ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D01 Search for Extra-Dimensions at pp and ep Colliders Eric Kajfasz, CPPM/D0 for the CDF, D0, H1 and Zeus collaborations _
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D02 Extra Dimensions: Outline Extra Dimension Models and Signatures studied at CDF & D0 Run II, H1 and ZEUS Preliminary results on virtual graviton/gauge boson exchange and direct graviton emission Summary and Conclusions Why ED? o come “naturally” with string theory o provide mechanism to explain why M EW << M PL o...
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D03 Extra Dimensions: Models Explored focus on n extra dims in models where SM fermions live on a D3-brane: Large Extra Dimensions (LED) Arkani-Hamed,Dimopoulos,Dvali Phys Lett B429 (98) o M PL ~ GeV o n >= 2 compact and flat - M S : string/fundamental scale M 2 PL ~ R n M S n+2 => M S can be lowered to TeV scale o gravitons propagate in the bulk => Kaluza-Klein tower G (k) o can’t resolve successive modes (0.01eV:n=2; 1MeV:n=3; 100MeV:n=6) => expect: virtual exchange of graviton KK modes real graviton emission TeV -1 Extra Dimension (TeV -1 ) Dienes,Dudas,Gherghetta Nucl Phys B537 (99) o M C : compactification scale (~ TeV) o gauge fields can propagate in the bulk => KK towers of gauge bosons o modes with nearly equal energy spacing ~TeV o lower GUT scale by changing running of the couplings => expect: resonances at high energies (LHC...) virtual exchange (Hera, Tevatron)
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D04 Warped Extra Dimension (RS) Randull,Sundrum Phys Rev Lett 83 (99) o ED of size R, highly curved, compactified on S 1 /Z 2 orbifold: y = R . o Zero mode graviton G (0) localized at the Planck-brane (y = 0) o SM fields localized on TeV-brane (y = R ) o metric: ds 2 = e -2kR dx dx – R 2 d 2 k: curvature scale for kR ~ 11-12, = M PL e -kR ~ TeV o consistency => 0.01 < k/M PL 0.1 o Gravitons propagate in the bulk => KK tower G (n) of modes of mass m n = x n ke -kR (x n : 1 st Bessel func. zeros i.e. 3.83, 7.02, 10.17,...) => well separated modes = m 1 M PL /(kx 1 ) => model characterized by m 1 and k/M PL o => Look for first graviton resonance Extra Dimensions: Models Explored... y y=0 y=R
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D05 Extra Dimensions: Topologies Explored KK q q _ ee, , G q q _ g(jet), jet(s) + MET + MET Exchange Virtual Gravitons (LED,TeV -1,RS) Emission of Real Gravitons (LED) KK e e jet p Tevatron Hera
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D06 Large Extra Dimensions Virtual Graviton Exchange G (n) _ /Z f f G (n) f f f f _ _ dilepton channel (Tevatron) diphoton channel (Tevatron) DIS channel (Hera) G (n) SM
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D07 Large Extra Dimensions Virtual Graviton Exchange Effect of ED parameterized by a single variable: different formalisms have different definitions of M S : o Hewett: (Hewett, Phys Rev Lett 82, 4765 (99) ) F = 2 / with = ± 1 o GRW: (Giudice, Rattazzi, Wells, hep-ph/ ) F = 1 o HLZ: (Han, Lykken, Zhang, hep-ph/ ) F = log(M S 2 /s) for n = 2 F = 2/(n-2) for n > 2 G = F/ M S 4 = SM + G int + G 2 KK
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D08 Large Extra Dimensions: Virtual Graviton Exchange 2 isolated e’s, E T > 25 GeV e’s coming from luminous region MET significance cut CC = 92.4 ± 0.4% CP = 79.2 ± 0.5% for M ee > 350 GeV: N exp = 4.6, N obs = 8 M ee distrib. used in binned likelihood => Limits on G = /M S 4 CC+CP C (entral) : | |<1 P (lug) : 1<| |<3 M ee 95% CL limits on M S (TeV) ee
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D09 Large Extra Dimensions: Virtual Graviton Exchange diEM = combine ee and o 2 EM objects, E T > 25 GeV with track isolation o overall ID efficiency: 85 ± 1 % for M diEM > 350 GeV: N exp = 9.7 (1.6 QCD), N obs = 8 Systematics: ~ 12% CC-CC + CC-EC CC: | |<1.1 EC: 1.5<| |<2.4 signal for G = pb -1 diEM QCD D-Y+ direct + QCD CC-CC + CC-EC
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D010 Large Extra Dimensions: Virtual Graviton Exchange Run II Run I+II Data agree with SM predictions => M diEM vs|cos *| distrib. used in 2D Binned Likelihood =>Set limits on G alone or in combination with Run I results => give 95% CL limits on M S (TeV) Most stringent constraints on LED for n > 2 to date among all experiments. 200pb -1 diEM
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D011 Large Extra Dimensions: Virtual Graviton Exchange 250pb -1 2 ’s with P T > 15 GeV o isolated, | |<2.0 o cosmic veto o M > 50 GeV for M > 300 GeV: N exp = 6.4 and N obs = 5 Systematics: ~ 13% D0 RunII Preliminary M vs|cos *| distr. used in 2D Binned Likelihood => Set limits on G => 95% CL limits on M S (TeV)
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D012 Large Extra Dimensions:HERA Virtual Graviton Exchange G (k) Virtual exchange in t-channel interferes with Deep Inelastic Scattering (DIS) Small contribution ~ O(1%) from eg -> eg G (k) exchange affects the Q 2 distribution at high Q 2 Compare d /dQ 2 to what is expected from SM Q 2 = (k-k’) 2 = -q 2,KK
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D013 Large Extra Dimensions: Virtual Graviton Exchange Hewett formalism DIS H1s 1/2 (GeV)L int (pb -1 ) e + p30136 e + p31965 e - p31916 2 fit of d /dQ 2 no deviation from SM => Set limits on G => 95% CL limits on M S (TeV)
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D014 Large Extra Dimensions: Virtual Graviton Exchange Hewett formalism: = - 1 : M S > 0.79 TeV = + 1 : M S > 0.78 TeV DIS Zeuss 1/2 (GeV)L int (pb -1 ) e + p301/ e - p31916 d /dQ 2 used in binned likelihood => Set limits on G => 95% CL limits on M S (TeV)
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D015 Large Extra Dimensions: Direct Graviton Emission Graviton produced along with a jet disappears in the bulk, undetected => mono-jet like topology with high MET n = 6 and M S = 0.7 TeV Final Selection: o MET > 150 GeV o P T (jet1) > 150 GeV, | | < 1 o P T (jet2) < 50 GeV (MET,jet1) > 30 o N exp = ± 6.3 (stat) ± 7.5 (theo) (JES) N obs = 63 (~ 5% efficiency) QCD MC SM bkg: mostly Z-> +jet(s) 85pb -1 MSMS n (K = 1) updated analysis with 200pb -1 and new JES in process... limits on M S ~ GeV jet(s)+MET
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D016 TeV -1 Extra Dimension: Virtual Exchange of Z/ KK states (> 1 EM w/ track match) same procedure as for LED analysis but with virtual Z/ KK states effects parameterized by: C = 2 /3M C 2 N exp = 12.1 (4.3 QCD), N obs = 9 => Limit set as done for LED: C M C > % CL KK states modify the Z/ propagators: 1/Q 2 -> 1/Q 2 + C 1/(Q 2 +M Z 2 ) -> 1/(Q 2 +M Z 2 ) + C Fit to e + p and e - p data => M C > % CL D0: ee H1: DIS 200pb -1 signal for C = 5 TeV -2 from combined precision EW measurements: M C > 6.6 TeV LEP QCD D-Y+ QCD
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D017 RS Extra Dimension Graviton KK states well separated => resonant graviton search: CDF analyses: o ee and : binned likelihood method o counting limits using 3 mass window around resonance D0 analysis: o diEM: using 3 mass window method
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D018 RS Extra Dimension ee data agree with expected SM bkg... ee, , ee : 2 isolated e’s w/ E T >25GeV CC or CP : 2 isolated ’s w/ P T >20GeV | 1 | <1, | 2 |<1.5 cosmic veto : 2 isolated ’s w/ E T >15GeV CC
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D019 RS Extra Dimension ee ee, , cross-section limits computed from binned likelihood (ee, ) and 3- mass window ( ) compare to R-S cross- section for different values of the k/M PL parameter. => exclusion contour plot...
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D020 RS Extra Dimension Lower limits on M G (GeV) for k/M PL = 0.1 ee ee, , Further improvement can be achieved by: using mass window method for dilepton channels combining channels
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D021 RS Extra Dimension signal RS Graviton M G = 300 GeV same diEM data set as for LED search data agree with expected SM background => set limits with mass window method diEM 200pb GeV QCD D-Y+ direct + QCD CC-CC + CC-EC
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D022 Summary LED = -1 M S (TeV) > = +1 M S (TeV) > CDF D0 diEM D0/I+II diEM D0 H ZEUS RS M G (GeV) PL =0.1 CDF 605 CDF ee 620 CDF 690 D0 ee 660 D0 diEM 785 TeV -1 M C (TeV) > D01.12 H11.0 LEP6.6 n MSMS (K = 1)
ICHEP ’04, Beijing, August 20, 2004Eric Kajfasz, CPPM/D023 Conclusions Tevatron, CDF&D0 working well CDF&D0 have by now each ~ 450pb -1 on tape Tevatron and HERA are great tools to start looking for ED’s Very competitive results and even most stringent limits are starting to come out There is still room for improvement, so stay tuned. However, for the final word on some models, we may very well need to wait for LHC...