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FNAL Academic Lectures – May, 20061 3 –Tevatron -> LHC Physics 3 –Tevatron -> LHC Physics 3.1 QCD - Jets and Di - jets 3.2 Di - Photons 3.3 b Pair Production.

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Presentation on theme: "FNAL Academic Lectures – May, 20061 3 –Tevatron -> LHC Physics 3 –Tevatron -> LHC Physics 3.1 QCD - Jets and Di - jets 3.2 Di - Photons 3.3 b Pair Production."— Presentation transcript:

1 FNAL Academic Lectures – May, 20061 3 –Tevatron -> LHC Physics 3 –Tevatron -> LHC Physics 3.1 QCD - Jets and Di - jets 3.2 Di - Photons 3.3 b Pair Production at Fermilab 3.4 t Pair Production at Fermilab 3.5 D-Y and Lepton Composites 3.6 EW Production W Mass and Width Pt of W and Z bb Decays of Z, Jet Spectroscopy 3.7 Higgs Mass from Precision EW Measurements

2 FNAL Academic Lectures – May, 20062 Kinematics - Review Initial State

3 FNAL Academic Lectures – May, 20063 Review Kinematics - II Final State

4 FNAL Academic Lectures – May, 20064 Jet Et Distribution and Composites Simplest jet measurement - inclusive jet E T. Jet defined as energy in cone, radius R. Classical method to find substructure. Look for wide angle (S wave) scattering. Limits are  ~  s.

5 FNAL Academic Lectures – May, 20065 CDF Run II – Data Reach

6 FNAL Academic Lectures – May, 20066 Dijet Et Distribution – Run I As |  3 -  4 | increases M JJ increases and the cross section decreases. The plateau width decreases as E T increases (kinematic limit)

7 FNAL Academic Lectures – May, 20067 Dijet Mass Distribution Falls as 1/M 3 due to parton scattering and ~ (1- M/  s) 12 due to structure function source distributions. Look for deviations at large M (composite variations or resonant structure due to excited quarks). Limits at Tevatron and LHC will increase as C.M. energy.

8 FNAL Academic Lectures – May, 20068 Initial, Final State Radiation The initial state has ~ no transverse momentum. Thus a 2 body final state is back- to-back in azimuth. Take the 2 highest Et jets in the 2 J or more sample. At the higher Pt scales available at the LHC ISR and FSR will become increasingly important – determined by the strong coupling constant at that Pt scale.

9 FNAL Academic Lectures – May, 20069 “Running” of  s - Measure in 3J/2J Energy below which strong interaction is strong

10 FNAL Academic Lectures – May, 200610 Excited Quark Composites q g q* Look for resonant J - J structure, with a limit ~ C.M. energy

11 FNAL Academic Lectures – May, 200611 t Channel Angular Distribution If t channel exchange describes the dynamics, then  distribution is flat - as in Rutherford scattering. Deviations at large scattering angles would indicate composite quarks.

12 FNAL Academic Lectures – May, 200612 Diphoton, CDF Run II 2--> 2 processes similar to jets. Down by coupling and source factors Also useful in jet balancing for calibration. Important SM background in Higgs searches. Must establish SM photon signals u+g-->u+  (Lecture 2) u+u-->  + 

13 FNAL Academic Lectures – May, 200613 COMPHEP – Tree Only Tevatron, 2 TeV |  | 10 GeV

14 FNAL Academic Lectures – May, 200614 B Production @ FNAL d  /dP T ~ 1/P T 3 so  (>) ~ 1/P T 2 Spectrum is as expected with P T ~ M/2, g+g --> b + b. Adjustment in b -> B fragmentation function resolves the discrepancy. Establish a b jet signal and b tagging efficiency using 1 tag to 2 tag ratio. Many LHC searches and SM backgrounds (e.g. top pairs) require b tagging.

15 FNAL Academic Lectures – May, 200615 B Production – Rapidity Distribution Note rapidity plateau which extends to  y ~ 5 at this low mass, ~ 2m b scale. At the LHC tracking and Si vertexing extends to |y| < 2.5.

16 FNAL Academic Lectures – May, 200616 B Lifetimes Use Si tracker to find decay vertices and the production vertex.  (B) ~  (b). For Bc both the b and the c quark can decay ==> shorter lifetime. At LHC establish lifetime scale.

17 FNAL Academic Lectures – May, 200617 Weak Decay Widths t -> W b G2G2 mm W Fermi theory Standard Model 2 body weak decay

18 FNAL Academic Lectures – May, 200618 Top Mass and Jet Spectroscopy- Run I D0 - lepton + jets t-->Wb W-->JJ, l

19 FNAL Academic Lectures – May, 200619 Jet Spectroscopy - Top CDF - Lepton + jets (Si or lepton tags) t-->Wb so 2 b’s in the event

20 FNAL Academic Lectures – May, 200620 tt --> Wb+Wb, W--> qq or l tt --> Wb+Wb, W--> qq or l CDF + D0 Top quark mass from data taken in the twentieth century

21 FNAL Academic Lectures – May, 200621 Top Mass @ FNAL Run I Run II

22 FNAL Academic Lectures – May, 200622 Top Production Cross Section > 100x gain in going to the LHC. The discovery at the Tevatron becomes a nasty background at the LHC. However, W-> J+J in top pair events sets the calorimeter energy scale at the LHC. Are the mass and the cross section consistent with a quark with SM couplings?

23 FNAL Academic Lectures – May, 200623 Run II Top Cross section No evidence for deviation from SM coupling of a heavy quark. At the LHC top pair events have jets, heavy flavor, missing energy and leptons. They thus serve as a sanity check that the detector is working correctly in many final state SM particles. The LHC experiments must establish a top pair sample before contemplating, for example, SUSY discoveries.

24 FNAL Academic Lectures – May, 200624 DY and Lepton Composites Drell-Yan: Falls with the source function. For ud the W is prominent, while for uu the Z is the main high mass feature. Above that mass there is no SM signal, and searches for composite leptons or sequential W’, Z’ are made. Run I

25 FNAL Academic Lectures – May, 200625 Extract V,A Coupling to Fermions F/B asymmetry allows an extraction of the A and V couplings, g A, g V of fermions to the Z at high mass – compare to SM. If a Z’ is seen at the LHC, use the F/B distribution to try to extract the A and V couplings.

26 FNAL Academic Lectures – May, 200626 Run II – DY High Mass

27 FNAL Academic Lectures – May, 200627 Run II – DY High Mass Whole “zoo” of new Physics candidates – all still null. At LHC establish muon and electron momentum scale and resolution with Z mass and width. Explore tail when backgrounds are under control.

28 FNAL Academic Lectures – May, 200628 W - High Transverse Mass Search DY at high mass for sequential W’. Mass calculated in 2 spatial dimensions only using missing transverse energy. Run I

29 FNAL Academic Lectures – May, 200629 W - SM Mass and Width Prediction W Color factor of 3 for quarks. 9 distinct dilepton or diquark final states. Mass: Width;

30 FNAL Academic Lectures – May, 200630 COMPHEP – W BR Check that the naïve estimates are confirmed in COMPHEP for W and Z into 2*x.

31 FNAL Academic Lectures – May, 200631 W,Z Production Cross Section Cross section x BR for W is ~ 4 pb for Tevatron Run II

32 FNAL Academic Lectures – May, 200632 Lumi with W, Z ? At present in Run II, using W,Z is more accurate than Lumi monitor. Use W and Z at LHC as “standard candles”. Test of trigger and reco efficiencies – cross-check minbias trigger normalization.

33 FNAL Academic Lectures – May, 200633 W and Z - Width and Leptonic B.R. Expect 1/9 ~ 0.11 Expect 9 (0.21 GeV) = 1.9 GeV

34 FNAL Academic Lectures – May, 200634 Direct W Width Measurement decay widths of 1.5 to 2.5 GeV Monte Carlo Far from the pole mass the Breit – Wigner width (power law) dominates over the Gaussian resolution

35 FNAL Academic Lectures – May, 200635 W Transverse Mass D0 and CDF: Transverse plane only. Use Z as a control sample. At large mass dominated by the BW width, since falloff is slow w.r.t the Gaussian resolution.

36 FNAL Academic Lectures – May, 200636 W Mass – Colliders, Run I Hadron WW (LEP II) production near threshold (Lecture 1 )

37 FNAL Academic Lectures – May, 200637 W Mass - All Methods Direct Precision EW measurements

38 FNAL Academic Lectures – May, 200638 I.S.R. and P TW 2-->1 has no F.S. P T. Recall Lecture 2 - charmonium production. Scale is set by the FS mass in 2 -> 1. udud W+W+ g

39 FNAL Academic Lectures – May, 200639 COMPHEP - P TW Basic 2 --> 2 behavior, 1/P T 3.. Gluon radiation from either initial quark.

40 FNAL Academic Lectures – May, 200640 Lepton Asymmetry at Tevatron

41 FNAL Academic Lectures – May, 200641 CDF – Lepton Asymmetry Positron goes in antiproton direction Electron goes in proton direction  Charge asymmetry, constrains PDF. Recall u > d at large x.

42 FNAL Academic Lectures – May, 200642 COMPHEP - Asymmetry COMPHEP generates the asymmetry in pbar-p at 2 TeV. Can use the PDF that COMPHEP has available to check PDF sensitivity. Generate your own asymmetry and look for deviations.

43 FNAL Academic Lectures – May, 200643 Z --> bb, Run I Dijets with 2 decay vertices (b tags). Look for calorimetric J-J mass distribution. Mass resolution, dM ~ 15 GeV. This exercise is practice for searches of J-J spectra such as Z’ decays into di-jets, or H decays into b quark pairs.

44 FNAL Academic Lectures – May, 200644 Run II Mass Resolution Using tracker information to replace distinct energy deposit in the calorimetry for charged particles with the tracker momentum – which is more precisely measured. Seems to gain ~ 20%. This is quite hard – at LHC we will use W->J+J in top pair events.

45 FNAL Academic Lectures – May, 200645 VV at Tevatron - W  from D0  vertex as measured at Run II is consistent with the SM, as it is at LEP II. The WW  vertex as measured at Run II is consistent with the SM, as it is at LEP II. Transverse mass in leptonic W decays with additional photon.

46 FNAL Academic Lectures – May, 200646 WW at D0 – Run II  vertex as at LEP - II Look at dileptons plus missing transverse energy. Tests the WWZ and WW  vertex as at LEP - II

47 FNAL Academic Lectures – May, 200647 WW Cross Section Measured at CDF Extrapolate to LHC energy. COMPHEP gives a D-Y WW cross section at the LHC of 72 pb. At LHC will be able to begin to explore W- W scattering independent of Higgs searches.

48 FNAL Academic Lectures – May, 200648 W Mass Corrections Due to Top, Higgs Klein- Gordon Dirac W mass shift due to top (m) and Higgs (M)

49 FNAL Academic Lectures – May, 200649 What is M H and How Do We Measure It? The Higgs mass is a free parameter in the current “Standard Model” (SM). Precision data taken on the Z resonance constrains the Higgs mass. M t = 176 +- 6 GeV, M W = 80.41 +- 0.09 GeV. Lowest order SM predicts that M Z = M W /cos  W.. Radiative corrections due to loops. Note the opposite signs of contributions to mass from fermion and boson loops. Crucial for SUSY and radiative stability. WWWW WWWW b t H W

50 FNAL Academic Lectures – May, 200650 CDF D0 Data Favor a Light Higgs

51 FNAL Academic Lectures – May, 200651 Top and W Mass and Higgs 1 s.d contours: all precision EW data A light H mass seems to be weakly favored.

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