The article describes Boltzmann equations for a potential case of multi-particle dark matter with symmetric and asymmetric dark matter components in a model-independent approach. We focus on the specific scenario where one of the DM candidates remains completely invisible, having only hidden sector interactions with the other dark matter constituent referred to as “dark annihilation”. The possible effect of non-standard expansion of the universe on the dark matter abundance is also taken into account.

India

Amit Dutta Banik

Exploring the dark annihilation: Multi-component asymmetric and symmetric dark matter

A generalized Amit-Roginsky vector model in flat space is obtained as the effective dynamics of pertubations around a classical solution of the Boulatov group field theory for 3D Euclidean quantum gravity, extended to include additional matter degrees of freedom. By further restricting the type of perturbations, the original Amit-Roginsky model can be obtained. This result suggests a general link (and possibly a unified framework) between two types of tensorial quantum field theories; on one hand quantum geometric group field theories and tensorial models for random geometry, and on the other hand melonic-dominated vector and tensorial models in flat space, such as the Amit-Roginsky model and the Sachdev-Ye-Kitaev model.

France

Victor Nador

Germany

Daniele Oriti

Xiankai Pang

Romania

Adrian Tanasa

Yi-Li Wang

Generalized Amit-Roginsky model from perturbations of 3D quantum gravity

If multiple thermal weakly interacting massive particle (WIMP) dark matter candidates exist, then their capture and annihilation dynamics inside a massive star such as Sun could change from conventional method of study. With a simple correction to time evolution of dark matter (DM) number abundance inside the Sun for multiple dark matter candidates, significant changes in DM annihilation flux depending on annihilation, direct detection cross-section, internal conversion and their contribution to relic abundance are reported in present work.

A solar investigation of multicomponent dark matter

We discuss how a post-inflationary reheating phase characterized by a nonstandard multiple scalar field cosmology can change the thermal history of the Universe, affecting minimal high-scale leptogenesis. In particular, we explore a class of models where a set of scalar fields in a brane-inspired dynamical scenario modifies the Boltzmann equations concerning standard leptogenesis. The produced lepton asymmetry <math><msub><mi>Y</mi><mi>L</mi></msub></math>, due to the decays of heavy Majorana right-handed neutrinos responsible for generating Standard Model neutrino masses via the type-I seesaw, is affected as well. In particular, both an enhancement and a reduction of <math><msub><mi>Y</mi><mi>L</mi></msub></math> can be obtained, depending on the values of the (new) involved parameters and on the number of additional scalar fields.

Italy

Alessandro Di Marco

Poland

Anish Ghoshal

Gianfranco Pradisi

Minimal leptogenesis in brane-inspired cosmology

We perform a detailed study of scalar dark matter with triplet Higgs extensions of the Standard Model in order to explain the cosmic ray electron and positron excesses reported by AMS-02 and DAMPE. A detailed analysis of the AMS-02 positron excess reveals that for different orderings (normal, inverted, and quasi-degenerate) of neutrino mass, the hybrid triplet Higgs portal framework is more favored with respect to the single triplet Higgs portal for TeV scale dark matter. We also show that the resonant peak and continuous excess in DAMPE cosmic ray data can be well explained with the hybrid triplet Higgs portal dark matter when a dark matter sub-halo nearby is taken into account.

China

Shao-Long Chen

Ze-Kun Liu

Confronting cosmic ray electron and positron excesses with hybrid triplet Higgs portal dark matter  

We revisit dark matter annihilation as an explanation of the positron excess reported recently by the AMS-02 satellite-borne experiment. To this end, we propose a particle dark matter model by considering a two Higgs doublet model (2HDM) extended with an additional singlet boson and a singlet fermion. The additional (light) boson mixes with the pseudoscalar inherent in the 2HDM, and the singlet fermion, which is the dark matter candidate, annihilates via this bosonic portal. The dark matter candidate is made leptophilic by choosing the lepton-specific 2HDM and a suitable high value of <math><mi>tan</mi><mi>β</mi></math>. We identify the model parameter space which explains the muon g-2 anomaly while evading the experimental constraints. After establishing the viability of the singlet fermion to be a dark matter candidate, we calculate the positron excess produced from its annihilation to the light bosons which primarily decay to muons. Incorporating the Sommerfeld effect caused by the light mediator and an appropriate boost factor, we find that our proposed model can satisfactorily explain the positron fraction excess as well as the positron spectrum data reported by the AMS-02 experiment.

Sayan Ghosh

South Korea

Eung Jin Chun

Debasish Majumdar

Leptophilic-portal dark matter in the light of AMS-02 positron excess

We explore the phenomenology of the Georgi-Machacek model extended with two Higgs doublets and vector fermion doublets invariant under <math><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mrow><mi>L</mi></mrow></msub><mo>×</mo><mi>U</mi><msub><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow><mrow><mi>Y</mi></mrow></msub><mo>×</mo><msub><mrow><mi>Z</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>×</mo><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math>. The <math><msub><mrow><mi>Z</mi></mrow><mrow><mn>4</mn></mrow></msub></math> symmetry is broken spontaneously while the imposed <math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math> symmetry forbids triplet fields to generate any vacuum expectation value and leading to an inert dark sector providing a viable candidate for dark matter and generate neutrino mass radiatively. Another interesting feature of the model is leptogenesis arising from decay of vector-like fermions. A detailed study of the model is pursued in search for available parameter space consistent with the theoretical and experimental observations for dark matter, neutrino physics, flavor physics, matter-antimatter asymmetry in the Universe.

Common origin of radiative neutrino mass, dark matter and leptogenesis in scotogenic Georgi-Machacek model

We propose a two component dark matter setup by extending the Standard Model with a singlet and a hyperchargeless triplet scalars, each of them being odd under different <math><msub><mi>Z</mi><mn>2</mn></msub></math> symmetries. We observe that the interconversion between the two dark matter components allow a viable parameter space where masses of both the dark matter candidates can be below TeV, even though their individual contribution to single component dark matter rules out any such sub-TeV dark matter. We find that a lighter mass of the neutral component of the scalar triplet, playing the role of one dark matter component, compared to the singlet one is favored. In addition, the setup is shown to make the electroweak vacuum absolutely stable till the Planck scale, thanks to Higgs portal coupling with the scalar dark matter components.

Rishav Roshan

Arunansu Sil

Two component singlet-triplet scalar dark matter and electroweak vacuum stability

Rare B meson decays offer an opportunity to probe a light hidden <math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math> boson. In this work we explore a new channel <math><msub><mrow><mi>B</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>→</mo><mi>γ</mi><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math> (<math><mi>q</mi><mo>=</mo><mi>d</mi><mo>,</mo><mi>s</mi></math>) followed by a cascade decay of <math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math> into an invisible (neutrino or dark matter) or charged lepton pair <math><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>−</mo></mrow></msup></math> (<math><mi>ℓ</mi><mo>=</mo><mi>e</mi><mo>,</mo><mi>μ</mi></math>). The study is based on a simplified effective model where the down quark sector has tiny flavor-changing neutral current couplings with <math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math>. For the first time, we calculate <math><mrow><mi>BR</mi></mrow><mo>(</mo><msub><mrow><mi>B</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>→</mo><mi>γ</mi><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>)</mo></math> at the leading power of <math><mn>1</mn><mo>/</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>b</mi></mrow></msub></math> and <math><mn>1</mn><mo>/</mo><msub><mrow><mi>E</mi></mrow><mrow><mi>γ</mi></mrow></msub></math>. Confronting with the strong constraints from semi-invisible decays of B meson, we find that the branching ratio for <math><msub><mrow><mi>B</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>→</mo><mrow><mi>invisible</mi></mrow><mo>+</mo><mi>γ</mi></math> can be larger than its Standard Model background prediction, leaving a large room for new physics, in particular for light dark matter. Additionally, the branching ratio for <math><msub><mrow><mi>B</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>→</mo><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>γ</mi></math> can also be sizable when the corresponding flavor violating <math><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></math> coupling to quarks is of the axial-vector type. On the other hand, the predicted branching ratios of <math><msub><mrow><mi>B</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>→</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>γ</mi></math> and <math><msub><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>→</mo><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>γ</mi></math> are severely constrained by the experimental measurements.

Zhaofeng Kang

Qin Qin

Yoshihiro Shigekami

Signatures of a flavor changing ′ Boson in → ′

We present a study of singlet-doublet vectorlike leptonic dark matter (DM) in the framework of the two-Higgs-doublet model (2HDM), where the dark sector is comprised of one doublet and one singlet vectorlike fermion (VLF). The DM, that arises as an admixture of the neutral components of the VLFs, is stabilized by an imposed discrete symmetry <math><msubsup><mi>Z</mi><mn>2</mn><mo>′</mo></msubsup></math>. We test the viability of the DM candidate in the light of observations from Planck and recent limits on spin-independent direct detection experiments and search for its possible collider signals. In addition, we also look for the stochastic gravitational wave (GW) signatures resulting from strong first-order phase transition due to the presence of the second Higgs doublet. The model thus offers a viable parameter space for a stable DM candidate that can be probed from direct search, collider, and GW experiments.