after the Higgs Discovery MV Chizhov Sofia University Bulgaria and JINR Russia 09062014 2 Why do we need the Higgs boson S ½ S 1 S 0 09062014 Harmonic Oscillator Analytical ID: 583150
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Slide1
Precision Measurementsafter the Higgs Discovery
M.V. ChizhovSofia University, Bulgaria and JINR, RussiaSlide2
09/06/20142
Why do we need the Higgs boson?
S = ½
S = 1
S = 0Slide3
09/06/2014Harmonic Oscillator
(Analytical Mechanics)
Joseph-Louis Lagrange
(
Giuseppe Lodovico
Lagrangia)
, 1788
3Slide4
R
> 0
R
< 0
09/06/2014
Harmonic
Oscillator
(Scalar
F
ield)
4Slide5
09/06/2014Scalar Potential of Anharmonic
Oscillator
5Slide6
09/06/2014Discrete Z2
Symmetry of
t
he Scalar Potential
6Slide7
Two Scalar Fields
(
or Complex
S
calar
F
ield
)
Potential with Broken
S
ymmetry
7Slide8
09/06/2014Continuous U(1) Symmetry of
the Potential with Complex Scalar Field
J. Goldstone, Nuovo Cim. 19 (1961) 154.
8Slide9
09/06/2014
Goldstone Particle (Theorem)
“if
there is continuous symmetry transformation under which the
Lagrangian
is
invariant
, then either the vacuum state is also invariant under the transformation,
or
there must exist
spinless
particles of zero mass
.”
Jeffrey Goldstone, Abdus
Salam and Steven Weinberg, Phys. Rev. 127 (1962) 965
9Slide10
09/06/2014
Examples of Collective Goldstone Bosons
Spin waves in a
ferromagnet
Phonons in a crystal lattice
Superfluidity
(Bose condensate
, Боголюбов,1947)
Superconductivity
(
Cooper pairs
, 1956
;
Боголюбов,1958)
Pions in the chiral limit (Nambu, 1961)
10Slide11
09/06/2014In Nature there is not a massless spinless
colorless particle, which would have had an infinite radius of interaction!
Only gravitational and electromagnetic forces have
an
infinite radius
of interaction.
Massless Particles in Nature
11Slide12
09/06/2014
Gauge Invariance
a
nd Massless Particles
A
m
12Slide13
09/06/201413
As Yang relates: Wolfgang
Pauli (1900-1958) was spending
the
year in Princeton, and was deeply
interested
in symmetries and interactions....
Soon
after my seminar began, when I
had
written
on the blackboard,
(∂m
-iBm
)
Pauli asked, "
What is the mass of this field
B
m
?
" I said we did not know. Then I resumed my presentation but soon
Pauli asked the same question again
.
I said something to the effect that it was a very complicated problem, we had worked on it and had come to no definite conclusions. I still remember his repartee: "That is not sufficient excuse".
An Anecdote by C. N. Yang Slide14
09/06/2014S. L. Glashow, Nucl. Phys. 22 (1961) 579.
Birth of the Standard Model of
Elementary Particles
SU(2)
L
U(1)
Y
“Schwinger told me to think about unifying weak and EM.
So I did it. For two years ‒ I thought about it.”
14Slide15
09/06/201415
Unitarity
and Z bosonSlide16
09/06/201416
Unitarity
and Higgs boson
Not yet tested experimentally… but see the following slide! Slide17
09/06/201417Evidence of electroweak W
±W±jj
production
ATLAS-CONF-2014-013 (March 25,
2014),
arXiv:1405.6241
Inclusive
m
jj
QCD+EW region
Enriched VBS region:
m
jj
>500
GeV
, |
D
y
jj
|>2.4Slide18
09/06/2014
Gauge Invariance
a
nd Massive
P
articles
Schwinger
model
(1962):
two-
dimentional
quantum electrodynamics
, where the photon becomes massive.
Non-relativistic dynamics of the plasma:
Philip
W.
Anderson
(
1963) –
Yang
Mills fields acquire the mass
due to longitudinal oscillations in plasma
(
Meissner
Ochsenfeld
effect
)
.
A
m
2
“We conclude
, then, that the Goldstone zero-mass
d
ifficulty is
not a serious one, because we can
probably
cancel
it off
against an equal Yang-Mills
zero-mass problem.”
18Slide19
F. Englert and R. Brout, Phys. Rev.
Lett. 13 (1964) 321 (June 26
, 1964)
P. W. Higgs, Phys. Rev.
Lett
. 13 (1964)
508
(
August
31, 1964)
G. S. Guralnik,
C. R. Hagen, and T.
W.
B.
Kibble
,
Phys
. Rev.
Lett
. 13 (1964)
585
(
Octomber
12, 1964)
Englert
-
Brout
-Higgs-
Guralnik
-Hagen-Kibble mechanism on one page
19Slide20
09/06/2014
Goldstone
and
Higgs
Particles
Jeffrey
Goldstone
Peter
W. Higgs
Phys.
Rev
. 145 (1966) 1156
H → Z Z
“it
is worth noting that an
essential feature of
this type
of
theory is the
prediction of
incomplete
multiplets
of
scalar
and vector bosons
.”
Phys.
Rev
.
Lett
. 13 (1964) 508
20Slide21
09/06/2014Neither Salam and Ward, who worked at Imperial College in the same group with Guralnik, Hagen and Kibble, nor Glashow, who after Higgs seminar at Harvard on March 16, 1966 said: "that is a nice model, Peter" have
realized that they could use this mechanism for generation of masses.
Omitted Opportunities
Glashow (1961)
Salam & Ward
(1964)
Salam & Ward
(
Sept
24
,
1964→
Nov 15,
1964)(On
Monday, October 5
, Peter
Higgs gave a seminar about his mechanism at Imperial
College
?
)
GHK
(Oct
12
,
1964 →
Nov
16
,
1964
)
“All
of us,
Brout
,
Englert
and myself, had been going in the
wrong direction, looking at hadron symmetries
.
”
P.W. Higgs
21Slide22
SU(2)
L
U(1)
Y
Using of EBHGHK mechanism
S. Weinberg
(1967)
& A. Salam (196
8
)
→ Nobel Prize
1979
relation
between the masses of
intermediate
bosons
M
W
=
M
Z
cos
W
through
the
mechanism
of
spontaneous symmetry
breaking
09/06/2014
22Slide23
Lagrangian
of
t
he Standard Model
09/06/2014
23Slide24
09/06/2014
Mathematical Foundation oft
he Standard Model
(
theory
)
G
. ’t
Hooft
&
M. J. G.
Veltman
(1972)
→ Nobel Prize
19
9
9
renormalizability
of non-abelian gauge theories with broken symmetry is proven
a drawing of their most important discovery
24Slide25
Discovery of the weak neutral interactions mediated by Z boson
in experiment with bubble chamber Gargamelle at CERN (1973)
Establishment of
t
he Standard Model
(
experiment
)
sin
2
W
~ 0.3
-
0.5
M
W
=50
-
70
GeV
M
Z
=75
-
80
GeV
09/06/2014
25Slide26
09/06/2014
Hunt for the Higgs Boson
26
John F.
Gunion
,
Howard E.
Haber,
Gordon
L.
Kane, Sally Dawson,
The
Higgs Hunter's
Guide,
Upton,
NY:
Brookhaven
Nat. Lab., 1989. - 404 p.Slide27
09/06/2014began work on November 30, 1986 and
stopped on September 30, 2011
TeVatron
at FNAL
27Slide28
09/06/201428
Tevatron Higgs ExclusionSlide29
09/06/2014
Large
Electron
‒
Positron
(
LEP) collider
at CERN
started in August 1989 and ended in late 2000
DELPHI
L3
ALEPH
OPAL
29Slide30
09/06/201430
Direct LEP exclusionSlide31
09/06/201431
Indirect constraints on Higgs massSlide32
Large Hadron Collider (LHC)
09/06/2014
32
10
9
interactions
per second
1.5
10
11
p
2
1380 bunchesSlide33
09/06/2014
July 4, 201233Slide34
09/06/201434Is it the Higgs, or isn’t Higgs?