About The Mysterious World of Fundamental Particles |
|
If you bought this ebook (or
paperback edition) and read it completely, you would find,
whatever has been given in the sample has been explained in
detail in the rest of the book so that when you reached the end
of the book, you would really feel enlightened.
1. Neutral Bottom Xi-star Baryon The neutral bottom Xi-star baryon Ξ*b0
(usb) was
discovered in 2012, in the Large Hadron Collider LHC,
which accelerated proton-proton pairs to cms energy of 7000 GeV
(i.e. each proton having energy of 3500 GeV).
The neutral bottom Xi-star baryon Ξ*b0
(usb) decayed rapidly in a cascade of decays to lower mass
particles The neutral bottom Xi-star baryon Ξ*b0
(usb) decayed instantaneously into a negative bottom Xi
baryon Ξb−
(dsb) and a positive pion:
Ξ*b0 (usb) → Ξb−
(dsb) + π+ (ud`) (mass of Ξ*b0
(usb) = 5949.4 MeV,
mass of Ξb−
(dsb) = 5794.9 MeV,
mass of π+ (ud`) = 139.57 MeV) When the three quarks - up, strange and
bottom get together to produce a neutral bottom Xi-star baryon,
they immediately separate because the bottom quark is very
massive. The up quark
moves away from the strange and the bottom quark and
emits a gluon and the
up quark remains itself as an
up quark u. The gluon
then decays into a down
quark d and an
antidown quark d`. This
antidown quark d`
combines with the up
quark u (which had emitted the gluon) of the neutral bottom
Xi-star baryon to produce a positive pion
π+ (ud`).
The down quark d
(produced by the decay of the gluon) combines with the strange
quark and the bottom quark of the neutral bottom Xi-star baryon
to produce a negative bottom Xi baryon Ξb−
(dsb) The negative bottom Xi baryon Ξb− (dsb) was the first known particle made of quarks from all three quark generations.
2. Positive Bottom Sigma-star Baryon The positive bottom sigma-star baryon Σ*b+
(uub) was discovered through its rapid decay into a
neutral bottom lambda baryon Λb0 (udb) and
a positive pion π+ (ud`):
Σ*b+ (uub) → Λb0
(udb) + π+ (ud`) (mass of
Σ*b+
(uub) = 5832.1 MeV,
mass of Λb0 (udb) = 5619.5 MeV,
mass of π+ (ud`) = 139.57 MeV)
Here, one
up quark of the
positive bottom sigma-star baryon
emits a gluon and the
up quark remains itself as an
up quark u. The
gluon then decays into a down quark d and an antidown quark d`. This
antidown quark
d` combines with the
up quark
u (which had emitted the gluon) of the positive bottom sigma-star baryon
to produce a
positive pion π+ (ud`). The down quark d (produced by the decay of the gluon) combines with the remaining up quark and the bottom quark of the positive bottom sigma-star baryon to produce a neutral bottom lambda baryon Λb0 (udb).
3. Omega Baryon The omega baryons consist of three
quarks but contain no up or down quarks. They may have +2, +1,
−1 or 0 unit of electric charge. The first omega baryon was discovered in
1964 in bubble chamber. It was the negative omega baryon Ω−,
whose constituents were three strange quarks. The omega baryon was first discovered in
bubble chamber in 1964. In those first omega events, incoming negative Kaon K− (u`s)
collided with a proton p (uud) in bubble chamber and decayed
into an omega baryon Ω− (sss), a positive kaon K+
(us`) and a neutral Kaon K0 (ds`).
K−
(u`s) + p (uud)
→
Ω− (sss) + K+ (us`) + K0 (ds`)
This is a strong interaction as strangeness is conserved.
Strangeness is S = -1 before the interaction and S = -3 + 1+ 1 =
- 1 after the interaction. In this case,
one up quark of the
proton and the antiup quark of the negative Kaon annihilate to a
gluon, which then materializes into a
strange quark s and
an antistrange quark s`.
Another up quark of the proton
emits a gluon and
remains itself as an up quark. The gluon subsequently decays
into a strange quark s
and an anti-strange quark s`. Thus, the two gluons involved
in this interaction produce two strange quarks and two
antistrange quarks. These
two strange quarks combine with the strange quark of the
negative Kaon to produce an omega baryon Ω− (sss).
One antistrange quark s` combines with the surviving up quark u
(which had emitted the gluon) of the proton to produce a
positive Kaon K+ (us`). Another antistrange quark s`
combines with the down quark d of the proton to produce a
neutral Kaon K0 (ds`). decay modes of Ω− (sss): Λ0 (uds) + K− (u`s) (BR: 67.8%); Ξ0 (uss) + π− (u`d) (BR: 23.6%); Ξ− (dss) + π0 (uu`) (BR: 8.6 %)
Explanations of these decay modes have been given in the book: The Mysterious World of Fundamental Particles.
|