Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
The decay φ → ππγ as a means for detecting S wave resonances and C violation 
Publisher
Date
1965
Subject
Type
Identifier
Physics Letters 17(1), 77-78 (1965)
Database
Language
Show preview
Hide preview
Volume 17, number l PHYSICS L E T T E R S 15 June 1965
THE D E C A Y AS A M E A N S FOR D E T E C T I N G S W A V E R E S O N A N C E S AND C V I O L A T I O N
J. PRENTKI and M. VELTMAN CERN, Geneva
Received 17 May 1965
In this note we would like to point out that a careful study of the decay can give interesting information on both even spin re- sonances with isospin 0 and the possible exis- tence of C violating effects in strong interac- tions [1,2].
Suppose that C is conserved to a high degree in strong and electromagnetic interactions. Re- membering that spin, parity, G parity, isotopic spin and intrinsic C of the are 1, -, -,0 and -
respectively, we note that the decay must proceed with the two pions in a state of even angular momentum, i.e., Thus this reaction furnishes us a sample of events with pions in an even wave (and spin 0), which is ex- tremely well adapted for study in the region where otherwise P waves (p-resonance) would be important.
Recently, some evidence was presented [3] in favour of a large wave resonance called
77
Volume 17, number 1 PHYSICS L E T T E R S 15 June 1965
, around 720 MeV. Especially for this mass, separation of and is usually quite difficult, but in the the would show up as a clear bump in the invariant mass spectrum *. The angular distribution of with re- spect to the -line of flight can give Information on the spin of such a resonance. Of course ABC and a resonances could be studied here also.
The recently proposed [1] possibility of C violation in strong interactions could be tested here. If C is violated may proceed with the pions in a state of odd angular momen- tum. One expects then a bump (due to the p) around 760 MeV of a P wave nature. It may be noted that in any case this p is depressed by a factor 10 -1 - 10 -2 associated with the C violating interaction. Again study of the angular distribu- tions of or could reveal the characteristic features of aP wave. This C violating effect could be seen rather easily through the inter- ference with the C conserving S wave mode
the and angular distributions and energy spectra would be different from each other, and for instance the number of with energy larger than that of the would be differ- ent from the number of with energy smaller than the energy.
Concerning the branching ratio of we may remark that it should be quite appreci-
* Of course, can be established also by looking for a resonance in the system.
able - at least 10-20%. The reason for this is that other modes are quite suppressed: the decay
has a very small phase space (Q = 23 MeV), and is suppressed by SU(6). Also
is forbidden by SU(6) symmetry. Similar remarks can be made for the process
(branching ratio known to be about 3%), although the situation is more difficult due to the smaller phase space. The or bumps would be on the end of the mass spectrum, corresponding to the low energy part of the spectrum. But any reasonable production mechanism will also favour low energy which makes the or identifi- cation less easier. Any C violation may still show up as differences in and distributions. A factor in favour of the is of course the larger production cross section.
We wish to thank Professor G. Puppi for a helpful discussion.
References 1. J.Prentki and M.Veltman, Physics Letters 15
(1965) 88; T.D.Lee and L. Wolfenstein, preprint; B.Okun, preprint.
2. The C violating aspects of and are also discussed by Y. Fujii and G. Marx, Physics Letters 17 (1965) 75.
3. L.Durand and Yam Tsi Chiu, Phys. Rev. Letters 14 (1965) 329.
THE D E C A Y AS A M E A N S FOR D E T E C T I N G S W A V E R E S O N A N C E S AND C V I O L A T I O N
J. PRENTKI and M. VELTMAN CERN, Geneva
Received 17 May 1965
In this note we would like to point out that a careful study of the decay can give interesting information on both even spin re- sonances with isospin 0 and the possible exis- tence of C violating effects in strong interac- tions [1,2].
Suppose that C is conserved to a high degree in strong and electromagnetic interactions. Re- membering that spin, parity, G parity, isotopic spin and intrinsic C of the are 1, -, -,0 and -
respectively, we note that the decay must proceed with the two pions in a state of even angular momentum, i.e., Thus this reaction furnishes us a sample of events with pions in an even wave (and spin 0), which is ex- tremely well adapted for study in the region where otherwise P waves (p-resonance) would be important.
Recently, some evidence was presented [3] in favour of a large wave resonance called
77
Volume 17, number 1 PHYSICS L E T T E R S 15 June 1965
, around 720 MeV. Especially for this mass, separation of and is usually quite difficult, but in the the would show up as a clear bump in the invariant mass spectrum *. The angular distribution of with re- spect to the -line of flight can give Information on the spin of such a resonance. Of course ABC and a resonances could be studied here also.
The recently proposed [1] possibility of C violation in strong interactions could be tested here. If C is violated may proceed with the pions in a state of odd angular momen- tum. One expects then a bump (due to the p) around 760 MeV of a P wave nature. It may be noted that in any case this p is depressed by a factor 10 -1 - 10 -2 associated with the C violating interaction. Again study of the angular distribu- tions of or could reveal the characteristic features of aP wave. This C violating effect could be seen rather easily through the inter- ference with the C conserving S wave mode
the and angular distributions and energy spectra would be different from each other, and for instance the number of with energy larger than that of the would be differ- ent from the number of with energy smaller than the energy.
Concerning the branching ratio of we may remark that it should be quite appreci-
* Of course, can be established also by looking for a resonance in the system.
able - at least 10-20%. The reason for this is that other modes are quite suppressed: the decay
has a very small phase space (Q = 23 MeV), and is suppressed by SU(6). Also
is forbidden by SU(6) symmetry. Similar remarks can be made for the process
(branching ratio known to be about 3%), although the situation is more difficult due to the smaller phase space. The or bumps would be on the end of the mass spectrum, corresponding to the low energy part of the spectrum. But any reasonable production mechanism will also favour low energy which makes the or identifi- cation less easier. Any C violation may still show up as differences in and distributions. A factor in favour of the is of course the larger production cross section.
We wish to thank Professor G. Puppi for a helpful discussion.
References 1. J.Prentki and M.Veltman, Physics Letters 15
(1965) 88; T.D.Lee and L. Wolfenstein, preprint; B.Okun, preprint.
2. The C violating aspects of and are also discussed by Y. Fujii and G. Marx, Physics Letters 17 (1965) 75.
3. L.Durand and Yam Tsi Chiu, Phys. Rev. Letters 14 (1965) 329.
Comments
