FAE06, Caracas, Dec 11 th 2006 Physics with first data in ATLAS at the LHC – F. Derue (LPNHE...

FAE06, Caracas, Dec 11th 2006 Physics with first data in ATLAS at the LHC – F. Derue (LPNHE Paris) 1

Physics with first data in ATLAS at the LHC

1. Status of the LHC2. The ATLAS detector3. Towards physics4. Physics with first data5. Conclusion

Frédéric Derue Laboratoire de Physique Nucléaire et de Hautes Energies de Paris,

IN2P3-CNRS et Université Pierre et Marie Curie-Paris6 et Université Denis Diderot-Paris7

Reunión de Física de Altas Energias, FAE06

11-13 de Diciembre de 2006 Caracas


LHC • pp s = 14 TeV Ldesign = 1034 cm-2 s-1 (after 2009)

Linitial few x 1033 cm-2 s-1 (until 2009)

• Heavy ions (e.g. Pb-Pb at s ~ 1000 TeV)

TOTEM

ALICE : ion-ion,p-ion

ALICE : ion-ion,p-ion

ATLAS and CMS :general purpose

ATLAS and CMS :general purpose

27 km LEP ring 1232 superconducting dipoles B=8.3 T

TOTEM (integrated with CMS):pp, cross-section, diffractive physics

TOTEM (integrated with CMS):pp, cross-section, diffractive physics

LHCb : pp, B-physics, CP-violationLHCb : pp, B-physics, CP-violation

The Large Hadron Collider at CERN


Status of the machine and schedule

Revised LHC schedule (cf. CERN council on 23 June 2006) last magnet installed : March 2007 machine and experiments closed : 31 August 2007 first collisions (s=900 GeV, L~1029 cm-2 s-1) : November 2007

commissioning run at injection energy until end 2007, then shutdown (3 months ?) first collisions at s=14 TeV (followed by first physics run) : spring 2008

goal: deliver integrated luminosity of few fb-1 by end 2008LHC commissioning

sectors 7-8 and 8-1 will be fully commissioned up to 7 TeV in 2006-2007 If other sectors are commissioned up to 7 TeV no beam will circulate in 2007 the other sectors will be commissioned up to the field needed for de-Gaussing initial operation will be at 900 GeV (CM) with a static machine (no ramp, no squeeze)

to debug machine and detectors full commissioning up to 7 TeV will be done in the winter 2008 shutdown


The ATLAS collaboration

(As of the September 2006)

35 Countries 161 Institutions 1830 Scientific Authors total(1470 with a PhD, for M&O share)

Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, Bologna, Bonn, Boston, Brandeis, Bratislava/SAS Kosice, Brookhaven NL, Buenos Aires, Bucharest, Cambridge, Carleton, Casablanca/Rabat, CERN, Chinese

Cluster, Chicago, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, DESY, Dortmund, TU Dresden, JINR Dubna, Duke, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, LPSC Grenoble, Technion Haifa, Hampton,Harvard, Heidelberg, Hiroshima, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici, KEK, Kobe, Kyoto,

Kyoto UE,Lancaster, UN La Plata, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Manchester, Mannheim, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU,

MPI Munich, Nagasaki IAS, Naples, New Mexico, New York, Nijmegen, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Ritsumeikan, UFRJ Rio de Janeiro, Rochester, Rome I, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, Southern Methodist Dallas, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv,

Thessaloniki, Tokyo ICEPP, Tokyo MU, Toronto, TRIUMF, Tsukuba, Tufts, Udine, Uppsala, Urbana UI, Valencia, UBC Vancouver, Victoria, Washington, Weizmann Rehovot, Wisconsin, Wuppertal, Yale, Yerevan


How huge is ATLAS ?

Size of collaborationSize of collaboration

35 countries 161 institutions 1830 scientific authors (1470 with PhD for M&O share)

Size of detectorsSize of detectors

volume : 20 000 m3

weight : 7000 tons ~80 million pixel readout channels near vertex 175 000 readout channels for the liquid argon electromagnetic calorimeter 1 million channels and 10 000 m2 area of muon chambers very selective trigger/DAQ system (online rate reduction > 105) large scale offline software and worldwide computing (GRID) share)

Time scale will have been about 25 years from first conceptual studies Time scale will have been about 25 years from first conceptual studies (Lausanne 1984) to solid physics results confirming that LHC will have (Lausanne 1984) to solid physics results confirming that LHC will have taken over the high-energy frontier from Tevatron (Chicago) (early 2009 ?) taken over the high-energy frontier from Tevatron (Chicago) (early 2009 ?)

ATLAS superimposed tothe 5 floors of building 40 in CERN


The ATLAS detector The ATLAS detector

Tracking system (||<2.5, B=2T):-- Si pixels and strips-- Transition radiation Detector (e/ separation)

Calorimeters (||<5) : -- EM : Pb-LAr with accordion shape -- HAD: Fe/scintillator (central), Cu/W-LAr (fwd)


Muon spectrometer (||<2.7) : air-core toroids with muon chambers

Length : ~ 46 m

Diametre : ~ 25 m

Weight : ~ 7000 tons

~108 electronic channels

~3000 km of cables

Cost : ~ 340 M€ / 10 y

1800physicists

x

y

z

2

tanln Transverse plane projected physical quantities are measured: - pT - ET, ET

miss


Calorimeters (||<5) : -- EM : Pb-LAr with accordion shape -- HAD: Fe/scintillator (central), Cu/W-LAr (fwd)

Muon spectrometer (||<2.7) : air-core toroids with muon chambers


Length = 55 mWidth = 32 mHeight = 35 mDeep = 90 m

The underground cavern at pit-1 for the ATLAS detector

(Across the street from the CERN main entrance)


Detectors must survive for ten years or so of operationDetectors must survive for ten years or so of operation

Radiation damage to materials and electronics componentRadiation damage to materials and electronics component

Problem pervades whole experimental area (neutrons) : Problem pervades whole experimental area (neutrons) : NEW !NEW !

Detectors must provide precise timing and be as fast as feasibleDetectors must provide precise timing and be as fast as feasible

25 ns is the time interval to consider : 25 ns is the time interval to consider : NEW !NEW !

Detectors must have excellent spatial granularityDetectors must have excellent spatial granularity

Need to minimise pile-up effects : Need to minimise pile-up effects : NEW !NEW !

Detectors must identify extremely rare events, mostly in real timeDetectors must identify extremely rare events, mostly in real time

Lepton identification above huge QCD background (e.g electron/jet ratio Lepton identification above huge QCD background (e.g electron/jet ratio at the LHC is ~10at the LHC is ~10-5-5, i.e factor 50 worse than at Tevatron), i.e factor 50 worse than at Tevatron)

Signal cross-sections as low as 10Signal cross-sections as low as 10-14-14 of total cross-section : of total cross-section : NEW !NEW !

Online rejection to be achieved is ~10Online rejection to be achieved is ~1077 : : NEW !NEW !

Store huge data volumes to disk/tape Store huge data volumes to disk/tape (~10(~1099 events of 1 Mbyte size per year) : events of 1 Mbyte size per year) : NEW !NEW !

Generic features required of ATLAS


Generic features required of ATLAS

Detectors must measure and identify according to certain specificitiesDetectors must measure and identify according to certain specificities

tracking and vertexing : ttH with Hbb electromagnetic calorimetry : H and HZZ eeee muon spectrometer HZZ missing transverse energy : supersymmetry

Detectors must pleaseDetectors must please

collaboration : physics optimisation, technology choices funding agencies : affordable cost (originally set to 475 MCHF per experiment) young physicist who will provide the main thrust to the scientific output

of the collaborations : how to minimise formal aspects ? How to recognise individual contributions ?


Tracking of charged particles : Tracking of charged particles : the Inner Detector

SCT

TRT

Three completed Pixel disks(one end-cap) with 6.6 M channels

The inner detector is organized into three sub-systemsThe inner detector is organized into three sub-systems

pixels (0.8108 channels) silicon tracker (SCT) 6106 channels transition radiation tracker (TRT) 4105 channels

Magnet systemMagnet system

solenoid integrated with the LAr cryostat 2T field with a stored energy of 38 MJ


Tracking of charged particles : reconstructionTracking of charged particles : reconstruction

Complex task for tracking and Vertexing because of pile-up.

Triggering algorithms have to be fast and robust to avoid to miss rare events

LLintint/y (fb/y (fb-1-1)) L (cmL (cm22/s)/s) s (TeV)s (TeV) Minimum Minimum bias/bco bias/bco

LHC ( low L) LHC ( low L) 1010 2x102x103333 1414 55

LHC (high L) LHC (high L) 100100 10103434 1414 2525

At high luminosity per bunch crossing (25 ns)At high luminosity per bunch crossing (25 ns)

more than 200 tracks about 15-20 vertex candidates


Electron/ : the electromagnetic calorimeter

The electromagnetic calorimeterThe electromagnetic calorimeter

EM barrel : (|n|<1.475) [Pb-LAr] EM end-caps : (1.4<|n|<3.2) [Pb-LAr] lead/Liquid argon sampling calorimeter

with accordion shape

E

Physics requirementsPhysics requirements discovery potential of Higgs (into or 4e)

determines most of the requirements largest possible acceptance (accordion) large dynamic range from 20 MeV to 2 TeV

energy resolution E/E~10%/E0.7% linearity ~0.1% (W-mass precision measurement) particle identification position and angular measurement : 50 mrad/E


Barrel/Encap LAr Calorimeter Installation

170 tons assembly

One end-cap calorimeter (LAr EM, LAr HAD, LAr Forward inside same cryostat,

surrounded by HAD Fe/Scintillator Tilecal) being moved inside the barrel toroid


The hadronic calorimeter and jet reconstruction

November 4th 2005: Calorimeter barrel after its move into thecenter of the ATLAS detector


Precision chambers:- MDTs in the barrel and end-caps- CSCs at large rapidity for the innermost end-cap stations

The Muon Spectrometer is instrumented with precision chambers and fast trigger chambers

Muon spectrometer

Trigger chambers:- RPCs in the barrel- TGCs in the end-caps

TGC big wheelToroidal field to bend muons


Trigger system

Level 1 trigger hardware trigger (2.5 s latency) calorimeter + muon chambers defines Regions Of Interest (ROI)

Level 2 processing in parallel info from ROI,

uses ID information (latency 10 ms)

Event Filter uses tools similar to “offline” code

thanks to longer latency ~1s

Challenge have tracking, b-tagging and time information

at trigger level speed !

40 MHz

75 kHz

~2 kHz

~ 200 Hz

25 ns is the time interval to consider !


The data treatment at the LHC

Needs for LHC experiments each event is independent of the others computing power ~100000 PC (P4 3 GHz, 2 GB ram) storage capacity for LHC experiments

20 petabytes/y on magnetic tape

1 petabyte/y on disc for the analysis possibility to access data from institutes production of Monte Carlo data necessary to the understanding

of results of the analysis (30 mn/event)

ATLAS computing model first publication mid-2005 (Technical Design Report),

first modifications in 2006, will have to adapt with first data grid part

use as much as possible standard LCG (LHC Computing Grid) tools

have to be fully operational (low error rate in production, error monitoring …)


2005 2006 2007 2008

1: Testbeams

2: Subdetector Installation, Cosmic Ray Commissioning

3: Single beam

4: First LHC collisions

5: First Physics

2.5: Spring ’07: Global cosmic run

Towards physics


Towards physics : test beams 2001-2002H6 & H8 beam lines at CERN

Beam chambers Si layers

Cerenkov counter

Studies presented : - transition radiation for e/ separation

Studies presented : - energy resolution, constant term - shower development - / separation

Calorimeter

TRT experimental setup

TRT prototypes , e and beam from 1-300 GeV

LArEM series modules

4 barrel and 3 end-cap production modules e and beam from 10-300 GeV


Towards physics : combined test beam 2004

G4 simulationof subdetectors

setup

TRTLArEM

Tile

90 millions events collected 4.6 Tbytes of data beams:

e±,± 1250 GeV±,±,p 350 GeV ~30 GeV

B from 01.4 T

Pixels + SCT

Muon

For the first time, all Atlas sub-detectors integrated and run together with: - « final » electronics- common DAQ- slow control - common Atlas software to analyse the data

First experience with : - Inner Detector alignment - ID/Calo alignment- ID/Calo track matching- ID/Calo combined reconstruction

beam

Full « vertical slice » of Atlas tested on CERN H8 beam line between May-November 2004


e/ separation using the TRT

Typical TR photon energy depositions in the TRT are 8-10 keV Pions deposit about 2 keV

Results from TB 2002 @20 GeV Results from CTB2004

@9 GeV

90% electron efficiency210-2 pion efficiency

Preliminary

Electron identification makes use of the large energy depositions due to the transition radiation (X-rays) when they traverse the radiators


Performance of the LArEM

Energy resolution

rms cL=0.37%E

nerg

y (G

eV)

Constant term

Performance of the LArEM similar in both test beamsand in agreement with what expected

Calo TB 2001-2002 CTB 2004 (preliminary)

Run 2102478Ebeam=180 GeV = 0.3

4.5‰P13 production module > 7 rms cL = 0.45 %

Ene

rgy

(GeV

) @245 GeV@245 GeV

10.00.1 % /E 0.210.03 %

(middle cell unit) (middle cell unit)

E/E ~0.83 %


Electromagnetic shower shapes

Longitudinal development Lateral development

Ebeam = 10 GeV Ebeam = 60 GeV

Ebeam = 100 GeV Ebeam = 180 GeV

Fraction of E

rec. in 3rd samp.

Fraction of E

rec. in 1st samp.

2rd samp.

presampler

The contamination and the non-uniform distribution of dead material located in the beam line and not described in the Monte Carlo might explain the small discrepancyShower profile in agreement between data/simulation from 10 to 180 GeV

LArEM beam test 2001-2002Comparison between data and G4 standalone simulation


/0 separation in full simulation and test beam

R (data) = 3.18 ± 0.12 (stat)R (MC) = 3.29 ± 0.10 (stat) = 90 %

--- Data --- G3 MC

R. Sacco (ATLAS Coll.) NIM A(550), 2005

Test beam 2002 @50 GeVG4 full simulation

R (G4) = 3.2 ± 0.2

Fraction of energy

outside shower core

E2nd max - Emin

00→→

The identification of photons is based on set of cuts applied on calorimeters information (no leakage in HCAL, narrow shower in EM2 Calorimeter). After application of HCAL + EM2 criteria, the remaining background is composed at ~80% of isolated 0’s produced by jet fragmentation

A /0 separation ~3 is needed for =90%. For this the fine granularity of the EM sampling 1 is used


Towards physics : -conversionsATLAS preliminary

ATLAS @ LHC: -conversion probability in tracker is > 30% important to develop (and validate !) efficient reconstruction tools

Converted photon

Primary electron

Run 2102857 event # 88

tr

ack

Inner Detector tracks extrapolated to ECAL and compared to calo clusters

cluster

primary electron

converted


Shown in this picture is the end-cap set-up, it is preceded in the beam line by a barrel sector

Towards physics : -system

The large-scale system test facility for alignment, mechanical, and many other system aspects, with sample series chamber station in the SPS H8 beam

Example of tracking the sagitta measurements, following the day-night variation due to thermalvariations of chamber and structures, and two forced displacements of the middle chamber


Towards physics : cosmic rays runs

First cosmics rays registered in the underground cavern barrel muon chambers (MDT and RPC)

and level-1 trigger

In December 2005 in MDTs

and in June 2006 in RPCs


Towards physics : cosmic rays runs

Cosmic rays runs event display in the barrel TRT and in the SCT

End of February 2006 the barrel SCT was inserted into the barrel TRT, and this component will be ready for the final installation in ATLAS in August 2006 after further commissioning at the surface with cosmics

Integrations of the two end-caps (SCT and TRT) are ongoing for installation end of 2006


Towards physics : cosmic rays runsCosmic rays runs

event display from the first LAr+Tile calorimeter barrel cosmic run

The barrel LAr and scintillator tile calorimeters have been since January 2005 in the cavern in their ‘garage position’ (on one side, below the installation shaft)


Towards physics : beam-halo events

From April-May 2007 ? Only one beam in the machine : here physics data are beam-halo and beam-gas events


Towards physics : beam-gas events

Collisions are essentially minimum bias 23 m : ~1.2105/s (integrated : 21011) 3 m : ~1.5104/s (21010; ID size) 20 cm : ~1103/s (2109; ID soft acceptance)

Particles : consider 3 m and ask pT>1 GeV : ~1.5109 over two months : ~5.5108 of one beam operation spectrum is soft : few Hz of electromagnetic clusters with ET>2 GeV

trigger is an issue


What samples in 2007 ?

ATLAS preliminarys =900 GeV, L = 1029 cm-2 s-1

Jets pT > 15 GeV

Jets pT > 50 GeV

Jets pT > 70 GeV

W e,

Z ee,

J/

100 nb-130 nb-1

+ 1 million minimum-bias/day

(b-jets: ~1.5%)

First collisions (s = 900 GeV, L~1029 cm-2 s-1) : November 2007 commisioning run at injection energy until end 2007 30% data taking efficiency included (machine+detector) + trigger and analysis efficiencies

start to commission triggers and detectors with collision data (min. bias, jets…) in real LHC environment may be first physics measurements (min. bias, underlying events, QCD jets..) ? observe a few Wl, , J/


First physics run in 2008

prepare the road to discovery …… it will take time …

First physics run (s = 1400 GeV, L~1032 cm-2 s-1) : spring 2008 1 fb-1 (100 pb-1) 6 months (few days) at L=1032 cm-2 s-1

with 50% data taking may collect a few fb-1 per experiment by end 2008

With these data understand and calibrate detectors in situ using well-known physics samples

Zee, tracker, ECAL, muon chambers calibration and alignment, etc.

tt bl bjj jet energy scale from W jj, b-tagging performance, etc.• measure SM physics at s = 14 TeV : W, Z, tt, QCD jets… (also because omnipresent backgrounds to New Physics)

55101088

830830

1.51.5101033

33101044

(pb)(pb)

109 Belle/BaBar 1013106bb

104 Tevatron1071tt

107 LEP1071.5Zee

104 LEP / 107 FNAL10830W l

Total collected before start of LHCN/yearN/sProcess


tt 250 pb for tt bW bW bl bjj

Isolated lepton pT> 20 GeV

ETmiss > 20 GeV

4 jets pT> 40 GeV

NO b-tag !!

2 jets M(jj) ~ M(W)

ATLAS preliminary

50 pb-1

W.Verkerke

W+n jets (Alpgen) +

combinatorial background

3 jets with largest ∑ pT

Top physics in 2008

Example of initial measurement: understanding detector and physics with top events

can we observe an early top signal with limited detector performance ?

in addition, excellent sample to : commission b-tagging, set jet energy scale using W jj peak understand detector performance for e, m, jets, b-jets, missing ET, …

understand / constrain theory and MC generators using e.g pT spectra


Luminosity/expt (fb-1)100 pb-1

M (TeV)

ATLAS + CMS

1 10 100

1

1.5

2.5

2

m (˜ q , ˜ g ) ~ 1 TeV

˜ q , ˜ g

01

Z

q

q

02

˜ g

˜ q

Example of “early” discovery : Supersymmetry ?

If SUSY at TeV scale could be found “quickly” … thanks to : large cross section ~10 events/day ar 1032 for spectacular signatures (many jets, leptons, missing ET)

Our field, and planning for future facilities, will benefit a lot from quick determination of scale of New Physics. e.g. with 100 (good) pb-1 LHC could say if SUSY accessible to a 1 TeV ILC

BUT: understanding ETmiss

spectrum (and tails from instru- mental effects) is one of the most crucial and difficult experimental issue for SUSY searches at hadron colliders


Run IIV. Shary CALOR04

ETmiss spectrum contaminated by cosmics,

beam-halo, machine/detector problems, etc.

Missing ET (GeV)

R: Z() +jetsB: as estimated from W()+jets

1 fb-1

ATLAS preliminary

I.Okawa et al.

S.AsaiJets + 1l +ETmiss

1 fb-1

Jets + ETmiss (0l) ATLAS preliminary

m (˜ q , ˜ g ) ~ 1 TeV

Meff (GeV) = ET (i)i=1,4

ETmiss

Estimate physics backgrounds using data (control samples)

no cleaningafter cleaning

Example of “early” discovery : Supersymmetry ?


SM Higgs boson with first data

Current indications are for a ‘light Higgs’ : search for Higgs in mass region 114<mH<200 GeV is crucial

*July 2006. Combination of CDF+D0 Run I+II results

mt = 171.4 1.2 (stat) 1.8 (syst) GeV

Signal cross section (including BR) can be as low as 10-14 the total cross section


back

gro

un

dsi

gn

al


H key ingredients : rare decay mode with BR~10-3 (2.186 10-3 for mH=120 GeV)

the signal should be visible as a small peak above the continuum background good energy resolution of

the electromagnetic calorimeter

Irreducible background consists of genuine photons pairs continuum. ~125 fb/GeV @ NLO for mH=120 GeV (after cuts and photon efficiency)

Reducible background comes from jet-jet and gamma-jet events in which one or both jets are misidentified as photons (reducible/irreducible cross section (LO-TDR) 2106 (jj) and ~8102 (j)

excellent jet rejection factor (>103) for 80% efficiency sever requirements on particle identification capabilities of the detector

especially the electromagnetic calorimeter


H

b

b

ttHttbb blbjjbb

H

qqH qq

S=130, B=4300, S/B=2 S=15, B=45, S/B=2.2 S=10, B=10, S/B=2.7


3 (complementary) channels with similar (small) significances

different production and decay modes different backgrounds different detector/performance requirements

ECAL crucial for H (in particular response uniformity) : /m ~1% needed

b-tagging crucial for ttH : 4 b-tagged jets needed to reduce combinatorics

efficient jet reconstruction over ||<5 crucial for qqHqq (forward jet tag and central jet veto needed against background)

All three channels require very good understanding of detector performance and background control to 1-10% convincing evidence likely to come later than 2008


Eve

nts

/ 0.

5 G

eV

ATLAS + CMSpreliminary

1

10

10-1

Needed Ldt (fb-1)per experiment

mH (GeV)

1 fb-1 for 98% C.L. exclusion 5 fb-1 for 5 discoveryover full allowed mass range

--- 98% C.L. exclusion

H 4l : narrow mass peak, small backgroundH WW ll (dominant at the Tevatron): counting channel (no mass peak)

here discovery easier with gold-plated H ZZ 4l by end 2008 ?


eeH muonmuon

electronelectronelectronelectron

Signal expected in ATLASafter ‘early' LHC operation


B physics with first datams with BsDs

given the low value measured by CDF ATLAS will be able to measure ms with ~10 fb-1 (one year)

Nevents after trigger + offline rec. 30 fb-1 Models used in MC or to confront experimental sensitivities.

Signal Backgr

Bs→D-s

Bs→D-sa1

+

ms 8250

4060

<100%

<100%

NP: Ball,Khalil, Phys.Rev.D69:115011,2004

133.018.0 07.03117:

ps.mCDF s

D0 :17 ms 21 ps 1 @90% c.l.

CP violation in BsJ/s = -2 = -2 tiny in SM (-0.0360.003 from CKMfitter) and not accessible by any of the LHC experiments

New Physics could lead to enhanced and measurable CP violation8 parameters extracted in maximum likelihood fir to angular distribution of the decayA||(t=0), AT(t=0), 1, 2, ms, s

to avoid failing a fit due to high xs-s correlation xs was fixed

(s)~0.046 for xs=20 ps-1, (s)/s=13%, (s)/s=1%

Models used in MC or to confront experimental sensitivities.

Nevents after trigger + offline rec. 30 fb-1

Signal Backgr

270ks

s

SM: Fleisher CERN-TH-2000-101

NP: Ball,Khalil, Phys.Rev.D69:115011,2004

15%

Bs→J/

xs


BTW: why am I here ?

HELEN (High Energy Latin American European Network) students in physics groups engineers in computing groups

VenezuelaFrance physics groups

A. Cimmarusti (ULA) in Paris for top quark

H. Martinez (ULA) in Paris for Higgs

computing groups G. Diaz (CECALCULA) in Lyon for Tier1

V. Mendoza (Paris for Tier2)

new “bunch” ~March 2007

FranceVenezuela physics groups

J. Malclès (Paris) in Mérida

F. Derue (Paris) in Mérida


Conclusion

New LHC schedule machine and experiments closed 31 August 2007 commissioning run at s=900 GeV end 2007 first physics run at 14 TeV starting in spring 2008

Experiments on track to meet above schedule. Test-beam and cosmics results indicate they work as expected

All efforts now to continue installation and commissioning of machine and detectors of unprecedented complexity, technology and performance

With the first collision data (1-100 pb-1) at 14 TeV: understand detector performance in situ in the LHC environment, and perform first physics measurements

measure particle multiplicity in minimum bias (a few hours of data taking…) measure QCD jet cross-section to ~30% ?

(expect >103 events with ET(j)>1 TeV with 100 pb-1)

measure W, Z cross-sections to 10% with 100 pb-1 ? observe a top signal with ~30 pb-1

measure tt cross-section to 20% and m(top) to 7-10 GeV with 100 pb-1 ? improve knowledge of PDF (low-x gluons !) with W/Z with O(100) pb-1 ? first tuning of MC (minimum bias, underlying event, tt, W/Z+jets, QCD jets…)


Conclusion

And, more ambitiously discover SUSY up to gluino masses of ~1.3 TeV ? discover a Z’ up to masses of ~1.3 TeV ? surprises ?

Later on the LHC will explore in detail the highly-motivated TeV-scale with a direct discovery potential up to m~5-6 TeV

if New Physics is there, the LHC will find it it will say the final word about the SM Higgs mechanism and many TeV-scale predictions it may add crucial pieces to our knowledge of fundamental physics

impact also on astroparticle physics and cosmology most importantly : it will likely tell us which are the right questions to ask,

and how to go on

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