Download Symmetry and Its Violation -unifying concept of universe

Lausanne, 8 February 2000
Symmetry and Its Violation
-unifying concept of universe-
Tatsuya Nakada
Nature
Concept of Symmetry
- regular pattern
- symmetry
-…
Nature
Observation
Recognition
Creating arts
- regular pattern
- symmetry
-…
Concept
Realisation
Natural Science
m1 m2
f= G 2
r
Generalising and
making physical laws
Observation
gmn g
Extracting more
abstract concept
mn
Postulating
and
predicting
phenomena
Observation
Too symmetric is “unnatural”.
Some asymmetry makes… more
dynamic
more beautiful
if not too much…?
Geometrical Symmetries
Translation
Reflection
(parity)
Rotation
R
continuous
R
R
RR
RR
RR
RR
RR
continuous
discrete
Spontaneous Breakdown of Rotational
Symmetry
before dinner
once dinner starts
Violation of L-R Symmetry
World
90%
Mirror World
10%
10%
World  Mirror World
(parity violation)
90%
Even more with DNA
L-R symmetry is fully violated.
World
Goal of Elementary Particle Physics
To look for
1) the ultimate building blocks of the world
2) forces between them
3) underlying dynamics
Examples
Building
blocks
sun and planets
Building
blocks
electron and
nucleus
Solar System
Force
Underlying
dynamics
gravitation Newton’s laws
of motion
Atomic System
Force
Underlying
dynamics
electromagnetic Quantum
interaction
Mechanics
(relativistic)
Elementary Particle System
qq
qn
Building
Force
Underlying
e
blocks
dynamics
quarks and electromagnetic Quantum
leptons
(photon: g)
Field
+
weak
Theory
gg
W
anti-quarks and
(W, Z0)
anti-leptons
strong
(gluon: g)
The Standard Model
q
qe
Properties of
building blocks, forces and underlying dynamics
can be described by
rotation and/or translation symmetries
in
four-dimensional real space (t, x, y, z)
or
some “internal” space
What about discrete symmetries?
we saw already
Parity:
(x, y, z)  (-x, -y, -z)
two more to come
Charge conjugation: particle  antiparticle
Time reversal:
t  -t
No quantum field theory without CPT symmetry
particle world
neutrino
antiparticle world
antineutrino
connected by
CP
transformation
Left-handed
Right-handed
CP Violation
We know two examples which shows
matter world  anti-matter world.
CP symmetry is violated !!
Evolution of Universe
matter
big bang
anti-matter
amount of matter
= amount of anti-matter
our universe
only with matter
CP violation
Weak decay of neutral K mesons
Decay Time
0
+ -
K  pp
CPLEAR Experiment (1999)
neutral kaon
decay time distribution

anti-neutral kaon
decay time distribution
CP violation
Problem!!
CP violation in
the kaon decays
can
be explained by
the Standard Model.

CP violation in
the universe
cannot
be explained by
the Standard Model.
LHCb experiment will look for CP violation
beyond the Standard Model in the particle world
using B-mesons.
Mechanism of CP Violation
Standard Model
New Physics
q
q
W
CP transformation contains
X
complex conjugation:
-iH t
iH*t
complex coupling constant e complex
 coupling
e
constant
i.e. H*  H CP violation
q
q
At LHC
p
7 TeV=2.710-7 cal
1g of those p’s = 20 days
of US energy consumption
14 TeV
~100 times more
B mesons then before
p
7 TeV
mini bang
LHCb detector
CERN and LHC
CERN
Users
The LHCb Experiment
Brazil
Shielding Yoke
Coil
plate
Calorimeters
Tracker
USA
LHCb
Finland
Ukraine
UK
France RICH-1
RICH-2
Germany
Moun Switzerland
Vertex
Italy
Netherlands
PRC
Poland
Romania
Russia
Spain
LHCb event
An
seen by the vertex detector
(Lausanne participation)
Event
Primary Goal of LHCb
To understand better
the origin of CP violation.
Possibly discovering
new physics beyond the Standard Model.
FAQ
Why do we do basic research?
- applied research will achieve “state of art”.
- basic research opens new horizon.
No Maxwell, no radio nor TV.
No Röntgen, no X ray picture.
No Quantum Mechanics, no modern electronics
Why do we do/teach particle physics?
- understanding the most fundamental nature of material is
one of the most important cultural activities.
- elementary particles are one of the basic concepts of
modern physics which should be known by everybody.
Everybody knows that the earth is round!
Why do we do experimental particle physics?
- experiments demands state of art technology:
 spin-off.
- students learn how to work in an international
collaboration with a given time scale and
still to remain creative.
We are all curious to know
how we are here!