1 / 24

analisys: Systematics checks

analisys: Systematics checks. Salvatore Fiore. Main ingredients. Cuts’ fine tuning to maximize sensitivity 2-dim sidebands: “sideboxes” Narrowed sideboxes approaching signal box MC photon efficiency curve EMC Cluster energy-position: MC-Data agreement.

arvid
Télécharger la présentation

analisys: Systematics checks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. analisys:Systematics checks Salvatore Fiore Salvatore Fiore K0K0analisys: some updates

  2. Main ingredients • Cuts’ fine tuning to maximize sensitivity • 2-dim sidebands: “sideboxes” • Narrowed sideboxes approaching signal box • MC photon efficiency curve • EMC Cluster energy-position: MC-Data agreement Salvatore Fiore K0K0analisys: some updates

  3. Cuts optimization Analysis cuts’ bounds have been chosen looking only at signal and bkgd MC, as each cut was added. However, to exclude personal biases from the analysis, an optimization on the selection cuts has been performed looking again only at signal and bkgd MC’s, and minimizing the quantity Here the quantity “#ev @ 90% CL” is evaluated from the background surviving events, using Feldman Cousins method for sensitivity (this is ok, no “expected mean bkgd” inconsistency) Salvatore Fiore K0K0analisys: some updates

  4. vs. cuts choice Previous choice Salvatore Fiore K0K0analisys: some updates

  5. Optimization effects • With this procedure, two of the last four kine cuts have been removed (non effective on bkgd) • The other cuts prooved to be already optimized, only E2miss-P2miss slightly loosened (±200  ±300) • Signal efficiency after this procedure is 21.5% (was 20.0%) • Residual MC background events now are 0 • Residual Data events still 1 Salvatore Fiore K0K0analisys: some updates

  6. MC-Data agreement checks From last phidec meeting To make sure of the MC correct behaviour, we made some checks on our selection variables: • We chose a sideband control sample, made by those events which did not survive both “KSKS invariant mass” and “E2miss-P2miss” cuts. • For these events, we evaluated the MC/data ratio for KSKS invariant mass and E2miss-P2miss distribution. Salvatore Fiore K0K0analisys: some updates

  7. 2001-02 MC-Data comparison From last phidec meeting MC/Data: 1.181±0.020 MC/Data: 1.153±0.020 Salvatore Fiore K0K0analisys: some updates

  8. 2005 MC-Data comparison From last phidec meeting MC/Data: 1.118±0.011 MC/Data: 1.110±0.012 Salvatore Fiore K0K0analisys: some updates

  9. MC-Data agreement From last phidec meeting The different distribution ratios are in good agreement, and confirm the generated 1:1 Mc-Data scaling factor. MC/Data ratios for the same distributions, looking at the events which do not pass that single cut (standard sidebands) have been checked. 1.1713 ±0.020 1.2171 ±0.011 1.2647 ± 0.019 1.1713 ±0.020 2005 2001-02 Salvatore Fiore K0K0analisys: some updates

  10. SidebandsSideboxes To better understand MC-data agreement, evaluated on the sidebands of our selection variables, the comparison is now made on a 2-dim plot: Sidebox1: Unmatched invmassKK Signal region E2miss-P2miss MC data Sidebox2: Unmatched both Sidebox3: Unmatched E2miss-P2miss invmassKK Salvatore Fiore K0K0analisys: some updates

  11. MC/data ratios in sideboxes MC/data events ratios are calculated in each sidebox, before the photon cuts: Signal region: 37/43 Sidebox1: 1.539±0.023 Signal box: In agreement within 2σ with sidebox3 In agreement within 2.5σ with average ratio Sidebox3: 20% more than sidebox2 Sidebox1: 35% more than sidebox2 E2miss-P2miss Sidebox3: 1.364±0.027 Sidebox2: 1.1389±0.0098 invmassKK Average ratio: 1.2466±0.0087 Salvatore Fiore K0K0analisys: some updates

  12. Approaching signal box To better check the sideboxes, “approaching sidebands” have been used to see how the background behaves next to the signal box: Sidebox1a: 1.20±0.13 The same procedure have been applied after the photon cuts, using the full sideboxes Sidebox3a: 2.11±0.85 Sidebox2a: 1.106±0.097 Average ratio: 1.162±0.078 E2miss-P2miss invmassKK Salvatore Fiore K0K0analisys: some updates

  13. MC/data ratios overview • Before phot. • Before phot. • approaching • After phot. Adding photon cuts and approaching signal box each sidebox scales correctly Salvatore Fiore K0K0analisys: some updates

  14. Photon efficiency curve • GEANFI MC photon efficiency is optimized applying an efficiency corection through an hit-miss: some photon clusters are thus flagged as “not seen in data”. • Removing these clusters fom our Signal MC, efficiency decreases from 21.5% to 20.6% (4% reduction) • In MC bkgd, no event surviving kine cuts contains such photons: no effect on bkgd evaluation. Salvatore Fiore K0K0analisys: some updates

  15. EMC Cluster energy: MC vs data • MC-data agreement for clusters’ energy and angles has been checked: these distributions are plotted for events surviving “photon” cuts, but without applying all the kine cuts MC/data Spectra MC data E(g) (MeV) E(g) (MeV) Salvatore Fiore K0K0analisys: some updates

  16. Cluster positions: MC vs data • Theta angle distributions: • Phi angle distributions: MC data MC/data MC/data MC data Salvatore Fiore K0K0analisys: some updates

  17. Events undergoing “photon” selection The events that survive all kine cuts are (in bkgd MC) 21 ISR events phiKsKl with one radiated photon • 3 of these ISR photons reach the EMC and make a cluster • The other clusters of these 21 events are: • pions, muons, electrons reaching EMC • uncorrlated background • No FSR events among these Salvatore Fiore K0K0analisys: some updates

  18. Present status summary • 2001-2002-2005 data + MC (+2004, data only) • Signal efficiency 20.6% • Selection cuts: • Trigger requirement • EVCL: KSKL stream • Vertices:two inside a fiducial volume of 3cm radius and ±8cm in z around IP • # of tracks: two tracks attached to each vertex are required • KS invariant mass reconstructed by π+π- tracks: 4 MeV circle cut applied around KS reco mass in m(K1) vs m(K2) plane • Reconstructedm(f0,a0) < 1010MeV • E2miss-P2missbetween -300 and 300 MeV2 • Photon request: • One cluster not associated with tracks • Cluster energy compatible with missing momentum • “photon” direction compatible with KSKS (scalar meson) momentum • 0 MC bkgd events – 1 data event Salvatore Fiore K0K0analisys: some updates

  19. Present status summary The upper limit is calculated as: with: Salvatore Fiore K0K0analisys: some updates

  20. Upper Limit Scenario • Upper limit evaluation method: • We are working in a bayesian approach with flat prior (O. Helene, NIM212(1983) 319, as for Kse+e- analysis) • With today’s numbers, without accounting for MC/data ratios from the sideboxes, the U.L. scenario is: 1.7·10-8 for 2001-02-05 1.2·10-8 for 2001-02-05 + 2004 if MC04 shows no event 1.1·10-8 for 2001-02-05 + 2004 if MC04 shows 1 event 8.9·10-9 for 2001-02-05 + 2004 if MC04 shows 2 events • We expect 15% variation of these estimates once MC/data ratios are taken into account and is exactly calculated Salvatore Fiore K0K0analisys: some updates

  21. Salvatore Fiore K0K0analisys: some updates

  22. Theoretical estimates Salvatore Fiore K0K0analisys: some updates

  23. What’s next? • Selection cuts and analysis strategy are now well defined and optimized. • MC-Data agreement have been better verified and Mc/data ratios are obtained, to be used as syst. on expected bkgd • Still Waiting for 2004 MC production to include 2004 statistics: it will be ready for ferragosto’s BBQ. • Further checks: • Exact calculation of run by run using hepdb’s sqrts and cross-section shape. • Repeat UL calculation to account for MC/data ratios • Separe different contributions in the sideboxes to better explain different ratios Salvatore Fiore K0K0analisys: some updates

  24. Salvatore Fiore K0K0analisys: some updates

More Related