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long-lived exotic particle を含む SUSYの探索. 陣内 修 (KEK) 研究会「 LHC が切り拓く新しい素粒子物理学」 2008 年 3 月 28-29 日. イントロダクション. 長(超?)寿命粒子は数多くのSUSYモデルに登場する この様な粒子の発見は、いくつもの重要な素粒子問題に対しての解もしくはヒントを与える 暗黒物質問題、階層問題 、 Extra dimension flavor question, charge quantization, etc その存在、 property が与える物理的インパクトは重要、そこでまず - PowerPoint PPT Presentation
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long-lived exotic particle (KEK)
LHC 2008328-29
Extra dimensionflavor question, charge quantization, etc
property March 29, 2008*
for 3 cases { }March 29, 2008*
GMSBNLSP LSPtNon-pointing
, kink
AMSB chargino (: kink)
Split-SUSY, glavitino LSP(R-hardon)
March 29, 2008*Phys.Rept,438 (2007)1.
March 29, 2008*1 (w.r.t. 2 (Electric? color? magnetic?) SUSYnon RPV N2 1) cascade decay products(SUSY) 2) direct production (R-hadron)
Geant4full(A) Sleptons, R-hadrons ()
Ionization energy loss (R-hadron case) muon (TOF)
(B) chargino (or slepton)
(C) neutralino (non-pointing ) mSugra likekink ordisappearingtrackheavy slow particlesnon-pointingphotons(A)(C)(B)
ATLAS full simulationSUSYpackageATLASsimulation1(1) slepton, gaugino single particle gun, interfaceEvent Generation(2) R-hadrons R-hadron interactiondE/dx, interaction cross sectioncharge flippingMarch 29, 2008*
March 29, 2008*
(A.1) ATLASMarch 29, 2008* (Slepton, chargino, R-hadron)Ionization loss Bethe-Bloch (b~1/b2, b~1MIP)
(R-hadron)
gluino,stop p/r/K/p/n deposit = ~1GeV x 10-15 (~12,gluino R-hadron)
high-pT muonmuonTOF(b)2nd RPC(Barrel)3.125ns, MDT(Barrel + EndCap) ~0.7nsMuon recon.b=1muont0drift tubetrackc2 t0optimizeb bmuon
March 29, 2008*(A.1) ATLAS(Muon)
(A.1) ATLAS() March 29, 2008*b~1TOFmuon
TRT (transition radiation tracker) 73(36/track) low threshold: -- Ionization loss trackhigh threshold: -- TR /e low-Pt (lowb)Ionization HTHigt-Pt muonsno TR HT
56cm107cmR-hadronsleptonh=1.0
(A.1) ATLASbmuon (bethe-bloch)(R-hadron)
b
event display gluino R-hadronMarch 29, 2008*High-pT track1muonback-to-backsleptonmuonreconstruct
(A.2) ATLASTOF LHC BC (=25ns) [ LEP(25ms), Tevatron(396ns), HERA(96ns) ]b > 0.5 March 29, 2008*Atlas level-1 muon trigger systemRPC (Barrel subsystem) and TGC (Endcap subsystem) 25nsSeverer constraint for EndCapRPC r = 6.8, 7.5 and 10mTGC z = 12.9, 14, 14.5m
(A.2) SleptonCascadeobject100GeV slepton NLSP (GMSB L=30TeV, Mm=250TeV)
R-hadron
55%40%R-gluino (R-stop)mu6 menu (muon pT>6GeV) b0.6charge flippingR-gluinoEvent Filter(LvL3 trigger)
March 29, 2008*
Level-2 trigReconstructionR-gluino20-30%10-15%300GeV-2TeVR-stop20-30%20-30%
menuEfficiencymu40muon pT>40GeV95%xe200missing ET>200GeV63%em25iIsolated EM cluster E>25GeV46%
March 29, 2008*muoninclusive muonsLVL2 RPC TOF(3.1ns)b(=v/c) LVL2 (b, pT, h)sleptonmuonearly dataL2 mass [GeV](A.2) sleptonpT>40GeV, b40GeV< 0.2Hz at 1033cm-2s-1inclusive muonGMSB slepton (m=100GeV)500pb-1
(A.3) R-hadron jet (pT>100GeV)dR250GeV)
(1) 1hard muon(ID)(2) back-to-backID-trackTRTHT/LT
March 29, 2008*
(B.1) kink, AMSBcharginoneutralinomasspiesoft
trackTRT(?) pT(?) (?) TRTMarch 29, 2008*56cm107cmICEPP26aZE-6
event display March 29, 2008*electronTRThit()
(B.1) hitsingle particlefull simulationTRThit/100% TrackSi(pixel+SCT) slepton (chargino)3: a few %March 29, 2008*noiseparticle hits
192430hit~5~10~15
(B.3) Zmuon, pT>20GeV, |h|5
(B.3) single charginoTRT hitpionelectron3nsec1
AMSBStudySCTstudy
Cnon-pointingMarch 29, 2008*
(C.1) non-pointingATLASh pointing geometryhg h granularity non-pointingsensitive (f
Trigger, ID
March 29, 2008*MiddleFrontr0EM shower 60 GeVEM shower 60 GeVgranularity (Dh x Df)pointingnon-pointing
EM Cal Barrel End-capFront layer0.003 x 0.10.00{3,6} x0.1Middle layer0.025 x 0.0250.025 x 0.025
event display 3March 29, 2008*
GMSBSUSYJet, MissingET photon
Photon menuL1 -- 2g menuHigher LVL --
Jet, MissingET menuphoton
March 29, 2008*(C.2) non-pointingtriggerpointing (ct = 1.1mm)non-pointing (ct = 3.2m)photon menujet, mEt menu
(C.3) non-pointingg-non-pointingoptimizeDh = 0 95%Dh=0.575%g-IDATLAS10g(X)()
March 29, 2008*Dh = h - hMCct =1.0mct =3.2mConversionneutralino decay length in Z(mm)neutralino decay length in Z(mm)
(C.3) non-pointingg-cut(5/10)
gFake ID JetrejectionMarch 29, 2008*Standard IDOptimized IDct=1.1mmct=1.0mct=3.2mct~4pre-filtere=0.082 BG4
(C.3) neutralinorobustZ pointing MC IDCalorimeterEMneutralinobMarch 29, 2008*
original Toptimized IDstandard ID3.17ns3.0+/-0.2 ns1.33+/-0.0510.7ns(19+/-19 ns)2.9+/-0.6
BACKUP SLIDESMarch 29, 2008*
Physics model for R-hadronsQuark system interactsGluino is just a reservoir of kinetic energyInteractions are thought to be pomeron / reggeon mediated:Interactions ofFigure: A.C. Kraan
Photon ID variablesMarch 29, 2008*
(A) trigger for slow heavy particles (slepton, R-hadron)The fate of the hadron-collider exp. Data cannot be analyzed unless it is triggered !Heavy penetrating particles are triggered as muons, generally produced in pairsinclusive high-pT single muon menu
must reach the last trigger stations in time for coincidence
if faster one triggers in right bunch crossing, the other can be reconstructed in offline
March 29, 2008*GMSB Slepton M=100GeVb spectrumnumber of Muon triggercandidates (b, acceptance)GMSB Slepton M=100GeV
pT thresholdLuminosity20GeVLow (1033cm-2/s-1)40GeVHigh (1034cm-2/s-1)rate estimates are on-going discussion, menu not fixed yet
March 29, 2008*
(B) trigger for non-pointing photonsevent topology much looks like a general SUSY signaturewill use ordinary SUSY trigger menu i.e. EtMiss + Jetsfeasibility to use the standard photon menu, or its extension is currently under investigationMarch 29, 2008*jetjetjetemggCALIDmissingmissingATLAS Prelim.ATLAS Std. photon trigger menudh = h(point) h(geom)trigger (EF) efficiencyw.r.t. non-point MC photon (leading pT>60GeV)
menucondition2g20i2 isolated photons pT>20GeVg601 photon pT>60GeV
(B) Reconstruction of non-pointing photonsglobal goal of the non-pointing photon is the observation the decay length measurements which directly connects to SUSY scaleefficiency, resolution in terms of degree of non-pointing March 29, 2008*dh = h(point) h(geom)ATLAS Prelim.ATLAS Prelim.ATLAS Prelim.dh (Rec -- Truth)resol. < 0.002Incident angle dependenceBarrel Only
(B) Reconstruction of the non-pointing photonswith g only, decay vertex cannot be reconstructedinstead looking at inter section z reconstruction is ok, std photon ID has strong dependence the work on-going for non-pointing ID : save the non-pointing while keep the bkg rejectionusage of LAr timing, photon conversion is a next plan March 29, 2008*ATLAS Prelim.EM shower 60 GeVbeam axisz0MC pT>60GeVReconstructionstd. IDs(tight/loose)Z distribution (cm)recovery of ID-efficiency(removing h width cut on 2nd layer)ATLAS Prelim.Barrelonly