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CHAPTER1
Introduction
TheStandardModelofparticlephysicsisbuiltontopoftwocornerstones–twoquantumfield
theories:firstoneprovidingaunifiedapproachtotheweakandelectromagneticinteractions,the
seconddescribingthestrongandnuclearinteractions.ThelatteroftheseiscalledQuantumChromo-
Dynamics(QCD).Thefundamentalbricksofthehadronicmatterarequarksandthestrongforceis
mediatedbygluons.QCDdescribesthewayinwhichquarksandgluonsinteractwitheachotherto
createparticlesthatcouldbeobservedexperimentally,e.g.protons,neutronsandpions.Itexplains
alsohowthenucleonsformanatomicnucleus.QCDisaquantumfieldtheorywithavastnumberof
effectsandprocessesthatformacomplicateddynamicalpictureoftheinternalstructureofhadrons.
Amongothersitcomprises:confinement,asymptoticfreedom,approximatechiralsymmetry,axial
vectoranomaly,multipartoninteractions,highertwisteffects,saturation,andmanymore.With
sucharichenvironment,experimentalstudiesofQCDrequiremeasurementsofmanyobservables
atdifferentkinematicalregimestodistinguishamongvariouseffects.
TheLargeHadronCollider(LHC)allowstostudyQCDatenergiespreviouslyinaccessible.
DuringRun1,describedinthiswork,theseenergiesforproton–protoncollisionswerebetween0.9
and8TeV.Moreover,theCompactMuonSolenoid(CMS)experimentprovidesaverywidedetec-
torscoveragethatenablesparticlesdetectioninarangespanningfor∼20unitsinpseudorapidity.
Thereforeparticlesemittedatlowangleswithrespecttothebeampipecanbemeasured.Suchpar-
ticlesareproducedinanumberofQCDprocesses.Someoftheseprocessesaremediatedbyvacuum
quantumnumberexchangecalledpomeron.Thereforewithanaccesstotheforwardrapiditiessoft
andharddiffractiveprocessescanbeeffectivelystudied.Alsothelow-xpartondistributionfunc-
tionscanbeprobede.g.viaacrosssectionmeasurementfortheforwardjetsproduction.Moreover,
studyingcorrelationsbetweenproductionofobjectsatvariousrapidities,evolutionofQCD(inx
orQ2)canbeanalyzedandanaccesstoagluonsaturationregioncanbeobtained.Measurement
ofanactivityintheforwardregioncanalsobeusedtostudyunderlyingevent,especiallymultiple
partonscatteringandformationoftheprotonremnant.Finally,theforwardenergyflowandthe
forwardparticleproductioncanbeusedtotunehadronicmodelsofultra-highenergycosmicrays
interactionswithatmosphere.
Avastnumberoftopicsthatcanbestudiedwithobservablesdefinedbyanactivityatlarge
pseudorapiditiestriggeredacreationofadedicatedForWarDPhysicsAnalysisGroup(FWD
PAG)atCMS.Thispaperpresentsmainactivitiesandresultsobtainedwithinthegroupusingdata
recordedduringLHCRun1–datatakingperiodwhichstartedin2009andfinishedin2013.Author
ofthispaperwascloselyinvolvedinthedefinitionoftheFWDPAGphysicsprogramme.Hewas
involvedinthepreparationofthededicatedtriggers,simulationsofphysicsevents,definitionofthe
workflowincludingpreparationandtestsofthecomputinginfrastructure,studiesofthesensitivityof
theforwarddetectorsandeliminatingtechnicalproblems.Then,firstasaconveneroftheExclusive
