Fluxes of atmospheric muons underwater depending on the smal(2)

(E)

π,K

(E) / φ

D,Λc

φ

10

10

10

10

Eµ , GeV

Figure2.Ratioofthedi erentialpromptmuonspectrumatsealeveltotheconventionalone.

. pm

Ã

L '

F

FRV q K NP Z H

5430

,

5 ,

m

PS

(m *H9

**9 0567 l

**9 0567 l 356 &7(4 0 l

Figure3.Promptmuoncontributionath=4kmw.e.vs.Eµ.

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater i

( K q

m

K,p

( K q ,

m

l l (m ! 7H9

m

L '

F

5 ,

m

PS

FRVq

NP Z H

NP

Figure4.Ratioofthepromptmuon uxunderwatertotheconventionaloneasafunctionofcosθatEµ≥100TeV.

depthof4kmofthewaterequivalent(w.e.)andforcosθ=0.2.Asisseenfromthis gure,Rpmrelatedtothegluondensityslopeλ=0.5isafactor3greaterthanthatforλ=0.1atEµ 10TeV.

Zenith-angledistributionsofthepromptmuoncontributionatdepths1-4kmw.e.,calculatedforEµ>100TeV,areshownin gure4.HereweusedpredictionsoftheGGVmodelfortwovaluesofthegluondensityexponent,λ=0.1(dash)andλ=0.5(solid).Asonecanseein gure4,Rpmincreasesfortheverticaldirectionfromabout0.2atthedepthoftheBaikalNT(1.15km)[12]toabout0.5attheNESTORdepth(～4km)[13].Forthelargerzenithangles,θ～75 ,thiscontributionbecomesapparentlysizableatdepths3 4km.Di erencesinthepredictionsowingtoachangeofλ,from0.1to0.5(seeh=2and3kmw.e.),arealsoclearlyvisible:theratioRpm(λ=0.5)/Rpm(λ=0.1)ath=2kmw.e.growsfromabout1.5toabout5ascosθchangesfrom1to0.2.

Herewesupposednodi erencesbetweenPRSandGGVcalculationsapartfromthoserelatedtothecharmproductioncrosssections.Actuallyoneneedstocomparetheprimaryspectrumandcomposition,nucleonandmesonproductioncrosssectionsandotherdetailsoftheatmosphericnuclearcascadebeingusedinabovecomputations.Thesesourcesofuncertaintieswouldbeconsideredelsewhere.

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater i

5.Summary

Inordertotestthesmall-xgluondistributione ectwehavecomputeddeep-seapromptmuon uxesusingpredictionsofcharmproductionmodelsbasedonNLOcalculationsofthePQCD[2]-[4].ThepossibilitytodiscriminatethePQCDmodels,di eringintheslopeofthegluondistribution,seemstobeachievableinmeasurementsoftheunderwatermuon uxatenergies50-100TeV.

Hardlyappearedatsealevelforenergiesupto105GeV( gures1,2),adependenceonthespectralindexλofthesmall-xgluondistributionbecomesmoredistinctatdepths3 4kmw.e.( gures3,4).Atthedepthof4kmandattheangleof～78 onecouldobservethePM uxtobeequal,forλ=0.5,totheconventionaloneevenformuonenergy～10TeV(thecrossoverenergy).Whileforλ=0.1thecrossoverenergyisabout70TeV.Forthehighenergythreshold,Eµ>100TeV,andath 3kmw.e.,theratioRpmisnearlyisotropicupto～60 .The“crossoverzenithangle”atagivendepth,θc(h),dependsapparentlyonthesmall-xexponentλofthegluondensityinsidecollidingnucleons:

cosθc|λ=0.5 0.3andcosθc|λ=0.1 0.1forh=3kmw.e.

References

[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]

LearnedJGandMannheimK2000Ann.Rev.Nucl.Part.Sci.50,679.PasqualiL,RenoMHandSarcevicI1999Phys.Rev.D59,034020.GelminiG,GondoloPandVarieschiG2000Phys.Rev.D61,056011.GelminiG,GondoloPandVarieschiG2001Phys.Rev.D63,036006.MartinAD,StirlingWJandRobertsRG1993Phys.Rev.D47,867.

LaiHLetal.1995Phys.Rev.D51,4763;LaiHLetal.1997Phys.Rev.D55,1280.MisakiA.etal1999Proc.26ICRC(SaltLakeCity)vol2,p139,hep-ph/9905399.NaumovVA,SinegovskayaTSandSinegovskySI2000Phys.Atom.Nucl.63,1923.SinegovskayaTSandSinegovskySI2001Phys.Rev.D63,096004.AndresEetal.(AMANDACollaboration)2000Astropart.Phys.13,1.AmramPetal.(ANTARESCollaboration)2000Astropart.Phys.13,127.BelolaptikovIAetal.(BaikalCollaboration)1997Astropart.Phys.7,263.

AnassontzisEGetal.(NESTORCollaboration)2000Nucl.Phys.B(Proc.Suppl.)85,153.AnderssonB(SmallxCollaboration)2002Smallxphenomenology:Summaryandstatus,hep-ph/0204115.

BallRDandLandsho PV2000J.Phys.G:Nucl.Part.Phys.26,672.KaidalovAB2001ReggepolesinQCD,hep-ph/0103011.SchleperP2001Softhadronicinteractions,hep-ex/0102051.VogtR2000Prog.Part.Nucl.Phys.45,S105.

YoshidaR(onbehalfofZEUSandH1Collaboration)2001HERAsmall-xand/ordi raction,hep-ph/0102262.

MartinAD,RobertsRG,StirlingWJandTorneRS1999Nucl.Phys.B(Proc.Suppl.)79,iHLetal2000Eur.Phys.J.C12,375.

KuraevEA,LipatovLNandFadinVS1976Zh.Eksp.Teor.Fiz.71,840;KuraevEA,LipatovLNandFadinVS1977Zh.Eksp.Teor.Fiz.72,377;BalitskyIIandLipatovLN1978Yad.Fiz.Yad.Fiz.28,1597.BrodskySJetal1999JETPLett.70,155,hep-ph/9901229;

[23]

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater i

Fluxesofatmosphericmuonsunderwater9

[24][25][26][27][28][29][30][31][32][33][34][35][36]

KimVT,LipatovLNandPivovarovGB1999TheNext-to-LeadingdynamicsoftheBFKLPomeron,hep-ph/9911242.

KhalchukovFFetal1985Proc.19ICRC(LaJolla)vol8,p12.BakatanovVNetal.1992Yad.Fiz.55,2107.

ZatsepinGTetal.Bull.oftheRussianAcad.ofSci.Ser.Phys.199458,2050.RhodeW1994Nucl.Phys.B(Proc. …… 此处隐藏：3843字，全部文档内容请下载后查看。喜欢就下载吧 ……