1 / 28

Physics case for LHCb & SuperLHCb Data samples: 10fb -1 in a few years of data taking

Andrei Golutvin Imperial College London & ITEP & CERN. Physics case for LHCb & SuperLHCb Data samples: 10fb -1 in a few years of data taking  current LHCb physics program 100fb -1  plans for LHCb upgrade  SuperLHCb. Search & Study of New Physics at LHC

nola-watson
Download Presentation

Physics case for LHCb & SuperLHCb Data samples: 10fb -1 in a few years of data taking

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. Andrei Golutvin Imperial College London & ITEP & CERN • Physics case for LHCb & SuperLHCb • Data samples: • 10fb-1 in a few years of data taking •  current LHCb physics program • 100fb-1 plans for LHCb upgrade  SuperLHCb SuperB workshop Feb. 2009

  2. Search & Study of New Physics at LHC are the main objectives of the LHCb physics program Thanks to B-factories and CDF/D0 the CKM mechanism of CP violation is proven to be the leading one Extend the parameterization to include possible New Physics contributions to B-B oscillations - Im(Ds) Large range of NP allowed ! SuperB workshop Feb. 2009 Re(Ds)

  3. LHCb strategy Measure experimental observables sensitive to New Particles through their interference effects with well studied objects, b-quarks, in the processes mediated by the loop diagrams: • Bd,s oscillations: box diagram • Penguin diagrams: • Radiative penguin: Bs  • Electroweak penguin: B  K*µµ • Strong penguin: B , Bs Oscillation box q b u,c,t W− W+ q u, c, t b SuperB workshop Feb. 2009 Viq V*ib

  4. The Unitarity Triangle : Bdmixing phase -s: Bsmixing phase : weak decay phase Im    0 1 Re Im  + s Bs J/ψϕ,… -s -s +s 0 Re SuperB workshop Feb. 2009

  5. The Unitarity Triangle Main experimental observables: - |Vub/Vcb| side in trees (exclusive and inclusive semileptonic b-decays) - md /ms side in the ratio of s- and d-boxes (or s- and d- penguins in BK* and B) -  angle in the d-box: BJ/K0 (d-box + s-penguin in B K0 ) - s angle in the s-box: Bs J/ (s-box + s-penguin in Bs ) -  angle in trees (many possibilities in BDX decays) -  angle in trees + penguins in B , ,  (reduced sensitivity to penguins) SuperB workshop Feb. 2009

  6. Accuracy of sides is limited by theory: • Extraction of |Vub| • Lattice calculation of Accuracy of angles is limited by experiment : • = ±13° •  = ± 1° • = ± 20° • s is not measured accurately • Hint for a large value (beyond the SM) from CDF/D0 SuperB workshop Feb. 2009

  7. Search for New Physics • in CPV measurements • In box diagrams •  vs |Vub / Vcb | is largely limited by theory (~10% precision in |Vub|) (d-box) • Note a discrepancy in |Vub| determined in inclusive and exclusive • measurements: |Vub| incl ~ (4.0-4.5) 10 -3 and |Vub| excl ~ (3.0-3.5) 10 -3 •  vs md /ms is limited by experiment:  is poorly measured (± 20°) Indirect Directmeasurement Indirectly  is determined to be g = (68 ± 5)º from the processes involving loops LHCb will measure  directly in trees: () ~ 2-3 (10 fb-1 sample) SuperB workshop Feb. 2009

  8. Search for New Physics • in CPV measurements • In box diagrams • S = -2S is the counterpart of d = 2 • s not measured accurately (indication of large value from CDF/D0) (s-box) • Theoretical uncertainty is much smaller than for  • S (J/)[SM] = 0.0368±0.0017 (CKMfitter 2007) SM consistency at 7% level LHCb prospects (10 fb-1sample) Expected yield 575k BJ/ events (s) ~ 0.01 SuperB workshop Feb. 2009

  9. Search for New Physics • in CPV measurements • In penguin diagrams: • (NP) = (BKs) - (BJ/Ks)  0 • s (NP) = s (Bs) - s (BsJ/) • ((NP)) ~10° (s-penguin) • (s (NP)) not measured (s-penguin) • PS  (NP)  s (NP) LHCb prospects (10 fb-1 sample): (s) ~ 3 () ~ 6 SuperB workshop Feb. 2009

  10. Search for New Physics in Rare Decays (combination of various box and penguin diagrams) • Experiments are just reaching an interesting level of sensitivity • in exclusive decays: • BR (Bs  µµ) (CDF /D0) • BR (Bd  ) • Photon polarization in B  K* (BELLE/BaBar) • AFB in B  K*µµ (BELLE/BaBar) • BR (D0  µµ) (CDF) • Lepton Flavor Violation in  decays (BELLE/BaBar) • Contribution from LHCb is extremely important !!! SuperB workshop Feb. 2009

  11. Bs   • Super rare decay in SM with well • predicted BR(Bs  µµ) = (3.55±0.33)×10-9 • Sensitive to NP in MSSM • BR  tan6 / M4A • Best present limit is from CDF: • BR(Bs  µµ) < 4.7×10-8 @ 90% CL • For the SM prediction • LHCb expects 8 signal and 12 • background events in the most • sensitive bin in 2 fb-1 . Background is • dominated by semileptonic decays • of different b quarks • 3 evidence with 2 fb-1 • 5 observation with 6fb-1 CDF SuperB workshop Feb. 2009

  12. Measurement of the photon polarization in Bs   decay b   (L) + (ms/mb)  (R)  produced in Bs and Bs decays do not interfere in SM  corresponding ACP = 0 • SM: • C = 0 direct CP-violation • S = sin2 sin • A = sin2cos • Expected signal yield is 55k for 10 fb-1 • Sensitivity: (A) = (sin2) assuming cos1 = 0.09 for 10fb-1 • To be compared with current accuracy from B-factories: (sin2) ~ 0.4 SuperB workshop Feb. 2009

  13. B  K* In SM this bs penguin decay contains right-handed calculable contribution but this could be added to by NP resulting in modified angular distributions • Described by three angles (ql, f, qK) and di-m invariant mass q2 • Forward-backward asymmetry AFBof qldistribution of particular interest: • Varies between different NP models → • At zero-point, dominant theor. uncert. from Bd→K*form-factors cancels at LO SuperB workshop Feb. 2009

  14. B  K* • Forward-backward asymmetry AFB (s) in - • rest frame is a sensitive NP probe • Predicted zero of AFB (s) depends on Wilson • coefficients C7eff / C9eff LHCb, 10 fb-1 • ~7k events / 2fb-1 with B/S ~ 0.2 • After 10 fb-1zero of AFB located to ±0.28 • GeV2 (0.5 GeV2 after 2 fb-1) • providing 7% stat. error on C7eff / C9eff • Full angular analysis gives better • discrimination between models. SuperB workshop Feb. 2009

  15. Charm Physics • Charm has unique sensitivity to NP since loop diagrams involve • down-type quarks • Precision measurements of x & y, mixing parameters in the • charm system (factor of 5 improvement wrt current accuracy) • Wrong Sign (D0  - K+ ) mixing analysis • with 10 fb-1 N(ws) = 232500 • x 2 ± 0.064 (stat.) ( ×10-3 ) & y ± 0.87 (stat.) ( ×10-3 ) • Singly Cabibbo Suppressed 2-body lifetime ratio • measurement of yCP : D0 K- K+, - + • with 10 fb-1 N(D0 K- K+ from secondary D*+) ~ 8 ×106 • yCP ± 0.05 (stat.) x = x cos + y sin y = y cos - x sin SuperB workshop Feb. 2009

  16. Charm Physics • CP Violation in the charm sector is extremely small in SM • CP asymmetries possible in mixing (AM) or in between mixing and decay(AI ) • AM -y/2(|q/p| - |p/q|)×cos() & AI x/2(|q/p| + |p/q|)×sin() • Both  and (|q/p| - 1) are negligibly small in SM • Existing limits: • |q/p| = 0.87 ± 0.180.15 &  = -9.1 ± 8.17.8 degree • Higher sensitivity will come as mixing analyses improve precision •  Sensitivity to many NP models • Example: CPV in Singly Cabibbo Suppressed decays (NP in penguins) • D0 KK,  • With 10 fb-1 statistical sensitivity on Acp will reach 10 -3 level • May be observable ! SuperB workshop Feb. 2009

  17. If NP is discovered by LHCb with 10 fb-1 the NP models should be studied Plan for LHCb upgrade to collect ~100 fb-1 There are many observables where we are not limited by theoretical uncertainties SuperB workshop Feb. 2009

  18. CPV measurements • Sensitivity • with 10 fb-1 Do we need 100 fb-1? • NP in boxes: • s is the most sensitive • measurement (s) ~ 0.01 Yes • (theor. uncert. 0.002) • NP in penguins: • Probably the best sensitivity: Yes • s in Bs J/ • & Bs  (s) ~ 0.05 • or  in B  J/Ks Yes • & B  Ks () ~ 0.1 SuperB workshop Feb. 2009

  19. Rare Decays • Sensitivity • with 10 fb-1 Do we need 100 fb-1 ? • NP in penguins: • Photon polarization • in Bs  decay: (A)= 0.09 Yes • (theor. uncert. ~0.01) • NP in a mixture of loop diagrams: • B  K*µµ (s0) ~ 0.3 GeV2 Yes (assuming • theor. progress) • Bs µµ >5 observation if SM Yes • ( Bd µµ ) • Charm Physics Measured CP asymmetries • approach SM prediction • LVF in  decays BR(3µ) < 10-8 • using  from Ds  There could be great possibilities To be explored ! SuperB workshop Feb. 2009

  20. LHCb sensitivities for integrated lumi of 100 fb-1 Also studying Lepton Flavour Violation in  SuperB workshop Feb. 2009

  21. Physics: main objectives Search for New Physics in CP-violation and Rare Decays • Key Measurements Accuracy in 1 nominal year • (2 fb-1) • In CP – violation • s 0.023 •  in trees 4.5 •  in loops 10 • In Rare Decays • B  K* (s0) = 0.5 GeV2 • Bs  3 measurement down to SM prediction • Polarization of photon • in radiative penguin decays (A) = 0.2 (in Bs) SuperB workshop Feb. 2009

  22. Physics: main objectives Search for New Physics in CP-violation and Rare Decays • Key Measurements Sensitivity with 10 fb-1 • (few years of data taking) • In CP – violation • s 0.01 •  in trees 2-3 •  in loops 5 • In Rare Decays • B  K* (s0) = 0.28 GeV2 • Bs  5 measurement down to SM prediction • Polarization of photon • in radiative penguin decays (A) = 0.09 (in Bs) SuperB workshop Feb. 2009

  23. Conclusion on physics case • A clear experimental signature of New Physics unlikely to be • discovered at currently operating experiments • LHCb has many opportunities to discover NP in flavour sector within • a few years of data taking (10 fb-1 sample); complementary to direct • search by ATLAS & CMS • Preparing the LHCb upgrade to collect 100fb-1 is very important to study NP models • Since the luminosity is limited for the first phase of LHCb the time • to double statistical precision will become long, after a few years of • stable operation SuperB workshop Feb. 2009

  24. LHC and Luminosity SuperB workshop Feb. 2009

  25. Limitations of LHCb running at high luminosity • At L > 2×1032 no hadron trigger gain • Need for the trigger upgrade to improve • hadron trigger efficiency •  Requires adding the impact parameter • information in first level •  Requires replacement all FE with • 40 MHz read-out electronics • Tracking & Particle ID performance • Radiation resistance of sub-detectors • (particularly affects large η) Below L ~ 1033 only trigger needs upgrade Above L ~ 1033 major LHCb upgrade is required to improve tracking & particle ID performance well as radiation resistance of the innermost LHCb parts SuperB workshop Feb. 2009

  26. Upgraded hadron trigger for Bsϕϕ • At L=2×1032 upgraded trigger improves • efficiency from 16% to 55% by • reducing the threshold for ET of hadron • clusters from 4 GeV down to 2 GeV • Similar signal efficiency at increased • L = 1033; i.e. >10 times better signal yield • for 5 times increased luminosity • Resulted trigger rate ~ 500 kHz without • any tuning. ( “Tuned” to get rate down • ~ 30 kHz for ~45% signal efficiency) Trigger steps SuperB workshop Feb. 2009

  27. LHCb upgrade schedule • has to be well integrated into the schedule • of LHC and General Purpose Detectors (GPD) • 1st long shutdown to install GPD triplets • 2nd long shutdown to install GPD inner • detectors • Schedule A consider 2 upgrade phases: • - Upgrade FE electronics to 40 MHz readout • and trigger. Run at L~1033 until 2nd shutdown • - Major upgrade of LHCb during 2nd shutdown • Run at L ≥ 3×1033 after ~2018 • Schedule B combines 2 phases • At some point increase luminosity up to 1033 and • run until major LHCb upgrade with the muon • trigger only SuperB workshop Feb. 2009

  28. Various Scenarios to happen in the next few years No space left for the 4th possibility Even if 4th possibility  LHCb, and superB, measurements of virtual effects may be the only way to set scale of BSM physics SuperB workshop Feb. 2009

More Related