Video Transcript
A 𝛯 baryon is a baryon with the
composition uss. What is the strangeness of the 𝛯
baryon?
Okay, so here we’re being told
about this particle called a 𝛯 baryon. And we’re told what it’s composed
of, in particular, the types of quarks that make it up. We’re told that if we take an up
quark and then join it with a strange quark and another strange quark, then what we
have is this particle called a 𝛯 baryon and symbolized using the Greek letter
𝛯. As a side note, this superscript
zero indicates the overall relative charge of this baryon.
An up quark, we can recall, has a
relative charge of positive two-thirds times the charge of a proton, while a strange
quark has a relative charge of negative one-third e. If we add together all the relative
charges of these quarks, we get a result of zero, the relative charge of the
particle overall. But of course what we want to know
is the strangeness of this particle, and we’ll calculate that in a different
way.
Strangeness is a property of a
particle that comes down to how many strange quarks and strange antiquarks it
possesses. For every strange quark a particle
possesses, we add a strangeness of negative one to it. And then for every strange
antiquark, we add a strangeness of positive one. And then the overall strangeness of
the particle is equal to the sum of these individual strangenesses.
Let’s call the strangeness of our
𝛯 baryon capital 𝑆. And before we start counting any of
the quarks in this particle, let’s say our strangeness starts out at zero. First, we look at the up quark. And this, like all quarks other
than the strange quark, contributes nothing to strangeness. So the strangeness of our particle
is still zero at this point. Then we move on to this first
strange quark here. According to our rule, every
strange quark contributes a strangeness of negative one. So at this point, the strangeness
of our 𝛯 baryon is no longer zero, but we have negative one. And then we move on to the second
strange quark here. Just like the first one, this also
contributes a strangeness of negative one to the particle overall, so that once all
of our quarks are accounted for, we have a total strangeness for this particle of
negative two. And that’s our answer. The strangeness of a 𝛯 baryon with
zero net charge is negative two.
