當前位置:文檔下載 > 所有分類 > Heavy Quark Production in $gammagamma$ Collisions
侵權投訴

Heavy Quark Production in $gammagamma$ Collisions

New results on inclusive heavy quark production in gamma gamma collisions are presented. Charm and bottom production are investigated at LEP II energies by the experiments ALEPH, DELPHI, L3, and OPAL. The total and differential cross sections for charm qua

Heavy Quark Production in $gammagamma$ Collisions

SI-2000-8August2000

HEAVYQUARKPRODUCTIONINγγCOLLISIONSA.BOHRER

¨FachbereichPhysik,Universit¨atSiegen,D-57068Siegen,Germany

E-mail:[email protected]

002Newresultsoninclusiveheavyquarkproductioninγγcollisionsarepresented.Charmandbottom productionareinvestigatedatLEPIIenergiesbytheexperimentsALEPH,DELPHI,L3,andOPAL.Thetotalanddi erentialcrosssectionsforcharmquarksaremeasured.Thecontributionsfromtheepdirectandsingle-resolvedprocessesareseparatedandtheirfractionsquanti ed.Moredetailedstudies,Ssuchasthedependenceofthecrosssectiononthetwo-photoncentre-of-massenergyandthecharm

structurefunctionF1γ,2c

,arereported.Theinclusivebottomcrosssectionispresented.Measurementsarecomparedtonext-to-leadingordercalculations.

1 ]

11Introduction

VevG 1Theproductionofheavy avourintwo-/ b2pphotoncollisionsisdominatedbytwopro- [

1*Dp

9cesses,thedirectandthesingle-resolvedpro-d/0cess.Bothcontributeinequalsharestoσd00heavy avour nalstatesatLEPIIener-/gies.Thelargequarkmassallowsreliablehpperturbativecalculationsforthedirectcon--tribution.Thesingle-resolvedoneinadditionpedependsonthegluondensityofthephoton.

Inthisarticlethenewmeasurements:hvfromtheLEPexperimentsonheavy avouriXproductionandthecomparisonwithnext-to-leadingordercalculations2aresummarized.rT

aOnlythemainresultsaregiven.Fordetailsthereaderisreferredtotheoriginalpapers.Figure1.Di erentialcrosssectiondσ/dpD TversusthetransversemomentumpD ToftheD +.

2

HeavyQuarkIdenti cation

3

Di erentialCharmCrossSection

Aclear,non-ambiguoussignalforcharm

quarkproductionisthepresenceofaD +.ThegooddetectorresolutionandwiththeThisgold-platedsignaturehasbeenexploitedlowkineticenergyavailable,theD +methodbyallfourLEPcollaborations.Boththeallowsforameasurementofthedi erentialproductionprobabilityP(c→D +)andthecrosssectionintransversemomentum(seebranchingratiotoD0π+aswellastheD0Figure1)andpseudorapidity.Thethreeex-branchingratiosarereasonablywell-known.

periments,ALEPH,L3,OPAL,agreeamongTheleptonicdecayhasbeenusedbythemselvesandwiththetheoreticalexpec-ALEPH(µ±forcharm)andL3(µ±ande±tation,thatthedistributioninpseudorapid-bothforcharmandbottom).Thoughtheseityisaboutconstant.Intransversemomen-analysesrelyonthemomentumspectrumastumthemasslessapproachfollowstheOPALtheoreticalinput,thestatisticsissubstan-measurements,whilethemassivecalculationtiallyincreased.

isclosertotheALEPHdata.

第1頁

免費下載Word文檔免費下載:Heavy Quark Production in $gammagamma$ Collisions

(下載1-3頁,共3頁)

我要評論

返回頂部
3d试机号每日的抉报