Presentation is loading. Please wait.

Presentation is loading. Please wait.

J/ Production at the LHC Giulia Manca (University of Cagliari and INFN, Italy) 7 th Workshop on B Physics Orsay, France 4 th –5 th October 2010.

Similar presentations


Presentation on theme: "J/ Production at the LHC Giulia Manca (University of Cagliari and INFN, Italy) 7 th Workshop on B Physics Orsay, France 4 th –5 th October 2010."— Presentation transcript:

1 J/ Production at the LHC Giulia Manca (University of Cagliari and INFN, Italy) 7 th Workshop on B Physics Orsay, France 4 th –5 th October 2010

2 Outline Motivation Cern and the LHC The experiments J/ production and results Conclusions and outlook 4.10.20102Giulia Manca

3 CERN and the LHC 4.10.20103Giulia Manca p p pp collider : NOW : @ s = 7 TeV L 1-2·10 31 cm -2 s -1 NOMINAL (2011) : s =14 TeV L = 2·10 32 cm -2 s -1 (LHCb specific)

4 The four LHC Detectors 4.10.20104Giulia Manca p p

5 Rapidity Range 4.10.2010Giulia Manca5

6 Luminosity 4.10.20106Giulia Manca LHC running well, all experiments have an efficiency 90% Already more than 3 pb -1 on tape These analyses : L 9-100 nb -1 Goals : 1 pb -1 (August 2010) 100 pb -1 (end of 2010) 1 fb -1 (end of 2011) Mar 2010 May 2010 July 2010

7 Motivations The production mechanism in pp collisions still unclear Several models around : Color singlet and color octet mechanisms (NRQCD) describe the p T spectrum and cross section of the J/ as measured by Tevatron, but not the polarization (and has other failures) Other models such as color evaporation model, kt factorization, soft color interaction model cannot describe the data either New data from LHC experiments will help to resolve this issue 4.10.2010Giulia Manca7 J/ cross section crucial milestone in understanding detector and first step to B cross section measurement

8 4.10.2010Giulia Manca8 J/ Production J

9 4.10.2010Giulia Manca9 J/ Production J

10 J/ Production at pp 4.10.2010Giulia Manca10 1 st step2 nd step3 rd stepProduction type Prompt,direct Prompt,indirect Delayed,indirect BR(J/ψ )6% s=10 TeV LO color singlet+color octet J.Lee, H.S. Chung hep-ph/0412158 Pythia 6.4 s=7 TeV 10< <400 mrad LHCb MC samples (unpolarised J/ψ) Prompt J/ at LHC

11 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 y of J/ J/ Acceptance 4.10.2010Giulia Manca11 Total Acceptance13% LHCb Acceptance 85% LHCb CMS ATLAS CMS ATLAS LHCb ALICE Total Acceptance2-8% ATLAS Acceptance 80% Total Acceptance20% ATLAS Acceptance 85%

12 J/ mass distribution J/ rate 300/nb -1 4.10.201012Giulia Manca Data Observed =70 MeV/c 2 With high purity muons: =29 MeV/c 2 |y|<1.4 target: =70 MeV/c 2 (half in ee channel) Most recent plots ~13 MeV/c 2 LHCb CMS ATLAS ALICE 2.5 { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/2/619379/slides/slide_12.jpg", "name": "J/ mass distribution J/ rate 300/nb -1 4.10.201012Giulia Manca Data Observed =70 MeV/c 2 With high purity muons: =29 MeV/c 2 |y|<1.4 target: =70 MeV/c 2 (half in ee channel) Most recent plots ~13 MeV/c 2 LHCb CMS ATLAS ALICE 2.5

13 Inclusive cross section measurements 4.10.2010Giulia Manca13 LHCb CMS ATLAS ALICE 2.5 { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/2/619379/slides/slide_13.jpg", "name": "Inclusive cross section measurements 4.10.2010Giulia Manca13 LHCb CMS ATLAS ALICE 2.5

14 Cross section measurements 4.10.2010Giulia Manca14

15 J/ proper time/decay lenght 4.10.201015Giulia Manca LHCb CMS ATLAS t z =Δz/p z *M J/ψ t z used to separate J/ prompt from J/ from B

16 Non prompt J/ 4.10.2010Giulia Manca16

17 Influence of J/ Polarisation 4.10.2010 Giulia Manca Detector acceptance as a function of helicity angle cos J/ – lab virtual flight direction Example: helicity frame MC with no polarisation:LHCb acceptance generates an artificial polarisation large influence of polarisation on measurement First step: Treat polarisation as systematic error; present results in three different polarisation scenarios J/ rest frame 17 Both mu < 300 mrad

18 Different polarisation scenarios 4.10.2010Giulia Manca18 LHCb ATLAS CM S Up to 20%

19 Integrated cross section measurements 4.10.2010Giulia Manca19 Experiment Range Luminosity LHCb (in b) pT<10 GeV, 2.5 { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/2/619379/slides/slide_19.jpg", "name": "Integrated cross section measurements 4.10.2010Giulia Manca19 Experiment Range Luminosity LHCb (in b) pT<10 GeV, 2.5

20 Conclusions and Outlook LHC is in great shape and all experiments are taking data with high efficiency All the analysis tools are in place and start to deliver physics results J/ψ events clearly reconstructed Crucial standard candle for detector understanding as well as cross check of luminosity Cross section measurements probe of non- relativistic QCD theories Results in four experiments compatible. Publications expected by the end of the year (with 2-5 pb -1 ). Polarisation measurement next. LHC is in great shape and all experiments are taking data with high efficiency All the analysis tools are in place and start to deliver physics results J/ψ events clearly reconstructed Crucial standard candle for detector understanding as well as cross check of luminosity Cross section measurements probe of non- relativistic QCD theories Results in four experiments compatible. Publications expected by the end of the year (with 2-5 pb -1 ). Polarisation measurement next. 4.10.201020Giulia Manca

21 Back-up 4.10.2010Giulia Manca21

22 Inclusive cross section measurements 4.10.2010Giulia Manca22 Extrapolations with PYTHIA 6.4 (LEP hadronization fractions assumed) 1.½ production cross section for b or b in LHCb acceptance 2.Total bb production cross section An independent σ( bb) measurement by LHCb with results in excellent agreement. Averaging: LEP b hadronization fractions TeVatron b hadronization fractions 88.3±4.5±13.0 333±17±49

23 J/ee mass distribution 4.10.2010Giulia Manca23

24 t z used to separate J/ prompt from J/ from B J/ proper time/decay lenght 4.10.201024Giulia Manca Data Observed

25 The LHCb detector pp collision Point Vertex Locator VELO Tracking System Muon System RICH Detectors Calorimeters p p 254.10.2010Giulia Manca Performance numbers relevant to quarkonium analyses: –Charged tracks p/p = 0.35 % - 0.55%, (m)=10-25 MeV/c 2 –ECAL (E)/E= 10% (E/GeV) -1/2 1 % –Muon ID: ( ) = 97%, mis-ID rate ( ) = 1-3 % –Vertexing: proper time resolution 30-50 fs –Trigger: dominantly software Angular acceptance : 10< <300 mrad possibility to reverse field polarity to check for detector asymmetrie s =2. 5 = 7

26 4.10.201026Giulia Manca LHCb Trigger Measure muon trigger efficiencies using trigger lines not involving muons L0 x HLT1 Efficiency J/ψ->

27 P of muon (MeV/c) Muon Reconstruction Efficiency ε( ) = 97.3 ± 1.2 % Tracking system Muon system J/ µ probe µ tag J/ψ used to measure the Muon reconstruction efficiency 4.10.201027Giulia Manca

28 Muon mis-identification π μ misID LHCb 2010 preliminary LHCb 2010 preliminary πμ dominated by decays in flight pμ dominated by combinatorics in muon stations This plots shows the probability to misidentify a pion from Ks and a proton from Lambda as a muon as a function of momentum. 4.10.201028Giulia Manca

29 Primary Vertex resolution 4.10.2010Giulia Manca29


Download ppt "J/ Production at the LHC Giulia Manca (University of Cagliari and INFN, Italy) 7 th Workshop on B Physics Orsay, France 4 th –5 th October 2010."

Similar presentations


Ads by Google