Treść książki
Przejdź do opcji czytnikaPrzejdź do nawigacjiPrzejdź do informacjiPrzejdź do stopki
8
ForwardPhysics–anewwindowonhighenergyinteractions
ProductionPhysicsGroup,andnextasaconveneroftheLow-xGroup(bothgroupsestablished
intheframesoftheFWDPAG)hewasresponsibleforleadingandcoordinationofanumberof
analysesbasedonobservablesmeasuredwiththeforwarddetectors.IntheExclusiveGrouphewas
closelyinvolvedintheexclusivediphotonanddielectronproductionanalysisandstartedsearchfor
exclusivelyproducedππpairs.Theseanalysesaredescribedinthescopeofthiswork.IntheLow-x
Group,authorwastheleaderoftheforwardenergyflow,forwardjetsandMueller–Naveletdijets
analyses.HehadalsoanimportantinputtothedijetK-factorandforward–centraljetsstudies.
Allofthemareincludedinthisoverview.Finally,during2013–2015periodhewasresponsiblefor
validationofthereconstructionofthedataandMonteCarlosamplesthatwereusedintheanalyses
presentedinthispaper.During2009–2011hewasworkingatCERNasaFellowandthenorganized
forwardphysicsgroupattheWarsawUniversity.
Accordingtotheauthor’sknowledge,thisworkisthefirstsuchextensivereviewofthefor-
wardphysicsresultsobtainedonthedatacollectedbytheCMSduringRun1intheproton–proton
collisions.ThereforethepapersummarizesandconcludesanentirechapteroftheCMSphysics
programme.Thepresentedresultswereofficiallyreleasedandpublishedduring2010–2016period.
Duringpreparationofthisoverview,someoftheanalysesstillawaitedforpublicationandwere
availableaspreliminaryCMSresults.Acommonaspectofalltheanalysesisausageoftheforward
detectorslocatedathighpseudorapiditiesclosetothebeamline.Anarrangementofthechapters
correspondstothelogicbehindthescientificprogrammeoftheFWDPAG.Startingfromthemea-
surementsoftheactivitycausedbyanunderlyingevent,thenmovingtothehardscaleobservables
(jets),selectingmorespecificdiffractiveeventswithapartofthedetectordevoidedfromanyparticles
activity,finallylookingateventswiththeexclusiveproduction,thatiswithnoadditionalactivity
exceptforthewell-definedfinalstate.Ineachchapterashortintroductiontothetheoreticaland
phenomenologicalproblemsisgiven,followedbyanoverviewoftheexperimentalresults.Authoris
awarethattherearemanyresultsontheforwardphysicsfromtheotherLHCexperiments.However
itwasdecidedthatthisworkshouldbededicatedexclusivelytotheresultsfromtheCMSexperi-
ment.Thereforenoeffortshavebeenmadetoincludeinthescopeofthisworktheoutcomeofthe
otherLHCexperiments.
InthesecondchapterofthispaperadescriptionoftheLHCoperationinRun1isgiven.Aspec-
ificationoftheCMSdetectorispresented.Anemphasisisputonsubdetectorsystemslocatedat
largepseudorapidities,closetothebeamlineandthusexposedtoalargeirradiation.Alsoatrigger-
ingsystem,dataacquisitionandasoftwareusedforanalysesaredescribed.Ashortsummaryofthe
performanceoftheCMSinRun1isalsoincludedandadetectorsystemevolutionduringthedata
takingperiodisoutlined.
ThethirdchapterisdedicatedtounderlyingeventstudiesperformedinthescopeoftheFWD
PAG.Underlyingeventisalltheactivitypresentinaneventnotdirectlyrelatedtothehardinterac-
tion(betterdefinitionofadivisionlinebetweenanunderlyingeventandahardinteractionisgiven
withinChapter3).Ameasurementofanunderlyingactivityisimportanttoapproachanumberof
QCDeffects,e.g.multiplepartoninteractions,rescatterings,protonremnantformation,finaland
initialstateradiation,hadronisationetc.Experimentaldataareusedasaninputtomodelsand
simulations.Theyenablebettertuningofgeneratorsandabetterunderstandingofsoftprocesses
presentineachevent.Moreover,studiesofanunderlyingeventareaprerequisitetoanalysesofhard
processesinwhichwell-definedobjects,e.g.jetsareproduced.Thesehardobjectsaremeasured
ontopofanactivityproducedinthedetectorbyunderlyingeventprocesses.Threeapproachesto
themeasurementsofanunderlyingeventatCMSarepresented.Theseare:measurementofthe
energyflowintheHadronicForwardcalorimeter,measurementoftheenergyflowintheCASTOR
calorimeterandmeasurementofthechargedtracksmultiplicityineventswithahigh-pTleading
object.Differentobservablesandvarioussamplesofeventsincludedintheanalysesprovideanop-
portunitytomakeadistinctionbetweenmiscellaneouseffectsandasaresulttobettertuneMonte
Carlogenerators.
