At a hadron collider running at instantaneous luminosity

PHYSICS · Multi-part · Fermi University Physics · Particle Physics & Quantum Fields · Electronics, Instrumentation & Communication · Particles, interactions and experiment

Particle Physics, Ch Detectors, event reconstruction and claiming a discovery

Problem

At a hadron collider running at instantaneous luminosity L=5.0×1033 cm−2 s−1\mathcal{L} = 5.0\times10^{33}\,\mathrm{cm^{-2}\,s^{-1}}, the product of cross section, branching ratio B(W→μν)\mathcal{B}(W\to\mu\nu) and selection efficiency for the process pp→W+X→μν+Xpp\to W + X \to \mu\nu + X is measured to be σ B ε=0.80 nb\sigma\,\mathcal{B}\,\varepsilon = 0.80\,\mathrm{nb}, where 1 nb=10−33 cm21\,\mathrm{nb} = 10^{-33}\,\mathrm{cm^2}. ((a)) Estimate the number of such events recorded during 2.02.0 hours of running. ((b)) In one recorded event the muon has transverse momentum 50 GeV/c50\,\mathrm{GeV}/c along the direction φ=0∘\varphi = 0^\circ in the plane transverse to the beam, and the combined transverse momentum of every other observed track and calorimeter cluster (the hadronic recoil) is 46 GeV/c46\,\mathrm{GeV}/c along φ=170∘\varphi = 170^\circ. Estimate the missing transverse energy of the event, and state what physical object it is attributed to.

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