Measurement of the Jet Energy Scale in the CMS experiment ... - IIHE

More documents

Recommendations

Info

4 CHAPTER 1: The Standard Model of Particle Physics1.1 Elementary Particles and Their Interactions1.1.1 Electroweak TheoryThe fundamental particles, namely quarks and leptons, which are fermions with halfintegerspin are represented by Dirac spinors ψ, that fulfill the Dirac equation 1iγ µ ∂ µ ψ = 0.In the presence of an external electromagnetic field A µ , the fermions couple to thequantum of the field, which is called the photon γ, and their interaction are describedby a Lagrangian term expressed asL inte.m = ∑ f¯ψ f iγ µ D µ ψ f ,where the sum is over all fermions and D µ is the covariant derivative defined as D µ =∂ µ + ieQA µ . In the language of group theory, the dirac spinors are representations ofthe U e.m (1) group since the Lagrangian is invariant under the gauge transformationψ → e ieQ ψ.According to Noethers’s theorem, there is a conservation law that can be associatedto this gauge symmetry. Therefore the electric charge Q, which is expressed in unitsof quantum number e, is constant during the electromagnetic interactions. The Diracspinors associated to the elementary particles and their corresponding charge are listedin Table 1.1.As expressed in Table 1.1, the leptons as well as the quarks appear in three generationswhose constituents are equal in all quantum numbers but differentiated in termsof mass. The most stable particles are the ones listed in the first generation for each ofthe two category of fermions. The elementary particles interact with the electromagneticfield via their charge, hence no interaction vertex is present between the photonand the neutrino in the Standard Model since the neutrinos are neutral fermions.In addition to the electromagnetic interactions which are formulated in a simple Lagrangianterm and can fully describe the interaction of the charged particles, there isanother kind of interaction describing the phenomena like beta decay p → n + e + ν e ,which corresponds to the physics processes containing a neutrino as one of the componentsof the interaction. This kind of interaction, known as the weak interaction,contains a heavy particle as propagator. Because of the rather massive property ofthe propagator of the weak interaction, they are difficult to be produced during aninteraction. Therefore, the weak interactions are rare within the Standard Model.In order to describe the physics of the weak interactions, an appropriate term shouldbe added to the Lagrangian. According to the experimental data, where only lefthandedfermions contribute to the weak interaction, the weak current ¯ψ νe γ µ (1 − γ 5 )ψ e1 The mass term is dropped from the Dirac equation for simplicity.
CHAPTER 1: The Standard Model of Particle Physics 5fermionsfirst generationQ( )ψe -1ψ νe 0leptonssecond generation ( )ψµ -1ψ νµ 0third generationfirst generation( )ψτ -1ψ ντ 0(ψu)+23ψ d − 1 3quarkssecond generation (ψc)+23ψ s − 1 3third generation(ψt)+23ψ b − 1 3Table 1.1: The elementary particles, being quarks and leptons, predicted by the StandardModel and observed in the experiment. The electric charge Q, associated to eachparticle is also listed.
Page 1: Vrije Universiteit BrusselFaculteit
Page 5 and 6: IntroductionThe Standard Model of p
Page 7: Chapter 1The Standard Model of Part
Page 11 and 12: CHAPTER 1: The Standard Model of Pa
Page 19 and 20: Chapter 2The CMS experiment at the
Page 21 and 22: CHAPTER 2: The CMS experiment at th
Page 33 and 34: Chapter 3Object ReconstructionThe e
Page 35 and 36: CHAPTER 3: Object Reconstruction 31
Page 51 and 52: Chapter 4Reconstructing and Selecti
Page 53 and 54: CHAPTER 4: Reconstructing and Selec
Page 59 and 60:
CHAPTER 4: Reconstructing and Selec
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Chapter 5Estimating of the Jet Ener
Page 73 and 74:
CHAPTER 5: Estimating of the Jet En
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
2χ / ndf18.76 / 7p0 9.492e-08 ±9.
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Chapter 6ConclusionThe Standard Mod
Page 133 and 134:
CHAPTER 6: Conclusion 129The method
Page 135 and 136:
Bibliography[1] M. E. Peskin and D.
Page 137 and 138:
BIBLIOGRAPHY 133[40] The ALICE Coll
Page 139 and 140:
BIBLIOGRAPHY 135[76] The CMS Collab
Page 141 and 142:
SummaryJets appear in the final sta
show all

Measurement of the Jet Energy Scale in the CMS experiment ... - IIHE

Create successful ePaper yourself

Delete template?

Save as template?