Highlights from the LHCb Experiment

UFRJ

Highlights from the LHCb Experiment

SILAFAE 2012

Kazu AkibaUFRJ-Brazil

On Behalf of the LHCb Collaboration

UFRJ

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ContentsB physics at the LHC.The LHCb Experiment.LHCb physics results

Bs->μ+μ γ from B->DK B->hhh D mixing pA Run TOO MANY!!!(82 papers submitted, over 100 conference notes ) List: http://cdsweb.cern.ch/collection/LHCb%20Papers?ln=en

The UpgradeConclusionNot Covered: Posters!

BJ/ΨKs decays -- Daniela Szilard Le Cocq D'Oliveira The LHCb’s Jet Reconstruction -- Oscar A. A. Francisco Electroweak studies at LHCb -- Valdir S. Guimaraes

Kazu Akiba SILAFAE 12.12.12

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B Physics at the LHC

Kazu Akiba SILAFAE 12.12.12

π+Bs0

μ-

Ds-

Beam 2Beam 1

PV

IP

A hadron collider provides many B particles to study:

High b and c production cross section at the TeV scales.

Also provides B and D particles with a high boost. Long lived particles can be distinguished from the prompt ones.

Production at low angles…But also high background rateRequirements:

Good vertex, IP resolution. Good particle identification. Highly selective trigger

bb production along the beam axis.

_

σ(pp→bbX) = 75 ± 14 μb *

* Phys. Lett. B 694 (2010) 209

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The LHCb Experiment

Kazu Akiba SILAFAE 12.12.12

Large Hadron Collider beauty Experiment for CP violation and Rare B Decays.

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The LHCb Experiment

Kazu Akiba SILAFAE 12.12.12

TTSi

Muon

MWPCGEM

HCAL

ECAL RICH2 Outer Tracke

r straw Tubes

Magnet

RICH1

VELO&PUSi

Inner Tracke

r Si

+ TriggerHard &

Soft

Large Hadron Collider beauty Experiment for CP violation and Rare B Decays.

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The LHCb Experiment

Kazu Akiba SILAFAE 12.12.12

TTSi

Muon

MWPCGEM

HCAL

ECAL RICH2 Outer Tracke

r straw Tubes

Magnet

RICH1

VELO&PUSi

Inner Tracke

r Si

+ TriggerHard &

Soft

Zoom in the vertex

region

Closes for

physics

Open during

injection

Large Hadron Collider beauty Experiment for CP violation and Rare B Decays.

UFRJ7Kazu Akiba

The LHCb Experiment

Large Hadron Collider beauty Experiment for CP violation and Rare B Decays.

μ

K, π

n

γ

e-

pp

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UFRJ8Kazu Akiba

LHCb in Numbers

Great Vertex Resolution! Primary/secondary separation, proper time resolution.

Excellent momentum and mass resolution.Outstanding PID (K-π) and μ reconstruction.Dedicated Trigger system for B and C!

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UFRJ9Kazu Akiba

Operations

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High Efficiency!

Over 2/fb acquired this year! More than 3/fb integrated

Operating at 4x the designLuminosity / bunch

All to provide MANY physics results…(Most of results presented here with 2011 Data alone)

UFRJ10Kazu Akiba

Bs μ+μ-

Very small branching ratio, but very well predicted in the Standard model: (3.54±0.30) x 10-9

But possibly enhanced by new physics:

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SM NP

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Bs μ+μ- AnalysisA multivariate analysis strategy using a BDT method to discriminate signal/background.

main background bb->μ+μ-X special care with Bhh’ (h(‘)μ)Peaking backgrounds well modelled.

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UFRJ12Kazu Akiba

Bs μ+μ-

EvidenceBR(Bs μ+μ-) = (3.2-

1.2+1.5 )x10-9

3.5 s excessCompatible with standard

model2011 + ½ 2012 (2.1/fb)1/fb left to be analysed.LHCb-PAPER-2012-043

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UFRJ13Kazu Akiba SILAFAE 12.12.12

Bs μ+μ- Candidate event

@ >0.8 BDT

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Approaching γThe least precisely measured angle in the CKM

unitarity triangles: B factories σ ~15-16o (see CKM2012 WG:V )

Direct measurements require the observation of very suppressed channels (Vub)

It requires the delicate observation of interference

LHCb has the capability ofmeasuring γ in a wide varietyof channels with contributionsfrom tree diagrams or penguin.

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BDK

BDK family provides a theoretically clean lab to measure γ.

Several different observables f provide independent measurements .

The increasing statistics of LHCb will populate the suppressed decays required for an over constrained measurement of γ.Kazu Akiba SILAFAE 12.12.12

Where f can be: Kπ, KK, ππ, Kπππ, Ksππ, KsKK, Kππ0 …

→ f

→ f

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B0D0K0*First observations of very suppressed channel!2011 dataset (LHCB-CONF-2012-024)

Shows already some CP violation.Asymmetry A (KK) = -0.47 +0.24

-0.25 ±0.02 (sys)

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UFRJ17Kazu Akiba

B+D0K+

Combination of the ADS/GLW and GGSZ (Dalitz) give the LHCb’s constraint on γ = (71 +16

-15 )o

(CERN-LHCb-CONF-2012-032)

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B+ DK+ , with D hh [GLW/ADS*] PLB 712 (2012) 203B+ Dπ+ , with D hh [GLW/ADS] PLB 712 (2012) 203B+ DK+ , with D Ks hh [GGSZ] arXiv 1209.5869B+ Dπ+ , with D Ks hh [GGSZ] arXiv 1209.5869B+ DK+ , with D πKππ [ADS*] LHCb-CONF-2012-30B+ Dπ+ , with D πKππ [ADS*] LHCb-CONF-2012-30B+ DK+ππ , with D hh [GLW*/ADS] LHCb-CONF-2012-21 B0 (s) DK*0 , with D hh [GLW/ADS] LHCb-CONF-2012-24B0 (s) DKK with D hh [GLW/ADS*] PRL 109 (2012) 131801* First observations

UFRJ18Kazu Akiba

BhhhDisclaimer: Charged B and charged h…Access to t → s,d (Penguin) and

the CKM phase γ b → u (Tree) interfering diagrams.

CP violation expected from interference between tree and penguin diagrams.

CP violation expected also from interferences between resonances in the phase space.

A complete analysis of the CP asymmetries in the phase space is needed for a complete understanding.

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UFRJ19Kazu Akiba

ACP in BhhhMeasuring a a few combinations of final

states:B+Kππ , B+KKK , B+πππ , B+KKπLHCb-CONF-2012-018, LHCb-CONF-2012-028

Assymetries observed and well controlled using control channels (B J/Ψ K). ACP(Kππ) = 0.034 ± 0.012 ACP(KKK) = - 0.046 ± 0.012 ACP(πππ) = 0.120 ± 0.028 ACP(πKK) = - 0.153 ± 0.050

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UFRJ20Kazu Akiba

Bhhh DalitzStudy of CPV across Dalitz

plot (ACP vs m2hh):

large CPV in specific resonance areas

Typically at low m2 . More experimental work needed as well as on theory side

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UFRJ21Kazu Akiba

Not only Beauty: Charm physics

More than just beauty in LHCb since the beginning!Production cross section of charm at the LHC energy

is very high. Indeed it’s kind of a background for the B trigger Charm trigger is limited by the trigger selection and bandwidth.

Small CP violation in the charm sector: any significant observation could be a sign for “new physics”.

Asymmetries in D0 decays seem to be a good place to look for it

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UFRJ22Kazu Akiba

Time integrated ACP

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*To first order

*

A more robust measurement is given by

For a CP eigenstate final state (K-K+ or π+π-): pp collisions

UFRJ23Kazu Akiba

ΔACP measurement

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3.5 σ away from zero First evidence of CPV in the charm

sector

BUT: many other places to confirm it:

D+hhh, D0->hhhh, Ds , …

UFRJ24Kazu Akiba

Brief reminder of mixingTime Evolution of Schödinger’s equation:

Mass eigenstates can have different masses and decay widths than flavour states. Pure sample becomes mixed…

If CP is conserved, q/p = 1, and q and p are real (no phase)

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UFRJ25Kazu Akiba

Charm MixingMixing in D0 should be very small in SM and therefore could be a

probe for NP… Small contributions from box diagrams b loop CKM suppressed (|VubV*

cb|2≪1) s, d loops GIM suppressed ( (m2

s-m2d)/m2

W~0) Long-distance effects important (and difficult to calculate)

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Very slow…

UFRJ26Kazu Akiba

Measuring mixing in charm

Start with a D*+D0π+ tagged sampleFit first clean RS sample and determine signal

shape Then fit WS sample with the signal shape fixed by

RS sample Calculate WS/RS ratio R, fit the ratio of yields vs

decay timeflat? no mixingnot flat? mixing

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Tagged samples

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UFRJ28Kazu Akiba

Results

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x = Δm/Γ, y=ΔΓ/2Γ ; x’ = x cos δ + y sin δy' = y cos δ − x sin δ

No-mixing Hypothesis excluded at 9.1σarXiv:1211.1230

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Results

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No-mixing Hypothesis excluded at 9.1σarXiv:1211.1230

x = Δm/Γ, y=ΔΓ/2Γ ; x’ = x cos δ + y sin δy' = y cos δ − x sin δ

UFRJ30Kazu Akiba

Mixing in BsJ/ψφ : ϕsϕs is the CP violating phase difference between

oscillated and non-oscillated B0s decays.

In the SM ϕs is equal to 2βs = 2arg(-VtsV*tb/VcsV*

cb).

ϕsexpected

= 0.036 ± 0.002 rad

“New Physics” contributions to the box diagram could contribute a different value of ϕs …

With this channel ΔΓs and Γs

can be extracted from the Multi dimensional fit

A good sample of BsJ/ψφSILAFAE 12.12.12

2011 data

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Angular analysisBsJ/ψφ is a mixture of CP-even and odd final states

(V V) Need an angular analysis to disentangle, but that also provides

all the information we need.We also need a good proper time resolutionAnd B tagging…

Kazu Akiba SILAFAE 12.12.12

J/ψ rest frame Φ rest frame

2011 data

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Results BsJ/ψφ (LHCb-CONF-2012-002)

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Results BsJ/ψφ

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New delta gamma from atlas

UFRJ34Kazu Akiba

Proton-IonSept 13th – pA run (also) in LHCb ~4 hour data taking at L ~

5 1025 cm-2s-1

Very good and stable conditionsNo problem of multiplicities in the detectorUse of the System for Measuring Overlap with GasKS ,Λ, , f D peaks reconstructed offlineGood expectations for January (pA, Ap) run

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UFRJ35Kazu Akiba

Proton-Ion

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h

Sept 13th – pA run (also) in LHCb ~4 hour data taking at L ~ 5 1025 cm-2s-1

Very good and stable conditionsNo problem of multiplicities in the detectorUse of the System for Measuring Overlap with GasKS ,Λ, , f D peaks reconstructed offlineGood expectations for January (pA, Ap) run

UFRJ36Kazu Akiba

Proton-Ion

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Sept 13th – pA run (also) in LHCb ~4 hour data taking at L ~ 5 1025 cm-2s-1

Very good and stable conditionsNo problem of multiplicities in the detectorUse od the System for Measuring Overlap with GasKS ,Λ, , f D peaks reconstructed offlineGood expectations for January (pA, Ap) run

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Ks , L PRELIMINARY

l

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R =1.745 ± 0.014(stat)

R =1.818 ± 0.043(stat)

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f, D0 PRELIMINARY

l

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R =2.163 ± 0.071(stat)

R =1.820± 0.307 (stat)

UFRJ39Kazu Akiba

Upgrade

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UFRJ40Kazu Akiba

Motivation

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Currently LHCb design can cope with Lumi./bunch L > 4Ldesign LHC still provides more than what we can handle:

Current detector is limited due to 1 MHz readout. Higher Luminosities do not translate to higher yields for hadronic modes.

The upgrade is planned as a major Trigger/Readout upgrade: From 1 to 40 MHz full readout Every collision read out to a computing farm Higher instantaneous Luminosity Higher occupancies Full tracking in the trigger

ATLAS/CMS

LHCb Plan to go to20 x 1032 cm-2s-1

UFRJ41Kazu Akiba

In Fact

2

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UFRJ42Kazu Akiba

Detector Upgrade

VELO

Si Strips

(replace all)

Muon

MW

PC(almost

compatible)

Calo PMTs

(Reduce PMTs

gain+ replace R/O)

RICH HPDs(replace HPDs

+ R/O)

Silicon Trackers Si Strips (replace all)

Outer Trackers Straw tubes(replace R/O)

Option: Scint. Fibres

Design a common Read Out Board : Tell 40. SILAFAE 12.12.12

UFRJ43Kazu Akiba

Schedule

March 2011, “Letter of Intent for the LHCb Upgrade” submitted to LHCC

June 2011, LHCC endorses the LOI, green light for TDR preparation

June 2012, Submission of “Framework TDR for the LHCb Upgrade” to LHCC, endorsed in September/2012.

2013, R&D, technological choices, preparation of subsystems TDRs

Mid/end 2013, Submission of LHCb subsystems TDRs to LHCC

2014-2015, R&D of the choices and production of new detectors/ test of 40MHz prototypes.

2017-2018 Long Shutd. 2 / LHCb upgrade installation

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UFRJ44Kazu Akiba

ConclusionsThe LHCb has an outstanding performance!

Just a few of the achievements of the experiment. Mostly with 2011 dataset: 1/fb . Now:>3/fb!

First evidence of Bsμμ. First measurements of the CKM γ phase. Observation of very

suppressed channels Large CP asymmetry in B3 h; More analysis & theory needed! First evidence found CPV in D0 decays LHCb observed D0 mixing. No mixing excluded with 9.1σ. ϕs= -0.001 ±0.101(stat)±0.027(sys) ; no indications of NP. Nice data taking and analysis capability and in the pA run.

The results from the current experiment motivate for a complete Upgrade of the detector All the front end to be upgraded. Vertex/Tracking improvement. R&D effort coordinated up until 2016, installation in 2017.SILAFAE 12.12.12

UFRJ45Kazu Akiba

The LHCb Detector and Collaboration

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Thanks!

UFRJ46Kazu Akiba

Rare Decays summary

D0 μ+μ- BR < 1.3 x 10-8 new world best limit

K0S μ+μ- BR < 11 x 10-9 new world

best limitB0

(s) μ+μ-μ+μ- BR < 1.3 (5.4)x10-8 first limits

B0 μ+μ- BR < 9.4x10-10 new world best limit

B0s μ+μ- BR = (3.2+1.5

-1.2)x10-9 first evidence!

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UFRJ47Kazu Akiba

Bdμ+μ-

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BR(B0→ μ+μ-) < 9.4 x 10-10 @95% CL

UFRJ48Kazu Akiba

Long awaited measurement:Still 1/fb to be analysed!

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Bs μ+μ-

UFRJ49Kazu Akiba

Combination of AΓ and ΔACP

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Mod. Phys. Lett. A, Vol. 27, No. 26 (2012) 1230026

CL for no CPV : 2x10-5

• Plenty of theoretical papers since the evidence for ΔACP≠0 • Values of the order of 10-2 seem possible due to enhanced penguin

amplitudes• Still , no clear picture on whether SM (enhanced penguins) or NP more

measurements

UFRJ50Kazu Akiba

Physics of the Future

;

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UFRJ51Kazu Akiba

Time dependent γ with BsDsK

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UFRJ52Kazu Akiba

Few examples

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Carbon

fibre

-sensor

R-side circuit

-sidecircuit

R-sensor

UFRJ53Kazu Akiba

UPGRADE

Trigger upgrade

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20 kHz

HLTTracking and vertexingImpact Parameter cuts

Inclusive/Exclusive selections

Optional LLTLow Level Trigger

throttle1-40 MHz

40 MHz

To storage