文档介绍：Higgs Physics
Yasuhiro okada(Kek
November 26. 2004. at KEK
Higgs mechanism
One of two principles of the Standard Model
“ Gauge invariance”and" Higgs mechanism
Origin of the weak scale
Why is the weak interaction so weak?
F
√2u
2
Goals of Higgs physics
nd Higgs bosons and establish the mass
generation mechanism of quarks, leptons and
the gauge bosons
Coupling constant measurements
Clarify physics behind the electroweak symmetry
breaKing
What is the Higgs particle?
Elementary or composite?
A window to the physics beyond the Standard
Mode
Higgs boson mass
lggs mass-> Strength of the dynamics
responsible for the electroweak symmetry
breaking
n the sm
m
√2入U
121}2+(4
n general
a light Higgs boson is consistent with
weakly interacting scenario
(GUT/SUSY/String unification )
a heavy Higgs boson implies
strongly interacting scenario
Theoretical bounds on the higgs boson
mass in the sm
RGE for the Higgs self-coupling constant in the SM
Adma
(24入2+12v入-6v2+…)
mt=170 GeV
f we require that the sm is valid
mh=6oo Gev
to 1019 GeV
130GeV< mh 180 GeV
mh=300 Gev
mhs 180 Gev
mh=150 Gev
mh=80Gev
Energy scale(Gev)
Higgs mass in SUSY models
SUsY models include at least two Higgs doublets
n the minimal SUsY Standard model (MSSM), the
ightest CP-even Higgs boson mass has theoreti
upper bound
VHg,=m1H12+m2H2-m2(H1·H2+H1H2)
y(H1r"H1+H2H12+y(H12-12)2
△V
na co
mh< 135GeV
Possible vacuum instability is saved by supersymmetry
Possible range of the lightest Higgs boson
mass for the planck scale cutoff
Higgs Boson Mass Range
(The cutoff scale Planck scale
100
150
200
250(GeV)
Standard model
Two Higgs Doublet Model
MSSM
NMSSM
→ General sUSy Model
As long as theory behaves weakly-coupled up to the Planck scale
the higgs bosom mass is les than 200 geV.
Precision EW test and the higgs mass
In the SM, the global fit suggests a light Higgs boson
M. Peskin and J. Wells
world-average Mroc
. All da