Video Transcript
A charmed lambda baryon is a baryon
with the composition udc. What is the charm of the charmed
lambda baryon?
Alright, in this exercise, we’re
considering a baryon. This is a particle made up of
exactly three quarks, represented by this symbol. We want to calculate the charm of
this baryon. And it turns out that we don’t need
to recognize this symbol or even know its name in order to calculate this charm. That’s because the charm of a given
particle is affected only by the number of charm quarks and charm antiquarks it may
possess. As long as we know the quarks a
particle is made up of then, we can calculate its overall charm.
And in this case, we’re told the
three quarks making up this baryon are the up quark, the down quark, and one charm
quark. Our rule for calculating charm
tells us that for every charm quark that contributes a charm of positive one to a
particle and every charm antiquark contributes a charm of negative one. This baryon, we see, doesn’t have
any charm antiquarks, but it does have a charm quark. That by itself contributes a charm
of positive one. The up and the down quark, on the
other hand, don’t affect the charm of this particle. If we say that the total charm of
our baryon is capital C, then this is equal to the charm of our up quark plus the
charm of our down quark plus that of our charm quark. This is positive one, so that’s our
answer for the charm of the charmed lambda baryon.
