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LHCb impact on CKM fits

This talk discusses the impact of the LHCb experiment on CKM fits and the baseline luminosity program. It covers the startup of the LHC, calibration of detectors, and the delivery of integrated luminosity in subsequent years. It also discusses the prospects of lattice QCD and the future projections for B-physics measurements.

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LHCb impact on CKM fits

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  1. BOLOGNA LHCb impact on CKM fits Vincenzo Vagnoni(for the LHCb Collaboration) Nagoya, Thursday 14th December 2006

  2. LHCb startup and baseline luminosity programme • Startup of LHC beam in 2007 • Pilot run at 450 GeV per beam with full detector installed • Establish running procedures • Time and space alignment of the detectors, calibrations • 2008: LHC ramps up to 7 TeV per beam • Complete commissioning of detector and trigger at 14 TeV • Including calibration of momentum, energy and particle ID • Start of first physics data taking • Baseline LHCb luminosity programme • Integrated luminosity of ~0.5 fb-1 delivered in 2008, ~2 fb-1 in subsequent years • physics results with 2 fb-1 available in 2010, 10 fb-1 available in 2014 • Ongoing discussion for an upgrade beyond 2014: Super-LHCb • Note: instantaneous luminosity at the LHCb IP of 2·1032 cm-2 s-1 is almost two orders of magnitude below the LHC challenges* • Thus we expect the LHCb luminosity requirements can be fulfilled very early in the LHC operation * the B-physics reach of Atlas and CMS will not be considered in this talk

  3. Lattice QCD prospects • To exploit precision measurements where hadronic parameters play a role, a substantial improvement should be achieved during the following decade Uncertainties in LQCD calculation dominated by systematic errors, overall accuracy does not improve according to simple scaling laws Disclaimer: estimates on a 10 years scale very difficult... to be taken cum grano salis 6 TFlop year and 10 TFlop year predictions fromS. Sharpe @ Lattice QCD: Present and Future, Orsay, 2004 and report of the U.S. Lattice QCD Executive CommitteeProjections to far future from V. Lubicz @ SuperB IV Workshop * no improvements on Vub- and Vcb-inclusive determinations assumed

  4. Where will we be at the end of theB-factories and the Tevatron?(i.e. before LHCb data) (I) • Bd/B+ sector: B-factories • Assume an integrated luminosity of 2 ab-1 at the (4S) provided by BaBar and Belle together, and... • ()  6.5° • From Bpp, Brr SU(2) analyses, and B(rp)o time dependent Dalitz • ()  6.5° • From BDK, GLW, ADS and Dalitz analyses • Assuming significant reduction of the systematics, in particular improvements in the knowledge of the D decay model, e.g. using CLEO-c data and/or model independent fits on the Dalitz plane • (sin2)  0.017 • Bs sector: Tevatron • Assume (2x) 6 fb-1 collected by CDF and D0, and... • (s)  0.2 • (s/s)  0.04 • (ms)  0.5% First direct measurement of sfrom D0 available: s= -0.79 ± 0.56 ± 0.01(see talk by B. Casey)

  5. Where will we be at the end of theB-factories and the Tevatron?(i.e. before LHCb data) (II) • Nice improvement in 2008, in particular for r • mostly due tobetter  and LQCD * Every projection to the future shown in this talk has been obtained by fine-tuning the central values of future measurements around Standard Model expectations, i.e. no New Physics assumed ! Summer 2006 2008*

  6. LHCb impact with first year physics data (int. L=0.5fb-1) (I) • Data taking in 2008 will be crucial to understand detector and trigger performance and assess the LHCb potential • Can use well established measurements from the B-factories and the Tevatron to “calibrate” our CP sensitivity • B-factory sin2 (final sensitivity ~0.017) vs LHCb-2008 J/KSsin2 (~0.04) • Will demonstrate with already considerable precision that we can keep under control the main ingredients of CP-analyses, e.g. opposite side tagging • Tevatron ms (final sensitivity ~0.09 ps-1) vs LHCb-2008(~0.014 ps-1, stat. only) • Hadronic trigger, control of proper time resolution, same side K tagging, etc.

  7. LHCb impact with first year physics data (int. L=0.5fb-1) (II) • Perform the first high precision measurement of s • Tevatron s (final sensitivity ~0.2) vs LHCb-2008 (~0.04) • Could make a 5 discovery of New Physics effects in the Bs mixing phase with the first year of data if NP s is O(10°) • Bring down the limit of BR(Bsmm) • Other big milestone in the search for New Physics (see talk by J. Dickens) • Potential to exclude BR between 10-8 and SM value with the first year only ! • Other relevant measurements • e.g. b-hadron lifetimes, Bh+h-’ (see J. Nardulli), ... • First results with “more difficult” measurements... get a taste of! • e.g. Dalitz analyses of BDK and B(rp)o

  8. now s(sin2b) pre-LHCb with LHCb at L=10fb-1 with LHCbat L=2fb-1 year sin2 from BdJ/KS • The golden mode at B-factories, already well known, but still relevant to improve the measurement In one LHCb year (L=2fb-1) Yield:~216k BdJ/(mm)KSevents with B/S0.8 Sensitivity:s(sin2b) = 0.02 background subtractedCP asymmetry with L=2fb-1 Overall improvement by roughly a factor 2 with LHCb at L=10 fb-1

  9. s(s) s(s) LHCb atL=2fb-1 now now pre-LHCb LHCb at L=10fb-1 pre-LHCb LHCb at L=10fb-1 LHCb atL=2fb-1 year year s and s at LHCb • BsJ/ is the el-dorado mode at LHCb • counterpart of BdJ/KS for measuring the Bs mixing phase, but also other modes contribute • Signal yield: 130k events per L=2fb-1 with a B/S0.1 • very sensitive probe of New Physics effects in the Bs mixing • s = s(SM) + s(NP) • s(SM)=-2l2h, small and very well known from indirect UT fits: -0.037±0.002 • slight complication: 2 CP-even and 1 CP-odd amplitudes, angular analysis is needed to separate the states s poorly known now, but willbe known as well as sin2b thanks to LHCb SeeJ. van Hunen’s talk

  10. LHCb Bd(rp)o only s() [o] now pre-LHCb with LHCb at L=10fb-1 with LHCbat L=2fb-1 year Sensitivity to  •  more challenging for LHCb, due tothe need of reconstructing o’s inhadronic environment • 2 analyses under study • Time-dependent Bd(rp)o Dalitz plot  • with L=2 fb-1 LHCb estimates a sensitivity σ10° • Brr SU(2) analysis • Very preliminary studies indicate the need of a few years of LHCb running to improve the current Bdr+r- measurement. • With 2 fb-1the main LHCb contribution will be most likely the improved measurement ofBdroro (fully charged final state) • Need more time and refined studiesto give firm results for  • In the following we will conservativelyassume to measure alpha with theBd(rp)o mode only r+p- r0p0 N3π = 14k events / 2 fb-1, B/S~1 r-p+

  11. m- LHCb simulation r(770) s(g) [o] now K* and DCS K* pre-LHCb with LHCbat L=2fb-1 with LHCb at L=10fb-1 m+ year Sensitivity to  • Several modes to measure  at LHCb • ADS+GLW • Dalitz analysis with D3-body • “Dalitz” analysis with D4-body • Golden BsDsK mode • Sensitivity estimated at ~4.2° with L=2fb-1 • Assuming the same improvements of the Dalitz syst. error as for the projections of the B-factories to 2008 By 2014 sensitivity at about 2 degrees See M. Patel’s talk

  12. Unitarity Triangle prospectsfrom LHCb only 2010 2014 LHCb L=2 fb-1 LHCb L=10 fb-1 Using , ,  and Dms from LHCb only • + theory for Dmd/Dms • Not employing the full LHCb potential for  in this study • Somewhat conservative: just  from (rp)o

  13. Unitarity Triangle in 2014 Without LHCb With LHCb at L=10fb-1

  14. For the neutral kaon mixing case, it isconvenient to introduce only one parameter Allowing for New Physicsin the mixing The mixing processes being characterized by a single amplitude, they can be parametrized in a general way by means of two parameters • HSMeff includes only SM box diagrams while Hfulleffincludes New Physics contributions as well Summer 2006 (r, h)with NPallowed Four “independent” observables • CBd, Bd, CBs, Bs • CBq=1, Bq=0 in SM Using Tree-level processes assumed to be NP-free *the effect in the D0-D0 mixing is neglected 5 additional parameters

  15. The r-h plane in 2014 allowing for NP in the mixing Without LHCb With LHCb at L=10 fb-1 • By allowing for arbitrary NP contributions in the mixing, the UT apex will be basically determined by the Tree-level constraints, and it will be the reference for any NP model building • caveat: neglecting here NP effects in neutral D-meson mixing • LHCb will further constrain the apex, due to substantial improvement in the  measurement

  16. Measuring New Physics in the Bs mixing End of Tevatron • Dramatic impact of LHCb on the Bs mixing phase • can bring down the sensitivity to the NP contribution Bs from 5.6° at the end of the Tevatron to 0.3° • NP in the Bs mixing will be known three times better than in the Bd by 2014 • without the need of improvements from theory With LHCb atL=10 fb-1 in 2014 As far as CBd and CBs are concerned, they are dominated by theory  no great impact from LHCb measurements(CBs)~0.06(CBd)~0.09

  17. Interpretation of s vs sin2 • Most precise measurements today available are Dmd/Dms, sin2b and |Vub/Vcb| • A disagreement between Dmd/Dms and g would spot out NP in the magnitude of the mixing amplitudes • But uncertainty on  still too large • To find evidence of NP effects in the Bd mixing phase, it is instead important to compare sin2b with |Vub/Vcb| • but need to heavily rely on Lattice QCD, interpretation in case of slight disagreement not trivial Example: current UT fits show slight disagreement between sin2b and |Vub/Vcb|, due to excess ofVub-inclusive / defect of sin2b(JHEP 0610 (2006) 081) First NP hint or theory problem in Vub? No such interpretation problems for s,just go and measure it !If different from -0.037±0.002, NP is there

  18. Conclusions • LHCb will improve the knowledge of the Unitarity Triangle • in particular due to increased precision on the measurement of  and, and maybe to a lesser extent of  • both in Standard Model and (even more) in NP allowed scenarios • LHCb will measure the Bs mixing phase with ultimate precision • Impressive improvement of a factor 20 since the end of Tevatron data taking • NP angle Bs will be known at 5.6° from the Tevatron, and 0.3° at LHCb (with int. L=10fb-1) ! • Much easier intepretation than sin2b, NP might show up very early just with the first year of data in 2008 • After “LHCb phase I”, in 2014, NP in the Bs mixing will be more constrained than in the Bd • Other big milestones from LHCb, not impacting on CKM fits or not considered in this talk • Radiative and rare decays • BdK*g, Bsfg, BdK*mm, Bsmm • bsss penguins • e.g. Bsff • Bhh’ • Charm physics, ...

  19. Backup

  20. b b PT of B-hadron 100μb ~1 cm 230μb Pythia B η of B-hadron The LHC beauty experiment Forward-backward correlation of bb angular distribution - Single-arm forward spectrometer, acceptance: 15-300 mrad b Tracking: Vertex Locator, TT, T1, T2, T3 PID: 2 RICH detectors, SPD/PS, ECAL, HCAL, Muon stations b Interaction point pp at 14 TeV “b-factory” Luminosity at IP8 = 2·1032 cm-2s-1 1012 bb produced per year including all b-hadrons species

  21. LHCb Calorimeter • 4 devices: Scintillator Pad Detector (SPD), Preshower (PRS), Electromagnetic Calorimeter (ECAL) and Hadronic Calorimeter (HCAL). • Provides with acceptance 30 mrad to 300 (250) mrad: • Level-0 trigger information (high transverse momentum hadrons, electrons, photons and p0, and multiplicity) • Kinematic measurements for g and p0 with sE/E = • Particle ID information for e, g, and p0. 10%  1% E

  22. e Merged Resolved Transverse energy (GeV) p0 reconstruction at LHCb • Resolved p0: reconstructed from 2 isolated photons • sm = 10 MeV/c2 • Merged p0: pair of photons from high energy pion which forms a single ECAL cluster, where the 2 showers are merged. • The pair is reconstructed with a specific algorithm based on the expected shower shape. • sm = 15 MeV/c2 • Reconstruction efficiency: ep0 = 53 % for B0p+p-p0 Resolved π0 Merged π0 π0 mass (Mev/c²)

  23. K- s l W b c Vcb B- u c u u u Vub = |Vub | e-ig u D 0 b B- W s K- u Tree level determination of  from B±D(*)0K(*)± Interference if same D0 and D0 final states Favoured GLW (Gronau,London,Wyler) Uses CP eigenstates of D0 decays D0 ADS (Atwood, Dunietz, Soni) Colour suppressed Dalitz Method – GGSZanalyze D0 three-body decayson the Dalitz plane strong amplitude (the same for Vub and Vcb mediated transitions Break-through ofB-factories, but statistically limited and extremely challenging! strong phase difference between Vub and Vcb mediated transitions rB is a crucial parameter - the sensitivity on depends on it

  24. Bounds on NP size and phase Bs Bd dark: 68% light: 95% dark: 68% light: 95% The allowed NP amplitude is still large for small phase shift MFV scenarios are strongly favored at this point, but we still might see a large NP phase in Bs mixing

  25. Minimal Flavour Violation: the only source of flavour violation is in the SM Yukawa couplings (implies =0) New Physics couplings between third and second families (bs sector) stronger with respect to the bd ones Flavour physics needs to improve existing measurements in the Bd sector and perform precise measurement in the Bs sector (mixing phase still largely unknown) MFV or not MFV? New Physics in the bd and recently in bs sector startsto be quite constrained and most probably will not come as an alternative to the CKM picture, but rather as a «correction»

  26. LHCb sensitivity: summary

  27. Perspectives up to 2014 Pre-LHCb: B-factories and Tevatron at end of their life, 2008-2009

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