Today, Dr. Bellis and I continued our discussion of
radioactive decay, with a particular focus on the decay modes for the B meson
and for the J/psi particle.
There are several different decay possibilities for any
single particle. For example, two possible decay modes for J/psi are J/psi
--> e+ e- and J/psi --> μ+ μ-. So, how does one know what a certain
particle will decay to? All of a particle's decay modes, the probabilities of
these decays, and everything else you could possibly need to know about a
particle are published in the wonderful 2012 Review of Particle Physics (which
has 1526 pages and a size 10 font).
One important piece of information to know about a decay mode for a particle is its branching fraction. Basically, a branching fraction is the number of particles that decay a certain way over the total number of particles that decay. The Review of Particle Physics publishes the branching fraction for each decay.
One important piece of information to know about a decay mode for a particle is its branching fraction. Basically, a branching fraction is the number of particles that decay a certain way over the total number of particles that decay. The Review of Particle Physics publishes the branching fraction for each decay.
If you have two steps in the decay process, how do
you calculate the total possibility of that decay? For example, suppose you
want to find the proportion of particles that decay from a B neutral meson to a
positive and negative pion. A B neutral meson first decays to a K neutral
meson, which then decays into the two pions. You can find the total probability
of the decay from a B neutral meson to a positive or negative pion using a simple
rule of probability: if two events are independent, then the probability of
them both occurring is the product of the probabilities of each occurring.
Therefore, to find the total branching fraction for the decay of a B neutral
meson to a charged pion, you have to multiply the branching fractions for each
separate decay together.
Using this information, I calculated the branching fractions
for three different situations. Unfortunately, I had to spend over an hour
today in the IT office at Siena since my computer wouldn't connect to the network,
so I didn't have much time to do anything else.
Great post! I love all the details and explanation.
ReplyDeleteSo cool that you are writing about the Higgs. A momentous time to discuss that topic.
To the best of your ability, please describe the axes of graphs that you include, so that we can TRY to figure out what you are writing about.
You left us hanging at the end. What are the branching functions??
Is your computer all connected now? (Reading these in chronological order.)