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Physics Analysis Planning for LHCb

Physics Analysis Planning for LHCb. Summary of current CKM results…. (2005). CKM is a coherent picture of CP violation within the SM New Physics will (most likely) appear as corrections on the CKM framework. or appear in places we haven’t looked (yet) ;-). Mission Statement:

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Physics Analysis Planning for LHCb

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  1. Physics AnalysisPlanningfor LHCb

  2. Summary of current CKM results… (2005) • CKM is a coherent picture of CP violation within the SM • New Physics will (most likely) appear as corrections on the CKM framework. • or appear in places we haven’t looked (yet) ;-) Mission Statement: • CKM metrology: determine magnitude and phase of coupling constants of the charged weak interactions • possibly in the presence of NP • Identify (or put limits on) the effects of NP on flavour physics observables

  3. CKM metrology in presence of NP • Drop all observables which depend on loop diagrams, as there could be (hopefully!) competing New Physics amplitudes… • i.e. those which includes Vtd (or Vts) • Only these two are left: phase and magnitude of Vub/Vcb • |Vub/Vcb| seems mission impossible for LHCb • If anyone has suggestion on how LHCb could compete here, please let me know!

  4. Tree processes : NP free  NP should still satisfy these constraints! Testing for NP in Bd mixing Arg(ABB)=2b+2fBd SM fd=0 NP phase = SM phase (Minimal Flavour Violation Scenarios) NP Disfavored by Asl

  5. Tree processes : NP free Testing for NP in Bs mixing ? I want you to measureDms SM I want you to measure Acp(BsJ/yf)

  6. Size of the Box: Bs mixing (Δms) s b b s – Bs–Bs oscillations: “Box” diagram New particles can augment the SM Box: Phys.Lett.B192:245,1987 msSM  |Vts|4 ? Remember B0d oscillations: • Predicted heavy particle… •  mtop>50 GeV • Needed to break GIM cancellations ms  |Vts2+ANP|2

  7. Bs Mixing Phase : BsJ/ψφ s b b s • Δms is sensitive to |A(BsBs)| • We can also probe the phase of A(BsBs) • Interference of amplitudes Ball et al, Phys.Rev.D69(115011),2004 hep-ph/0311361 Dunietz et al, Phys.Rev.D63(114015),2001 hep-ph/0012219 sinφSM= -Aηλ4/Aλ2 = -ηλ2  -0.03 • Any larger asymmetry means new physics… +

  8. Example NP model: SUSY SO(10) ~ Neutrino mixing angle bR • Superpotential: (16 are fermions, 10 Higgses) • YU contains the large top coupling • YU can be symmetric. In Yu diagonal basis we have: Just as in the SM, we rotate the d-quarks • Break to SU(5) • Break to MSSM (+rh ν): Without neutrino mass, UMNS could be rotated away Chang, Masiero, Murayama Phys.Rev.D67 (075013), 2003, hep-ph/0205111

  9. SUSY SO(10): neutrino mixing  squark smixing Consequences of SO(10) GUT and (drR,dbR,dgR,νL,L) multiplets: • No effect in sR↔bR (i.e. CKM), because there is no right handed coupling • Observable effects in mixing between s̃↔b̃ • The Box Diagram (ΔB=2): • Bs mixing: BsDs-π+ • CP phase: BsJ/ψφ • Penguins & Rare decay (ΔB=1): • Rare decays: BK*μ+μ- • B(s)μ+μ-

  10. Not just SUSY can cause effects…

  11. Rare decays: B(s)μ+μ- &BK*μ+μ- s̃ μ+ s b μ- Tevatron: BR <1.5 10-7 μ+ μ+ s μ- s μ- SM: BR=3.4 10-9 • s̃↔b̃ also appears in Penguin Diagram • Affects rare decay B0K*μ+μ- Ali et al Phys.Rev.D61(074024),2000, hep-ph/9910221 • Similarly, Bsμ+μ-is very promising • SO(10) unifies fermion masses, and predicts: •  tan β = mt(MZ)/mb(MZ)~ 40-50 The “smoking gun” of SO(10) Yukawa unification... Dedes,Dreiner,Nierste Phys.Rev.Lett.87(251804),2001 hep-ph/0108037 Babu,Kolda Phys.Rev.Lett.84(228),2000 hep-ph/9909476 Blazek,Dermisek,Raby Phys.Rev.D65(115004),2002 hep-ph/0201081

  12. Context: Some History

  13. Additional physics within LHCb: • Time-Dependent CP in B0 ‘bc(cs)’ (reference beta) • Time-Dependent CP in B0 ‘bs(ss)’ (beta with penguins) • Time-Dependent CP in B0 ‘bu’ (alpha) • Two body • Quasi Two body • Three body • … • Direct CP in Two-Body ‘bu’ decays, both B0 and Bs • Sensitive to gamma (if s↔d symmetry holds) • B0D(*)K(*), B+D(*)K(*) (ADS,GLW, Dalitz, … ) • Current world’s best g constraint… • But maybe it is based on an upward fluctation of r… • Radiative B-decays (bsg, bdg) • Could determine |Vts/Vtd| without measuring Dms • Mixing and CP in D-decays • Any non-zero observation would be NP… • …

  14. A Theoreticians (G. Isidori) Shopping List

  15. s b b s s b Four Lines of Attack on “bs” This list does NOT include intermediate ‘stepping stones’ or (sometimes very interesting) spin-off • Amix(BsDsp)Acp(BsDsK) • Acp(BsJ/yf) • Br(B(s)mm) • Afb(B0K(*)mm), Afb(bsmm) • These subjects exploit • LHCb advantages over other • experiments: • Bs mesons (1-3) • large production rate (4) • all charged final states • dedicated triggers • propertime resolution • momentum resolution • PID, tagging • And are well matched to our • construction and reconstruction • activities: • OT construction • VELO construction • Track reconstruction

  16. Organisation • Amix(BsDsp) Acp(BsDsK) • 1—2 staf, 1 PostDoc, ~3 OIO • Acp(BsJ/yf) • 1—2 staf, 1 PostDoc, ~3 OIO • Br(Bsmm) • 1—2 staf, 1 PostDoc, ~2 OIO • Afb(B0K(*)mm), Afb(bsmm) • 1—2 staf, 1 PostDoc, ~2 OIO

  17. 1) Open Charm and 2) Charmonium

  18. 1 Time Timeline 1 & 2 2 B-production @LHC 3 5 • Select exclusive B  J/y X • Select exclusive B  D(s)(*)p, D(s)(*)ppp • Determine propertime resolution with exclusive J/yX • Determine propertime resolution & trigger efficiency vs. propertime for/with D(s)(*)p, D(s)(*)ppp • Angular analysis B0J/y K* and Bs J/yf • Measure lifetime ratios with exclusive J/yX • Determine tagging performance, measure/limit Dms • Bs J/yf tagged time-dependent transversity & CP • BsDs(K/p) tagged time-dependent CP 4 6 Tagging 7 Lifetime ratios, DG/G A0,A//,A┴ triple product Dms PID 8 9 Acp(J/yf) g

  19. 1 3) BK*mm and 4) B(s)mm • Select inclusive J/y • Select exclusive B  J/y X • Determine propertime resolution with exclusive J/yX • Angular analysis B0J/y K* and Bs J/yf • Selection of K*mm • Selection of B(s)mm • Determination Afb(K*mm) 2 5 6 3 7 4 J/y K* and y(2S)K* are both background & calibration sample for K*mm J/ymm gives normalization for Br(B(s)mm) Both channels need excellent vertex (VELO) and momentum resolution (OT) to select signal and reject background (due to lack of intermediate resonances)

  20. routemap Routemap Summary & Conclusions • We have defined a physics analysis roadmap • Focus on bs transition in a way which profits from LHCb strong points • And which covers both ‘CKM metrology’ and ‘Physics Beyond SM’ discovery • Roadmap matches our (re)construction efforts • Large part of our plan is well established within the LHCb collaboration • See eg. Reoptimization TDR • And is embedded within LHCb collaboration • GR convener ‘propertime & mixing’ physics group & member ‘Physics Planning Group’

  21. BACKUP

  22. Strengths of indirect approach • Can in principle access higher scales and therefore see effect earlier: • Third quark family inferred by Kobayashi and Maskawa (1973) to explain small CP violation measured in kaon mixing (1964), but only directly observed in 1977 (b) and1995 (t) • Neutral currents (+N +N) discovered in 1973, but real Z discovered in 1983 • Can in principle also access the phases of the new couplings: • NP at TeV scale needs to have a “flavour structure” to provide the suppression mechanism for already observed FCNC processes  once NP is discovered, it is important to measure this structure, including new phases Complementarity with the “direct” approach: • If NP found in direct searches at LHC, B (as well as D, K) physics measurements will help understanding its nature and flavour structure • this workshop to explore such complementarity

  23. PYTHIA+GEANT full simulation RICH1 VELO TT Magnet MC truth Reconstructed MC truth RICH2 T1 T2 T3 100 mm 10 mm Expected LHCb tracking performance • High multiplicity environment: • In a bb event, ~30 charged particles traverse the whole spectrometer • Full pattern recognition implemented: • Track finding efficiency > 95% for long tracks from B decays(only 4% ghosts for pT > 0.5 GeV/c) • KS+– reconstruction 75% efficient for decay in the VELO, lower otherwise

  24. BsDs proper time resolution st ~ 40 fs Expected tracking performance • Mass resolutions in MeV/c2 • Proper time resolution: ATLAS: t~ 100 fs (was 70 fs) CMS: t~ 100 fs LHCb: t~ 40 fs without J/ mass constraint with J/ mass constraint Good proper time resolution essential for time-dependent Bs measurements !

  25. S/B ~ 3 (derived from 107 fully simulated inclusive bb events) LHCb  5 observation of Bs oscillationsfor ms < 68 ps–1 with 2 fb–1 Bs oscillations • Measurement of ms is one of the first LHCb physics goals • Expect 80k Bs Ds-p+ events per year (2 fb–1), average t ~ 40 fs Distribution of unmixed sample after 1 year (2 fb–1) assuming ms = 20 ps-1

  26. Bs oscillations • Current SM expectation of ms(UTFit collab.): • LHC reach for 5 observation: ATLAS/CMS 30 fb–1 3 years LHCb 0.25 fb–1 1/8 year

  27. fs and DGs from BsJ/, … • BsJ/ is the Bs counterpart of B0J/ KS: • Bs mixing phase fs is very small in SM:fs = –arg(Vts2)=–22 ~ –0.04  sensitive probe for new physics • J/ final state contains two vectors: • Angular analysis needed to separate CP-even and CP-odd • Fit for sin fs, DGs and CP-odd fraction (needs external ms) • Sensitivity (at ms = 20 ps–1): • LHCb: • 125k BsJ/ signal events/year (before tagging), S/Bbb > 3stat(sin s) ~ 0.031, stat(s/s) ~ 0.011 (1 year, 2 fb–1) • can also add pure CP modes such as J/, J/’, c (small improvement)stat(sin s) ~ 0.013 (first 5 years)  will eventually cover down to ~SM • ATLAS: • similar signal rate as LHCb, but stat(sin s)~ 0.14 (1 year, 10 fb–1) • CMS: • > 50k events/year, sensitivity study in progress

  28. ^ AFB(s) for b+– ATLAS expectation for 30 fb–1 SM MSSM C7eff>0 ^ s = (m/mb)2 Exclusive b  s+- AFB(s) for B0K*0 • Suppressed decays, SM BR ~ 10–6 • Forward-backward asymmetry AFB(s) in the  rest-frame is sensitive probe of New Physics: • Zero can be predicted at LO with no hadronic uncertainties, depends on Wilson coefficients s = (m)2 [GeV2] • LHCb: • 4400 B0 K*0m+m- events/2fb–1, S/B > 0.4 • After 5 years: zero of AFB(s) located to ±0.53 GeV2 determine C7eff/C9eff with 13% error (SM) • ATLAS: • 1000 B0 K*0m+m- events/10fb–1, S/B > 1 • Other exclusive bs feasible (Bs, b)

  29. Bs +– • Very rare decay, sensitive to new physics: • BR ~ 3.5  10–9 in SM, can be strongly enhanced in SUSY • Current limit from Tevatron (CDF+D0): 1.5  10–7 at 95% CL • LHC should have prospect for significant measurement, but difficult to get reliable estimate of expected background: • LHCb: Full simulation: 10M inclusive bb events + 10M b, b events (all rejected) • ATLAS: 80k bb events with generator cuts, efficiency assuming cut factorization • CMS: 10k b, b events with generator cuts, trigger simulated at generator level, efficiency assuming cut factorization • New assessment of ATLAS/CMS reach at 1034 cm–2s–1 in progress

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