0
$\begingroup$

I can't seem to find an answer to this. For a given configuration, say for a Hydrogen atom: the proton has properties which give it a positive charge. This is a known truth.

Now lets take Hydrogen's antiparticle (anti-Hydrogen) and compare the structure - All the information I've found so far only points to a difference in charge without explaining the structure that governs the charge of the proton or anti-proton.

I'm trying to understand what structural differences define a particle as being either matter or antimatter.

Can anyone help with this?

Improve this question
$\endgroup$
4
  • $\begingroup$ We just add up the charges of the valence constituents. The charge of each type of anti-quark is -1 times the charge of the respective quark so of course the anti-whateverhadron has the opposite charge of the whateverhadron. $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Oct 9, 2014 at 3:54
  • $\begingroup$ Thanks @dmckee for answering. Of course this makes sense. What governs the quark's state though? How does it have a charge in the first place? (sorry if this is so basic). Your answer will probably relate to the conservation of energy. $\endgroup$
    – sidewaiise
    Commented Oct 9, 2014 at 4:05
  • $\begingroup$ @sidewaiise: if I've understood your question correctly it's something that has bothered me too. I've suggested my own question as a duplicate. $\endgroup$
    – John Rennie
    Commented Oct 9, 2014 at 10:20
  • $\begingroup$ Thanks @JohnRennie, its good to know someone else out there is notably stumped by this one. $\endgroup$
    – sidewaiise
    Commented Oct 10, 2014 at 4:11

1 Answer 1

Reset to default
1
$\begingroup$

All of our observations in particle physics have led to the so called standard model of physics. The particles in the table are characterized with several quantum numbers, spin, lepton number, baryon number, charge and a mass This states that all particles of matter are made out of a basic number of elementary particles,

standard model

with very specific rules governing the interaction and how they bind up into protons and neutrons that make up the bulk of matter as we know it.,

Protons are composed out of three quarks, and so are neutrons . The first left column is the one that characterizes bulk matter.

Electrons are elementary stable particles and so are photons and so appear in the table. The other particles in the basic table are produced by interactions that have been studied over the years .

Now lets take Hydrogen's antiparticle (anti-Hydrogen) and compare the structure - All the information I've found so far only points to a difference in charge without explaining the structure that governs the charge of the proton or anti-proton.

There exists a table for anti particles as the above one, whose only difference is that particles are changed to antiparticles. The first three columns from the left become antiparticle columns by setting the quantum numbers of baryon and lepton to their negative and multiplying the charge by -1.

The charge of the proton is built up by the charge of its quarks

proton

and the charge is reversed for antiprotons, and the quarks to antiquarks. The electron antiparticle is the positron, same mass opposite charge.

Improve this answer
$\endgroup$
7
  • $\begingroup$ I found this page: hyperphysics.phy-astr.gsu.edu/hbase/particles/quark.html which contains a table of Quarks and their respective charges/masses. Does this imply that an anti-proton may have a different combination of quarks in it, or a set of antiquarks which are of exactly opposite charge? $\endgroup$
    – sidewaiise
    Commented Oct 9, 2014 at 4:24
  • $\begingroup$ the latter: a set of antiquarks with opposite charge so that it adds up to -1e_c, the charge of the antiproton $\endgroup$
    – anna v
    Commented Oct 9, 2014 at 6:09
  • $\begingroup$ Thanks anna, your answer deserves a tick. It does however still stump me - the governing factors that determine a quark's state and existence. $\endgroup$
    – sidewaiise
    Commented Oct 10, 2014 at 4:12
  • $\begingroup$ If you continue your studies in physics, you must accept that "why's" are explained with "how" in the standard model one explains something. Ultimately we end at "because this is what we have observed and measured". Quarks are at the ultimate level of our measurements, they fit beautifully with the mathematical SM and thus we presume they exist. A quarks existence/creation depends on the available energy and the quantum numbers shown in the table, plus baryon and lepton number conservations. That is the how. Why quarks exist is metaphysical . New measurements might push the level further $\endgroup$
    – anna v
    Commented Oct 10, 2014 at 5:15
  • $\begingroup$ Anna, thanks. I guess I'm trying to envision a mechanical or quantum-mechanical process at tiny time intervals - the things that occur that we might have some control over some day that determine a quark's existence and state. $\endgroup$
    – sidewaiise
    Commented Oct 10, 2014 at 23:41

Not the answer you're looking for? Browse other questions tagged or ask your own question.