Question

Particle Physics

Let's do a little particle physics. Back in the '9os there was a large electron-positron collider at CERN in Geneva, Switzerland, called the "Large electron-positron collider," or LEP for short. (This collider was broken down and rebuilt into an even larger one that runs to this day, called the "Large hadron collider" or LHC.) It was LEP that discovered the W and Z bosons, which mediate weak nuclear processes like the beta decay of free neutrons Anyway, near the end of its lifetime, it was colliding electrons and positrons together in such a way that, just before the collision, the total momentum of the electron/positron pair was approximately zero and the e nergy was Eo 209 GeV 3.35 x 10-8 J (A GeV, or giga-electron-volt, is a more convenient unit of energy in particle physics.) 1. The mass of an electron (which is equal to the mass of a positron) ism 9.11 x 10-31 kg, and the speed of light is c 3.00 x 108 m/s. Using that the energy and momentum of an electron are determined by the mass and velocity as nv 2 find the speed of the incident electron and positron. 2. Every once in a great while, the incoming electron and positron would annihilate and produce a Z boson, which would live for a short time and then decay. The Z boson has a mass GeV c2 m1.2.62 x 10-25 kg Using the conservation of energy and momentum, could the electron-positron pair make a Z boson at rest? If not, find the total energy of the electron-positron pair (not the energy above) required to make a Z 3. In quantum mechanics, even when the incident energy is more than enough to make a Z, there is a nonzero probability to make what is called a "virtual" Z boson. This is essentially because the Z boson is already unstable. Anyway, in some collisions at LEP with incident energy Eo, a virtual Z boson was made, which then decayed into a muon-antimuon pair (the muon is sort of a heavier version of an electron, and the antimuon is the muon's antiparticle). The muon and antimuon have a mass m 1.88 x 10-5 kg Using the conservation of energy and momentum, find the energy, momentum, and speed of the final muon and antimuon.

Answer 1

re: 9.11 지 tve ca 2.35x10

and ecto mave 2

hot 1531 om t1서 2