Dark Matter Constraints Research Articles

Vector-like technineutron Dark Matter: is a QCD-type Technicolor ruled out by XENON100?

One of the specific predictions of a new strongly coupled dynamics at a TeV scale is the existence of stable vector-like technibaryon states so that the lightest neutral one could serve as a Dark Matter candidate. We study the latter hypothesis in the QCD-type technicolor with \(\mathrm{SU}(3)_\mathrm{TC}\) confined group and one \(\mathrm{SU}(2)_\mathrm{W}\) doublet of vector-like techniquarks consistent with electroweak precision constraints and test it against the existing Dark Matter astrophysics data. We discuss the most stringent Dark Matter constraints on weak interactions of technibaryons in \(\mathrm{SU}(3)_\mathrm{TC}\) technicolor and possible implications of these findings for the cosmological evolution of relic technineutrons. We conclude that vector-like techniquark sectors with an odd group of confinement \(\mathrm{SU}(2n+1)_\mathrm{TC}, n=1,2,\ldots \) and with ordinary vector-like weak \(\mathrm{SU}(2)_\mathrm{W}\) interactions are excluded by XENON100 data under the assumption of technibaryon number conservation in the modern Universe allowing for an even technicolor group \(\mathrm{SU}(2n)_\mathrm{TC}\) only.

Warm and cold fermionic dark matter via freeze-in

The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z2 symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of the model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs.

Detection prospects of singlet fermionic dark matter

A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the Standard Model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both, the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated.

Dark matter and pulsar model constraints from Galactic Center Fermi-LAT gamma-ray observations

Employing Fermi-LAT gamma-ray observations, several independent groups have found excess extended gamma-ray emission at the Galactic Center (GC). Both annihilating dark matter (DM) or a population of $\ensuremath{\sim}{10}^{3}$ unresolved millisecond pulsars (MSPs) are regarded as well-motivated possible explanations. However, there are significant uncertainties in the diffuse galactic background at the GC. We have performed a revaluation of these two models for the extended gamma-ray source at the GC by accounting for the systematic uncertainties of the Galactic diffuse emission model. We also marginalize over point-source and diffuse background parameters in the region of interest. We show that the excess emission is significantly more extended than a point source. We find that the DM (or pulsar-population) signal is larger than the systematic errors and therefore proceed to determine the sectors of parameter space that provide an acceptable fit to the data. We find that a population of 1000--2000 MSPs with parameters consistent with the average spectral shape of Fermi-LAT measured MSPs is able to fit the GC excess emission. For DM, we find that a pure ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ annihilation channel is not a good fit to the data. But a mixture of ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ and $b\overline{b}$ with a $⟨\ensuremath{\sigma}v⟩$ of order the thermal relic value and a DM mass of around 20 to 60 GeV provides an adequate fit.

LHC constraints on light neutralino dark matter in the MSSM

Light neutralino dark matter can be achieved in the Minimal Supersymmetric Standard Model if staus are rather light, with mass around 100 GeV. We perform a detailed analysis of the relevant supersymmetric parameter space, including also the possibility of light selectons and smuons, and of light higgsino- or wino-like charginos. In addition to the latest limits from direct and indirect detection of dark matter, ATLAS and CMS constraints on electroweak-inos and on sleptons are taken into account using a “simplified models” framework. Measurements of the properties of the Higgs boson at 125 GeV, which constrain amongst others the invisible decay of the Higgs boson into a pair of neutralinos, are also implemented in the analysis. We show that viable neutralino dark matter can be achieved for masses as low as 15 GeV. In this case, light charginos close to the LEP bound are required in addition to light right-chiral staus. Significant deviations are observed in the couplings of the 125 GeV Higgs boson. These constitute a promising way to probe the light neutralino dark matter scenario in the next run of the LHC.

Should we still believe in constrained supersymmetry?

We calculate Bayes factors to quantify how the feasibility of the constrained minimal supersymmetric standard model (CMSSM) has changed in the light of a series of observations. This is done in the Bayesian spirit where probability reflects a degree of belief in a proposition and Bayes' theorem tells us how to update it after acquiring new information. Our experimental baseline is the approximate knowledge that was available before LEP, and our comparison model is the Standard Model with a simple dark matter candidate. To quantify the amount by which experiments have altered our relative belief in the CMSSM since the baseline data we compute the Bayes factors that arise from learning in sequence the LEP Higgs constraints, the XENON100 dark matter constraints, the 2011 LHC supersymmetry search results, and the early 2012 LHC Higgs search results. We find that LEP and the LHC strongly shatter our trust in the CMSSM (with $M_0$ and $M_{1/2}$ below 2 TeV), reducing its posterior odds by a factor of approximately two orders of magnitude. This reduction is largely due to substantial Occam factors induced by the LEP and LHC Higgs searches.

Implications of light charginos for Higgs observables, LHC searches and dark matter

A rather high Higgs mass, m_h = 126 GeV, suggests that at least a part of the supersymmetric spectrum of the MSSM may live beyond O(1TeV) and hence inaccessible to the LHC. However, there are theoretical and phenomenological reasons supporting a possibility that charginos and neutralinos remain much closer to the electroweak scale. In this paper, we explore such a scenario in the light of recent Higgs measurements, mainly its di-photon decay rate, where the data might indicate a slight excess over the SM prediction. That excess could be fitted by the contribution of light charginos provided tan(beta) is low to moderate, a possibility that is receiving much attention for other theoretical reasons. We investigate the implications of this scenario for other observables, such as dark matter constraints, electroweak observables and experimental signals at the LHC, like di-lepton, tri-lepton and same-sign dilepton. An important part of the models survive all the constraints and are able to give positive signals at LHC-14TeV and/or XENON1T.

The health of SUSY after the Higgs discovery and the XENON100 data

We analyze the implications for the status and prospects of supersymmetry of the Higgs discovery and the last XENON data. We focus mainly, but not only, on the CMSSM and NUHM models. Using a Bayesian approach we determine the distribution of probability in the parameter space of these scenarios. This shows that, most probably, they are now beyond the LHC reach. This negative chances increase further (at more than 95% c.l.) if one includes dark matter constraints in the analysis, in particular the last XENON100 data. However, the models would be probed completely by XENON1T. The mass of the LSP neutralino gets essentially fixed around 1 TeV. We do not incorporate ad hoc measures of the fine-tuning to penalize unnatural possibilities: such penalization arises automatically from the careful Bayesian analysis itself, and allows to scan the whole parameter space. In this way, we can explain and resolve the apparent discrepancies between the previous results in the literature. Although SUSY has become hard to detect at LHC, this does not necessarily mean that is very fine-tuned. We use Bayesian techniques to show the experimental Higgs mass is at ~ 2 σ off the CMSSM or NUHM expectation. This is substantial but not dramatic. Although the CMSSM or the NUHM are unlikely to show up at the LHC, they are still interesting and plausible models after the Higgs observation; and, if they are true, the chances of discovering them in future dark matter experiments are quite high.

Anomaly mediated supersymmetric models and Higgs data from the LHC

Anomaly mediation models are well motivated supersymmetry breaking scenarios which appear as alternatives to the mSUGRA paradigm. These models are quite compelling from the theoretical point of view and it is therefore important to test if they are also viable models for phenomenology. We perform a study of these models in the light of all standard flavour, collider and dark matter constraints, including also the recent Higgs boson measurements for the mass and signal strengths in the different decay channels. The minimal AMSB scenario can satisfy in part of its parameter space the dark matter requirement but is only marginally consistent with the current Higgs boson mass value. The HyperCharge-AMSB and Mixed Moduli-AMSB scenarios can better describe present data from dark matter, flavour, low energy physics and are consistent with the measured mass of the Higgs boson. The inclusion of the preferred signal strengths for the Higgs boson decay channels shows that for tan(beta) > 5 the HC-AMSB and MM-AMSB models can be consistent with the present Higgs boson data. In contrast the minimal AMSB has a narrower allowed range in tan(beta). These different AMSB scenarios, while consistent with present Higgs boson measurements, can be further tested by future more precise data in the Higgs sector.

Exact Expressions for the Pericenter Precession Caused by Some Dark Matter Distributions and Constraints on Them from Orbital Motions in the Solar System, in the Double Pulsar and in the Galactic Center

We analytically calculate the secular precession of the pericenter of a test particle orbiting a central body surrounded by a continuous distribution of Dark Matter (DM) by using some commonly adopted density profiles for it. We obtain exact expressions without resorting to a-priori simplifying assumptions on the orbital geometry of the test particle. Our formulas allow us to put constraints on the parameters of the DM distributions considered in several local astronomical and astrophysical scenarios, such as the Sun's planetary system, the double pulsar, and the stellar system around the supermassive black hole in Sgr A$^{\ast}$, all characterized by a wide variety of orbital configurations.

ScannerS: constraining the phase diagram of a complex scalar singlet at the LHC

We present the first version of a new tool to scan the parameter space of generic scalar potentials, ScannerS (Coimbra et al., ScannerS project., 2013). The main goal of ScannerS is to help distinguish between different patterns of symmetry breaking for each scalar potential. In this work we use it to investigate the possibility of excluding regions of the phase diagram of several versions of a complex singlet extension of the Standard Model, with future LHC results. We find that if another scalar is found, one can exclude a phase with a dark matter candidate in definite regions of the parameter space, while predicting whether a third scalar to be found must be lighter or heavier. The first version of the code is publicly available and contains various generic core routines for tree level vacuum stability analysis, as well as implementations of collider bounds, dark matter constraints, electroweak precision constraints and tree level unitarity.

Global fits of the cMSSM and NUHM including the LHC Higgs discovery and new XENON100 constraints

We present global fits of the constrained Minimal Supersymmetric Standard Model (cMSSM) and the Non-Universal Higgs Model (NUHM), including the most recent CMS constraint on the Higgs boson mass, 5.8 fb−1 integrated luminosity null Supersymmetry searches by ATLAS, the new LHCb measurement of BR(B̄s → μ+μ−) and the 7-year WMAP dark matter relic abundance determination. We include the latest dark matter constraints from the XENON100 experiment, marginalising over astrophysical and particle physics uncertainties. We present Bayesian posterior and profile likelihood maps of the highest resolution available today, obtained from up to 350M points. We find that the new constraint on the Higgs boson mass has a dramatic impact, ruling out large regions of previously favoured cMSSM and NUHM parameter space. In the cMSSM, light sparticles and predominantly gaugino-like dark matter with a mass of a few hundred GeV are favoured. The NUHM exhibits a strong preference for heavier sparticle masses and a Higgsino-like neutralino with a mass of 1 TeV. The future ton-scale XENON1T direct detection experiment will probe large portions of the currently favoured cMSSM and NUHM parameter space. The LHC operating at 14 TeV collision energy will explore the favoured regions in the cMSSM, while most of the regions favoured in the NUHM will remain inaccessible. Our best-fit points achieve a satisfactory quality-of-fit, with p-values ranging from 0.21 to 0.35, so that none of the two models studied can be presently excluded at any meaningful significance level.

Supersymmetric Higgs bosons beyond the MSSM: An update with flavor and dark matter constraints

Spurred by the discovery of a boson resonance at the LHC as the result of the search for the Standard Model Higgs, we pursue our investigation of the properties and signatures of Higgses in an effective supersymmetric scenario that goes beyond the usual MSSM. Such scenarios were first introduced to alleviate the naturalness problem of the MSSM Higgs and are found to have a very rich phenomenology that allows departures from the Standard Model in the production rate of the Higgs in many of the search channels. We now include the constraints from flavour observables in particular the rare decays b-> s gamma and Bs -> mu+ mu- including the recent measurement from LHCb. We also address the issue of Dark Matter and its impact on Higgs physics. In particular, we incorporate the latest data from XENON100 on the spin independent direct detection rates. These turn out to be powerful constraints, especially if one also imposes that the observed thermal relic density is obtained. We also study models with a low abundance that can more easily evade the direct detection rates. We study the impact of the flavour and Dark Matter observables on the production rates of the Higgs at the LHC, and their correlations in the diphoton, diphoton+jets and 4 leptons. We also comment on the other channels.

Phenomenology of a supersymmetricU(1)B−L×U(1)Rextension of the standard model with inverse seesaw mechanism

We discuss the minimal supersymmetric $U(1{)}_{B\ensuremath{-}L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{R}$ extension of the standard model. Gauge couplings unify as in the minimal supersymmetric standard model (MSSM), even if the scale of $U(1{)}_{B\ensuremath{-}L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{R}$ breaking is as low as order TeV and the model can be embedded into a $SO(10)$ grand unified theory. The phenomenology of the model differs in some important aspects from the MSSM, leading potentially to rich phenomenology at the LHC. It predicts more light Higgs states and the mostly left $CP$-even Higgs having a mass that easily reaches 125 GeV, with no constraints on the supersymmetry spectrum. Right sneutrinos can be the lightest supersymmetric particle, changing all dark matter constraints on supersymmetry parameter space. The model has seven neutralinos, and squark/gluino decay chains involve more complicated cascades than in the MSSM. We also briefly discuss low-energy and accelerator constraints on the model, where the most important limits come from recent ${Z}^{\ensuremath{'}}$ searches at the LHC and upper limits on lepton flavor violation.

Inert doublet dark matter with strong electroweak phase transition

We reconsider the strength of the electroweak phase transition (EWPT) in the inert doublet dark matter model, using a quantitatively accurate form for the one-loop finite temperature effective potential, taking into account relevant particle physics and dark matter constraints, focusing on a standard model Higgs mass near 126 GeV, and doing a full scan of the space of otherwise unconstrained couplings. We find that there is a significant (although fine-tuned) space of parameters for achieving an EWPT sufficiently strong for baryogenesis while satisfying the Xenon100 constraints from direct detection and not exceeding the correct thermal relic density. We predict that the dark matter mass should be in the range 60-67 GeV, and we discuss possible LHC signatures of the charged and CP-odd Higgs bosons, including a 10% decrease of the h -> 2 photon branching ratio.

Dark matter constraints from box-shaped gamma-ray features

The observation of a sharp spectral feature in the gamma-ray sky would be one of the cleanest ways to identify dark matter and pinpoint its properties. Over the years a lot of attention has been paid to two specific features, namely gamma-ray lines and internal bremsstrahlung. Here, we explore a third class of spectral signatures, box-shaped gamma-ray spectra, that naturally arise in dark matter cascade annihilations or decays into intermediate particles that in turn decay into photons. Using Fermi-LAT data, we derive constraints on the dark matter parameter space for both annihilating and decaying dark matter, and show explicitly that our limits are competitive to strategies employing standard spectral features. More importantly, we find robust limits even in the case of non-degenerate dark matter and intermediate particle masses. This result is particularly relevant in constraining dark matter frameworks with gamma-ray data. We conclude by illustrating the power of box-shaped gamma-ray constraints on concrete particle physics scenarios.

Higgs boson in the MSSM in light of the LHC

We investigate the expectations for the light Higgs signal in the MSSM in different search channels at the LHC. After taking into account dark matter and flavor constraints in the MSSM with eleven free parameters, we show that the light Higgs signal in the $gamma\gamma$ channel is expected to be at most at the level of the SM Higgs, while the $h\rightarrow b\bar{b}$ from W fusion and/or the $h \rightarrow\tau\bar\tau$ can be enhanced. For the main discovery mode, we show that a strong suppression of the signal occurs in two different cases: low $M_A$ or large invisible width. A more modest suppression is associated with the effect of light supersymmetric particles. Looking for such modification of the Higgs properties and searching for supersymmetric partners and pseudoscalar Higgs offer two complementary probes of supersymmetry.

Diagnosis of supersymmetry breaking mediation schemes by mass reconstruction at the LHC

If supersymmetry is discovered at the LHC, the next question will be the determination of the underlying model. While this may be challenging or even intractable, a more optimistic question is whether we can understand the main contours of any particular paradigm of the mediation of supersymmetry breaking. The determination of superpartner masses through endpoint measurements of kinematic observables arising from cascade decays is a powerful diagnostic tool. In particular, the determination of the gaugino sector has the potential to discriminate between certain mediation schemes (not all schemes, and not between different UV realizations of a given scheme). We reconstruct gaugino masses, choosing a model where anomaly contributions to supersymmetry breaking are important (KKLT compactification), and find the gaugino unification scale. Moreover, reconstruction of other superpartner masses allows us to solve for the parameters defining the UV model. The analysis is performed in the stop and stau coannihilation regions where the lightest neutralinos are mainly gauginos, to additionally satisfy dark matter constraints. We thus develop observables to determine stau and stop masses to verify that the coannihilation mechanism is indeed operational, and solve for the relic density.

Naturalness, supersymmetry and implications for LHC and dark matter

It is shown that the Hyperbolic Branch of the radiative electroweak symmetry breaking contains in it three regions: the Focal Point, Focal Curves, and Focal Surfaces. Further, the Focal Point is shown to lie on the boundary of a Focal Curve. These focal regions allow for a small μ while scalar masses can become large and may lie in the several TeV region. It is shown that for the mSUGRA model the current LHC-7 constraint depletes the Focal Point region while regions on Focal Curves and Focal Surfaces remain largely intact. The LHC implications for models which lie on Focal Curves are briefly discussed as well as the implications of dark matter constraints for the Focal Point, Focal Curves and Focal Surfaces are discussed.

Light dark matter versus astrophysical constraints

Hints of direct dark matter detection coming from the DAMA, CoGeNT experiments point toward light dark matter with isospin-violating and possibly inelastic couplings. However an array of astrophysical constraints are rapidly closing the window on light dark matter. We point out that if the relic density is determined by annihilation into invisible states, these constraints can be evaded. As an example we present a model of quasi-Dirac dark matter, interacting via two U(1) gauge bosons, one of which couples to baryon number and the other which kinetically mixes with the photon. Annihilation is primarily into “dark neutrinos” that do not mix with the SM, but which could provide an extra component of dark radiation. The model could soon be tested by several experiments searching for such light gauge bosons, and we predict that both could be detected. The model also requires a fourth generation of quarks, whose existence might increase the production cross section of Higgs bosons at the Tevatron and LHC.