Detection Of Neutralino Dark Matter Research Articles

The investigation of dark matter density profiles on the neutralino mass and cross-section annihilation ([formula omitted]) constraint lines of selected galaxy clusters by considering their synchrotron emission

We investigated the indirect detection of neutralino dark matter using radio observation. By looking at the energy spectrum of relativistic positron–electron, this method may provide us with the upper limit of neutralino dark matter emission. Neutralino dark matter can emit synchrotron emissions due to the interaction of relativistic positron–electron spectrum energy with the intracluster magnetic field. The synchrotron emission of dark matter highly depends on the dark matter density at the centre of the cluster. By using the cold dark matter model, the density of dark matter can be obtained using Navarro–Frenk–White (NFW), Einasto, Diemer and Kravtsov 2014 (DK14) and Hernquist profiles. Using the observed radio halo emission as the maximum emission (from dark matter and other sources), we constrained the neutralino mass (mχ) and neutralino cross-section annihilation 〈σv〉 as mχ−〈σv〉 constraint lines. We investigated the effect of different profiles on the mχ−〈σv〉 constraint lines. We also used all the basic annihilation channels for better and stronger constraint lines. Our findings demonstrated the NFW profiles provided us with a good constraint line similarly with previous study. Our results also confirmed that the τ+τ− and tt̄ channels provide us with a stronger constraint at mχ = 100 GeV and 1000 GeV, respectively. Overall, our findings are consistent for the constraint lines of all the chosen galaxy clusters namely A119, A2199, A2142, A2744, A478 and A2029.

Anapole moment of Majorana fermions and implications for direct detection of neutralino dark matter

For Majorana fermions the anapole moment is the only allowed electromagnetic multipole moment. In this work we calculate the anapole moment induced at one-loop by the Yukawa and gauge interactions of a Majorana fermion, using the pinch technique to ensure the finiteness and gauge-invariance of the result. As archetypical example of a Majorana fermion, we calculate the anapole moment for the lightest neutralino in the Minimal Supersymmetric Standard Model, and specifically in the bino, wino and higgsino limits. Finally, we briefly discuss the implications of the anapole moment for the direct detection of dark matter in the form of Majorana fermions.

Stau coannihilation, compressed spectrum, and SUSY discovery potential at the LHC

The lack of observation of supersymmetry thus far implies that the weak supersymmetry scale is larger than what was thought before the LHC era. This observation is strengthened by the Higgs boson mass measurement at $\sim 125$ GeV which within supersymmetric models implies a large loop correction and a weak supersymmetry scale lying in the several TeV region. In addition if neutralino is the dark matter, its relic density puts further constraints on models often requiring coannihilation to reduce the neutralino relic density to be consistent with experimental observation. The coannihilation in turn implies that the mass gap between the LSP and the NLSP will be small leading to softer final states and making the observation of supersymmetry challenging. In this work we investigate stau coannihilation models within supergravity grand unified models and the potential of discovery of such models at the LHC in the post Higgs boson discovery era. We utilize a variety of signal regions to optimize the discovery of supersymmetry in the stau coannihilation region. In the analysis presented we impose the relic density constraint as well as the constraint of the Higgs boson mass. The range of sparticle masses discoverable up to the optimal integrated luminosity of the HL-LHC is investigated. It is found that the mass difference between the stau and the neutralino does not exceed $\sim 20$ GeV over the entire mass range of the models explored. Thus the discovery of a supersymmetric signal arising from the stau coannihilation region will also provide a measurement of the neutralino mass. The direct detection of neutralino dark matter is analyzed within the class of stau coannihilation models investigated. The analysis is extended to include multi-particle coannihilation where stau along with chargino and the second neutralino enter in the stau coannihilation process.

SUSY-QCD corrections for direct detection of neutralino dark matter and correlations with relic density

In this paper, we perform a full next-to-leading order (NLO) QCD calculation of neutralino scattering on protons or neutrons in the MSSM. We match the results of the NLO QCD calculation to the scalar and axial-vector operators in the effective field theory approach. These govern the spin-independent and spin-dependent detection rates, respectively. The calculations have been performed for general bino, wino and higgsino decompositions of neutralino dark matter and required a novel tensor reduction method of loop integrals with vanishing relative velocities and Gram determinants. Numerically, the NLO QCD effects are shown to be of at least of similar size and sometimes larger than the currently estimated nuclear uncertainties. We also demonstrate the interplay of the direct detection rate with the relic density when consistently analyzed with the program $\mathtt{DM@NLO}$.

Prospects for dark matter searches in the pMSSM

We investigate the prospects for detection of neutralino dark matter in the 19-parameter phenomenological MSSM (pMSSM). We explore very wide ranges of the pMSSM parameters but pay particular attention to the higgsino-like neutralino at the ~ 1 TeV scale, which has been shown to be a well motivated solution in many constrained supersymmetric models, as well as to a wino-dominated solution with the mass in the range of 2-3 TeV. After summarising the present bounds on the parameter space from direct and indirect detection experiments, we focus on prospects for detection of the Cherenkov Telescope Array (CTA). To this end, we derive a realistic assessment of the sensitivity of CTA to photon fluxes from dark matter annihilation by means of a binned likelihood analysis for the Einasto and Navarro-Frenk-White halo profiles. We use the most up to date instrument response functions and background simulation model provided by the CTA Collaboration. We find that, with 500 hours of observation, under the Einasto profile CTA is bound to exclude at the 95% C.L. almost all of the ~ 1 TeV higgsino region of the pMSSM, effectively closing the window for heavy supersymmetric dark matter in many realistic models. CTA will be able to probe the vast majority of cases corresponding to a spin-independent scattering cross section below the reach of 1-tonne underground detector searches for dark matter, in fact even well below the irreducible neutrino background for direct detection. On the other hand, many points lying beyond the sensitivity of CTA will be within the reach of 1-tonne detectors, and some within collider reach. Altogether, CTA will provide a highly sensitive way of searching for dark matter that will be partially overlapping and partially complementary with 1-tonne detector and collider searches, thus being instrumental to effectively explore the nearly full parameter space of the pMSSM.

Evolution of dark matter halos and their radio emissions

Radio synchrotron emission is expected as a natural by-product of the self-annihilation of super-symmetric dark matter particles. In this work we discuss the general properties of the radio emission expected in a wide range of dark matter halos, from local dwarf spheroidal galaxies to large and distant galaxy clusters with the aim to determine the neutralino dark matter detection prospects of the Square Kilometre Array (SKA). The analysis of the SKA detection of dark matter(DM)-induced radio emission is presented for structures spanning a wide range of masses and redshifts, and we also analyze the limits that the SKA can set on the thermally averaged neutralino annihilation cross-section in the event of non-detection. To this aim, we construct a model of the redshift evolution of the radio emissions of dark matter halos and apply it to generate predicted fluxes from a range of neutralino masses and annihilation channels for the dark matter halos surrounding dwarf galaxies, galaxies and galaxy clusters. Using the available SKA performance predictions and its ability to determine an independent measure of the magnetic field in cosmic structures, we explore both the detailed detection prospects and the upper-bounds that might be placed on the neutralino annihilation cross-section in the event of non-detection. We find that the SKA can access a neutralino parameter space far larger than that of any preceding indirect-detection experiment, also improving on the realistic CTA detection prospects, with the possibility of setting cross-section upper-bounds up to four orders of magnitude below the thermal relic density bound. Additionally, we find that neutralino radio emissions carry redshift-independent signatures of the dominant annihilation channel and of neutralino mass, offering therefore a means to identify such non-thermal emissions within the observing frequency range of the SKA.

Direct and indirect detection of neutralino dark matter and collider signatures in anSO(10)model with two intermediate scales

We investigate the detectability of neutralino dark matter via direct and indirect searches as well as collider signatures of an $SO(10)$ model with two intermediate scales. We compare the direct dark matter detection cross section and the muon flux due to neutralino annihilation in the Sun that we obtain in this model with minimal supergravity predictions and with the sensitivity of current and future experiments. In both cases, we find that the detectability improves as the model deviates more from minimal supergravity. In order to study collider signatures, we choose two benchmark points that represent the main phenomenological features of the model: a lower value of $|\ensuremath{\mu}|$ and reduced third-generation sfermion masses due to extra Yukawa coupling contributions in the renormalization group equations and increased first- and second-generation slepton masses due to new gaugino loop contributions. We show that measurements at the LHC can distinguish this model from minimal supergravity in both cases, by counting events containing leptonically decaying ${Z}^{0}$ bosons, heavy neutral Higgs bosons, or like-sign lepton pairs. The methods we develop can be used more generally to characterize models of weak-scale supersymmetry.

Connecting the direct detection of dark matter with observation of sparticles at the LHC

An analysis is given connecting event rates for the direct detection of neutralino dark matter with the possible signatures of supersymmetry at the LHC. It is shown that if an effect is seen in the direct detection experiments at a level of $O(10^{-44})$ cm$^2$ for the neutralino-proton cross section, then within the mSUGRA model the next heavier particle above the neutralino is either a stau, a chargino, or a CP odd/CP even (A/H) Higgs boson. Further, the collider analysis shows that models with a neutralino-proton cross section at the level of $(1-5)\times 10^{-44}$ cm$^2$ could be probed with as little as 1 fb$^{-1}$ of integrated luminosity at the LHC at $\sqrt s=10$ TeV. The most recent limit from the five tower CDMS II result on WIMP-nucleon cross section is discussed in this context. It is argued that the conclusions of the analysis given here are more broadly applicable with inclusion of non-universalities in the SUGRA models.

Update on the direct detection of dark matter in MSSM models with non-universal Higgs masses

We discuss the possibilities for the direct detection of neutralino dark matter via elastic scattering in variants of the minimal supersymmetric extension of the Standard Model (MSSM) with non-universal supersymmetry-breaking contributions to the Higgs masses, which may be either equal (NUHM1) or independent (NUHM2). We compare the ranges found in the NUHM1 and NUHM2 with that found in the MSSM with universal supersymmetry-breaking contributions to all scalar masses, the CMSSM. We find that both the NUHM1 and NUHM2 offer the possibility of larger spin-independent dark matter scattering cross sections than in the CMSSM for larger neutralino masses, since they allow the density of heavier neutralinos with large Higgsino components to fall within the allowed range by astrophysics. The NUHM1 and NUHM2 also offer more possibilities than the CMSSM for small cross sections for lower neutralino masses, since they may be suppressed by scalar and pseudoscalar Higgs masses that are larger than in the CMSSM.

Panglossian prospects for detecting neutralino dark matter in light of natural priors?

In most global fits of the constrained minimal supersymmetric model (CMSSM) to indirect data, the a priori likelihoods of any two points in tan β are treated as equal, and the more fundamental μ and B Higgs potential parameters are fixed by potential minimization conditions. We find that, if instead a flat (``natural'') prior measure on μ and B is placed, a strong preference exists for the focus point region from fits to particle physics and cosmological data. In particular, we find that the lightest neutralino is strongly favored to be a mixed bino-higgsino ( ~ 10% higgsino). Such mixed neutralinos have large elastic scattering cross sections with nuclei, leading to extremely promising prospects for both underground direct detection experiments and neutrino telescopes. In particular, the majority of the posterior probability distribution falls within parameter space within an order of magnitude of current direct detection constraints. Furthermore, neutralino annihilations in the sun are predicted to generate thousands of neutrino induced muon events per years at IceCube. Thus, assuming the framework of the CMSSM and using the natural prior measure, modulo caveats regarding astrophysical uncertainties, we are likely to be living in a world with good prospects for the direct and indirect detection of neutralino dark matter. These conclusions have a dependence upon the prior measure, which more data will reduce.

Collider signals and neutralino dark matter detection in relic-density-consistent models without universality

We present brief synopses of supersymmetric models where either the neutralino composition or its mass is adjusted so that thermal relic neutralinos from the Big Bang saturate the measured abundance of cold dark matter in the universe. We first review minimal supergravity (mSUGRA), and then examine its various one-parameter extensions where we relax the assumed universality of the soft supersymmetry breaking parameters. Our goal is to correlate relic-density-allowed parameter choices with expected phenomena in direct, indirect and collider dark matter search experiments. For every non-universal model, we first provide plots to facilitate the selection of ``dark-matter allowed'' parameter space points, and then present salient features of each model with respect to searches at Tevatron, LHC and ILC and also direct and indirect dark matter searches. We present benchmark scenarios that allow one to compare and contrast the non-universal models with one another and with the paradigm mSUGRA framework. We show that many implications about sparticle properties and collider signals drawn from the analysis of the relic density constraint within mSUGRA do not carry over to simple one-parameter extensions of the mSUGRA framework. We find that in many relic-density-consistent models, there is one (or more) detectable edge in the invariant mass distribution of same-flavour, opposite sign dileptons in SUSY cascade decay events at the LHC. Finally, we scan the parameter space of these various models, requiring consistency with the LEP2 constraint on the chargino mass, and with the observed relic density, and examine prospects for direct and indirect dark matter detection. We find that in a large number of cases the mechanism that causes the early universe neutralino annihilation rate to be large (so as to produce the measured relic density) also enhances the direct detection rate, and often also the rates for indirect detection of neutralino dark matter.

Prospects for the direct detection of neutralino dark matter in orbifold scenarios

We analyse the phenomenology of orbifold scenarios from the heterotic superstring, and the resulting theoretical predictions for the direct detection of neutralino dark matter. In particular, we study the parameter space of these constructions, computing the low-energy spectrum and taking into account the most recent experimental and astrophysical constraints, as well as imposing the absence of dangerous charge and colour breaking minima. In the remaining allowed regions the spin-independent part of the neutralino-proton cross section is calculated and compared with the sensitivity of dark matter detectors. In addition to the usual non universalities of the soft terms in orbifold scenarios due to the modular weight dependence, we also consider D-term contributions to scalar masses. These are generated by the presence of an anomalous U(1), providing more flexibility in the resulting soft terms, and are crucial in order to avoid charge and colour breaking minima. Thanks to the D-term contribution, large neutralino detection cross sections can be found, within the reach of projected dark matter detectors.

Probing Supersymmetric Parameters With Astrophysical Observations

A wide range of techniques have been developed to search for particle dark matter, including direct detection, indirect detection, and collider searches. The prospects for the detection of neutralino dark matter is quite promising for each of these three very different methods. Looking ahead to a time in which these techniques have successfully detected neutralino dark matter, we explore the ability of these observations to determine the parameters of supersymmetry. In particular, we focus on the ability of direct and indirect detection techniques to measure the parameters $\mu$ and $m_A$. We find that $\mu$ can be much more tightly constrained if astrophysical measurements are considered than by LHC data alone. In supersymmetric models within the $A$-funnel region of parameter space, we find that astrophysical measurements can determine $m_A$ to roughly $\pm100$ GeV precision.

Mixed higgsino dark matter from a large SU(2) gaugino mass

We observe that in SUSY models with non-universal GUT scale gaugino mass parameters, raising the GUT scale SU(2) gaugino mass |M2| from its unified value results in a smaller value of ?mHu2 at the weak scale. By the electroweak symmetry breaking conditions, this implies a reduced value of ?2 vis ? vis models with gaugino mass unification. The lightest neutralino can then be mixed Higgsino dark matter with a relic density in agreement with the measured abundance of cold dark matter (DM). We explore the phenomenology of this high |M2| DM model. The spectrum is characterized by a very large wino mass and a concomitantly large splitting between left- and right- sfermion masses. In addition, the lighter chargino and three light neutralinos are relatively light with substantial higgsino components. The higgsino content of the LSP implies large rates for direct detection of neutralino dark matter, and enhanced rates for its indirect detection relative to mSUGRA. We find that experiments at the LHC should be able to discover SUSY over the portion of parameter space where m 2350?2750 GeV, depending on the squark mass, while a 1 TeV electron-positron collider has a reach comparable to that of the LHC. The dilepton mass spectrum in multi-jet + ?+??+ETmiss events at the LHC will likely show more than one mass edge, while its shape should provide indirect evidence for the large higgsino content of the decaying neutralinos.

Direct detection of neutralino dark matter in nonstandard cosmologies

We compute the neutralino direct detection rate in nonstandard cosmological scenarios where neutralinos account for the dark matter of the Universe. Significant differences are found when such rates are compared with those predicted by the standard cosmological model. For b-ino-like neutralinos, the main feature is the presence of additional light (m Χ ≤ 40 GeV) and heavy (m Χ ≥ 600 GeV) neutralinos with detection rates within the sensitivity of future dark matter experiments. For Higgsino-like and W-ino-like neutralinos lighter than m Χ ∼ 1 TeV, enhancements of more than 2 orders of magnitude in the largest detection rates are observed. Thus, if dark matter is made up of neutralinos, the prospects for their direct detection are in general more promising than in the standard cosmology.

Neutralino dark matter in the NMSSM

We analyse the direct detection of neutralino dark matter in the framework of the next-to-minimal supersymmetric standard model. Taking into account all the available constraints from LEPII and Tevatron, including bounds from the muon anomalous magnetic moment and flavour constraint as b → sγ, we compute the neutralino–nucleon cross section and compare the results with the sensitivity of dark matter detectors. We also study the relic abundance of neutralinos, comparing it with WMAP observations. We show that a light singlet-like Higgs can escape accelerator constraints allowing for scenarios with large cross sections and a very interesting phenomenology.

Interplay between collider searches for supersymmetric Higgs bosons and direct dark matter experiments

In this article, we explore the interplay between searches for supersymmetric particles and Higgs bosons at hadron colliders (the Tevatron and the LHC) and direct dark matter searches (such as CDMS, ZEPLIN, XENON, EDELWEISS, CRESST, WARP and others). We focus on collider searches for heavy MSSM Higgs bosons $(A,H,{H}^{\ifmmode\pm\else\textpm\fi{}})$ and how the prospects for these searches are impacted by direct dark matter limits and vice versa. We find that the prospects of these two experimental programs are highly interrelated. A positive detection of $A$, $H$ or ${H}^{\ifmmode\pm\else\textpm\fi{}}$ at the Tevatron would dramatically enhance the prospects for a near future direct discovery of neutralino dark matter. Similarly, a positive direct detection of neutralino dark matter would enhance the prospects of discovering heavy MSSM Higgs bosons at the Tevatron or the LHC. Combining the information obtained from both types of experimental searches will enable us to learn more about the nature of supersymmetry.

Indirect detection of light neutralino dark matter in the next-to-minimal supersymmetric standard model

We explore the prospects for indirect detection of neutralino dark matter in supersymmetric models with an extended Higgs sector (next-to-minimal supersymmetric standard model, or NMSSM). We compute, for the first time, one-loop amplitudes for NMSSM neutralino pair annihilation into two photons and two gluons, and point out that extra diagrams (with respect to the minimal supersymmetric standard model, or MSSM), featuring a potentially light $CP$-odd Higgs boson exchange, can strongly enhance these radiative modes. Expected signals in neutrino telescopes due to the annihilation of relic neutralinos in the Sun and in the Earth are evaluated, as well as the prospects of detection of a neutralino annihilation signal in space-based gamma-ray, antiproton and positron search experiments, and at low-energy antideuteron searches. We find that in the low mass regime the signals from capture in the Earth are enhanced compared to the MSSM, and that NMSSM neutralinos have a remote possibility of affecting solar dynamics. Also, antimatter experiments are an excellent probe of galactic NMSSM dark matter. We also find enhanced two-photon decay modes that make the possibility of the detection of a monochromatic gamma-ray line within the NMSSM more promising than in the MSSM, although likely below the sensitivity of next generation gamma-ray telescopes.

GLAST versus PAMELA: a comparison between the detection of gamma rays andpositrons from neutralino annihilation

We study the indirect detection of neutralino dark matter using positrons and gammarays from its annihilation in the galactic halo. Considering the HESS data as thespectrum constituting the gamma ray background, we compare the prospects for theexperiments GLAST and PAMELA in a general supergravity framework withnon-universal scalar and gaugino masses. We show that with a boost factor of about10, PAMELA will be competitive with GLAST for typical NFW cuspy profiles.

Collider and dark matter searches in models with mixed modulus-anomaly mediated SUSY breaking

We investigate the phenomenology of supersymmetric models where moduli fields and the Weyl anomaly make comparable contributions to SUSY breaking effects in the observable sector of fields. This mixed modulus-anomaly mediated supersymmetry breaking (MM-AMSB) scenario is inspired by models of string compactification with fluxes, which have been shown to yield a de Sitter vacuum (as in the recent construction by Kachru {\it et al}). The phenomenology depends on the so-called modular weights which, in turn, depend on the location of various fields in the extra dimensions. We find that the model with zero modular weights gives mass spectra characterized by very light top squarks and/or tau sleptons, or where M_1\sim -M_2 so that the bino and wino are approximately degenerate. The top squark mass can be in the range required by successful electroweak baryogenesis. The measured relic density of cold dark matter can be obtained via top squark co-annihilation at low \tan\beta, tau slepton co-annihilation at large \tan\beta or via bino-wino coannihilation. Then, we typically find low rates for direct and indirect detection of neutralino dark matter. However, essentially all the WMAP-allowed parameter space can be probed by experiments at the CERN LHC, while significant portions may also be explored at an e^+e^- collider with \sqrt{s}=0.5--1 TeV. We also investigate a case with non-zero modular weights. In this case, co-annihilation, A-funnel annihilation and bulk annihilation of neutralinos are all allowed. Results for future colliders are qualitatively similar, but prospects for indirect dark matter searches via gamma rays and anti-particles are somewhat better.