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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 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
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FNAL Academic Lectures – May, 20062 Kinematics - Review Initial State
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FNAL Academic Lectures – May, 20063 Review Kinematics - II Final State
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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.
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FNAL Academic Lectures – May, 20065 CDF Run II – Data Reach
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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)
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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.
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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.
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FNAL Academic Lectures – May, 20069 “Running” of s - Measure in 3J/2J Energy below which strong interaction is strong
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FNAL Academic Lectures – May, 200610 Excited Quark Composites q g q* Look for resonant J - J structure, with a limit ~ C.M. energy
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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.
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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--> +
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FNAL Academic Lectures – May, 200613 COMPHEP – Tree Only Tevatron, 2 TeV | | 10 GeV
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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.
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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.
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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.
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FNAL Academic Lectures – May, 200617 Weak Decay Widths t -> W b G2G2 mm W Fermi theory Standard Model 2 body weak decay
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FNAL Academic Lectures – May, 200618 Top Mass and Jet Spectroscopy- Run I D0 - lepton + jets t-->Wb W-->JJ, l
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FNAL Academic Lectures – May, 200619 Jet Spectroscopy - Top CDF - Lepton + jets (Si or lepton tags) t-->Wb so 2 b’s in the event
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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
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FNAL Academic Lectures – May, 200621 Top Mass @ FNAL Run I Run II
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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?
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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.
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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
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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.
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FNAL Academic Lectures – May, 200626 Run II – DY High Mass
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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.
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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
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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;
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FNAL Academic Lectures – May, 200630 COMPHEP – W BR Check that the naïve estimates are confirmed in COMPHEP for W and Z into 2*x.
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FNAL Academic Lectures – May, 200631 W,Z Production Cross Section Cross section x BR for W is ~ 4 pb for Tevatron Run II
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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.
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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
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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
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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.
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FNAL Academic Lectures – May, 200636 W Mass – Colliders, Run I Hadron WW (LEP II) production near threshold (Lecture 1 )
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FNAL Academic Lectures – May, 200637 W Mass - All Methods Direct Precision EW measurements
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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
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FNAL Academic Lectures – May, 200639 COMPHEP - P TW Basic 2 --> 2 behavior, 1/P T 3.. Gluon radiation from either initial quark.
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FNAL Academic Lectures – May, 200640 Lepton Asymmetry at Tevatron
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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)
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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
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FNAL Academic Lectures – May, 200650 CDF D0 Data Favor a Light Higgs
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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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