Giovanni Carboni Università degli studi di Roma “Tor Vergata” and INFN

G. Carboni Spin 2012 Praha – Status of LHCb 1

Giovanni Carboni

Università degli studi di Roma “Tor Vergata” and INFN

On behalf of the LHCb Collaboration

Status of LHCb and recent results

2/7/20102

Symmetries and SpinPraha 2012

Charles University

22/7/20102

Outline of this talk

• Introduction• Detector performances• Selected physics results

• New states & decays• CP violation in b and c sectors• Rare decays• Electroweak

• Summary and outlook

Other LHCb Talks P. Naik Amplitude analysis for CP violation studies in LHCb I. Machikhiliyan Production and polarisation measurements in LHCb M. Ferro-Luzzi LHCb upgrade A. Shires Rare decays in LHCb

G. Carboni Spin 2012 Praha – Status of LHCb

The LHCb experiment

Aspen 2012 – Stefano de Capua New results from LHCb 3/17

G. Carboni Spin 2012 Praha – Status of LHCb 42/7/20102

> 800 members59 institutes16 countries


ComplementarityIn the search for New Physics Beyond the Standard Model the LHCb approach is complementary to the direct one of ATLAS and CMS If NP exists at the TeV scale its effects could be observed in decaysand CP asymmetries at much lower energies

This requires several high-precision tests of the SM and of the CKM framework we use to describe CP violation

• chart the known territory more accurately • explore new regions

Standard Model

t

s

s

Bs decay: “Penguin” diagram

W

W

W

b

B s

0

t

t

Bs–Bs oscillations: “Box” diagram

–

msSM |Vts

2|,s

SM = –arg(Vts2) = 2s

s

b

Bs0

s

s

s

b

Bs0

s

Strengths of indirect approach

Can access higher scales and therefore see effect earlier:— K0 mixing and decay hints to c-quark prediction (GIM, 1973)— Third quark family inferred by Kobayashi and Maskawa (1973) to explain

small CP violation measured in kaon mixing (1964), but only directly observed in 1977 (b) and 1995 (t)

— Neutral currents (+N +N) discovered in 1973, but real Z discovered in 1983

— B0 mixing (1987) hints to large t-quaks mass Can access the phases of the new couplings:

— NP at TeV scale must have a “flavor structure” to provide the suppression mechanism for already observed FCNC processes once NP is discovered, it is important to measure this structure (including new phases)

New Physics

? ???

ms s

? ?

2/7/20102 6G. Carboni Spin 2012 Praha – Status of LHCb


The LHCb Experiment

The LHCb Forward spectrometer layout efficiently exploits the large production cross-section for b-anti b pairs in the forward direction (2 < h < 5) at moderate PT

b 3.11.5 41)( uBTeV7@ s

within acceptancedoi:10.1007/JHEP04(2012)093 unprecedented number

of reconstructable b-hadronscreated per year

democratic production:mesons, baryons, charmedparticles


Detector highlights• Excellent Impact Parameter (IP) and Vertex Resolution

• Si Vertex Locator (VELO) inside LHC beam pipe (8 mm from beam)

• Superior mass resolution • dipolar magnetic field (4 Tm)• high spatial accuracy of tracking• precise spatial alignment

• Particle identification• hadrons• muons • electrons

• powerful trigger• highly configurable• large rejection power


The LHCb Detector

Forward Spectrometer

• Angular acceptance :15<θ<300 mrad

• Nominal luminosity:L = 4 x 1032cm-2s-1

(design 2 x 1032cm-2s-1)

Ds

Bs K

K

K

d≈1 cm

47 m 4 mPrimary vertex

Example

2/7/20102


• Silicon strip detector• 21 stations • Each station measures R and

Phi• Left-Right staggered in Z to

allow for overlapRetractable by ± 2.9 cm during injection

p

p

-sensors r-sensors

• 10o-20o stereo angle• Inner and outer region• 2048 strips• Pitch: 35 to 100 µm

• 4x45o sectors• 2048 strips• Pitch: 40 to 100 µm

42 mm

8 mm

3578

39

97 umpitch

~1m

Vertexing in the VELO

2/7/20102

[CO

NF-2012-002]

Prompt J/y Bs J/y

Impact parameter resolution ~ 20 mProper-time resolution: t = 45 fscf CDF: t = 87 fs [PRL 97 242003] [PRL 97 242003]


Tracking SystemSilicon + Straw TubesTT + 3 stations (T1,T2,T3) each with 4 stereo planes (0o,+5o,-5o,0o)

OT

T1T2

T3

TT

IT

Inner Tracker~0.5 m2 around beam pipe (130k ch)

Trigger Tracker~1.41.2 m2

(144k ch)

TT: 128 Modules(7 Si sensors)

IT: ladders with 1 or 2 sensors

Similar sensors for TT & IT:Si µ-strip with pitch ~ 200 µm

Outer TrackerStraw Tubes(56 k ch)Pitch 5.25 mmLength 2.4 ~ 4.9 m

dp/p = 0.4-0.6 %


Excellent resolution + calibration of the mass scale

(dp/p)scale = 0.02 %

t> 0.3 ps

PLB 708 (2012) 241

σm = 9.0 ± 0.6 MeV/c2 σm = 7.0 ± 0.3 MeV/c2

Bs J/ψ φΛb J/ψ Λ


ECAL: Shashlik Pb-scintillator (E)/E = 10% /√E 1%HCAL: Tile Fe-scintillator allows triggering on hadronic final statesMuon system: 5 stations MWPCs+3-GEM Fe filters

Bs→ g

Preshower

Lead and SPD

HCAL ECAL

MUON570

candidates

y(2S)and X(3872) →

Calorimeter and Muon Detectors

EPJC (2012) 72:1972

RICH2

23/08/2010G. Carboni HCP 2010 Toronto – Status of LHCb 14

Unique to LHCb: 2 RICH Detectors – 3 Radiators

RICH1196 HPDRICH2

288 HPD

HPD Readout83 mm 1024 Pixels

New this year: gas-tight box for aerogelto avoid contamination by C4F10 gas

2 < p < 100 GeV/ccoverage


The LHCb Trigger

4.5 kHz

L0 e, g

40 MHz

1 MHz

L0 had

L0

ECALAlley

Had.Alley

Global reconstruction

30 kHz

MuonAlley

Inclusive selections:topological, ,

+track, ,D→X, ΦExclusive selections

Level-0

HLT1

HLT2

‘High-pt’ signals in calorimeter & muonsystems

Associate L0 signals withtracks, especially thosein VELO displaced from PV

Full detector information available.Global reconstruction similar tooffline (nclusive and exclusive).

2/7/20102

Triggering is a challenge! ~1/100 events contain

b interesting b branching

fractions ~10-3 or less

storage

Farm with 19000 CPUcoresHLT efficiency> 80%

Overall typical L0xHLT efficiency:30% (multibody hadron decays) to 90% (dimuons)

O(1010)events/y


Data taking in 2012 running conditions: L = 4 1032 cm-2 s-1

L0 trigger 1 MHz saturating the bandwidth deferred HLT trigger (10% gain) magnet polarity regularly reversed (systematics!) tilted beam-crossing plane (systematics!)



Periodical magnetic field reversal crucial to keep systematic asymmetries under control

PLB 713 (2012) 186

)%10.022.033.0( PAasymmetry production ss DD


Flavor tagging

Important for oscillations and CP violation measurements

same side, uses or K emitted together with signal b-hadron

opposite side, detects flavor of partner b-hadron from decay

ϵeff =ϵtag(1-2ω)2=ϵtag D2


Example: Same-Side K vs. Opposite Side tagging in B0s D-

s

SSK only ϵeff =(1.3±0.4)% OS only ϵeff =(3.2±0.8)%

Calibration performed using several self-tagging control channels EPJC (2012) 72:2022

LHCB

-CON

F-20

11-0

50


2012

1.5 fb-1 goal for 2012

Integrated L in 2011 @ 7 TeV, 2012 @ 8 TeV

Excellent data taking performance

In 2012 larger physics

yield expected

(8 TeV vs. 7 TeV)


LHC performanceLong fills with ~ 50 % time in stable beam.

• Thursday only bad day.

• Monday game over at 1pm: 90 m run/MD starting

New filling scheme from Fill 2734 on Friday (lost some bunches)

ATLAS, CMS, LHCb Luminosities

Automatic luminosity leveling

stable beams VELO close: 4 min stable beams L = 4 1032 cm-2 s-1: 7 min

Example week 24this year


Physics results

Impossible to list all measurements

I will try to give a panoramic view, with emphasis on the capabilities of the experiment

For more details on quarkonia, CP violationin Bs and rare decays refer to dedicated talks.

58 physics publications to date, more in pipeline> 80 preliminary results submitted as Conference Papers


Best measurements of B0s and Λ0

b masses

PDG

PLB 708 (2012) 241

Precision measurements


Penguins

ss KJB y/0

important to evaluate the penguincontribution to the measurementof sin2 in B0 J/ψ Ks from future CPV measurement in B0

s J/ψ Ks

Most precise determination of the B0s J/ψ Ks branching fraction

In agreement with SU(3) expectations

0.42 fb-1

arXiv:1205:0934PLB (2012) in press


Some firsts

test of QCD predictions

PRL 108, 251802 (2012)

0.8 fb-1


Two new excited b-baryons

Ʌb*0 Ʌb

0

Ʌb0 Ʌc

predicted by quark modelJP = 1/2- , 3/2-

4.9 σ 10.1 σarXiv:1205.3452

Talk by I. Machikhiliyan


Never seen before. B+ K++ (4.8 ± 0.4) 10-7 PDG

BELLE limit B < 6.9 10-8 (90% CL) with 8 108 B-antiB pairsSM prediction (1.96 ± 0.21) 10-8 (*)1.0 fb-1 usedAnalysis uses Boosted Decision Tree (BDT)

kinematics, vertex quality, track quality trained on simulated signal sample and bkgd from data PID selection applied separately vetos on B+ J/ψ (ψ(2S)) K+

(*) H.-Z.Song et al., Comm. Th. Phys. 50 (2008)

More penguins


• Use B+→ J/ψ K+ events to define signal shape and, under π+μ+μ- hypothesis, shape of mis-identified events• Components for partial reconstructed B decays and combinatorial bkgd• Validate by separating B+→J/ψK+ and B+→J/ψπ+ decays

Fitting

5.2events 3.25 7.6

4.6

Preliminary: B (B+ ++-)= (2.4±0.6(stat)±0.2(syst)) 10-

8

LHCb-CONF-2012-006

dbFirst

transitionever observed


still penguins: B0 K0*+–

Interference of the two diagramsPossible NP contributions

crossing measured 1st time 421.1

3.120 /GeV 9.4 cq

earlier hints at possible discrepancies not confirmed consistent with SM prediction

900 events @1 fb-1:larger than previousworld total!

LHCb-CONF-2012-008

Talk by A. Shires

PRELIMINARY


I’VE NEVER SEEN A FEYNMAN DIAGRAM THAT LOOKS LIKE

YOU!

WHY THE HELL YOU CALL THEM PENGUIN

DIAGRAMS? THEY DON’T LOOK LIKE

PENGUINS


Double charm production Higher order QCD

process?

Intrinsic charm?

Double Parton Scattering?

J/ψ pairs previously seen in NA3 (FT) in 1982

Talk by I. Machikhiliyan

A. Szczurek arXiv:1206.0274

33

• Standard simple selection of single J/y candidates in the +- decay mode.

• Background from 2 J/y produced in different pile-up collisions or in the decay of a B hadron removed requiring the 2 J/y come from a common vertex.

nb 1.10.11.5// yy JJ

Theoretical expectations in LHCb acceptance

LO CSM with Single Parton Scattering (including feeddown from y(2S)): 4.1 ± 1.2 nb. [A. V. Berezhnoy et al., Phys. Rev. D84 (2011) 094023]

Contribution from Double Parton scattering: 2 ± 1 nb [A. Novoselov, arXiv:1106.2184]

J/ψ pairs

PLB 707 (2012) 52

arXiv:1205.0975

34

• Combine hadron, with vertex requirement to remove contamination from pile-up and B hadron decays.

J/yD0 J/yD+

J/yDs+

J/yLc+

J/ψ + open charmopen charm pairs

D0 D0 D0 D+

D0 Ds+ D0 Lc

+

arXiv:1205.0975


CP Violation


First evidence (3.3) of CP violation in Bs

0080080270sum/)]()([ 00...KBKBA ssCP

PRL 108, 201601 (2012)

008001100880sum/)]()([ 00...KBKBACP

Most precise single measurement

byproduct

0

sB 0sBBs → K Bs → K


CP violation in Bs mixing

Small SM phase, good place to look for NP effects

Phys. Rev. D84 (2011) 033005,

More in talk by P. Naik

0016.00015.0*

*

0363.0arg22

cbcs

tbtsDM

SMs VV

VV


PRL 108, 101803 (2012)

Two-fold ambiguity ΔΓs -ΔΓs resolved by measuring ΔΓs

0.37 fb-1

8500 candidates


Latest combined measurements of

Preliminary combined result using 1 fb-1

ϕs = -0.002 ± 0.083 ± 0.027 rad

LHCb-CONF-2012-002

still statistics dominatedroom for improvement

Details in Talk by P. Naik

arXiv:1204.5675 ϕs from Bs J/ψ φ 21200 evs. ϕs from Bs J/ψ f0(980) and J/ψ f0(1370) 7400 evs ΔΓs = ΓL-ΓH = 0.116 ± 0.018 ± 0.006 ps-1

CDF finds consistent result with11000 decays

(CDF Note 10778)


Towards the g measurement

KKD ,0 CP mode

ADS mode

5.8 σ CP asymmetry observed 1 fb-1

KD 0 KD 0

PLB 712, (2012), 203

More in Talk by P. Naik

B+ [+K-]DK+B- [-K+]DK-

B- [-K+]Dπ- B+ [+K-]Dπ+

[Phys. Rev. D, 63 (2001), p. 036005]


D0 mixing now established at % level

CP Violation expected to be small in SM since relevantdiagrams are dominated by the two first generations

Indirect CP Violation (in mixing) expected to be universal and of O(10-4)

Direct CPV expected to be negligible in Cabibbo-

allowed decays

up to O(10-3) in Single-Cabibbo-suppressed decays

CP in charm sector

LHCb-PAPER-2012-006


Huge statistics available

)()()()()( *raw

DAAfAfAfA PsDDCP

Detector and production asymmetries cancel in the difference)()( rawraw

AKKAACP

use s charge to tag D0/D0

or KKf


Lots of recent theory papers on the subject motivated by the ACP measurement.

However new calculations suggest that large hadronic enhancements in the SM could account for the result (e.g J. Brod et al., arXiv:1111.5000).

Stay tuned for more data…

0.62 fb-1zero CPV excludedat 3.5 σ level

ΔaCPdir = (−0.656 ± 0.154 )%

PRL 108, 111602 (2012)

world average result

442/7/20102G. Carboni Spin 2012 Praha – Status of LHCb

Bs +–

• Bs strongly suppressed in SMPredicted BR = (3.2 ± 0.2) 109 *

very sensitive to new physics• Analysis based on multivariate estimator

(BDT, combining vertex and geometrical information) & dimuon mass M

At the moment not enough candidates to provide significant measurement of BR

• World-best limit set:BR < 4.5 × 10-9 (at 95% CL)cf < 7.7 × 10-9 (CMS arXiv:1203.3976) < 22 × 10-9 (ATLAS CONF-2012-010)

• Large enhancement of BR relative to SM expectation is ruled out

PRL 108, 231801 (2012)

Talk by A. Shires

(arXiv:1005.5310)


• LHCb results provide strong constraints on possible models for new physicsComplementary to the direct searches at ATLAS/CMS

• Recent examples: limit on Bs constraining SUSY at high tan and combination of Bs and s restricting various models: [D. Straub, arXiv:1107.0266[N. Mahmoudi, Moriond QCD]

(s)

Direct exclusion(CMS 4.4 fb-1)

B s

(LHCb 1 fb-

1 )

Impact of LHCb measurements

2/7/20102


W & Z


2.7 TeV/c Z0: probably the fastest ever made (by man)


W and Z physics in the forward region has unique characteristics

one parton at high, one at low Bjorken-x

LHCb uniquely probes PDF down to x ~ 810-6

Q2 defined by +- mass


Z μ+μ-

37 pb-1arXiv:1204.620accepted by JHEP

W μ ν


Cross-section measurements

LHCb-CONF-2012-011


LHCb-PAPER-2012-008


Z + jet production

LHCb-CONF-2012-016


ConclusionsLHCb is in great shape

The detector is more than 99% operational and routinely working at x2 its design luminosity

• today more than 1.6 fb-1 on disk– Improved on Tevatron and B-factories

spectroscopy, masses, lifetimes– Several world-best meaurements

s, ms, Bs → μμ, s etc.– Settled the Bs→J/ψϕ, Bd→K*μμ anomalies– CPV established in charm– Not only CP and rare ecays: also EW, quarkonia, exotic states

• strong constraints on NP in the flavor sector• possible hints of NP require further study (2012 and

beyond)

Upgrade in preparation for 2018: 10x yields, software trigger talk by Max Ferro-Luzzi


...stay tuned!

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Giovanni Carboni Università degli studi di Roma “Tor Vergata” and INFN