R ECENT RESULTS FROM LHCb A BRIEF SELECTION Patrick Spradlin on behalf of the LHCb collaboration University of Glasgow Particle Physics Fourth workshop on flavour symmetries and consequences in accelerators and cosmology (FLASY 2014) 17-21 June 2014, University of Sussex, Brighton, UK P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 1 / 24
LHCb at the LHC L ARGE H ADRON C OLLIDER P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 2 / 24
LHCb at the LHC F ORWARD ACCEPTANCE Forward acceptance 2 < η < 5. 8 2 Takes advantage of the η LHCb acceptance predominant forward production of 6 GPD acceptance heavy flavored hadrons. 4 2 b 0 θ 1 z θ -2 2 b -4 LHCb MC LHCb MC -6 s = 7 TeV s = 7 TeV -8 -8 -6 -4 -2 0 2 4 6 8 η 1 0 Pseudorapidity range unique π /4 π 0 among the LHC detectors. θ /2 [rad] π /4 2 π π 3 /4 /2 π 3 /4 θ π π [rad] Complementary to the GPDs. 1 P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 3 / 24
LHCb at the LHC LHCb detector P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 4 / 24
LHCb at the LHC LHCb beyond design Exceeding design specifications to maximize physics reach Design 2012 Instantaneous luminosity, L inst ( cm − 2 s − 1 ) 2 × 10 32 4 × 10 32 Mean visible p - p interactions/crossing, µ 0 . 4 1 . 6 HLT output rate to tape ( kHz ) 2 5 High rate heavy flavor production into 1 Probability LHCb acceptance: 0.9 Design Operation 0 0.8 σ vis pp = 58 . 8 ± 0 . 2 mb 0.7 [JINST 7 (2012) P01010] 0.6 0.5 σ bb , acc = 75 . 3 ± 14 . 1 µ b 1 0.4 [PLB 694 209-216] 2 0.3 3 4 ⇒ 30 kHz of bb production. 5 0.2 0.1 σ cc , acc = 1419 ± 134 µ b 0 32 33 10 10 [Nucl.Phys.B 871, 1-20] Luminosity [cm -2 s -1 ] ⇒ 600 kHz of cc production. P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 5 / 24
LHCb at the LHC T RIGGER STRUCTURE Architecture and performance 40 MHz bunch crossing rate documented in JINST 8 (2013) P04022. Input includes 15 MHz of non-empty bunch L0 Hardware Trigger : 1 MHz crossings. readout, high E T /P T signatures L0 hardware trigger includes three main 450 kHz 400 kHz 150 kHz h ± µ/µµ e/ ! collections of channels Hadron calorimeter triggers, Software High Level Trigger Muon detector triggers, 29000 Logical CPU cores Offline reconstruction tuned to trigger Electromagnetic calorimeter triggers. time constraints Mixture of exclusive and inclusive HLT software trigger divided into two selection algorithms sequential stages 5 kHZ Rate to storage HLT1: high- p T displaced tracks, 2 kHz 2 kHz 1 kHz Inclusive/ 70 kHz retention. Inclusive Muon and Exclusive Topological DiMuon Charm HLT2: full event reconstruction P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 6 / 24
LHCb at the LHC LHCb data collection 2010-2013 Data collection with pp collisions: Data collection with p Pb collisions: 2010 38 pb − 1 √ s = 7 TeV , 2013 1.9 nb − 1 √ s NN = 5 TeV . 2011 1.1 fb − 1 √ s = 7 TeV , 2012 2.0 fb − 1 √ s = 8 TeV . P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 7 / 24
LHCb at the LHC LHCb physics program I LHCb is designed for high precision searches for indirect evidence of New Physics beyond the Standard Model in Heavy meson mixing, e.g. , φ s in B 0 s mixing, A Γ in D 0 - D 0 mixing. CP violation, e.g. , γ ( φ 3 ) in B decays, Direct CP violation in B and D decays. Rare transitions of of b (and c ) hadrons, e.g. , Branching fractions of rare decays like B ( s ) → µ + µ − , A FB and angular analysis of B 0 → K ∗ 0 µ + µ − and related modes. In these tasks, LHCb is performing admirably. P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 8 / 24
LHCb at the LHC LHCb physics program II However, it is also an ideal laboratory for a much broader physics program, including Spectroscopy and the discovery of new states, Precision mass and lifetime measurements, Production measurements and precision tests of QCD, Precision branching fraction and decay amplitude measurements, including newly observed decay modes, Studies of proton–ion collisions at forward rapidities. Almost 200 papers submitted to journals This talk includes just a small selection of recent results P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 9 / 24
Z ( 4430 ) + Z ( 4430 ) − IN B 0 → ψ ′ π − K + PRL 112 222002 (2014) Four-dimensional amplitude analysis of B 0 → ψ ′ ( µ + µ − ) π − K + ) 2 1000 Candidates / ( 0.2 GeV LHCb m 2 ( K + π − ) , m 2 ( ψ ′ π − ) , ψ ′ helicity angle cos θ ψ ′ , 500 and decay plane angle φ . 25176 ± 174 B 0 → ψ ′ ( µ + µ − ) π − K + decays 0 16 18 20 22 2 m 2 [GeV ] An order of magnitude more than − ψ π ' previous analyses. ) 2 Candidates / ( 0.02 GeV 3 10 LHCb Z ( 4430 ) − established at 13 . 9 σ with properties 2 10 m ( Z ) = 4475 ± 7 + 15 − 25 MeV , 10 Γ( Z ) = 172 ± 13 + 37 − 34 MeV , 1 f Z = ( 5 . 9 ± 0 . 9 1 . 5 3 . 3 )% , 0.5 1 1.5 2 2.5 2 J P = 1 + , with other assignments ruled m 2 [GeV ] π − + K out at > 9 σ . P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 10 / 24
Z ( 4430 ) + Z ( 4430 ) − IN B 0 → ψ ′ π − K + PRL 112 222002 (2014) Model-independent analysis: Efficiency corrected yield / ( 25 MeV ) 0.04 LHCb Method of BaBar, PRD 79 112001 (2009) 0.03 Legendre moments of K ∗ helicity angle distribution in slices of m ( K + π − ) , 0.02 Reflect J ≤ 2 moments into the 0.01 m ( ψ ′ π − ) distribution. 0 K ∗ reflections unable describe the data. 3.8 4 4.2 4.4 4.6 4.8 m [GeV] ψ π − ' − Z Im A LHCb Replace Breit-Wigner amplitude model for 0.2 Z ( 4430 ) − with six independent complex amplitudes in bins of m ( ψ ′ π − ) in the peak region, 0 Tests phase variation with mass, -0.2 Argand diagram shows rapid variation of -0.4 phase at peak of magnitude, -0.6 Consistent with resonance. -0.6 -0.4 -0.2 0 0.2 − Z Re A P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 11 / 24
P IN D 0 → h − h + DECAYS A C A CP IN D 0 → h − h + DECAYS LHCb-PAPER-2014-013, ACCEPTED BY JHEP 3 × 10 ) Samples of D 0 → K − K + and D 0 → π − π + 160 2 LHCb c Candidates / ( 1.1 MeV/ 140 Data produced in B → D 0 µ − ν µ X 120 Total Signal 100 Charge of muon tags initial flavor of D 0 . Comb. bkg. 80 60 40 Observed asymmetries a combination of CP 20 asymmetry and confounding detection and 0 1850 1900 production asymmetries. . . − + M(K K ) [MeV/ c 2 ] ∼ 2 million D 0 → K − K + decays A raw = A CP + A D ( µ − ) + A P ( B ) Full 3 fb − 1 Run 1 sample . . . that cancel in the difference ∆ A CP ≡ A CP ( K − K + ) − A CP ( π − π + ) = A raw ( K − K + ) − A raw ( π − π + ) Further, A CP ( K − K + ) can be extracted directly B → D 0 ( K − π + ) µ − ν µ X decays to cancel A D ( µ − ) + A P ( B ) , Samples of promptly produced D + → K − π + π + and D + → K 0 π + to measure the K − π + detection asymmetry in the D 0 → K − π + sample A CP ( K − K + ) = A raw ( K − K + ) − A raw ( K − π + ) + A D ( K − π + ) P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 12 / 24
P IN D 0 → h − h + DECAYS A C A CP IN D 0 → h − h + DECAYS LHCb-PAPER-2014-013, ACCEPTED BY JHEP A CP has contributions from direct and indirect 3 10 × ) 2 60 LHCb c CP violation. Candidates / ( 1.45 MeV/ Data 50 Total Indirect contribution dependent on mean D 0 40 Signal Comb. bkg. decay time of sample. 30 0 − + D K → π 20 � t � A CP ≈ a dir CP − A Γ 10 τ 0 1800 1850 1900 τ similar for K − K + and π − π + samples � t � − + [MeV/ 2 ] M( π π ) c ∼ 0 . 8 million D 0 → π − π + decays ⇒ ∆ A CP ≈ ∆ a dir Full 3 fb − 1 Run 1 sample CP The most precise measurements of time-integrated CP asymmetries in D 0 → h − h + decays from a single experiment to date: ∆ A CP = (+ 0 . 14 ± 0 . 16 ± 0 . 08 ) % A CP ( K − K + ) = ( − 0 . 06 ± 0 . 15 ± 0 . 10 ) % A CP ( π − π + ) = ( − 0 . 20 ± 0 . 19 ± 0 . 10 ) % P. S PRADLIN (G LASGOW ) R ECENT RESULTS FROM LHCb FLASY 2014.06.19 13 / 24
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