ⎟

⎝ ⎠ ⎝ ⎠⎛ ⎞ ⎛ ⎞

= − − +⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

Bel

le, P

RL

98 (2

007)

211

803

540 fb-1 ~105 D0 K+K- (from D*) stat precisions δyCP = 0.32 % δAΓ = 0.30 %

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Direct CPV

• Singly Cabibbo Suppressed decays – significant contributionfrom Penguins possible contributions from New Physics

Excellent candidate: D+→K+K-π+ with Ds+→K+K-π+ & D+→K-π+π+ as control channels

Total asymmetry, and A across the Dalitz plot.Expect ~5 million D,Ds KKπ events in 100 pb-1

Order of magnitude larger than current B-factories samples.

?

D+→KKπDs→KKπ

D+→Kππ

~0.8 nb-1

Ds→KKπ

( ) ( )( ) ( )D K K D K KAD K K D K K

π ππ π

+ + − + − + − −

+ + − + − + − −

Γ → − Γ →=

Γ → + Γ →

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Δms (200 pb-1)

Expected yieldin 0.2 fb-1 @3.5 TeV~5 K Bs Dsπ

δ(Δms) ~ 0.04 (stat only)(~2.5X smaller stat. error, comparable stats)

LHCb - Toy MC

εD2 ~ 6.2%σt ~ 40 fs

Clear resolution of rapidBs oscillations!

CDF (2006) 1 fb-1

Hadronic modes~2000 Bs Ds(φπ)π~3100 partially recon.

εD2 ~ 5%σt ~ 100 fs

Δms=17.77±0.10±0.07 ps-1

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As we approach 0.5-1 fb-1

CKM paradigm provides the majorityof CP violation inflavor.

Significant room for NP.Hints from sin(2βs)?Recent Asl from D0?

1 fb-1

Final state common to D0 & D0

allows for interference → γ

Kπ, KK, ππ, Kπππ, Kππ0 ,K0

Sππ, K0SKK, …

Time independent + time-dependent modes:Expect σγ~7o with ~1 fb-1 from LHCb

Vub ~ e -iγ

One B± decay mode for extracting γ:

10 fb-1

Latest B-factory results (B DK, D Ksππ):( )

( )

10.811.6( :1003.3360) 78.4 3.6

( :1005.1096) 68 14 4

8.9

3

o

o

Belle arXiv

BaBar arXiv

+−⇒ ± ±

⇒ ± ± ±

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Closer to 1 fb-1: Bs φφPenguin loop diagram.=> Interference of direct decay and mixing

Vts appears in both decay and mixing.=> cancellation of SM contribution of amplitudes

=> (VtbV*ts/V*

tbVts) (V*tbVts/VtbV*

ts) ~ 1mixing decay

=> But, new physics unlikely to cancel

Prediction of CP violation in SM < 1%.=> Observation of any CP violation is signature for NP.

Again, decay to two vector particles requires an angular analysis to extract CP asymmetries.

Sensitivity:

1 fb-1@7TeV ~ 1K events, σ(2βs)φφ ~ 0.25 rad

10 fb-1@14TeV: ~20K events ~ 0.06 rad

bt s

s

s

W–Vtb Vts*

s s

φ

φ

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Conclusions

LHCb off to a great startDetector operating well. We see the particles we expected.

Min Bias trigger til now (<2 kHz inter. rate)HLT1 to be unleashed, can no longer “save everything” (2-25 kHz )HLT1 & HLT2 when collision rate (25-300 kHz)

First year will be devoted to:Fine tuning MC sims, detector calibrations, alignment, etcParticle production cross-sections from π to b, lifetimes, and beyond !A lot of open and closed charm physics (D, Ds, X,Y, & Z J/ψX…).Establish first key B decays in core physics channels (too many to list!)

New Physics could come early in LHCb [O(1 fb-1)]γ, sin(2βs), Bs μμ, Afb in K*ll, etc

Now, let’s make history !