pQCD and Hadron Collider Phenomenology

2005 Summer School

C.-P. YuanMichigan State University

Tsinghua University, Beijing, China July 2005

(Revised from the lecture notes by Wu-Ki Tung)

Quantum Chromodynamics

Why does QCD play such a crucial role in High Energy Phenomenology?

• The parton picture language provides the foundation on which all modern particle theories are formulated, and all experimental results are interpreted.

• The validity of the parton picture is based empirically on an overwhelming amount of experimental evidence collected in the last 30-40 years, and theoretically on the Factorization Theorems of PQCD.

Key concepts: Ultra-violet divergences, bare Green fns, renormalization, RGE, anomalous dimensions,

renormalized G.Fs, … etc.

Analogies and correspondences (see later)

Analogies and correspondences (see later)

universal

,

extracted by global analysis

Theory

Input

Lepton-hadron Sc.

Hadron Collider Physics

hadrons

leptons, hadrons

partons, gauge bosons,

new particles

(universal) parton

Distributions

SM and New

physics

jet algorithms

hadronization models: MC

programs

frag. functions

Example: Charm Production in DIS Experiments

4-flv (M 0) calculation(ACOT):

Flavor creationFlavor excitation Overlap/subtraction

~ s ln(Q/M)

HE limit: approaches conventional ZM 4-flv LO (FE) + NLO (~ s)

Near Threshold: approx. 3-flv HQ calc.LO-FC (~ s) + O(s

2)

In the intermediate region, all three terms are needed to provide an accurate description of the physics.

Important HQ initiated Processes: Top and Higgs

Single Top Production:W

t

b

W

t

b

g

Higgs Production:

Apply it to Top Quark Phenomenology at Hadron Colliders

Tevatron and LHC

Beyond the Leading Order in QCD