Setting the Charm Decay Scale

Transcription

1 Setting the Charm Decay Scale e e D D D D γ γ π π Peter Onyii Cornell Univerity CLEO Collaboration Texa A&M, 21 Apr 26 Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 1 / 38

2 Outline Intro to CLEOc Open charm phyic at CLEOc Hadronic branching fraction analye D /D D Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 2 / 38

3 CESR Peter Onyii I CESR i a 768 m circumference e e torage ring I Provide colliion for CLEO and beam for the Cornell High Energy Synchrotron Source I Originally deigned to operate at Ecm = 9 12 GeV, ran motly at Υ reonance with (at the time) worldrecord luminoitie ( ) I Upgraded to provide colliion down to Ecm = 3 GeV Charm Hadronic BF Texa A&M, 21 Apr 26 3 / 38

4 CESRc Upgrade Beam Trajectory Beam Trajectory Old CESR could not cool the beam at low energy enough for good luminoity (ynchrotron power E 4 ) CLEO can no longer run imultaneouly with CHESS Solution: 12 wiggler magnet intalled Antiolenoid cancel energydependent effect of CLEO field on beam Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 4 / 38

5 CLEOc Upgrade CLEOc SC Quadrupole Pylon Solenoid Coil Barrel Calorimeter Ring Imaging Cherenkov Detector Drift Chamber Inner Drift Chamber / Beampipe CLEOIII ilicon vertex detector replaced with (all tereo) drift chamber (typical z reolution 7 µm) SC Quadrupole Rare Earth Quadrupole Endcap Calorimeter Iron Polepiece Solenoid magnetic field changed from 1.5T to 1.T to compenate for lowermomentum track Magnet Iron Barrel Muon Chamber DAQ, trigger, oftware, etc. from CLEOIII with only minor change Particle ID (from de/dx, Čerenkov) better due to lower p track Muon ytem now only ueful for high momentum (e.g. J/ψ µ µ ), Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 5 / 38

6 CLEOc Miion Enable meaurement at other experiment Find branching fraction of reference mode Tet theoretical input to Bfactorie Meaure trong phae in D ytem Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 6 / 38

7 CLEOc Miion Enable meaurement at other experiment Find branching fraction of reference mode Tet theoretical input to Bfactorie Meaure trong phae in D ytem Explore QCD dynamic in the charm region and below Charmonium D Dalitz tudie Light meon in radiative decay Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 6 / 38

8 CLEOc Miion Enable meaurement at other experiment Find branching fraction of reference mode Tet theoretical input to Bfactorie Meaure trong phae in D ytem Explore QCD dynamic in the charm region and below Charmonium D Dalitz tudie Light meon in radiative decay Search for new phyic D D mixing CP violation Rare decay Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 6 / 38

9 Open Charm Decay In A Nuthell Leptonic decay: D c W l Probe wavefunction at origin (decay contant f D, f D ) d ν Tet lattice QCD and meon tructure model l Semileptonic decay: W ν Probe overlap of initial and final hadron tate D c ū ū (form factor f (q 2 )... ) Tet LQCD and decay model Hadronic decay: D c W d u Reference mode normalize decay QCD dynamic Search for new phenomena: CP violation, D D mixing Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 7 / 38

10 Abolute Charm Branching Fraction What i the problem? Meaurement of decay to c quark depend on recontructing decay of light charmed meon and baryon Branching fraction meaurement can be limiting ytematic Since b c i a dominant decay mode, B meaurement often rely on knowing variou D () BF Affect preciion meaurement of Z c c (H c c... ) Reference mode (D π, D π π, D φπ ) normalize virtually all other branching fraction Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 8 / 38

11 General Method (Follow pioneering analyi by Mark III... ) Exploit lowenergy production procee: At 3.77 GeV, open charm only produced a D D and D D At 4.17 GeV, D produced almot entirely a D D In the event we ue, a meon of interet i alway produced along with it antiparticle We chooe a et of mode and recontruct ingle tag (we recontruct a decay) and double tag (we recontruct both decay) A double tag can count a ingle tag For N decay mode we have 2N ingle tag (eparated by charge) and N 2 double tag Since the ingle tag yield in mode i i proportional to B i, and the double tag yield for i, j i proportional to B i B j, we can determine each of the branching fraction Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 9 / 38

12 Method Numeric Single tag yield: N i = N DD B i ɛ i Double tag yield: N ij = N DD B i B j ɛ ij Branching fraction: B j = N ij N i ɛ i ɛ ij In practice, we fit all the yield imultaneouly Maximize power: limiting tatitical uncertainty i total double tag in every mode Bad χ 2 omething wrong... Can correlate ytematic Obtain croection a well Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 1 / 38

13 D /D Analyi (PRL ) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

14 Data Ued L = (55.8 ±.6) pb 1 at E cm GeV, at the peak of the ψ(377) reonance CLEOc dataet a of end of 24 We are updating to ummer 25 (281 pb 1 ) Alo exploit 3 pb 1 of CLEOc ψ data for ytematic tudie operating point σ(hadron) σ(µ µ ) PDG E cm DD threhold Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

15 D Hadronic Decay Overview Reference decay mode are D π and D π π 18 ingle tag, 45 double tag mode Decay PDG 24 fit Rel uncert D π 3.8% 2.4% D π π 13.% 6.2% D π π π 7.46% 4.2% D π π 9.2% 6.5% D π π π 6.5% 17% D S π 1.41% 6.7% D S π π 4.85% 31% D S π π π 3.55% 14% D π.89% 9.% Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

16 The CLEOc DHunter Guide Charged, π ditinguihed uing de/dx (all momenta) and Čerenkov (for high momentum) Find π by combining pair of iolated hower in the CI calorimeter, requiring 3σ conitency with π ma (σ 6 MeV) Find S by combining pair of track that lie within a ma window Two crucial kinematic variable: Beamcontrained ma M BC = Ebeam 2 p2 D tet that total momentum of candidate i right E = E D E beam tet particle ID, i enitive to miing particle D Tagging will olve the world problem and make it unny in Ithaca Anon. Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

17 Yield extraction Event / (.2 GeV/c 2 ) Event / (.12 GeV/c 2 ) DATA: Single tag D π D π π D π S D π π π π D π D π S π D π π π D π π π S M (GeV/c 2 ) D D M (GeV/c 2 ) D D D π DATA: Double tag projection Event / (.12 GeV/c 2 ) M (GeV/c 2 ) Fit ignal with a priori function of phyical parameter (detector momentum reolution, beam energy pread, ψ(377) linehape, ISR pectrum) Smooth background fit a combinatoric phae pace ( ARGUS function ) Peaking background etimated from known BF and ubtracted In double tag, fit 2D plane of M BC (1) v. M BC (2) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

18 Sytematic tudie uing ψ Clean decay ψ J/ψ π π and J/ψ π π ued to compare tracking and π efficiencie in MC and data Recontruct J/ψ and one pion; compute recoil ma: peak at pion ma Find fraction of uch event with other pion recontructed Right: Plot for J/ψ π π,.15 < co θ π <.55 ɛ = (95.89 ±.2)%; agree with MC within tatitic Event / (.15 GeV ) Event / (.15 GeV ) piprime_data_new_cotheta_p_piprime.evt Fit parameter DATA 2nd π found igma2 =.1612 ± igma1 =.836 ± mpiq2 =.2214 ± mpiq1 =.1744 ± fract =.5 ± Npeak = 923 ± NBkgdExp = 98 ± M2mi (GeV) piprime_data_new_cotheta_p_nopiprime.evt Fit parameter DATA 2nd π not found p2 = 14.8 ± Npeak = 396 ± NBkgd = 457 ± NBkgdExp = 1. ± M2mi (GeV) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

19 Double DCSD: Quantum Effect Conider double tag with D π: Dominant decay i D π (D π ). However there are doubly Cabibbouppreed decay D π and vice vera. The ratio of amplitude i the complex number A, which encode both the uppreion and a relative trong interaction phae δ. The direct contribution of the double DCSD amplitude in double tag i negligible. But you have interference between D D going Cabibboallowed to both mode and double DCSD: I = 1 A 2 2 = 1 2 A 2 co 2δ O( A 4 ) A 2.4%; we don t know co 2δ:.8% uncertainty on D double tag rate! (We expect co δ 1; we re doing analye to tet thi... ) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

20 Sytematic uncertaintie Source Fractional uncertainty (%) Tracking/ S /π.7/3./2. per particle Particle ID.3 per π, 1.3 per Trigger efficiency <.2 E cut per D FSR modeling.5 per ingle tag ψ width.6 Reonant ubtructure Event environment. 1.3 Yield fit function.5 Mic. event election.3 Double DCSD interference.8 in neutral double tag D π uncert 2.3%, D π π uncert 2.8% For thee, larget contributor are kaon PID and E cut Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

21 Reult Branching fraction... Mode Value B(D π ) (3.91±.8±.9)% B(D π π ) (14.9 ±.3 ±.5)% B(D π π π ) (8.3 ±.2 ±.3)% B(D π π ) (9.5±.2±.3)% B(D π π π ) (6. ±.2 ±.2)% B(D S π ) (1.55 ±.5 ±.6)% B(D S π π ) (7.2 ±.2 ±.4)% B(D S π π π ) (3.2 ±.1 ±.2)% B(D π ) (.97 ±.4 ±.4)% σ D D (nb) σ D D (nb) σ DD (nb) σ D D /σ D D 2.79 ± ± ± ± and cro ection from 55.8 pb 1 Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

22 Reult comparion PDG CLEOc B(CLEOc) B(PDG) PDG B(D π ) previou abolute meaurement and PDG fit PDG CLEOc Br. Ratio(CLEOc) Br. Ratio(PDG) PDG B(D π π ) previou abolute meaurement and PDG fit Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 2 / 38

23 D /D Summary and Outlook Branching fraction from 56 pb 1 have preciion comparable to world average Updating to 281 pb 1 : we will be ytematiclimited Aiming for < 1.5% uncertainty on reference mode Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

24 D Analyi (In Progre) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

25 D Hadronic Decay Overview The claic reference decay ha been the excluive mode D φπ π Eentially all other decay have branching ratio to thi mode Thi caue problem ince φ ignal i ambiguou given the preciion we will oon achieve We intead meaure incluive branching fraction. Mode ued Decay PDG 24 BF (%) D S 1.8 ±.55 D π 4.3 ± 1.2 D π π D π π π 1. ±.28 Relative uncertaintie are roughly 25 3%, limited by the φπ BF in PDG 24. BaBar ha a 25 φπ meaurement, 34% higher than the PDG, with 13% error. Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

26 The φπ problem φ π Invariant ma (GeV) φ π SIDEBAND Invariant ma (GeV) m inv, D bkg = / (15., 15.8) 18 bkgbar = / (14., 14.8) c1 =.217 / (.1,.1) 16 yield = / (25.1, 25.8) 14 yieldbar = / (24.6, 25.4) m inv, D bkg = 5.73 / (7.5, 8.3) 18 bkgbar = / (6.6, 7.4) c1 =.154 / (.2,.2) 16 yield = / (6.5, 7.2) 14 yieldbar = / (7.2, 7.9) 1 φ π Invariant ma (GeV) φ π SIDEBAND Entrie 2384 Mean 1.5e16 RMS Invariant ma (GeV) Event / (.325 GeV ) m inv, D Event / (.325 GeV ) Expect (f (98) )π to contribute to any φ ma region, with badly controlled parameter Correction might be on the order of 5% or more but depend on experiment ma window, reolution, angular ditribution requirement! Event / (.325 GeV ) helicity angle, phi band m inv, D khlangphi Event / (.325 GeV ) Looking at lowma pair (m() < 1.5 GeV) we ee evidence for calar production by looking at helicity angle helicity angle, low ma Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

27 Dataet and Landcape Ue 76 pb 1 of data collected at E cm 417 MeV a part of the recent (Aug. Jan.) D energy can and data run Choe running point for maximal D production Dominant D production channel in thi region i D D, 1 nb D, D event produced at 7 nb, are the major background operating point CLEOc Scan Preliminary E cm D D threhold PDG Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

28 Production Channel We ue event with the topology e e D ± D D D (γ, π ). We do not recontruct the γ or π. We ue the momentum of the D candidate to elect for event with an intermediate D. (The quantity m BC = Ebeam 2 p2 D i a proxy for momentum.) We can ue a looe cut to include the daughter of D, or a tight cut for the directly produced D m BC, D S Direct D D from D MC mbcplt_4 m BC, D S Entrie 2178 Mean 2.2 RMS Data Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

29 inematic Separation minv (GeV) minv v. mbc for π candidate MC 2.1 D refl D D D D D D DD D D p 2 2 Ebeam ~pcand Peter Onyii Charm Hadronic BF mbc (GeV) Texa A&M, 21 Apr / 38

30 D D Wrinkle We do a binned maximum likelihood fit for all the oberved yield (utilizing Poion tatitic for double tag) Maximizing tatitical power important given relatively low D croection The π mode i 62% of all ingle tag, but π/π i only 26% of the double tag yield Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

31 Background and Reflection Crofeed between D mode from S π π i Cabibbouppreed Ue vetoe and ideband Peaking tructure can arie from reflection: for example, the decay chain D D π π ha correct m BC, peak at 2.6 GeV. We veto certain ma region; e.g. for π we reject event conitent with D. Thi doen t affect ignal but make the background eaier to model ma, π candidate Data π D kk Entrie 294 Mean 1.43 RMS.2443 π ma in π π candidate Data ππ D π kkpi Entrie Mean RMS Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

32 Yield extraction DATA: π Single Tag Event / (.325 GeV ) m inv, D m(d ) (GeV/c ) π D Invariant ma (GeV) m v. m D D (D bkg = / (87., 87.7) Event / (.325 GeV ) bkgbar = / (86.6, 87.3) c1 =.98 / (.,.) 6 yield = / (52.9, 53.6) m inv, D yieldbar = / (54.1, ) π / D π D Invariant ma (GeV) DATA: π /π Double Tag π ) Fit ingle tag ignal with double Gauian or Crytal Ball function (parameter fixed from Monte Carlo) plu a linear background Each charge done eparately In double tag, count event in ignal and ideband boxe Combinatoric background i flat in m(d ) m(d ), ha tructure in m(d ) m(d ) m(d 2 ) (GeV/c ) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr 26 3 / 38

33 Data Reult m(d ), D S m(d 788 ± 34 Event / 3 MeV m(d ), D π 3344 ± 77 Event / 3 MeV All double tag 2 m(d ) (GeV/c ) m(d ) (GeV) m(d ), D π π 79 ± 54 Event / 3 MeV m(d ), D π π π m(d ) (GeV) 539 ± 41 Event / 3 MeV m(d 2 ) (GeV/c ) All double tag Event / 8 MeV ignal 28 ideband m(d ) (GeV) m(d ) (GeV) m(d ) m(d ) (GeV) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

34 Sytematic uncertaintie Source Fractional uncertainty (%) Tracking/ S /π.35/1.1/5. per particle Particle ID correlated by decay Reonant ubtructure 6. correlated by decay Fit procedure 3.5 in fit reult Event environment 3.5 in ππ Initial tate radiation correction 5 per ingle tag B(D π D ).7 in ππ, πππ Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

35 Preliminary Reult for D Mode CLEOc (%) PDG 24 fit (%) B( S ) ± ±.55 B( π ) ± ± 1.2 B( π π ) ±.46 B(π π π ) ±.5 1. ±.28 S PDG 24 fit 1 CLEO Preliminary, 76 pb S PDG 24 fit PDG 24 fit, BR error only 1 CLEO Preliminary, 76 pb π π π π π π π π π π Branching Fraction (%) BF/PDG 24 fit Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

36 Comparion with BaBar φπ Can we compare with the BaBar B(D φπ ) reult? We can ue the PDG fit branching ratio... PDG 24 fit PDG 24 BR BaBar φπ S 1 CLEO Preliminary, 76 pb S 1 CLEO Preliminary, 76 pb π π π π π π π π π PDG 4: 3.6% Branching Fraction (%) We are more conitent with 3.6% than 4.8% π π π BaBar 5: 4.81% Branching Fraction (%) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

37 D Summary and Outlook We have preliminary abolute branching fraction for four D decay mode from 76 pb 1 of data Preciion about 11% for allcharged mode Incluive π π i a firt meaurement The meaured BF are conitent with the PDG 24 fit We are actively working on adding more mode (epecially decay with η, η ) We are aiming for < 4% uncertaintie with full CLEOc dataet Already have more than 1 pb 1 additional data on tape! Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

38 Backup Slide Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

39 Background Nonpeaking background removed in the yield fit Peaking background are from crofeed between mode we conider, and contamination from other mode Latter dominated by Cabibbouppreed decay in S mode, e.g. prompt D 5π fake D S 3π; in ome mode up to 3% correction Etimate background to ingle and double tag with PDG branching fraction and efficiencie from MC, ubtract from meaured yield Fake type kpi Event / (.6 GeV ) MC 3x data yield = 228 ± Beam contrained ma (GeV) 15 DCSD decay D π faking D π in 3x MC ample. In data, contribute.15% of oberved peak. Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38

40 Reonant Subtructure φ π Invariant ma (GeV) * Invariant ma (GeV) φ π Invariant ma (GeV) * π Invariant ma (GeV) m inv, D bkg = / (15., 15.8) 18 bkgbar = / (14., 14.8) c1 =.217 / (.1,.1) 16 yield = / (25.1, 25.8) 14 yieldbar = / (24.6, 25.4) m inv, D bkg = / (35.2, 35.9) bkgbar = / (35.2, 36.) 2 c1 =.175 / (.,.) 18 yield = / (27., 27.7) yieldbar = / (28.7, ) m inv, D bkg = / (19.6, 2.3) bkgbar = / (19.2, 2.1) 4 c1 =.11 / (.1,.1) yield = / (14.8, ) yieldbar = / (15.2, 15.9) m inv, D bkg = / (32.8, 33.7) bkgbar = / (33.4, 34.2) φ π Invariant ma (GeV) * Invariant ma (GeV) 5 c1 =.125 / (.,.) 5 yield = / (19.4, 2.) yieldbar = / (2.3, 2.6) φ π π Invariant ma (GeV) * π Invariant ma (GeV) Event / (.325 GeV ) m inv, D Event / (.325 GeV ) Our Monte Carlo ha ome reaonable mixture of intermediate reonance Our efficiencie depend on the intermediate tate We reweight the expected efficiencie by comparing data yield with MC expectation Size of correction i larget ytematic for π π The correction for a given mode affect that mode BF only Event / (.325 GeV ) Event / (.325 GeV ) Event / (.325 GeV ) m inv, D m inv, D m inv, D π Event / (.325 GeV ) Event / (.325 GeV ) Event / (.325 GeV ) Peter Onyii Charm Hadronic BF Texa A&M, 21 Apr / 38