symmetry and its violation -unifying concept of universe- tatsuya nakada lausanne, 8 february 2000
TRANSCRIPT
Symmetry and Its Violation-unifying concept of universe-
Tatsuya Nakada
Lausanne, 8 February 2000
Nature
Concept of Symmetry
- regular pattern- symmetry- …
RecognitionNature Observation
Creating arts
- regular pattern- symmetry- …
Concept Realisation
Natural Science
Observation Generalising andmaking physical laws
Extracting moreabstract concept
Postulatingand
predictingphenomena
Observation
f = Gm1 m2
r2
gg
Other examples of symmetry
and Islam
ic beau
ties
Too symmetric is “unnatural”.
Some asymmetry makes… more dynamic
more beautiful
if not too much…?
Geometrical Symmetries
Translation Rotation Reflection(parity)
RRRRRRRRRR
RR RRRR
RRR
RR
R
continuous continuous discrete
Spontaneous Breakdown of Rotational Symmetry
before dinner once dinner starts
Violation of L-R Symmetry
World
10%90%
Mirror World
90%10%
World Mirror World(parity violation)
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
Atomic System
Building Force Underlyingblocks dynamics
electron and electromagnetic Quantumnucleus interaction Mechanics
(relativistic)
Solar System
Building Force Underlyingblocks dynamics
sun and planets gravitation Newton’s lawsof motion
Elementary Particle System
Building Force Underlyingblocks dynamics
quarks and electromagnetic Quantumleptons (photon: ) Field
+ weak Theoryanti-quarks and (W, Z0)
anti-leptons strong(gluon: g)
The Standard Model
q
q
e
e
W
q
q
e
g
q
q
q
q
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)
orsome “internal” space
What about discrete symmetries?
Parity: (x, y, z) (x, y, z)we saw already
Charge conjugation: particle antiparticleTime reversal: t t
two more to come
No quantum field theory without CPT symmetry
particle world antiparticle world
antineutrinoneutrino
Right-handedLeft-handed
connected byCP
transformation
CP Violation
We know two examples which showsmatter world anti-matter world.
CP symmetry is violated !!
Evolution of Universe
big bang
matter
anti-matter
amount of matter = amount of anti-matter
our universeonly with matter
CP violation
Weak decay of neutral K mesons
K Decay Time
CPLEAR Experiment (1999)
neutral kaondecay time distribution
anti-neutral kaondecay time distribution
CP violation
Problem!!
CP violation inthe kaon decays
canbe explained by
the Standard Model.
CP violation inthe 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
W
q
q
complex coupling constant
Standard Model
X
q
q
complex coupling constant
New Physics
CP transformation containscomplex conjugation:
eiH t eiH*t
i.e. H* H CP violation
At LHC
p7 TeV= cal
1g of those p’s = 20 daysof US energy consumption
p7 TeV
LHCb detector
14 TeV mini bang
~100 times more B mesons then before
CERN and LHC
CERN
Users
LHCbYoke
RICH-1
Vertex
Shieldingplate
TrackerCalorimeters
MounRICH-2
Coil
The LHCb Experiment
Netherlands
Brazil
France
Germany
Italy PRC Romania Spain
Switzerland
Ukraine
UK
USA
Poland Russia
Finland
An EventLHCb eventseen by the vertex detector(Lausanne participation)
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/teach particle physics?
- applied research will achieve “state of art”.- basic research opens new horizon.
Why do we do basic research?
- understanding the most fundamental nature of material isone of the most important cultural activities.
- elementary particles are one of the basic concepts of modern physics which should be known by everybody.
No Maxwell, no radio nor TV.No Röntgen, no X ray picture.No Quantum Mechanics, no modern electronics
Everybody knows that the earth is round!
- experiments demands state of art technology: spin-off.
- students learn how to work in an internationalcollaboration with a given time scale andstill to remain creative.
Why do we do experimental particle physics?
We are all curious to knowhow we are here!