A future LHC run delivers an integrated luminosity of at

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

A future LHC run delivers an integrated luminosity of

\mathcal{L}_{\rm int} = 300\,\mathrm{fb^{-1}}

\sqrt{s} = 13\,\mathrm{TeV}

. The inclusive Higgs boson production cross section is

\sigma(pp\to H) = 48\,\mathrm{pb}

, the branching ratio is

\mathcal{B}(H\to\gamma\gamma) = 2.3\times10^{-3}

, and the overall selection efficiency for the diphoton final state is

\varepsilon = 0.4

. ((a)) Estimate the number of

H\to\gamma\gamma

events expected to be reconstructed over the whole run. ((b)) In a separate event with no reconstructed leptons or photons, the only visible objects are three narrow sprays of hadrons, each measured as a single momentum, with transverse momenta

p_{\rm T} = 45\,\mathrm{GeV}/c

at azimuthal angle

\phi = 0^\circ

p_{\rm T} = 60\,\mathrm{GeV}/c

\phi = 130^\circ

, and

p_{\rm T} = 30\,\mathrm{GeV}/c

\phi = 250^\circ

(angles measured in the transverse plane, all momenta in the same plane). Estimate the missing transverse energy of this event and its direction, and state what it suggests escaped the detector unseen.

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