Mohamad-Ziad Charif - Antares

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Figure 2.9: Parameter space of m 1/2 and m 0 plane with constrains on the LSP.Green region is where the predicted Ω c is in agreement with WMAP.• Tri-linear scalar couplings on the GUT scale: A 0• The ratio of the vacuum expectation values of the neutral components of thetwo Higgs doublets 〈Hu 0 〉 and 〈Hd 0 v2〉 at the electro-weak scale: tan(β) =v1• Sign of the higgsino mass parameter µ (+1 or -1)Having four parameters (plus sign(µ)) is much easier to deal with, and constrainingmodels is something now extremely easy to do.The lightest supersymmetric particle in this model is usually the lightest of theneutralinos which are a mixing of the four superpatners ( ˜B, ˜W 3 , ˜H u 0 and ˜Hd 0 ) of theneutral gauge bosons and higgs of the electro-weak section of Standard Model (B,W 3 , Hu 0 and Hd 0 ). The neutralinos are neutral and colorless making the lightest ofthem a natural candidate for WIMPs. Additionally, inspection of various regionsof the parameters space showed that many regions of the space produce the correctrelic density Ω c as we can see in figure 2.9.Finally it is important to note that while LHC is constraining the parameter space(m ˜q, ˜g > 1TeV ), there have not been any constraining on the neutralino mass sofar in addition to those from the LEP, leaving a reduced parameter space that isstill valid for consideration. In addition, CMSSM is used as a general benchmark,so it will be used during this thesis as a benchmark scenario for WIMP studies aswell.18
2.3 Methods of detection2.3.1 Direct detectionDirect detection of dark matter refers to the detection of dark matter via its scatteringoff nucleus in a detector, causing transfer of momentum to the target nucleusand forcing it to recoil. Direct detection experiments use different techniquesfor detection (scintillation, phonon, and ionization) depending on the material ofthe detector (Ge, Si, NaI, and Xenon). The physics in dark matter nucleus interactioninvolves elastic scattering on nucleus, this scattering can be axial-vectorgiving rise to spin-dependent scattering or scalar giving rise to spin-independentscattering. Experiments using heavy nuclei such as the Iodine, Germanium orXenon like DAMA[32], Edelweiss[33], SuperCDMS[34], XENON[35], and othersare more sensitive to scalar interactions and their limits are mainly constrainingthe spin-independent WIMP-nucleon cross-section. On the other hands experimentsusing light nuclei are more sensitive to spin-dependent such as COUPP[36],SIMPLE[37] and NAIAD[38].The spin-independent scattering amplitude can be written as follows[39] in equation2.14 and the cross-section in equation 2.15, where N denotes the nucleontype, λ N is WIMP nuclei coupling, m χ and M N are the WIMP and nucleon massrespectively, A is the atomic mass and Z the atomic number.|A SI | 2 = 64(m χ M N ) 2 (λ p Z + λ n (A − Z)) 2 (2.14)σ SI =4m 2 χM 2 Nπ(m χ + M N ) 2 .(λ pZ + λ n (A − Z)) 2 (2.15)The spin-dependent scattering amplitude and cross section can be written as follows[39]in equations 2.16 & 2.17, where J is the angular momentum of the nuclei, and Sis the spin of the nuclei where it takes the value of 0 for nuclei that have an evennumber of protons and neutrons and 0.5 for all other.|A SD | 2 = 192(m χ M N ) 2 (2.16)σ SD =16m 2 χMN2π(m χ + M N ) 2 .J A + 1(J A∑ ε i Si A ) 2 (2.17)i=p,nFindings in direct detection has yielded some results that might indicate thepresence of a light dark matter particle. DAMA experiment claims the observationof a dark matter signal[40]. This signal corresponds to annual modulation in theirdata that is related to Earth’s rotation around the Sun. However, while these resultsare with an extremely high statistical significance (above 6σ), these results are in19
Page 2 and 3: "The most exciting phrase to hear i
Page 4 and 5: 3.2.1.4 Performance and characteris
Page 6 and 7: Chapter 1IntroductionThe early hist
Page 8 and 9: Chapter 2Dark MatterIn this chapter
Page 10 and 11: Figure 2.2: Comparison of the measu
Page 12 and 13: Figure 2.4: CMB anisotropy observed
Page 14 and 15: Figure 2.5: Combination of the WMAP
Page 17: Figure 2.6: Temporal evolution of t
Page 22 and 23: Figure 2.10: Limits on spin-indepen
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Page 28 and 29: 600km/s. If we assume the worst cas
Page 30 and 31: Figure 2.17: Conversion factor from
Page 32 and 33: The eigenstate mixing can be writte
Page 34 and 35: Figure 2.19: Flux of ν µ / ¯ν
Page 36 and 37: Figure 3.1: The neutral current (NC
Page 38 and 39: Muon Energy (GeV )1p| dEdx | (GeV.c
Page 40 and 41: Figure 3.4: Energy loss of per dist
Page 42 and 43: Figure 3.6: Effective muon range as
Page 44 and 45: Figure 3.8: Differential flux of at
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Page 48 and 49: • The LED (light emitting diode)
Page 50 and 51: Anchor & BuoyEach line is anchored
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Figure 4.4: Average neutrino events
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2. All hits on the same floor are m
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4.2.1 Neutrino simulationFigure 4.6
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• Multiplicity range of the muon
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Chapter 5Dark Matter search in the
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Figure 5.2: Annihilation spectrum f
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Livetime(days) 5 Lines 9 Lines 10 L
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Figure 5.4: Monte Carlo Truth distr
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Figure 5.7: Tchi2 distribution for
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Figure 5.9: Tchi2 distribution for
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Figure 5.11: Sun’s position taken
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Figure 5.13: Comparison between the
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Figure 5.15: Estimation of the back
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Figure 5.16: Mean angle between the
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Figure 5.18: A comparison of the di
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a look at figure 5.22 we find a cle
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The resulting optimized sensitiviti
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Figure 5.26: A comparison plot of t
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dΦ µdE ν= dΦ νdE νP earth ρN
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Figure 5.31: Limits on the muon flu
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Chapter 6Dark Matter search in the
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Figure 6.1: . True Position of the
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Figure 6.3: Comparison of the three
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For BBFit all variables mentioned i
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Figure 6.6: The distribution of χ
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annihilation channel W + W − the
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lowering the total contribution of
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6.4.2 BBFit Single-line analysisThe
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Figure 6.15: Comparison between the
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Figure 6.17: Comparison of Nhit dis
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Figure 6.19: The estimation of the
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Figure 6.21: Comparison of the opti
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Figure 6.23: Comparison of sensitiv
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Figure 6.25: Estimation of our back
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Figure 6.28: Comparison of the mult
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Figure 6.29: Comparison of the Λ d
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Figure 6.31: Comparison of the cos(
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Figure 6.34: Comparison of the esti
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The optimal Λ cut for all dark mat
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Figure 6.40: Sensitivity to neutrin
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6.7 Comparison with 2007-2008 analy
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mass of 200 GeV and a cross-section
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Chapter 7ConclusionsThe limits pres
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Bibliography[1] Volders, L. M. J. S
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[22] S. Burles et al., “Big bang
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[46] G. Debrassi, S. Heinemeyer, W.
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[74] C. Hettlage, K. Mannheim, and
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[102] D. Heck and J. Knapp, “Fors
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Mohamad-Ziad Charif - Antares

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