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About The Mysterious World of Fundamental Particles |
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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.
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Favourite Particles of Mohit Joshi |
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1. Positive Bottom Sigma-star Baryon Sigma means one strange quark and two up/down quarks. Bottom Sigma means one strange quark replaced by one bottom quark. So Bottom Sigma has no strange quark but one bottom quark. Charge of bottom quark is -1/3e. So Positive Bottom Sigma must have 2 up quarks (charge of up quark: +2/3e) as second and third quarks to make total charge +1e. So Positive Bottom Sigma-star Baryon means uub. |
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The
positive bottom sigma-star baryon Σ*b+
(uub) decayed rapidly
to lower mass particles: Σ*b+ (uub) → Λb0 (udb) + π+ (ud`) Λb0 (udb) → Λc+ (udc) + π− (u`d) Λc+ (udc) → p (uud) + K− (u`s) + π+ (ud`)
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)
Λb0
(udb) and π+ (ud`) appeared straight at the point,
where the positive bottom sigma-star baryon Σ*b+
(uub) produced because the positive bottom sigma-star
baryon Σ*b+ (uub) will travel almost zero
distance in a lifetime τ
= 5.7 × 10−23 s.
In this case, bottomness is conserved. Thus, this is a strong
decay i.e. through gluon. 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 that
up quark
u of
the positive bottom sigma baryon which
had emitted the gluon and produces 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). |
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The neutral bottom lambda baryon Λb0
(udb) decayed into a positive charmed lambda baryon Λc+
(udc) and a negative pion π− (u`d) after travelling
some distance in its lifetime τ = 1.45 × 10−12 s: Λb0 (udb) → Λc+ (udc) + π− (u`d)
In this decay, bottomness and charmness are not conserved. Thus,
this is a weak decay i.e. through W boson.
In this case, the
bottom quark b
(charge: -1/3e) of the neutral bottom lambda baryon emits a W−
boson and transforms into
a charm quark
c (charge: +2/3e) and the neutral bottom lambda baryon transforms into a
positive charmed lambda baryon Λc+
(udc).
The W− boson then decays
into an antiup
quark u` (charge:
-2/3e) and a down quark d
(charge: -1/3e), which combine to produce a
negative pion π− (u`d).
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The positive charmed lambda baryon Λc+
(udc) decayed into a proton p (uud), a negative kaon K−
(u`s) and a positive pion π+ (ud`) after travelling
some distance in its lifetime τ = 2 × 10−13 s: Λc+ (udc) → p (uud) + K− (u`s) + π+ (ud`)
In this decay, charmness and strangeness are not conserved.
Thus, this is a weak decay.
In this case, the
charm quark c
(charge: +2/3e) of the positive charmed lambda baryon emits a W+
boson and transforms into
a strange quark
s (charge: -1/3e).
The W+ boson then decays
into an up quark u
(charge: +2/3e) and an
antidown quark d` (charge: +1/3e), which combine to produce
a
positive pion π+ (ud`).
The up quark of the positive
charmed lambda baryon
emits a gluon and the
up quark remains itself as an
up quark u.
The
gluon then decays into an up quark u and an
antiup quark u`. This antiup
quark u` combines
with the strange quark s
(produced by the transformation of the charm quark) to
produce a negative Kaon K− (u`s).
The up quark u (produced by the decay of the gluon) combines with the
down quark d of the
positive charmed lambda
baryon and that up
quark u of the positive charmed lambda
baryon which had emitted the gluon and produces a
proton p (uud).
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2. Neutral Bottom Xi-star Baryon
Xi means 2 strange quarks and one up/down quark. Bottom Xi means one
strange quark replaced by one bottom quark. So Bottom Xi has one s
and one b. Sum of the charge of one s and one b is -2/3e. So neutral
Bottom Xi-star must have u (charge +2/3e) as the third quark to make
total charge 0e. So
Neutral Bottom Xi-star Baryon means usb. |
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The neutral bottom Xi-star baryon Ξ*b0 (usb) decayed rapidly in a cascade of decays to lower mass particles: Ξ*b0 (usb) → Ξb− (dsb) + π+ (ud`)
Ξb−
(dsb) → J/ψ (cc`) + Ξ−
(dss)
(b to s) J/ψ (cc`) → μ+ + μ− Ξ− (dss) → Λ0 (uds) + π− (u`d) Λ0 (uds) → p (uud) + π− (u`d)
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) was discovered
through its rapid decay 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)
Ξb−
(dsb) and π+ (ud`) appeared straight at the point,
where the neutral bottom Xi-star baryon Ξ*b0
(usb) produced because Ξ*b0 (usb)
will travel almost zero distance in its lifetime τ = 3.13 × 10−22
s.
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 that up
quark u
of the neutral bottom Xi-star
baryon which had emitted the gluon and produces 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. The down, strange and bottom quarks are the first, second and third generation quarks respectively.
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The negative bottom Xi baryon Ξb−
(dsb) decayed into a J/ψ meson (cc`) and a negative Xi
baryon Ξ− (dss) after travelling some distance in its
lifetime τ = 1.56 × 10−12 s:
Ξb−
(dsb) → J/ψ (cc`) + Ξ−
(dss)
In this decay, strangeness and bottomness are not conserved.
Thus, it is a weak decay.
In this case, the
bottom quark b
(charge: -1/3e) of the negative bottom Xi baryon
emits a W−
boson and
transforms into a charm quark
c (charge: +2/3e).
The W− boson then decays
into a strange quark s
(charge: -1/3e) and an
anticharm quark c` (charge: -2/3e). This
anticharm quark c`
combines with the charm
quark
c (produced by the
transformation of the bottom quark) to produce a
J/ψ meson (cc`)
The
strange quark s
(produced by the decay of the W−
boson) combines with the down quark and the strange quark
of the negative bottom Xi baryon to produce a
negative Xi baryon Ξ− (dss).
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The J/ψ meson (cc`)
produced by the decay of the negative bottom Xi baryon
Ξb−
(dsb) decayed into a
muon-antimuon pair
μ+μ−.
The pair appeared straight at the point, where the negative
bottom Xi baryon Ξb− (dsb) decayed into
J/ψ meson and Ξ− (dss) because J/ψ meson will travel
almost zero distance in a lifetime τ = 7.1 × 10−21 s. J/ψ (cc`) → μ+ + μ−
The
charm quark c
(charge: +1/3e) and anti charm quark c` (charge: -1/3e) annihilate
to
virtual photon when then decay into muon anti muon pair. |
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The negative Xi baryon Ξ−
(dss)
produced by the decay of the negative bottom Xi baryon
Ξb−
(dsb) decayed into a
lambda baryon Λ0 (uds) and a negative pion π−
(u`d) after travelling some distance in its lifetime τ =
1.639 × 10−10 s: Ξ− (dss) → Λ0 (uds) + π− (u`d)
In this decay, strangeness is not conserved. Strangeness is S =
-2 and -1 before and after the decay respectively, thus this
decay is through the weak process.
In this case, one
strange quark
(charge: -1/3e) of the negative Xi baryon
emits a W−
boson and transforms into
an up quark u
(charge: +2/3e) and
the negative Xi baryon transforms into a
lambda baryon Λ0 (uds).
The W− boson (charge: -1e)
then decays into an
antiup
quark u` (charge:
-2/3e) and a down quark d
(charge: -1/3e), which combine to produce a
negative pion π− (u`d). |
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The lambda baryon Λ0 (uds)
produced by the decay of the negative Xi baryon
Ξ−
(dss)
decayed into a proton p (uud) and a negative pion π−
(u`d) after travelling some distance in its lifetime of τ = 2.632 × 10−10
s: Λ0 (uds) → p (uud) + π− (u`d)
In this decay, strangeness is not conserved. Strangeness is S =
-1 and 0 before and after the decay respectively, thus this
decay is through the weak process that is, through a W boson.
In this case, the
strange quark
(charge: -1/3e) of the lambda baryon
emits a W−
boson and
transforms into an up quark u
(charge: +2/3e) and
the lambda baryon
transforms into a
proton p (uud).
The
W− boson subsequently decays into an antiup quark u`
(charge: -2/3e) and a down quark d (charge: -1/3e).
The antiup quark and the down quark combine to produce a
negative pion π− (u`d). |
| 3. Omega Baryon |
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The omega baryon was 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 produced 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 that up quark u of the proton which had emitted the gluon and produces 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`).
The omega baryon Ω− (sss) decayed rapidly in a cascade of decays to lower mass particles: Ω− (sss) → Ξ0 (uss) + π− (u`d) (s to u)Ξ 0 (uss) → Λ0 (uds) + π0 (uu`)Λ 0 (uds) → p (uud) + π− (u`d)
π−
(u`d)
→ μ− +
νμ`
μ−
→ e− + νe`
+ νμ
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The omega baryon Ω− (sss)
decayed into a neutral Xi baryon Ξ0 (uss)
and a negative pion π− (u`d)
after travelling some distance in its lifetime τ = 8.21 × 10−11
s: Ω − (sss) → Ξ0 (uss) + π− (u`d)
In this decay, strangeness is not conserved. Strangeness is S =
-3 and -2 before and after the decay respectively, thus this
decay is through the weak process.
In this case, one of the
strange quarks (charge: -1/3e) of the omega baryon
emits a W−
boson and
transforms into an up quark u
(charge: +2/3e) and the omega baryon transforms into a
neutral Xi baryon Ξ0
(uss).
The W− boson (charge: -1e) then decays into an
antiup quark u` (charge: -2/3e) and a
down quark d (charge: - 1/3e) thereby producing a
negative pion π−
(u`d).
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The neutral Xi baryon Ξ0 (uss) then decayed into a lambda baryon Λ0 (uds) and a neutral pion π0 (uu`) after travelling some distance in its lifetime τ = 2.9 × 10−10 s:
Ξ0
(uss)
→ Λ0 (uds) + π0
(uu`)
In this decay too, strangeness is not conserved. Strangeness is
S = -2 and -1 before and after the decay respectively, thus this
decay is through the weak process.
In this case, one strange
quark (charge: -1/3e) of the neutral Xi baryon
emits a W−
boson and
transforms into an up quark
u (charge: +2/3e).
The W− boson (charge: -1e) then decays into an
antiup quark
u` (charge: -2/3e)
and a down quark
d (charge: - 1/3e). This
antiup quark u` combines with the
up quark
u (produced by the
transformation of the strange quark) to produce a
neutral pion π0
(uu`). The down quark d (produced by the decay of the W− boson) combines with the up quark and the surviving strange quark of the Xi baryon to produce a lambda baryon Λ0 (uds). |
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The neutral pion π0
(uu`)
produced by the decay of the neutral Xi baryon
Ξ0 (uss)
decayed into photon-pair.
The photon-pair appeared straight at
the point, where the neutral Xi baryon decayed into Λ0
(uds) and π0 (uu`)
because neutral pion will travel almost zero distance in
a lifetime τ = 8.5 × 10−17 s, even if its velocity is
nearly equal to that of light.
Each photon then decayed into e+e− pair in
traversing the liquid hydrogen.
(Electromagnetic decay)
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The lambda baryon Λ0 (uds)
produced by the decay of the neutral Xi baryon
Ξ0 (uss)
decayed into a proton p (uud) and a negative
pion π− (u`d)
after travelling some distance in
its lifetime τ = 2.632 × 10−10 s:
Λ0
(uds)
→
p (uud) + π− (u`d)
The negative pion π− (u`d) decays into a muon μ− and a muon-type antineutrino νμ`after travelling some distance in its life time τ = 2.6 ×10−8 s:
π−
(u`d)
→ μ− +
νμ` In this case, the antiup quark u` (charge: -2/3e) and the down quark d (charge: -1/3e) of the negative pion annihilate to a W− boson (charge: -1e), which then decays into a muon μ− and a muon-type antineutrino νμ` |
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The muon μ- decays
into an electron e−, an electron-type antineutrino νe`
and a muon-type neutrino νμ after
travelling some distance in its life time τ = 2.2 ×10−6
s:
μ−
→ e− + νe`
+ νμ
In this case, the muon μ− with one unit of negative
electric charge emits that one unit of negative electric charge
by emitting a W− boson and therefore transforms into
the corresponding electrically neutral lepton that is,
muon-type neutrino νμ.
The W− boson subsequently decays into an
electron e−
and the corresponding antineutrino, i.e.
electron-type antineutrino νe`. 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 %) |