Dark matter from a complex scalar singlet: the role of dark CP and other discrete symmetries
TL;DR: In this article, the authors study the case of a pseudo-scalar dark matter candidate which emerges from a complex scalar singlet, charged under a global U(1) symmetry, which is broken both explicitly and spontaneously.
Abstract: We study the case of a pseudo-scalar dark matter candidate which emerges from a complex scalar singlet, charged under a global U(1) symmetry, which is broken both explicitly and spontaneously. The pseudo-scalar is naturally stabilized by the presence of a remnant discrete symmetry: dark CP. We study and compare the phenomenology of several simplified models with only one explicit symmetry breaking term. We find that several regions of the parameter space are able to reproduce the observed dark matter abundance while respecting direct detection and invisible Higgs decay limits: in the resonances of the two scalars, featuring the known as forbidden or secluded dark matter, and through non-resonant Higgs-mediated annihilations. In some cases, combining different measurements would allow one to distinguish the breaking pattern of the symmetry. Moreover, this setup admits a light DM candidate at the sub-GeV scale. We also discuss the situation where more than one symmetry breaking term is present. In that case, the dark CP symmetry may be spontaneously broken, thus spoiling the stability of the dark matter candidate. Requiring that this does not happen imposes a constraint on the allowed parameter space. Finally, we consider an effective field theory approach valid in the pseudo-Nambu-Goldstone boson limit and when the U(1) breaking scale is much larger than the electroweak scale.
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TL;DR: In this paper , the cancellation mechanism in the U(1) symmetric pseudo-Nambu-Goldstone-Boson Dark Matter (pNGB DM) model was studied from a multi-angle perspective.
Abstract: A bstract We present two alternative proofs for the cancellation mechanism in the U(1) symmetric pseudo-Nambu-Goldstone-Boson Dark Matter (pNGB DM) model. They help us to have a better understanding of the mechanism from multi-angle, and inspire us to propose some interesting generalizations. In the first proof, we revisit the non-linear representation method and rephrase the argument with the interaction eigenstates. In this picture, the phase mode (DM) can only have a trilinear interaction with a derivative-squared acting on the radial mode when the DM is on-shell. Thus, the DM-quark scattering generated by a mass mixing between the radial mode and the Higgs boson vanishes in the limit of zero-momentum transfer. Using the same method, we can easily generalize the model to an SO(N) model with general soft-breaking structures. In particular, we study the soft-breaking cubic terms and identify those terms which preserve the cancellation mechanism for the DM candidate. In our discussion of the second method, we find that the cancellation relies on the special structure of mass terms and interactions of the mediators. This condition can be straightforwardly generalized to the vector-portal models. We provide two examples of the vector-portal case where the first one is an SU(2) L × U(1) Y × U(1) X model and the second one is an SU(2) L × U(1) Y × U(1) B−L × U(1) X model. In the first model the vector mediators are the Z μ boson and a new U(1) X gauge boson X ν , while in the second model the mediators are the U(1) B−L and U(1) X gauge bosons. The cancellation mechanism works in both models when there are no generic kinetic mixing terms for the gauge bosons. Once the generic kinetic mixing terms are included, the first model requires a fine-tuning of the mixing parameter to avoid the stringent direct detection bound, while the second model can naturally circumvent it.
7 citations
TL;DR: In this article , a model of the pseudo-Nambu-Goldstone (pNG) dark matter (DM) was proposed, and a soft symmetry breaking term that breaks the SU(2)g global symmetry into the U(1)g globally symmetric global symmetry explicitly was determined.
Abstract:
A model of the pseudo-Nambu-Goldstone (pNG) dark matter (DM) is proposed. We assume that there is an SU(2)g global symmetry and a U(1)X gauge symmetry in the dark sector, and they are spontaneously broken into a U(1)D global symmetry after a scalar field develops a vacuum expectation value. We add a soft symmetry breaking term that breaks the SU(2)g global symmetry into the U(1)g global symmetry explicitly. Our model predicts a stable complex pNG particle under the U(1)D global symmetry. One of the virtues of the pNG DM models is that the models can explain the current null results in the direct detection experiments. The small momentum transfer suppresses the scattering amplitudes thanks to the low energy behavior of the Nambu-Goldstone boson. In our model, the soft symmetry breaking term is uniquely determined. This is the advantage of our model to some earlier works in which some soft symmetry breaking terms cannot be forbidden but are simply assumed to be absent to avoid the constraints from the direct detection experiments. We calculate the thermal relic abundance of the pNG DM and find that model can explain the measured value of the DM energy density under some constraints from the perturbative unitarity.
6 citations
TL;DR: In this article , the authors consider a framework where the dark matter talks to the Standard Model through its coupling to sterile neutrinos, which generate active neutrino masses. But they focus on the case of Majorana dark matter, with its relic abundance set by thermal freeze-out through annihilations into sterile neutrons.
Abstract: A bstract Stringent constraints on the interactions of dark matter with the Standard Model suggest that dark matter does not take part in gauge interactions. In this regard, the possibility of communicating between the visible and dark sectors via gauge singlets seems rather natural. We consider a framework where the dark matter talks to the Standard Model through its coupling to sterile neutrinos, which generate active neutrino masses. We focus on the case of Majorana dark matter, with its relic abundance set by thermal freeze-out through annihilations into sterile neutrinos. We use an effective field theory approach to study the possible sterile neutrino portals to dark matter. We find that both lepton-number-conserving and lepton-number-violating operators are possible, yielding an interesting connection with the Dirac/Majorana character of active neutrinos. In a second step, we open the different operators and outline the possible renormalisable models. We analyse the phenomenology of the most promising ones, including a particular case in which the Majorana mass of the sterile neutrinos is generated radiatively.
6 citations
TL;DR: In this paper , a light thermal scalar dark matter (DM) model with a light scalar mediator mixed with the standard model Higgs boson, including both the theoretical bounds and the current experimental constraints, is studied.
Abstract: We study a light thermal scalar dark matter (DM) model with a light scalar mediator mixed with the standard model Higgs boson, including both the theoretical bounds and the current experimental constraints. The thermal scalar DM with the mass below a few GeV is usually strongly constrained by the observation of cosmic microwave background and/or indirect detection experiments because the leading annihilation mode is S-wave. However, we find that two parameter regions remain, which are the resonant annihilation region and the forbidden annihilation region. For both cases, higher partial waves dominantly contribute to the annihilation at the freeze-out era, and the constraint from the cosmological observation is weaker. We consider typical cases of these regions quantitatively, mainly focusing on the mixing angle and the mass of the new particles. Finally, we also discuss the testability of this model in future experiments.
5 citations
TL;DR: In this article , the authors proposed an inelastic scalar dark matter model with a broken symmetry, which realizes the domination of partner-partner pair annihilation in the coannihilation model.
Abstract: The coannihilation mechanism is a well-motivated alternative to the simple thermal freeze-out mechanism, where the dark matter relic density can be obtained through the coannihilation with a partner particle of similar mass with dark matter. When the partner particle is neutral, the inelastic nature of dark matter can help it to escape the direct detection limits. In this work, we focus on the coannihilation scenario in which the annihilation cross section is dominated by the partner-partner pair annihilation. We pay special interest on the parameter space where the coannihilation partner is long-lived, which leads to displaced signatures at the collider. In such case, it opens the heavy mass parameter space for the coannihilation dark matter, comparing with those dominated by the partner-dark matter annihilation. Specifically, we propose an inelastic scalar dark matter model with a broken symmetry, which realizes the domination of partner-partner pair annihilation. Then, we study two different realizations of the coannihilation partner decay and the existing constraints from the relic abundance, direct and indirect dark matter detection and the collider searches. We focus on the channel that the long-lived coannihilation partner decays to dark matter plus leptons. The high-luminosity LHC can reach good sensitivities for such heavy dark matter and coannihilation partner around 100--700 GeV.
3 citations
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TL;DR: The current status of particle dark matter, including experimental evidence and theoretical motivations, including direct and indirect detection techniques, is discussed in this paper. But the authors focus on neutralinos in models of supersymmetry and Kaluza-Klein dark matter in universal extra dimensions.
4,614 citations
TL;DR: In this paper, the authors present new weak lensing observations of 1E0657-558 (z = 0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law.
Abstract: We present new weak lensing observations of 1E0657-558 (z = 0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law. Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray emitting plasma are spatially segregated. By using both wide-field ground based images and HST/ACS images of the cluster cores, we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies. An 8{sigma} significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law, and thus proves that the majority of the matter in the system is unseen.
2,332 citations
TL;DR: An exact relativistic single-integral formula for the thermal average of the annihilation cross section times velocity, the key quantity in the determination of the cosmic relic abundance of a species, is obtained in this paper.
1,416 citations
TL;DR: In this paper, the authors presented new full-sky temperature and polarization maps based on seven years of data from WMAP, which are consistent with previous results, but have improved due to reduced noise from the additional integration time, improved knowledge of the instrument performance, and improved data analysis procedures.
Abstract: New full-sky temperature and polarization maps based on seven years of data from WMAP are presented. The new results are consistent with previous results, but have improved due to reduced noise from the additional integration time, improved knowledge of the instrument performance, and improved data analysis procedures. The improvements are described in detail. The seven-year data set is well fit by a minimal six-parameter flat ?CDM model. The parameters for this model, using the WMAP data in conjunction with baryon acoustic oscillation data from the Sloan Digital Sky Survey and priors on H 0 from Hubble Space Telescope observations, are ? b h 2 = 0.02260 ? 0.00053, ? c h 2 = 0.1123 ? 0.0035, ?? = 0.728+0.015 ?0.016, ns = 0.963 ? 0.012, ? = 0.087 ? 0.014, and ?8 = 0.809 ? 0.024 (68% CL uncertainties). The temperature power spectrum signal-to-noise ratio per multipole is greater that unity for multipoles ? 919, allowing a robust measurement of the third acoustic peak. This measurement results in improved constraints on the matter density, ? m h 2 = 0.1334+0.0056 ?0.0055, and the epoch of matter-radiation equality, z eq = 3196+134 ?133, using WMAP data alone. The new WMAP data, when combined with smaller angular scale microwave background anisotropy data, result in a 3? detection of the abundance of primordial helium, Y He = 0.326 ? 0.075. When combined with additional external data sets, the WMAP data also yield better determinations of the total mass of neutrinos, ?m ? ? 0.58 eV(95%CL), and the effective number of neutrino species, N eff = 4.34+0.86 ?0.88. The power-law index of the primordial power spectrum is now determined to be ns = 0.963 ? 0.012, excluding the Harrison-Zel'dovich-Peebles spectrum by >3?. These new WMAP measurements provide important tests of big bang cosmology.
1,396 citations
TL;DR: The formation, physical properties and the cosmological evolution of various defects are reviewed, including the string scenario of galaxy formation and possible observational effects of strings.
1,394 citations