An appealing framework for dark matter is provided by light hidden sectors, below the electroweak scale, feebly coupled to the Standard Model via light mediators. We consider a minimal, predictive model where both the dark matter and the mediator are vector bosons, and have the same mass. The portal between the dark sector and the Standard Model is provided by a kinetic mixing between the dark gauge symmetry, SU(2) , and the hypercharge, U(1) , induced by a dimension-six operator. The dark-matter candidates, $\textit{X}$ , are charged under a custodial symmetry and therefore stable, while the mediator is a massive dark photon, $\textit{Z}$ , mixing with the photon and the $\textit{Z}$. We show how the observed dark-matter abundance can be reproduced via freeze-out or freeze-in, through either the kinetic mixing or the dark gauge interaction. We also analyse dark 3-to-2 annihilations, that can become dominant in model variations with $\textit{Z}$ heavier than $\textit{X}$ . We confront our relic-density predictions with current and projected experimental, astrophysical and cosmological bounds on the model parameter space, highlighting the correlation between the dark-photon and dark-matter phenomenologies.

Brazil

Ana Foguel

Renata Funchal

France

Michele Frigerio

Vector dark matter with non-abelian kinetic mixing

The scattering of extremely energetic cosmic rays with both cosmic microwave background and extragalactic background light, can produce 𝒪(10 eV) neutrinos, known as cosmogenic neutrinos. These neutrinos are the only messengers from the extreme cosmic accelerators that can reveal the origin of the most energetic cosmic rays. Consequently, much effort is being devoted to achieving their detection. In particular, the GRAND project aims to observe the $\textit{ν}$ and $$ {\overline{\nu}}_{\tau } $$ components of the cosmogenic neutrino flux in the near future using radio antennas. In this work, we investigate how the detection of cosmogenic neutrinos by GRAND can be used to probe beyond the Standard Model physics. We identify three well-motivated scenarios which induce distinct features in the cosmogenic neutrino spectrum at Earth: neutrino self-interactions mediated by a light scalar ($\textit{ν}$SI), pseudo-Dirac neutrinos (PD$\textit{ν}$) and neutrinos scattering on ultra-light Dark Matter ($\textit{ν}$DM). We show these scenarios can be tested by GRAND, using 10 years of cosmogenic neutrino data, in a region of parameter space complementary to current experiments. For the $\textit{ν}$SI model„ we find that GRAND can constrain the coupling to $\textit{ν}$ in the range [10 , 10 ] for a scalar with mass in the range 0.1 to 1 GeV. For PD$\textit{ν}$, we find that GRAND is sensitive to sterile-active mass squared splitting in the range [10 , 10 ] eV . Finally, for the $\textit{ν}$DM model, assuming a heavy mediator, GRAND can do substantially better than the current limits from other available data. These results rely on the fact that the actual cosmogenic flux is around the corner, not far from the current IceCube limit.

Luighi Leal

Spain

Daniel Naredo-Tuero

Cosmogenic neutrinos as probes of new physics

Despite the robust cosmological and astrophysical evidence confirming the existence of a non-baryonic matter component in the Universe, the underlying nature of Dark Matter (DM) remains a mystery. Among the several possible scenarios, light DM candidates thermally produced in the early Universe are especially interesting, since their abundance could be set via the standard freeze-out mechanism. Additionally, new light states can present a rich phenomenology and are attracting increasing attention due to recent experimental capabilities to probe dark sectors with feeble interactions. In particular, inelastic DM (iDM) candidates are an appealing option, since they can avoid cosmic microwave background (CMB) radiation bounds as well as indirect and direct detection searches. Although such models have been intensively studied in the literature, the usual scenario is to consider a secluded dark photon mediator. In this work, we consider the case of iDM with general vector mediators and explore the consequences of such a choice in the relic density computation, as well as for the cosmological and experimental bounds. We examine models with couplings to baryon and lepton number and show new viable parameter regions for inelastic dark matter models. Especially, anomaly-free gauge groups with non-universal couplings to leptons open new windows of the parameter space for thermal dark matter yet unexplored by experiments. We also provide a numerical Python library to compute the relic densities for user-defined gauge charges.

Peter Reimitz

Unlocking the inelastic Dark Matter window with vector mediators

In this paper we study the present and future sensitivities of the rare meson decay facilities KOTO, LHCb and Belle II to a light dark sector of the minimal dark abelian gauge symmetry where a dark Higgs S and a dark photon Z  D  have masses ≲ 10 GeV. We have explored the interesting scenario where S can only decay to a pair of Z  D ’s and so contribute to visible or invisible signatures, depending on the life-time of the latter. Our computations show that these accelerator experiments can access the dark Higgs (mass and scalar mixing) and the dark photon (mass and kinetic mixing) parameters in a complementary way. We have also discussed how the CMS measurement of the SM Higgs total decay width and their limit on the Higgs invisible branching ratio can be used to extend the experimental reach to dark photon masses up to ~ 10 GeV, providing at the same time sensitivity to the gauge coupling associated with the broken dark abelian symmetry.

Gabriel Salla

(In)Visible signatures of the minimal dark abelian gauge sector

Abelian U(1) gauge group extensions of the Standard Model represent one of the most minimal approaches to solve some of the most urgent particle physics questions and provide a rich phenomenology in various experimental searches. In this work, we focus on baryophilic vector mediator models in the MeV-to-GeV mass range and, in particular, present, for the first time, gauge vector field decays into almost arbitrary hadronic final states. Using only very little theoretical approximations, we rigorously follow the vector meson dominance theory in our calculations. We study the effect on the total and partial decay widths, the branching ratios, and not least on the present (future) experimental limits (reach) on (for) the mass and couplings of light vector particles in different models. We compare our results to current results in the literature. Our calculations are publicly available in a python package to compute various vector particle decay quantities in order to describe leptonic as well as hadronic decay signatures for experimental searches.

A robust description of hadronic decays in light vector mediator models

Neutrino trident scattering is a rare Standard Model process where a charged-lepton pair is produced in neutrino-nucleus scattering. To date, only the dimuon final-state has been observed, with around 100 total events, while the other channels are as yet unexplored. In this work, we compute the trident production cross section by performing a complete four-body phase space calculation for different hadronic targets. This provides a correct estimate both of the coherent and the diffractive contributions to these cross sections, but also allows us to address certain inconsistencies in the literature related to the use of the Equivalent Photon Approximation in this context. We show that this approximation can give a reasonable estimate only for the production of dimuon final-states in coherent scattering, being inadmissible for all other cases considered. We provide estimates of the number and distribution of trident events at several current and future near detector facilities subjected to intense neutrino beams from accelerators: five liquid-argon detectors (SBND, μBooNE, ICARUS, DUNE and νSTORM), the iron detector of T2K (INGRID) and three detectors made of composite material (MINOS, NOνA and MINERνA). We find that for many experiments, trident measurements are an attainable goal and a valuable addition to their near detector physics programme.

United Kingdom

Peter Ballett

Matheus Hostert

Silvia Pascoli

Yuber Perez-Gonzalez

Zahra Tabrizi

Neutrino trident scattering at near detectors

The detection of coherent neutrino-nucleus scattering by the COHERENT collaboration has set on quantitative grounds the existence of an irreducible neutrino background in direct detection searches of Weakly Interacting Massive Dark Matter candidates. This background leads to an ultimate discovery limit for these experiments: a minimum Dark Matter interaction cross section below which events produced by the coherent neutrino scattering will mimic the Dark Matter signal, the so-called neutrino floor. In this work we study the modification of such neutrino floor induced by non-standard neutrino interactions within their presently allowed values by the global analysis of oscillation and COHERENT data. By using the full likelihood information of such global analysis we consistently account for the correlated effects of non-standard neutrino interactions both in the neutrino propagation in matter and in its interaction in the detector. We quantify their impact on the neutrino floor for five future experiments: DARWIN (Xe), ARGO (Ar), Super-CDMS HV (Ge and Si) and CRESST phase III (CaWO4). Quantitatively, we find that non-standard neutrino interactions allowed at the 3σ level can result in an increase of the neutrino floor of up to a factor ∼ 5 with respect to the Standard Model expectations and impact the expected sensitivities of the ARGO, CRESST phase III and DARWIN experiments.

United States

M. Gonzalez-Garcia

Michele Maltoni

Neutrino discovery limit of Dark Matter direct detection experiments in the presence of non-standard interactions

We investigate the sensitivity of IceCube(-Gen2) to a scalar leptoquark scenario with couplings only to heavy quark flavors which may be connected to solving discrepancies in B-meson semileptonic decays. We take into account, for the first time, the non-negligible neutrino-gluon cross section induced by leptoquarks, and we systematically account for indirect and direct constraints which have been overlooked in previous studies. We conclude that IceCube(-Gen2) can only probe the light LQ regime, already disfavored by the combination of flavor physics constraints, electroweak precision data and the direct searches at the LHC.

Damir Bečirević

Boris Panes

Italy

Olcyr Sumensari

Seeking leptoquarks in IceCube

In Neutrinophilic Two Higgs Doublet Models, Dirac neutrino masses are obtained by forbidding a Majorana mass term for the right-handed neutrinos via a symmetry. We study a variation of such models in which that symmetry is taken to be a local U(1), leading naturally to the typical Lagrangian of the inverse seesaw scenario. The presence of a new gauge boson and of an extended scalar sector result in a rich phenomenology, including modifications to Z, Higgs and kaon decays as well as to electroweak precision parameters, and a pseudoscalar associated to the breaking of lepton number.

Enrico Bertuzzo

Pedro Machado

A neutrinophilic 2HDM as a UV completion for the inverse seesaw mechanism

We discuss the effect of Beyond the Standard Model charged current interactions on the detection of the Cosmic Neutrino Background by neutrino capture on tritium in a PTOLEMY-like detector. We show that the total capture rate can be substantially modified for Dirac neutrinos if scalar or tensor right-chiral currents, with strength consistent with current experimental bounds, are at play. We find that the total capture rate for Dirac neutrinos, Γ D BSM , can be between 0.3 to 2.2 of what is expected for Dirac neutrinos in the Standard Model, Γ D SM , so that it can be made as large as the rate expected for Majorana neutrinos with only Standard Model interactions. A non-negligible primordial abundance of right-handed neutrinos can only worsen the situation, increasing Γ D BSM by 30 to 90%. On the other hand, if a much lower total rate is measured than what is expected for Γ D SM , it may be a sign of new physics.