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Heavy flavor production in Mario Campanelli/ Geneva Why studying heavy flavor production Experimental techniques: the Tevatron and CDF triggering and and.

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Presentation on theme: "Heavy flavor production in Mario Campanelli/ Geneva Why studying heavy flavor production Experimental techniques: the Tevatron and CDF triggering and and."— Presentation transcript:

1 Heavy flavor production in Mario Campanelli/ Geneva Why studying heavy flavor production Experimental techniques: the Tevatron and CDF triggering and and tagging Exclusive charm production in D 0 /D* Heavy flavor spectroscopy Exclusive b production in J/ψ Inclusive b-jet production Inclusive bb Inclusive b/γ

2 What’s interesting in HF production at colliders kHz rates at present Tevatron energy/luminosity kHz rates at present Tevatron energy/luminosity High mass -> well established NLO calculations, High mass -> well established NLO calculations, resummation of log(pT/m) terms (FONLL) New fragmentation functions from LEP data Gluon splitting Flavor creation Leading OrderNext to Leading Order Flavor excitation g g g g Q Q other radiative corrections.. Release date of PDF  b NLO (|y|<1) (  b) < 1994 now

3 The Tevatron World’s largest hadron collider World’s largest hadron collider √s = 1.96 TeV √s = 1.96 TeV Peak lum cm -2 s -1 Peak lum cm -2 s -1 1 fb -1 delivered to experiments 1 fb -1 delivered to experiments Analyses ~ pb -1 Analyses ~ pb -1 Collected > 800 pb -1 Delivered > 1 fb -1

4 CDF II detector Calorimeter CEM lead + scint 13.4%/√E t  2% CEM lead + scint 13.4%/√E t  2% CHA steel + scint 75%/√E t  3% CHA steel + scint 75%/√E t  3%Tracking  (d0) = 40  m (incl. 30  m beam)  (d0) = 40  m (incl. 30  m beam)  (pt)/pt = 0.15 % pt  (pt)/pt = 0.15 % pt CDF fully upgraded for Run II: CDF fully upgraded for Run II: Si & tracking Si & tracking Extended calorimeters range Extended calorimeters range L2 trigger on displaced tracks L2 trigger on displaced tracks High rate trigger/DAQ High rate trigger/DAQ

5 The experimental challenge b production 3-4 orders of magnitude smaller than ordinary QCD; selected by longer lifetime b production 3-4 orders of magnitude smaller than ordinary QCD; selected by longer lifetime c slightly higher but more difficult to isolate c slightly higher but more difficult to isolate impact parameter Decay Length Primary Vertex Secondary Vertex b/c Two strategies: High-pt (so far): take unbiased prescaled triggers, identify b off-line Low-pt: use on-line impact-parameter information to trigger on hadronic decays

6 Silicon Vertex Tracker (SVT) On-line tracking reconstruction allows design of specific triggers for heavy flavors; widely used in low-pt physics, extension to high-pt under way 35  m  33  m =  47  m (resolution  beam)

7 Cross section of exclusive charm states With early CDF data: 5.8  0.3pb -1 Measure prompt charm meson production cross section Data collected by SVT trigger from 2/2002-3/2002 Measurement not statistics limited Large and clean signals:

8 Need to separate direct D and B  D decay Prompt D point back to collision point I.P.= 0 Secondary D does not point back to PV I.P.  0 Separating prompt from secondary Charm Direct Charm Meson Fractions: D 0 : f D =86.4±0.4±3.5% D* + : f D =88.1±1.1±3.9% D + : f D =89.1±0.4±2.8% D + s : f D =77.3±3.8±2.1% B  D tail Detector I.P. resolution shape measured from data in K 0 s sample. Most of reconstructed charm mesons are direct  Separate prompt and secondary charm based on their transverse impact parameter distribution. Prompt DSecondary D from B Prompt peak

9 Differential Charm Meson X-Section Calculation from M. Cacciari and P. Nason: Resummed perturbative QCD (FONLL) JHEP 0309,006 (2003) CTEQ6M PDF M c =1.5GeV, Fragmentation: ALEPH measurement Renorm. and fact. Scale: m T =(m c 2 +p T 2 ) 1/2 Theory uncertainty: scale factor P T dependent x-sections: Theory prediction:

10 Spectroscopy with SVT datasets Huge dataset in Bs and hadronic charm, best world spectroscopic measurements for many states

11 X(3872): observation The Belle observation of a mysterious new state X(3872) in J/Ψ π + π - pushed CDF to its first confirmation. The Belle observation of a mysterious new state X(3872) in J/Ψ π + π - pushed CDF to its first confirmation. Cut on M(π π)>500 MeV: 659 candidates on 3234 background, signal seen at 11.6σ. 730 candidates, M(X) = ± 0.7 (stat) ± 0.4 (sys) Г(X) = 4.9 ± 0.7 consistent with detector resolution

12 B production from J/ψ Uses μμ trigger down to pt=0 As for D case, measures both prompt production and b decays Final b cross section in agreement with NLO calculations Combined variable of mass pt and impact parameter allows distinction of the two cases

13 High-pt identification: search for secondary vertex For inclusive studies, instead of trying to identify specific b decay products, we look for a secondary vertex resulting from the decay of the b meson For inclusive studies, instead of trying to identify specific b decay products, we look for a secondary vertex resulting from the decay of the b meson Efficiency of this “b tagging” algorithm (around 40%) is taken from Monte Carlo and cross-checked with b-enriched samples (like isolated leptons)

14 Jet algorithms for inclusive studies JetClu Preclustering Preclustering Uses E t,  Uses E t,  Not infrared safe Not infrared safe Not collinear safe Not collinear safe MidPoint No preclustering No preclustering Uses p t, y Uses p t, y Adds midpoints to original seeds Adds midpoints to original seeds Infrared safe Infrared safe Good jet definition – Resolve close jets – Stable, boost invariant – Reproducible in theory – Cone based (seeded) algorithms – JetClu (RunI) – MidPoint (new RunII ) – Merging pairs of particles – Kt (recently CDF)

15 b-jet fraction b-jet fraction Which is the real b content (purity)? Extract a fraction directly from data Use shape secondary vertex mass Use shape secondary vertex mass Different P t bins to cover wide spectrum Different P t bins to cover wide spectrum Fit data to MC templates Fit data to MC templates MonteCarlo templates b non-b 98 < p T jet < 106 GeV/c

16 High p t b jet cross section High p t b jet cross section MidPoint R cone 0.7, |Y| < 0.7 MidPoint R cone 0.7, |Y| < 0.7 Pt ranges defined to have Pt ranges defined to have 99% efficiency (97% Jet05) 99% efficiency (97% Jet05) Jets corrected for det effects Jets corrected for det effects ~ 300 pb -1 Pt ~ 38 ÷ 400 GeV 20 ÷ 10% Inclusive calorimetric triggers Inclusive calorimetric triggers L3 Et > x (5,20,40,70,100) L3 Et > x (5,20,40,70,100)

17 Preliminary Data/Pythia tune A ~ 1.4 As expected from NLO/LO comparison Main sources of systematics: Main sources of systematics: Absolute energy scale Absolute energy scale B-tagging B-tagging High p t b-jet cross section High p t b-jet cross section

18 bb cross section bb cross section Calorimetric trigger Calorimetric trigger L3: reconstructed jet E t >20GeV L3: reconstructed jet E t >20GeV JetClu cone 0.7 JetClu cone 0.7 Two central jets |  |< 1.2 Two central jets |  |< 1.2 E t (1) > 30 GeV, E t (2) > 20 GeV E t (1) > 30 GeV, E t (2) > 20 GeV Energy scale corrected for detector effects Energy scale corrected for detector effects Acceptance Acceptance Trigger efficiency folded in Trigger efficiency folded in b tagging efficiency from data b tagging efficiency from data Use an electron sample to increase bjets content Use an electron sample to increase bjets content b fraction b fraction Fit to secondary vertex mass templates Fit to secondary vertex mass templates ~ 64 pb -1

19 bb cross section bb cross section Main systematics: Main systematics: Jet energy scale (~20%) Jet energy scale (~20%) b tag efficiency (~8%) b tag efficiency (~8%) UE description lowers Herwig prediction UE description lowers Herwig predictionData 34.5 ± 1.8 ± 10.5nb Pythia(CTEQ5l)  0.62nb Herwig(CTEQ5l)  0.66nb  0.58nb Better agreement with NLO MC can be reached using a multiparton generator (JIMMY) that gives better description of underlying event. Still under investigation. Further analyses going on using SVT-triggered multi-b datasets

20 b/c + γ analysis Background to Susy searches, will be used used to extract b/c Pdf’s Background to Susy searches, will be used used to extract b/c Pdf’s No event-by-event photon identification possible: only statistical separation based on shower shape in electromagnetic calorimeter No event-by-event photon identification possible: only statistical separation based on shower shape in electromagnetic calorimeter Pre-shower Detector (CPR) Central Electromagnetic Calorimeter Shower Maximum Detector (CES) Wire Chambers

21 Photon + b/c Analysis Apply further requirements off-line:  |  |<1.0  |  |<1.0 jet with secondary vertex jet with secondary vertex Determine b, c, uds contributions Determine b, c, uds contributions Subtract photon background using shower shape fits Subtract photon background using shower shape fits Et > 25 GeV So far, use Et > 25 GeV unbiased photon dataset, without jet requirements at trigger level: Studies going on using dedicated triggers based on SVT

22 γb, γc results Cross sections and ratio agree with LO predictions from MC. This measurement still largely statistics-dominated

23 Conclusions CDF has a broad program in heavy flavor production studies (not to mention decays, oscillations etc.), thanks mainly to its tracker CDF has a broad program in heavy flavor production studies (not to mention decays, oscillations etc.), thanks mainly to its tracker Main limitation is trigger and bandwidth; SVT allowed a large increase in low-pt b physics, high-pt studies mainly used unbiased triggers Main limitation is trigger and bandwidth; SVT allowed a large increase in low-pt b physics, high-pt studies mainly used unbiased triggers SVT is being upgraded for more occupancy having in mind mainly high-pt applications SVT is being upgraded for more occupancy having in mind mainly high-pt applications QCD analyses on non-upgraded SVT datasets have started, entering a new era of high-statistics high-pt b physics QCD analyses on non-upgraded SVT datasets have started, entering a new era of high-statistics high-pt b physics


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