Symmetry Transformation or Operations in Particle Physics

Symmetry Transformation or Operations in Particle Physics

1. PRESENTED BY: DEVANSHI AND SAKSHI 1 SYMMETRIES IN PARTICLE PHYSICS

2. Symmetry ,in physics the concept that the properties of particles such as atoms and molecules remain unchanged after being subjected to a variety of symmetry transformation or “operations”. The application of symmetry to physics leads to the important conclusion that certain certain physical laws particularly conservation laws, governing the behaviour of objects and particles are not affected when their geometric Coordinates are transformed by means of symmetry operations. Valid symmetry operations are those that can be performed without changing the appearance of an object . Elementary particles are also said to have internal symmetry; these symmetries are useful in classifying particles. There is a fairly strong proof that only minimal physical assumptions that the product of C,P and T is a good symmetry of any theory. 2 SYMMETRY

3. TYPES OF SYMMETRIES SYMMETRIES Discrete symmetry Continuous symmetry 3

4. A discrete symmetry is a symmetry that describes non Continuous Changes in a system . For example, a square possesses discrete Rotational symmetry as only rotations by multiplies of right Angles will preserve the square’s original appearance. Discrete Symmetries sometimes involve some type of swapping these Swaps usually being called reflections or interchanges . One of the Most prominent discrete symmetries in physics is parity symmetry. DISCRETE SYMMETRY ; 4

5. CONTINUOUS SYMMETRY In physics continuous symmetry is an intuitive idea corresponding to the concept of viewing some symmetries as motion, as opposed to discrete symmetry ,e.g. reflection symmetry, which is invariant under a kind of flip from one state to another. However ,a discrete symmetry can always be reinterpreted as a subset of some higher-dimensional continuous symmetry, e.g. reflection of 2-D object in 3-D space. 5

6. TERMS IN DISCRETE SYMMETRY 1 . CHARGE CONJUGATION In physics , charge conjugation is a transformation that switches all particles with their corresponding antiparticles, thus changing the sign of all charges; not only electric charge but also the charges relevant to other forces . The term C- symmetry is an abbreviation of the phrase charge conjugation symmetry and is used in the discussions of the symmetry of physical laws. 6

7. 2 . PARITY In physics ,parity transformation is the flip in the sign of one Spatial coordinate. In three dimensions , it can also refer to the simultaneous flip in the sign of all three spatial coordinates. P : x -x y ↔ -y z -z It can also be thought of as a test for chirality of a physical Phenomenon. 7

8. 3. TIME REVERSAL SYMMETRY Time reversal symmetry is the theoretical symmetry of physical Laws under the transformation of time reversal, T: t→ -t Since the second law of thermodynamics state that entropy increases As time flows toward the future ,in general the macroscopic universe Does not show symmetry under time reversal. 8

9. EXPERIMENT FOR THE EVIDENCE OF P SYMMETRY The WU experiment was a particle and nuclear physics experiment conducted in 1956 by the Chinese American physicist CHEIN WU purpose to establish whether or not conservation of parity also applied to weak interactions .If P-conservation were True, a mirrored version of the world would behave as the mirror Image of the current world. If P conservation were violated then It would be possible to distinguish between a mirrored version of the world and the mirror image of the current world. 9

10. The experiment monitored the decay of cobalt-60 atoms that were aligned by a uniform magnetic field and cooled to near absolute zero so that Thermal motions did not ruin the alignment . During this decay one of the Neutrons decays to a proton by emitting an electron and an electron Antineutrino .Gamma rays are photons and their release from nickel-60 nucleus is an electromagnetic process. This rate was measured over time and with the polarizing field oriented in opposite direction .Then there would have been evidence to suggest that parity was indeed Conserved by weak interaction. 10

11. CP VIOLATION CP violation was first discovered in the decay patterns of Kaon , a specific group of composite particles. Two of the decay paths of K-long KAON are particularly striking . The products of two decays are entirely CP-symmetric versions of one another . For example one involved an electron antineutrino and the other an electron neutrino and all other corresponding particles of the two decays were also entirely CP symmetric. However in experiment, the K-long was more likely to decay into the path involving the electron neutrino by a small fraction . It is the fractional difference that demonstrate clear CP violation. 11

12. Detecting cp violation in neutrino Since this discovery , CP symmetry violation has already been observed in quark mixing theory. (Quarks are elementary particles that make up photons, neutrons , KAONS and more). However, more CP violation must be observed in order to explain the Universe’s matter dominance. Therefore , physicists are looking to Find CP violation in other particles, such as neutrinos . 12

13. Neutrinos violate p-symmetry If you flip, i.e. mirror, a left handed neutrino, you get a right handed neutrino. The problem is, while we have seen plenty of left handed neutrinos, no right handed neutrinos have ever been observed. Here, mirroring causes the law of physics to change .This violates P-Symmetry. 13

14. Neutrinos violate c- symmetry If you take the charge conjugation of a left handed neutrino ,you get a left-handed antineutrino .This problem here is that left handed anti- Neutrinos have never observed either. And so C symmetry is v here too. 14

15. 15 CONCLUSION Symmetry in physics is the preservation of some feature under a transformation. These symmetries help to classify various interactions, and allow us to describe “patterns” of nature. 3. Symmetries help to apply constraints to physical laws and guide us to proceed for the new discoveries . Symmetry becomes even more useful due to its associated laws like conservation laws. 5. Symmetry helps to bring out the elegance to the Physics.

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