Exam 39: Elementary Particle Physics

The proton beam at the Large Hadron Collider (LHC)at CERN can reach a luminosity of 10³⁴ cm^-2s^-1 (this means that in a 1 cm² area,10³⁴ protons encounter each other every second).A cross section for collisions of the order of 1 pb (picobarn)provided evidence of the Higgs boson.If the accelerator runs without interruption,approximately how many of these Higgs events can one expect in one year at the LHC?

Which of the following particles has a quark content of uud?

Which of the following particles does not have an integer spin?

Considering only the three lightest quarks,u,d,s,of all the possible combinations of baryons one can make,what fraction have non-zero strangeness?

According to most Grand Unified Theories,the lifetime of a proton is

Which of the following particles has a quark content of udd?

Determine the approximate minimum energy of a photon if a probing distance of 1.3 * 10⁴ fm is desired.

Which particle below has the smallest mass?

An electron (m=9.11 * 10^-31 kg)interacts with a positron and a single photon is emitted.Find the smallest possible frequency for this photon.

What is the electric charge of a particle with a quark content of dsb?

Protons with kinetic energy of 1.6 MeV scatter off a lead (Pb)nuclei in a foil target.Each Pb nucleus contains 82 protons.If both the incoming protons and the Pb nuclei can be treated as point objects,what is the differential scattering cross section for the protons to scatter off the Pb nuclei at an angle of 25 ^$\circ$ from their initial velocity?

Of the fundamental bosons,which has the smallest mass?

If a newly discovered boson has a maximum range of 7.1 * 10^-17 m,a spin of 0 and zero electrical charge,what is its mass?

Considering only the four lightest quarks,u,d,s,c,of all the possible combinations of mesons one can make,what proportion have strangeness 1?

What is the maximum range of the Higgs boson? The Higgs has a spin of 0,a mass of 125 GeV/c² (2.23 * 10^-25 kg)and zero electrical charge.

What is the correct expression for the Planck temperature?

Two particles interact through the weak force by exchanging a Z boson,which has a rest mass of 91 GeV/c².If energy fluctuations given by the Heisenberg uncertainty principle which produced the Z boson allow it to exist only for short times,estimate the maximum range of the weak force.

Protons scatter off a lead (Pb)nuclei in a foil target.Each Pb nucleus contains 82 protons.If both the incoming protons and the Pb nuclei can be treated as point objects and the differential scattering cross section for the protons to scatter off the Pb nuclei at an angle of 25 ^$\circ$ relative to their initial velocity is 3.2 *10^-26 m²/sr,what is the initial kinetic energy of the protons?

According to the standard model of particle physics,what conservation laws,if any,are violated in the nuclear reaction ?

The order of magnitude of the background radiation intensity at the end of the radiation-dominated era (10¹¹ s)was