Re:Particle seen switching between matter and antimatter at ...
by adrian_b on Saturday June 12, 2021 @02:00PM
(#27486258)
The title is confusing, because the whole particle does not switch between matter and antimatter, only its internal components switch.
The hadrons, i.e. the particles made of components bound together by the so-called strong nuclear forces are partitioned into 3 groups: particles made of 3 quarks, particles made of 3 anti-quarks and particles made of 1 quark together with 1 anti-quark.
Particles made from more quarks than in these 3 groups are possible in principle, but they would disintegrate extremely quickly, i.e. in times many orders of magnitude less than 1 nanosecond.
The reasons why only those 3 kinds of hadrons are normally encountered is that exactly like the electric forces attempt to neutralize the electric charge and prevent the negative charges to separate from the positive charges, the strong nuclear forces also try to neutralize a similar quantity, with the difference that this quantity is 2-dimensional, unlike the electric charge, which is 1-dimensional.
The condition of neutralizing that 2-dimensional quantity can be satisfied by the 3 kinds of quark combinations listed above.
The lightest hadron made of 3 quarks is the proton and the lightest hadron made of 3 anti-quarks is the anti-proton.
The proton and the similar hadrons can be considered as matter and the anti-proton and similar hadrons can be considered as anti-matter.
None of these hadrons made of either 3 quarks or 3 anti-quarks can switch between matter and anti-matter and this remains true for their compounds, like nuclei or anti-nuclei.
On the other hand, the 3rd kind of hadrons, which are usually named mesons, and which are made from 1 quark and 1 anti-quark, are in fact neither matter nor anti-matter.
The article linked here refers to a particle of this kind, where the total number of quarks is +1 -1 = 0.
So in mesons it is possible that the pair of 1 quark + 1 anti-quark will transform in another pair of 1 quark + 1 anti-quark, but where the quarks are different types of quarks than before the transformation. This transformation is possible because the total number of quarks is 0, both before and after the transformation, so any such transformation is possible as long as the new types of quarks are such so that the electrical charge remains the same.
The compositions of mesons can oscillate between different pairs quark + anti-quark, but the heavier mesons decay extremely fast so it is exceedingly difficult to observe such oscillations.
The linked article reports the experimental observation of such an oscillation, which was known as possible since decades ago, but it was not seen in experiments due to technical difficulties.
So in these transformations some quarks and anti-quarks appear and disappear, but the total quantity of matter and anti-matter is the same before and after, which is why the title is misleading.
The hadrons, i.e. the particles made of components bound together by the so-called strong nuclear forces are partitioned into 3 groups: particles made of 3 quarks, particles made of 3 anti-quarks and particles made of 1 quark together with 1 anti-quark.
Particles made from more quarks than in these 3 groups are possible in principle, but they would disintegrate extremely quickly, i.e. in times many orders of magnitude less than 1 nanosecond.
The reasons why only those 3 kinds of hadrons are normally encountered is that exactly like the electric forces attempt to neutralize the electric charge and prevent the negative charges to separate from the positive charges, the strong nuclear forces also try to neutralize a similar quantity, with the difference that this quantity is 2-dimensional, unlike the electric charge, which is 1-dimensional.
The condition of neutralizing that 2-dimensional quantity can be satisfied by the 3 kinds of quark combinations listed above.
The lightest hadron made of 3 quarks is the proton and the lightest hadron made of 3 anti-quarks is the anti-proton.
The proton and the similar hadrons can be considered as matter and the anti-proton and similar hadrons can be considered as anti-matter.
None of these hadrons made of either 3 quarks or 3 anti-quarks can switch between matter and anti-matter and this remains true for their compounds, like nuclei or anti-nuclei.
On the other hand, the 3rd kind of hadrons, which are usually named mesons, and which are made from 1 quark and 1 anti-quark, are in fact neither matter nor anti-matter.
The article linked here refers to a particle of this kind, where the total number of quarks is +1 -1 = 0.
So in mesons it is possible that the pair of 1 quark + 1 anti-quark will transform in another pair of 1 quark + 1 anti-quark, but where the quarks are different types of quarks than before the transformation. This transformation is possible because the total number of quarks is 0, both before and after the transformation, so any such transformation is possible as long as the new types of quarks are such so that the electrical charge remains the same.
The compositions of mesons can oscillate between different pairs quark + anti-quark, but the heavier mesons decay extremely fast so it is exceedingly difficult to observe such oscillations.
The linked article reports the experimental observation of such an oscillation, which was known as possible since decades ago, but it was not seen in experiments due to technical difficulties.
So in these transformations some quarks and anti-quarks appear and disappear, but the total quantity of matter and anti-matter is the same before and after, which is why the title is misleading.