Produzione e decadimenti di Produzione e decadimenti di quark pesanti a quark pesanti a

Mario Campanelli/ Mario Campanelli/ GinevraGinevra

Tecniche sperimentali:

Tevatron e CDF

trigger e tagging

Misure ad alto pT

Produzione inclusiva di b-jets

Coppie di b

Produzione di b e fotoni

Misure a basso pT

Mesoni con charm

Mesoni con charm eccitato

Sezione d’urto b in J/ψ

D->μμ

B->μμ

The TevatronThe Tevatron World’s largest hadron colliderWorld’s largest hadron collider √√s = 1.96 TeVs = 1.96 TeV Peak lum Peak lum 1.7 101.7 1032 32 cmcm-2-2 s s-1-1 (Jan (Jan

15, 2006)15, 2006) >1 fb>1 fb-1-1 delivered to experiments delivered to experiments Analyses Analyses ~ 60-400 pb~ 60-400 pb-1-1

Collected > 1.2 fb-1

Delivered > 1.4 fb-1

CDF II CDF II detectordetector

CalorimeterCalorimeter CEM lead + scint 13.4%/√ECEM lead + scint 13.4%/√Ett2%2% CHA steel + scint 75%/√ECHA steel + scint 75%/√Ett3%3%TrackingTracking (d0) = 40(d0) = 40m (incl. 30m (incl. 30m beam)m beam) (pt)/pt = 0.15 % pt (pt)/pt = 0.15 % pt

CDF fully upgraded for Run CDF fully upgraded for Run II:II:

Si & trackingSi & tracking Extended calorimeters range Extended calorimeters range L2 trigger on displaced tracksL2 trigger on displaced tracks High rate trigger/DAQHigh rate trigger/DAQ

The experimental The experimental challengechallenge

b production 3-4 orders of b production 3-4 orders of magnitude smaller than magnitude smaller than ordinary QCD; selected by ordinary QCD; selected by longer lifetimelonger lifetime

c slightly higher but more c slightly higher but more difficult to isolatedifficult 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

What’s interesting in HF production at What’s interesting in HF production at colliderscolliders

kHz rates at present Tevatron kHz rates at present Tevatron energy/luminosityenergy/luminosity

High mass -> well established High mass -> well established NLO calculations, NLO calculations, resummation of log(pT/m) terms (FONLL)

New fragmentation functions from LEP data

Gluon splittingFlavor creation

Leading Order Next to Leading Order

Flavor excitationg

g

g

g

Q

Q

other radiative corrections..

Release date of PDF

bN

LO(|y

|<1)

(b

) <1994

now

High-pt identification: High-pt identification: search for secondary vertexsearch for secondary vertex

For inclusive studies, instead For inclusive studies, instead of trying to identify specific of trying to identify specific b decay products, we look b decay products, we look for a secondary vertex for a secondary vertex resulting from the decay of resulting from the decay of the b mesonthe b meson

Efficiency of this “b Efficiency of this “b tagging” algorithm tagging” algorithm (around 40%) is taken (around 40%) is taken from Monte Carlo and from Monte Carlo and cross-checked with b-cross-checked with b-enriched samples (like enriched samples (like isolated leptons)isolated leptons)

b-jet fractionb-jet fractionWhich is the real b content Which is the real b content (purity)(purity)??Extract a fraction directly from dataExtract a fraction directly from data Use shape Use shape secondary vertex masssecondary vertex mass

Different PDifferent Ptt bins to cover wide spectrum bins to cover wide spectrum Fit data to MC templatesFit data to MC templates

MonteCarlo templatesb

non-b

98 < pTjet < 106 GeV/c

High pHigh ptt b jet cross b jet cross sectionsection

MidPointMidPoint R Rconecone 0.7, |Y| < 0.7 0.7, |Y| < 0.7 Pt ranges defined to have Pt ranges defined to have 99% 99% efficiencyefficiency ((97% 97% Jet05)Jet05)

Jets corrected for det effectsJets corrected for det effects

~ 300 pb-1

Pt ~ 38 ÷ 400 GeV

20 ÷ 10%

Inclusive calorimetric triggersInclusive calorimetric triggers L3 Et > x L3 Et > x (5,20,40,70,100)(5,20,40,70,100)

Preliminary Data/Pythia tune A ~ 1.4

As expected from NLO/LO comparison

Main sources of Main sources of systematics:systematics:

Absolute energy scaleAbsolute energy scale B-taggingB-tagging

High pHigh ptt b-jet cross b-jet cross sectionsection

bb cross bb cross sectionsection

Calorimetric triggerCalorimetric trigger L3: reconstructed jet L3: reconstructed jet

EEtt>20GeV>20GeV JetCluJetClu cone 0.7 cone 0.7 Two central jets |Two central jets ||< 1.2|< 1.2

EEtt(1) > 30 GeV, E(1) > 30 GeV, Ett(2) > 20 GeV (2) > 20 GeV Energy scale corrected for Energy scale corrected for

detector effects detector effects Acceptance Acceptance

Trigger efficiency folded inTrigger efficiency folded in b tagging efficiency from datab tagging efficiency from data

Use an electron sample to Use an electron sample to increase bjets contentincrease bjets content

b fractionb fraction Fit to secondary vertex mass Fit to secondary vertex mass

templatestemplates

~ 64 pb-

1

bb cross bb cross sectionsection Main Main systematicssystematics::

Jet energy scale (~20%)Jet energy scale (~20%) b tag efficiency (~8%)b tag efficiency (~8%)

UE description lowers UE description lowers Herwig predictionHerwig prediction

DataData 34.5 ± 1.8 ± 34.5 ± 1.8 ± 10.5nb10.5nb

Pythia(CTEQ5l)Pythia(CTEQ5l) 38.71 38.71 0.62nb 0.62nb

Herwig(CTEQ5lHerwig(CTEQ5l))

21.53 21.53 0.66nb 0.66nb

MC@NLOMC@NLO 28.49 28.49 0.58nb 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

b/c + b/c + γγ analysis analysis Background to Susy Background to Susy

searches, will be searches, will be used used to extract used used to extract b/c Pdf’sb/c Pdf’s

No event-by-event No event-by-event photon identification photon identification possible: only possible: only statistical statistical separation based on separation based on shower shape in shower shape in electromagnetic electromagnetic calorimetercalorimeter

Pre-shower Detector (CPR)

Central Electromagnetic Calorimeter

Shower Maximum Detector (CES)

Wire Chambers

Photon + b/c Photon + b/c AnalysisAnalysis

Apply further requirements off-Apply further requirements off-line:line:

|||<1.0|<1.0 jet with secondary vertexjet with secondary vertex Determine b, c, uds Determine b, c, uds

contributions contributions Subtract photon background Subtract photon background

using shower shape fitsusing shower shape fits

So far, use Et > 25 GeV Et > 25 GeV unbiased photon dataset, without jet requirements at trigger level:

Studies going on using dedicated triggers based on SVT

γγb, b, γγc c resultsresults

Cross sections and ratio agree with LO predictions from MC.

This measurement still largely statistics-dominated

Silicon Vertex Silicon Vertex Tracker (SVT)Tracker (SVT)

On-line tracking reconstruction allows On-line tracking reconstruction allows design of specific triggers for heavy design of specific triggers for heavy flavors; widely used in low-pt physics, flavors; widely used in low-pt physics, extension to high-pt under wayextension to high-pt under way

35 m 33 m = 47 m

(resolution beam)

Two-track triggerTwo-track trigger Level 1: Level 1:

two XFT tracks with two XFT tracks with pT>2 GeVpT>2 GeV pTpT11 + pT + pT22 >5.5 GeV >5.5 GeV

Level 2:Level 2: 120 120 μμm < |dm < |d00| < 1 mm| < 1 mm for each track for each track Opening angle Opening angle 22˚̊ <| <|ΔφΔφ| < 90| < 90˚̊ Lxy > 200 Lxy > 200 μμm m

Fully hadronic decays; other trigger paths still using SVT information exist for semileptonic and leptonic channels

Cross section of exclusive Cross section of exclusive charm statescharm states

With early CDF data:With early CDF data: 5.8 5.80.3pb0.3pb-1-1

• 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:

Need to separate direct D and BD 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 Separating prompt from

secondary Charmsecondary Charm

Direct Charm Meson Fractions:Direct Charm Meson Fractions:

DD00: f: fDD=86.4±0.4±3.5=86.4±0.4±3.5%%

D*D*++: : ffDD=88.1±1.1±3.9%=88.1±1.1±3.9%

DD++: f: fDD=89.1±0.4±2.8%=89.1±0.4±2.8%

DD++ss: f: fDD=77.3±3.8±2.1%=77.3±3.8±2.1%

BD tail

Detector I.P. resolution shape measured

from data in K0s sample.

Most of reconstructed charm mesons are direct

Separate prompt and secondary

charm based on their transverse

impact parameter distribution.

Prompt D Secondary D from B

Promptpeak

Differential Charm Meson Differential Charm Meson X-Section X-Section

Calculation from M. Cacciari and P. Nason:

Resummed perturbative QCD (FONLL)

JHEP 0309,006 (2003)

CTEQ6M PDF

Mc=1.5GeV,

Fragmentation: ALEPH measurement

Renorm. and fact. Scale: mT=(mc2+pT

2)1/2

Theory uncertainty: scale factor 0.5-2.0

PT dependent x-sections:

Theory prediction:

G3X track calibration G3X track calibration (Gen4)(Gen4)

To perform high-precision spectroscopy measurements To perform high-precision spectroscopy measurements energy loss in tracker has to be properly accounted for. energy loss in tracker has to be properly accounted for.

The GEANT description of the detector material has been The GEANT description of the detector material has been used in a first time to correct for energy loss. used in a first time to correct for energy loss.

An additional layer, (20% of total passive material in the An additional layer, (20% of total passive material in the silicon tracking system) has been added inside the inner silicon tracking system) has been added inside the inner shell of the COT to remove the dependence of the J/shell of the COT to remove the dependence of the J/ΨΨ on on pT.pT.

Also the value of the magnetic field has been recalibratedAlso the value of the magnetic field has been recalibrated Calibration tested on DCalibration tested on D00

K.Anikeev, G.Bauer, I.Furic, S.Gromoll, A.Korn, I.Kravchenko,Ch.Paus, A.Rakitin, J.Tseng

Kalman track Kalman track calibration (Gen5)calibration (Gen5) With tracking reconstruction With tracking reconstruction

improvements, it became improvements, it became possible to add the additional possible to add the additional material in the much faster material in the much faster Kalman refitter.Kalman refitter.

Standard material description still inadequate; photon conversion distribution indicates extra material to be z-dependent and in several locations

M.Campanelli, E.Gerchtein

After retuning

Tests of Kalman Tests of Kalman calibrationcalibration Calibration performed on J/Calibration performed on J/ΨΨ, tested on many other , tested on many other

channels, also to check for charge asymmetrieschannels, also to check for charge asymmetries

As well as on D0 and D*-D0 mass difference

Spectroscopy with SVT Spectroscopy with SVT datasetsdatasets

Huge dataset in Huge dataset in Bs and Bs and hadronic hadronic charm, best charm, best world world spectroscopic spectroscopic measurements measurements for many statesfor many states

CDF muon system and CDF muon system and triggertrigger

Internal muon chambers Internal muon chambers ((CMUCMU) after HCAL) after HCAL

External muon chambers External muon chambers ((CMPCMP) after magnet) after magnet

eXtension muon eXtension muon chambers (chambers (CMXCMX) ) for for 0.6<0.6<ηη<1.0<1.0

Several muon-based triggers;

•J/ψ with two opposite-sign muons pT>1.5 GeV

pT1+pT2 down to zero

•Exotic triggers for CMU/CMU or CMU/CMX events

Search for Search for DD0 0 →→μμμμ in the in the TTT dataset TTT dataset GIM-suppressed (GIM-suppressed (BR ≈ 10BR ≈ 10-13-13), up to 10), up to 10-8-8 in SUSY in SUSY

No trigger requirement on muons, since analysis No trigger requirement on muons, since analysis uses Duses D00→→ππππ for normalization, and D* for normalization, and D*→→DD00ππ, , DD00→→KKππ to determine fake muon background to determine fake muon background

Mis-id pions

Mis-id kaons

Results on Results on DD00→→μμμμ MC used to derive efficiency and acceptance MC used to derive efficiency and acceptance

corrections between pions and muons.corrections between pions and muons.εε((ππππ)/)/εε((μμμμ)) =1.13±0.04, =1.13±0.04, a(a(ππππ)/a()/a(μμμμ)) =0.96±0.02 =0.96±0.02

Additional cuts optimized maximizing Punzi function S/(1.5+√B):

|Δφ(CMU)|> 0.085 rad, |dxy|<150 μm, Lxy < 0.45 cm

Expected BG 1.8±±0.7, observed 0, limit set to 2.5 10-6 at 90% C.L.

B production from B production from J/J/ψψ sample sample

Triggers Triggers μμμμ in in J/J/ψψ mass window mass window down to down to ΣΣ pT=0 pT=0As for D case, measures both prompt As for D case, measures both prompt

production and b decaysproduction and b decays

Final b Final b cross cross section in section in agreemenagreement with t with NLO NLO calculatiocalculationsns

Combined variable of mass pt and impact parameter allows distinction of the two cases

Search for Search for Bd,Bs Bd,Bs →→μμμμ Expected SM BR: 10Expected SM BR: 10-10-10 and 3 10 and 3 10-9-9 respectively. respectively.

SUSY may enhance by 3 orders of magnitude, SUSY may enhance by 3 orders of magnitude, tantanββ66

Use both CMU-CMU and CMU-CMX events, Use both CMU-CMU and CMU-CMX events, restricting to restricting to pT>2 (2.2) GeVpT>2 (2.2) GeV and and |pT|pTμμμμ|>4 GeV|>4 GeV

Requiring Requiring LL3D3D<1 cm, (L<1 cm, (L3D3D)< 150 )< 150 μμm, 2cm, 2cττ<c<cττ<0.3 <0.3 cmcm still leaves a large combinatorial BG: still leaves a large combinatorial BG:

Likelihood methodLikelihood method

λλ=c=cττ ΔαΔα pointing angle pointing angle

between p and L between p and L

Normalization channelNormalization channel BB++→J/→J/ψψKK++ taken with same trigger and same taken with same trigger and same

requirements, plus requirements, plus pT(K)> 1 GeVpT(K)> 1 GeV.. Used as normalization and to cross-check Used as normalization and to cross-check

MC; MC; Important inacceptance ratio and likelihood Important inacceptance ratio and likelihood

efficiencyefficiency Background estimation fromBackground estimation from

Like-sign muonsLike-sign muons Events with Events with λλ<0<0 Fake-enriched sampleFake-enriched sample

ResultsResults To optimize a priori 90% C.L. upper To optimize a priori 90% C.L. upper

limit, the cut chosen is limit, the cut chosen is LLRR>0.99.>0.99. Expected BG: Expected BG: 0.81±0.12; 0.66±0.130.81±0.12; 0.66±0.13 No events found in either mass windowNo events found in either mass window

Limits sets to

BR(Bs →μμ)< 1.5 10-7

BR(Bd →μμ)< 3.9 10-8 at 90% CL

ConclusioniConclusioni CDF ha un enorme programma di fisica del b. Io CDF ha un enorme programma di fisica del b. Io

ho solo mostrato qualche esempio, Giuseppe ho solo mostrato qualche esempio, Giuseppe parlera’ domani delle attivita’ legate al mixingparlera’ domani delle attivita’ legate al mixing

In un collider adronico non si puo’ tenere tutto In un collider adronico non si puo’ tenere tutto cio’ che si vorrebbe, il trigger ha importanza cio’ che si vorrebbe, il trigger ha importanza crucialecruciale

L’SVT ha aperto l’era dei decadimenti adronici e L’SVT ha aperto l’era dei decadimenti adronici e migliorato molto le performances dei trigger migliorato molto le performances dei trigger “tradizionali” basati sui leptoni“tradizionali” basati sui leptoni

Il detector si capisce sempre meglio, misure di Il detector si capisce sempre meglio, misure di alta precisione sono possibilialta precisione sono possibili

Lezioni (forse ovvie) per LHC:Lezioni (forse ovvie) per LHC: Avere tanti trigger ridondantiAvere tanti trigger ridondanti Prendere molti dati di risonanze di riferimentoPrendere molti dati di risonanze di riferimento Usare il meno possibile il MonteCarloUsare il meno possibile il MonteCarlo