Exothermic dark matter for XENON1T excess

103

Motivated by the recent XENON1T results, we explore various new physics models that can be discovered through searches for electron recoils in $$ \mathcal{O} $$ O (keV)-threshold direct-detection experiments. First, we consider the absorption of axion-like particles, dark photons, and scalars, either as dark matter relics or being produced directly in the Sun. In the latter case, we find that keV mass bosons produced in the Sun provide an adequate fit to the data but are excluded by stellar cooling constraints. We address this tension by introducing a novel Chameleon-like axion model, which can explain the excess while evading the stellar bounds. We find that absorption of bosonic dark matter provides a viable explanation for the excess only if the dark matter is a dark photon or an axion. In the latter case, photophobic axion couplings are necessary to avoid X-ray constraints. Second, we analyze models of dark matter-electron scattering to determine which models might explain the excess. Standard scattering of dark matter with electrons is generically in conflict with data from lower-threshold experiments. Momentum-dependent interactions with a heavy mediator can fit the data with dark matter mass heavier than a GeV but are generically in tension with collider constraints. Next, we consider dark matter consisting of two (or more) states that have a small mass splitting. The exothermic (down)scattering of the heavier state to the lighter state can fit the data for keV mass splittings. Finally, we consider a subcomponent of dark matter that is accelerated by scattering off cosmic rays, finding that dark matter interacting though an $$ \mathcal{O} $$ O (100 keV)-mass mediator can fit the data. The cross sections required in this scenario are, however, typically challenged by complementary probes of the light mediator. Throughout our study, we implement an unbinned Monte Carlo analysis and use an improved energy reconstruction of the XENON1T events.

Section: Jhep01(2021)178mentioning

confidence: 99%

Exploring new physics with O(keV) electron recoils in direct detection experiments

Bloch

Caputo

Essig

et al. 2021

103

“…Besides, there are also other rich phenomenons JHEP04(2021)269 in this model. For example, it is possible to explain the muon g − 2 anomaly [24] and XENON1T excess [28,[31][32][33][34][35][36][37]. Last but not least, the excited DM state can naturally become long-lived and leave displaced vertex inside detectors after it has been produced such that these novel signatures can be searched for at colliders.…”

Section: Jhep04(2021)269mentioning

confidence: 99%

Exploring properties of long-lived particles in inelastic dark matter models at Belle II

Kang¹,

Ko²,

Lu³

2021

The inelastic dark matter model is one kind of popular models for the light dark matter (DM) below O(1) GeV. If the mass splitting between DM excited and ground states is small enough, the co-annihilation becomes the dominant channel for thermal relic density and the DM excited state can be long-lived at the collider scale. We study scalar and fermion inelastic dark matter models for $$ \mathcal{O} $$ O (1) GeV DM at Belle II with U(1)D dark gauge symmetry broken into its Z2 subgroup. We focus on dilepton displaced vertex signatures from decays of the DM excited state. With the help of precise displaced vertex detection ability at Belle II, we can explore the DM spin, mass and mass splitting between DM excited and ground states. Especially, we show scalar and fermion DM candidates can be discriminated and the mass and mass splitting of DM sector can be determined within the percentage of deviation for some benchmark points. Furthermore, the allowed parameter space to explain the excess of muon (g− 2)μ is also studied and it can be covered in our displaced vertex analysis during the early stage of Belle II experiment.

“…For a small gauge kinetic mixing in eq. (2.1), that is, ξ 1, the Z interactions to the SM are approximated [6,22] by…”

Section: Jhep04(2021)251mentioning

confidence: 99%

“…As discussed in the previous section, in the presence of flavor violation in the dark sector, dark mesons get split masses and their mixings give rise to Z gauge interactions changing between dark mesons. As far as m π 10 MeV, we can ignore the velocity of the bound electrons in Xenon atoms [6], so we assume that this is the case in our discussion.…”

Section: Dark Mesons and Xenon1t Electron Recoilmentioning

confidence: 99%

“…Exothermic dark matter has drawn new attention in this regard, due to the fact that a heavier component dark matter scatters off electron down to a lighter component dark matter [2][3][4][5], producing the recoil energy of electron peaked at the mass splitting between two components, even for the standard Maxwellian distribution of dark matter velocity. Pseudo-Dirac fermion dark matter [6] or complex scalar dark matter [7] with a dark U(1) symmetry have been proposed to explain the XENON1T excess. In these scenarios for exothermic dark matter, it is common to take dark matter and mediator particles to be light below GeV scale [8][9][10][11][12], belonging to the category that has been of growing interest in recent years as alternatives to WIMP dark matter.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exothermic dark mesons in light of electron recoil excess at XENON1T

Choi

Lee

Zhu

2021

Self Cite

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.