scholarly journals A cosmologically consistent millicharged dark matter solution to the EDGES anomaly of possible string theory origin

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Amin Aboubrahim ◽  
Pran Nath ◽  
Zhu-Yao Wang
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Evolution Equations ◽  
Dirac Fermions ◽  
Absorption Signal ◽  
Hidden Sector ◽  
Coupled Equations ◽  
Dark Photon ◽  
Visible Sector ◽  
Physics Model

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.

scholarly journals Xenon-1T excess as a possible signal of a sub-GeV hidden sector dark matter

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Amin Aboubrahim ◽  
Michael Klasen ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Small Mass ◽  
Big Bang ◽  
Mass Splitting ◽  
Recoil Energy ◽  
Dirac Fermions ◽  
Dark Sector ◽  
Dark Photon ◽  
Physics Model

Abstract We present a particle physics model to explain the observed enhancement in the Xenon-1T data at an electron recoil energy of 2.5 keV. The model is based on a U(1) extension of the Standard Model where the dark sector consists of two essentially mass degenerate Dirac fermions in the sub-GeV region with a small mass splitting interacting with a dark photon. The dark photon is unstable and decays before the big bang nucleosynthesis, which leads to the dark matter constituted of two essentially mass degenerate Dirac fermions. The Xenon-1T excess is computed via the inelastic exothermic scattering of the heavier dark fermion from a bound electron in xenon to the lighter dark fermion producing the observed excess events in the recoil electron energy. The model can be tested with further data from Xenon-1T and in future experiments such as SuperCDMS.

scholarly journals Hidden sector monopole dark matter with matter domination

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Michael L. Graesser ◽  
Jacek K. Osiński
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Particle Physics ◽  
Magnetic Monopoles ◽  
Number Density ◽  
Pure Radiation ◽  
Hidden Sector ◽  
Equilibrium Dynamics ◽  
Thermal Histories ◽  
Relic Abundance

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.

scholarly journals Status of the PADME experiment and review of dark photon searches

2018 ◽  
Vol 179 ◽  
pp. 01020 ◽  
Author(s):  
M. Raggi
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
High Sensitivity ◽  
Low Energy ◽  
Current Status ◽  
Dark Photon

While accelerator particle physics has traditionally focused on exploring dark matter through highenergy experiments, testing dark-sectors hypothesis requires innovative low energy experiments that use highintensity beams and high-sensitivity detectors. In this scenario attractive opportunities are offered to low energy machines and flavour experiments. In this paper we will focus our attention on the Dark Photon (DP) scenario, reviewing the current status of searches and new opportunities with particular attention to the PADME experiment at Laboratori Nazionali di Frascati.

scholarly journals A multi-temperature universe can allow a sub-MeV dark photon dark matter

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Amin Aboubrahim ◽  
Wan-Zhe Feng ◽  
Pran Nath ◽  
Zhu-Yao Wang
Keyword(s):  
Dark Matter ◽  
Boltzmann Equations ◽  
Dark Photon ◽  
Indirect Coupling ◽  
Visible Sector

Abstract An analysis of sub-MeV dark photon as dark matter is given which is achieved with two hidden sectors, one of which interacts directly with the visible sector while the second has only indirect coupling with the visible sector. The formalism for the evolution of three bath temperatures for the visible sector and the two hidden sectors is developed and utilized in solution of Boltzmann equations coupling the three sectors. We present exclusion plots where the sub-MeV dark photon can be dark matter. The analysis can be extended to a multi-temperature universe with multiple hidden sectors and multiple heat baths.

scholarly journals Inflation and dark matter after spontaneous Planck scale generation by hidden chiral symmetry breaking

2022 ◽  
Vol 2022 (01) ◽  
pp. 005
Author(s):  
Mayumi Aoki ◽  
Jisuke Kubo ◽  
Jinbo Yang
Keyword(s):  
Dark Matter ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Planck Scale ◽  
Energy Scale ◽  
Dynamical Chiral Symmetry Breaking ◽  
Hidden Sector ◽  
Visible Sector

Abstract Dynamical chiral symmetry breaking in a QCD-like hidden sector is used to generate the Planck mass and the electroweak scale including the heavy right-handed neutrino mass. A real scalar field transmits the energy scale of the hidden sector to the visible sectors, playing besides a role of inflaton in the early Universe while realizing a Higgs-inflation-like model. Our dark matter candidates are hidden pions that raise due to dynamical chiral symmetry breaking. They are produced from the decay of inflaton. Unfortunately, it will be impossible to directly detect them, because they are super heavy (109 ∼ 12 GeV), and moreover the interaction with the visible sector is extremely suppressed.

scholarly journals Dark matter to baryon ratio from scalar triplets decay in type-II seesaw

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Nimmala Narendra ◽  
Narendra Sahu ◽  
Sujay Shil
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Direct Detection ◽  
Dirac Fermion ◽  
Model Parameters ◽  
Type Ii ◽  
Dark Sector ◽  
Coincidence Problem ◽  
Electroweak Phase Transition ◽  
Visible Sector

AbstractWe propose a minimal model for the cosmic coincidence problem $$\Omega _\mathrm{DM}/\Omega _B \sim 5$$ Ω DM / Ω B ∼ 5 and neutrino mass in a type-II seesaw scenario. We extend the standard model of particle physics with a $$\mathrm SU(2)$$ S U ( 2 ) singlet leptonic Dirac fermion $$\chi $$ χ , which represents the candidate of dark matter (DM), and two triplet scalars $$\Delta _{1,2}$$ Δ 1 , 2 with hierarchical masses. In the early Universe, the CP violating out-of-equilibrium decay of lightest $$\Delta $$ Δ generates a net $$B-L$$ B - L asymmetry in the visible sector (comprising of SM fields), where B and L represents the total baryon and lepton number respectively. A part of this asymmetry gets transferred to the dark sector (comprising of DM $$\chi $$ χ ) through a dimension eight operator which conserves $$B-L$$ B - L . Above the electroweak phase transition, the $$B-L$$ B - L asymmetry of the visible sector gets converted to a net B-asymmetry by the $$B+L$$ B + L violating sphalerons, while the $$B-L$$ B - L asymmetry of the dark sector remains untouched which we see today as relics of DM. We show that the observed DM abundance can be explained for a DM mass about 8 GeV. We then introduce an additional singlet scalar field $$\phi $$ ϕ which mixes with the SM-Higgs to annihilate the symmetric component of the DM resonantly which requires the singlet scalar mass to be twice the DM mass, i.e. around 16 GeV, which can be searched at collider experiments. In our model, the active neutrinos also get small masses by the induced vacuum expectation value (vev) of the triplet scalars $$\Delta _{1,2}$$ Δ 1 , 2 . In the later part of the paper we discuss all the constraints on model parameters coming from invisible Higgs decay, Higgs signal strength, DM direct detection and relic density of DM.

scholarly journals DARK MATTER ANNIHILATION EXPLANATION FOR e± EXCESSES IN COSMIC RAY

2009 ◽  
Vol 24 (27) ◽  
pp. 2139-2160 ◽  
Author(s):  
XIAO-GANG HE
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Cosmic Ray ◽  
Proton Spectrum ◽  
Annihilation Rate ◽  
Dark Matter Annihilation ◽  
Data Set ◽  
Boost Factor ◽  
Physics Model ◽  
Correct Data

Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are e± excesses in the cosmic ray energy spectrum. PAMELA shown excesses only in e+, but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS shown excesses in e++e- spectrum, but the detailed shapes are different which requires future experimental observations to pin down the correct data set. Nevertheless a lot of efforts have been made to explain the observed e± excesses, and also why PAMELA only has excesses in e+ but not in anti-proton. In this brief review we discuss one of the most popular mechanisms to explain the data — the dark matter annihilation. It has long been known that about 23% of our universe is made of relic dark matter. If the relic dark matter was thermally produced, the annihilation rate is constrained resulting in the need of a large boost factor to explain the data. We will discuss in detail how a large boost factor can be obtained by the Sommerfeld and Breit–Wigner enhancement mechanisms. Some implications for particle physics model buildings will also be discussed.

scholarly journals Chiral composite asymmetric dark matter

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Masahiro Ibe ◽  
Shin Kobayashi ◽  
Keiichi Watanabe
Keyword(s):  
Dark Matter ◽  
Flavor Symmetry ◽  
Dark Sector ◽  
Coincidence Problem ◽  
Dark Photon ◽  
The Standard Model ◽  
Visible Sector ◽  
Dynamical Breaking ◽  
Asymmetric Dark Matter ◽  
The Masses

Abstract The asymmetric dark matter (ADM) scenario solves the baryon-dark matter coincidence problem when the dark matter (DM) mass is of $$ \mathcal{O}(1) $$ O 1 GeV. Composite ADM models based on QCD-like strong dynamics are particularly motivated since the strong dynamics naturally provides the DM mass of $$ \mathcal{O}(1) $$ O 1 GeV and the large annihilation cross-section simultaneously. In those models, the sub-GeV dark photon often plays an essential role in transferring the excessive entropy in the dark sector into the visible sector, i.e., the Standard Model sector. This paper constructs a chiral composite ADM model where the U(1)D gauge symmetry is embedded into the chiral flavor symmetry. Due to the dynamical breaking of the chiral flavor symmetry, the model naturally provides the masses of the dark photon and the dark pions in the sub-GeV range, both of which play crucial roles for a successful ADM model.

scholarly journals CONSTANT SURFACE GRAVITY AND DENSITY PROFILE OF DARK MATTER

2011 ◽  
Vol 26 (06) ◽  
pp. 1057-1072 ◽  
Author(s):  
H. J. DE VEGA ◽  
N. G. SANCHEZ
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Particle Physics ◽  
Black Hole Entropy ◽  
Density Fluctuations ◽  
Surface Gravity ◽  
Density Profiles ◽  
Physics Model ◽  
Physical Consequences ◽  
Remarkable Agreement

Cumulative observational evidence confirms that the surface gravity of dark matter (DM) halos μ0 D = r0ρ0, where r0 and ρ0 are the halo core radius and central density, respectively, is nearly constant and independent of galaxy luminosity for a high number of galactic systems (spirals, dwarf irregular and spheroidals, elliptics) spanning over 14 magnitudes in luminosity and of different Hubble types. Remarkably, its numerical value, μ0D ≃140M⊙/ pc 2 = (18.6 MeV )3, is approximately the same (up to a factor of 2) in all these systems. First, we present the physical consequences of the independence of μ0D from r0: the energy scales as the volume [Formula: see text], while the mass and the entropy scale as the surface [Formula: see text] and the surface times log r0, respectively. Namely, the entropy scales similarly to the black hole entropy but with a much smaller coefficient. Second, we compute the surface gravity and the density profile for small scales from first principles and the evolution of primordial density fluctuations from the end of inflation till today using the linearized Boltzmann–Vlasov equation. The density profile ρ lin (r) obtained in this way decreases as r-1-ns/2 for intermediate scales, where ns≃0.964 is the primordial spectral index. This scaling is in remarkable agreement with the empirical behavior found observationally and in N-body simulations: r-1.6±0.4. The observed value of μ0D indicates that the DM particle mass m is on the keV scale. The theoretically derived density profiles ρ lin (r) turn to be cored for m on the keV scale and they are cusped for m on the GeV scale or beyond. We consider both fermions and bosons as DM particles decoupling either ultrarelativistically or nonrelativistically. Our results do not use any particle physics model and vary slightly with the statistics of the DM particle.

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