1.LHCb status 2.Physics highlights 3.Plans Roger Forty (CERN) on behalf of the LHCb Collaboration Physics at the LHC, Vancouver, 49 June 2012 LHCb status and plans LHCb is the dedicated flavour physics experiment at the LHC ATLAS & CMS search for the direct production of new states LHCb is designed to see their indirect effect on charm and beauty decays via virtual production in loop diagrams: Such an indirect approach can be very powerful: e.g. B 0 B 0 mixing discovered at ARGUS (1987) top quark unexpectedly heavy: m(t) > 50 GeV/c 2 Key topics for LHCb include: to check whether CP violation is due to a single phase in the quark mixing (CKM) matrix, as in the Standard Model Study rare decays: FCNC decays (e.g. B s ) are strongly suppressed in SM, may be enhanced by Supersymmetry, or other new physics Roger FortyLHCb status and plans1 1. LHCb status e e (4S) B 0 B 0 Roger FortyLHCb status and plans2 Forward spectrometer p p 10 300 mrad [PYTHIA] [CONF ] Marco Adinolfi See talk of Forward-peaked B production LHCb is a forward spectrometer (operating in collider mode) bb cross-section = 284 53 b at the LHC ( s = 7 TeV) [PLB ] ~ 100,000 bb pairs produced/second (10 4 B factories) Charm production factor ~20 higher! Advantages Roger FortyLHCb status and plans3 [arXiv: ] b*b* Bc+Bc+ [arXiv: ] B+ ++B+ ++ [CONF ] [CONF ] ATLAS/CMS LHCb W charge asymmetry vs William Barter & Marianna Fontana Enormous production rate have overtaken B factories even for B 0 and B + decays BR (B + (2.4 0.6 stat 0.2 sys ) 10 -8 Previous limit < 6.9 ( Belle PRD ) Rarest B decay ever observed! All b-hadron species are produced at the high energy of the LHC New states discovered e.g. b * (5912/5920) orbitally-excited states New decay modes discovered e.g. B c + J/ + + B s physics is rich and little explored Large boost: B decay lengths ~ O (1 cm) Complementary coverage for other physics Electroweak, QCD, exotics, Roger FortyLHCb status and plans4 Collaboration Added since PLHC-2011: Birmingham, Cincinnati, Lahore, Rostock VELO Magnet Muon detector Calorimeters RICH Tracker 16 Dipole magnet, polarity regularly switched to cancel systematic effects New this year: beam optics changed to decouple crossing angles from LHC (V) and spectrometer magnet (H) Momentum resolution: p/p = 0.4 0.6 % (5100 GeV/c) Tracking performance Roger FortyLHCb status and plans5 B s J/ Beam optics at interaction point (m B ) = 8 MeV/c 2 cf ~ 16 MeV/c 2 [CMS DPS ] 22 MeV/c 2 [ATLAS CONF ] [CONF ] Real data! Roger FortyLHCb status and plans6 Vertex detection [CONF ] Prompt J/ B s J/ Beam r z VELO (Vertex Locator) 21 modules of r- silicon sensor disks Retracted for safety during beam injection Reconstructed beam-gas vertices (used for luminosity measurement) Impact parameter resolution ~ 20 m Proper-time resolution: t = 45 fs cf CDF: t = 87 fs [PRL ] VELO sensors 7 mm [PLB ] Beam 2 Beam 1 RICH-1: dual radiator Roger FortyLHCb status and plans7 Particle identification Charged hadrons identified with two Ring-imaging Cherenkov detectors covering 2 < p < 100 GeV/c Hybrid Photon Detectors (HPDs) 500 tubes each with 1024 pixels High efficiency, low noise New this year: gas-tight box for aerogel to avoid contamination by C 4 F 10 gas K K > 90% for K < 5% Allows strong suppression of combinatorial background in hadronic decays e.g. K K RICH-1: dual radiator Without RICH With RICH Roger FortyLHCb status and plans8 Calorimeters + Muon ECAL: Shashlik Pb-scintillator (E)/E = 10% /E 1% HCAL: Tile Fe-scintillator allows triggering on hadronic final states Muon system: 5 stations MWPCs/Fe [arXiv: ] Giacomo Graziani [arXiv: ] s Nominal LHCb luminosity = 2 cm -2 s -1 Precision physics depending on vertex structure: easier in a low-pileup environment Continuous (automatic) adjustment of offset of colliding beams allows luminosity to be levelled Thanks to LHC team for excellent collaboration! Data taken with high efficiency > 90% Offline data quality rejects 98% active channels Roger FortyLHCb status and plans9 Data taking LHCb pp collisions/crossing (25ns) 2011 was a fantastic year! L dt = 1 fb -1 (used for most results shown here) ~ 30 more data than at PLHC-2011 Data taking in 2012 at 4 cm -2 s -1 ~ 0.4 fb -1 integrated so far Trigger in two steps: Level-0 in hardware p T of e, , and hadron (thresholds ~ 13 GeV) reduce rate to 1 MHz Then all detectors read out into large CPU farm (~1500 servers) High Level Trigger in software New this year: Output rate increased to 4.5 kHz to provide data sample for analysis during shutdown (events are relatively small ~ 60 kB) Deferred triggering: fraction of events written to local storage of CPUs and processed during inter-fill gap ~10% increase in effective power O(10 10 ) events recorded per year: centralized stripping selection to reduce to samples of < ~10 7 events for individual analysis: ~ 800 selections! Roger FortyLHCb status and plans10 Data processing 4.5 kHz Storage Detector Output rate of single server vs time 2. Physics highlights Roger FortyLHCb status and plans11 Miriam Calvo Gomez 56 physics publications to date, more in pipeline > 80 preliminary results submitted as Conference Papers [LHCb-CONF-xxx] all available atCan only give a selective taste of LHCbs physics output for the full feast see the contributed talks and posters Tagging of production flavour (B/B) important for mixing & CP analyses Performance calibrated using control channels such as B + J/ K + Tagging power: eff = (1 w) 2 determined from mixing signals eff = (3.2 0.8) % (Opposite side) (1.3 0.4) % (Same side) [CONF ] Right-sign Roger FortyLHCb status and plans12 Particle-antiparticle mixing B0B0 D0D0 Wrong-sign Bs0Bs0 [CONF ] [arXiv: ] [CONF ] B 0 D * + Studied for all neutral mesons B 0 : now well-established B s 0 : studied using B s 0 D s + decays m s = ps -1 (world-best) cf : 0.10 0.07 ps -1 (CDF PRL ) D 0 : wrong-sign decays D 0 K + measured Time-dependent analysis in progress to separate mixing from DCS contribution Phase of B 0 mixing is well known: sin 2 = 0.67 0.02 [PDG] Analogous phase in the B s system is denoted s Expected to be very small, precisely predicted: s = rad (SM) First Tevatron results hinted at large value (discrepancy with SM up to ~3 Golden mode for this study is B s J/ VV final state: mixture of CP-odd and -even components separated using angular analysis Roger FortyLHCb status and plans13 CP violation [ LHCb-CONF ] Olivier Leroy Transversity angle distributions [CONF ] CP-even CP-odd [arXiv: ] Roger FortyLHCb status and plans14 Results correlated with s = width difference of the B s mass-eigenstates plotted as contours in ( s vs s ) plane Ambiguous solution excluded by study of phase vs KK mass CPV in B s mixing Sean Benson [CONF ] SM Result presented at PLHC-2011 [arXiv: ] Update with 10 data LHCb result consistent with Standard Model First significant direct measurement of s = ps -1 s also measured in a second mode: B s J/ f 0 Combined result: s = rad Still room for new physics: increased precision required! Roger FortyLHCb status and plans 15 CPV in B decays [PRL ] B 0 K B 0 K Daniel Johnson Using the particle ID capability of LHCb, can isolate clean samples of the various decays that contribute to 2-body B h h h p B 0 : direct CP violation (in decay) clearly visible in raw distributions Corrections required for detector and production asymmetries controlled using D 0 , B 0 J/ K *0 samples: percent-level effects A CP = (B 0 K ) (B 0 K ) / sum = in good agreement with world average: B s K B s K Adjusting the selection to enhance the B s K contribution A CP (B s K ) = 0.27 0.08 0.02 First 3 evidence for CP asymmetry in B s decays B s strongly suppressed in SM Predicted BR = (3.2 0.2) 10 9 * very sensitive to new physics Analysis based on multivariate estimator (BDT, combining vertex and geometrical information) & dimuon mass M Their distributions calibrated using data: B hh and dimuon resonances World-best limit set: BR < 4.5 (at 95% CL) cf < 7.7 (CMS arXiv: ) < 22 (ATLAS CONF ) Sensitivity (slightly) greater than CMS from 5 less integrated luminosity * Experimental BR is time-integrated, so prediction should be scaled by 1.1 for comparison [arXiv: ] Roger FortyLHCb status and plans16 M in sensitive region of BDT Rare decays [arXiv: ] Setting limit on BR Mitesh Patel Cosme Adrover [JHEP ] B s candidate m = GeV, BDT = 0.90, Decay length = 11.5 mm Tracks shown for p T > 0.5 GeV Roger FortyLHCb status and plans17 M in sensitive region of BDT Rare decays [arXiv: ] Setting limit on BR Mitesh Patel Cosme Adrover B s strongly suppressed in SM Predicted BR = (3.2 0.2) 10 9 * very sensitive to new physics Analysis based on multivariate estimator (BDT, combining vertex and geometrical information) & dimuon mass M Not enough candidates to provide significant measurement of BR World-best limit set: BR < 4.5 (at 95% CL) cf < 7.7 (CMS arXiv: ) < 22 (ATLAS CONF ) Large enhancement of BR relative to SM expectation is ruled out * Experimental BR is time-integrated, so prediction should be scaled by 1.1 for comparison [arXiv: ] [JHEP ] [CONF ] SM [arXiv: ] Roger FortyLHCb status and plans18 B0 K*B0 K* Cosme Adrover 1.3 Rare decay via b s penguin: Forward-backward asymmetry sensitive to modification of the helicity structure Previous results hinted at discrepancy LHCb has largest sample in the world: 900 events, as clean as the B factories! Zero-crossing point precisely predicted q 2 (A FB = 0) = 4.0 4.3 GeV 2 /c 4 First measurement: GeV 2 /c 4 Earlier discrepancies not confirmed However, evidence seen for different BR between B K & B 0 modes ( Additional slides) LHCb results provide strong constraints on possible models for new physics Complementary to the direct searches at ATLAS/CMS Recent examples: limit on B s constraining SUSY at high tan and combination of B s and s restricting various models: Roger FortyLHCb status and plans19 [D. Straub, arXiv: ][N. Mahmoudi, Moriond QCD] Impact of results And then something unexpected ss Direct exclusion (CMS 4.4 fb -1 ) B s (LHCb 1 fb -1 ) Roger FortyLHCb status and plans20 CPV of charm Silvia Borghi [PRL ] D 0 K + K 1.4 10 6 signal LHCb Expected to be small in the SM (< ) Enormous statistics available: > 10 6 D 0 K + K from D *+ D 0 + Charge of from D * determines D 0 /D 0 A CP = difference in CP asymmetry for D 0 K + K and D 0 Robust: detection and production asymmetries cancel (at first order) A CP = ( 0.82 0.21 0.11)% Zero CPV is excluded at 3.5 Before the LHCb result: CP violation at the percent level signals new physics [Y. Grossman, arXiv:hep-ph/ ] (and many others) After: We have shown that it is plausible that the SM accounts for the measured value Nevertheless, new physics could be at play [J.Brod et al, arXiv: ] New physics has not yet shown itself clearly at the LHC Essential to improve measurements of precisely-predicted quantities: s, BR(B s ), q 2 (A FB = 0) Another example: the CP-angle is the least well measured UT angle (depends on rare b u decays) Uncertainty 1012 [UTfit/CKMfitter] Clean determination using B DK tree decays with theoretical uncertainty < 1 First constraints already achieved: Can profit from much higher statistics long term programme at LHCb 3. Plans Roger FortyLHCb status and plans21 Daniel Johnson & Sean Benson (rad) rBrB [PLB ] Roger FortyLHCb status and plans22 LHCb upgrade Expect to double data-set by end of this year After long shutdown, further doubling of data-set in 201517 (plus increase of cross-sections with higher energy): total of 57 fb -1 Main limitation that currently prevents exploiting higher luminosity is the hardware trigger: keeping output rate < 1 MHz requires raising of thresholds hadronic yields reach plateau: Propose to remove the hardware trigger Read out LHCb at 40 MHz crossing rate Flexible software trigger in CPU farm increase in yields by factor 1020 at 12 cm -2 s -1 (25 ns is required) Requires replacing front-end electronics Planned for the long shutdown in 2018 Running for ~10 years will give 50 fb -1 General-purpose detector for the forward region Silvia Borghi Detector modifications Roger FortyLHCb status and plans23 Baseline detector modifications to allow 40 MHz readout TORCH time-of-flight Pixel VELO e.g. Scintillating-fibre tracker R&D on possible detector upgrades Upgrade status Roger FortyLHCb status and plans24 Letter of Intent for upgrade submitted to LHCC last year Encouraged to proceed to Technical Design Report Framework TDR just submitted (25 May) schedules & cost of subsystems, and institute interests Update of physics case and expected performance: [LHCC ] Timeline (tight!) 2011 Letter of Intent 2012 Framework TDR R&D ongoing 2013 Subsystem TDRs Tender & prod n 2017 Acceptance testing 2018 Installation 2019 Data taking Roger FortyLHCb status and plans25 Conclusions LHCb taking data with high efficiency and excellent detector performance Luminosity above design, 1.4 fb -1 recorded so far Excellent mass and decay-time resolution, particle ID, etc. World-best measurements of many physics parameters m s, s, s, BR(B s ), masses, lifetimes, etc. First observations of new decays, evidence for CP violation of B s So far almost all are in good agreement with the Standard Model strong constraints on new physics in the flavour sector Possible hints of physics beyond the Standard Model require further study: Evidence seen for CP violation in charm, unexpected Isospin asymmetry for B K is also puzzling Upgrade of LHCb in preparation for 2018: 10 yield + software trigger Much more to come: new collaborators welcome! Additional slides Roger FortyLHCb status and plans26 Signal for B 0 K 0 + SM prediction for isospin asymmetry A I of K + [Feldmann &Maas, JHEP ] LHCb result: consistent with SM expectation in this mode [ arXiv: ] A I (%) q 2 (GeV 2 /c 4 ) Compare B 0 K 0 and B + K + decays Isospin asymmetry A I defined as: (B 0 K 0 ) (B + K + ) (B 0 K 0 ) (B + K + ) Expect A I ~ zero in SM (< few %) Results from other experiments tended toward negative values Previous discrepancy with SM is supported by new LHCb result: A I < 0 with over 4 significance No asymmetry seen in closely-related B K * mode (K *+ K 0 + ) No clear interpretation, so far Isospin asymmetry Roger FortyLHCb status and plans27 [arXiv: ] determination Various methods used Inputs mostly from B factories comb = (75.5 10.5) [UTfit] Impact of LHCb results on the combination, for the ADS method (B + D 0 K +, D 0 K + ) [D. Derkach, LHCb-TALK ] Roger FortyLHCb status and plans28 Roger FortyLHCb status and plans29 A SL Strong interest in semileptonic (flavour-specific) asymmetry due to D0 result for dimuon asymmetry (comparing # of and events) A SL = (7.87 1.72 0.93) 10 3 [PRD ] (expect < in SM) Same approach difficult at pp machine due to production asymmetries Instead use semileptonic decays, B (s) D (s) (K K ) X Result from LHCb expected soon Note: if A SL is large, expected to see large s in most models [arXiv: ] Projected LHCb precision (statistical, 1 fb -1 )