4 páginas, 1 figura.-- Trabajo presentado a la Fifth Conference on Physics at LHC celebrada en Hamburgo (Alemania) del 7 al 12 de junio de 2010.We analyze the potential of the first LHC physics run, assuming 1 fb−1 at ps = 7 TeV, to

discover Supersymmetry (SUSY). The results are based on SUSY parameter fits following a

frequentist approach. They include the experimental constraints from electroweak precision

data, (g − 2)μ, B physics and cosmological data. The two SUSY models under consideration

are the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking

mass parameters, and a model with common non-universal Higgs mass parameters in the

superpotential (NUHM1). We find that large parts of the regions preferred at the 68%

C.L. are accessible to early LHC running.Work

supported in part by the European Community’s Marie-Curie Research Training Network under

contract MRTN-CT-2006-035505 ‘Tools and Precision Calculations for Physics Discoveries at

Colliders’ (HEPTOOLS).Peer reviewe

Chalabi, Khaled

Gunther, R. W.

Haage, P.

Schürmann, K.

Vorwerk, D.

We analyze the potential of the first LHC physics run, assuming 1/fb at sqrt[s] = 7 TeV, to discover Supersymmetry (SUSY). The results are based on SUSY parameter fits following a frequentist approach. They include the experimental constraints from electroweak precision data, (g-2)_mu, B-physics and cosmological data. The two SUSY models under consideration are the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking mass parameters, and a model with common non-universal Higgs mass parameters in the superpotential (NUHM1). We find that large parts of the regions preferred at the 68% C.L. are accessible to early LHC running

Heinemeyer, S.

DESY Publication Database

Discovering SUSY in the First LHC Run

DESY

4 páginas, 1 figura.-- Trabajo presentado a la Fifth Conference on Physics at LHC celebrada en Hamburgo (Alemania) del 7 al 12 de junio de 2010.We analyze the potential of the first LHC physics run, assuming 1 fb−1 at ps = 7 TeV, to
discover Supersymmetry (SUSY). The results are based on SUSY parameter fits following a
frequentist approach. They include the experimental constraints from electroweak precision
data, (g − 2)μ, B physics and cosmological data. The two SUSY models under consideration
are the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking
mass parameters, and a model with common non-universal Higgs mass parameters in the
superpotential (NUHM1). We find that large parts of the regions preferred at the 68%
C.L. are accessible to early LHC running.Work
supported in part by the European Community’s Marie-Curie Research Training Network under
contract MRTN-CT-2006-035505 ‘Tools and Precision Calculations for Physics Discoveries at
Colliders’ (HEPTOOLS).Peer reviewe

Heinemeyer, Sven

Digital.CSIC

Discovering SUSY in the first LHC runSven HeinemeyerInstituto de F´ısica de Cantabria (CSIC-UC), Santander, SpainDOI: http://dx.doi.org/10.3204/DESY-PROC-2010-01/253We analyze the potential of the first LHC physics run, assuming 1 fb−1 at√s = 7 TeV, todiscover Supersymmetry (SUSY). The results are based on SUSY parameter fits following afrequentist approach. They include the experimental constraints from electroweak precisiondata, (g − 2)µ, B physics and cosmological data. The two SUSY models under consider-ation are the constrained MSSM (CMSSM) with universal soft supersymmetry-breakingmass parameters, and a model with common non-universal Higgs mass parameters in thesuperpotential (NUHM1). We find that large parts of the regions preferred at the 68%C.L. are accessible to early LHC running.1 IntroductionOne of the main tasks of the LHC is to search for physics beyond the Standard Model (SM),where Supersymmetry (SUSY) is one of the favored ideas. The first physics run of the LHCis currently ongoing at√s = 7 TeV, aiming for 1 fb−1 until the end of 2011. Here we reviewthe results from frequentist analyses [1, 2] of the parameter spaces of the constrained minimalsupersymmetric extension of the Standard Model (CMSSM) — in which the soft SUSY-breakingscalar and gaugino masses are each constrained to universal values m0 and m1/2, respectively— and the NUHM1 — in which the soft SUSY-breaking contributions to the Higgs masses areallowed to have a different but common value. Both models have a common trilinear couplingA0 at the GUT scale and tanβ (the ratio of the two vacuum expectation values) as a low-energyinput. A detailed list of references on the subject of frequentist (and bayesian) analyses can befound in Ref. [1].2 Details of the fitsThe results obtained in Refs. [1, 2] include various experimental results: B-physics observables(such as rates for BR(b→ sγ) and BR(Bu → τντ ), and the upper limit on BR(Bs → µ+µ−)) aswell as K-physics observables, precision electroweak data (such as the W boson mass and theanomalous magnetic moment of the muon, (g − 2)µ), the bound on the lightest MSSM Higgsboson mass, Mh, and the cold dark matter (CDM) density (as inferred from astrophysicaland cosmological data) assuming that this is dominated by the relic density of the lightestneutralino, Ωχh2.The fit is performed by using a global χ2 likelihood function, which combines all theoreticalPLHC2010 1291predictions with experimental constraints:χ2 =N∑i(Ci − Pi)2σ(Ci)2 + σ(Pi)2+M∑i(fobsSMi − ffitSMi)2σ(fSMi)2+ χ2(Mh) + χ2(BR(Bs → µµ)) + χ2(SUSY search limits) (1)Here N is the number of observables studied, Ci represents an experimentally measured value(constraint), and each Pi defines a prediction for the corresponding constraint that depends onthe supersymmetric parameters. The experimental uncertainty, σ(Ci), of each measurement istaken to be both statistically and systematically independent of the corresponding theoreticaluncertainty, σ(Pi), in its prediction. We denote by χ2(Mh) and χ2(BR(Bs → µµ)) the χ2contributions from two measurements for which only one-sided bounds are available so far.Similarly, we include the lower limits from the direct searches for SUSY particles at LEP [3] asone-sided limits, denoted by “χ2(SUSY search limits)” in Eq. (1). The experimental constraintsused in our analyses are listed in Table 1 of Ref. [1]. Our statistical treatment of the CMSSMand NUHM1 makes use of a large sample of points (about 2.5× 107) in the SUSY parameterspaces obtained with the Markov Chain Monte Carlo (MCMC) technique. Our analysis isentirely frequentist, and avoids any ambiguity associated with the choices of Bayesian priors.The main computer code for our evaluations is the MasterCode [1,2,4–6], which includes thefollowing theoretical codes. For the RGE running of the soft SUSY-breaking parameters, it usesSoftSUSY [7], which is combined consistently with the codes used for the various low-energyobservables: FeynHiggs [8–11] is used for the evaluation of the Higgs masses and aSUSYµ (seealso [12,13]), for the other electroweak precision data we have included a code based on [14,15],SuFla [16,17] and SuperIso [18,19] are used for flavor-related observables, and for dark-matter-related observables MicrOMEGAs [20] and DarkSUSY [21] are included. In the combination of thevarious codes, MasterCode makes extensive use of the SUSY Les Houches Accord [22, 23].3 SUSY discovery potential of the first LHC runFor the parameters of the best-fit CMSSM point we find m0 = 60 GeV, m1/2 = 310 GeV,A0 = 130 GeV, tanβ = 11 and µ = 400 GeV, yielding the overall χ2/Ndof = 20.6/19 (36%probability) and nominally Mh = 114.2 GeV. The corresponding parameters of the best-fitNUHM1 point are m0 = 150 GeV, m1/2 = 270 GeV, A0 = −1300 GeV, tanβ = 11 and m2h1 =m2h2 = −1.2× 106 GeV2 or, equivalently, µ = 1140 GeV, yielding χ2 = 18.4 (corresponding toa similar fit probability as in the CMSSM) and Mh = 120.7 GeV.In Fig. 1 we display the best-fit value and the 68% and 95% likelihood contours for theCMSSM (upper plot) and the NUHM1 (lower plot) in the (m0,m1/2) plane, obtained as de-scribed above from a fit taking into account all experimental constraints. We also show exclusioncontours for the hadronic search mode (jets plus missing energy) at CMS. The green (light gray)solid line shows the 95% C.L. exclusion contour for CMS for 1 fb−1 at√s = 7 TeV [24]. Theblack solid line shows the corresponding results for only 0.1 fb−1. (Similar results hold forATLAS.) One can see that with 1 fb−1 the best-fit points can be tested, together with a sizablepart of the whole 68% C.L. preferred regions. In the case of the NUHM1 (lower plot) nearlythe whole 68% C.L. region could be probed.In conclusion, if the CMSSM or the NUHM1 (or a very similar SUSY model) were realizedin nature, the first LHC physics run at√s = 7 TeV until the end of 2011 could reveal already2 PLHC2010SVEN HEINEMEYER92first signals of SUSY. On the other hand, no indication of SUSY-like signatures would alreadyseverly restrict these (kind of) GUT based models.4 AcknowledgmentsWe thank O. Buchmu¨ller, R. Cavanaugh, A. De Roeck, J. Ellis, H. Fla¨cher, G. Isidori, K. Olive,F. Ronga and G. Weiglein with whom the results presented here have been obtained. Worksupported in part by the European Community’s Marie-Curie Research Training Network undercontract MRTN-CT-2006-035505 ‘Tools and Precision Calculations for Physics Discoveries atColliders’ (HEPTOOLS).References[1] O. Buchmueller et al., Eur. Phys. J. C 64 (2009) 391.[2] O. Buchmueller et al., JHEP 0809 (2008) 117.[3] LEP Supersymmetry Working Group, see: http://lepsusy.web.cern.ch/lepsusy/ .[4] O. Buchmueller et al., Phys. Lett. B 657 (2007) 87.[5] O. Buchmueller et al., Phys. Rev. D 81 (2010) 035009.[6] See http://cern.ch/mastercode .[7] B. C. Allanach, Comput. Phys. Commun. 143 (2002) 305.[8] S. Heinemeyer, W. Hollik and G. Weiglein, Comput. Phys. Commun. 124 (2000) 76.See http://www.feynhiggs.de .[9] S. Heinemeyer, W. Hollik and G. Weiglein, Eur. Phys. J. C 9 (1999) 343.[10] G. Degrassi et al., Eur. Phys. J. C 28 (2003) 133.[11] M. Frank et al., JHEP 0702 (2007) 047.[12] T. Moroi, Phys. Rev. D 53 (1996) 6565 [Erratum-ibid. D 56 (1997) 4424].[13] S. Heinemeyer, W. Hollik and G. Weiglein, Phys. Rept. 425 (2006) 265.[14] S. Heinemeyer et al., JHEP 0608 (2006) 052.[15] S. Heinemeyer, W. Hollik, A. Weber and G. Weiglein, JHEP 0804 (2008) 039.[16] G. Isidori and P. Paradisi, Phys. Lett. B 639 (2006) 499.[17] G. Isidori, F. Mescia, P. Paradisi and D. Temes, Phys. Rev. D 75 (2007) 115019, and references therein.[18] F. Mahmoudi, Comput. Phys. Commun. 178 (2008) 745.[19] D. Eriksson, F. Mahmoudi and O. Stal, JHEP 0811 (2008) 035.[20] G. Belanger, F. Boudjema, A. Pukhov and A. Semenov, Comput. Phys. Commun. 176 (2007) 367; ibid.149 (2002) 103; ibid. 174 (2006) 577.[21] P. Gondolo et al., New Astron. Rev. 49 (2005) 149.[22] P. Skands et al., JHEP 0407 (2004) 036.[23] B. Allanach et al., Comput. Phys. Commun. 180 (2009) 8.[24] CMS Note-2010/008.PLHC2010 3DISCOVERING SUSY IN THE FIRST LHC RUN293Figure 1: The (m0,m1/2) plane in the CMSSM (upper plot) and the NUHM1 (lower plot).The dark shaded area at low m0 and high m1/2 is excluded due to a scalar tau LSP, the lightshaded areas at low m1/2 do not exhibit electroweak symmetry breaking. Shown in both plotsare the best-fit point, indicated by a filled circle, and the 68 (95)% C.L. contours from our fit asdark gray/blue (light gray/red) overlays, scanned over all tanβ and A0 values. The 95% C.L.exclusion curves (hadronic search channel) at CMS with 1 (0.1) fb−1 at 7 TeV center-of-massenergy is shown as green/light gray (black) solid curve.4 PLHC2010SVEN HEINEMEYER294

Discovering SUSY in the first LHC run

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