1. FNAL Academic Lectures - May, 20061 High P T Hadron Collider Physics Outline 1 - The Standard Model and EWSB 2 - Collider Physics 3 - Tevatron Physics QCD b and t Production EW Production and D-Y

2. FNAL Academic Lectures - May, 20062 Backup Text

3. FNAL Academic Lectures - May, 20063 UnitsUnits

4. 4 Tools Needed (will use both during lecture demonstrations) ( Google them all – also Ghostview and Acrobat reader )

5. FNAL Academic Lectures - May, 20065 COMPHEP – Models and Particles Can edit the couplings – e.g. ggH Use SM Feynman gauge Watch for LOCK

6. FNAL Academic Lectures - May, 20066 COMPHEP - Process 1-> 2,3 1-> 2,3,4 1,2 ->3,4 1,2 ->3,4,5 1,2-> 3,4,5,6 (slow) *x options No 2 -> 1

7. FNAL Academic Lectures - May, 20067 COMPHEP –Simpson, BR Find simple 2- >2. Graphs (with menu) Results can be written in.txt files Several PDF, p and pbar, Check stability of results

8. FNAL Academic Lectures - May, 20068 COMPHEP - Cuts May be needed to avoid poles or to simulate experimental cuts, e.g. rapidtiy or mass or Pt.

9. FNAL Academic Lectures - May, 20069 COMPHEP - Cuts

10. FNAL Academic Lectures - May, 200610 COMPHEP - Vegas Full matrix element calculation – interference. Watch chisq approach 1. Setup plots, draw them and write them.

11. FNAL Academic Lectures - May, 200611 COMPHEP - Decays Strictly tree level. Does not do “loops” or “box” diagrams. Explore this very useful tool. If there are problems bring them to the class and we’ll try to fix them.

12. FNAL Academic Lectures - May, 200612 1 - The SM and EWSB 1.1 The Energy Frontier 1.2 The Particles of the SM 1.3 Gauge Boson Masses and Couplings 1.4 Electroweak Unification 1.5 The Higgs Mechanism for Bosons and Fermions 1.6 Higgs Interactions and Decays

13. FNAL Academic Lectures - May, 200613 Historically HEP has advanced with machines that increase the available C.M. energy. The LHC is designed to cover the allowed Higgs mass range. Colliders give maximum C.M. energy. The Energy Frontier

14. FNAL Academic Lectures - May, 200614 The Standard Model of Elementary Particle Physics Matter consists of half integral spin fermions. The strongly interacting fermions are called quarks. The fermions with electroweak interactions are called leptons. The uncharged leptons are called neutrinos. The forces are carried by integral spin bosons. The strong force is carried by 8 gluons (g), the electromagnetic force by the photon (  ), and the weak interaction by the W + Z o and W -. The g and  are massless, while the W and Z have ~ 80 and 91 GeV mass respectively. J = 1 g, , W +,Z o,W - Force Carriers J = 1/2 udud cscs tbtb e   Q/e= 2/3 -1/3 1010 Quarks Leptons J = 0 H

15. FNAL Academic Lectures - May, 200615 Gravity – Hail and Farewell Ignore gravity. However, gravity is a precursor gauge theory which is non-Abelian. The gauge quanta are “charged”  non-linearity. The gravity field carries energy, or mass. Therefore, “gravity gravitates”. This is also true of the strong force (gluons are colored) and the weak force (W,Z carry weak charge). The photon is the only gauge boson which is uncharged.

16. FNAL Academic Lectures - May, 200616 How do the Z and W acquire mass and not the photon? How do the Z and W acquire mass and not the photon? Gravity - Physics is the same in any local general coordinate system --> metric tensor or spin 2 massless graviton coupled universally to mass = G N. Electromagnetism - Physics is the same regardless of wave function phase assigned at each local point --> massless, spin = 1, photon field with universal coupling = e These are “gauge theories” where local invariance implies massless quanta and specifies a universal ( G N, e ) coupling of the field to matter. Strong interactions are mediated by massless “gluons” universally coupled to the “color charge” of quarks = g s. Weak interactions are mediated by massive W +,Z,W - universally coupled to quarks and leptons. g W sin  W = e. How does this “spontaneous electroweak symmetry breaking” occur? (Higgs mechanism)

17. FNAL Academic Lectures - May, 200617 Lepton Colliders - LEP Z peak L and R leptons have different couplings to the Z. There is Z- photon interference which leads to a F/B asymmetry. A way to measure the Weinberg angle. g W measured from muon decay.

18. FNAL Academic Lectures - May, 200618 Field Theory Classical Special Relativity Lagrangian density, P is an operator Classical gauge replacement Quantum gauge replacement

19. FNAL Academic Lectures - May, 200619 WW in e+e- Collisions Test of self-coupling of vector bosons. There are s channel Z and photon diagrams, and t channel neutrino exchange. Test of VVV couplings. In COMPHEP play with the Breit-Wigner option as s dependence of the cross section depends crucially on the W width – i.e. technique to measure W width..

20. FNAL Academic Lectures - May, 200620 Simpson –Angular Dist Cross section without neutrino exchange in the t channel. Note divergent C.M. energy dependence – voilates unitarity.

21. FNAL Academic Lectures - May, 200621 WW Cross Section at LEP COMPHEP point shown. Proof that the WWZ triple gauge boson coupling is needed and that there are interfering amplitudes that themselves violate initarity.

22. FNAL Academic Lectures - May, 200622 WW  at LEP Probe of quartic couplings. LEP data confirms SM WWAA, WWZA Cross section in COMPHEP with all final state bosons having Pt > 5 GeV is 0.36 pb

23. FNAL Academic Lectures - May, 200623 ZZ at LEP SM has only the single Feynman diagram. There are no relevant triple or quartic couplings – in the SM. Use the data to set limits on couplings beyond the SM.

24. FNAL Academic Lectures - May, 200624 e+e- Cross Sections WW, ZZ, and WW  are seen at LEPII. At even higher C.M. energies, WWZ and ZZZ are produced - indicating triple and quartic V couplings. New channels open up at the proposed ILC. Try a few (red dots) processes yourself…..

25. FNAL Academic Lectures - May, 200625 ILC Process - Example Cross section ~ 1 fb at 500 GeV in COMPHEP. Approximate agreement with full calculation.

26. FNAL Academic Lectures - May, 200626 The Higgs Boson Postulated Potential Lagrangian density Minimum at a non-zero vev “cosmological term” This is Landau-Ginzberg superconductivity – much too simple?

27. FNAL Academic Lectures - May, 200627 How the W and Z get their Mass Covariant derivative contains gauge fields W,Z. Suppose an additional scaler field  exists and has a vacuum expectation value. Quartic couplings give mass to the W and Z, as required by the data [ V(r) ~e(exp(-r/ )/r) - weak at large r, strength e at small r].

28. FNAL Academic Lectures - May, 200628 Numerical W, Z Mass Prediction The masses for the W and Z are specified by the coupling constants. G comes from beta decays or muon decay.

29. FNAL Academic Lectures - May, 200629 Higgs Decays to Bosons Field excitations ==> interactions with gauge bosons VVH, VVHH, VVV, VVVV Higgs couples to mass. Photons and gluons are massless to preserve gauge symmetry unbroken. Thus there is no direct gluon or photon coupling.

30. FNAL Academic Lectures - May, 200630 ZZH Coupling and ILC Production ILC at 500 GeV C.M. Higgs production by off shell Z production followed by H radiation, Z* - >Z+H.

31. FNAL Academic Lectures - May, 200631 Higgs Coupling to Fermions The fermions are left handed weak doublets and right handed singlets. A mass term in the Lagrangian, is then not a weak singlet as is required. A Higgs weak doublet is needed, with Yukawa coupling, Yukawa Mass from Dirac Lagrangian density Fermion weak coupling constant

32. FNAL Academic Lectures - May, 200632 Higgs Decay to Fermions The threshold factor is for P wave,  2l+1 since scalar decay into fermion pairs occurs in P wave due to the intrinsic parity of fermion pairs. The Higgs is poorly coupled to normal (light) matter g t ~ g W (m t / M W )/  2 ~ 1.0, so top is strongly coupled to the Higgs.

33. FNAL Academic Lectures - May, 200633 The Higgs Decay Width The Higgs decay width,  scales as M H 3. Thus at low mass, the detector defines the effective resonant width and hence the time needed to discover a resonant enhancement. At high masses, the weak interactions become strong and  /M ~ 1.

34. FNAL Academic Lectures - May, 200634 Higgs Width - WW + ZZ Higgs decays to V V have widths  ~ M 3 Try this as a COMPHEP example

35. FNAL Academic Lectures - May, 200635 Higgs Width Below ZZ Threshold Below ZZ threshold, decays can occur in the tails of the Breit Wigner Z resonance, with  ~ 2.5 GeV, M ~ 91 GeV. This compares to the width to the heaviest quark, b at a Higgs mass of ~ 150 GeV. Means that W*W is an LHC strategy.

36. FNAL Academic Lectures - May, 200636 Early LHC Data Taking We have seen that the Higgs couples to mass. Thus, the cross section for production from gluons or u, d quarks is expected to be small. Therefore, it is a good strategy to prepare for LHC discoveries by establishing credibility. The SM predictions, extrapolated from the Tevatron, should first be validated by the LHC experimenters.

37. FNAL Academic Lectures - May, 200637 Vector Bosons and Forces The 4 forces appear to be of much different strength and range. We will see that this view is largely a misperception.

38. FNAL Academic Lectures - May, 200638 2 - Collider Physics 2 - Collider Physics 2.1 Phase space and rapidity - the “plateau” 2.2 Source Functions - protons to partons 2.3 Pointlike scattering of partons 2.4 2-->2 formation kinematics 2.5 2--1 Drell-Yan processes 2.6 2-->2 decay kinematics - “back to back” 2.7 Jet Fragmentation

39. FNAL Academic Lectures - May, 200639 Kinematics - Rapidity One Body Phase Space NR Relativistic Rapidity If transverse momentum is limited by dynamics, expect a uniform distribution in y Kinematically allowed range in y of a proton with P T =0

40. FNAL Academic Lectures - May, 200640 Rapidity “Plateau” Monte Carlo results are homebuilt or COMPHEP - running under Windows or Linux Region around y=0 (90 degrees) has a “plateau” with width  y ~ 6 for LHC LHC

41. FNAL Academic Lectures - May, 200641 Rapidity Plateau - Jets For ET small w.r.t sqrt(s) there is a rapidity plateau at the Tevatron with  y ~ 2 at E T < 100 GeV.

42. FNAL Academic Lectures - May, 200642 Parton and Hadron Dynamics For large E T, or short distances, the impulse approximation means that quantum effects can be ignored. The proton can be treated as containing partons defined by distribution functions. f(x) is the probability distribution to find a parton with momentum fraction x. Proceed left to right

43. FNAL Academic Lectures - May, 200643 The “Underlying Event” The residual fragments of the pp resolve into soft - P T ~ 0.5 GeV pions with a density ~ 5 per unit of rapidity (Tevatron) and equal numbers of  +  o  -. At higher P T, “minijets” become a prominent feature s dependence for P T < 5 GeV is small

44. FNAL Academic Lectures - May, 200644 COMPHEP - Minijets p-p at 14 TeV, subprocess g+g->g+g, cut on Ptg> 5 GeV. Note scale is mb/GeV

45. FNAL Academic Lectures - May, 200645 Minijets - Power Law? The very low P T fragments change to “minijets” - jets at “low” P T which have mb cross sections at ~ 10 GeV. The boundary between “soft, log(s)” physics and “hard scattering” is not very definite. Note log-log, which is not available in COMPHEP – must export the histogram pp(g+g) -> g + g

46. FNAL Academic Lectures - May, 200646 The Distribution Functions Suppose there was very weak binding of the u+u+d “valence” quarks in the proton. But quarks are bound,. Since the quark masses are small the system is relativistic - “valence” quarks can radiate gluons ==> xg(x) ~ constant. Gluons can “decay” into pairs ==> xs(x) ~ constant. The distribution is, in principle, calcuable but not perturbatively. In practice measure in lepton-proton scattering. x ~ 1/3, f(x) is a delta function

47. FNAL Academic Lectures - May, 200647 Radiation - Soft and Collinear P (1-z)P ,k The amplitude for radiation of a gluon of momentum fraction z goes as ~ 1/z. The radiated gluon will be ~ collinear -  ~ k ==>  ~ 0. Thus, radiated objects are soft and collinear. Cherenkov relation

48. FNAL Academic Lectures - May, 200648 COMPHEP, e+t->e+t+A Use heavy quark as a source of photons – needed to balance E,P. See strong forward (electron- photon) peak.

49. FNAL Academic Lectures - May, 200649 Parton Distribution Functions “valence” “sea” gluons In the proton, u and d quarks have largest probability at large x. Gluons and “sea” anti- quarks have large probability at low x. Gluons carry ~ 1/2 the proton momentum. Distributions depend on distance scale (ignore).

50. FNAL Academic Lectures - May, 200650 Proton – Parton Density Functions g dominates for x < 0.2 At large x, x > 0.2, u dominates over d and g. “sea” dominates for x < 0.03 over valence. Points are simple xg(x) parametrization.

51. FNAL Academic Lectures - May, 200651 2-->2 Formation Kinematics E.g. for top quark pairs at the Tevatron, M ~ 2M t ~ 350 GeV. ~  ~350/1800 ~ 0.2 Top pairs produced by quarks. x1x1 x2x2

52. FNAL Academic Lectures - May, 200652 Linux COMPHEP g + g->g + g with Pt of final state gluons > 50 GeV at 14 TeV p-p n.b. To delete diagrams use d, o to turn them back on one at a time Cross section is 0.013 mb (very large) Write out full events – but no fragmentation. COMPHEP does not know about hadrons.

53. FNAL Academic Lectures - May, 200653 gg -> gg in Linux COMPHEP Note the kinematic boundary, where ~ 0.007 is the y=0 value for x1=x2 for M = 100, C.M. = 14000.

54. FNAL Academic Lectures - May, 200654 CDF Data – DY Electron Pairs DY Plateau x1,x2 at Z mass ~ 0.045

55. FNAL Academic Lectures - May, 200655 The Fundamental Scattering Amplitude

56. FNAL Academic Lectures - May, 200656 Pointlike Parton Cross Sections Pointlike partons have Rutherford like behavior  ~  (  1  2 )|A| 2 /s s,t,u are Mandelstam variables. |A| 2 ~ 1 at y=0.

57. FNAL Academic Lectures - May, 200657 Hadronic Cross Sections To form the system need x 1 from A and x 2 from B picked out of probability distributions with the joint probability P A P B to form a system of mass M moving with momentum fraction x. C is a color factor (later). The cross section is  ~ (d  /dy) y=0  y. The value of  y varies only slowly with mass ~ ln(1/M)

58. FNAL Academic Lectures - May, 200658 2-->2 and 2-->1 Cross Sections “scaling” behavior – depends only on  and not M and s separately

59. FNAL Academic Lectures - May, 200659 DY Formation: 2 --> 1 At a fixed resonant mass, expect rapid rise from “threshold” -  ~ (1-M/  s) 2a - then slow “saturation”.  W ~ 30 nb at the LHC

60. FNAL Academic Lectures - May, 200660 DY Z Production – F/B Asymmetry CDF – Run I The Z couples to L and R quarks differently -> parity violating asymmetry in the photon-Z interference.

61. FNAL Academic Lectures - May, 200661 F/B Asymmetry Coupling of leptons and quarks to Z specified in SM by gauge principle. Coupling to L and R fermions differs => P violation ~ R-L coupling. Predict asymmetry, A ~ I 3 /Q. Thus, A for muons = 1, that for u quarks is 3/2, while for d quarks it is 3.

62. FNAL Academic Lectures - May, 200662 COMPHEPCOMPHEP At 500 GeV the asymmetry is large and positive – here not p-p but u-U

63. FNAL Academic Lectures - May, 200663 COMPHEP - Assym Option in “Simpson” to get F/B asymmetry in COMPHEP

64. FNAL Academic Lectures - May, 200664 DY Formation of Charmonium Cross section =  ~  2  (2J+1)/M 3 for W, width ~ 2 GeV,  = 47 nb. For charmonium, width is 0.000087 GeV, and estimate cross section in gg formation as 34 nb. The P T arises from ISR and intrinsic parton transverse momentum and is only a few GeV, on average. Use for lepton momentum scale and resolution. g g 

65. FNAL Academic Lectures - May, 200665 Charmonium Calibration Cross section in |y|<1.5 is ~ 800 nb at the LHC. Lepton calibration – mass scale, width?

66. FNAL Academic Lectures - May, 200666 Upsilon Calibration Cross section * BR about 2 nb at the LHC. Resolve the spectral peaks? Mass scale correct?

67. FNAL Academic Lectures - May, 200667 ZZ Production vs CM Energy VV production also has a steep rise near threshold. There is a 20 fold rise from the Tevatron to the LHC. Measure VVV coupling. ZZ has ~ 2 pb cross section at LHC. Not much gain in using anti-protons once the energy is high enough that the gluons or “sea” quarks dominate.

68. FNAL Academic Lectures - May, 200668 WWZ – Quartic Coupling Not accessible at Tevatron. Test quartic couplings at the LHC.

69. FNAL Academic Lectures - May, 200669 Jet-Jet Mass, 2 --> 2 Expect 1/M 3 behavior at low mass. When M/  s becomes substantial, the source effects will be large. E.g. for M = 400 GeV, at the Tevatron, M/  s=0.2, and (1-M/  s) 12 is ~ 0.07.

70. FNAL Academic Lectures - May, 200670 Jets - 2 TeV- |y|<2 E T ~ M/2 for large scattering angles. 1/M 3 [1-M/  s] 12 behavior

71. FNAL Academic Lectures - May, 200671 COMPHEP Linux

72. FNAL Academic Lectures - May, 200672 Scaling ? Tevatron runs at 630 and 1800 GeV in Run I. Test of scaling in inclusive jet production. Expect a function of only in lowest order.

73. FNAL Academic Lectures - May, 200673 Direct Photon Production Expect a similar spectrum with a rate down by ratio of coupling constants and differences in u and g source functions.  /  s ~14 u/g~6 at x~0.

74. FNAL Academic Lectures - May, 200674 D0 Single Photon Process dominated by q + g – a la Compton scattering. COMPHEP – 2 TeV p-p

75. FNAL Academic Lectures - May, 200675 2--> 2 Kinematics - “Decays” x 1 x 2 x,y,M y 3, y 4 y*,  * Formation System Decay CM Decay The measured values of y 3, y 4 and E T allow one to solve for the initial state x 1 and x 2 and the c.m. decay angle.

76. FNAL Academic Lectures - May, 200676 COMPHEP - Linux g+g-> g+ g, in pp at 14 TeV with cut of Pt of jets of 50 GeV. See a plateau for jets and the t channel peaking. Want to establish jet cross section, angular distributions and to look at jet “balance” – missing Et distribution in dijet events. MET angle ~ jet azimuthal angle and no non-Gaussian tails.

77. FNAL Academic Lectures - May, 200677 Parton-->Hadron Fragmentation For light hadrons (pions) as hadronization products, assume k T is limited (scale ~ . The fragmentation function, D(z) has a radiative form, leading to a jet multiplicity which is logarithmic in E T Plateau widens with s, ~ln(s)

78. FNAL Academic Lectures - May, 200678 CDF Analysis – Jet Multiplicity Different Cone radii Jet cluster multiplicity within a cone increases with dijet mass as ~ ln(M).

79. FNAL Academic Lectures - May, 200679 Jet Transverse Shape There is a “leading fragment” core localized at small R w.r.t. the jet axis - 40% of the energy for R< 0.1. 80% is contained in R < 0.4 cone

80. FNAL Academic Lectures - May, 200680 Jet Shape - Monte Carlo Simple model with zD(z) ~ (1-z) 5 and ~ 0.72 GeV. “Leading fragment” with ~ 0.24. On average the leading fragment takes ~ 1/4 of the jet momentum. Fragmentation is soft and non-perturbative.

81. FNAL Academic Lectures - May, 200681 Low Mass LHC Rates For small x and strong production, the cross section is a large fraction of the inelastic cross section. Therefore, the probability to find a “small Pt “minijet” in an LHC crossing is not small.

82. FNAL Academic Lectures - May, 200682 V V Production - W +  The angular distribution at the parton level has a zero. The SM prediction could be confirmed with a large enough event sample. – pp at 2 TeV with Pt > 10 GeV, 0.6 pb Asymmetry somewhat washed out by the contribution of sea anti-quarks in the p and sea quarks in the anti-proton.

83. FNAL Academic Lectures - May, 200683 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

84. FNAL Academic Lectures - May, 200684 Kinematics - Review Initial State

85. FNAL Academic Lectures - May, 200685 Review Kinematics - II Final State

86. FNAL Academic Lectures - May, 200686 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.

87. FNAL Academic Lectures - May, 200687 CDF Run II – Data Reach

88. FNAL Academic Lectures - May, 200688 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)

89. FNAL Academic Lectures - May, 200689 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.

90. FNAL Academic Lectures - May, 200690 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.

91. FNAL Academic Lectures - May, 200691 “Running” of  s - Measure in 3J/2J Energy below which strong interaction is strong

92. FNAL Academic Lectures - May, 200692 Excited Quark Composites q g q* Look for resonant J - J structure, with a limit ~ C.M. energy

93. FNAL Academic Lectures - May, 200693 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.

94. FNAL Academic Lectures - May, 200694 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-->  + 

95. FNAL Academic Lectures - May, 200695 COMPHEP – Tree Only Tevatron, 2 TeV |  | 10 GeV

96. FNAL Academic Lectures - May, 200696 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.

97. FNAL Academic Lectures - May, 200697 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.

98. FNAL Academic Lectures - May, 200698 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.

99. FNAL Academic Lectures - May, 200699 Weak Decay Widths t -> W b G2G2 mm W Fermi theory Standard Model 2 body weak decay

100. FNAL Academic Lectures - May, 2006100 Top Mass and Jet Spectroscopy- Run I D0 - lepton + jets t-->Wb W-->JJ, l

101. FNAL Academic Lectures - May, 2006101 Jet Spectroscopy - Top CDF - Lepton + jets (Si or lepton tags) t-->Wb so 2 b’s in the event

102. FNAL Academic Lectures - May, 2006102 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

103. FNAL Academic Lectures - May, 2006103 Top Mass @ FNAL Run I Run II

104. FNAL Academic Lectures - May, 2006104 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?

105. FNAL Academic Lectures - May, 2006105 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.

106. FNAL Academic Lectures - May, 2006106 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

107. FNAL Academic Lectures - May, 2006107 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.

108. FNAL Academic Lectures - May, 2006108 Run II – DY High Mass

109. FNAL Academic Lectures - May, 2006109 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.

110. FNAL Academic Lectures - May, 2006110 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

111. FNAL Academic Lectures - May, 2006111 W - SM Mass and Width Prediction W Color factor of 3 for quarks. 9 distinct dilepton or diquark final states. Mass: Width;

112. FNAL Academic Lectures - May, 2006112 COMPHEP – W BR Check that the naïve estimates are confirmed in COMPHEP for W and Z into 2*x.

113. FNAL Academic Lectures - May, 2006113 W,Z Production Cross Section Cross section x BR for W is ~ 4 pb for Tevatron Run II

114. FNAL Academic Lectures - May, 2006114 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.

115. FNAL Academic Lectures - May, 2006115 W and Z - Width and Leptonic B.R. Expect 1/9 ~ 0.11 Expect 9 (0.21 GeV) = 1.9 GeV

116. FNAL Academic Lectures - May, 2006116 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

117. FNAL Academic Lectures - May, 2006117 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.

118. FNAL Academic Lectures - May, 2006118 W Mass – Colliders, Run I Hadron WW (LEP II) production near threshold (Lecture 1 )

119. FNAL Academic Lectures - May, 2006119 W Mass - All Methods Direct Precision EW measurements

120. FNAL Academic Lectures - May, 2006120 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

121. FNAL Academic Lectures - May, 2006121 COMPHEP - P TW Basic 2 --> 2 behavior, 1/P T 3.. Gluon radiation from either initial quark.

122. FNAL Academic Lectures - May, 2006122 Lepton Asymmetry at Tevatron

123. FNAL Academic Lectures - May, 2006123 CDF – Lepton Asymmetry Positron goes in antiproton direction Electron goes in proton direction  Charge asymmetry, constrains PDF. Recall u > d at large x.

124. FNAL Academic Lectures - May, 2006124 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.

125. FNAL Academic Lectures - May, 2006125 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.

126. FNAL Academic Lectures - May, 2006126 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.

127. FNAL Academic Lectures - May, 2006127 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.

128. FNAL Academic Lectures - May, 2006128 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

129. FNAL Academic Lectures - May, 2006129 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.

130. FNAL Academic Lectures - May, 2006130 W Mass Corrections Due to Top, Higgs Klein- Gordon Dirac W mass shift due to top (m) and Higgs (M)

131. FNAL Academic Lectures - May, 2006131 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

132. FNAL Academic Lectures - May, 2006132 CDF D0 Data Favor a Light Higgs

133. FNAL Academic Lectures - May, 2006133 Top and W Mass and Higgs 1 s.d contours: all precision EW data A light H mass seems to be weakly favored.