scholarly journals Hidden sector monopole dark matter with matter domination

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Michael L. Graesser ◽  
Jacek K. Osiński

Abstract The thermal freeze-out mechanism for relic dark matter heavier than O(10 − 100 TeV) requires cross-sections that violate perturbative unitarity. Yet the existence of dark matter heavier than these scales is certainly plausible from a particle physics perspective, pointing to the need for a non-thermal cosmological history for such theories. Topological dark matter is a well-motivated scenario of this kind. Here the hidden-sector dark matter can be produced in abundance through the Kibble-Zurek mechanism describing the non-equilibrium dynamics of defects produced in a second order phase transition. We revisit the original topological dark matter scenario, focusing on hidden-sector magnetic monopoles, and consider more general cosmological histories. We find that a monopole mass of order (1–105) PeV is generic for the thermal histories considered here, if monopoles are to entirely reproduce the current abundance of dark matter. In particular, in a scenario involving an early era of matter domination, the monopole number density is always less than or equal to that in a pure radiation dominated equivalent provided a certain condition on critical exponents is satisfied. This results in a larger monopole mass needed to account for a fixed relic abundance in such cosmologies.

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jochem Hauser ◽  
Walter Dröscher

Abstract This article, the last in a series of three articles, attempts to unravel the underlying physics of recent experiments regarding the contradictory properties of the neutron lifetime that has been a complete riddle for quite some time. So far, none of the advanced theories beyond the  Standard Models (SMs) of particle physics and cosmology have shown sufficient potential to resolve this mystery. We also try to explain the blatant contradiction between the predictions of particle physics and experiments concerning the nature and properties of the (so far undetected) dark matter and dark energy particles. To this end the novel concepts of both negative and hypercomplex matter (giving rise to the concept of matter flavor) are introduced, replacing the field of real numbers by hypercomplex numbers. This extension of the number system in physics leads to both novel internal symmetries requiring new elementary particles – as outlined in Part I and II, and to novel types of matter. Hypercomplex numbers are employed in place of the widely accepted (but never observed) concept of extra space dimensions – and, hence, also to question the corresponding concept of supersymmetry. To corroborate this claim, we report on the latest experimental searches for novel and supersymmetric elementary particles by direct searches at the Large Hadron Collider (LHC) and other colliders as well as numerous other dedicated experiments that all have come up empty handed. The same holds true for the dark matter search at European Council for Nuclear Research (CERN) [CERN Courier Team, “Funky physics at KIT,” in CERN Courier, 2020, p. 11]. In addition, new experiments looking for dark or hidden photons (e.g., FUNK at Karlsruhe Institute of Technology, CAST at CERN, and ALPS at Desy, Hamburg) are discussed that all produced negative results for the existence of the hitherto unseen but nevertheless gravitationally noticeably dark matter. In view of this contradicting outcome, we suggest a four-dimensional Minkowski spacetime, assumed to be a quasi de Sitter space, dS 1,3, complemented by a dual spacetime, denoted by DdS 1,3, in which the dark matter particles that are supposed to be of negative mass reside. This space is endowed with an imaginary time coordinate, −it and an imaginary speed of light, ic. This means that time is considered a complex quantity, but energy m(ic)2 > 0. With this construction visible and dark matter both represent positive energies, and hence gravitation makes no distinction between these two types of matter. As dark matter is supposed to reside in dual space DdS 1,3, it is principally undetectable in our spacetime. That this is evident has been confirmed by numerous astrophysical observations. As the concept of matter flavor may possibly resolve the contradictory experimental results concerning the lifetime of the neutron [J. T. Wilson, “Space based measurement of the neutron lifetime using data from the neutron spectrometer on NASA’s messenger mission,” Phys. Rev. Res., vol. 2, p. 023216, 2020] this fact could be considered as a first experimental hint for the actual existence of hypercomplex matter. In canonical gravity the conversion of electromagnetic into gravity-like fields (as surmised by Faraday and Einstein) should be possible, but not in cosmological gravity (hence these attempts did not succeed), and thus these conversion fields are outside general relativity. In addition, the concept of hypercomplex mass in conjunction with magnetic monopoles emerging from spin ice materials is discussed that may provide the enabling technology for long sought propellantless space propulsion.


2018 ◽  
Vol 182 ◽  
pp. 02034
Author(s):  
Wim de Boer

Up to now searches for Dark Matter (DM) detection have not been successful, either because our paradigm in howDMsignals should look like are wrong or the detector sensitivity is still too low in spite of the large progress made in recent years. We discuss both possibilities starting with what we know about DM from cosmology and why Supersymmetry provides such an interesting paradigm for cosmology and particle physics in order to appreciate what it means to give up this paradigm. In addition, we compare the predicted cross sections for direct and indirect DM detection with observations with emphasis on the latest developments. Especially, we discuss the possible origins of the two hotly debated candidates for a DM annihilation signal, namely the positron excess and the Fermi GeV excess, which are unfortunately incompatible with each other and more mundane astrophysical explanations exist.


Author(s):  
Ricardo G. Landim

Abstract Extra dimensions (ED) have been used as attempts to explain several phenomena in particle physics over the years. In this paper we investigate the role of an abelian gauge field as mediator of the interaction between dark matter (DM) and Standard Model (SM) particles, in a model with two flat and transverse ED compactified on the chiral square. DM is confined in a thin brane, localized at the origin of the chiral square, while the SM is localized in a finite width brane, lying in the opposite corner of the square. A brane-localized kinetic term is present in the DM brane, while in the fat brane it is not allowed. In this model the kinetic mixing is not required because we assume that the SM particles couple to the mediator through their $$B-L$$B-L charges, while DM couples to it via a dark charge. Assuming a complex scalar field as DM candidate it is possible to obtain the observed DM relic abundance and avoid direct detection constraints for some parameter choices.


2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Jérôme Claude ◽  
Stephen Godfrey

AbstractWe explore regions of parameter space that give rise to suppressed direct detection cross sections in a simple model of scalar dark matter with a scalar portal that mixes with the standard model Higgs. We found that even this simple model allows considerable room in the parameter space that has not been excluded by direct detection limits. A number of effects leading to this result have been previously noted. Our main new result explores interference effects between different contributions to DM annihilation when the DM mass is larger than the scalar portal mass. New annihilation channels open up and the parameters of the model need to compensate to give the correct DM relic abundance, resulting in smaller direct detection cross sections. We find that even in a very simple model of DM there are still sizeable regions of parameter space that are not ruled out by experiment.


2005 ◽  
Vol 14 (04) ◽  
pp. 631-633
Author(s):  
B. G. SIDHARTH

Recently, Boehm and co-workers have analyzed the newly detected 511 keV gamma rays from the galactic bulge based on data obtained from INTEGRAL. They conclude that these gamma rays are a consequence of low mass (~ MeV ) particle dark matter annihilations. Their conclusions are consistent with the halo profile favored by the observations, the annihilation cross-sections required for the radiation and also other astro particle physics constraints.1,2 It may be pointed out that exactly such a production of gamma rays from MeV particles was predicted by the author3 some years ago. This was based on a consideration of extremal black holes. We would like to point out that there is a spectrum of possible candidates.


2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Yong Du ◽  
Fei Huang ◽  
Hao-Lin Li ◽  
Jiang-Hao Yu

Abstract We investigate a simplified freeze-in dark-matter model in which the dark matter only interacts with the standard-model neutrinos via a light scalar. The extremely small coupling for the freeze-in mechanism is naturally realized in several neutrino-portal scenarios with the secret neutrino interactions. We study possible evolution history of the hidden sector: the dark sector would undergo pure freeze-in production if the interactions between the dark-sector particles are negligible, while thermal equilibrium within the dark sector could occur if the reannihilation of the dark matter and the scalar mediator is rapid enough. We investigate the relic abundance in the freeze-in and dark freeze-out regimes, calculate evolution of the dark temperature, and study its phenomenological aspects on BBN and CMB constraints, the indirect-detection signature, as well as the potential to solve the small scale structure problem.


2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Amin Aboubrahim ◽  
Pran Nath ◽  
Zhu-Yao Wang

Abstract Analysis of EDGES data shows an absorption signal of the redshifted 21-cm line of atomic hydrogen at z ∼ 17 which is stronger than expected from the standard ΛCDM model. The absorption signal interpreted as brightness temperature T21 of the 21-cm line gives an amplitude of $$ -{500}_{-500}^{+200} $$ − 500 − 500 + 200 mK at 99% C.L. which is a 3.8σ deviation from what the standard ΛCDM cosmology gives. We present a particle physics model for the baryon cooling where a fraction of the dark matter resides in the hidden sector with a U(1) gauge symmetry and a Stueckelberg mechanism operates mixing the visible and the hidden sectors with the hidden sector consisting of dark Dirac fermions and dark photons. The Stueckelberg mass mixing mechanism automatically generates a millicharge for the hidden sector dark fermions providing a theoretical basis for using millicharged dark matter to produce the desired cooling of baryons seen by EDGES by scattering from millicharged dark matter. We compute the relic density of the millicharged dark matter by solving a set of coupled equations for the dark fermion and dark photon yields and for the temperature ratio of the hidden sector and the visible sector heat baths. For the analysis of baryon cooling, we analyze the evolution equations for the temperatures of baryons and millicharged dark matter as a function of the redshift. We exhibit regions of the parameter space which allow consistency with the EDGES data. We note that the Stueckelberg mechanism arises naturally in strings and the existence of a millicharge would point to its string origin.


2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Thomas Biekötter ◽  
María Olalla Olea-Romacho

Abstract We investigate a possible realization of pseudo-Nambu-Goldstone (pNG) dark matter in the framework of a singlet-extended 2 Higgs doublet model (S2HDM). pNG dark matter gained attraction due to the fact that direct-detection constraints can be avoided naturally because of the momentum-suppressed scattering cross sections, whereas the relic abundance of dark matter can nevertheless be accounted for via the usual thermal freeze-out mechanism. We confront the S2HDM with a multitude of theoretical and experimental constraints, paying special attention to the theoretical limitations on the scalar potential, such as vacuum stability and perturbativity. In addition, we discuss the complementarity between constraints related to the dark matter sector, on the one hand, and to the Higgs sector, on the other hand. In our numerical discussion we explore the Higgs funnel region with dark matter masses around 60 GeV using a genetic algorithm. We demonstrate that the S2HDM can easily account for the measured relic abundance while being in agreement with all relevant constraints. We also discuss whether the so-called center-of-galaxy excesses can be accommodated, possibly in combination with a Higgs boson at about 96 GeV that can be the origin of the LEP- and the CMS-excess observed at this mass in the b$$ \overline{b} $$ b ¯ -quark and the diphoton final state, respectively.


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