Focus-Point studies at LHC U. De Sanctis, T. Lari, C. Troncon University of Milan and INFN ATLAS Collaboration Focus-Point studies at LHC EuroGDR Frascati 25/11/2004 T. Lari Focus Point

SUSY and Dark Matter DM  SUSY Non-baryonic matter density, computed from WMAP measurements: 0.094 < WDM h2 < 0.129 (2s confidence interval) For any specific set of parameters of a SUSY R-parity conserving model, it is possible to compute the LSP relic density from the mass spectrum and the Big-Bang cosmology. The relic density can be less than WDM (if other contributions to the DM). The WMAP upper limit is a constrain that defines cosmologically interesting regions of the SUSY parameter hyperspace. I will limit myself to mSUGRA here. SUSY  DM Once (if) we will have a measurement of SUSY mass spectrum mixing angle etc., one can compute the relic density it corresponds to. EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

mSUGRA and DM SUSY spectrum computed with ISAJET 7.69 In most of mSUGRA parameter space the predicted relic density is too large. In the Focus-Point region (large m0) the lightest neutralino has a significant Higgsino component, and the relic density is reduced by s-channel annihilation in the early universe. SUSY spectrum computed with ISAJET 7.69 Relic density computed with Micromegas 1.3.0 Focus Point Coannihilation (very narrow) Selected for a detailed study with ATLAS simulation. EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Comparison of RGE codes m0 scan m1/2 = 300 GeV tanb = 10 A0=0 m >0 mt=175 GeV Large differences in the predicted relic density using different codes to compute SUSY mass spectrum at the Electro-Weak scale. The study presented here was made using ISAJET 7.69. Wh2 3000 4000 m0 (GeV) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

SUSY mass spectrum Mass spectrum at the selected point Masses (GeV) ~ M0=3400 GeV m1/2 = 300 GeV tanb = 10 A0=0 m >0 mt=175 GeV Masses (GeV) ~ c01 102.6 c02 157.4 c03 172.3 c04 290.5 c1 145.4 c2 282.7 g 854 qL 3416 t1 2041 h 118. 8 ~ ~ ~ ~ ~ ~ ~ ~ Squarks at the limit of LHC reach. Other sleptons and heavy Higgs too heavy for LHC. Gluino decays into neutralinos and charginos. EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Production xSection Sum of jet and missing transverse energy. using ATLAS fast simulation Production xSections ~ ~ cc 4.6 pb gg 0.58 pb qg 3.7 fb ~ ~ ~ ~ 10 fb-1 (1st LHC year?) Susy/√SM = 16 cc production most abundant, but little jet and missing energy: difficult to separate from SM. We are investigating the possibility to use c±1c02 → c01 l± c01 l+ l- searching for 3 leptons+missing energy+no jet events. gluino pair production dominant after standard SUSY cuts. squarks visible with high luminosity Standard cuts (not optimized for this point) on jet and missing energy and lepton veto. EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Gluino decays Gluino decays: g → c0 qq 7.2 % g → c0 bb 3.7 % g → c0 tt 28.0 % g → c0 g 5.9 % g → c qq 9.6 % g → c tb 45.6 % Golden channel is the neutralino dilepton decay (gives neutralino mass difference). In principle, the leptons from neutralino decays can be combined with jets to get further mass relations. However, large number of jets from gluino decay (heavy combinatory background) and poor lepton statistics to start with. We have concentrated on reconstruction of the two main gluino decays using tt and tb invariant mass distributions (gives difference between gluino and gaugino mass scales) Neutralino dilepton decays: c03 → c01 l l c02 → c01 l l EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Dilepton mass distributions The c02 edge can be measured (constrain on neutralino mixing matrix from the shape?) The c03 edge hardly visible even after three years at design luminosity. At generator level ATLAS ~ ~ c02 → c01 l+l- Experimental, flavour subtracted ~ ~ ~ ~ c03 → c01 l+l- ATLAS ~ 20 40 60 Mll (GeV) 300 fb-1 No SM background Cuts: Meff > 750 GeV, ETmiss > 100 GeV, 1 jet with pT > 100 GeV Leptons with pT > 10 GeV 20 40 60 80 Mll (GeV) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Gluino decays to chargino Top quark decay into udb or csb fully reconstructed. tb invariant masses reconstructed. 30 fb-1 No SM background ATLAS M(g)-M(c1) 33 fb-1 no SM backg. M(g)-M(c2) 200 400 600 Mtb (GeV) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Gluino to neutralino g → c04 tt g → c03 tt g → c02 tt g → c01 tt Invariant mass of two fully reconstructed tops. Analysis cuts similar to the gluino to chargino analysis. With high luminosity an endpoint can be extracted. At generator level Experimental, flavour subtracted ATLAS ATLAS ~ ~ g → c04 tt 300 fb-1 No SM background ~ ~ g → c03 tt ~ ~ g → c02 tt ~ ~ g → c01 tt 400 600 800 400 600 800 Mtt (GeV) Mtt (GeV) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Scan of parameter space As one moves up the FP strip the SUSY masses increase and the production cross sections decrease. FP2 FP3 FP4 FP5 M0 3400 4200 5720 6000 M1/2 300 500 1000 Wh2 .059 .026 .078 .012 M(g) 854 1334 2453 2468 M(c01) 103 176 401 241 s(gg) 580 21.3 0.05 s(cc) 4600 1074 57 480 s(gq) 3.7 0.2 M0-m1/2 scan for mt=175 GeV,A0=0,tanb=10,m>0 FP5 FP4 Gluino mass FP3 FP2 Cross sections in fb, masses in GeV EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Neutralino mass differences The c02 is close in mass to c01 on the right of the band (where W << WWMAP) while it is close to the c03 on the left of the band (where W ~ WWMAP). Almost always m(c02)-m(c01) is below the threshold for c02 → c01 Z0 The dilepton edge would provide a good constrain on W. M(c02)-M(c01) M(c03)-M(c02) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Effect of top mass M1/2 (GeV) M1/2 (GeV) Mt = 175 GeV 500 500 100 100 2000 5000 2000 4000 M0 (GeV) As the top mass is increased the FP region moves to larger values of m0. For the same m1/2 the gluino/gaugino masses and decays depend very little on the top mass. Sfermions are within LHC reach only for a light top. Mt = 178 GeV 500 100 2000 5000 M0 (GeV) EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Effect of top mass At fixed m1/2 = 300 GeV, relation between mtop and m0 for the FP region. tanb=10,A0=0,m>0 FP6 FP2 FP7 FP8 mtop 172 175 178 183 M0 1900 3400 7130 30850 M1/2 300 Wh2 .066 .059 .077 .0827 M(g) 814 854 904 1011 M(c01) 102 103 108 106 s(gg) 703 580 412 202 s(cc) 4610 4600 3650 4130 s(gq) 110 3.7 FP8 FP7 FP2 FP6 EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Effect of tanb tanb=10 tanb=54 FP2 FP10 FP11 tanb=30 A larger value of tanb pushes the FP band to lower values of m0 At FP11 abundant squark production! FP9 EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Conclusions Part of the Focus-Point region is accessible by the LHC experiments. A test point was studied with the ATLAS detector fast simulation. A number of mass constrains can be measured: m(c02)-m(c01), m(g)-m(c±) and m(g)-m(c0). A scan of mSUGRA focuspoint space has been performed with ISAJET to study how the SUSY mass spectrum varies and select points for more detailed studies. The gluino gets heavier as one moves along the band in the m0-m1/2 plane. The LHC reach to observe gluino pair production should be about m1/2 ~ 900 GeV. Gaugino production may be used to extend this reach, assuming it can be isolated from the SM background. The neutralino spectrum is sensitive to position both along and trasversal to the band. The squarks are accessible for low top masses and/or high tanb - this would allow to get m0 (and confirm that sfermions are there…) The Focus-Point is under active study by the ATLAS collaboration. All results are preliminary and more are coming. EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Horizontal line scan (III) Not really any good solution with SOFTSUSY EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

Comparison of RGE codes (2) Comparison for point M0=3400 GeV m1/2 = 300 GeV tanb = 10 A0=0 m >0 mt=175 GeV ISAJET 7.69 SOFTSUSY 1.86 SPheno 2.22 Suspect 2.3 M(c01) 102.6 126.9 127.0 M(c02) 157.4 247.7 248.6 247.4 M(c03) 172.3 596.4 665.4 580.8 M(g) 853.7 858.1 807.7 869.0 M(uL) 3419 3481 3431 All masses in GeV EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies

One more table Little effect from changing the sign of m FP12 FP2 FP9 FP10 FP11 mtop 10 30 54 M0 3400 2400 2300 1400 M1/2 300 180 m - + W .061 .059 .091 .052 .114 M(g) 854 829 825 517 M(uL) 3416 2449 2356 1435 M(t1) 2041 1479 1427 860 M(c01) 111 103 107 68 s(gg+gq) 580 700 1314 16670 s(cc) 4550 4610 4600 3650 4130 Little effect from changing the sign of m mh = 114.8 GeV EuroGDR Frascati 25/11/2004 T. Lari Focus Point studies