Brain-teasers - Indico...Brain-teasers #1:Why is the top quark not in the Spin-the-Higgs wheel if it...
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Brain-teasers #1:Why is the top quark not in the Spin-the-Higgs wheel if it is the heaviest elementary particle? #2: What spin does the Higgs (actually) have? #3: Why is 125 GeV a ‘special’ mass for experimental physicists? [GeV] H M 80 100 120 140 160 180 200 Higgs BR + Total Uncert -4 10 -3 10 -2 10 -1 10 1 LHC HIGGS XS WG 2013 b b τ τ µ µ c c gg γ γ γ Z WW ZZ #3: Why is 125 GeV a ‘special’ mass for theorists? The Higgs is the only elementary particle with spin=0 found so far (elementary scalar) Only mass range where: - Decay to bb and is accessible - Decay rate to two photons is the highest among all possible Higgs masses and we want to study the Higgs coupling to all particles! A top-quark pair (173x2 GeV) is much larger than 125 GeV!!! The observed Higgs mass lies right at the edge between stability and instability regions. A small change in the Higgs mass (and top-quark mass) can drastically change our conclusions regarding the stability of the universe! for the Brave arXiv:1512.01222 [hep-ph]
Transcript of Brain-teasers - Indico...Brain-teasers #1:Why is the top quark not in the Spin-the-Higgs wheel if it...
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Brain-teasers#1:Why is the top quark not in the Spin-the-Higgs wheel if it is the
heaviest elementary particle?
#2: What spin does the Higgs (actually) have?
#3: Why is 125 GeV a ‘special’ mass for experimental physicists?
[GeV]HM80 100 120 140 160 180 200
Hig
gs B
R +
Tot
al U
ncer
t
-410
-310
-210
-110
1LH
C H
IGG
S XS
WG
201
3
bb
ττ
µµ
cc
gg
γγ γZ
WW
ZZ
#3: Why is 125 GeV a ‘special’ mass for theorists?
The Higgs is the only elementary particle with spin=0 found so far
(elementary scalar)
Only mass range where: - Decay to bb and 𝛕𝛕 is accessible
- Decay rate to two photons is the highest among all possible Higgs masses
and we want to study the Higgs coupling to all particles!
A top-quark pair (173x2 GeV) is much larger than
125 GeV!!!
The observed Higgs mass lies right at the edge between stability and
instability regions. A small change in the Higgs mass (and
top-quark mass) can drastically change our conclusions regarding the
stability of the universe!
for the Brave
arXi
v:15
12.0
1222
[hep
-ph]
-
Solution #1
Solution #2
#3: Why is 125 GeV a ‘special’ mass for experimental physicists?
[GeV]HM80 100 120 140 160 180 200
Hig
gs B
R +
Tot
al U
ncer
t
-410
-310
-210
-110
1LH
C H
IGG
S XS
WG
201
3
bb
ττ
µµ
cc
gg
γγ γZ
WW
ZZ
Solution #3
#3: Why is 125 GeV a ‘special’ mass for theorists?
Solution #4
#2: What spin does the Higgs (actually) have?
Brain-teasers for the Brave #1:Why is the top quark not in the Spin-the-Higgs wheel if it is the
heaviest elementary particle?
arXi
v:15
12.0
1222
[hep
-ph]
-
Spin is an intrinsic property carried by particles
Since the Higgs is a boson, its spin value is an integer number, but different from
that of the other elementary bosons
In how many ways can a 125 GeV Higgs boson decay?
We want to study the Higgs coupling to all particles!
In order to create a particle, enough energy is needed. Even more to create two! Energy and
mass are the same thing.
In which region lies the measured top quark mass (173 GeV) and Higgs
boson mass (125 GeV)?
What happens if the Higgs boson mass would have been lower or much
higher?
Need a hint?
