Dark SU Research Articles

Cold darkogenesis: Dark matter and baryon asymmetry in light of the PTA signal

We build upon the intriguing possibility that the recently reported nano-Hz gravitational wave signal by Pulsar Timing Array (PTA) experiments is sourced by a strong first-order phase transition from a nearly conformal dark sector. The phase transition has to be strongly supercooled to explain the signal amplitude, while the critical temperature has to be in the O(GeV) range, as dictated by the peak frequency of the gravitational wave spectrum. However, the resulting strong supercooling exponentially dilutes away any pre-existing baryon asymmetry and dark matter, calling for a new paradigm of their productions. We then develop a mechanism of cold darkogenesis that generates a dark asymmetry during the phase transition from the textured dark SU(2)D Higgs field. This dark asymmetry is transferred to the visible sector via neutron portal interactions, resulting in the observed baryon asymmetry. Furthermore, the mechanism naturally leads to the correct abundance of asymmetric dark matter, with self-interaction of the scale that is of the right order to solve the diversity problem in galactic rotation curves. Collider searches for mono-jets and dark matter direct detection experiments can dictate the viability of the model.

A fermionic portal to a non-abelian dark sector

We introduce a new class of renormalizable models for dark matter with a minimal particle content, consisting of a dark SU(2)D gauge sector connected to the standard model through a vector-like fermion mediator, not requiring a Higgs portal, in which a massive vector boson is the dark matter candidate. These models are labeled fermion portal vector dark matter (FPVDM). Multiple realizations are possible, depending on the properties of the vector-like partner and scalar potential. One example is discussed in detail. Fermion portal vector dark matter models have a large number of applications in collider and non-collider experiments, with their phenomenology depending on the mediator sector.

Self-interacting vectorial dark matter in a SM-like dark sector

A dark SU(2) D × U(1) D gauge-Higgs sector, an exact copy of the Standard Model (SM) one, is proposed. It is demonstrated that thedark gauge bosons 𝒲(p,m), in analogous to the SM W ±,can fulfill the role as a self-interacting vector dark matter candidate, solving the core versus cusp and missing satellites problems faced by the conventional paradigm of collisionless weakly interacting massive particle. Constraints from collider, astroparticle and cosmology on such a self-interacting vector dark matter candidate are scrutinized. Implications for the future searches of 𝒲(p,m) in direct detection experiments are discussed.

Dynamical inflation stimulated cogenesis

We propose a minimal setup that realises dynamical inflection point inflation, and, using the same field content, generates neutrino masses, a baryon asymmetry of the universe, and dark matter. A dark SU(2)D gauge sector with a dark scalar doublet playing the role of inflaton is considered along with several doublet and singlet fermions sufficient to realise multiple inflection points in the inflaton potential. The singlet fermions couple to SM leptons and generate neutrino masses via the inverse seesaw mechanism. Those fermions also decay asymmetrically and out of equilibrium, generating a baryon asymmetry via leptogenesis. Some of the fermion doublets are dark matter, and they are produced via inflaton decay and freeze-in annihilation of the same fermions that generate the lepton asymmetry. Reheating, leptogenesis, and dark matter are all at the TeV scale.

The SU(2)$_{D}$ lepton portals for muon g - 2, W boson mass and dark matter

We propose a novel model which extends the Standard Model (SM) by introducing a SU(2)_DSU(2)D gauge symmetry. In this model, a dark SU(2)_DSU(2)D Higgs doublet and a Higgs bi-doublet can contribute to the muon g-2 anomaly and the WW boson mass, remaining in tune with the recent experimental results. At the same time, the isospin charged gauge boson of SU(2)_DSU(2)D becomes a plausible candidate for Dark Matter(DM). We find that the resulting parameter space can fit the muon g-2, the W boson mass and the DM constraints simultaneously.

Gravitational waves from dark SU(3) Yang-Mills theory

We analyze the phase transition in improved holographic QCD to obtain an estimate of the gravitational wave signal emitted in the confinement transition of a pure SU(3) Yang-Mills dark sector. We derive the effective action from holography and show that the energy budget and duration of the phase transition can be calculated with minor errors. These are used as input to obtain a prediction of the gravitational wave signal. To our knowledge, this is the first computation of the gravitational wave signal in a holographic model designated to match lattice data on the thermal properties of pure Yang-Mills.

Glueball Dark Matter Revisited.

We revisit the possibility that dark matter is composed of stable scalar glueballs of a confining dark SU(3) gauge theory coupled only to gravity. The relic abundance of dark glueballs is studied for the first time in a thermal effective theory accounting for strong-coupling dynamics. An important ingredient of our analysis is the use of an effective potential for glueballs that is fitted by lattice simulations. We predict the relic abundance to be in the range 0.12ζ_{T}^{-3}Λ/(137.9 eV)≲Ωh^{2}≲0.12ζ_{T}^{-3}Λ/(82.7 eV), with Λ being the confinement scale, ζ_{T} the visible-to-dark sector temperature ratio, and the uncertainty is coming from the fit to lattice data. This prediction is an order of magnitude smaller than the existing glueball abundance results in the literature. Our framework can be easily generalized to different gauge groups and modified cosmological histories paving the way toward consistent exploration of strongly coupled dark sectors and their cosmological implications.

Self-interacting dark baryons

Using results from lattice QCD, it is possible to quantitatively design models of dark baryons leading to velocity-dependent self-interaction cross sections that match the values needed for solving small-scale structure problems of standard cold dark matter. However it is not obvious that the main dark matter component in such models will be nucleons rather than large nuclei, or dark pions or atoms, whose scattering properties would be different. We first identify the parameters of a dark SU(3) sector analogous to QCD---the confinement scale $\mathrm{\ensuremath{\Lambda}}$ and pion mass ${m}_{\ensuremath{\pi}}$---needed to reproduce desired self-interaction cross sections. Then we show that these values can generically be compatible with the absence of a sufficiently stable deuteron bound state, and hence leading to no heavier nuclei, thus establishing the consistency of the scenario for self-interacting dark nucleons. The range of dark photon masses needed to avoid dominant pion or atomic dark matter is determined, as well as allowed values for the kinetic mixing parameter. The dark proton might be detected directly in future searches, by dark photon exchange.

A first order dark SU(2) D phase transition with vector dark matter in the light of NANOGrav 12.5 yr data

We study a dark SU(2) D gauge extension of the standard model (SM) with the possibility of a strong first order phase transition (FOPT) taking place below the electroweak scale in the light of NANOGrav 12.5 yr data. As pointed out recently by the NANOGrav collaboration, gravitational waves (GW) from such a FOPT with appropriate strength and nucleation temperature can explain their 12.5 yr data. We impose a classical conformal invariance on the scalar potential of SU(2) D sector involving only a complex scalar doublet with negligible couplings with the SM Higgs. While a FOPT at sub-GeV temperatures can give rise to stochastic GW around nano-Hz frequencies being in agreement with NANOGrav findings, the SU(2) D vector bosons which acquire masses as a result of the FOPT in dark sector, can also serve as dark matter (DM) in the universe. The relic abundance of such vector DM can be generated in a non-thermal manner from the SM bath via scalar portal mixing. We also discuss future sensitivity of gravitational wave experiments to the model parameter space.

Testing the dark SU(N) Yang-Mills theory confined landscape: From the lattice to gravitational waves

We pave the way for future gravitational-wave detection experiments, such as the big bang observer and DECIGO, to constraint dark sectors made of $SU(N)$ Yang-Mills confined theories. We go beyond the state-of-the-art by combining first principle lattice results and effective field theory approaches to infer essential information about the nonperturbative dark deconfinement phase transition driving the generation of gravitational-waves in the early Universe, such as the order, duration and energy budget of the phase transition which are essential in establishing the strength of the resulting gravitational-wave signal.

Electroweak phase transition with an SU(2) dark sector

We consider a non-Abelian dark SU(2)D model where the dark sector couples to the Standard Model (SM) through a Higgs portal. We investigate two different scenarios of the dark sector scalars with Z2 symmetry, with Higgs portal interactions that can introduce mixing between the SM Higgs boson and the SM singlet scalars in the dark sector. We utilize the existing collider results of the Higgs signal rate, direct heavy Higgs searches, and electroweak precision observables to constrain the model parameters. The SU(2)D partially breaks into U(1)D gauge group by the scalar sector. The resulting two stable massive dark gauge bosons and pseudo-Goldstone bosons can be viable cold dark matter candidates, while the massless gauge boson from the unbroken U(1)D subgroup is a dark radiation and can introduce long-range attractive dark matter (DM) self-interaction, which can alleviate the small-scale structure issues. We study in detail the pattern of strong first-order phase transition and gravitational wave (GW) production triggered by the dark sector symmetry breaking, and further evaluate the signal-to-noise ratio for several proposed space interferometer missions. We conclude that the rich physics in the dark sector may be observable with the current and future measurements at colliders, DM experiments, and GW interferometers.

Vector dark matter from split SU(2) gauge bosons

We propose a vector dark matter model with an exotic dark SU(2) gauge group. Two Higgs triplets are introduced to spontaneously break the symmetry. All of the dark gauge bosons become massive, and the lightest one is a viable vector DM candidate. Its stability is guaranteed by a remaining Z2 symmetry. We study the parameter space constrained by the Higgs measurement data, the dark matter relic density, and direct and indirect detection experiments. We find numerous parameter points satisfying all the constraints, and they could be further tested in future experiments. Similar methodology can be used to construct vector dark matter models from an arbitrary SO(N) gauge group.

Direct detection of vector dark matter through electromagnetic multipoles

Dark matter particles, even if they are electrically neutral, could interact with the Standard Model particles via their electromagnetic multipole moments. In this paper, we focus on the electromagnetic properties of the complex vector dark matter candidate, which can be described by means of seven form factors. We calculate the differential scattering cross-section with nuclei due to the interactions of the dark matter and nuclear multipole moments, and we derive upper limits on the former from the non-observation of dark matter signals in direct detection experiments. We also present a model where the dark matter particle is a gauge boson of a dark SU(2) symmetry, and which contains heavy new fermions, charged both under the dark SU(2) symmetry and under the electromagnetic U(1) symmetry. The new fermions induce at the one loop level electromagnetic multipole moments, which could lead to detectable signals in direct detection experiments.

Baryogenesis from a dark first-order phase transition

We present a very minimal model for baryogenesis by a dark first-order phase transition. It employs a new dark SU(2)D gauge group with two doublet Higgs bosons, two lepton doublets, and two singlets. The singlets act as a neutrino portal that transfer the generated asymmetry to the Standard Model. The model predicts ∆Neff = 0.09–0.13 detectable by future experiments as well as possible signals from exotic decays of the Higgs and Z bosons and stochastic gravitational waves.

Multicomponent dark matter from a hidden gauged SU(3)

We study Dark Matter (DM) phenomenology with multiple DM species consisting of both scalar and vector DM particles. More specifically, we study the Hidden Gauged SU(3) model of Arcadi {\it et al}. Before proceeding to the Hidden Gauged SU(3) model, we study the relic abundances of simplified multi-species DM scenarios to gain some insights when multiple species and interactions are included. In the Hidden Gauged SU(3) model, because of the large parameter space, we restrict ourselves to three representative benchmark points, each with multiple DM species. The relic densities for the benchmark points were found using a program developed to solve the coupled Boltzmann equations for an arbitrary number of interacting DM species with two particles in the final state. For each case, we varied the mass of the DM particles and then found the value of the dark SU(3) gauge coupling that gives the correct relic density. We found that in some regions of the parameter space, the DM would be difficult to observe in direct detection experiments while easier to observe in indirect detection experiments and vice versa, so that complementary measurements could help pinpoint the details of the Hidden Gauged SU(3) model. Important to this, is that even for moderate changes in input parameter values, the relative relic density of each species can change significantly resulting in large changes in the observability of multi-species DM by direct or indirect detection.

Dark sector portal with vectorlike leptons and flavor sequestering

We consider models with fermionic dark matter that transforms under a non-Abelian dark gauge group. Exotic, vectorlike leptons that also transform under the dark gauge group can mix with standard model leptons after spontaneous symmetry breaking and serve as a portal between the dark and visible sectors. We show in an explicit, renormalizable model based on a dark SU(2) gauge group how this can lead to adequate dark matter annihilation to a standard model lepton flavor so that the correct relic density is obtained. We identify a discrete symmetry that allows mass mixing between the vectorlike fermions and a single standard model lepton flavor, while preventing mixing between these fields and the remaining standard model leptons. This flavor sequestering avoids unwanted lepton-flavor-violating effects, substantially relaxing constraints on the mass scale of the vectorlike states. We discuss aspects of the phenomenology of the model, including direct detection of the dark matter.

Interacting Dark Energy in the Dark SU(2) R Model

We explore the cosmological implications of the interactions among the dark particles in the dark $SU(2)_R$ model. It turns out that the relevant interaction is between dark energy and dark matter, through a decay process. With respect to the standard $\Lambda$CDM model, it changes only the background equations. We note that the observational aspects of the model are dominated by degeneracies between the parameters that describe the process. Thus, only the usual $\Lambda$CDM parameters, such as the Hubble expansion rate and the dark energy density parameter (interpreted as the combination of the densities of the dark energy doublet) could be constrained by observations at this moment.

Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector

All pieces of concrete evidence for phenomena outside the standard model (SM) - neutrino masses and dark matter - are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral SU(3) x SU(2) gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark SU(2) is spontaneously broken while the dark SU(3) confines at low energies. At the renormalizable level, the dark sector contains massless fermions - dark leptons - and stable massive particles - dark protons. We find that dark protons with masses between 10-100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new "neutrino" and "dark matter" degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early universe cosmology while indirect searches for dark matter involve, decisively, dark matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross-section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.

Exploring a hidden fermionic dark sector

We propose a hidden sector fermion dark matter model which follows a dark SU(2) $$_\mathrm {H}$$ symmetry. Fermions in the dark sector also carry a global U(1) $$_\mathrm {H}$$ charge while the gauge bosons and dark scalar do not have any global U(1) $$_\mathrm {H}$$ charge. The lightest fermion in dark sector can serve as a potential dark matter candidate. We investigate whether the proposed dark matter candidate can explain indirect detection results from galactic centre.

Dark SU(N) glueball stars on fluid branes

The glueball dark matter, in the pure SU(N) Yang-Mills theory, engenders dark SU(N) stars that comprise self-gravitating compact configurations of scalar glueball fields. Corrections to the highest frequency of gravitational wave radiation emitted by dark SU(N) star mergers on a fluid brane with variable tension, implemented by the minimal geometric deformation, are derived and their consequences analysed. Hence, dark SU(N) stars mergers on a fluid brane-world are shown to be better detectable by the LIGO and the eLISA experiments.