Beauty and Charm Production at the Tevatron Donatella

Beauty and Charm Production at the Tevatron Donatella Lucchesi INFN and University of Padova Ø Introduction Ø Recent advances in theory of heavy quark production Ø Description of the detector Ø Cross sections in pp collisions Ø Conclusions Donatella Lucchesi 1

B-quark discovered - 1977 “It now appears … that there may be a fifth quark” Donatella Lucchesi 2

20 years late… 1997 b-production cross-section were still 2 X larger than QCD prediction. At that time only a small portion of b-hadron inclusive cross-section p. T>6 Ge. V had been measured. Is it a shape or normalization problem? What about charm? Donatella Lucchesi 3

The Theory Donatella Lucchesi 4

Heavy Quark Production in pp Factorization theorem: factorize physical observable into a calculable part and non-calculable but universal piece: Donatella Lucchesi 5

Parton Density Functions: PDF Uncertainties from one PDF fit do not always cover differences with other fits New PDFs with uncertainties extracted from fit to data Donatella Lucchesi 6

Evolution of PDF By 2004, recalculating the cross-section with updated PDFs increases theoretical value by almost 2 X ! Donatella Lucchesi 7

2001: KT Factorization Scheme Standard PDFs are functions of x the fraction of the momentum carried by parton longitudinal to the hadron direction. Partons also have a small transverse momentum component: Donatella Lucchesi 8

Fragmentation Functions: Db B Donatella Lucchesi 9

Recent Theory Advances § Next-to-leading-log resummation (2001): In p. QCD calculation pawers of log(p. T)/m. Q modify shape of fragmentation function p. T>>m. Q = large corrections § Moment analysis (2002): Mellin transformation into moment space: Donatella Lucchesi 10

Comparison with Run I Data - NLL Fixed order (FO) QCD NLO calculation + resummation of next-to-leading-logs (NLL) Method of moments instead of a fragmentation model better agreement with CDF and D 0 data and theory Donatella Lucchesi 11

Theory Summary üAgreement with Run I b cross-section data for p. T>5. 0 Ge. V has greatly improved without the need to invoke exotic sources of excess b quarks. Most of the improvement is due to improved treatment of experimental inputs. üBut different theoretical approaches: different factorization schemes, FONLL calculations, new methods to extract the non-perturbative part of fragmentation function. Which is the correct approach? Total cross section do not depend on the fragmentation model = powerful experimental test of QCD calculations Charm quark mass and production cross section are close to b quarks but fragmentation is very different test theory predictions Donatella Lucchesi 12

The Experiments Donatella Lucchesi 13

CDF Run II Overview Central muon detector: Prop. Chamb. Outside Central calorimeter ~5 interaction lengths 96 layers of COT: 2. 0 Silicon Vertex detector: 8 layers of 3 -D silicon Up to | |=2 s(d 0)~30 m Donatella Lucchesi 14

Measurement of J/ and b hadron Inclusive cross section Run I: b l. X from lepton triggers to measure the b cross b c section at high p. T Use also fully and partially Wreconstructed B l (i. e. B J/ K+ and B l. DX) n Run II: use the J/ from dimuon trigger to measure the cross section at lower p. T Donatella Lucchesi 15

Run I: Leptons Trigger Select muons with p. T>12 Ge. V from b Main background: punchthrough hadrons and K and decay in flight 12< p. T 17 Ge. V 17<p. T<22 Ge. V Donatella Lucchesi 16

Run II: Muon Trigger Tracks reconstructed in the COT By the Level 1 Trigger e. Xtra Fast Tracker (XFT). A match is made to hits in the muon chamber (Offline =0986± 0. 010) Can now reach p. T(J/ ) = 0 Ge. V Donatella Lucchesi 17

Counting the J/ Donatella Lucchesi 18

J/ Cross Section Donatella Lucchesi 19

J/ Production J/ , quarkonia in general: bound state non-relativistic. NRQCD LO perturbative expansion is ( 3 s v 0) as in the Color Singlet Model (CSM) + higher order ( 3 s v 4). Fragmentation process color octet matrix element dominate. CO matrix elements extracted from fits to data agree well with Run I data at high p. T BUT inclusion of CO in NRQCD leads to a prediction of increasing transverse polarization of charmonium at high p. T Need more precise measurement Reduce the systematic error on detector acceptance Donatella Lucchesi 20

Separate Hb J/ X from Total The J/ inclusive cross section include contributions from: Ø Direct production Ø Indirect production from decays of excited charmonium states such as (2 s) J/ Ø Decays of B hadrons B J/ X B hadrons have long lifetime, J/ from Hb J/ X will be displaced Donatella Lucchesi 21

Extracting the b fraction A maximun likehood fit to the flight path in the transverse plane, Lxy, used to extract the b-fraction Prompt J/ : double Gaussian = resolution function B J/ X: From MC Parameterized background Donatella Lucchesi 22

b-Production cross section To extract ds/dp. T(Hb): Count the observed number of b-hadrons in a given p. T(Hb) bin: wij is the fraction of b events in the ith p. T(Hb) from thejth p. T(J/ ) bin obtained from MC Donatella Lucchesi 23

Charm Cross Section Donatella Lucchesi 24

Silicon Vertex Trigger Secondary h. Vertex y ca De B t ng le Primary Vertex B d=impact parameter 12 f wedges + COT SVX hits XFT SVT d 0, Pt Donatella Lucchesi 25

Charm Production in Run II Analysis uses 5. 8 pb-1 of early 2002 data Challenges: Trigger and detector not full efficient at that time Efficiency is a complex Function of p. T, z, cot( ) and time Donatella Lucchesi 26

Direct Charm Production in Run II Use impact parameter of reconstructed Charm meson FD(d 0) to distinguish directly produced charm from B DX, FB(d 0) FD(d 0) = Gaussian + exponential tail from Ks FB(d 0) = double exponential from Monte Carlo Donatella Lucchesi 27

Charm Cross-Section Donatella Lucchesi 28

Charm vs Beauty Charm and Beauty meson cross section Data/Theory ratios Donatella Lucchesi 29 are consistent

Summary ü Lots of theory advances ü Total inclusive b-hadron cross sections in agreement with theoretical predictions within uncertainties ü Charm cross section in reasonable agreement with ü theory and consistent with beauty meson result ü Some misteries still around: üQuarkonia production and polarization ü X(3870) Donatella Lucchesi 30

BACKUP Donatella Lucchesi 31

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