This study reanalyzes the detection prospects of dark matter (DM) annihilation signals in the Galactic Center, focusing on velocity-dependent dynamics within a spike density near the supermassive black hole (Sgr A⋆). We investigate three annihilation processes — p-wave, resonance, and forbidden annihilation — under semi-relativistic velocities, leveraging gamma-ray data from Fermi and DAMPE telescopes. Our analysis integrates a fermionic DM model with an electroweak axion-like particle (ALP) portal, exploring annihilation into two or four photons. Employing a comprehensive six-dimensional integration, we precisely calculate DM-induced gamma-ray fluxes near Sgr A⋆, incorporating velocity and positional dependencies in the annihilation cross-section and photon yield spectra. Our findings highlight scenarios of resonance and forbidden annihilation, where the larger ALP-DM-DM coupling constant C  aχχ  can affect spike density, potentially yielding detectable gamma-ray line spectra within Fermi and DAMPE energy resolution. We set upper limits for C  aχχ  across these scenarios, offering insights into the detectability and spectral characteristics of DM annihilation signals from the Galactic Center.

China

Meiwen Yang

Zhi-Qi Guo

Xiao-Yi Luo

Zhao-Qiang Shen

Zi-Qing Xia

Chih-Ting Lu

Yue-Lin Tsai

Yi-Zhong Fan

Searching accretion-enhanced dark matter annihilation signals in the Galactic Centre

This study explores a minimal renormalizable dark matter (DM) model, incorporating a sub-GeV Majorana DM and a singlet scalar particle ϕ. Using scalar and pseudo-scalar interactions (couplings c  s  and c  p ), we investigate implications for DM detection, considering s-wave, p-wave, and combined (s+p wave) contributions in DM annihilation cross-section, as well as loop-correction contributions to DM-nucleon elastic scattering. Identifying a broad parameter space (10 MeV &lt; m  χ  ≲ m  ϕ ) within the 2σ allowed region, we explore scenarios (|c  s | ≫ |c  p |, |c  s | ≪ |c  p |, and |c  s | ≈ |c  p |). We find that (i) a non-zero pseudo-scalar coupling alleviates direct detection constraints as a comparison with the previous pure scalar coupling case; (ii) CMB observations set stringent limits on pseudo-scalar interaction dominant cases, making s-wave annihilation viable only for m  χ  &gt; 1 GeV; (iii) the preferred ϕ-resonance region can be tested in the future indirect detection experiments, such as e-ASTROGAM.

Yu-Tong Chen

Japan

Shigeki Matsumoto

Tian-Peng Tang

Lei Wu

Light thermal dark matter beyond p-wave annihilation in minimal Higgs portal model

The Galactic center gamma-ray excess (GCE) is a long-standing unsolved problem. One of candidate solutions, the dark matter (DM) annihilation, has been recently tested with other astrophysical observations, such as AMS-02 electron-positron spectra, Fermi Dwarf spheroidal galaxies gamma-ray data, and so on. By assuming that the DM particles annihilate purely into a normal charged fermion pair, Di Mauro and Winkle (2021) claimed that only a muon-pair is compatible with the null detection of all the corresponding astrophysical measurements and can explain GCE simultaneously. On the other hand, a muonphilic DM model may also lead to a signal in the recent Fermilab muon g − 2 measurement or be constrained by the latest PandaX-4T limit. In this work, we comprehensively study interactions between DM and muon, including various combinations of DM and mediator spins. In agreement with GCE (not only 2μ but also 4μ final states), we test these interactions against all the thermal DM constraints. Our results show that only the parameter space near the resonance region of mediator can explain GCE and relic density simultaneously, and larger parameter spaces are still allowed if other poorly-known systematic uncertainties are included. Regardless of the DM spin, only the interactions with the spin-0 mediator can explain the recent muon g − 2 excess on top of GCE, relic density, and other DM and mediator constraints.

Murat Abdughani

Muonphilic dark matter explanation of gamma-ray galactic center excess: a comprehensive analysis

The null signal from collider and dark matter (DM) direct detector experiments makes the interaction between DM and visible matter too small to reproduce the correct relic density for many thermal DM models. The remaining parameter space indicates that two almost degenerated states in the dark sector, the inelastic DM scenario, can co-annihilate in the early universe to produce the correct relic density. Regarding the direct detection of the inelastic DM scenario, the virialized DM component from the nearby halo is nonrelativistic and not able to excite the DM ground state, even if the relevant couplings can be considerable. Thus, a DM with a large mass splitting can evade traditional virialized DM direct detection. In this study, we connect the concept of cosmic-ray accelerated DM in our Milky Way and the direct detection of inelastic scattering in underground detectors to explore spectra that result from several interaction types of the inelastic DM. We find that the mass splitting   <math> <mi>δ</mi> <mo>&lt;</mo> <mi>O</mi> <mfenced> <mrow> <mn>1</mn> <mspace width="0.25em"></mspace> <mi>GeV</mi> </mrow> </mfenced> </math>  $$ \delta &lt;\mathcal{O}\left(1\ \mathrm{GeV}\right) $$  can still be reachable for cosmic ray accelerated DM with mass range 1 MeV &lt;   <math> <msub> <mi>m</mi> <msub> <mi>χ</mi> <mn>1</mn> </msub> </msub> </math>  $$ {m}_{\chi_1} $$  &lt; 100 GeV and sub-GeV light mediator using the latest PandaX-4T data, even though we conservatively use the astrophysical parameter (effective length) D eff = 1 kpc.

Jie-Cheng Feng

Xian-Wei Kang

Feng-Shou Zhang

Revising inelastic dark matter direct detection by including the cosmic ray acceleration

Recently, we have witnessed two hints of physics beyond the standard model: a 3.3σ local excess (  <math> <msub> <mi>M</mi> <msub> <mi>A</mi> <mn>0</mn> </msub> </msub> </math>  $$ {M}_{A_0} $$  = 52 GeV) in the search for H 0 → A 0 A 0 → b   <math> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math>  $$ \overline{b} $$  μ  +  μ  −  and a 4.2σ deviation from the SM prediction in the (g − 2) μ  measurement. The first excess was found by the ATLAS collaboration using 139 fb −1 data at   <math> <msqrt> <mi>s</mi> </msqrt> </math>  $$ \sqrt{s} $$  = 13 TeV. The second deviation is a combination of the results from the Brookhaven E821 and the recently reported Fermilab E989 experiment. We attempt to explain these deviations in terms of a renormalizable simplified dark matter model. Inspired by the null signal result from dark matter (DM) direct detection, we interpret the possible new particle, A 0, as a pseudoscalar mediator connecting DM and the standard model. On the other hand, a new vector-like muon lepton can explain these two excesses at the same time while contributing to the DM phenomenology.

South Korea

Taiwan

Raymundo Ramos

Shedding light on dark matter with recent muon (g − 2) and Higgs exotic decay measurements

We perform a comprehensive analysis for the light scalar dark matter (DM) in the Inert two Higgs doublet model (i2HDM) with compressed mass spectra, small mass splittings among three ℤ odd particles — scalar , pseudo-scalar , and charged Higgs . In such a case, the co-annihilation processes play a significant role to reduce DM relic density. As long as a co-annihilation governs the total interaction rate in the early universe, a small annihilation rate is expected to reach a correct DM relic density and its coupling between DM pair and Higgs boson shall be tiny. Consequently, a negligible DM-nucleon elastic scattering cross section is predicted at the tree-level. In this work, we include the one-loop quantum corrections of the DM-nucleon elastic scattering cross section. We found that the quartic self-coupling between ℤ odd particles indeed contributes the one-loop quantum correction and behaves non-trivially for the co-annihilation scenario. Interestingly, the parameter space, which is allowed by the current constraints considered in this study, can predict the DM mass and annihilation cross section at the present compatible with the AMS-02 antiproton excess. The parameter space can be further probed at the future high luminosity LHC.

Van Tran

Confronting dark matter co-annihilation of Inert two Higgs Doublet Model with a compressed mass spectrum

We study the constraints on the new parameters in the gauge sector of gauged two Higgs doublet model using the electroweak precision test data collected from the Large Electron Positron Collider (LEP) at and off the Z-pole as well as the current Drell-Yan and high-mass dilepton resonance data from the Large Hadron Collider (LHC). Impacts on the new parameters by the projected sensitivities of various electroweak observables at the Circular Electron Positron Collider (CEPC) proposed to be built in China are also discussed. We also clarify why the Stueckelberg mass M  Y  for the hypercharge U(1) Y  is set to be zero in the model by showing that it would otherwise lead to the violation of the standard charge assignments for the elementary quarks and leptons when they couple to the massless photon.

Cheng-Tse Huang

Tzu-Chiang Yuan

Consistency of gauged two Higgs doublet model: gauge sector

A light fermionic weakly interacting massive particle (WIMP) dark matter is investigated by studying its minimal renormalizable model, where it requires a scalar mediator to have an interaction between the WIMP and standard model particles. We perform a comprehensive likelihood analysis of the model involving the latest but robust constraints and those will be obtained in the near future. In addition, we pay particular attention to properly take the kinematically equilibrium condition into account. It is shown that near-future experiments and observations such as low-mass direct dark matter detections, flavor experiments and CMB observations play important roles to test the model. Still, a wide parameter region will remain even if no WIMP and mediator signals are detected there. We also show that precise Higgs boson measurements at future lepton colliders will significantly test this remaining region.

Po-Yan Tseng

Light fermionic WIMP dark matter with light scalar mediator

In this paper we study sneutrino dark matter in a recently proposed supersymmetric electroweak-scale inverse seesaw model, in which the majority of the sneutrino dark matter particle is a mixture of the right-handed sneutrino Ñ  c  and the singlet field  <math><mover><mi>S</mi><mo>˜</mo></mover></math> $$ \tilde{S} $$. The scalar field X responsible for the generation of neutrino masses can simultaneously play a crucial role for sneutrino annihilation in the early Universe via the pseudoscalar mediator A  X  into neutrinos. We focus here on the dominant annihilation channels and provide all the formulas together with analytic estimates in order to identify the relevant parameters. Furthermore, we show that the direct detection scattering cross section is many orders of magnitude below the current limits, and estimate the indirect detection annihilation rate, which is only a few orders of magnitude below the current limits.

Jung Chang

Kingman Cheung

Hiroyuki Ishida

Martin Spinrath

Sneutrino dark matter via pseudoscalar X-funnel meets inverse seesaw

Recently a gauged two Higgs doublet model, in which the two Higgs doublets are embedded into the fundamental representation of an extra local $$SU(2)_H$$ <math><mrow><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mi>H</mi></msub></mrow></math>  group, was constructed. Both the new gauge bosons $$Z^\prime $$ <math><msup><mi>Z</mi><mo>′</mo></msup></math>  and $$W^{\prime (p,m)}$$ <math><msup><mi>W</mi><mrow><mo>′</mo><mo>(</mo><mi>p</mi><mo>,</mo><mi>m</mi><mo>)</mo></mrow></msup></math>  are electrically neutral. While $$Z^\prime $$ <math><msup><mi>Z</mi><mo>′</mo></msup></math>  can be singly produced at colliders, $$W^{\prime (p,m)}$$ <math><msup><mi>W</mi><mrow><mo>′</mo><mo>(</mo><mi>p</mi><mo>,</mo><mi>m</mi><mo>)</mo></mrow></msup></math> , which is heavier, must be pair produced. We explore the constraints of $$Z^\prime $$ <math><msup><mi>Z</mi><mo>′</mo></msup></math>  using the current Drell–Yan type data from the Large Hadron Collider. Anticipating optimistically that $$Z^\prime $$ <math><msup><mi>Z</mi><mo>′</mo></msup></math>  can be discovered via the clean Drell–Yan type signals at a high luminosity upgrade of the collider, we explore the detectability of extra heavy fermions in the model via the two leptons/jets plus missing transverse energy signals from the exotic decay modes of $$Z^\prime $$ <math><msup><mi>Z</mi><mo>′</mo></msup></math> . For the $$W^{\prime (p,m)}$$ <math><msup><mi>W</mi><mrow><mo>′</mo><mo>(</mo><mi>p</mi><mo>,</mo><mi>m</mi><mo>)</mo></mrow></msup></math>  pair production in a future 100 TeV proton–proton collider, we demonstrate certain kinematical distributions for the two/four leptons plus missing energy signals have features distinguishable from the Standard Model background. In addition, comparisons of these kinematical distributions between the gauged two Higgs doublet model and the littlest Higgs model with T-parity, the latter of which can give rise to the same signals with competitive if not larger cross sections, are also presented.

Germany

Denmark

Wei-Chih Huang

Signals of new gauge bosons in gauged two higgs doublet model