What are the quark combinations that can form (a) a neutron,...

Key Concepts

Antiquarks and Antibaryons

Antiquarks are the corresponding antiparticles to quarks, having opposite electric charge and other quantum numbers. When three antiquarks combine, they form an antibaryon. The study of antibaryons involves considering how the properties reverse relative to their matter counterparts, maintaining conservation laws such as baryon number in interactions.

Quantum Numbers and Flavor Composition

The composition of hadrons is regulated by quantum numbers such as electric charge, baryon number, strangeness, and isospin. These quantum numbers must be conserved in particle interactions, and they are determined by the specific arrangement of quark flavors. This concept is crucial for understanding why different particles, even with similar quark constituents, can have distinct identities due to differences in their internal quantum configurations.

Baryons

Baryons are a class of hadrons comprised of three quarks bound together by the strong interaction. Their properties, such as electric charge and baryon number, arise from the specific combination of quark flavors used. Understanding baryon composition involves ensuring that the combined quantum numbers, like charge and spin, match the observed properties of the particle.

Quarks

Quarks are the elementary particles that serve as the fundamental building blocks of hadrons. They come in different types or flavors (such as up, down, and strange) and carry fractional electric charges. Their intrinsic properties, including spin and color charge, determine how they combine to form composite particles.

Transcript

00:01 So in this problem, we're just figuring out what the core combinations are that form these different particles.

00:08 So we have the neutron, the antineutron, neutral lambda, and the anti -neutral sigma.

00:15 Or anti -sigma neutral.

00:18 I wrote the rest mass energies next to them.

00:22 The reason i did that is because i'm just going to say out front that.

00:28 Um, so charm bottom top quarks are too heavy.

00:40 Uh, they don't, we're not talking about heavy versions of, of this stuff.

00:46 So, uh, all of our answers are going to be up, uh, in terms of up, down and strangeness quirks.

00:57 So, uh, this just as well as looking up the, on, on, uh, i think table 43 -2, dash two, the, the, uh, the properties.

01:10 Of each of these particles and then just trying to use the other table for the quark fractional properties and add up to match them.

01:20 So neutron has spin one half.

01:31 It has barion number plus one, left on number is zero.

01:44 Strangeness is zero, charge is zero.

01:51 So let's see.

01:52 We need barione number.

01:55 Number to be positive and we see so fractures one -thirds we're going to need three quarks they're all positive and then we need them the charges to cancel out so the down quarks have negative one -third and the you know if we have two of those and an up quark would be positive two -thirds and then that that would cancel out so so d -du so, barrenum number there would be one -third plus one -third plus one -third equals positive one -chek.

02:50 Q would be minus one -third, minus because the down, so minus minus one -third, and up is positive one -third, which equals zero.

03:07 So that works.

03:08 And then the lepton number in strangeness are zero.

03:15 So the neutron should be, or a valid chart, core combination, at least would be dde, you down, down, up.

03:25 So that wants the anti -neutron.

03:31 So the charge is still zero, but the barrier number is negative one instead of positive one.

03:40 So to get that, you just reverse everything.

03:50 If you do these, it's two anti -downs and anti -up.

03:54 Charge is still going to be zero, but then the barrier number will be negative one.

04:00 So if you write then b, that's minus one -third, minus, one -third minus, one -third equals minus one -third -one, charge become so the anti down is plus one three but then the anti up is minus two three so that equals zero and then strangeness um leptown number is zero uh same same thing up there so then we have the lambda zero so this has this particle as b this baron number is positive one strangeness is minus one.

05:18 Charge for that one is zero.

05:22 Lepton number is zero.

05:28 So let's see.

05:28 So we need a strangeness.

05:33 So let's do it this way.

05:48 So we need negative one strangeness value.

05:52 So the barion number for the strangeness corpus plus one three and the charge is minus one three.

06:09 So we need the charge to go to zero.

06:16 So we're going to need a two -thirds charge and a one -thirds charge...