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 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 Exothermic dark mesons in light of electron recoil excess at XENON1T

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Soo-Min Choi ◽  
Hyun Min Lee ◽  
Bin Zhu
Keyword(s):  
Dark Matter ◽  
Inelastic Scattering ◽  
Small Mass ◽  
Density Current ◽  
Flavor Symmetry ◽  
Color Group ◽  
Dark Sector ◽  
The Standard Model ◽  
Electron Recoil ◽  
Relic Density

Abstract We consider a novel mechanism to realize exothermic dark matter with dark mesons in the limit of approximate flavor symmetry in a dark QCD. We introduce a local dark U(1)′ symmetry to communicate between dark mesons and the Standard Model via Z′ portal by partially gauging the dark flavor symmetry with flavor-dependent charges for cancelling chiral anomalies in the dark sector. After the dark local U(1)′ is broken spontaneously by the VEV of a dark Higgs, there appear small mass splittings between dark quarks, consequently, leading to small split masses for dark mesons, required to explain the electron recoil excess in XENON1T by the inelastic scattering between dark mesons and electron. We propose a concrete benchmark model for split dark mesons based on SU(3)L× SU(3)R/SU(3)V flavor symmetry and SU(Nc) color group and show that there exists a parameter space making a better fit to the XENON1T data with two correlated peaks from exothermic processes and satisfying the correct relic density, current experimental and theoretical constraints.

scholarly journals Exothermic dark matter for XENON1T excess

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Hyun Min Lee
Keyword(s):  
Dark Matter ◽  
Mass Difference ◽  
Mass Splitting ◽  
Effective Theory ◽  
Recoil Energy ◽  
Detector Resolution ◽  
Atomic Excitation ◽  
Microscopic Models ◽  
Electron Recoil ◽  
Two Component

Abstract Motivated by the recent excess in the electron recoil from XENON1T experiment, we consider the possibility of exothermic dark matter, which is composed of two states with mass splitting. The heavier state down-scatters off the electron into the lighter state, making an appropriate recoil energy required for the Xenon excess even for the standard Maxwellian velocity distribution of dark matter. Accordingly, we determine the mass difference between two component states of dark matter to the peak electron recoil energy at about 2.5 keV up to the detector resolution, accounting for the recoil events over ER = 2 − 3 keV, which are most significant. We include the effects of the phase-space enhancement and the atomic excitation factor to calculate the required scattering cross section for the Xenon excess. We discuss the implications of dark matter interactions in the effective theory for exothermic dark matter and a massive Z′ mediator and provide microscopic models realizing the required dark matter and electron couplings to Z′.

scholarly journals Astrophysical aspects of milli-charged dark matter in a Higgs–Stueckelberg model

2015 ◽  
Vol 30 (18) ◽  
pp. 1550089 ◽  
Author(s):  
A. L. dos Santos ◽  
D. Hadjimichef
Keyword(s):  
Dark Matter ◽  
Weakly Interacting Massive Particles ◽  
Dark Sector ◽  
Minimal Coupling ◽  
Astrophysical Application ◽  
Gauge Sector ◽  
Dark Photon ◽  
The Standard Model ◽  
Vector Bosons ◽  
The Impact

An extension of the Standard Model (SM) is studied, in which two new vector bosons are introduced, a first boson Z' coupled to the SM by the usual minimal coupling, producing an enlarged gauge sector in the SM. The second boson A' field, in the dark sector of the model, remains massless and originates a dark photon γ'. A hybrid mixing scenario is considered based on a combined Higgs and Stueckelberg mechanisms. In a Compton-like process, a photon scattered by a weakly interacting massive particles (WIMP) is converted into a dark photon. This process is studied, in an astrophysical application obtaining an estimate of the impact on stellar cooling of white dwarfs and neutron stars.

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 The THDMa Revisited

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2341
Author(s):  
Tania Robens
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
B Physics ◽  
A Priori ◽  
New Physics ◽  
Dark Sector ◽  
The Standard Model ◽  
Future Collider ◽  
Physics Model ◽  
Scalar Sector

The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge-eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spins states. The option where dark matter is fermionic is currently one of the standard benchmarks for the experimental collaborations, and several searches at the LHC constrain the corresponding parameter space. However, most current studies constrain regions in parameter space by setting all but 2 of the 12 free parameters to fixed values. In this work, we performed a generic scan on this model, allowing all parameters to float. We applied all current theoretical and experimental constraints, including bounds from current searches, recent results from B-physics, in particular Bs→Xsγ, as well as bounds from astroparticle physics. We identify regions in the parameter space which are still allowed after these were applied and which might be interesting for an investigation of current and future collider machines.

scholarly journals Long-lived dark Higgs and inelastic dark matter at Belle II

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Michael Duerr ◽  
Torben Ferber ◽  
Camilo Garcia-Cely ◽  
Christopher Hearty ◽  
Kai Schmidt-Hoberg
Keyword(s):  
Dark Matter ◽  
Higgs Field ◽  
Mass Splitting ◽  
Dark Sector ◽  
Missing Momentum ◽  
Belle Ii ◽  
Displaced Vertex ◽  
Inelastic Dark Matter ◽  
Near Future ◽  
Matter Detection

Abstract Inelastic dark matter is an interesting scenario for light thermal dark matter which is fully consistent with all cosmological probes as well as direct and indirect dark matter detection. The required mass splitting between dark matter χ1 and its heavier twin χ2 is naturally induced by a dark Higgs field which also provides a simple mechanism to give mass to the dark photon A′ present in the setup. The corresponding dark Higgs boson h′ is naturally the lightest dark sector state and therefore decays into Standard Model particles via Higgs mixing. In this work we study signatures with displaced vertices and missing momentum at Belle II, arising from dark Higgs particles produced in association with dark matter. We find that Belle II can be very sensitive to this scenario, in particular if a displaced vertex trigger is available in the near future.

scholarly journals Dark photon search at Yemilab, Korea

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
S. H. Seo ◽  
Y. D. Kim
Keyword(s):  
Electron Beam ◽  
Confidence Level ◽  
Particle Physics ◽  
Absorption Process ◽  
Neutrino Detector ◽  
Dark Sector ◽  
Dark Photon ◽  
Mixing Parameter ◽  
The Standard Model ◽  
Background Events

Abstract Dark photons are well motivated hypothetical dark sector particles that could account for observations that cannot be explained by the standard model of particle physics. A search for dark photons that are produced by an electron beam striking a thick tungsten target and subsequently interact in a 3 kiloton-scale neutrino detector in Yemilab, a new underground lab in Korea, is proposed. Dark photons can be produced by “darkstrahlung” or by oscillations from ordinary photons produced in the target and detected by their visible decays, “absorption” or by their oscillation to ordinary photons. By detecting the absorption process or the oscillation-produced photons, a world’s best sensitivity for measurements of the dark-photon kinetic mixing parameter of ϵ2> 1.5 × 10−13(6.1 × 10−13) at the 95% confidence level (C.L.) could be obtained for dark photon masses between 80 eV and 1 MeV in a year-long exposure to a 100 MeV–100 kW electron beam with zero (103) background events. In parallel, the detection of e+e− pairs from decays of dark photons with mass between 1 MeV and ∼86 MeV would have sensitivities of ϵ2>$$ \mathcal{O}\left({10}^{-17}\right)\left(\mathcal{O}\left({10}^{-16}\right)\right) $$ O 10 − 17 O 10 − 16 at the 95% C.L. with zero (103) background events. This is comparable to that of the Super-K experiment under the same zero background assumption.

scholarly journals The building blocks of the universe

2021 ◽  
Vol 77 (3) ◽  
Author(s):  
Anslyn J. John
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Building Blocks ◽  
Big Bang ◽  
The State ◽  
Dark Sector ◽  
Big Bang Nucleosynthesis ◽  
Ordinary Matter ◽  
Special Collection ◽  
The Universe

I review the state of knowledge of the composition of the universe for a non-specialist audience. The universe is built up of four components. These are radiation, baryonic (ordinary) matter, dark matter and dark energy. In this article, a quick outline of the theory of Big Bang nucleosynthesis is presented, and the origin of the elements is explained. Cosmology requires the presence of dark matter, which forms most of the mass of the universe, and dark energy, which drives the acceleration of the expansion. The dark sector is motivated, and possible explanations are stated.Contribution: As part of this special collection on building blocks, the building blocks of the universe are discussed and unsolved problems and proposed solutions are highlighted.

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.

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