Spin-independent Direct Detection Cross Section Research Articles

Scalar electroweak multiplet dark matter

We revisit the theory and phenomenology of scalar electroweak multiplet thermal dark matter. We derive the most general, renormalizable scalar potential, assuming the presence of the Standard Model Higgs doublet, H, and an electroweak multiplet Φ of arbitrary SU(2)L rank and hypercharge, Y. We show that, in general, the Φ-H Higgs portal interactions depend on three, rather than two independent couplings as has been previously considered in the literature. For the phenomenologically viable case of Y = 0 multiplets, we focus on the septuplet and quintuplet cases, and consider the interplay of relic density and spin-independent direct detection cross section. We show that both the relic density and direct detection cross sections depend on a single linear combination of Higgs portal couplings, λeff. For λeff ∼ mathcal{O} (1), present direct detection exclusion limits imply that the neutral component of a scalar electroweak multiplet would comprise a subdominant fraction of the observed DM relic density.

How light a higgsino or a wino dark matter can become in a compressed scenario of MSSM

Higgsinos and Wino have strong motivations for being Dark Matter (DM) candidates in supersymmetry, but their annihilation cross sections are quite large. For thermal generation and a single component DM setup the higgsinos or wino may have masses of around 1 or 2-3 TeV respectively. For such DM candidates, a small amount of slepton coannihilation may decrease the effective DM annihilation cross section. This, in turn reduces the lower limit of the relic density satisfied DM mass by more than 50%. Almost a similar degree of reduction of the same limit is also seen for squark coannihilations. However, on the contrary, for near degeneracy of squarks and higgsino DM, near its generic upper limit, the associated coannihilations may decrease the relic density, thus extending the upper limit towards higher DM masses. We also compute the direct and indirect detection signals. Here, because of the quasi-mass degeneracy of the squarks and the LSP, we come across a situation where squark exchange diagrams may contribute significantly or more strongly than the Higgs exchange contributions in the spin-independent direct detection cross section of DM. For the higgsino-DM scenario, we observe that a DM mass of 600 GeV to be consistent with WMAP/PLANCK and LUX data for sfermion coannihilations. The LUX data itself excludes the region of 450 to 600 GeV, by a half order of magnitude of the cross-section, well below the associated uncertainty. The similar combined lower limit for a wino DM is about 1.1 TeV. There is hardly any collider bound from the LHC for squarks and sleptons in such a compressed scenario where sfermion masses are close to the mass of a higgsino/wino LSP.

Is the dark matter particle its own antiparticle?

We propose a test based on direct detection data that allows to determine if the dark matter particle is different from its antiparticle. The test requires the precise measurement of the dark matter spin-independent direct detection cross sections off $\mathrm{three}$ different nuclei, and consists of interpreting such signals in terms of self-conjugate (particle $=$ antiparticle) dark matter to see if such interpretation is consistent. If it is not, the dark matter must be different from its antiparticle. We illustrate this procedure for two sets of target nuclei, $\mathrm{\{Xe, Ar, Si\}}$ and $\mathrm{\{Xe, Ar, Ge\}}$, identifying the regions of the parameter space where it is particularly feasible. Our results indicate that future signals in direct detection experiments, if sufficiently accurate, might be used to establish that the dark matter particle is not its own antiparticle --a major step towards the determination of the fundamental nature of the dark matter.

Present status and future tests of the higgsino-singlino sector in the NMSSM

The light higgsino-singlino scenario of the NMSSM allows to combine a naturally small μ parameter with a good dark matter relic density. Given the new constraints on spin-dependent and spin-independent direct detection cross sections in 2016 we study first which regions in the plane of chargino- and LSP-masses below 300 GeV remain viable. Subsequently we investigate the impact of searches for charginos and neutralinos at the LHC, and find that the limits from run I do not rule out any additional region in this plane. Only the HL-LHC at 3000 fb−1 will test parts of this plane corresponding to higgsino-like charginos heavier than 150 GeV and relatively light singlinos, but notably the most natural regions with lighter charginos seem to remain unexplored.

Light Higgsino dark matter in the MSSM on D-branes

When supersymmetry (SUSY) breaking is dominated by the complex structure moduli and the universal dilaton, a subset of the SUSY parameter space in a realistic minimal supersymmetric standard model constructed from intersecting/magnetized D-branes are universal, similar to the effective minimal supergravity (mSUGRA)/constrained minimal supersymmetric standard model (CMSSM) parameter space with a universal scalar mass m0, a universal gaugino mass and with the universal trilinear term fixed to be minus the gaugino mass, A0 = −m1/2. More generally, the scalar mass-squared terms for sfermions are split about the Higgs mass-squared terms, and , for generic values of the Kähler moduli. The scalar masses are universal only for a specific choice of the Kähler moduli. The hyperbolic branch/focus point (HB/FP) regions of this parameter space are present for both and . Interestingly, it is known that FPs may be realized with any boundary condition of the form with x an arbitrary constant, the same form as those in this model. Thus, we should expect to obtain the same set of FPs in the model regardless of the choice of Kähler moduli. It should be emphasized that the more general choice of Kähler moduli goes beyond (mSUGRA/CMSSM). It is shown that there exists superpartner spectra with a light Higgsino-like LSP with 230–350 GeV and a Higgs mass in the range 124–126 GeV, and which satisfy most standard experimental constraints. Consequently, viable spectra with low electroweak fine-tuning between 3%–7% may be obtained. The spin-independent direct-detection crosssections are in range of future experiments such as XENON−1 T and super CDMS, while the relic density is smaller than the WMAP and Planck bounds by roughly a factor of ten, implying that the LSP is sub-dominant component of dark matter. In addition, most of the spectra are consistent with constraints from indirect-detection experiments.

Self-interacting scalar dark matter with local Z3 symmetry

We construct a self-interacting scalar dark matter (DM) model with local discrete Z3 symmetry that stabilizes a weak scale scalar dark matter X. The model assumes a hidden sector with a local U(1)X dark gauge symmetry, which is broken spontaneously into Z3 subgroup by nonzero VEV of dark Higgs field ϕX (⟨ϕX⟩≠0). Compared with global Z3 DM models, the local Z3 model has two new extra fields: a dark gauge field Z′ and a dark Higgs field ϕ (a remnant of the U(1)X breaking). After imposing various constraints including the upper bounds on the spin-independent direct detection cross section and thermal relic density, we find that the scalar DM with mass less than 125 GeV is allowed in the local Z3 model, in contrary to the global Z3 model. This is due to new channels in the DM pair annihilations open into Z′ and ϕ in the local Z3 model. Most parts of the newly open DM mass region can be probed by XENON1T and other similar future experiments. Also if ϕ is light enough (a few MeV ≲mϕ≲ O(100) MeV), it can generate a right size of DM self-interaction and explain the astrophysical small scale structure anomalies. This would lead to exotic decays of Higgs boson into a pair of dark Higgs bosons, which could be tested at LHC and ILC.

130 GeV gamma ray line and enhanced Higgs di-photon rate from Triplet-Singlet extended MSSM

We propose an economic extension of minimal supersymmetric standard model with a SU(2) singlet and Y=0 triplet, which can explain (i) the 125 GeV Higgs boson without fine tuning, (ii) the 130 GeV $\gamma$-ray line seen at Fermi-LAT, (as well as a second photon line at 114 GeV)(iii) an enhanced Higgs di-photon decay rate seen by ATLAS, while being consistent with dark matter relic density and recent XENON 100 exclusion limits on spin-independent direct detection cross-section. We obtain the required cross-section of $10^{-27}cm^3s^{-1}$ for the 130 GeV $\gamma$-ray flux through the resonant annihilation of dark matter via pseudoscalar triplet Higgs of mass $\sim$260 GeV. The dark matter is predominantly bino-higgsino which has large couplings with photons (through higgsino) and gives correct relic density (through bino). We get the enhanced Higgs diphoton decay rate, $R_{\gamma \gamma}\simeq 1.24$ dominantly contributed by the light chargino-loops, which can account for the reported excess seen in the $h\rightarrow \gamma \gamma$ channel by ATLAS.

Naturalness of light neutralino dark matter in pMSSM after LHC, XENON100 and Planck data

Abstract We examine the possibility of a light (below 46 GeV) neutralino dark matter (DM) candidate within the 19-parameter phenomenological Minimal Supersymmetric Standard Model (pMSSM) in the light of various recent experimental results, especially from the LHC, XENON100, and Planck. We also study the extent of electroweak fine-tuning for such a light neutralino scenario in view of the null results from the searches for supersymmetry so far. Using a Markov Chain Monte Carlo likelihood analysis of the full pMSSM parameter space, we find that a neutralino DM with mass ≳ 10 GeV can in principle still satisfy all the existing constraints. Our light neutralino solutions can be broadly divided into two regions: (i) The solutions in the 10–30 GeV neutralino mass range are highly fine-tuned and require the existence of light selectrons (below 100 GeV) in order to satisfy the observed DM relic density. We note that these are not yet conclusively ruled out by the existing LEP/LHC results, and a dedicated analysis valid for a non-unified gaugino mass spectrum is required to exclude this possibility. (ii) The solutions with low fine-tuning are mainly in the 30–46 GeV neutralino mass range. However, a major portion of it is already ruled out by the latest XENON100 upper limits on its spin-independent direct detection cross section, and the rest of the allowed points are within the XENON1T projected limit. Thus, we show that the allowed MSSM parameter space for a light neutralino DM below the LEP limit of 46 GeV, possible in supersymmetric models without gaugino mass unification, could be completely accessible in near future. This might be useful in view of the recent claims for positive hints of a DM signal in some direct detection experiments.

Electroweak corrections to the direct detection cross section of inert Higgs dark matter

The inert higgs model is a minimal extension of the Standard Model that features a viable dark matter candidate, the so-called inert higgs ($H^0$). In this paper, we compute and analyze the dominant electroweak corrections to the direct detection cross section of dark matter within this model. These corrections arise from one-loop diagrams mediated by gauge bosons that, contrary to the tree-level result, do not depend on the unknown scalar coupling $\lambda$. We study in detail these contributions and show that they can modify in a significant way the prediction of the spin-independent direct detection cross section. In both viable regimes of the model, $\mh<M_W$ and $\mh\gtrsim 500 \gev$, we find regions where the cross section at one-loop is much larger than at tree-level. We also demonstrate that, over the entire viable parameter space of this model, these new contributions bring the spin-independent cross section within the reach of future direct detection experiments.

Next-to-minimal supersymmetric model Higgs scenarios for partially universal GUT scale boundary conditions

We examine the extent to which it is possible to realize the NMSSM ``ideal Higgs'' models espoused in several papers by Gunion et al. in the context of partially universal GUT scale boundary conditions. To this end we use the powerful methodology of nested sampling. We pay particular attention to whether ideal-Higgs-like points not only pass LEP constraints but are also acceptable in terms of the numerous constraints now available, including those from the Tevatron and $B$-factory data, $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ and the relic density $\ensuremath{\Omega}{h}^{2}$. In general for this particular methodology and range of parameters chosen, very few points corresponding to said previous studies were found, and those that were found were at best $2\ensuremath{\sigma}$ away from the preferred relic density value. Instead, there exist a class of points, which combine a mostly singlet-like Higgs with a mostly singlino-like neutralino coannihilating with the lightest stau, that are able to effectively pass all implemented constraints in the region $80&lt;{m}_{h}&lt;100$. It seems that the spin-independent direct detection cross section acts as a key discriminator between ideal Higgs points and the hard to detect singlino-like points.

Implications of Dark Matter direct detection results on LHC physics

The requirements of electroweak symmetry breaking (EWSB) and correct thermal relic density of Dark Matter (DM) predict large DM spin-independent direct detection cross section in scalar DM models based on SO(10) non-supersymmetric GUTs. Assuming that the two signal-like events recently observed by CDMS II experiment actually are DM particle recoils on nuclei, we study implications of this assumption on EWSB, on the Higgs boson mass and on direct production of scalar DM at LHC experiments. In our scenario this assumption indicates relatively light DM, MDM∼O(80) GeV, implying large DM pair production cross section at LHC in correlation with the spin-independent direct DM detection cross section. Most importantly, the next-to-lightest dark scalar SNL is predicted to be long-lived, providing distinctive experimental signatures of displaced vertex of two leptons or jets plus missing transverse energy.

Electroweak Symmetry Breaking from the Soft Portal into Dark Matter and Prediction for Direct Detection

Scalar dark matter (DM) can have dimensionful coupling to the Higgs boson-the soft portal into DM-which is predicted to be unsuppressed by the underlying SO(10) grand unified theory (GUT). The dimensionful coupling can be large, μ/v>>1, without spoiling the perturbativity of low energy theory up to the GUT scale. We show that the soft portal into DM naturally triggers radiative electroweak symmetry breaking (EWSB) via large 1-loop DM corrections to the effective potential. In this scenario, EWSB, the DM thermal freeze-out cross section, and DM scattering on nuclei are all dominated by the same coupling, predicting the DM mass range to be 700 GeV<M(DM)<2 TeV. The spin-independent direct detection cross section is predicted to be just below the present experimental bounds.

Dark matter as the signal of grand unification

We argue that the existence of dark matter (DM) is a possible consequence of grand unification (GUT) symmetry breaking. In GUTs like $SO(10)$, discrete ${Z}_{2}$ matter parity $(\ensuremath{-}1{)}^{3(B\ensuremath{-}L)}$ survives despite broken $B\ensuremath{-}L$, and group theory uniquely determines that the only possible ${Z}_{2}$-odd matter multiplets belong to representation $\mathbf{16}$. We construct the minimal nonsupersymmetric $SO(10)$ model containing one scalar $\mathbf{16}$ for DM and study its predictions below ${M}_{G}$. We find that electroweak symmetry breaking occurs radiatively due to DM couplings to the standard model Higgs boson. For thermal relic DM the mass range ${M}_{\mathrm{DM}}\ensuremath{\sim}\mathcal{O}(0.1--1)\text{ }\text{ }\mathrm{TeV}$ is predicted by model perturbativity up to ${M}_{G}$. For ${M}_{\mathrm{DM}}\ensuremath{\sim}\mathcal{O}(1)\text{ }\text{ }\mathrm{TeV}$ to explain the observed cosmic ray anomalies with DM decays, there exists a lower bound on the spin-independent direct detection cross section within the reach of planned experiments.

Connection between a Possible Fifth Force and the Direct Detection of Dark Matter

If there were a fifth force in the dark sector and dark matter (DM) particles interacted nongravitationally with ordinary matter, quantum corrections generically would lead to a fifth force in the visible sector. We show how the strong experimental limits on fifth forces in the visible sector produce bounds on the cross section for DM detection and the strength of the fifth force in the dark sector. For a fifth force comparable in strength to gravity, the spin-independent direct detection cross section must typically be less, similar10;{-55} cm;{2}. The anomalous acceleration of ordinary matter falling towards dark matter would also be constrained: eta_{OM-DM} less, similar10;{-8}.