Studies of Rare Beauty and Charm Decays with the CMS Experiment

Transcription

1 Studie of Rare eauty and Charm Decay with the CMS Experiment Joe Lazo-Flore (UNL) for the CMS Collaboration SUSY eijing, China Augut 3,

2 Outline The CMS detector Tracking and Muon recontruction -Phyic trigger Rare decay Search for the D μ μ - Search for the (d) μ μ - CMS-PAS-PH-7 JHEP4()33 Augut 3, Joe.Lazo-Flore@cern.ch

3 The CMS Detector General detail Weight 5 ton Length of.6 meter Diameter of 5 meter 3.8T Magnetic Field Sub-detector ued for thi analyi Silicon tracker Si pixel and Si trip Muon ytem Component Detail Reolution Very-forward Calorimeter Pixel (F) 3() Si Layer(Dik) δz μm, δφ μm Tracker (F) () Si Strip δ(pt)/pt % ECal PbWO4 δe/e 3%/ E.5% HCal () ra/sc, > 7.λ δe/e E% HCal (F) Fe/Quartz δ(met).98 ( ET) Magnet 3.8T Solenoid Muon DT/SCS and RPC δ(pt)/pt % (ta) Augut, Hadronic Calorimeter Electromagnetic Calorimeter 3 C ompac t Muon S olenoid Superconducting Solenoid Silicon Tracker Pixel Detector Prehower Muon Detector Joe.Lazo-Flore@cern.ch

4 Tracking and Muon Recontruction Large Acceptance η <.4 Drift tube (DT), cathode drift chamber (CDC), retive plate chamber (RPC) Muon recontruction algorithm Standalone muon: recontructed in muon ytem only Global muon (GM): recontructed outide-in, Standalone muon inner track Tracker muon (TM): recontructed inide-out Augut 3, Inner track muon detector Muon miidentification ε(μ π).% ε(μ K).% ε(μ p).5% Global muon efficiency R (c m) CMS Preliminary, M 4 M 3 M M DT eta =.8.4 ME RPC ME ME 3 CSC Z (c m) arrel! <., 84 nb Simulation = 7 TeV 4 Probe p (GeV/c) T Joe.Lazo-Flore@cern.ch ME 4 CMS-PAS-MUO

5 -Phyic Trigger Total CMS rate of ~ 3 Hz -Phyic rate of a few Hz Ued motly for muon trigger Trigger requirement changed with increaing luminoity Trigger election: η and p requirement for muon Di-muon invariant ma Impact parameter Secondary vertex probability Pointing angle Flight length ignificance Event per MeV Run, L =. fb J/! CMS = 7 TeV!' $ % # trigger path!' J/! - " µ µ # low p double muon T high p double muon T Z dimuon ma [GeV] Augut 3, 5 Joe.Lazo-Flore@cern.ch

6 Search for the D μ μ - decay Motivation: Decay highly uppreed in SM (D μ μ - ) ~ 3 Thi i becaue: FCNC are forbidden at tree level Decay i helicity uppreed by a factor of (m μ/m D ) Decay i enhanced by ome New Phyic (NP) model Any detection with current enitivity would be clear evidence of NP Current bet limit from LHCb (LHCb-CONF--5) (D μ μ - ) 95% C.L. et limit from factorie elle: (D μ μ - ) 9% C.L. ' ' ' ' Augut 3, 6 Joe.Lazo-Flore@cern.ch

7 Strategy Calculate the branching fraction by mean of the ratio: D* D (μ μ - )π /D * D (K - μ ν)π Where D* D π i the control channel D K - μ ν i the normalization channel The trategy wa to meaure the ratio in uch a way that mot of the ytematic uncertaintie cancel out Normalization channel choen for thi purpoe Firt time a emi-leptonic channel i being ued Limitation: Single muon trigger i need for the normalization channel Augut 3, 7 Joe.Lazo-Flore@cern.ch

8 Event Selection Normalization channel Signal μ μ D D D * (PV) K - D * (PV) μ - π ν π Muon: Tight quality η <., p T > 3 GeV including the trigger etting muon Kaon: Tight quality η <., p T >.8 GeV recontructed with kinematic conideration Primary and econdary vertex (PV and SV): Vertex probability > %, 3D ditance ignificance > 3 Signal only requirement: co α >.99, where α i the angle between the D momentum and the PV-SV direction (pointing angle) Pion: Track p T >.6 meaured from the PV Augut 3, 8 Joe.Lazo-Flore@cern.ch

9 Ma Difference function obtained from the WS ample. The fit return ± 4 D K µ ν candid ) Event/(.5 MeV/c CMS preliminary 8 6 = 7 TeV L = pb ) Event/(.5 MeV/c CMS preliminary ) Event/(.5 MeV/c = 7 TeV 35 CMS preliminary L = pb 3 5 = 7 TeV L = 9 pb # M=M(Kµ!")-M(Kµ!) (MeV/c ) Figure : M = M(K µ νπ ) M(K µ ν) for the RS ample with fit uperimpoed point 7 are75 the data, the blue 4line45 how5 the fit55 function 6 compoed 65 of 7 two Gauian 75 pl background function modelled by the WS. Thi background function i hown a a dahe # M=M(Kµ!")-M(Kµ!) (MeV/c ) " M=M(µµ!)-M(µµ) (MeV/c ) line. Normalization ample i fitted to extract N(Kμν) Signal: two gauian ackground: modeled by the ame ign K-π ample Augut 3, Signal: No evidence of D μ μ - from D * ackground i fitted to empirical function: Figure how M = M(µ µ π ) M(µ µ ) for the D µ µ analyi (data fro even period). The uperimpoed fit i a tandard function ued to model the backgrou the M ditribution: f ( M) =p [( M M π ) / p ( M M π ) 3/ ], where p a are the fit parameter and M p π i the pion ma. and p are fit parameter and M π i pion ma From the event of Figure, with the additional cut M M PDG < 3 MeV where 3 correpond to time the ma reolution meauredjoe.lazo-flore@cern.ch in MC, we obtain the µ µ inv

10 D μ μ - Upper Limit The upper limit on the branching fraction i determined by (D µ µ ) (D K µ ν) N(µµ) N(Kµν) a(kµν) a(µµ) trig(kµν) trig (µµ) rec(kµν) rec (µµ) Where: (D K - μ ν) = (3.3 ±.3) - i the normalization branching fraction (PDG) N(μμ) i the 9% CL upper limit on the D μ μ - yield N(Kμν) i the number of D K - μ ν candidate a and ε are the acceptance and efficiency of the two mode Augut 3, Joe.Lazo-Flore@cern.ch

11 D μ μ - Reult Acceptance and efficiency ratio are determined with MC Sytematic uncertaintie Acceptance and efficiency MC and data driven method Underetimated trigger efficiencie Contamination from D K *- (K - π )μ ν PDG uncertainty for D Kμν ) Event/(.5 GeV/c CMS preliminary = 7 TeV L = 9 pb Dimuon invariant ma (GeV/c (D μ μ - ) (9% CL) ) Augut 3, Joe.Lazo-Flore@cern.ch

12 Search for the (d) μ μ - decay Motivation: Decay are heavily uppreed in the SM SM expectation i: ( μ μ - ) = (3.3 ±.7) -9 ( μ μ - ) = (.7 ±.) Thi i becaue: It require a flavor-changing neutral current (FCNC) tranition Decay i helicity uppreed by a factor of (m μ /m ) Internal quark annihilation within meon Reduce decay rate by additional factor of (f /m ) Thee procee are excellent probe for new phyic HDM enhancement: (tan β) 4 MSSM enhancement: (tan β) 6 Contrain parameter region Augut 3, arxiv:8.934v b b (d) β) 6 Upper limit (R; 95% CL) Z, H,h,... W, H t,c,u Joe.Lazo-Flore@cern.ch ~ d t t W, χ ~ ~ W, χ - SM:! µ µ CLEO elle AAR ~ l ν CDF D LHCb CMS LHC comb. µ µ l l - SM:! µ µ C( Year

13 Long lived Well recontructed econdary vertex Momentum aligned with flight direction Ma around the m ackground Two independent emileptonic decay, One emileptonic () decay and one miidentified hadron _ Rare ingle decay Peaking, e.g. K K - Analyi Overview Signal ignature Two muon from one decay vertex and nothing ele µ _ µ ting) Non-peaking, e.g. K - μ ν Event with not well-recontructed econdary vertice µ µ Augut 3, 3 Joe.Lazo-Flore@cern.ch

14 Methodology Meaurement of the branching fraction relative to normalization channel Similar trigger and election to reduce ytematic uncertaintie ( µ µ ; 95%C.L.) = N(n ob,n,n S ; 95%C.L.) ε N = N(n ob,n,n S ) ε L σ(pp ) Augut 3, = N(n ob,n,n S ) N( ± J/ψ K ± ) A ε A Calibration/validation of MC: ± J/ΨK ± normalization with high tatitic J/ΨΦ ignal MC (p T, iolation,...) Analyi i done in two channel arrel - both muon η <.4 etter ignal/background ratio Good ma reolution (36 MeV) Endcap - at leat one muon with η >.4 Add more tatitic (σ(m) 7 MeV) ana ε ana a.u. ε µ ε µ.3.. ε trig ε trig f u f ( J/ψ [µ µ ]K) Toy (ideband) Toy (blinded)!µµ!µµ rare peaking G rare l G m µµ [GeV] 4 Joe.Lazo-Flore@cern.ch

15 Event Selection: Vertex Dicriminating Chooe one primary variable vertex Pointing longitudinal angle α3d impact parameter (z poition) vertex refit without fit quality ignal χ /doftrack Flight length ignificance l 3d /σ(l 3d ) Dicriminating variable 3D impact parameter (δ 3D ) and ignificance pointing angle α 3D (δ 3D /σ(δ 3D )) PV vertex fit quality χ /dof flight length ignificance 3d /σ( 3d ) Selection optimized for bet upper limit Frozen before unblinding 6 4 Augut 3, l 3D 3D impact parameter δ 3D and ignificance δ 3D /σ(δ 3D ) (ideband) - " µ µ (MC) ! 3D (ideband) " µ µ (MC) ! /dof (ideband) - " µ µ (MC) l 3D /!(l ) 3D p µµ α 5 Joe.Lazo-Flore@cern.ch /. cm /. cm µ µ 3D CMS, 4.9 fb Preliminary (ideband) = 7 TeV - 8 " µ µ (MC) (ideband) - " µ µ (MC) ! 3D

16 Event Selection: Iolation Primary vertex iolation, ued to minimize MC/data dicrepancie and maximize background rejection!!"#$%&#'()#'*(#'(,*(-./%.(*.*34( 3 For track in cone with R <.7 with p T >.9 GeV Aociated! to ame )*',(-#(./'/./(3,%-%(,/"456%'4/"(%',(.%7/./(89:(5;4&#'( PV or with dca > 5 μm if not aociated with PV!!"#$%&#'(#'(,*(5*)#'6%.(*.*34( (ideband) -! µ µ (MC) iolation Augut 3, 3 ( ( I = p! /.5 cm 3-6! µ µ (MC)! D*.85(#=(4$#"(-5%49"(/'(, 4% (E(FG(..(%',(6 ) (H(FI(J@( 4 CMS, 4.9 fb Preliminary = 7 TeV CMS, 5 fb = 7 TeV! </"-%'4(#=(->(4$#""-(-5%49(-#(?@(A, (ideband) 4% C( (ideband) -! µ µ p! ( ) ( ) p! (MC) " trk [cm]!"#$%&#'( d ca µ µ 7%%("/6*89%'6"("("/:'%$(;<4( /.5 cm 6 CMS, 4.9 fb Preliminary = 7 TeV (ideband) -! µ µ (MC) z (ideband) -! µ µ (MC) cloe N trk 6 Joe.Lazo-Flore@cern.ch 3 CMS, 4.9 fb P

17 Pileup Independence Determine election efficiency v N PV in data dataet:.5.5 N PV 8 RMS(z) 5.6 cm efficiency.95.9 efficiency.95.9 efficiency Augut 3, ± J/ΨK ± J/ΨΦ In MC: checked ε for N PV < 6 N PV > efficiency No pileup dependance l 3D /!(l ) > 5 3D N PV l 3D /!(l ) > 5 3D N PV efficiency.85.8 dca >.5 cm dca >.5 cm 7 Joe.Lazo-Flore@cern.ch N PV N PV efficiency I >.8 N PV I > N PV

18 Meaurement of ± J/ΨK ± Ue identical election a for dimuon, plu 3. <m(µµ) < 3. GeV Needed for the extraction of the branching fraction Same election a for ignal, plu 3. < m(μμ) < 3. GeV p T (μμ) > 7 GeV p T (K) >.5 GeV Fit pdf: p (µµ) > 7 GeV, p (K) >.5 GeV all track ued in vertexing Fit function ignal: double Gauian Augut 3, Signal: double Gauian partially kg: exponential recontructed error function at 5.45 decay GeV for J/ΨK * μ μ - K - (π ) decay background: exponential error function J/ψ K µ µ K (π ) arrel Endcap Acceptance.6 ±.6. ±.6 ε tot. ±.9.3 ±.4 N ob 87 ± ± 3 Sytematic error on yield: 5% /. GeV /. GeV arrel [GeV] Endcap 8 Joe.Lazo-Flore@cern.ch /. GeV m µµk [GeV] m µµk CMS, 4.9 fb

19 Unblinded Reult /.5 GeV arrel ignal window ignal window /.5 GeV Endcap ignal window ignal window Augut 3, [GeV] m µµ [GeV] Variable µ µ arrel µ µ arrel µ µ Endcap µ µ Endcap ε tot.9 ±..9 ±..6 ±..6 ±. N exp ignal.4 ±..7 ±.4. ±..3 ±.8 N exp peak.33 ±.7.8 ±.6.5 ±.3.8 ±. N exp comb.4 ± ±.5.76 ±.35.4 ±.53 N exp total.97 ± ±.65. ± ±.56 N ob 4 m µµ 9 Joe.Lazo-Flore@cern.ch

20 Upper Limit Reult upper limit (95%CL) oberved expected ( µ µ ) ( µ µ ) ± σ ± σ ± σ ± σ µµ µµ Augut 3, Joe.Lazo-Flore@cern.ch

21 CL LHC Combined Reult LHC combination ( μ μ - ) 4.(3.7) -9 at 95(9)% CL Combined reult from ATLAS, CMS and LHCb Getting cloe to the SM expectation ( μ μ - ).8(.67) -9 at 95(9)% CL Combined reult from CMS and LHCb CMS PAS PH-9 LHCb-CONF--7 ATLAS-COM-CONF--9.8 ATLASCMSLHCb CL.8 CMSLHCb (! µ µ - ) [ ] Augut 3, (! µ µ ) [ Joe.Lazo-Flore@cern.ch ]

22 Interpretation Example (GeV) m Empty region due to previou upper limit and other publihed data 5 - m # µ v tan" (CMSSM prediction for µ ) Iajet Calculation m / = 78 GeV A = 3 GeV Excluion zone (SM Value)! (GeV) m 5 - m # µ v tan" (NUHM prediction for µ ) (SM Value)! tan"! Stronget impact at large tanβ 5 Iajet Calculation m / = 3 GeV A = 3 GeV µ = m A = 4 Excluion zone tan"! Augut 3, Joe.Lazo-Flore@cern.ch

23 Concluion Shown here are the reult of FCNC decay D μ μ - and (d) μ μ - (D μ μ - ) (9% CL) ( μ μ - ) (95% CL) ( μ μ - ).8-9 (95% CL) LHC combination ( μ μ - ) (95% CL) ( μ μ - ).8-9 (95% CL) CMS i producing high quality reult More reult to come from data Analyi of data ongoing Augut 3, 3 Joe.Lazo-Flore@cern.ch

24 candidate event 4

25 Kinematic: Simulation v / GeV 5 " J/! K /.5 GeV 5 " J/! K /. GeV 5 5 " J/! K p [GeV] T, µ 5 5 p [GeV] T, µ -!() p () [GeV] T leading muon p ub-leading muon p / GeV # J/"! /.5 GeV 5 # J/"! 6 4 /. GeV 5 5 # J/"! p [GeV] T, µ Augut 3, 5 5 p [GeV] T, µ -!() p () [GeV] T 5 Joe.Lazo-Flore@cern.ch

26 Vertexing # J/" K # J/" K 5 5 # J/" K /. cm 5 5 # J/" K l 3D /!(l ) 3D ! /dof ! 3D ! 3D flight length ign. vertex χ /dof 3D pointing angle 3d impact param. 8 6 $ J/# " $ J/# " 5 $ J/# " /. cm 5 $ J/# " l 3D /!(l ) 3D ! /dof ! 3D ! 3D Augut 3, 6 Joe.Lazo-Flore@cern.ch

27 Iolation 4 3 " J/! K " J/! K /.5 cm " J/! K $ J/# K iolation cloe N trk [cm] d ca 3 4 5! 3D /"(! ) 3D iolation # cloe track ditance of cloet trk 3d impact param. ign. 4 # J/"! # J/"! /.5 cm 6 4 # J/"! 6 4 % J/$ # iolation Augut 3, cloe N trk [cm] d ca 3 4 5! 3D /"(! ) 3D 7 Joe.Lazo-Flore@cern.ch

28 linded Reult /.5 GeV.5 arrel ignal window ignal window /.5 GeV.5 Endcap ignal window ignal window.5.5 Augut 3, [GeV] m µµ [GeV] ackground = combinatorial rare (MC hape) Contant hape aumed for combinatorial Combinatorial event in ignal window: Subtract rate event from ideband Scale remaining event to the difference width of the region m µµ 8 Joe.Lazo-Flore@cern.ch