1 / 23

The LHCb Experiment

The LHCb Experiment. presented at Hadron99, Beijing, 24-28 August 1999 On behalf of the LHCb Collaboration Tatsuya Nakada * CERN, Switzerland * on leave from PSI. Introduction

lane-avery
Download Presentation

The LHCb Experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The LHCb Experiment presented at Hadron99, Beijing, 24-28 August 1999 On behalf of the LHCb Collaboration Tatsuya Nakada* CERN, Switzerland *on leave from PSI

  2. Introduction CP violation is observed only in the neutral kaon system:e: CP violation in K-K oscillationse: CP violation in the decay-oscillation interplaye: CP violation in the decay amplitudesThey are within the framework of the Standard Model: KM phase. However, 1) no “precision” test has been made… (difficult with the kaon system due to theoretical uncertainties)2) no real understanding, on the origin of the mass matrix… (Why strong CP is small but weak CP not?)3) Cosmology (baryon genesis) suggests that an additional source of CP violation other than the Standard Model is needed. A lot of room fornew physics  B-meson systems _

  3. The B-meson system is an ideal place to search for new physicsthrough CP violation. 1) For some decay modes, the Standard Model predictions can be made accurately.- precision tests -2) CP violation can be seen in many decay channels.- consistency tests - The system allows to extract the parameters for both the Standard Model and new physics, if it exists.  a simple demonstration to follow

  4. CKM Unitarity Triangles VtdVud + VtsVus + VtbVub = 0 VtdVtb + VcdVcb + VudVub = 0  Vub  Vtd Vtd Vub      Vcb Vts arg Vcb = 0, arg Vub = , arg Vtd = , arg Vts = 

  5. Extensions to the Standard Model Supersymmetry, left-right symmetric model, leptoquark, … etc. all introduces new flavour changing neutral currents Db = 1 process: Decays through penguin Db = 2 process: Oscillations through box through tree b d, s newparticles b d, s l or l d,s b newparticles b d, s l or l newparticles d,s b

  6. CKM and new physics in the oscillation amplitudes |Vtd*Vtb|2 _ _ HB-B[{(1 - r)2 + h2}+ rdb]e2i(b+ fdb) Bd-Bd oscillations Dmd CP in BdJ/y KS |Vts*Vtb|2 _ _ Bs-Bs oscillations HB-B[ l-2+rsb]e-2i(dg+ fsb) Dms CP in Bs J/y f CP in Bd J/y KS b c due to the interference J/y c W Bd Bd J/yKS Bd Bd s KS _ d d _ HB-Be-2i(b+ fdb) ABJ/yKsVcb* Vcse0i

  7. CP violation in Bd J/y KS v.s. Bd J/y KS measures 2bJ/yK = 2(bKM + fdb) _ CP violation in Bd D*+ np v.s. Bd D*- np Bd D*- np v.s. Bd D*+ np measures 2(bKM + fdb)+gKM _ _ A consistency test bycomparing the two gKMthen combine them to improve the precision CP violation in Bs J/yf v.s. Bs J/yf measures 2bJ/yf = 2(dgKM + fsb) CP violation in Bs Ds+ K- v.s. Bs Ds- K+ Bs Ds- K+ v.s. Bs Ds+ K- measures 2(dgKM + fsb)+gKM _ _ _

  8. semileptonic decaysare least effected bynew physics |Vtd| = (1 - rKM)2 + hKM2 h Measured Gbu rKM2 + hKM2 bKM: CKM angle Vtd e-ibKM hKM r 1 rKM MeasuredgKMfromCP violation inBdD*np, BsDsK

  9. 1) gKM is determined determination ofCKM parameters 2) |Vub| and gKM bKMor (rKM, hKM) 3) hKM dgKM 4) (rKM, hKM)  |Vtd| and |Vts| 5) bJ/yK and bKM fdb determination of new physicsparameters 6) bJ/yf and dgKM fsb 7) Dms, Dmd and (rKM, hKM)  rdband rsb Both CKM and New Physics parameter sets arefully and cleanly determined. (and many other examples)

  10. Potential problems for BaBar, BELLE, CDF, D0, HERA-B J/yKS very high statistics for a precision D*np small asymmetries require high statistics, low background DsK need Bs (problem for BaBar, BELLE)particle ID at large p (problem for CDF, D0) small branching fractions <10-5 require high statistics J/yf need Bs (problem for BaBar, BELLE)large statistics needed to obtain CP=+1/CP=-1

  11. The LHCb experiment Operating at the most intensive source of Bu, Bd, Bs and Bc,i.e. LHC with -particle identification-trigger efficient for both leptonic and hadronic final states.(ATLAS and CMS: no real particle ID and only with lepton triggers)

  12. USA Brazil Ukraine Finland France UK Switzerland Germany Poland PRC Netherlands Romania Russia Italy Spain The LHCb Experiment(~450 people, ~50 institutes)

  13. The LHCb Collaboration (August 99)Finland: Espoo-Vantaa Inst. Tech. France: Clermont-Ferrand, CPPM Marseille, LAL Orsay Germany: Humboldt Univ. Berlin, Univ. Freiburg, Tech. Univ. Dresden, Phys. Inst. Univ. Heidelberg, IHEP Univ. Heidelberg, MPI Heidelberg, Italy: Bologna, Cagliari , Ferrara, Genoa, Milan, Univ. Rome I (La Sapienza), Univ. Rome II(Tor Vergata) Netherlands: Univ. Amsterdam, Free Univ. Amsterdam, Univ. Utrecht, FOM Poland: Cracow Inst. Nucl. Phys., Warsaw Univ. Spain: Univ. Barcelona, Univ. Santiago de Compostela Switzerland: Univ. Lausanne UK: Univ. Cambridge, Univ. Edinburgh, Univ. Glasgow, IC London, Univ. Liverpool, Univ. OxfordCERN Brazil: UFRJ China: IHEP(Beijing), Univ. Sci. and Tech.(Hefei), Nanjing Univ., Shandong Uni. Russia: INR, ITEP, Lebedev Inst., IHEP, PNPI(Gatchina) Romania: Inst. of Atomic Phys. Bucharest Ukraine: Inst. Phys. Tech. (Kharkov), Inst. Nucl. Research (Kiev) U.S.A.: Univ. Virginia, Northwestern Univ., Rice Univ.

  14. IP 8

  15. The LHCb Detector Vertex detector: Si r-f strip detector, single-sided, 150mm thick, analogue readout Tracking system: Outer; drift chamber with straw technology Inner; Micro Strip Gas Chamber with Gaseous Electron Multiplier, Micro Cathode Strip Chamber or Si RICH system: RICH-1; Aerogel (n = 1.03) C4F10 (n = 1.0014) RICH-2; CF4 (n = 1.0005) Photon detector; Hybrid Photon Diodes (backup solution PMT) Calorimeter system: Preshower; Single layer Pb/Si (14/10 mm) Electromagnetic; Shashilik type 25X0, ~10% resolution Hadron; ATLAS design tile calorimeter 5.6l, <80% resolution Muon system: Multi-gap Resistive Plate Chamber or Thin Gap Chamber and Cathode Pad Chamber

  16. Physics capability of the LHCb detector is due to: -Trigger efficient for both lepton and hadron high pT hadron trigger 2 to 3 times increase inpp, Kp, D*p, DK*,Dsp, DsK … Dsp: 34k (flexible and robust) -Particle identification e/m/p/K/ppp, Kp, D*p, DK*, Dsp, DsK -Good mass resolution e.g. 11 MeV for Bs Dsp, 17 MeV for Bd p+p-(particle ID + mass resolution redundant background rejection) -Good decay time resolution e.g. 43 fs for Bs Dsp, 32 fs for Bs J/yf

  17. Trigger: Flexible: Multilevel with different ingredients Robust: Evenly spread selectivitiesover all the levels Efficient: High pTleptons andhadrons (Level 0)Detached decay vertices (Level 1)

  18. LHCb Trigger Efficiency for reconstructed and correctly tagged events L0(%) L1(%) L2(%) Total(%)  e h all BdJ/(ee)KS + tag 17 63 17 72 42 81 24 BdJ/()KS + tag 87 6 16 88 50 81 36 BsDsK + tag 15 9 45 54 56 92 28 BdDK        Bd + tag 14 8 70 76 48 83 30 -trigger efficiencies are ~ 30% -hadron trigger is important for hadronic final states -lepton trigger is important for final states with leptons

  19. Bs DsK Major background: Bs Ds(No CP violation) Importance of particle identification and mass resolution

  20. _ Bs-Bs oscillations with BsDs 120 k reconstructed and tagged eventsmeasurements of mswith a significance >5: up to psxs

  21. The LHCb detector, a forward spectrometer with particle ID, will have a wide programme in heavy flavour physics. • CP violation: Bd  p+p-rp K±pmfKS K*0g K*0l+l- … Bs  K+K- K±pmfffKSfgfl+l- … • rare and forbidden decays: Bs, d  m+m-, m±em ... • Bc meson decays • b-baryon spectroscopy • etc. tree + penguin penguin only

  22. Conclusions • LHCb has been approved in September 1998,  preparing for Technical Design Reports. • Construction will start the beginning of 2001. • LHCb is one of the four baseline LHC experiments, taking data from the day one. • Efficient and robust trigger  the optimal luminosity 21032exploiting the physics potential from the day one. • Locally tuneable luminosity  long physics programme. • Effective trigger, particle ID, decay time and mass resolution essential to reveal New Physics from CP violation. (not possible by the general purpose LHC experiments)

  23. LHCb CP Sensitivities in 1 year (work still in progress) Parameter Channels No of events (1 year) LHCb feature 2(+) Bd + c.c. 6900 |P/T| = 0 2-5 PID, hadron trigger Bdr + c.c. ~1000 in progress PID, hadron trigger 2+ Bd  D* 446000 9 PID, hadron trigger  BdJ/Ks 45000 0.6 -2 Bs DsK 24000 6-13 PID, hadron trigger, t  Bd  DK* 400 10 PID, hadron trigger  Bs  J/yf 44000 0.6 t Bs oscillations xs Bs  Ds 120000 upto 75 hadron trigger, t Rare Decays Br Bs   <210-9 t No. Bd  K*  26000 photon trigger

More Related