SLIDE 1
Volume ZEB, number 7 PHYSICS LETTERS 20 January 1969
NEUTRINO ASTRONOMY AND LEPTON CHARGE
- V. GRIBOV * and B. PONTECORVO
Joint Institute for Nuclear Research,
L?ubna, USSR
Received 20 December 1968 It is shown that lepton nonconservation might lead to a decrease in the Ember
- f detectable
solar neutrinos at the earth surface, because
- f VeZ VP oscillations,
similar to K
- Z K” oscillations.
Equations are presented describing
such oscillations for the case when there exist only four neutrino states. Recently there became known the results of fidence level of about 70%
- ne finds respectively
the beautiful experiment
- f Davis et al. [l],
in the following upper limits for the corresponding which deep underground a search was made of interaction constants zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
f 1, f 2, f 3
phenomenologi- sun neutrinos. tally responsible for such processes [e.g.12]. Using a spectrometer proportional counter [2,3] to detect 37A produced in the reaction v + 37Cl + 37A + e- [3,4], (which is expected to take place in 390000 litres of C2C14 ), Davis et
- al. so far were not able to detect solar neutrinos.
It was shown by them that the neutrino flux at the earth from 8B decay ivlthe sun [5] is smaller than 2 x lo6 cmW2 set
. This limit is definitely
smaller than the theoretical predictions [6,‘7]. However, various astrophysics and nuclear physics uncertainties do not allow to draw the conclusion that we are faced with a catastrophic discrepancy [7]. The purpose of this note is to emphasize again that the result of sun neutrino experiments are related not only to the above mentioned uncertainties but also, and in a marked way, to properties which are so far unknown [8]
- f the neutrino as an elementary
particle. The question at issue is: are (is) lepton charges (charge) conserved exactly ?. The question which, as we shall see, is relevant to neutrino astro- nomy, is certainly not far-fetched from an ele- mentary particle physics point of view. As a matter of fact the most significant and recent experiments
- n lepton conservation
give upper limits for the constants
- f hypothetical
interac- tions nonconverving lepton charge which are surprisingly large. fl/G < 0.02;
f
2/G < 0.15;
f$G <
0.005, where G = lO-5/M 2 constant. P is the Fermi weak interaction In a period of development
- f physics
in which such quantum numbers as P,
C, PC were found to
be not good, it is natural to question the exact validity of any symmetry [e.g. 131. The relative- ly high upper limits for f
1, f 2, f 3
show that there is once more plenty of room for a violated con- servation law and suggest the lepton charge(s) as the first candidate(s) for the nonconserved quan- tum number(s). In previous publications [8,14] there was shown that lepton nonconservation leads to the possibili- ty of ostiillations in vacuum between various neutrino states, and, generally speaking, acts in the sense of decreasing the number of detectable solar neutrinos with respect to the number ex- pected theoretically under ttie assumption that lepton charges are strictly conserved. The most accurate information can be obtained from the experiments, in which a search was made for the processes 48Ca -+ 48Ti + e- + e- [9], v/J + P -+ cc+ + n [lo], 1_1+
- + e+ + y [ll].
At a con- * Leningrad
Physical-Technical Institute Leningrad, USSR.
This effect, which incidentally would be in the right direction if the necessity should definitely arise of accounting for unexpectedly small values
- f detected solar neutrinos
is due to the fact that in the presence
- f oscillations,
part of the neu- trinos are sterile, that is practically unobserv- able. It turns out that the study of solar neutrino
- scillations
is the most sensitive way of investi- gating the question of lepton charge conservation. In ref. 8 possible
- scillations
ve 2 iTe, vpZ$, v,Zvj$ have been discussed. In view
- f applications