γ from trees roadmap Jim Libby (University of Oxford) 25/11/08 LHCb week Physics Plenary 1

Transcription

1 γ fom tees oadmap Jim Libby Univesity of Oxfod 5/11/08 LHCb week Physics Plenay 1

2 Gamma, Missoui St Louis 5/11/08 LHCb week Physics Plenay

3 Outline Motivation and intoduction CM Standad Candle A eminde of ou modes and expected pecision: In paticula 0.5 fb 1 sensitivity Status of baseline channels and 0 hh *0 ds h TCPV Issues to be addessed befoe fist measuement many in common Outlook 5/11/08 LHCb week Physics Plenay 3

4 Seaching fo new physics with CM b d W ν e u d 0 e b d t W b d 0 0 W t TREE LOOP espite success of M mechanism to descibe CP best constaints fom loop pocesses est pospect to impove tee level measuements is γ CMfitte 08:γ= fom diect measuements 5/11/08 LHCb week Physics Plenay 4

5 Intoduction ± ± decays involve b c and b u tansitions A = 0 * 0 i δ γ A V us A = A e Stong phase diffeence V cb Access γ via intefeence when 0 and 0 decay to the same final state V ub These measuements ae theoetically clean No penguin CM standad candle * V cs lagest coection is sub-degee fom -mixing Numbe of stategies to study such decays ± ± with hh, and 0 S 0 hh* Ratio of absolute amplitudes of colou/cm suppessed to favoued ~0.1 5/11/08 LHCb week Physics Plenay 5

6 5/11/08 LHCb week Physics Plenay 6 Look at CS, CF and CP decays of Unknowns : ~0.1, δ, δ, γ, N, N hh =0.06 well measued With knowledge of the elevant efficiencies and Rs, the nomalisation constants N, N hh can be elated to one anothe Impotant constaint fom CLEO-c and -mixing on δ Oveconstained: 6 obsevables and 5 unknowns cos 1 cos 1 cos, cos 1, cos, cos 1 γ δ γ δ γ δ δ γ δ δ γ δ δ γ δ δ Γ Γ Γ Γ Γ Γ h h h h hh h= o

7 5/11/08 LHCb week Physics Plenay 7 Fou-body AS can also be used fo AS style analysis Howeve, need to account fo the esonant substuctue in made up of *ρ, a 1 160,., in pinciple each point in the phase space has a diffeent stong phase associated with it - 3 and 4 body alitz plot analyses exploit this vey fact to extact γ fom amplitude fits Atwood and Soni hep-ph/ show how to modify the usual AS equations fo this case Intoduce coheence paamete R 3 which dilutes intefeence tem sensitive to γ R 3 anges fom 1=coheent dominated by a single mode to 0=incoheent seveal significant components Coheence paamete measued at CLEO-c see late cos γ δ δ Γ R = s s s s s s s s d A d A d e A A e R i i 3 3 δ δ

8 0 hh *0 b d V cb 0 0 oth amplitudes colou suppessed leads to 0 ~0.3 fom CM Po: lage intefeence V 0 ub c b u 0 u c s s d *0 d *0 d Con: educed banching faction ~10% of Recent AAR constaint on 0 [0.18,0.34] at 1σ Sodini@CM08 All expeimental hh issues elevant fo this mode In addition, must account fo non- * contibution to Studies indicate limited dilution ~5% with small additional systematic uncetainty hep-ph/ /11/08 LHCb week Physics Plenay 8

9 0 Exploit γ sensitive diffeences between the 0 S alitz plots fom and A A = = f m f m, m, m 0 ± m = S invaiant mass and f m±, ± i γ δ i γ δ f m GeV / c est expeimental constaints on γ come fom measuements of this mode at e e factoies Two methods investigated e e m m f m Model dependent unbinned analysis with isoba model of alitz amplitudes Po: full statistical powe Con: lage systematic uncetainty elated to model Model independent binned analysis exploiting stong phase infomation fom CLEO-c Po: easie measuement counting in bins including systematic studies Con: lose of statistical powe, m, m alitz amplitudes m 0 GeV/ c m 5/11/08 LHCb week Physics Plenay 9

10 The classic: s s and d Next few slides lagely fom A. Cabone s talk at CM Conside tee diagams below and the 0 s 0 s mixing gaphs T1 T Intefeence between the tee diagams gives a time dependent analysis a clean access to γφ ds φ ds is the weak mixing phase which can be measued with high pecision the mixing phases φ d φ s is will be pecisely measued fom d J/ψ S s J/ψφ This allows a measuement γ! 5/11/08 LHCb week Physics Plenay 10

11 The classic: s s and d Constuct two asymmeties s s case 6 Obsevables, S, S, C, C, A Γ, A Γ Using the untagged analysis is possible to measue A Γ, A Γ Fo d case we only have 4 obsevables: C d, S d, C d, S d due to Γ d being vey small 5/11/08 LHCb week Physics Plenay 11

12 The classic: s s and d Obsevables ae function of γ, φ q, δ q and x q x paametes chaacteise level of intefeence a d,a s ae hadonic paamete of the ode of 1 x s is lage enough to be fit to the data x d must be constained extenally It is expected to have σx d ~10% by the end of LHCb data taking Measuements ely on all things equied to make s J/ψφ meauement, except it is less complicated because angula analysis not equied 5/11/08 LHCb week Physics Plenay 1

13 What we expected fom C04? 5/11/08 LHCb week Physics Plenay 13

14 Combined esults fo tee-level γ Given common paametes amongst the modes a global fit has been implemented [LHCb ] Cuently unknown leads to lagest vaiations in sensitivity Expect best o v. competitive esults with fist significant data CLEO-c inputs essential to these esults Weight of each mode in % 5/11/08 LHCb week Physics Plenay 14

15 Now the main challenge elive this C04 pefomance on fist data Sub-challenges 1. Maintain offline selection pefomance. L0 HLT1 HLT matches old L0 L1 HLT Old HLT always assumed to > 90% efficient 3. Contol of systematic uncetainties 4. Intefacing the equied extenal constaints and measuements to the analyses 5/11/08 LHCb week Physics Plenay 15

16 C06 selection studies C06 selection studies on the coe channels have been pefomed: hh - Mitesh Patel 0 hh* 0 Jacopo Nadulli and Stefania Ricciadi 0 S - Ying Li and Val Gibson ds s h Vava Gligoov Ongoing study of 3 in Oxfod Planned pesentation at next γ fom tees woking goup Next few slides efeing to numbes pe-hlt 5/11/08 LHCb week Physics Plenay 16

17 C06 selection studies hh Change in stategy fo C06 with tighte vetex and flight distance cuts Loosened 0 cuts to compensate Optimisation pefomed with H. Skottowe s tool used in 0 *µµ ottom line: simila pefomance to C04 0 hh* 0 Change in stategy fom C04 to have cuts the same fo all topologies Easie undestanding of elative efficiencies Optimised selection limited by backgound stats. Pefomance slightly wose than C04 fo CP 600 events 400 events 5/11/08 LHCb week Physics Plenay 17

18 C06 selection studies: 0 S Reoptimised selection tightening of LL cuts to educe backgound etailed study of backgound using X samples ette undestanding of diffeent types of backgound Pue combinatoic Real with anothe in the event andom LHCb Uppe limits on backgound ottom line: simila yield ~6.8k and /S~1 to C04 Much bette undestanding of bkg 5/11/08 LHCb week Physics Plenay 18

19 C06 selection studies ds h Selection optimised S /S fo d A few adjustments to eject min bias fb 1 esult S=1.5 M S/~5 Same as C04 Apply this selection fo s s with modified PI S=8.1k S/ [0.3,1.4] 90% 30% yield impovement ove C04 study simila S/ 4M inclusive b events ottom line: pefomance maintain & s impoved! 5/11/08 LHCb week Physics Plenay 19

20 Tigge studies A lot of time has been spent woking on the HLT selections: 50% of pesentations at meetings S. isbane, V. Gligoov, J. Nadulli, M. Patel, S. Ricciadi and P. Spadlin Symptomatic of the difficulties of tiggeing on multibody hadonic final states V. low efficiency when stiving to achieve < 10 Hz acceptance ate iggest issues uncoveed: Low default tacking efficiency Online eo paameteisation Min. bias emaining is dominated by ghosts 5/11/08 LHCb week Physics Plenay 0

21 Selection channel εhlt εl0 Mbias Mass window ate MeV % 4% 4 Hz m [-80,500] 88x70 1 m ±100 d hh * 0 d hh* 0 51% 45% 4 Hz m ±50 76x67 m ±150 hh 54% 45% 80x67 d,s s h s s 71% 45% 60Hz m ±500 86x83 s s 70% d 7% m [-00,100] s s ρ 0 s s ρ 67% 37% 45Hz m ±500 m ±15 mρ ±300 1 efftacking x effselection cuts Fom M. Calvi s compilation at the Octobe 16 th HLT-Physics wokshop 5/11/08 LHCb week Physics Plenay 1

22 ut Novembe is a month fo evolution 7 th Novembe 1917 olshevik/soviet evolution Gegoian calenda 5/11/08 LHCb week Physics Plenay

23 ut Novembe is a month fo evolution 7 th Novembe 1917 olshevik/soviet evolution Gegoian calenda 11 th Novembe 1974 iscovey of the J/ψ 5/11/08 LHCb week Physics Plenay 3

24 ut Novembe is a month fo evolution 7 th Novembe 1917 olshevik/soviet evolution Gegoian calenda 11 th Novembe 1974 iscovey of chamonium 0 th Novembe 008 Unveiling of HLT1.5 See Thusday am Plenay fo the details 5/11/08 LHCb week Physics Plenay 4

25 Topological tigge fom G. Guee New inclusive tigge which takes lage faction of bandwidth Pomising esults with HLT efficiencies > 90% fo * and s s Howeve, <60% fo alitz Also, optimised L0xHLT1 efficiencies ~30% geate elative than shown hee M. Gandelman 5/11/08 LHCb week Physics Plenay 5

26 Special case: 0 S Jaap Panman & Sean isbane /3 of offline selected 0 S downsteam tacks ae econstucted with Too CPU-intensive to un downsteam tacking on all HLT1 selected events Theefoe, only un when and chage ± fom ae consistent with signal decay: Use vetex, loose mass and pointing and planaity of vtx, and PV Pomising esults: 87% tack finding 90% topology 93% to then find 0 S Still being optimised in HLT envionment PV 0 s Just use 5/11/08 LHCb week Physics Plenay 6

27 Systematic uncetainties Fo AS/GLW modes significant systematics: nowledge of poduction and detection asymmeties Contolling knowledge of efficiencies between modes: contol channel 1 lage banching faction and ~0.005 so negligible CPV effects nowledge of PI efficiency * will be adequate ackgound paameteisation Ensuing we select enough sidebands Fo 0 S asymmeties less of a poblem 5/11/08 LHCb week Physics Plenay 7

28 Poduction and detection asymmeties Studies of the combination of poduction and chage asymmety fom J/ψ fo example Howeve, constained kinematics and topology of * 0 3 can be used to measue chage asymmety alone: Use 0 * µν to educe backgound, incease constaints and fo tiggeing peliminay wok by M. Patel and M. Adinolfi Good p coveage A fs measuement also handle on poduction efficiency 5/11/08 LHCb week Physics Plenay 8

29 Extenal constaints CLEO-c measuements ae essential fo model-independent 0 and impove AS/GLW sensitivities Fist measuement of binned aveage stong phase diffeences in 0 S Resulting uncetainty on γ is ~ Latest AAR model 7 Fist measuements of coheence paamete and aveage stongphase diffeence in 3 and 0 Have shown that CLEO-c info same as doubling data [LHCb ] Also, exchange with theoists the undestanding on x d fo TCPV in 0 3 5/11/08 LHCb week Physics Plenay 9

30 Conclusion and outlook Well defined selections in place fo most key modes Most significant aea of effot and concen is HLT We live in exciting times but still much to do Still some wok to be done on asymmety, sideband and contol measuements No measuements will be systematic limited to begin with Peliminay extenal inputs available fom CLEO-c and ae intefaced to ou paamete extaction In a good position to make wold best measuement of γ with 0.5 fb 1 5/11/08 LHCb week Physics Plenay 30

31 Outlook Thee have also been seveal new initiatives: s s S. lusk, S. Stone and L. Zhang d ρ and s s Y. Amhis and M.-H. Schune s φ [diect CP] S. Ricciadi and J. Nadulli Thee ae seveal modes unde peliminay investigation o still to be exploed d * 0 0 S and 0 S and 0 S 0 * and * In othe wods plenty of oppotunities to impove the tee-level measuement futhe 5/11/08 LHCb week Physics Plenay 31