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1、Quenchingofresonanceproductioninheavy-ioncollisionsat1÷2AGeV∗A.B.Larionov†,W.Cassing,S.Leupold,U.MoselInstitutf¨urTheoretischePhysik,Universit¨atGiessen,D-35392Giessen,GermanyAbstractWestudythepionproductioninheavy-ioncollisionsatSISenergieswithinthecoupled
2、resonanceBUUmodel.ThestandardcalculationoverpredictsthepionmultiplicityinthecentralAu+Aucollisionat1AGeVbyaboutafactorof2,whichisinterpretedasasignatureforthequenchingoftheresonanceproduction/absorptioninnucleon-nucleoncollisionsathighnucleardensity.Results
3、ofthecalculationstakingintoaccountaspecificformofquenchingarepresentedforpionspectrafromlightandheavysystemsaswellasforthepionin-planeandout-of-planeflow.I.INTRODUCTIONarXiv:nucl-th/0103019v222Jun2001Modificationsofhadronsindensenuclearmatterarecurrentlyinthec
4、enteroftheoreticalstudies[1,2].Inparticular,themultiplepionproductioninheavy-ioncollisionsoffersaninterestingpossibilitytolookatthepropertiesofthebaryonresonancesinnuclearmatter[3–11].Itiswellestablished(c.f.[3,4])thatatbeamenergiesof1÷2AGeVpionsareproducedm
5、ostlyinthetwo-stepprocessNN→NR,R→Nπ,whereRstandsforthe∆(1232)orhigherbaryonresonances.However,thereisanoveralltendencyoftransport∗SupportedbyGSIDarmstadt†OnleavefromRRC”I.V.KurchatovInstitute”,123182Moscow,Russia1modelsexplicitlypropagatingresonancestooverp
6、redictthepionmultiplicityinheavy-ioncollisionsatthebeamenergy∼1AGeV(c.f.[12]).Furthermore,takingintoaccountin-mediumpiondispersionrelationsevenincreasesthepionyield[13–15].Inthepresentworkwestudytheeffectofpossiblein-mediummodificationsofthereac-tionratesNN↔N
7、R(1)onpionproduction.Adescriptionoftheexperimentaldataonthepionmultiplicitiesre-quiresanin-mediumreductionoftherates(1).Wepropose,therefore,adensity-dependentmodificationofthetransitionrates(1),whichgivesareasonabledescriptionofthepionmultiplicitiesinthesyst
8、emsC+C,Ni+NiandAu+Auatthebeamenergyof1÷2AGeV.Wewillshow,moreover,thatthismodificationisconsistentwithotherpionobservables,i.e.transversemassandkineticenergyspectra,angulardistributionsandin-planecollect
