Summary Talk: Experimental High Energy Physis
J.C. Anjos
CentroBrasileirode PesqusasFsias
RuaDr. XavierSigaud150,RiodeJaneiro,22290-180, RJ,Brasil
e-mail: janjosbpf.br
Reeivedon25April,2001
AsummaryoftheontributionsonExperimentalHighEnergyPhysisattheXXIBrazilianNational
Meeting onPartile and Fieldsis presented. There were atotal of 28ontributions, 21inPanel
Sessions and7inOralSessions.
1 Introdution
The main impression left in the Sessions dediated
to Experimental High Energy Physis is that there
is presently a lot of ativity of Brazilian groups in
tendierentexperiments. A qualitativehangein the
partiipation of the Brazilian groups working in
In-ternational Collaborations was also observed. In the
eightiesmostofthepartiipationwasinDataAnalysis
and manpowerfor mounting the experiments. In the
late ninetiesweobservea growing leadershipin
hard-ware projets for detetors and front-end eletronis.
Wepresentbelowthelistoftheexperimentsforwhih
therewereontributionsatthismeeting:
Researh and Development (R&D) Projets
in 4experiments:
ATLAS(Cern) -HiggsandBeyond...
LHCb(Cern)-CPviolationintheBsystem.
AUGER OBSERVATORY (Argentine) - Extreme
energiesosmirays.
EASCAMP(Campinas)-Extensiveairshowers.
PhysisAnalysisResultsfrom4experiments:
E791(Fermilab)-CharmHadroprodution.
FOCUS(Fermilab)-CharmPhotoprodution.
D0(Fermilab)-ppollisionsat1.8 TeV.
DELPHI (Cern) - e +
e ollisions at the Z massand
beyond.
Interestingexperimentalprojetspresentedinother
SessionsoftheMeeting:
GRAVITON Projet (S~ao Paulo) - Detetion of
gravitationalwaves[1℄.
ATHENA's Projet (Cern) -Produtionand study
ofantihydrogen[2℄.
butions for eah experiment and the referene to the
abstrat in theProgramof theMeeting,to these
Pro-eedingsorto alreadypublished papers. Experiment
ATLAS:
Five ommuniations at the meeting. Main
a-tivities onentrated in alorimetry. A group from
COPPE/UFRJhasdevelopedfront-endeletronisfor
the read-out of the tile alorimeter. The system will
sum the signalsfrom dierent ellsof the alorimeter
for triggervalidation ofevents. A prototypewasbuilt
in Brazilandis beingtestedforfutureprodution[3℄.
The COPPE group has also developed a software
algorithm basedonneuralnetworksfordisrimination
between eletronsand jetsfor theseond leveltrigger
forATLAS[4℄.
Alternative algorithms for disriminating between
eletronsandjetsusingatopologimappingofthe
en-ergy deposition in the alorimeter were alsopresented
[5℄,[6℄.
Experiment LHCb: Intense ativity from UFRJ
group: four presentations, two on hardware projets,
one on muon trigger simulation and one on the
esti-mate of signal level for the rare deay B 0
s
!
+
.
1) Performaneof WirePad Chambers:
PrototypesofwirePadhambersthat will beused
inthemuonsystemforLHCbweretestedbytheUFRJ
groupwithminimumionizingpartilesandtheresults
werepresented[7℄. Part of thehamberswill be built
in BrazilbytheUFRJgroup.
2) The CARIOCA hip:
Prototypeofintegrated iruithasbeendeveloped
ChambersoftheLHCbmuonsystem[8℄.
3) Software Development:
Detetor ineÆienies, dead time, noise and ross
talk eets were inluded in the digitalizationmodule
of theLHCbsimulationprogram[9℄.
4) Study ofthe LHCbsensitivity tothe rare
deay B 0
s !
+
.
SimulationstudyofUFRJgroupshowsthatpresent
design of the detetor appears to be suitable for the
learobservationofthisraredeay[10℄.
Experiment AUGER: A detailed artile about the
Auger Projet is inluded elsewere in these
Proeed-ings[11℄. During2001therststageoftheprojet,the
EngineeringArray,overinganareaof54km2,willbe
ompletedinMalargue,Argentina,siteoftheSouthern
HemisphereObservatory.
Thestatusoftheprojetwaspresented. TheAuger
ProgressReport of February2001indiates that 21of
the40Cerenkovtanksofthearrayarealreadydeployed
and theeletronis ofthetanks arebeingmounted. A
majorbreakthroughwasahieved: forthersttimethe
Central Data Aquisition System has ommuniated
with surfaedetetor stationsin the observatory site.
ThesatelliteinternetonnetionfromMalargueisnow
operational. Therst monitoringdatafrom thetanks
arealreadyin theAugerWebServer.
FortheEngineeringArraythegrounddetetorswill
beoverlookedby twouoresenedetetor telesopes.
FollowingtheProgressReport,theLosLeones
uores-enedetetorbuildingisreadyandthemirrorsupport
struture for the uoresene telesope is already in
plae. The rstoptiallterwasshipped to Malargue
andtherstfullamerahasbeensuessfullytestedin
Romeandwillsoonbeheadedforthesite.
The Rio group (CBPF/PUC/UFF) is responsible
fortheinstallationofthesurfaedetetorsandforthe
simulation and reonstrution software [12℄,[13℄,[14℄.
An engineerisalsoinvolvedwiththeCentralData
A-quisitionSystem(CDAS)projet.
TheCampinasgroup(UNICAMP)isresponsiblefor
manufaturingandforshippingtheCerenkovtanksto
Malargue and for thedesign and onstrution of part
of theuoresenedetetors: diaphragm,shuttersand
orretion lenses. Thegroupis also involvedwith the
simulation of extensive air showers using the
genera-tion ode CORSIKA and using dierent models for
the hadroni interations simulated by SIBYLL and
QGSJET [15℄.
Experiment EASCAMP: Data obtained during
the period 1998-2000with the entral muon detetor
of EASCAMP (Campinas) was presented. [16℄.The
StreamerTubes,theiroperationmodeanddata
aquisi-andstabilityofthestreamerhambersduringthedata
aquisition period was shown. The zenithal
distribu-tion of muons obtained from the data was presented
and ompared with other experiments, like EASTOP
(GranSasso,Italy).
ExperimentE791: Finalresultsfrom4analyses
per-formed reently by the CBPF group were presented.
Althoughrepresentingabout10%ofthenumberof
ol-laborators,theCBPFgroupwasresponsibleforabout
20%ofthepubliationsofthisexperiment.
1)AmplitudeanalysisofthedeaysoftheD +
and D +
s
in 3pions:
A Dalitz Plotanalysis was done with asample of
117261D +
and84844D +
s .
Theamplitudeanalysishasshownadominant
on-tribution of salar resonanes. It was possible to
measurewith verygoodpreisionthe massandwidth
ofseverallightresonanes.Forthersttimealear
signalofthesalarmeson(500)withmass478249
MeV and width 324417 MeV was observed [17℄.
2) Partile-antipartile prodution
asymme-triesfor
,, and baryons:
Partile-antipartileasymmetriesweremeasuredas
funtionsof Feynman x
F
(saledlongitudinal
momen-tum) and transverse momentum p 2
T
in the ranges
0:12 < x
F
< 0:12 and 0 < p 2
T
< 4 for the
hy-perons and 0:1 < x
F
< 0:6 and 0 < p 2
T
< 8 for
the
. No asymmetry is predited by perturbative
QCD. Measured asymmetry is then a onsequene of
the hadronization proess, espeially leading partile
eets.
Substantial asymmetries were found for hyperons
evenatx
F
=0. Leadingpartileeets observedin
hy-peronprodutionareinqualitativeagreementwith
the-oretialpreditions[18℄.
Forthe
a onstant asymmetry of 12% was
ob-served[19℄.
ExperimentFOCUS:1)Photoprodution
asym-metriesofthe harm baryons
,
++
and 0
:
As in hadroprodution no asymmetry is expeted
in perturbative QCD. The measurementof
photopro-dutionasymmetriesforthese baryonsouldthen
pro-videvaluableinformationonthehadronizationproess,
whih is one of the least understood phenomena in
QCD.
Preliminaryresultsontheharm-antiharm
photo-prodution asymmetry using +
=
,
++
=
and
0
=
0
were presented[20℄. Theasymmetrywas
stud-ied in intervals of p 2
T , p
L
, and x
F
for the ase of
baryons,whileglobal valueswere extratedfor the
As in hadroprodution, a onstant asymmetry of
12%forthe
wasobserved. Verypreliminary results
indiate a higher asymmetry, of the order of19%, for
the
baryons.
2) Preliminary
branhing ratio
measure-mentsfrom FOCUS.
Thelarge harmsampleolletedbyFOCUS,over
onemillionfullyreonstrutedharmevents,allowhigh
preision measurements of harm partile properties.
InpartiularFOCUShasreonstrutedover20,000
baryons,theworldlargestsample.
The branhing ratios of the deay modes
!
and
! p
K 0
relativeto the dominant deay
hannel
!pK were presented [21℄. The
prelimi-naryresults are in agreement, within errors, with the
valuesreportedbythePartileDataGroup. Thestudy
ofsistematierrorsandthebranhingratioof11other
deaymodesarein progress.
Experiment D0: Dirative Physis will be one of
the topis investigated by the experiment D0 in the
next ollider run, starting in April 2001. To
aom-plish this goal the Brazilian group has proposed the
onstrution of a new sub-system to be inorporated
in the D0 spetrometer: the Forward Proton
Dete-tor. The Roman Pots, insertion devies in the beam
line to house the new detetors, were built at the
LNLS in Campinasandthe detetordesignand
simu-lationisundertheresponsibilityoftheBraziliangroup
(CBPF/UERJ/UFRJ/UFBa/IFT/LNLS).
1) Studies of the eet of multiple
intera-tionson the dirative eventsat D0.
The ourreneof multiple interationsin the same
beamrossingwassimulatedanditseetontriggering
dirative events wasstudied [22℄. Time information
provided by the luminosity monitors and the event
multipliitywereused forhelpingeÆientlytriggeron
difrativeproesses.
2) Study ofHard Diration atD0.
Hard diration resultsfrom thelast D0 run were
presented. Measurementofrates,rapiditygaps,
trans-verseenergyandenergydependenewerepresentedand
omparedwith preditionsof severalmodels [23℄. The
gapfrationofdirativedijet eventsrelativetoall
di-jetswaspresentedforforwardjets(0.65%0.04%)and
forentraljets(0.22%+0.05%-0.04%)at 1.8TeV.
Experiment DELPHI: The CERN Large Eletron
Collider -LEPwasshutdownin November2000,after
12yearsofintensestudyofe +
e ollisionsintheenergy
range91-209GeV.Verypreisetests oftheStandard
Modelwereperformed. Atthemeetingseveralanalyses
and UERJ searhing for new physis were presented,
as well as a talk on the searh for the Higgs boson:
1) Higgs searhes atLEP-II:
Thiswasoneofthemostawaitedtalksofthe
meet-ingsineatthehighestenergiesofLEP-IIafewevents
werefoundompatible with Higgsbosonsprodued in
the proess e +
e ! Z
! Z 0
H 0
. A detailed artile
abouttheHiggssearhatLEP-IIisinludedelsewerein
these Proeedings[24℄. TheHiggssearhwasdone by
thefourLEPexperimentsandafterapplyingverytight
utstoreduethebakgroud3eventsfromALEPHand
onefromL3survivedasHiggsandidates. Inthe
om-bined data from the 4 LEP experiments an exess of
events for Higgs masses near 114 GeV was observed,
2.9 away from the expeted bakground. Although
not enoughto onrm theHiggs disovery, this result
allows one to set a limit for the Higgs mass at 95%
Condene Levelatm
H
>113.2GeV/ 2
.
2) Searh for staus:
Dataolletedintheenergyrange192to202GeV
wereanalysedlookingfor thestaus,the
supersymmet-ri partner of the taus in the ontext of the Minimal
Supersymmetri Standard Model. The preliminary
re-sults obtainedbythe UFRJgroupshowanagreement
withstandardmodelspetations[25℄.
3) Searh for four harged leptons nal
states:
The six nal states of harged four-leptons
pro-dued in e +
e ollisionsin theenergyrange184-202
GeV were analysed. Deviations from the Standard
Model ross-setion preditions would be a signal for
newphysis. Thetotalross-setionwerealulatedin
ablind analysis and ompared withtheones expeted
from simulations. Good agreement was found [26℄.
4) Searh forspontaneous R-parity violation
at LEP-II:
In the supersymmetri extensions of the Standard
Model the disrete symmetry alled R-parity plays a
determinantrolein thephenomenologyof themodels.
In the ase when this symmetry is not onserved the
singleprodutionofsupersymmetri partilesantake
plae. Searhes forspontaneus R-parity violating
sig-nals at LEP2 were performed under the assumption
of R-parity violation in the third lepton family. The
expeted topologyforthe deayofapair ofharginos
into two aoplanar taus plus missing energy showed
Referenes
[1℄ APrimeiraFasedoProjetoGraviton:oDetetorde
On-dasGravitaionaisMarioShenberg-OdylioD.Aguiar
etal-oralpresentation.
[2℄ Low energy (anti)atoms for preision tests of basi
Physis - D. M. Silveira, O. Pereira, M. Veloso and
ClaudioL.Cesar-Braz.J.Phys.,thisissue,(2001).
[3℄ OSistemaSomadorparaFormaroSinaldeTriggerdo
CalormetroHadr^oniodoATLAS-AugustoSantiago
Cerqueira,JoseManoeldeSeixas,LuizPereiraCal^oba,
FelipeSoares C.Rodrigues,Bruno deCarvalhoCosta
andRiardoRezendeRamos-panelpresentation.
[4℄ MapeamentoemAneis paraumaSepara~aoNeuronal
Eletron-Jato usando Calor
imetros Multi-amadas e
Multi-segmentados-AndreRabellodosAnjosandJose
ManoeldeSeixas-panelpresentation.
[5℄ Um Mapeamento Topologio para um Disriminador
NeuronaldePartulasBaseadoemCalormetros
Seg-mentados-MarosdaRohaVassaliandJoseManoel
deSeixas-oralpresentation.
[6℄ Novos Algoritmos Baseados na Transformada de
HoughparaaDete~aodeTraosnumDetetorde
Fi-bras
OtiasCintilantes-AugustoCesarHeluyDantas,
JoseManoeldeSeixas andPabloTupinambaCampos
-panelpresentation.
[7℄ PerformaneofWirePadChambersfortheMuon
Sys-temoftheLHCbExperiment-BernardM.Marehal,
DanielleMagalh~aesMoraes,
EriaPolyarpo,Leandro
SalazardePaulaandMiriam Gandelman-panel
pre-sentation.
[8℄ Fast binary Front-End implemented in a 0.25m
CMOS tehnology using a novel urrent-mode
teh-nique -Danielle Magalh~aes Moraes, F.Anghinol, P.
Jarron,A.RivettiandP.Devall-panelpresentation.
[9℄ SimulationofthedigitizationintheLHCbmontearlo
program and study of its inuene on the L0 muon
trigger performane -S.Amato, P. Colrain, J. R. T.
de Mello Neto, M. Gandelman, J. H. Lopes - panel
presentation.
[10℄ StudyoftheLHCbsensitivitytotheraredeayB 0
s !
+
- Bernard M. Marehal,
Eria Polyarpo and
MiriamGandelman-panelpresentation.
[11℄ CosmiAelerators andTerrestrialDetetors-R.C.
Shellard-Braz. J.Phys.,thisissue, (2001).
[12℄ Simula~aodasontribui~oesdevidasaLuzCerenkovea
Atenua~aoAtmosferianosDetetoresdeFluores^enia
do Observatorio Pierre Auger -Maria Gonalves do
Amaral-panelpresentation.
[13℄ Estudo daEi^enia dosDetetores deFluores^enia
doObservatorioPierreAugernaReonstru~aoda
En-fun~aodeumtetodenuvensdealturavariavel-Danays
Morejon Gonzalez, Ronald C. Shellard and Maria
GonalvesdoAmaral-panelpresentation.
[14℄ Reonstru~ao Geometria de Raios Cosmios
Alta-menteEnergetiosnoObservatorioPierreAuger-
Jo-hanaChirinosDazandRonaldCintraShellard-panel
presentation.
[15℄ Carateriza~aodeChuveirosAtmosferios-Fernando
Catalaniand JoseAugusto Chinellato-panel
presen-tation.
[16℄ Muons Observados om o Detetor Central do
EAS-CAMP-AndersonCamposFauthandSilviaPaganini
-panelpresentation.
[17℄ ResultadosFinaisdaAnalisedeAmplitudesdosCanais
D +
e D
s
! 3 om dados do Experimento E791
(FERMILAB) - I. Bediaga, A. Massaerri, J. M. de
MirandaandA.Reis-panelpresentation.
[18℄ StudiesintheProdutionofBaryonsin500GeV/
NuleonInterations-JavierSolanoandJ.C.Anjos
-panelpresentation.
[19℄ +
asymetriesin500GeV/ N interations
-J.C.Anjos,J.Magnin,F.R.A.Sim~aoandJ.Solano
-panelpresentation.
[20℄ PhotoprodutionAsymetriesoftheCharmBaryons,
++
and o
atFERMILABExperimentE831/FOCUS
- Jo~ao dos Anjos, Ceilia Uribe Estrada, Alberto
Sanhes Hernandez and Marleigh Shea -panel
pre-sentation.
[21℄ Preliminary Branhing Ratio Measurements from
FOCUS - Jo~ao C. dos Anjos and Eleazar Cuautle
-panelpresentation.
[22℄ Studies of the Eet of Multiple Interations on the
Dirative Events at the D0 Detetor - Wagner de
Paula Carvalho and Andre Sznajder - panel
presen-tation.
[23℄ HardDirationatD0-GilvanA.Alves-oral
presen-tation.
[24℄ Searhes atLEP2-MariaBegalli-Braz. J. Phys.,
thisissue,(2001).
[25℄ Update on the searh for stausin the ontext of the
MSSMwithintheDELPHIollaboration-Sandra
Am-ato,MiriamGandelman,JoseHelderLopesandMikael
Berggren-panelpresentation.
[26℄ Chargedfour-leptonsProdutionatLEP2Energiesin
DELPHI-MariaBegalli,LuizMartinsMundimFilho
andMaraElenaPol-oralpresentation.
[27℄ Searh for Spontaneous R -parity violation at LEP2
-DanielleMagalh~aesMoraes,LeandroSalazardePaula
