Vector Boson Fusion

126 Pages·2012·1.98 MB·English

Vector Boson Fusion:
Basics, Details & Examples
Barbara Ja¨ger
Institute for Theoretical Physics
University of Karlsruhe
Outline
8
the SM Higgs boson: a brief status report
8
vector boson fusion and its
importance for high energy physics
(cid:1)
interplay with related processes
(cid:1)
8
focus on V V production in VBF
theoretical concepts & techniques
(cid:1)
results
(cid:1)
8
summary & conclusions
III. Vector Boson Fusion / p. 1 Barbara Ja¤ger @ KEK, October 2006
Outline
8
the SM Higgs boson: a brief status report
8
vector boson fusion and its
importance for high energy physics
(cid:1)
interplay with related processes
(cid:1)
8
focus on V V production in VBF
theoretical concepts & techniques
(cid:1)
results
(cid:1)
8
summary & conclusions
III. Vector Boson Fusion / p. 1 Barbara Ja¤ger @ KEK, October 2006
The Unknown
Standard Model:
couplings and parameters
strongly constrained
only free parameter: M
H
(not yet measured)
still:
theory & experiment impose
variety of bounds on Higgs mass . . .
III. Vector Boson Fusion / p. 2 Barbara Ja¤ger @ KEK, October 2006
Theoretical Bounds on the Higgs Mass
triviality
M too large:
H
Higgs self coupling
Riesselmann,
blows up at some
hep-ph/9711456
scale (cid:3)
if SM is valid up to
vacuum stability (cid:3) Planck scale
(cid:25)
+
M too small: 130 . M . 180 GeV
H H
Higgs potential unstable
at large scale (cid:3)
III. Vector Boson Fusion / p. 3 Barbara Ja¤ger @ KEK, October 2006
Experimental Bounds on the Higgs Mass
direct search:
LEP: e+e ZH
(cid:0)
!
M & 114 GeV @ 95% CL
H
indirect search:
measure M , m , etc.
W t
constrain M
H
SM predictions vary LEP, SLC, CDF, D0:
2
M
ln H M . 260 GeV @ 95% CL
2 H
/ M
Z
[LEP EWWG 2005]
III. Vector Boson Fusion / p. 4 Barbara Ja¤ger @ KEK, October 2006
Experimental Bounds on the Higgs Mass
combined analysis of high-Q2
precision electroweak data
(assuming SM to be correct)
+73
M = 126 GeV
H 48
(cid:0)
III. Vector Boson Fusion / p. 5 Barbara Ja¤ger @ KEK, October 2006
To Do:
. . . need to learn more about the not yet discovered:
detect Higgs and determine M
H
(cid:15)
(or exclude its existence)
investigate properties of the Higgs carefully
(cid:15)
reveal: SM, SUSY, or something even different?
need to study couplings, charge,
spin, CP quantum numbers
but this . . .
III. Vector Boson Fusion / p. 6 Barbara Ja¤ger @ KEK, October 2006
To Do:
. . . requires:
identification of suitable search channels
(cid:1)
full understanding of most promising processes
(cid:1)
from experimentalists and theoreticians
III. Vector Boson Fusion / p. 7 Barbara Ja¤ger @ KEK, October 2006
Production Modes
reminder:
Higgs coupling
particle mass!
m
M /
f
W /
/
e
(cid:0) Z
direct Higgs production
Z
at e+e colliders
(cid:0)
mainly via Higgs strahlung
e+ H
III. Vector Boson Fusion / p. 8 Barbara Ja¤ger @ KEK, October 2006