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b – физика на LHCb

А.И. Голутвин (ИТЭФ). b – физика на LHCb. Нарушение Редкие распады CP чётности. LHCb – forward spectrometer (running in pp – collider mode) Data taking starts next year Expect ~10 fb -1 by 2013

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b – физика на LHCb

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  1. А.И. Голутвин (ИТЭФ) b – физика на LHCb Нарушение Редкие распады CP чётности

  2. LHCb – forward spectrometer (running in pp – collider mode) • Data taking starts next year • Expect ~10 fb-1by 2013 • B physics is also a part of the ATLAS and CMS early program • LHCb is designed to run at an average luminosity of 2 1032 and be able to • handle 51032 cm-2s-1 for short periods • For a “nominal” year of 107 seconds this corresponds to 2 fb-1 . Most physics • goals are expressed in terms of the reach for 10 fb-1 (i.e. 5 nominal years) • Super LHCb (SLHCb) willrun at 10 times • the initial design luminosity with twice more efficient trigger • and record data sample of > 100 fb-1 • Start data taking after 2014 • Working Group set up to identify the R&D required to make an upgrade of LHCb feasible, • and to make the physics case • Issues of triggering, fast vertex detection, electronics, radiation dose, handling the pile-up and higher occupancy, etc… • → Expression of Interest for R&D towards an upgrade is in preparation

  3. LHCb Collaboration LHCb is a collaboration of ~ 670 members from 48 institutes • in Brazil, China, France, Germany, Ireland, Italy, Poland, Romania, Russia, Spain, Switzerland, Ukraine, UK, and the US Российские Институты: ИТЭФ(Москва), ИФВЭ(Протвино), ИЯИ(Троицк), ПИЯФ(Гатчина), ИЯФ(Новосибирск) внесли определяющий вклад в создание калориметрической системы и мюонного детектора Планируется вступление в коллаборацию НИИЯФ МГУ

  4. The LHCb Experiment 10 – 300 mrad forward acceptance • Forward geometry • Running with less focused beam is sufficient At 21032 1012 bb pairs are produced per year p Dipole magnet Interaction point p

  5. Experimental infrastructure Shielding wall(against radiation) Most detectors open transversely for access Electronics + CPU farm in barracks (Control Room on surface) Offset interaction point To maximize space

  6. Shielding wall • Upper part completed Labour intensive “Egyptian work” as inaccessible by crane… • Assembly of lower part is progressing wellPaused while a problem with leaking cooling-water pipes is investigated

  7. Calorimeters Magnet Muon detector RICH-2 OT RICH-1 VELO It’s full! Installation of major structures is essentially complete Commissioning is ongoing !

  8. UT as a standard approach to test the consistency of SM Mean values of angles and sides of UT are consistent with SM predictions • Accuracy of sides is limited by theory: • Extraction of |Vub| • Lattice calculation of Accuracy of angles is limited by experiment: • = ±13° • b = ± 1° • = ± 25°

  9. Search for NP comparing observables measured in tree and loop topologies (peng+tree) in B,, (peng+box) in BKs (peng+box) in Bs (tree+box) in B J/Ks (tree) in many channels (tree+box) in Bs J/ New heavy particles, which may contribute to d- and s- penguins, could lead to some phase shifts in all three angles: (NP) = (peng+tree) - (tree) (NP) = (BKs) - (BJ/Ks) ≠ 0 (NP) = (Bs) - (BsJ/)

  10. Search for NP comparing observables measured in tree and loop topologies • Contribution of NP to processes mediated by loops • (present status) • to boxes: •  vs |Vub / Vcb | is limited by theory (~10% precision in |Vub|) (d-box) •  not measured with any accuracy (s-box) • to penguins: • ((NP)) ~ 30° (d-penguin) • ((NP)) ~8°(s-penguin) • ((NP)) not measured (s-penguin) • PS (NP) =  (NP) • (NP) measured in B and B decays may differ depending • on penguin contribution to  and  final states

  11. : LHC prospects BsJ/ is the Bs counterpart of B0J/ KS • In SM S = - 2arg(Vts) = - 22 ~ - 0.04 • Sensitive to New Physics effects in the Bs-Bs system if NP in mixing S = S(SM) + S(NP) • 2 CP-even, 1 CP-odd amplitudes, angular analysis needed to separate, then fit to S, S, CP-odd fraction • LHCb yield in 2 fb-1 131k, B/S = 0.12 LHCb 0.021 0.021 ATLAS will reach s(s) ~ 0.08 (10/fb, ms=20/ps, 90k J/ evts)

  12. UT angle g : LHCb (BaBAr & BELLE & Tevatron ~12° precision for  at best) • Interference between tree-level decays Favored: VcbVus* Vcs* Vub: suppressed u s Common final state K(*)- K(*)- s u u b B- B- b c c u D(*)0 D(*)0 u u f Parameters:γ, (rB, δB) per mode • Three methods for exploiting interference (choice of D0 decay modes): • (GLW): Use CP eigenstates of D(*)0 decay, e.g. D0  K + K- /π+π– , Ksπ0 • (ADS): Use doubly Cabibbo-suppressed decays, e.g. D0  K+π- • (Dalitz): Use Dalitz plot analysis of 3-body D0 decays, e.g. Ks π+ π- • Mixing induced CPV measurement in Bs Ds K decays • Specific for LHCb

  13. B± → D(KSπ+π−) K± hep/ph 0703267 B- B+ • Mode used by B factories to give best existing constraint on CKM angle g: Simulated data for LHCb (1 year) (stat, syst, model) • ~ 400 events each • LHCb yield ~ 5000 events/2 fb-1 • Spot the difference between the Dalitz plots for B+ and B-→ effect of CP violation • Binning can reduce model dependencePrecision on g ~ 12º (in one year) LHCb status report

  14. angle  ( 3 ) at SFF Model-independent approach A.Bondar, A.Poluektov Eur.Phys.J C47,347(2006) hep-ph/0510246 • 50 ab-1 at SFF factory • should be enough for • model-independent γ/φ3 • measurement with accuracy • below 2° • 1fb-1 at ψ(3770) corresponds • 2100 CP-tagged KS+- events • (first estimation based on CLEO-c • data by David Asner) • ~10 fb-1 at ψ(3770) needed to • accompany SuperB measurement

  15. UT angle g : LHCb summary table Combined precision after 2 fb-1()  5 (from tree only)

  16. LHCb (10fb-1 ) and SFF (50-75 ab-1) & SLHCb (>100 fb -1) sensitivities LHCb SFF & SLHCb SLHCb (stat. only) ~ 0.003 < 1 (BsDsK) - - - > 2014 S(K0S) 0.02-0.03 S() 0.01

  17. Search for New Physics in Rare Decays • Exclusive b  s • BK* • Bs • B  tn, hnn, ... • B  s, sll inclusive We are just approaching sensitivity promising for discovery… LHCb SFF Experimental challenge: keep backgrounds under control

  18. b  s exclusive Bs  BELLE observed 16±8 events 2 weeks run at (5S); no TDCPV LHCb control channel: Bd K* ~75k signal events per 2fb-1 LHCb annual yield ~11k with B/S < 0.6

  19. b  s exclusive b   (L) + (ms/mb)  (R) • Measurement of the photon helicity is very sensitive test of SM • Methods: • Mixing induced CP asymmetries in Bs  , BKs 0 • Photon helicity can be measured directly in radiative B decays to final state with  3 hadrons. • Promising channels for LHCb are B K and B K decays Expected yield per 2 fb-1 BR(B+ K+-+) ~ 2.5  10-5rich pattern of resonances ~60k BR(B+ K+) ~ 3  10-6 highly distinctive final state ~ 7k

  20. b  s exclusive • Mixing induced CP asymmetries • BKs0  (B-factories) S = - (2+O(s))sin(2)ms/mb + (possible contribution from bsg) = - 0.022 ± 0.015 P.Ball and R.Zwicky hep-ph/0609037 Present accuracy: S = - 0.21 ± 0.40 (BaBar : 232M BB) S = - 0.10 ± 0.31 (BELLE: 535M BB) • Bs  (LHCb) LHCb sensitivity with 10fb-1 : (A) = 0.09

  21. 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 SM

  22. AFB(s), fast MC, 2 fb–1 s = (m)2 [GeV2] B  K*: LHCb prospects • Forward-backward asymmetry AFB (s) in - • rest frame is a sensitive NP probe • Predicted zero of AFB (s) depends on Wilson • coefficients C7eff / C9eff • 7.2 k events / 2fb-1 with B/S ~ 0.4 • After 10 fb-1zero of AFB located to ±0.28 • GeV2 providing 7% stat. error • on C7eff / C9eff • Full angular analysis gives better • discrimination between models. Looks • promising

  23. Bs   Very smal BR in SM (3.4 ± 0.5) x 10-9 This decay could be strongly enhanced in some SUSY models. Current limit from CDF BR(Bs) < 4710-9(2010-9 expected final D0+CDF limit) With loose selection LHCb expects ~40 signal events (2fb-1/SM BR) on top of ~1500 background events (mostly form b  , b ) Particle ID, vertexing and invariant mass resolution (M  )~ 18 MeV provide excellent separation of signal from background

  24. OUTLOOK Clean experimental signature of NP is unlikely at currently operating experiments • From now to 2014 • A lot of opportunities (LHCb will start data taking next year) • Important measurements to search for NP and test SM in CP violation • : if non-zero  NP in boxes < 2010 •  vs Rb and  vs Rt (Input from theory !) • (NP) and (NP): if non-zero  NP in penguins • in Rare decays • BR(Bs  ) down to SM prediction < 2010 • Photon helicity in exclusive bs decays • FBA & transversity amplitudes in exclusive bsll decays < 2010 After 2014 ATLAS and CMS might or might not discovered New Particles. At the same time LHCb might or might not see NP phenomena beyond SM. In either case it is important to go on with B physics at SFF & Upgraded LHCb Need much improved precision because any measurement in b-system constrains NP models high pT B’s

  25. LHCb calorimeter system • Scintillating Pad Detector / PreShower • Electromagnetic Calorimeter • Hadron Calorimeter • Fast response within 25 ns • is a 1st priority requirement for L0 trigger • All 3 calorimeter are using the “same” technology: absorber/scintillator readout with WLS fibres Front of PS Back of SPD Lead

  26. Inner + Middle + Outer Modules Overview of LHCbSPD and PS PS+SPD built from 16 super modules Side view of upper part Super module with 2 x 13 modules Scintillator + coiled fiber Moving cable trays Super module frame • TDR estimations (2000): • outer ~ 20 ph.el. • inner ~ 30 ph.el. MAPMT+ VFE R/O cables Preshower cosmic test before Super-Module installation # phe/MIP for each tile: Inner: 25 phe Middle 29 phe Outer: 19 phe Andrey Golutvin VCI 2007

  27. 3312 shashlik modules with 25 X0 Pb Two halves on chariots and electronics platform on top Overview of LHCb ECAL Inner module Fibres with loops Middle module Outer module Electron. platform modules PMT and CW base Scintillators, lead-plates, covers Beam plug Front- cover PMT End- cover Chariot CW base TYVEK Scintillator Lead plate

  28. 52 modules with longitudinal tiles CW base Internal cabling PMT housing particles scintillators Chariot Module with optics assembled fibers light-guide PMT Overview of LHCb HCAL Electron. platform modules Beam plug

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