Top-Antitop Production at Hadron Colliders

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Top-Antitop Production at Hadron Colliders

Top Quark

With a mass of m t = 173.1 ± 1.3 GeV, the TOP quark (the up-type quark of the third

generation) is the heaviest elementary particle produced so far at colliders.

Because of its mass, top quark is going to play a unique role in understanding the EW

symmetry breaking ⇒ Heavy-Quark physics crucial at the LHC.

Two production mechanisms

q

t

g

t

Pair

Production

pp(¯p) → t¯t

· · · · · ·

¯q

¯t

g

¯t

Single Top

pp(¯p) → t¯b, tq ′ (¯q ′ ), tW −

q

W +

t

b

W +

t

g

t

· · · · · ·

¯q ′

¯b

q ′ (¯q ′ ) q ′ (¯q ′ )

g

W −

Top quark does not hadronize, since it decays in about 5 ·10 −25 s (one order of magnitude

smaller than the hadronization time) =⇒ opportunity to study the quark as single particle

Spin properties

Interaction vertices

Top quark mass

Decay products: almost exclusively t → W + b (|V tb | ≫ |V td |, |V ts |)

t

V tb

W +

b

HP2.3rd GGI-Florence, September 15, 2010 – p.3/25

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