1

1111111~11~I~~l~i~l~~ij~I1~~~II~ o llbD 0026270 3 The yeiU 1993 il a bampnner anniveuary ior our understanding of nature it marks the

Weak Neutral Currents in Nature a Thirty Year Retrospectivemiddot

David B Cline Center for Advanced Accelerator

Department of Phllsia amp Astronomy University of California Los Angdes

OS Hilgard Avenue Los Angeiu CA 900f-157 USA

UCLA-PPH0052-893 2 Abtract

Neutral Currentl play an important role in nature We trace the early history of Neutral Char~ed Weak Current studia from tbe 1930 to the dilcovery of the Wand Z in 1983 In the 1960s the null search (or Neutral CUrrenti that chan~e Family combined with modell of Weak Neutral and Char~ed Currentl and led to the concept of Natural family Conaervation in Neutral Cunentl In rapid order Weak Neutral Currents (WNC) were discovered in 1973 were well understood by 1978 and were followed by the dicovery o( the Wand Z in 1983 Neutral Currentl (NC) are important in Supernova ExploeioRi and the Early Univene The March (or NC that chan~e Family extend our study o( the subatomic world into the incredible range o( 100TeV and it on-going today The super colliders SSC at Dallu USA amplid LHC in Geneva SwiLlerland will allow us to ex~nd thit March considerably

The Early Concepts of the VB and Neutral Currents

As is weU known the weak interaction wu accidentally discovered by H Beckerel in 1896 when he placed Uranium and a photographic emulsion in the same drawer only to observe the emulsion had become expOied This wu the discovery of the charged current weak interaction It took 77 yeamprl longer to discover the neutral current weak interactions in 1J73 In the intervening yean there were repeated suggestions that there could be a neutral current interaction The earliest explicit suggestion leems to have been made by Gamov and TeUer in 1937 In the 1950s and 1960s there were many modea of the weak force that included a neural component In Fig 1 we illutrate many of the proposals for extensions of the WeiLk Interaction and the Intermediate Vector Boaon (IVB) concepts[IJ

After the point interaction of Fermi in 1932 the first attempt to unify the charged and neutral current interaction seems to have been carried out by Oscar Klien in H138 However the real search for WNC started in the early 1960s in rare l decays[2J As illustrated in Fig I there were many theore~ical models that suggested that neutral currents may exist Thus there was no reallaclc of motive to search for WNC but a strong general theoretical prejudice against the search In Fig 2 I attempt to give a history of the search and discovery of various forms of neutral currents[lJ

oPrfpued for the EPS9 Trend in Phyics ConCereBce Florence September 1993

-0

10th anniversary of the dicovery of the carriera of the Weak force the Wand Z particles at CERN the laboratory near Geneva Switzerland the 20th anniversary of the discovery of the Weak Neutral Currents and the 30th anniversary of the first revealing but null searches for Weak Neutral Currentl that change the Quark Family All of these developments have left a profound mark on our study of the most fundamental aspects of nature the Elementary Particles and their Forces These observations helped develop the foundation of the Standard Model of Elementary Particles This article is a partial cele~ration of this anniversary and an attempt to peer into the future implications and gain a perspective 011

these accomplishment A in the telling of the history of any human accomplishments it will appear more logical than when it actually occurred We wiU also describe how the intervening yean have taught UI the way in which Neutral Currents contribute to Atrophysic and the ExplOlion o( Supernova wiU help in future possible breakthrou1hs in the study of Elementary Particles and possibly even the very nature of life on Earth the double helix structure of DNA present in all life forms

It can now be said the there have been three major advances in Physics during the past 100 or so yean The Theory of Relativity can be dated as taking place during 1905 1919 the development of Quantum Mechanics between 1913-1930 the experimental anu theoretical formulation of the Standard Model of Elementary Particles ( ruse of the Stan dard Model) which began around 1960 and continued until approximately 1983 Of course there have been many other important advances in Nuclear Physics Condensed Matter Physics Cosmology and so forth However the three advances mentioned above are distinguished by having led to a nearly complete picture of to major area of fundamental science that has stood the telt of tIme and verification by many experiments The period of the ltise ur the Standard Model was full of major theoretical and experimental discoveries tmong the mOlt important event during this period Wal the discovery of Neutral Currents (NC) in 1973

AU thr~ of the break-through mentioned above have one thing in common the basic theory has been greatly tested by experiment very early For General Relativity the observed deflection of Starlight by the Sun in 1919 was a crucial experiment For the Quantum Theory it was the study of various Atomic Physics systems as weU as the observation of the particle like nature of light (Compton Effect) and the wave like-nature of matter (2middotSlit Electron Interference Pattern) For the Standard Model of Elementary Particles the key period of experimentation was between 1974 and 1978 It was during this period that the newly discovered Neutral Currents were quickly confirmed and studied in numerous experiments around the world Given the breadth of the physical phenomena involved this was a truly remarkable period

To trace the history of the Weak interaction it is necessary to place particular emphasis on the discovery of NC and the underlying theory of the Standard Model The impact of the discovery of NC on our understanding o( nature could turn out to be as important as that of the Weak Interaction or Radioactive Decay which was discovered uy If Bequercl in 1896 and which we now know to be a Charged Current interaction in contrast to the Neutral Current By 1933 thirty-seven years later the source of the ener~y of the Sun was shown to come from the Weak Interactions by Hans Bethe of Cornell Univprsity i1lustratinc the great sigruficance of that dscovery

r 1

2 The Search for WNCs in the 1960

tn Tible 1 we report the important milestones for the lUrch for WNC in the 19605[lJ There were many zigl amplid Zagl in the aearch due to the ampreat difficulty of refiect ing varioul backgrou ndl

In 1963 a CERN neutrino KToup publiahed a very low limit on WNC from their neutrino experiment of 003 (CERN Group PhYlia Letters 1964)[3J See Fig 3a (reproduced from the original article) Thil incorrect result diminished the prospectl for detecting WNC and discouraged some group (iDcluding a Wicown heavy liquid bubble chamber group) from searching for WNC in other propoMd neutrino experiment On the other hand WNC could have been discovered in 1964 thu altering the hitory in thll field considerably

The null resultl o( the WNC search reinforced much of the theoretical prejudice o( the time once again Ihowing that IOmetimes experimentaliat rely too heavily on the guidance of theory On the other hand the earch for WNC In the HPWF experiment benefited from S Weinbergs advice and it was for that reuon that an energy trigger was installeu ill mid 1972 in that experiment

However even after the Weinbe~-Salam Model wu gaining acceptance the null results on WNC searches continued In Fig 3b I how the early limits on exclusive WNC channels up to 1972 when the limit were still well below the now measured values This illustrates how difficult the discovery o( WNC really wuflJ

3 The Significance of the Search for FCWNC in the 1960s

The concept of flavor was not well understood In the early and mid 1060 and it appeared that as good a technIque at any to search (or WNC wu to study rare K decays One of the earliest experiments set a Limit of 10-8 on[4J

J(+ - 1+ e+ e-

The Limits on FCWNC were summarized in a report I wrote in 1967 (see Fig 4a) which incl uded K - IJI- and the ampearch K+ - 11+ vii (rom my early work[5J

In 1965-1970 a crucial search for

[(+ 1+ vii

was started This search wu a pure FCW NC process whereu all other searches had charged particles in the final state and may have been affected by electromagnetic interaction as some people claimed The history of the arch (or this decay mode is given in Fig 4b it continues today (see Fig 41 at well)[I 4]

By 1970 the correct CERN limit on WNC amplid the extremely strong Limits on FCWNC caused most people to believe that neutral current did not exist in nature The GIM model was invented and showed that[6]

1 FCWNC could be suppressed in certain models

2 r hadron-lepton symmetry existed

Today the GIM mechanism hu only been tested (or Light quarks Chonn and n quarks are a rich ground in which to continue the search (or FCWNC and the search (or FC WNC has ~tarted there

3

The concept of flavor wu not weU undentood in the early and mid 1960 anu it apptared chat u good a technique U ampny to learch for WNC wu to study rare h uecaYI One ur the earliest experiment set a Limit o( 10-8 on

K+ - + e+ e-

The Limitl on FCWNC were lummarized in a report I wrote in 1967 (Fig 3b) which included K - IJIJ and the search K+ -- 1+ vv from my early work31

In 1965 - 1970 a crucial seuch for

K+ -- + vv

wu tarted Thi search wu a pure fCWNC process whereas all other searches had charged particlel in the final Itate and may have been affected by electromagnetic interactions as some people claimed The history of the search for this decay mode is given in Fig middotIa it continues today (see Fig 4b as weU)[3 7J

By 1970 the incorrect CERN limit on WNC and the extremely strong Limits on FCWNC caused most people to believe that neutral currents did not exist in nature The GtM model wu invented and showed that

1 FCWNC could be suppressed in certain models

2 A hadron-lepton symmetry existed

Today the GIM mechanim has only been tested for light quarks Charm and B quarks are a rich ground in which to continue the search for FCWNC and the search for FCWNC haa started there[8J

4 The 1973 Period The HPWF Experiment

In 1973 the HPWF experiment at fNAL turned on[9) Almost at the start 1Jmiddotlessmiddot neushytrino events were oberved Rumors of similar events at CERN set into motion an intense competition[10J The HPWF group actually performed 2 complete experiments in 1973 and after considerable confusion the issue was (ully resolved by December of t hat year The early limit on WNC and the strong limits on FCWNC played a role in the H PWF groupi confulion However along with the GGM evidence the existence of WNC was fully established at thi point in 1973 The book and reports by Peter Galison gives an accurate Account o( thil period of hitory in my opinion[1l]

By 1973 when the Fermi National Accelerator Laboratory (FNAL) neutrino beam was jUlt being cornmi8lioned and a luge detector built by the experimental groups from Harvard Penn and Wisconsin (HPW) the very luge bubble chamber GargameUe was taking corious data at CERN the illue o( the existence of NC was coming to a boil It was in this year starting with Gargamelle and the HPW experiments that NC were observed (see Table 1) I was privileged to be the spokesperson for the HPW experiment and have the opportunity to live through the trials and tribulations of t he discovery of neu tral curren ts hay ing created some o( them myself The other senior members of the HPW team were AK ~1ann of Penn and C Rubbia of Harvard

The discovery o( NC was not easy and the two experimental groups that were involvfd in the action in 1973 were anything but placid In contrast the early search for WNC was plagued with incorrect but placid results as recorded in Table 1 There were rll mors

-t

2 The Search for WNCs in the 1960

tn Tible 1 we report the important milestones for the lUrch for WNC in the 19605[lJ There were many zigl amplid Zagl in the aearch due to the ampreat difficulty of refiect ing varioul backgrou ndl

In 1963 a CERN neutrino KToup publiahed a very low limit on WNC from their neutrino experiment of 003 (CERN Group PhYlia Letters 1964)[3J See Fig 3a (reproduced from the original article) Thil incorrect result diminished the prospectl for detecting WNC and discouraged some group (iDcluding a Wicown heavy liquid bubble chamber group) from searching for WNC in other propoMd neutrino experiment On the other hand WNC could have been discovered in 1964 thu altering the hitory in thll field considerably

The null resultl o( the WNC search reinforced much of the theoretical prejudice o( the time once again Ihowing that IOmetimes experimentaliat rely too heavily on the guidance of theory On the other hand the earch for WNC In the HPWF experiment benefited from S Weinbergs advice and it was for that reuon that an energy trigger was installeu ill mid 1972 in that experiment

However even after the Weinbe~-Salam Model wu gaining acceptance the null results on WNC searches continued In Fig 3b I how the early limits on exclusive WNC channels up to 1972 when the limit were still well below the now measured values This illustrates how difficult the discovery o( WNC really wuflJ

3 The Significance of the Search for FCWNC in the 1960s

The concept of flavor was not well understood In the early and mid 1060 and it appeared that as good a technIque at any to search (or WNC wu to study rare K decays One of the earliest experiments set a Limit of 10-8 on[4J

J(+ - 1+ e+ e-

The Limits on FCWNC were summarized in a report I wrote in 1967 (see Fig 4a) which incl uded K - IJI- and the ampearch K+ - 11+ vii (rom my early work[5J

In 1965-1970 a crucial search for

[(+ 1+ vii

was started This search wu a pure FCW NC process whereu all other searches had charged particles in the final state and may have been affected by electromagnetic interaction as some people claimed The history of the arch (or this decay mode is given in Fig 4b it continues today (see Fig 41 at well)[I 4]

By 1970 the correct CERN limit on WNC amplid the extremely strong Limits on FCWNC caused most people to believe that neutral current did not exist in nature The GIM model was invented and showed that[6]

1 FCWNC could be suppressed in certain models

2 r hadron-lepton symmetry existed

Today the GIM mechanism hu only been tested (or Light quarks Chonn and n quarks are a rich ground in which to continue the search (or FCWNC and the search (or FC WNC has ~tarted there

3

The concept of flavor wu not weU undentood in the early and mid 1960 anu it apptared chat u good a technique U ampny to learch for WNC wu to study rare h uecaYI One ur the earliest experiment set a Limit o( 10-8 on

K+ - + e+ e-

The Limitl on FCWNC were lummarized in a report I wrote in 1967 (Fig 3b) which included K - IJIJ and the search K+ -- 1+ vv from my early work31

In 1965 - 1970 a crucial seuch for

K+ -- + vv

wu tarted Thi search wu a pure fCWNC process whereas all other searches had charged particlel in the final Itate and may have been affected by electromagnetic interactions as some people claimed The history of the search for this decay mode is given in Fig middotIa it continues today (see Fig 4b as weU)[3 7J

By 1970 the incorrect CERN limit on WNC and the extremely strong Limits on FCWNC caused most people to believe that neutral currents did not exist in nature The GtM model wu invented and showed that

1 FCWNC could be suppressed in certain models

2 A hadron-lepton symmetry existed

Today the GIM mechanim has only been tested for light quarks Charm and B quarks are a rich ground in which to continue the search for FCWNC and the search for FCWNC haa started there[8J

4 The 1973 Period The HPWF Experiment

In 1973 the HPWF experiment at fNAL turned on[9) Almost at the start 1Jmiddotlessmiddot neushytrino events were oberved Rumors of similar events at CERN set into motion an intense competition[10J The HPWF group actually performed 2 complete experiments in 1973 and after considerable confusion the issue was (ully resolved by December of t hat year The early limit on WNC and the strong limits on FCWNC played a role in the H PWF groupi confulion However along with the GGM evidence the existence of WNC was fully established at thi point in 1973 The book and reports by Peter Galison gives an accurate Account o( thil period of hitory in my opinion[1l]

By 1973 when the Fermi National Accelerator Laboratory (FNAL) neutrino beam was jUlt being cornmi8lioned and a luge detector built by the experimental groups from Harvard Penn and Wisconsin (HPW) the very luge bubble chamber GargameUe was taking corious data at CERN the illue o( the existence of NC was coming to a boil It was in this year starting with Gargamelle and the HPW experiments that NC were observed (see Table 1) I was privileged to be the spokesperson for the HPW experiment and have the opportunity to live through the trials and tribulations of t he discovery of neu tral curren ts hay ing created some o( them myself The other senior members of the HPW team were AK ~1ann of Penn and C Rubbia of Harvard

The discovery o( NC was not easy and the two experimental groups that were involvfd in the action in 1973 were anything but placid In contrast the early search for WNC was plagued with incorrect but placid results as recorded in Table 1 There were rll mors

-t

5

Inlt1 rumon or rumon puing back and (orth ampCrOi th AtiampDtic btween Batavia iilinoil ( II P W) to Geneva Switzerland (GarSampmelle) Some ot the rneaas were even being curled by members of one or the other team inee both sroup had an international constitution

The first to report a pOlitive result wu the Gargamelle Bubble Chamber group But the HPW group fint data twng in 1973 howed a very large excess of the NC events and an early scientific paper wu sent to a journal a few days after that of Its European rival Unfortunately the paper lent by the HPW group wu returned by the papers referee for clarification ~though it wu Iater publi hed

During the discovery period of 1973 a complex set of event occurred Fig 2 shows an attempt to represent this sequence For a more complete description one can recommend the book and various articles by Peter Galison who hu made a careful study of the historical events

The Period Between 1973 -1983

During the period between 1973-1977 an incredible ynthesis occurred The value of

sinl9W = 025 plusmn 004

consistent with the present data from LEP of

lin 1 9w = 0230 plusmn 0002

was measured All the data was described by two parameters sin l 9w and p and many different types of data were involved Fig S gives an account of this period by the value of sin z Ow that was being measured[l]

In 1977 parity violation in atoms wu dicovered at NovOlibink and in 1978 at SLAC The full SU(2) X U(l) model had been accepted by the hlgh energy community by 1978 Thus in a four year eriod WNC were undertood whereu the correaponding understanding of charged currents took more than 30 yean

In 1976 an idea wu put forwud by C Rubbia of CERN P McIntyre of Texas Aamp M and the author to convert either the CERN or FNAL Synchrotron to a protonmiddotantiproton collider in order to discover the W and Z partldeI[12 In 1983 the W and Z were discovered at CERN the pinnacle of the Rise of the Standamprd Model

While the pamprampmetera of WNC were being undertood in the incredible period of just 3 - years several of us stamprted to plan how to detect the Wand Z bosons The pp coUider idea had been born in 1976 and the Wand Z dicovered in 1983 (Some of the members of the HPWF team were part of that discovery)

During the period of 1975-1978 the value of in2 9wstabLized to the level of 022-0 25 implying a mass of the W and Z in the range of (7885) and (8292) GeV (see Fig 5) At t rus point it wu realized by Cline Rubbia and McIntyre that a tiP collider with the center of mass energy of 600GeV or greater could be used to discover the Wand Z which they proposed This concept wu carried out at CERN where the Wand Z were discovered in 1983 (This wu the subject of another conference at UCLA in 1993)

The completion of the Rise of the Standard Model occurred during the period of 1974shy1978 when the WNC parameiera ainl 9 and p were measured in different reaction and found to be the aarne values within erron The role of the null searches for FCNC on the Standard Model ia iUutrated in Table 2 The example of the measurement of sinl 9 is shown in Figs 530 and 5b Future studies of Atomic Parity Violation may reach the same

)

lv-e of pieiiiiOii LEP _itG thi be vabc to ~each fc~ phy~ c b~yc nlt the st and~d

model

6 The Future

The future study of elementary particlel depends partially on two (actors (1) the detailed and precie meuurements qf NC puarneters and (2) the continued search FCNC LEP in Geneva Switzerland i being used to study the ZO by the millions and has improved our knowledge of the NC parameteu The key to future meatlurements are the Radiative Correction to the Standard ModeJ So far IlQ direct evidence for Radiative loop corrections haa been obtained from the several million ZO studied at LEP Fig 630 shows the kind of tools that will be used in the future to refine these measurements Dy the year WOO sin~ Bu may be known to better than four decimal points an incredible accomplishment in 25 years of study

The search for Neutral Currents that change Quark Flavor (FCNC) is also enterin g in to a sensitive period Fig 6b shows one such experiment where the b ( Beauty) q ll ark lo 5

(S trange) quark transi tion

+ XO (I) -i+l

is being searched for We can consider the XO particle to indicate a new level of suustruclurc in physics The most senlitive search to date was carried out at the CERN pp collid er by the authors group [13J The current limits in FCNC are shown graphicaily for several important processes in Fig 6c and 6d The other interesting FCNC process (s quark to d ( Down ) quark)

d + X O (2 ) - I + Ii

can be searched for by the reaction

h+ + + I + ii (3)

Thi search was started in 1965 by the author in order to search for a clean example of FCNC and continues today (see Fig 6c) The level of sensitivity to the mass of the Yu particle has now reampehed well beyond 10TeV the Superconducting Super Collider (SSC ) energy Future experiments can extend the range to 100 and even possibly 1000TeV far beyond that available to the SSC or LHC Super Colliders Fig 630 and b show the histo ry of the limits on the search for FCNC both in the rates (b) and amplitudes (a)[ 13)

While the earliest searches for Flavor Changing Neutral Currents used the decay of K mesons and failed to observe neutral currents we now know that these null result s are a key component of the Standard Model In the simplest version there is a sort of Flavor Conservation built into the Neutral Currents which in turn prescribes that oill y two types of quarks should exist in nature charges Q = -1 3 and Q = 23 In oth er words one of the great successes of the Standard Model is the inabi li ty to observe Neutral Currents thiLt change the Flavor of the Quark (Table 2)[lJ In contrast the observat loll of even a tiny FCNC signal would imply structure beyond the Standard Model

What can We hope to discover with such precise measurements of NC or searches for FC NC A process that goes beyond the Standard Model to possibly iUuminate the physics

r

SOME MILESTONES IN THE SEARCH FOR WNC (1962 - 1973) (D CUne)lJ

wuting tbere We strongly bellev ha hrbull bull hould b som new lubstructure in the energy range from the W ampnd Z to he Planck Scale - lOI8GeV AI illultrated In Fig 7 t he Rise of the Standard Model had many playerl With the current excellent agreement between the LEP (5 million ZOs) and the Standud Model the search for FCNC is even more important

References

[IJ Proceedings o( the Intern Symp on 30 Year of Neutral Currents from Weak Neutral Currents to the (W) Z and Beyond to be publilhed by AlP editors D CUne and AK ~fann O Klein in Proc Symp on Lei NouveUes The de 130 Physique Warsau 1938 (Illst Int de Cooperation InteUectueUe Paril 1939) p G O KI~in Nature lil1ll7 ( 1948)

[21 D CUne The Search for Weak Neutral Cummts Proc o( Ecol Int Hecg Novi (196i) and Thesis at Univ o( Wisc (1965 ) U Camerini et aI Phys Rev Lett 11318 (1964)

[3J MM Block et aI PhYI Rev Lett 12 (1964 )

[~J U Cameriru et aI PhYI Rev LettlJ318 (1964)

[5J D CUne The Search (or Weak Neutral Currentl Proc o( the Ecole Inter Becg Novi (1967) and the Thesis at Univ of Wisconsin (1965)

[61 SJ Gl~how J lliopuloul and L Maiani Phys Rev Dl1285 (1970)

[7] J Klems et aI Phys Rev Lett 2i 1086 (1970)

[8J SL Glashow Nucl Phys 22 579 (1961) S Weinberg Phys Rev Lettll1264 (1967) A Salam Proc 8th Nobel Symp Alpenugarden 1986 ed N Svartholm Pub by Almqvilt and Wisell STockholm 1968 p 367

(9J First report of the HPWF evidence (or WNC wu reported at G Myatt Proe of 1973 Bonn Conf Germany (see Comment In the question Iession) A Benvenuti et al Phys Rev al 800 (1974) (submitted (or publ Aug 3 1973) [this paper was returned by t he referee with questions it wu no withheld from publication this was the first experiment by HPWF in early 1973J

[iOJ Hasert et aI P hys Lett IHsect 138 (1973)

[IIJ P Gali50n How Experiments End Univ of Chicago Pres (1987) and The Discovery o( Weak Neutral Currentl in 50 Yean of Weak Interactions Proe of the Wingspread Conf Editors D Cline and G Rieduch Univ of Wise Phys Dept Book (1984)

[i2J A Benvenuti et al Phys Rev Lett n 189 (1976) C Rubbia P Mcintyre D Cline Proe o( Aachen Neutrino Conf 1976 ampnd subsequent reports by Cline Rubbia and othel1 (1976-80)

[13J D Clioe The Search for Rare B Deay and B - BO Mixing Pub in the Proe of l he 3rd Topical Seminar on Heavy Flavon San Miniato Italy 1991 and Proe o( the meeting on Rare Band K Decay and Novel Flavor Factories AlP Book July 1992

Ta ble 1

MILESTONES

1962 BNL Neutrino Experiment Detects 2nd Neutrino Unusual Events noted in PhD students Thesis (Little Crappers)

1964 CERN Bubble Chamber Group(a) Reports a limit of 3 for WNC

1967 EC Young Thesis at Oxford notes Neutral Current-like EventJ exist in Data

1967 Large Heavy Liquid Bubble Chamber studied by the MURA-WiscmiddotUCB Group to Search (or WNC (II - II) at ANL Later Proposed (or BNL then Rejected Proposed for BNL then Rejected

1969 HPW Experiment Proposed shyOnly Mention of Neutral Currents is for Leptoruc Processes

1970 CERN Group Rev ises 64 Limit (b) on WNC to 12

1972 Schwartz- Mann-SLAC Black Hole Experiment finds Some Neutral C urrent-like Events

1972 Perkins Reports Limits on WNC at FNAL Meeting

1973 GargamelJe HPW

(a) M M Block et 0 Phy bull Rev Lett J (196-1) (b) D Cundy et 01 PhYl Lett 31lJ -1 79 (19 70)

8

COMMENTS

Strange events are likely incorrect associated with neutrons from the shield

Reason for this incorrect limit later given in 1970 paper

Gargamelle Bubble Chamber already approved Incorrect CERN limits on WNC Discourage other Experimenters

64 Limit on WNC Makes Search for T his Process Difficult so Leptonic Processes Considered

Too Few Events to make Conclusi ve Arguments

Limit still Below Currently Observed Values

StruKgle with Large WNC Signal (see Ref 12)

Table 2

IMPACT OF FCNC SEARCH ON THE RISE OF THE STANDARD MODEL

PROCESS fWQ1l

~+d (K+ - lI+vv)

1963

1970

0 _

+ Loop-jd 10 KJ - IL mixing

1960 - j4

+d cf-u etc

1970s

b-fd b -j1J SO - lJo ixing

1980

STRONG LIMITS ON

lJf-d b-fd vf-v~

K - IJ

1990s

IMPLICATION

FCNC Absent at first level of Weak Interaction [GIM Mechanismj

New quark in Loop m 2 Ge V (Charm)

Natural Flavor Conservation for NC impU only Q = -13 Q =23 quarks ex1It In double in nature

Neceuary existence of (maasive) t quark

Limit on supenymmetric interaction and other exotics

INTERMEDIATE VECTOR BOSON HISTORY

16

14

12

10

~

aI

o

~

111 ~

o or

NI

ii c

0

~ ~ el shy

--~ 0 0ltgt

= eE j0 o c

r-

c ~ gtC

o ~

rshy

bull

0 ~~ a EE Eel n~ ~

0shy-ltIt -ltIc

l _ E

~ ~~

~~ ee C

t1~en2 c

i~c~ l~ J- ~CD

1963

Fig 1 Intermediate vector boson his tory

q

1938 1957

c o

~ (ij

c (3 en CTI

o ltXI

~ N

CTiI ~l - 0

c

0 u E

f

j ~ gt- ~

c 0 o 3shyIoU

obull

c o

-sect rn

1960

o o

bull

c o

~

1960

~ (]I

2

_

l

f ~

c co

~ (]I

c o ~ CZ)

u or

(]I

gt fl c _ 0 c ~

u E c middotshyco V

ltT

~

1fI 0

-= ~middotf0

i 0

c 5 o

E

OU c ~

_w ~~ ~ ~ cc~ 0

r-shy

0

u o

lt

u ~ V 3 (0 _o 0

~

~ Co)

a I)

~

~ ~ 0shy

co

~

j 2 rshy

1964 1970

EXPERIUENTAL HISTORY OF WEAK NEutRAL CURRENTS

HNt CII

NNC i FeWHC

~

aten 1960 101 11011101 ~ (oea 110( IISM I

1(- 1I0tllllq 1963 willi

Nucl Db1C1 DOuuet

10 ClIfICt In

I

Mony oretiCOI id to WNC 1larti~ In 131-~8 ~ ) y 11f1~i~~11 plaaa

all It- middotIfV Ihal I

ult aul first ora FCWNC

IG1M MtcftOflI1lll (1910)

1961 -61 GlasbOw--Sala IIIOCIII

HPWF~_IOI uaa iqacl MOICI I

Z bullbull Nri bull lIid ZI DIId flit

IUI moine by Ote73 -

nOtri--~I 111 oiClulI

ImOOfon 10 conllnu uareft fot II QUO syllm

Other conclusions A number of other fundamental questions were discussed in our previous report I)

their present status is

Violation of muon number conservation

(ve f v ll ) lt 1 Violation of leptonic conservation lt 6 (f~S = 0 1 nuctral current coupling 65 = 0 charged current coupling) lt 3

Neutrino flip intensi ty no neutrino flip intensity

] -- p + Ve ocrt = lt 1 10

I( -- p + v A boson has been postulated which prod uces tl

resonance of the type v ll + n -- lV -- p- + p If its properties are as predicted 10 11 ) its mass

is gt 55 GeV

Fig 3a Limit on Weak Neutral Currents from the CERN G rou p (published in P hys

Letts 1964)

Fig 2 Experimental hiltory or Weak NeunaJ Cutrents I)

Bet Experimental Limi t on

Neutral Current K Decay

The Search for vP-l and lIup-1TN

Upper LimitProcell _ - (CERN and 8NLJ Branching Couplin(C CODtant 011 the Reference

Ratio RatiO CC Ratio

1(+ - +e+e- lt 88 X 10-1 gV (e+e- )gv(e+ II) 7 X 10- 4 Cline et a l(~ middot 1

vJL --~ (-) H bull bull bull vp - v~ vJ P-un f(+-+p+p- lt 3 x 10- 5 gV (p+ p- )gV (p+ IIjJ ) 14 X 10- 2 Camerini et aLI-i-Oiscovery of

~ Vp +P - VJ 7T ~ n K+ - +vv lt 11 X 10- 4 gV (vv)gV (e+ v) 6 X 10- 2 Cline(81Before

V VtL

1 (WNC) or Slmllor 15 lt T lt 80~1tv +P - (J- - P7T r reactionDi~~ed ~ K~ - p+p- lt 16 x 10-8 gA(p+p-)gA(p+lljJ) i1 )( 10- 4 Bott shy~It OJ f3odenhausen

t t CERN el 31 K - p+p- lt 73 X 10- 5 gA(p+ p- )gA(p+ II) 16 x 10- 3 [Jottshy=~ f3od enhausenAfter WNC Oiscovereoa 02 eL al

K~ - op+p- No estimate gV (p+ p- )gV (p+ II ) no estimate

K~ - +e+e- No estimate gV (e+e- )gV(e+ v) no estimate 01

lins talk 01 FNAl K+ - + Oe+ eshy(Rzlt011 to 90 (L)] lt 8 x 10-8

no estimate C line(dl

J I (f~Revisea in -1970 (OCunoy et 01) + - +p+e- lt 3 X lO-5 violates Cl ine(dl 01 I lepton

conservation~7 70 ~ 80 f~ - pplusmnef lt 9 x lO-5 violatM [lotL shylepton Boden hausen

year conservation ct al

bull All estimates are 90 confidence limits

fig 3b CERN results (1967-1972) were well below the current and oblerved value of the Fig 43 The limits on Flavor Changing Weak Neutral Currrents from a [967 summary of Weak Neutral Current level after 1973-1974

D Cline

- 1-1

H I STORY OF THE SEARCH FOR K+- TT + tie ve shy

- Experimenlal LimitshyCline 2110- 4

Ixl0-4 Comeri ni et 01 BC

Utt t tt 57110- 5Lju nq et 01 BC

141 lOmiddotmiddotKltmS tt 01 o

94 I tomiddot 7Coblt t 017ro Vlaquotlaquotlaquo(t56 110middot bulla Wand Z moss (Cern) ~5 x10 10 ~laquolaquot( 14 I tomiddot Asa no e l 01 Q)at N

c

v c 1ft tt 85GeV025o

c

loJ- - M ~6GeV - LEP RESULTSCD L~~~~~~~~ __Mw z82GeV -shy

7l tOU w 82G~~ 0

_t ~10-10 2~ Mz92 GeV If)

+10 _ ~ Tho~ 020 E CXl

2 7 110~ Por ily violation +3 ~ E(SLAC EtlwrillltlItj10-92 New Koon facility

1960 t970 1980 1990

2eHISTORY OF THE VALUE OF SIN w DIRECT

Numoer or K~

in eloenmenl

11

0 35 811 ~ 2110 3

~ x10 5 7110

_value 01 sin28wwilh lime

18110 3 030 11110 3

0151 I I I I I I

73 75 77 7r n -- - shy 87 89

Year

Fig 4b Search for n - vii-direet Flavor Chansinl Weak Neutral Currents

Fig 5a The his tory of the value of sin1 elY

us 16

035 r-middot---- - --- ------ ----------

Various Modern Meosurements of si n 2

8 (M )w z

030r cu Q gtltu

0 olo~ Ii

E t 2 cu z 0 ~ ~cu olo

~ N

025rshy~ ~f =I - _1 I - bull bull1bull 1 _ r bull a a as a bull a --1-- ~- - shy

c If)

N

020I-0232500007 i I - - --- I -

1 01511___________________-

Q2 (momentum transferred in the NC process)

- INSERT A-

Fig 5b Insel1 A of Fig Sa

1I

- ---Experimental limi ts ---- shy

Loop Model UCU (1+N -fL~xl Effects with

6 Dbd(CESRl Level FCWNC

Dds ~-liJbull Retl1z lO- r [1 +1010 T+e+e-(1963-64l] (8deg8 Mixing 1

~ (UAll] [Dbd D bs 1710 shy

K-fLfl- ~ Dbs10-4 r ~-----~ Dbdt Dbs

Dbd

Ddsbull Uuc10-r

1111111111 II UcuFLWNC WZ

GIM WNCseonh I Ods

~ Discovery DiscoveryWt la-It shy

60 70 80 90 2000 year

Fig 630 History of the search for Flavor Changing Weak Neutral Currrents from the early 19608 to the preAent

lR

_1

HE RISE OF THE STANDARD MODEL ~ ~ _ o- _

- -- OF ELEMENTARY PARTICLES

~ --

A_-- -

- ~

~_ __ V J laquo

~ ~ ~ ~~ ~ ~ ~~ ~ ~ laquo~ cent~ ~

-J ltI

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~~

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u

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8 -fLP~ fL fLl L 9) r77777

lIdege+e - Std Mode ~

8 r fL __a

10-10 oJ11 v

shy TrVV ~ ~ laquo ~ ~

~

65 70 75 80 85 90 95

yeo r

Fi g 6b Search (or Flavor Champll~Dg Weak Neutral Current Decays Fig 7 The rise of the Standard ~ lodel

-49 20

Bet Experimental Limi t on

Neutral Current K Decay

The Search for vP-l and lIup-1TN

Upper LimitProcell _ - (CERN and 8NLJ Branching Couplin(C CODtant 011 the Reference

Ratio RatiO CC Ratio

1(+ - +e+e- lt 88 X 10-1 gV (e+e- )gv(e+ II) 7 X 10- 4 Cline et a l(~ middot 1

vJL --~ (-) H bull bull bull vp - v~ vJ P-un f(+-+p+p- lt 3 x 10- 5 gV (p+ p- )gV (p+ IIjJ ) 14 X 10- 2 Camerini et aLI-i-Oiscovery of

~ Vp +P - VJ 7T ~ n K+ - +vv lt 11 X 10- 4 gV (vv)gV (e+ v) 6 X 10- 2 Cline(81Before

V VtL

1 (WNC) or Slmllor 15 lt T lt 80~1tv +P - (J- - P7T r reactionDi~~ed ~ K~ - p+p- lt 16 x 10-8 gA(p+p-)gA(p+lljJ) i1 )( 10- 4 Bott shy~It OJ f3odenhausen

t t CERN el 31 K - p+p- lt 73 X 10- 5 gA(p+ p- )gA(p+ II) 16 x 10- 3 [Jottshy=~ f3od enhausenAfter WNC Oiscovereoa 02 eL al

K~ - op+p- No estimate gV (p+ p- )gV (p+ II ) no estimate

K~ - +e+e- No estimate gV (e+e- )gV(e+ v) no estimate 01

lins talk 01 FNAl K+ - + Oe+ eshy(Rzlt011 to 90 (L)] lt 8 x 10-8

no estimate C line(dl

J I (f~Revisea in -1970 (OCunoy et 01) + - +p+e- lt 3 X lO-5 violates Cl ine(dl 01 I lepton

conservation~7 70 ~ 80 f~ - pplusmnef lt 9 x lO-5 violatM [lotL shylepton Boden hausen

year conservation ct al

bull All estimates are 90 confidence limits

fig 3b CERN results (1967-1972) were well below the current and oblerved value of the Fig 43 The limits on Flavor Changing Weak Neutral Currrents from a [967 summary of Weak Neutral Current level after 1973-1974

D Cline

- 1-1

H I STORY OF THE SEARCH FOR K+- TT + tie ve shy

- Experimenlal LimitshyCline 2110- 4

Ixl0-4 Comeri ni et 01 BC

Utt t tt 57110- 5Lju nq et 01 BC

141 lOmiddotmiddotKltmS tt 01 o

94 I tomiddot 7Coblt t 017ro Vlaquotlaquotlaquo(t56 110middot bulla Wand Z moss (Cern) ~5 x10 10 ~laquolaquot( 14 I tomiddot Asa no e l 01 Q)at N

c

v c 1ft tt 85GeV025o

c

loJ- - M ~6GeV - LEP RESULTSCD L~~~~~~~~ __Mw z82GeV -shy

7l tOU w 82G~~ 0

_t ~10-10 2~ Mz92 GeV If)

+10 _ ~ Tho~ 020 E CXl

2 7 110~ Por ily violation +3 ~ E(SLAC EtlwrillltlItj10-92 New Koon facility

1960 t970 1980 1990

2eHISTORY OF THE VALUE OF SIN w DIRECT

Numoer or K~

in eloenmenl

11

0 35 811 ~ 2110 3

~ x10 5 7110

_value 01 sin28wwilh lime

18110 3 030 11110 3

0151 I I I I I I

73 75 77 7r n -- - shy 87 89

Year

Fig 4b Search for n - vii-direet Flavor Chansinl Weak Neutral Currents

Fig 5a The his tory of the value of sin1 elY

us 16

035 r-middot---- - --- ------ ----------

Various Modern Meosurements of si n 2

8 (M )w z

030r cu Q gtltu

0 olo~ Ii

E t 2 cu z 0 ~ ~cu olo

~ N

025rshy~ ~f =I - _1 I - bull bull1bull 1 _ r bull a a as a bull a --1-- ~- - shy

c If)

N

020I-0232500007 i I - - --- I -

1 01511___________________-

Q2 (momentum transferred in the NC process)

- INSERT A-

Fig 5b Insel1 A of Fig Sa

1I

- ---Experimental limi ts ---- shy

Loop Model UCU (1+N -fL~xl Effects with

6 Dbd(CESRl Level FCWNC

Dds ~-liJbull Retl1z lO- r [1 +1010 T+e+e-(1963-64l] (8deg8 Mixing 1

~ (UAll] [Dbd D bs 1710 shy

K-fLfl- ~ Dbs10-4 r ~-----~ Dbdt Dbs

Dbd

Ddsbull Uuc10-r

1111111111 II UcuFLWNC WZ

GIM WNCseonh I Ods

~ Discovery DiscoveryWt la-It shy

60 70 80 90 2000 year

Fig 630 History of the search for Flavor Changing Weak Neutral Currrents from the early 19608 to the preAent

lR

_1

HE RISE OF THE STANDARD MODEL ~ ~ _ o- _

- -- OF ELEMENTARY PARTICLES

~ --

A_-- -

- ~

~_ __ V J laquo

~ ~ ~ ~~ ~ ~ ~~ ~ ~ laquo~ cent~ ~

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~~

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u

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SEARCH FOR FCWNC DECAYS r--TI

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8 r fL __a

10-10 oJ11 v

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~

65 70 75 80 85 90 95

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Fi g 6b Search (or Flavor Champll~Dg Weak Neutral Current Decays Fig 7 The rise of the Standard ~ lodel

-49 20

H I STORY OF THE SEARCH FOR K+- TT + tie ve shy

- Experimenlal LimitshyCline 2110- 4

Ixl0-4 Comeri ni et 01 BC

Utt t tt 57110- 5Lju nq et 01 BC

141 lOmiddotmiddotKltmS tt 01 o

94 I tomiddot 7Coblt t 017ro Vlaquotlaquotlaquo(t56 110middot bulla Wand Z moss (Cern) ~5 x10 10 ~laquolaquot( 14 I tomiddot Asa no e l 01 Q)at N

c

v c 1ft tt 85GeV025o

c

loJ- - M ~6GeV - LEP RESULTSCD L~~~~~~~~ __Mw z82GeV -shy

7l tOU w 82G~~ 0

_t ~10-10 2~ Mz92 GeV If)

+10 _ ~ Tho~ 020 E CXl

2 7 110~ Por ily violation +3 ~ E(SLAC EtlwrillltlItj10-92 New Koon facility

1960 t970 1980 1990

2eHISTORY OF THE VALUE OF SIN w DIRECT

Numoer or K~

in eloenmenl

11

0 35 811 ~ 2110 3

~ x10 5 7110

_value 01 sin28wwilh lime

18110 3 030 11110 3

0151 I I I I I I

73 75 77 7r n -- - shy 87 89

Year

Fig 4b Search for n - vii-direet Flavor Chansinl Weak Neutral Currents

Fig 5a The his tory of the value of sin1 elY

us 16

035 r-middot---- - --- ------ ----------

Various Modern Meosurements of si n 2

8 (M )w z

030r cu Q gtltu

0 olo~ Ii

E t 2 cu z 0 ~ ~cu olo

~ N

025rshy~ ~f =I - _1 I - bull bull1bull 1 _ r bull a a as a bull a --1-- ~- - shy

c If)

N

020I-0232500007 i I - - --- I -

1 01511___________________-

Q2 (momentum transferred in the NC process)

- INSERT A-

Fig 5b Insel1 A of Fig Sa

1I

- ---Experimental limi ts ---- shy

Loop Model UCU (1+N -fL~xl Effects with

6 Dbd(CESRl Level FCWNC

Dds ~-liJbull Retl1z lO- r [1 +1010 T+e+e-(1963-64l] (8deg8 Mixing 1

~ (UAll] [Dbd D bs 1710 shy

K-fLfl- ~ Dbs10-4 r ~-----~ Dbdt Dbs

Dbd

Ddsbull Uuc10-r

1111111111 II UcuFLWNC WZ

GIM WNCseonh I Ods

~ Discovery DiscoveryWt la-It shy

60 70 80 90 2000 year

Fig 630 History of the search for Flavor Changing Weak Neutral Currrents from the early 19608 to the preAent

lR

_1

HE RISE OF THE STANDARD MODEL ~ ~ _ o- _

- -- OF ELEMENTARY PARTICLES

~ --

A_-- -

- ~

~_ __ V J laquo

~ ~ ~ ~~ ~ ~ ~~ ~ ~ laquo~ cent~ ~

-J ltI

~ E c 0 c

~~

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U - 0 CI J en C

u

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c ~I CD ~ C o 11 __ 0

0 0 = GI ~ gt-

- III

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I

8 - fLJL l (Cornett ) ~~r-middot middot 10-2

~-------~ -= i j _ bull o t _I(UA1) ---- - -

8 -fLP~ fL fLl L 9) r77777

lIdege+e - Std Mode ~

8 r fL __a

10-10 oJ11 v

shy TrVV ~ ~ laquo ~ ~

~

65 70 75 80 85 90 95

yeo r

Fi g 6b Search (or Flavor Champll~Dg Weak Neutral Current Decays Fig 7 The rise of the Standard ~ lodel

-49 20

035 r-middot---- - --- ------ ----------

Various Modern Meosurements of si n 2

8 (M )w z

030r cu Q gtltu

0 olo~ Ii

E t 2 cu z 0 ~ ~cu olo

~ N

025rshy~ ~f =I - _1 I - bull bull1bull 1 _ r bull a a as a bull a --1-- ~- - shy

c If)

N

020I-0232500007 i I - - --- I -

1 01511___________________-

Q2 (momentum transferred in the NC process)

- INSERT A-

Fig 5b Insel1 A of Fig Sa

1I

- ---Experimental limi ts ---- shy

Loop Model UCU (1+N -fL~xl Effects with

6 Dbd(CESRl Level FCWNC

Dds ~-liJbull Retl1z lO- r [1 +1010 T+e+e-(1963-64l] (8deg8 Mixing 1

~ (UAll] [Dbd D bs 1710 shy

K-fLfl- ~ Dbs10-4 r ~-----~ Dbdt Dbs

Dbd

Ddsbull Uuc10-r

1111111111 II UcuFLWNC WZ

GIM WNCseonh I Ods

~ Discovery DiscoveryWt la-It shy

60 70 80 90 2000 year

Fig 630 History of the search for Flavor Changing Weak Neutral Currrents from the early 19608 to the preAent

lR

_1

HE RISE OF THE STANDARD MODEL ~ ~ _ o- _

- -- OF ELEMENTARY PARTICLES

~ --

A_-- -

- ~

~_ __ V J laquo

~ ~ ~ ~~ ~ ~ ~~ ~ ~ laquo~ cent~ ~

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~ E c 0 c

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65 70 75 80 85 90 95

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Fi g 6b Search (or Flavor Champll~Dg Weak Neutral Current Decays Fig 7 The rise of the Standard ~ lodel

-49 20

_1

HE RISE OF THE STANDARD MODEL ~ ~ _ o- _

- -- OF ELEMENTARY PARTICLES

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65 70 75 80 85 90 95

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Fi g 6b Search (or Flavor Champll~Dg Weak Neutral Current Decays Fig 7 The rise of the Standard ~ lodel

-49 20