The Second Workshop on Grand Unification: University of Michigan, Ann Arbor April 24–26, 1981

329 Pages·1981·6.49 MB·English

by  Sheldon Lee Glashow (auth.)

The Second Workshop
on Grand Unification
University of Michigan, Ann Arbor
April 24-26, 1981
Jacques P. Leveille,
Lawrence R. Sulak, and
David G. Unger, editors
1981 Birkhauser
Boston • Basel . Stuttgart
Editors:
Jacques P. Leveille
Lawrence R. Sulak
David G. Unger
The Harrison M. Randall Laboratory of Physics
The University of Michigan
Ann Arbor, Michigan 48109
Library of Congress Cataloging in Publication Data
Workshop on Grahl Unification (2nd: 1981: University of Michigan)
The Second Workshop on Grand Unification.
1. Grand unified theories (Nuclear physics) --Congresses.
I. Leveille, Jacques P., 1951-
II. Sulak, Lawrence R., 1944-
III. Ungar, David G., 1951- IV. Title.
QC794.6.G7W67 1981 539.7'54 81-38522
CIP-Kurztitelaufnahme der Deutschen Bibliothek
Workshop on Grand Unification 02, 1981, Ann Arbor, Mich.:
The Second Workshop on Grand Unification / ed. by:
Jacques P. Leveille ... - Boston; Basel; Stuttgart:
1981
Birkh~user,
NE: Leveille, Jacques P. (Hrsg.); HST
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or by
any means, electronic, mechanical, photocopying, recording or
otherwise, without prior permission of the copyright owner.
~Birkh~user Boston, 1981
ISBN-13: 978-0-8176-3055-3 e-ISBN-13: 978-1-4612-5990-9
DOl: 10.1007/978-1-4612-5990-9
CONTENTS
FOREI'[ORD .•...... vii
A NEUTRINO-FREE UNIVERSE 1
S. L. G1ashow
THE KOLAR GOLD FIELD NUCLEON DECAY EXPERIl1ENT; A STATUS REPORT. 11
S. Hiyake and V. S. Narasimham
SEARCH FOR NUCLEON DECAY: THE DEEP UNDERGROUND WATER CERENKOV
DETECTOR AND THE HOMESTAKE TRACKING SPECTROMETER • . 22
R. 1. Steinberg
EXPERI~lliNTS AT THE SOUDAN MINE: OPERATING AND PROPOSED. • . .. 41
M. A. Shupe
THE J.!ONT BLANC FINE GRAIN EXPERU1ENT ON NUCLEON STABILITY. . .. 55
E. Fiorini
A FINE GRAIN DETECTOR IN THE FREJUS TUNNEL . . . . . • . . . .. 70
R. Bar10utaud
STATUS REPORT ON HARVARD, PURDUE, WISCONSIN PROTON DECAY
EXPERU1ENT • . 80
C. Wilson
IRVINE-MICHIGAN-BROOKHAVEN (I.B.H.) NUCLEON DECAY SEARCH:
STATUS REPORT . . . . . • . . . • • • . 84
D. Sinclair and T. H. Jones
REVIEW OF NEUTRON-ANTINEUTRON OSCILLATION EXPERUmNTS. . . . .• 98
K. Green
LIMITATIONS ON PROTON DECAY HODES FROM A PASSIVE DETECTION
SCHEME .• 120
C. L. Bennett
ULTIMATE LUlITS TO PROTON DECAY SEARCHES . . • . • . . . . . .. 125
J. G. Learned
THEORETICAL EXPECTATIONS FOR PROTON DECAY. . . • . . . . • . •. 131
P. Langacker
SU(5) THEORY vs. EXPERI~NT. 151
VI. J. Marciano
vi
EFFECTIVE LAGRANGIAN AND EFFECTIVE PARAlffiTERS IN
GRAND UNIFIED THEORIES 163
Y.-P. Yao
THRESHOLDS IN PARTICLE PHYSICS 179
M. Veltman
THE TeV PICTURE. 185
S. Raby
COMPLEXIONS OF BARYON AND LEPTON NillfBER VIOLATIONS
WITHIN MAXIMAL SYMMETRIES. 195
J. C. Pati
GRAND UNIFICATION AND THE FUNDM1ENTAL PROBLEMS OF
CLASSICAL COSMOLOGY. 222
M. S. Turner
CONSTRAINTS ON GRAND UNIFIED THEORIES FROM COSMOLOGICAL
BARYON ASYHHETRY . 248
M. Yoshimura
FIXED POINTS: FERMION MASS PREDICTIONS. . . . . . • . . . . .. 258
C. T. Hill
FERMION MASSES: ANOTHER LOOK. 265
Ii. Machacek
PETITE UNIFICATION: AN ALTERNATIVE VIEIWOINT. . . . . . . . .. 272
P. Q. Hung
SUPERSYMMETRIC TECHNICOLOR 282
H. Srednicki
SUPERSYHMETRIC GUTS. 285
S. Dimopou1os and H. Georgi
CONFERENCE Sill1MARY 297
S. Weinberg
WORKSHOP PROGRM1 317
LOCAL ORGANIZING COMMITTEE 318
ADVISORY C0l1MITTEE . 318
LIST OF PARTICIPANTS 318
FOREWORD
Recently there has been rapid progress towards understanding the
separate theories of the strong, weak and electromagnetic inter
actions within the framework of the standard SU(3) x SU(2) x U(l)
model. The purpose of the Second Workshop on Grand Unification
was to discuss the physics beyond the standard model and the major
topic was grand unified theories which unify the strong, weak and
electromagnetic sectors. Grand unified theories are presently being
used to calculate experimentally accessible quantities such as the
proton lifetime and nucleon decay branching ratios. Meanwhile,
experiments are currently being performed, and new, dedicated
experiments mounted, to measure these quantities. Reports on these
experimental and theoretical activities occupied much of the
workshop. Furthermore, since grand unified theories allow one to
extrapolate the behavior of the universe back to the first instants
after the big bang, their cosmological implications and the
constraints on these theories from cosmology were of great interest
at the workshop.
The conference opened with a keynote address by S. L. Glashow in
which he discussed among other topics baryon minus lepton number
conservation, neutrino masses and a neutrino-free universe. To
maximize the interplay between theorists and experimentalists,
theoretical and experimental talks were interleaved. An experimental
highlight of the workshop was the presentation by S. Miyake of three
candidate events for proton decay. The Indian-Japanese group working
in the Kolar Gold Fields has established that the inherent neutrino
background is as low as initially predicted and has measured a new
lower limit on the lifetime of the proton of 3 x 1030 years. The
current limits from the on-going experiments of the Minnesota group
at the Soudan Mine and of the Pennsylvania group at the Homestake
viii
Mine were presented by M. A. Shupe and R. I. Steinberg respectively.
The experiments of the Irvine-Michigan-Brookhaven,
Harvard-Purdue-\Usconsin, French, and Italian groups, which are all
in the proposal or construction phases, were detailed by D. Sinclair,
C. Wilson, R. Barloutaud and W. Fiorini respectively. These
detectors can potentially observe nucleon decay if the lifetime is
less than 1032 -1033 years. To extend the limit of observation to a
lifetime of 1034 years, J. G. Learned proposed a deep ocean detector.
Decay mode independent searches have been made with "passive"
detection schemes. C. L. Bennett presented a new, lower bound on the
lifetime of 2 x 1027 years from his passive technique.
Neutron-antineutron mixing is another possible consequence of some
theoretical frameworks, including several grand unified models. K.
Green reviewed the phenomenology of n-n mixing and the experiments
designed to observe its consequences.
On the theoretical side, P. Langacker surveyed the theoretical
expectations for baryon number violation within the context of grand
unified theories. W. J. Marciano presented the confrontation between
predictions of the SU(S) model and current data. There is presently
good agreement on the value of sin2Sw• Y.-P. Yao discussed the low
energy effective theories and parameters that result from unified
theories with widely separated mass scales. C. T. Hill and M.
Machacek pointed out possible new consequences of grand unified
theories on the low mass fermion spectrum. Schemes beyond the
standard model, but which do have new mass scales between 102 and
1014 GeV, were presented by M. Veltman, S. Raby and J. Patio The
novel idea of combining supersymmetry with technicolor to provide
answers to current difficulties, such as naturally explaining the
existence of an extremely large gauge hierarchy, was discussed by M.
Srednicki, H. Georgi, and S. Dimopoulos. P.Q. Hung outlined
alternative models in which the weak and electromagnetic interactions
have a single gauge coupling constant.
The consequences of grand unified theories for fundamental
problems in classical cosmology and vice versa were reviewed by M. S.
Turner. Within the unification framework the observed baryon
asymmetry may be understandable. Alternatively, the observed baryon
ix
asymmetry can be used to constrain grand unified theories as
explained by M. Yoshimura.
S. Weinberg concluded the workshop by placing the discussions of
the three days into perspective and by challenging the participants
with new issues in this exciting field.
In addition to the lectures and informal discussions,
conviviality was assured by an evening of imbibing, French cuisine
and excellent wines in an environment that included the Hall of
Dinosaurs at the Natural History Museum on the University of Michigan
campus. The down-to-earth nature of spontaneously broken symmetry
was demonstrated by the soap bubbles of L. Sander, and the
deep-under-earth nature of the experimental aspects of the field was
highlighted by a visual trip to the 1MB salt mine, courtesy of
Michigan Media TV.
The financial support for the workshop was provided by the
National Science Foundation, the Department of Energy, and the
Physics Department of the University of Michigan.
We want to thank the lecturers for their cooperation in
preparing this volume. All members of the local organizing committee
must be thanked for their hard work; in particular Gordy Kane for his
unfailing enthusiasm. We are grateful to Lois Kane for producing the
art used on the cover of this book. A special debt of gratitude is
due to Barbara Nieman whose efforts and patience in the months prior
to and during the workshop made this meeting the success that it was.
June 1981 J. P. Leveille
L. R. Sulak
D. G. Unger
A NEUTRINO-FREE UNIVERSEt
Sheldon Lee Glashow ,~
Center for Theoretical Physics
Massachusetts Institute of Technology
Cambridge, l!assachusetts 02139
The work I shall discuss was done in collaboration with H. Georgi
and S. Nussinov. References to the literature may be found in our
recent Harvard preprint, HUTP-8l/A026.
(1) Everything is allowed that is not explicitly forbidden. This
is not a Scandinavian sex law, but a perceived truth of elementary
particle physics. Hence, parity-violation, CP violation, and (soon)
baryon number violation. Nobody, convincingly, argues that neutrino
masses must vanish. In SUeS), when it is naively implemented, neutrino
masses do vanish. On the other hand, 0(10) (again naively implemented)
requires non-vanishing neutrino masses. In general, it is argued that
neutrino masses are small by the same factor that the unifying mass is
large. Grand unified theories suggest (but do not demand) neutrinos
with masses from electron volts to microvolts.
(2) Hints of neutrino mass. Recent papers address the possibility
that neutrinos have measurable masses, and indeed, that effects due to
these masses have already been seen. Here is a sampling of the
literature.
(3) Neutrinoless double beta decay. This process is induced by
the existence of a Majorana mass of the electron neutrino. Anciently,
Primakoff and Rosen argued that the experimental data excluded such a
mass if it were larger than 800 eV. More recently, stronger limits
. 76 82
have been deduced. From an analysis of data concernlng Ge and Se
decays, Haxton, et al. conclude that the Majorana mass of the electron
tThis research is supported in part by the National Science Foundation
under Contract No. PHY77-22864 and the D.O.E. Contract DE-AC02-76ERO-
3069.
*
On leave from Harvard University.
2
neutrino must be less than 15 eV. In an independent study of the BB
128 130
decays of Te and Te, Doi, et al. conclude that the Majorana mass
of the electron neutrino is 41 ±l eV. These two studies are only in
apparent contradiction. The model of neutrino masses we shall discuss
is compatible with both results.
(4) Endpoint spectra. A finite neutrino mass will affect the
shape of the electron spectrum in beta decay near its endpoint. In a
recent Soviet study of tritium decay, evidence for a non-zero neutrino
mass has been claimed: l4eV < m < 46eV. The interpretation of this
experiment is clouded by uncertainty due to atomic and molecular
corrections which are comparable to the alleged effect. Clearly,
further studies of tritium are required, and in a simpler atomic
environment than as a constituent of valine. Another promising endpoint
study that may reveal the neutrino mass involves inner bremsstrahlung
in electron capture. Such experiments have been recently proposed,
discussed, and initiated by De Rujula and his collaborators.
(5) Neutrino oscillations. Massive neutrinos may (but need not)
display the phenomenon of neutrino oscillations, wherein one kind of
neutrino becomes another. These phenomena may be parameterized in
terms of (three or more) neutrino masses and (four or more) neutrino
mixing parameters. Large mixing angles and large masses have been
ruled out by experiment. However, there are two weak experimental
indications that neutrinos do oscillate. One is the well-known solar
neutrino deficit. This could be explained by small neutrino masses
(at least microvolt) and large mixing angles. With three neutrino
species, the maximum suppression of solar neutrinos is by a factor of
0.33, and a random choice of angles gives a mean suppression of 0.60.
The Gallium experiment, as proposed by Bahcall and as initiated by
Davis, can reveal whether the observed solar neutrino deficit is a
problem for solar physics or for particle physics. The second positive
indication for neutrino oscillations, a reactor experiment, was
announced by Reines et al. a year ago. Confirmation of this result,
as yet, is lacking. Several very sensitive searches for neutrino
oscillations are in various stages of planning or implementation at
present. It is a subject of primary interest and importance.
(6) Galactic Haloes. At various levels, there are indications of
the existence of substantial amounts of non-luminous mass in the
universe. For example, the rotation curves of galaxies show (almost
without exception) the existence of massive invisible galactic haloes.