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Review
. 2015;75(8):371.
doi: 10.1140/epjc/s10052-015-3511-9. Epub 2015 Aug 14.

Physics at the [Formula: see text] linear collider

Affiliations
Review

Physics at the [Formula: see text] linear collider

G Moortgat-Pick et al. Eur Phys J C Part Fields. 2015.

Abstract

A comprehensive review of physics at an [Formula: see text] linear collider in the energy range of [Formula: see text] GeV-3 TeV is presented in view of recent and expected LHC results, experiments from low-energy as well as astroparticle physics. The report focusses in particular on Higgs-boson, top-quark and electroweak precision physics, but also discusses several models of beyond the standard model physics such as supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analysed as well.

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Figures

Fig. 1
Fig. 1
The achievable precision in the different Higgs couplings at the LHC on bases of 3ab-1 and 50 % improvement in the theoretical uncertainties in comparison with the different energy stages at the ILC. In the final LC stage all couplings can be obtained in the 1–2 % range, some even better [39]
Fig. 2
Fig. 2
Simulated measurement of the background-subtracted tt¯ cross section with 10 fb-1 per data point, assuming a top-quark mass of 174 GeV in the 1S scheme with the ILC luminosity spectrum for the CLIC-ILD detector [40]
Fig. 3
Fig. 3
Statistical precision on CP-conserving form factors expected at the LHC [42] and at the ILC [41]. The LHC results assume an integrated luminosity of L=300 fb-1. The results for the ILC are based on an integrated luminosity of L=500 fb-1 at s=500 GeV and a beam polarisation of Pe-=±80%, Pe+=30% [41]
Fig. 4
Fig. 4
Equivalence of the SUSY electroweak Yukawa couplings gW~, gB~ with the SU(2), U(1) gauge couplings g, g. Shown are the contours of the polarised cross sections σL(e+e-χ~10χ~20) and σR(e+e-χ~10χ~20) in the plane of the SUSY electroweak Yukawa couplings normalised to the gauge couplings, YL=gW~/g, YR=gB~/g [43, 44] for a scenario with the electroweak spectrum similar to the reference point SPS1a
Fig. 5
Fig. 5
Polarised cross sections versus Pe- (bottom panel) and Pe+ (top panel) for e+e-e~e~-production with direct decays in χ~10e in a scenario where the non-coloured spectrum is similar to a SPS1a-modified scenario but with me~L=200 GeV, me~R=195 GeV. The associated chiral quantum numbers of the scalar SUSY partners e~L,R can be tested via polarised e±-beams
Fig. 6
Fig. 6
WIMP mass as a function of the mass for p-wave (J0=1) annihilation and under the assumption that WIMP couplings are helicity- and parity-conserving in the process e+e-γχχ [48]. With an integrated luminosity of L=500 fb-1 and polarised beams with Pe-=+80%, Pe+=-60% with ΔP/P=0.25% the reconstructed WIMP mass can be determined with a relative accuracy of the order of 1 % [49]. The blue area shows the systematic uncertainty and the red bands the additional statistical contribution. The dominant sources of systematic uncertainties are ΔP/P and the shape of the beam-energy spectrum
Fig. 7
Fig. 7
Combined limits for fermionic dark matter models. The process e+e-χχγ is assumed to be detected only by the hard photon. The analysis has been modelled correspondingly to [49] and is based on L=500 fb-1 at s=500 GeV and s=1 TeV and different polarisations [50, 51]
Fig. 8
Fig. 8
Achievable precision on sin2θ23 from bi-linear R-parity-violating decays of the χ~10 as a function of the produced number of neutralino pairs compared to the current precision from neutrino oscillation measurements [52]
Fig. 9
Fig. 9
Theoretical prediction for sin2θeff in the SM and the MSSM (including prospective parametric theoretical uncertainties) compared to the experimental precision at the LC with GigaZ option. A SUSY inspired scenario SPS 1a’ has been used, where the coloured SUSY particles masses are fixed to 6 times their SPS 1a’ values. The other mass parameters are varied with a common scale factor
Fig. 10
Fig. 10
New gauge bosons in the μ+μ- channel. The plot shows the expected resolution at CLIC with s=3 TeV and L=1 ab-1 on the ‘normalised’ vector vfn=vfs/(mZ2-s) and axial-vector afn=afs/(mZ2-s) couplings to a 10 TeV Z in terms of the SM couplings vf, af. The mass of Z is assumed to be unknown, nevertheless the couplings can be determined up to a two-fold ambiguity. The colours denote different Z models [9, 10]
Fig. 11
Fig. 11
Upper plot Event in Higgs-strahlung e+e-ZH(μ+μ-)(jetjet) for a Higgs mass of 125 GeV at a collider energy of 500 GeV; lower plot Distribution of the recoiling Higgs decay jets
Fig. 12
Fig. 12
Upper plot Threshold rise of the Cross section for Higgs-strahlung e+e-ZH corresponding to Higgs spin =0,1,2, complemented by the analysis of angular correlations; lower plot Measurements of Higgs couplings as a function of particle masses
Fig. 13
Fig. 13
Upper plot reconstructed 2-jet invariant mass for associated production: e+e-AHbb¯bb¯ for a Higgs mass of 900 GeV at a collider energy of 3 TeV; lower plot similar plot for e+e-H+H-tb¯t¯b
Fig. 14
Fig. 14
Displays of example Higgs-boson candidate events. Top HZZ2μ2e candidate in the ATLAS detector; bottom VBF Hγγ candidate in the CMS detector
Fig. 15
Fig. 15
Reconstructed distributions of the Higgs boson candidate decay products for the complete 2011/2012 data, expected backgrounds, and simulated signal from top the ATLAS Hγγ [101], centre the CMS HZZ4 [102], and bottom the ATLAS HWW22ν [103] analyses
Fig. 16
Fig. 16
Evidence for the decay Hττ. Top CMS observed and predicted mττ distributions [109]. The distributions obtained in each category of each channel are weighted by the ratio between the expected signal and signal-plus-background yields in the category. The inset shows the corresponding difference between the observed data and expected background distributions, together with the signal distribution for a SM Higgs boson at mH=125 GeV; bottom ATLAS event yields as a function of log(S/B), where S (signal yield) and B (background yield) are taken from the corresponding bin in the distribution of the relevant BDT output discriminant [110]
Fig. 17
Fig. 17
Higgs boson signal strength as measured by ATLAS for different decay channels [112]
Fig. 18
Fig. 18
Higgs-boson production strength, normalised to the SM expectation, based on CMS analyses [113], for a combination of analysis categories related to different production modes.
Fig. 19
Fig. 19
Likelihood for the ratio μVBF/μggF+ttH obtained by ATLAS for the combination of the Hγγ, ZZ4 and WW2ν2 channels and mH=125.5 GeV [112]
Fig. 20
Fig. 20
Preliminary ATLAS results of fits for a two-parameter benchmark model that probes different coupling strength scale factors common for fermions (κF) and vector bosons (κV), respectively, assuming only SM contributions to the total width. Shown are 68 and 95 % CL contours of the two-dimensional fit; overlaying the 68 % CL contours derived from the individual channels and their combination. The best-fit result (×) and the SM expectation (+) are also indicated [112]
Fig. 21
Fig. 21
Test of custodial symmetry: CMS likelihood scan of the ratio λWZ, where SM coupling of the Higgs bosons to fermions are assumed [113]
Fig. 22
Fig. 22
Constraining BSM contributions to particle loops: CMS 2d likelihood scan of gluon and photon coupling modifiers κg, κγ [113]
Fig. 23
Fig. 23
Summary plot of CMS likelihood scan results [113] for the different parameters of interest in benchmark models documented in [38]. The inner bars represent the 68 % CL confidence intervals, while the outer bars represent the 95 % CL confidence intervals
Fig. 24
Fig. 24
ATLAS summary of the fits for modifications of the SM Higgs-boson couplings expressed as a function of the particle mass. For the fermions, the values of the fitted Yukawa couplings for the Hff¯ vertex are shown, while for vector bosons the square-root of the coupling for the HVV vertex divided by twice the vacuum expectation value of the Higgs boson field [112]
Fig. 25
Fig. 25
CMS mass measurements [113] in the γγ and ZZ4 final states and their combinations. The vertical band shows the combined uncertainty. The horizontal bars indicate the ±1 standard deviation uncertainties for the individual channels
Fig. 26
Fig. 26
Observed transverse mass distributions for the ATLAS ZZ22ν analysis [115] in the signal region compared to the expected contributions from ggF and VBF Higgs production with the decay HZZ SM and with μoff-shell=10 (dashed) in the 2e2ν channel. A relative ggZZ background K-factor of 1 is assumed
Fig. 27
Fig. 27
CMS likelihood scan versus ΓH. Different colours refer to: combination of 4 low-mass and high-mass (ochre), combination of 4 low-mass and 22ν high-mass and combination of 4 low-mass and both channels at high-mass (blue). Solid and dashed lines represent observed and expected limits, respectively [116]
Fig. 28
Fig. 28
Top final-state observables sensitive to the spin and parity of the decaying resonance in ZZ4 final states. Bottom cosθ1 distribution for ATLAS data (point with errors), the backgrounds (filled histograms) and several spin hypotheses (SM solid line and alternatives dashed lines) [119]
Fig. 29
Fig. 29
Distributions of the test statistic q=-2ln(LJP/L0+) for the spin-1 and spin-2 JP models tested against the SM Higgs boson hypothesis in the combined XZZ and WW analyses [117]. The expected median and the 68.3, 95.4, and 99.7 % CL regions for the SM Higgs boson (orange, the left for each model) and for the alternative JP hypotheses (blue, right) are shown. The observed q values are indicated by the black dots
Fig. 30
Fig. 30
Projected a diphoton mass distribution for the SM Higgs boson signal and background processes after VBF selection and b background-subtracted dimuon mass distribution based on ATLAS simulations assuming an integrated luminosity of 3000 fb-1 [138]
Fig. 31
Fig. 31
Relative uncertainty on the signal strength determination expected for the ATLAS experiment [136]. Assuming a SM Higgs boson with a mass of 125 GeV and 300 fb-1 and 3000 fb-1 of 14 TeV data. The uncertainty pertains to the number of events passing the experimental selection, not to the particular Higgs boson process targeted. The hashed areas indicate the increase of the estimated error due to current theory systematic uncertainties
Fig. 32
Fig. 32
Expected ATLAS 68 and 95 % CL likelihood contours for κV and κF in a minimal coupling fit for an integrated luminosity of 300 fb-1 and 3000 fb-1 [136]
Fig. 33
Fig. 33
CMS projected relative uncertainty on the measurements of κγ, κV, κg, κb, κt, and κτ assuming s=14 TeV and an integrated luminosity 300 and 3000 fb-1. The results are shown for two uncertainty scenarios described in the text [137]
Fig. 34
Fig. 34
Relative uncertainty expected for the ATLAS experiment on the determination of coupling scale factor ratios λXY=κX/κY from a generic fit [136], assuming a SM Higgs boson with a mass of 125 GeV and 300 fb-1 and 3000 fb-1 of 14 TeV data. The hashed areas indicate the increase of the estimated error due to current theory uncertainties
Fig. 35
Fig. 35
Fit results for the reduced coupling scale factors for weak bosons and fermions as a function of the particle mass, assuming 300/fb or 3000/fb of 14 TeV data and a SM Higgs boson with a mass of 125 GeV [136]
Fig. 36
Fig. 36
Projected diphoton mass distribution for signal and background processes based on ATLAS simulations for a search for Higgs boson pair production with subsequent decays Hbb¯ and Hγγ assuming an integrated luminosity of 3000 fb-1 [139]. The simulated distributions are scaled to match the expected event yields but do not necessarily reflect the corresponding statistical fluctuations
Fig. 37
Fig. 37
The origin of XVV coupling and its relation to the mass term of V
Fig. 38
Fig. 38
XZZ decay and e+e-ZX process
Fig. 39
Fig. 39
Mass–coupling relation [144]
Fig. 40
Fig. 40
Two proposed detector concepts for the ILC: ILD (left) and SiD (right) [147]
Fig. 41
Fig. 41
Why 250–500 GeV? The three thresholds
Fig. 42
Fig. 42
Cross sections for the three major Higgs production processes as a function of centre-of-mass energy
Fig. 43
Fig. 43
Recoil mass distribution for the process: e+e-Zh followed by Zμ+μ- decay for mh=125 GeV with 250 fb-1 at s=250 GeV [151]
Fig. 44
Fig. 44
Threshold scan of the e+e-Zh process for mh=120 GeV, compared with theoretical predictions for JP=0+, 1-, and 2+ [156]
Fig. 45
Fig. 45
Determination of CP mixing with 1σ bands expected at s=350 GeV and 500 fb-1 [158]
Fig. 46
Fig. 46
Cross sections for the signal tt¯h process with and without the non-relativistic QCD (NRQCD) correction together with those for the background processes: tt¯Z,tt¯g(gbb¯) and tt¯ (upper plot). The invariant mass distribution for the tt¯ subsystem with and without the NRQCD correction (lower plot)
Fig. 47
Fig. 47
Cross sections for the double Higgs production processes, e+e-Zhh and e+e-νν¯hh, as a function of s for mh=120 GeV
Fig. 48
Fig. 48
Diagrams contributing to a e+e-Zhh and b e+e-νν¯hh
Fig. 49
Fig. 49
(Upper plot) cross section for e+e-Zhh at s=500 GeV normalised by that of the SM as a function of the self-coupling normalised by that of the SM. (Lower plot) a similar plot for e+e-νν¯hh at s=1 TeV
Fig. 50
Fig. 50
Expected mass–coupling relation for the SM case after the full ILC programme
Fig. 51
Fig. 51
Comparison of the capabilities of the LHC and the ILC, when the ILC data in various stages: ILC1 with 250 fb-1 at s=250, ILC: 500 fb-1 at 500 GeV, and ILCTeV: 1ab-1 at 1 TeV are cumulatively added to the LHC data with 300 fb-1 at 14 TeV [197]
Fig. 52
Fig. 52
Comparison of the model-discrimination capabilities of the LHC and the ILC [200]
Fig. 53
Fig. 53
Comparison of the model-discrimination capabilities of the LHC and the ILC [200]
Fig. 54
Fig. 54
Comparison of the model-discrimination capabilities of the LHC and the ILC [200]
Fig. 55
Fig. 55
Possible machine upgrade scenarios for the ILC [141, 201]
Fig. 56
Fig. 56
Longitudinal cross section of the top quadrant of CLIC_SiD (left) and CLIC_ILD (right) [9, 10]
Fig. 57
Fig. 57
Reconstructed particles in a simulated e+e-H+H-tb¯t¯b event at s=3 TeV in the CLIC_ILD detector including the background from γγhadrons before (left) and after (right) applying tight timing cuts on the reconstructed cluster times [9, 10]
Fig. 58
Fig. 58
Search reach in the mA-tanβ plane for LHC and CLIC. The left-most coloured regions are current limits from the Tevatron with 7.5 fb-1 of data at s=1.96 TeV and from fb-1 of LHC data at s=7 TeV. The black line is projection of search reach at LHC with s=14 TeV and 300 fb-1 of luminosity [211]. The right-most red line is search reach of CLIC in the HA mode with s=3 TeV. This search capacity extends well beyond the LHC [9, 10]
Fig. 59
Fig. 59
Di-jet invariant mass distributions for the e+e-HAbb¯bb¯ (left) and the e+e-H+H-tb¯t¯b (right) signal together with the individual background contributions for model I [9, 10].
Fig. 60
Fig. 60
Di-jet invariant mass distributions for the e+e-HAbb¯bb¯ (left) and the e+e-H+H-tb¯t¯b (right) signal together with the individual background contributions for model II [9, 10]
Fig. 61
Fig. 61
MAtanβ plane in the mhmax scenario (upper) and in the mhmod+ scenario (lower plot) [238]. The green-shaded area yields Mh125±3GeV, the red area at high tanβ is excluded by LHC heavy MSSM Higgs-boson searches, the blue area is excluded by LEP Higgs searches, and the red strip at low tanβ is excluded by the LHC SM Higgs searches
Fig. 62
Fig. 62
Fit for the light CP-even Higgs mass in the CMSSM (left) and NUHM1 (right) [254]. Direct searches for the light Higgs boson are not included
Fig. 63
Fig. 63
Stop mixing parameter Xt/mq~3 vs. the light stop mass (left), and the light vs. heavy stop masses (right), see text
Fig. 64
Fig. 64
The decay branching ratios of H, A and H± in 2HDMs for Type I, Type II, Type X and Type Y as a function of tanβ with mH=mA=mH±=250 GeV and sin(β-α)=1 [295]
Fig. 65
Fig. 65
The constraint on the parameter space in the 2HDM for Type I, Type II, Type IV (Type X) and Type III (Type Y) from various flavour experiments [311]
Fig. 66
Fig. 66
Expected exclusion regions (2σ CL) in the plane of tanβ and the mass scale mϕ of the additional Higgs bosons at the LHC. Curves are evaluated by using the signal and background analysis given in Ref. [338] for each process, where the signal events are rescaled to the prediction in each case [339, 340], except the 4τ process for which we follow the analysis in Ref. [341]. Thick solid lines are the expected exclusion contours by L=300 fb-1 data, and thin dashed lines are for L=3000 fb-1 data. For Type-II, the regions indicated by circles may not be excluded by H/Aτ+τ- search by using the 300 fb-1 data due to the large SM background
Fig. 67
Fig. 67
Contour plots of the four-particle production cross sections through the H / A production and H± production process at the ILC with s=500  GeV in the (mH±,tanβ) plane. Contour of σ=0.1 fb is drawn for each signature [295]
Fig. 68
Fig. 68
Contour plots of the four-particle production cross sections through the H / A production and H± production process at the ILC with s=1  TeV in the (mH±,tanβ) plane. Contour of σ=0.1 fb is drawn for each signature [295]
Fig. 69
Fig. 69
Left the scaling factors in 2HDM with four types of Yukawa interactions. Right the scaling factors in models with universal Yukawa couplings. The current LHC bounds and the expected LHC and ILC sensitivities are also shown at the 68.27 % CL. For details, see Refs. [339, 340]
Fig. 70
Fig. 70
Predictions of various scale factors on the κτ vs. κb (upper panel), and κτ vs κc (bottom panel) in four types of Yukawa interactions in the cases with cos(β-α)<0 [293, 294]. Each black dot shows the tree-level result with tanβ=1, 2, 3 and 4. One-loop corrected results are indicated by red for sin2(β-α)=0.99 and blue for sin2(β-α)=0.95 regions where mΦ and M are scanned over from 100 GeV to 1 TeV and 0 to mΦ, respectively. All the plots are allowed by the unitarity and vacuum stability bounds
Fig. 71
Fig. 71
Contour plots of the deviation in the hhh coupling in the (mΦ,M) plane for mh=125 GeV and sin(β-α)=1. The red line indicates φc/Tc=1, above which the strong first order phase transition occurs (φc/Tc>1) [363, 364]
Fig. 72
Fig. 72
Constraints from the unitarity and vacuum stability bounds for λ1=mh2/(2v2)0.13 in the λ4λ5 plane. We take λΔ=1.5 for the left panel and λΔ=3 for the right panel with λΔ=λ2=λ3 [375]
Fig. 73
Fig. 73
Decay branching ratio of H++ as a function of vΔ. In the left figure, mH++ is fixed to be 300 GeV, and Δm is taken to be zero. In the middle figure, mH++ is fixed to be 320 GeV, and Δm is taken to be 10 GeV. In the right figure, mH++ is fixed to be 360 GeV, and Δm is taken to be 30 GeV
Fig. 74
Fig. 74
Decay branching ratio of H++ as a function of vΔ with mH+=mH++. The solid, dashed and dotted curves, respectively, show the results in the case of mH++=150, 300 and 500 GeV [375]
Fig. 75
Fig. 75
The signal cross section as a function of mH++ with the collision energy to be 7 TeV from Ref. [399]. The light (dark) shaded band shows the 95 % CL (expected) upper bound for the cross section from the data with the integrate luminosity to be 4.7 fb-1 (20 fb-1)
Fig. 76
Fig. 76
Production cross section of the e+e-H++H-- process as a function of mH++. The black, blue and red curves are, respectively, the results with the collision energy s=250, 500 and 1000 GeV
Fig. 77
Fig. 77
The invariant mass distribution (left panel) and the transverse mass distribution (right panel) for the ++ and ++Emiss systems, respectively, in the case of mH++=230 GeV and s=500 GeV [375]. The integrated luminosity is assumed to be 500 fb-1
Fig. 78
Fig. 78
The scaling factors in models with universal Yukawa couplings. The current LHC bounds and the expected LHC and ILC sensitivities are also shown at the 68.27 % CL. For details, see Ref. [340]
Fig. 79
Fig. 79
Higgs boson branching ratios in MCHM5 as a function of ξ for Mh=125 GeV
Fig. 80
Fig. 80
Generic Feynman diagrams contributing to Higgs pair production via Higgs-strahlung off Z bosons
Fig. 81
Fig. 81
Generic Feynman diagrams contributing to Higgs pair production via W boson fusion
Fig. 82
Fig. 82
The ZHH (upper two) and WW fusion (lower two) cross sections in the SM (red) and the MCHM5 for ξ=0.2 (blue), ξ=0.5 (black) and ξ=0.8 (green) divided by the cross section of the corresponding model at κ=1, as a function of κ, for s=500 GeV and s=1 TeV
Fig. 83
Fig. 83
Summary plot of the current constraints and prospects for direct and indirect probes of Higgs compositeness. The dark brown region shows the current LHC limit from direct search for vector resonance. The dark (medium light) horizontal purple bands indicate the sensitivity on ξ expected at the LHC from double (single) Higgs production with 300 fb-1 of integrated luminosity. The pink horizontal band reports the sensitivity reach on ξ from the study of double Higgs processes alone at CLIC with 1ab-1 of integrated luminosity at 3 TeV, while the light-blue horizontal band shows the sensitivity reach on ξ when considering single Higgs processes. Finally, experimental electroweak precision tests (EWPT) favour the region below the orange thick line with and without additional contributions to Δρ. From Ref. [441]
Fig. 84
Fig. 84
Scan over the Higgs-portal potential Eq. 68. We include the constraints from electroweak precision measurements
Fig. 85
Fig. 85
95% confidence level contours for a measurement of Γ1hid/Γ1SM at the LHC and a 350GeV LC. We use Sfitter [459] for the LHC results and we adopt the linear collider uncertainties of reference [458]
Fig. 86
Fig. 86
Measurement of a hypothetical portal model at a 350 GeV linear collider, uncertainties are adopted from Ref. [458]. A measurement of R2 at the LHC, with only an upper 95 % confidence level bound on J2 does not constrain the region Γ2hid/Γtot,2SM below the J2 curve. This degeneracy is lifted with a measurement at a linear collider
Fig. 87
Fig. 87
The reduced signal cross section R1bb at a e+e- collider as defined in the text, as a function of MH1 in the semiconstrained NMSSM (from [482])
Fig. 88
Fig. 88
The reduced signal cross section R2bb as function of MH1 in the semiconstrained NMSSM (from [482]).
Fig. 89
Fig. 89
Higgs production cross sections at a e+e- collider in the channels ZH1, ZH2, H+H- and HiAj for a point in the parameter space of the semiconstrained NMSSM with Higgs masses as indicated in the text, from [492]
Fig. 90
Fig. 90
The reduced coupling Rγγ, as defined in Eq. (81), as function of Mchargino1 for MASMHS260 GeV, for a scenario explaining a 130 GeV photon line from dark matter annihilation in the galactic centre
Fig. 91
Fig. 91
The reduced coupling Rγγ as a function of MAS, for points in the semiconstrained NMSSM where HS with MHS100 GeV explains the excess in bb at LEP II (from [492]; orange diamonds satisfy the WMAP constraint on the dark matter relic density)
Fig. 92
Fig. 92
The reduced coupling Rγγ as a function of MHS, for points in the semiconstrained NMSSM where HS with MHS100 GeV explains the excess in bb at LEP II (from [492]; orange diamonds satisfy the WMAP constraint on the dark matter relic density)
Fig. 93
Fig. 93
Accessible range of Γ(hgg) and Γ(hγγ) normalised to the SM value in the LLH model (from [524])
Fig. 94
Fig. 94
The Γ(hgg) normalised to the SM value (from [528]). The fmin is defined as the smallest value allowed by electroweak precision measurements and the values are 1.2 TeV for the LLH model, 500 GeV for T-parity case, 700 GeV for custodial littlest Higgs model and 500 GeV for minimal composite Higgs model, respectively (for details, see [528])
Fig. 95
Fig. 95
The (a) shows the total decay width normalised to the SM value in the LHT (from [526]). The difference between case A and case B comes from the definition of the down-type Yukawa term (for details, see [526]). The (b) shows the partial Higgs branching ratios normalised to the SM value (from [526])
Fig. 96
Fig. 96
The distribution of γγ and eγ centre-of-mass energy W with respect to the e+e- energy (2E0) from simulation of the PLC luminosity spectra [603]. Contributions of various spin states of produced system are shown
Fig. 97
Fig. 97
Distributions of the corrected invariant mass, Wcorr, for selected bb¯ events; contributions of the signal, for MHSM= 120 GeV, and of the different background processes, are shown separately [613]
Fig. 98
Fig. 98
Ratio Γ(hγγ)Γ(hγγ)SM as a function of the mass scale of the new physics f in the Littlest Higgs model [524], for different Higgs-boson masses. “Accessible” indicates the possible variation of the rate for fixed f labelfig
Fig. 99
Fig. 99
Top production of A and H, with parameters corresponding to the LHC wedge, at the γγ collider. Exclusion and discovery limits obtained for NLC collider for ee=630 GeV, after 2 or 3 years of operation [642], Bottom the case MH=MA=300 GeV at χVH0 in the MSSM. Distributions of the corrected invariant mass Wcorr for selected bb¯ events at tanβ=7 [643]
Fig. 100
Fig. 100
The specific decay angular distributions Σi in the γγh(i)tt¯ process in dependence on the tt¯ invariant mass for the scalar (dashed) and pseudoscalar (thick solid) h(i) with MH=400 GeV [649]
Fig. 101
Fig. 101
The top quark production cross section R for mt=170GeV and three values for top quark width. The LO formula for the cross section and αs(30GeV)=0.142 is used
Fig. 102
Fig. 102
Total cross section for top quark production near threshold at NNNLO (with an estimated third order matching coefficients) and NNLO from [761], where a scale variation of (20-80)GeV is shown by the coloured bands. A top quark PS mass mPS(20GeV)=175GeV is used
Fig. 103
Fig. 103
The threshold cross section at fixed order (upper pannel) and renormalisation group improvement (lower pannel) is shown from Ref. [756]. The bands between two coloured lines at each orders show the scale dependence of the results. The RG improved cross sections are stable against scale variation, while fixed order result suffers from large dependence on values of μs
Fig. 104
Fig. 104
Corrections due to Higgs exchange in e+e-tt¯. In the left diagram the Higgs exchange contributes to the production vertex for γtt¯,Ztt¯, which occurs at short distance when the tt¯-pair is separated by r1/mt. In the right diagram Higgs exchanges occurs after bound-state formation between top and anti-top quarks separated by the scale of the bound state r1/(mtαs)
Fig. 105
Fig. 105
Cross section for e+e-tt¯ for mt=170GeV with/without one-loop Higgs boson corrections. A Higgs-boson mass of mh=125GeV is used
Fig. 106
Fig. 106
Top quark momentum distribution at ΔE=E-E1=0,2,5 GeV (top) for mt=170 GeV and top-quark mass dependence (bottom) on the momentum distribution
Fig. 107
Fig. 107
Dependence of the forward–backward asymmetry AFB on the top quark width (upper plot) and the strong coupling αs (lower plot). Figures are taken from Ref. [779]
Fig. 108
Fig. 108
The top-quark production cross section calculated with TOPPIK for a top mass of 174 GeV in the 1S mass scheme, showing the effects of initial-state radiation and of the luminosity spectrum of CLIC. Figure taken from Ref. [40]
Fig. 109
Fig. 109
Simulated measurement of the background-subtracted tt¯ cross section with 10 fb-1 per data point, assuming a top-quark mass of 174 GeV in the 1S scheme with the ILC luminosity spectrum for the CLIC_ILD detector. Figure taken from Ref. [40]
Fig. 110
Fig. 110
Simulated measurement of the top-quark invariant mass in the all-hadronic decay channel of top-quark pairs for an integrated luminosity of 100 fb-1 at CLIC in the CLIC_ILD detector at a centre-of-mass energy of 500 GeV. The solid green histogram shows the remaining non tt¯ background in the data sample. The mass is determined with an unbinned maximum likelihood fit to the distribution. Figure taken from Ref. [40]
Fig. 111
Fig. 111
Statistical precision on MW from the Voigtian fit (see text)
Fig. 112
Fig. 112
Prediction for MW as a function of mt. The plot shows the MW prediction assuming the light CP-even Higgs h in the region 125.6±3.1GeV. The red band indicates the overlap region of the SM and the MSSM with MHSM=125.6±3.1 GeV. All points are allowed by HiggsBounds. The grey ellipse indicates the current experimental uncertainty, whereas the red ellipse shows the anticipated future ILC/GigaZ precision
Fig. 113
Fig. 113
Theoretical prediction for sin2θeff in the SM and the MSSM (including prospective parametric theoretical uncertainties) compared to the experimental precision at the LC with GigaZ option. An SPS 1a inspired scenario is used, where the squark and gluino mass parameters are fixed to 6 times their SPS 1a values. The other mass parameters are varied with a common scale factor
Fig. 114
Fig. 114
MSSM parameter scan for MW and sin2θeff over the ranges given in Eq. (116) with mt=165175GeV. Todays 68 % CL ellipses (from AFBb(LEP), ALRe(SLD) and the world average) are shown as well as the anticipated GigaZ/MegaW precisions, drawn around todays central value
Fig. 115
Fig. 115
Loop contribution of the top quark to the Higgs-boson mass
Fig. 116
Fig. 116
Δχ2 profiles as a function of the Higgs mass for electroweak fits compatible with an SM Higgs boson of mass 125.8 GeV (left) and 94 GeV (right), respectively. The measured Higgs-boson mass is not used as input in the fit. The grey bands show the results obtained using present uncertainties [890], and the yellow bands indicate the results for the hypothetical future scenario given in Table 28 (left plot) and corresponding input data shifted to accommodate a 94 GeV Higgs boson but unchanged uncertainties (right plot). The right axes depict the corresponding Gaussian ‘sigma’ lines. The thickness of the bands indicates the effect from the theoretical uncertainties treated according to the Rfit prescription. The long-dashed line in each plot shows the curves one would obtain when treating the theoretical uncertainties in a Gaussians manner just like any other uncertainty in the fit
Fig. 117
Fig. 117
Δχ2 profiles as a function of the Higgs mass for electroweak fits compatible with an SM Higgs boson with mass 94 GeV using the LEPEWWG approach [21]. The blue (pink) parabola shows the current (future) fit (see text)
Fig. 118
Fig. 118
a SUSY contributions to aμ for the SPS benchmark points (red), and for the “degenerate solutions” from Ref. [910]. The yellow and blue band indicate the current and an improved experimental result, respectively. b Possible future tanβ determination assuming that a slightly modified MSSM point SPS1a (see text) is realised. The bands show the Δχ2 parabolas from LHC data alone (yellow) [911], including the aμ with current precision (dark blue) and with prospective precision (light-blue). The width of the blue curves results from the expected LHC uncertainty of the parameters (mainly smuon and chargino masses) [911]. Taken from [912]
Fig. 119
Fig. 119
Comparison of Δκγ and Δλγ at different machines. For LHC and ILC 3 years of running are assumed (LHC: 300 fb-1, ILC s=500 GeV: 500 fb-1, ILC s=800 GeV: 1000 fb-1). If available the results from multi-parameter fits have been used. Taken from [269]
Fig. 120
Fig. 120
Discovery reach of the ILC with s=0.5 (1.0) TeV and Lint=500 (1000) fb-1. The discovery reach of the LHC for s=14 TeV and 100 fb-1 via the Drell–Yan process pp+-+X are shown for comparison. From Ref. [997] with kind permission of The European Physical Journal (EPJ)
Fig. 121
Fig. 121
Top Resolving power (95 % CL) for MZ=1,1.5, and 2 TeV and s=500 GeV, Lint=1 ab-1, |Pe-|=80 %, |Pe+|=60 %, for leptonic couplings based on the leptonic observables σ, ALR, AFB. The couplings correspond to the E6 χ, LR, LH, and KK models. From Ref. [1000]. Bottom Expected resolution at CLIC with s=3 TeV and L=1 ab-1 on the “normalised” leptonic couplings of a 10 TeV Z in various models, assuming lepton universality. The mass of the Z is assumed to be unknown. The couplings correspond to the E6 χ, η, and ψ, the SSM, LR, LH and SLH models. The couplings can only be determined up to a two-fold ambiguity. The degeneracy between the ψ and SLH models might be lifted by including other channels in the analysis (tt¯, bb¯,...). From Refs. [9, 10, 1001]
Fig. 122
Fig. 122
Neutralino relic density as a function of the neutralino LSP mass from a scan of the pMSSM parameter space. The colours indicate the nature of the neutralino LSP with the largest occurrence in each bin
Fig. 123
Fig. 123
Limits on the χp spin-independent scattering cross section vs. the χ10 mass. The shaded regions include MSSM points compatible with recent LHC SUSY searches and Higgs mass results [1098]. Also indicated is the most stringent recent limit from the LUX experiment [1099]
Fig. 124
Fig. 124
Neutralino–nucleon spin-independent scattering cross section vs. the χ10 mass. The colours indicate the nature of the neutralino LSP with the largest occurrence in each bin
Fig. 125
Fig. 125
95 % CL exclusion limits for MSUGRA/CMSSM models with tanβ=30, A0=-2m0 and μ>0 presented in the [M0,M1/2] plane obtained by the ATLAS experiment with 20 fb-1 of data at 8 TeV (from [1117])
Fig. 126
Fig. 126
95 % CL exclusion limits on the chargino–neutralino production NLO cross section times branching fraction in the flavour-democratic scenario, for the three-lepton (upper panel), dilepton WZ + MET and trilepton (lower panel) CMS searches with 9.2 fb-1 of data at 8 TeV (from [1122])
Fig. 127
Fig. 127
Plot of ΔEW contours in the m1/2 vs. μ plane of NUHM2 model for A0=-1.6m0 and m0=5 TeV and tanβ=15. We also show the region accesses by LHC8 gluino pair searches, and the region accessible to LHC14 searches with 300 fb-1 of integrated luminosity. We also show the reach of various ILC machines for higgsino pair production. The green-shaded region has Ωχ~10stdh2<0.12. Figure from [1132]
Fig. 128
Fig. 128
Sparticle production cross sections vs. s at a Higgsino factory for a radiatively driven natural SUSY benchmark point [1064]
Fig. 129
Fig. 129
Di-jet mass (upper plots) and energy spectra (lower plots) for chargino and neutralino production at 0.5 TeV (from [207])
Fig. 130
Fig. 130
Di-jet invariant mass distribution in inclusive 4-jet + missing energy SUSY events produced in s=3 TeV e+e- collisions for 0.5 ab-1 of fully simulated events. The result of the fit to extract the boson content is shown by the continuous line with the individual W, Z and h components represented by the dotted lines (from [1162])
Fig. 131
Fig. 131
Energy spectrum of reconstructed τ leptons from τ~1 decays (left) and energy distribution of the pions from 1-prong decays with the fit for the determination of the polarisation for fully simulated e+e- events at 0.5 TeV (from [207])
Fig. 132
Fig. 132
The threshold excitation (a) and the angular distribution (b) in pair production of smuons in the MSSM, compared with the first spin-1/2 Kaluza–Klein muons in a model of universal extra dimensions; for details, see Ref. [1172]
Fig. 133
Fig. 133
a The unpolarised cross section of e+e-μ~R+μ~R- production close to threshold, including QED radiation, beamstrahlung and width effects; the statistical errors correspond to L=10fb-1 per point, b energy spectrum Eμ from μ~R-μ-χ~10 decays; polar-angle distribution cosθμ~R c with and d without contribution of false solution. The simulation for the energy and polar-angle distribution. The simulation for the energy and polar-angle distribution is based on polarised beams with (Pe-,Pe+)=(+0.8,-0.6) at s=1TeV and L=500fb-1. For details, see Ref. [1172]
Fig. 134
Fig. 134
Polarised cross section versus P(e-) (left panel) or P(e+) (right panel) for e+e-e~e~-production with direct decay in χ~10e in a scenario where the non-coloured spectrum is similar to a SPS1a-modified scenario but with me~L=200 GeV, me~R=195 GeV [45]
Fig. 135
Fig. 135
Electron and positron energy distributions for selectron pair production with the indicated beam polarisations and an integrated luminosity of 50 fb-1 at s=500 GeV (E. Goodman, U. Nauenberg et al. in Ref. [12])
Fig. 136
Fig. 136
Left the total cross sections for pair production of wino-like neutralinos near threshold in the MSSM and the Dirac theory. Right dependence of the cross sections on the production angle θ for s=Ecm=500 GeV. The sparticle masses in both plots are mχ~20=mχ~D20=200 GeV and me~L=400 GeV (For the details, see Ref. [1192])
Fig. 137
Fig. 137
Determination of the chargino mixing angles cos2ΦL,R from LC measurements in e+e-χ~1+χ~1- with polarised beams at different cms energies. The electroweak part of the spectrum in this scenario is a modified benchmark scenario SPS1a
Fig. 138
Fig. 138
Forward–backward asymmetry of e- in e+e-χ~1+χ~1-, χ~1-χ~10-ν¯ as a function of mν~ at s=350 GeV and with P(e-)=-90%, P(e+)=+60%. For a nominal value of mν~=1994 GeV the statistical error in the asymmetry is shown [1203]
Fig. 139
Fig. 139
The contours for determination of M1 and M2 in scenario with mχ~1±-mχ~10=770 MeV. The star denotes input values. See Ref. [1223] for more details
Fig. 140
Fig. 140
SUSY mass spectrum consistent with the existing low-energy measurements and the hypothetical LHC measurements at Lint=300fb-1 for the MSSM18 model. The uncertainty ranges represent model dependent uncertainties of the sparticle masses and not direct mass measurements
Fig. 141
Fig. 141
Derived mass distributions of the SUSY particles using low-energy measurements, hypothetical results from LHC with Lint=300fb-1 and hypothetical results from ILC. When comparing to Fig. 140, please note the difference in the scale
Fig. 142
Fig. 142
Evolution of gaugino and sfermion (first and third generation) parameters in the CMSSM for m0=966 GeV, m1/2=800 GeV, A0=0, tanβ=51, signμ=+1[9, 10] to the GUT scale
Fig. 143
Fig. 143
Constraints on the magnitudes of the mixing parameters and possible LFV effects for reference points from [1261]. The shaded areas are those allowed by current limits on BR(τeγ) (dot-dash line) and BR(τμγ) (dash line) using four different reference points (shown by the thick lines bounding the solid shaded areas and the thin blue lines bounding the ruled shaded areas). The solid lines are contours of σ(e+e-τ±μ+2χ0) in fb for s=2000GeV
Fig. 144
Fig. 144
Cross section σ(e+e-χ~1+χ~1-) as a function of the mixing parameter cos2θ13 (a) and cos2θ12 (b) at a LC with cm energy of 500 GeV and polarised beams: PL=-0.9 for electrons and PL=0.6 for positrons. Details of assumed scenarios (a) and (b) are in [1254]
Fig. 145
Fig. 145
Top panel pTmiss dependence of CP asymmetries in neutralino-pair production and decay processes (from [1165]). Bottom panel asymmetries, A1 and A as functions of ΦAt (from [1270])
Fig. 146
Fig. 146
Lightest neutralino χ~10 is mainly higgsino-like: regions in the (λκ)-plane allowed by experimental and phenomenological constraints. The light-blue-shaded regions delimited by the light-blue boundary pass DM constraints. The coloured regions delimited by the purple boundary pass checks within HiggsBounds [1276] and HiggsSignals [1277]. The red area is allowed by all the constraints [1278]
Fig. 147
Fig. 147
Neutralino decay χ~20χ~10+X branching fractions as function of the mass splitting ΔM=Mχ20-Mχ10 (from [1279])
Fig. 148
Fig. 148
Achievable precision on sin2θ23 from BRpV decays of the χ~10 as a function of the produced number of neutralino pairs compared to the current precision from neutrino oscillation measurements. Over a large part of the m1/2 vs. m0 plane, the neutralino-pair production cross section of the order of 100 fb [52]
Fig. 149
Fig. 149
Discovery reach at 95 % CL in Bhabha scattering for the sneutrino mass as a function of λ131 at s=0.5TeV (left panel) and 1 TeV (right panel), for Lint=0.5ab-1. For comparison, the discovery reach on Mν~ in muon pair production for λ232=0.5×Mν~/TeV is also shown (from [1293])
Fig. 150
Fig. 150
Left panel pair production of wino-like neutralinos near threshold in the MSSM and the Dirac theory (from [1192]. Right panel production of the neutral and charged R-Higgs boson pairs at TeV e+e- colliders (from [1178])
Fig. 151
Fig. 151
The (m1/2,m0) plane for tanβ=40 and μ>0, assuming A0=2.5m0,mt=173.2 GeV and mb(mb)SMMS¯=4.25 GeV. Contours and shaded regions are described in the text
Fig. 152
Fig. 152
The (μ,mA) plane for tanβ=30, m1/2=m0=1000 GeV, assuming A0=2.5m0,mt=173.2 GeV and mb(mb)SMMS¯=4.25 GeV. Contours and shaded regions are described in the text
Fig. 153
Fig. 153
Ωh2 as a function of R-1 for mh=120 GeV and ΛR=20 including different processes as specified on the figure. Here ‘1-loop’ stands for one-loop couplings between level 2 and SM particles [1382]
Fig. 154
Fig. 154
Spin-independent DM–nucleon cross section versus DM mass. The upper band (3) corresponds to fermion DM, the middle one (2) to vector DM and the lower one (1) to scalar DM. The solid, dashed and dotted lines represent XENON100 (2012 data [1105]), XENON100 upgrade and XENON1T sensitivities, respectively
Fig. 155
Fig. 155
The (m0,m1/2) planes in the CMSSM including the ATLAS 20/fb jets + /ET, BR(Bs,dμ+μ-), mh, Ωχh2, LUX, and other constraints. The most recent results are indicated by solid lines and filled stars, and previous fit based on 5/fb of LHC data is indicated by dashed lines and open stars. The blue lines denote 68% CL contours, and the red lines denote 95 % CL contours
Fig. 156
Fig. 156
Limits on spin-independent direct detection cross section σSI on protons vs. dark matter mass mDM. In grey the preferred region in the CMSSM, from a combination of [–1443]
Fig. 157
Fig. 157
Spin-independent direct detection cross section σSI on protons vs. dark matter mass mLSP, from [1450]. The black (blue) line are the 90 % CL limits from the XENON100(2011) [1451] and (2012) results [1105]. The dashed brown line is the projected sensitivity of the XENON1T experiment [1452]. The colour code shows the with P>0.2 (red), 0.1<P<0.2 (orange) 0.01<P<0.1 (green) and 0.001<P<0.01 (blue). Note, however, that the relic density constraint is not imposed here

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