Seminars 2025-26

Abstract: The Belle and Belle II experiments have collected samples of e+e- collision data at centre-of-mass energies near the \Upsilon(4S) resonance. These data include low-multiplicity processes with constrained kinematics, which allow us to perform searches for dark sector particles in the mass range from a few MeV to 10 GeV. Using a 365/fb sample collected by Belle II, we search for inelastic dark matter and an associated dark higgs. Furthermore, we study rare B-meson decays that could be relevant for dark-sector particle searches. By analyzing 711/fb of Belle data, we search for an axion-like particle (ALP) that decays to \gamma \gamma in B meson decays, B \to K^{(*)} a (\to \gamma\gamma). With the same data set, we also search for feebly-interaction particles in B decays. In addition, we talk about recent results in the study of rare B-meson decays to final states involving a pair of neutrinos, B \to X_s \nu \bar{\nu}.

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Abstract: "Protostellar outflows are among the most striking signatures of ongoing star formation, playing a critical role in removing angular momentum, redistributing material, and processing the dust and gas within protostellar systems and their surrounding environments. With the unprecedented sensitivity of the James Webb Space Telescope (JWST), we can now spatially resolve deeply embedded regions around forming protostars across near- to mid-infrared wavelengths. This provides access to a rich suite of atomic fine-structure and molecular emission lines that trace the physical and chemical conditions of outflows, revealing their structure down to scales of tens of AU in nearby star-forming regions.

In this talk, I will first provide a brief overview of protostellar outflows and their role in the star formation process, highlighting insights from JWST and earlier observations, and pointing to some of the key open questions that remain. I will then present recently published work with JWST NIRSpec and MIRI IFUs that uses infrared emission lines from a protostellar outflow as a background light source to measure a wavelength-dependent dust attenuation curve through the surrounding envelope, the reservoir that feeds disks in the youngest protostars and sets the stage for planet formation. I will then discuss related projects that use JWST line diagnostics to study disks and outflows in several systems, with the goal of placing their emission in a broader star and planet formation context."

Abstract: Jets at colliders like the LHC are incredibly complicated to understand, both theoretically and experimentally. In this talk, I describe a general class of jet shape observables, based on the Energy-Mover’s-Distance and its variants, that can be used to distill the information inside jets in experimentally, computationally, and theoretically tractable ways. These observables probe the geometric properties of jets in a human-interpretable way and are in-principle calculable using perturbative QCD. I also briefly discuss how theoretical guarantees and priors such as IRC-safety can be baked into machine learning models and loss functions, and how they can also be used to study the shape of jets

Abstract: The problem of interpretability of machine learning architecture in particle physics has no agreed-upon definition, much less any proposed solution. In this talk, I present a first modest step toward these goals by proposing a definition and corresponding practical method for isolation and identification of relevant physical energy scales exploited by the machine. This is accomplished by smearing or averaging over all input events that lie within a prescribed metric energy distance of one another and correspondingly renders any quantity measured on a finite, discrete dataset continuous over the dataspace. In this framework, I will also discuss how scaling laws that relate compute resources to performance naturally arise, and how properties of the likelihood ratio for quark versus gluon jet discrimination are manifest.

Abstract: Over the past decades, high-energy experiments at the world's collider physics laboratories have unraveled many mysteries of our universe, and confirmed Quantum Field Theories as the leading theoretical framework for the description of elementary particles and their interactions. The Large Hadron Collider (LHC) and the Future Circular Collider (FCC) hold the potential to unlock the remaining secrets of the Higgs boson, in particular the form of its potential and the fate of our universe. Probing nature at the extreme energy and intensity of an LHC or FCC requires extraordinary investments from both experiment and theory. Connecting the two are computer simulations, which allow to convert the aesthetic beauty of a Lagrange density into observable predictions for experiments. This talk will discuss the development of such simulations at a level of precision needed to fully exploit the expected datasets available from the world's colliders on the 2040-2050 time scale.

Abstract: I show that extending the Standard Model with two axions and a dark vector-like confining gauge group can simultaneously account for both the observed dark matter abundance and the baryon asymmetry of the Universe - a step toward resolving the matter coincidence problem. Starting from a review of sphaleron dynamics, I derive both (i) the axion-induced contributions to fermion asymmetries and (ii) the back-reaction of these fermion asymmetries on axion-like fields, which manifests as a friction on the axions. This analysis clarifies why the minimal axiogenesis scenario cannot produce the correct dark matter and baryon abundances simultaneously. We then show that introducing a second axion and an additional vector-like dark confining sector - a natural infrared realization in the well-motivated axiverse frameworks - resolves this tension by providing a distinct source of friction in the axion dynamics. Finally, we discuss possible UV completions of this setup in extra-dimensional models of high-quality axions. Beyond its cosmological implications, this framework motivates searches for the QCD axion and predicts complementary Light-Shining-through-Wall signatures probing the second axion in the ~eV mass range.

Abstract: Determining the form of the Higgs potential is one of the most exciting challenges of modern particle physics. Higgs pair production directly probes the Higgs self-coupling and should be observed in the near future at the High-Luminosity LHC. We explore how to improve the sensitivity to physics beyond the Standard Model through per-event kinematics for di-Higgs events. In particular, we employ machine learning through simulation-based inference to estimate per-event likelihood ratios and gauge potential sensitivity gains from including this kinematic information. In terms of the Standard Model Effective Field Theory, we find that adding a limited number of observables can help to remove degeneracies in Wilson coefficient likelihoods and significantly improve the experimental sensitivity.

Abstract: Unexpected results from various short-baseline neutrino oscillation experiments have suggested the potential existence of a light sterile neutrino. Such a particle would affect the flux of muon neutrinos produced by accelerators in the GeV energy range; however, this attenuation has not been observed, leading to the so-called "3+1" neutrino puzzle. We have recently carried out a 3+1 sterile neutrino search using over 10 years of IceCube data of atmospheric muon neutrinos in the 0.5-100 TeV energy range. This study is unique as it explores sterile neutrinos at higher energies, testing their potential effects through both vacuum and matter-enhanced oscillations. In this seminar, I will present the latest findings from this analysis and discuss their implications within the framework of the 3+1 neutrino landscape.

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Abstract: The anomalous magnetic moment of the muon (aμ) provides a stringent test of the quantum nature of the Standard Model (SM) and its extensions. To probe beyond the SM physics, one needs to be able to subtract the SM contributions, which consists of a non-perturbative part, namely, the hadronic vacuum polarization (HVP) of the photon. The state ofthe art is to predominantly use two different methods to extract this HVP: lattice computation, and dispersion relation-based, data-driven method. Thus one can construct different forms of the ``aμ test" which compares the precise measurement of aμ to its theory prediction. Additionally, this opens the possibility for another subtle test, where these two ``theory" predictions themselves are compared against each other, which is denoted as the ``HVP-test". This test is particularly sensitive to hadronic scale new physics. Therefore, in this work, we consider a SM extension consisting of a generic, light (100 MeV−1 GeV) vector boson and study its impact on both tests. We develop a comprehensive formalism for this purpose. We find that in the case of data-driven HVP being used in the aμ test, the new physics contributions effectively cancel for a flavor-universal vector boson. As an illustration of these general results, we consider two benchmark models: i)~the dark photon (A′) and ii)~a gauge boson coupled to baryon-number (B). Using a combination of these tests, we are able to constrain the parameter space of B and A′, complementarity to the existing limits. As a spin-off, our preliminary analysis of the spectrum of invariant mass of 3π in events with ISR at the B− factories (BaBar, Belle) manifests the value of such a study in searching for B→3π decay,

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Abstract: The NuGraph architecture is an attention message-passing graph neural network designed to address the challenges of reconstructing particle interactions in Liquid Argon Time Projection Chambers, a detector technology utilized heavily in neutrino physics that offers sub-millimeter spatial resolution. This talk summarizes the NuGraph2 architecture, which was applied to beam neutrinos in the MicroBooNE detector, achieving 98% efficiency in removing cosmic background activity and 95% efficiency in semantically labelling energy depositions according to particle type. It then discusses active development work for the next-generation NuGraph3 architecture, introducing heterogeneous and hierarchical graph approaches to predict quantities at multiple conceptual scales, including event prediction, clustering, spacepoint reconstruction and vertex prediction, across multiple detector geometries, including beam neutrino and nucleon decay events at the Deep Underground Neutrino Experiment.

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Abstract: In addition to their scientific goals of studying neutrino interactions and oscillations, modern-day neutrino facilities offer new approaches for searching for beyond-the-Standard-Model physics. Typically, such searches are driven by the copious amount of SM mesons produced in the proton-proton interactions, where those SM mesons can decay into new BSM particles of interest. In this talk, I will highlight the complementary nature of the electromagnetic showers that proceed inside of the targets in producing new BSM particles, such as dark photons and leptophilic gauge bosons. In doing so, I will demonstrate a new purpose-built tool, PETITE, designed for phenomenological studies of dark sectors in these environments.

Abstract: In this talk, we will discuss a few recent studies that use in situ measurement data from the gas giant Jupiter to test new physics. In these cases, the planet is a huge baryonic detector hanging in the outer solar system. In the first part, we will examine how data from Jupiter missions might help us learn more about dark matter. Jupiter's gravity could trap dark matter particles, producing detectable signals in the form of relativistic charged particle flow trapped in the magnetosphere. Later on, we will examine how to use Jupiter data to constrain long-range new physics effects. Examples include a light dark photon mixing with the SM photon or a fifth force mediator. In the former case, the magnetic field survey data is used to reconstruct one of Jupiter's most precise magnetic field models. Violations of the Maxwell equations suggest the presence of new physics around the typical scale of the Jovian system. In the second case, Juno's motion around Jupiter can be used to search for deviations from gravity and, thus, possible "fifth forces."

Abstract: The associated production of Higgs bosons at the electroweak scale offers an interesting window into new physics. This type of search benefits from a low SM background and enhanced sensitivity to new physics. Recently, statistically significant excesses have been observed by ATLAS in associated di-photon production (γγ + X) at around 152 GeV invariant mass of di-photons in the sidebands of SM Higgs analyses, which are compatible with associated production mechanisms for new Higgs bosons, such as Drell-Yan processes. In this context, I will discuss how such excesses can be explained within different new physics scenarios, such as a real Higgs triplet and the general aligned 2HDM.

Abstract: The Dark Energy Spectroscopic Instrument (DESI) collaboration is conducting a five-year redshift survey of 40 million extra-galactic sources over 14,000 square degrees of the northern sky up to the redshift of 4 with the Mayall 4-meter telescope at Kitt Peak National Laboratory. One of its primary goals is to measure the cosmic expansion history precisely and accurately through the measurements of baryon acoustic oscillations (BAO). In this talk, I will present the analysis of the DESI First Year Baryon Acoustic Oscillations using the distributions of galaxies and quasars over the redshift range of 0.1-2, the estimates of the relevant systematics, and their intriguing cosmological implications, including the time-evolving dark energy. If time permits, I will also present how we tackle observational systematics and probe inflation using galaxy surveys.

Abstract: The CCAT Observatory is building the Fred Young Submillimeter Telescope, a novel, high-throughput, 6-meter aperture telescope, to enable a wide range of new measurements. The science goals include line-intensity mapping of cosmic reionization, studying galaxy clusters, galactic magnetic fields, astronomical transients, and others. The Observatory is under construction at 5600 meters on Cerro Chajnantor, Chile. I highlight the complementarity of CCAT and related experiments, including recent results from the Atacama Cosmology Telescope and plans for Simons Observatory and CMB-S4. I detail CCAT's submillimeter measurement capabilities with its first high-throughput science receiver: Prime-Cam. This camera is designed to support over 10^5 kinetic inductance detectors and enable over 10x faster mapping speed than previous submillimeter observatories in submillimeter windows from 0.3 – 1.1 mm (280 – 850 GHz). We describe the project status, plans for early science observations starting in early 2026, and possible future line-intensity mapping upgrades to probe cosmology.

Abstract: The discovery of neutrino oscillations has opened a new chapter in particle physics. The observation of this phenomenon implies that neutrinos have non-zero masses, a property not accounted for in the Standard Model. The mechanism most widely-used to model neutrino oscillations uses a mixing matrix formalism, similar to the one in the quark sector. The probability of neutrino flavor oscillations depends on the size of the elements of this matrix, as well as the difference between the neutrino mass states. By measuring neutrinos from both natural and artificial sources, experiments over the past two decades have been able to measure the parameters describing neutrino oscillations with varying degrees of precision. The least well known oscillation parameters which remain to be probed are most accessible by using well understood and controlled neutrino beams from accelerators. Experiments which use this technique are sensitive, in particular, to the neutrino mass ordering and the complex CP-violating phase, dCP. The latter, in particular, determines whether CP symmetry is violated in the lepton sector, while the former will shed light on the neutrino mass ordering problem. The same experiments which tackle these challenges are well equipped to search for physics beyond the mixing matrix formalism.

Current long-baseline neutrino oscillation experiments (T2K and NOvA) measure oscillation parameters by comparing the evolution of the flavor composition in a pure (anti-)neutrino beam. The oscillation probability evolves as a function of neutrino energy. However, the neutrino energy spectrum measured in these experiments is also determined by the neutrino flux, detector efficiency effects, and the cross-section of neutrino interactions with the target nuclei. The latter introduce sources of systematic uncertainty, whose mis-modelling can severely bias neutrino oscillation parameter measurements. Of the three, the physics of neutrino interactions with matter represents the dominant source of systematic uncertainty.

Abstract: The abundance of metals in gas and stars is a powerful probe of the baryon cycle and galaxy formation histories. There is particular interest in using chemical abundances to probe the growth and formation of galaxies at high redshifts, when star-formation rates were higher and gas flows are thought to be stronger than in the local Universe. The majority of work in this area has focused on "one-dimensional" single-element analyses leveraging the oxygen abundance in the gas-phase ISM or the iron abundance in the stellar population as a tracer of bulk metallicity. Recently, the spectroscopic sensitivity of JWST's instrument suite has enabled the measurement of detailed chemical abundance patterns of several elements in individual high-redshift galaxies for the first time. I will discuss progress in understanding galaxy formation through the lens of chemical abundances both before and during the JWST era, and highlight some unexpected results that remain difficult to interpret.

Abstract: We present a paradigm where the (QCD) axion’s novel evolution, a rotation in field space, can address cosmological mysteries of the Universe. This dynamics may naturally arise as a result of quantum gravity effects and cosmic inflation but was overlooked in the extensive literature. This talk will explore the example where axion rotations contribute to axion dark matter through kinetic misalignment and can generate the observed baryon asymmetry of the Universe via axiogenesis. Remarkably, rich phenomenology automatically arises with sharp, distinct, and correlated predictions. These include specific axion properties more experimentally accessible than the conventional scenarios, unique gravitational wave signals, and correlated mass scales of supersymmetry and neutrinos. Thus far, axion rotations have added fuel to experimental efforts and paved new theory research avenues, opening up resolutions to the deepest cosmological mysteries with discoverable signatures.

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Abstract: Evidence that planet formation begins when protostars are less than 1 million years old continues to build. During this early phase of star formation, protostars and their disks are still embedded in (and feeding from) their natal environments while the first steps of planet formation occur. In particular, streamers---long and narrow infalling channels that funnel material to disks from their environments---have been predicted theoretically and serendipitously observed in a variety of tracers. Despite the growing evidence that the larger scale environments have an influence on the youngest planet-forming disks, my large PRODIGE survey, carried out with the NOEMA interferometer, is the currently the only large observing program specifically designed with streamers in mind.

In this talk I will outline my research program, which leverages the uniquely-wide swath of the electromagnetic spectrum sampled with PRODIGE, to probe how asymmetric infall from the larger-scale environment influence disk structure, temperature, and chemistry. These disk properties are directly connected to when planets form, where, and with what composition. Results from my observations pave the way for more-detailed observations targeting the initial conditions of planet formation with the premier ALMA interferometer, space-based infrared studies with JWST, and in a decade the ultra-high resolution ngVLA.

Abstract: An unprecedented array of new observational facilities will enable the detection of the earliest population of galaxies and black holes on extremely large scales, thereby providing key constraints on astrophysics and cosmology. These new facilities include, for instance, the James Webb Space Telescope (JWST), Euclid, the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx), the Nancy Grace Roman Space Telescope (Roman), and many more. To maximize the scientific return of these facilities, improved theoretical models, accurate generation of mock observations, and efficient statistical tools are all required. In this talk, I will discuss key challenges in analyzing outputs from large-scale surveys and provide several examples of how to improve modeling key observables and efficiently extract the maximum amount of information using a combination of numerical simulations and artificial intelligence.

Abstract: Though the use of machine learning (ML) is ubiquitous in astrophysics and cosmology, many still see the opacity of ML algorithms as a major issue to their scientific utility. One way of addressing this opacity is through an emerging trend in ML research of “teaching” ML algorithms physical laws and domain-specific knowledge. “Physics-informed machine learning” (PIML), asthis methodology is called, promises to produce better predictions and yield more interpretable algorithms. It does so by using physical principles in the training process and/or by using physical principles to guide the development of the neural network architecture. In this talk, I investigate two uses of PIML, each of which serves as a representative example of the two PIML methods. The first case study uses PIML to model the solar termination shock and the second uses PIML to predict the gravitational fields around small astronomical bodies. Though in both cases, PIML provides improvements in terms of the predictions and efficiency of ML algorithms, I argue that only in the second case does PIML offer any improvement in terms of the interpretability of the algorithms. I conclude with a discussion of the prospects for PIML methods going forward.

Abstract: Composite states occur over vast scales and play an important role in various domains of particle physics. In the first part I report on the recent development and application of non-relativistic QCD for the study of hadrons and multi-hadron systems in QCD and beyond. In particular, I will demonstrate how we obtain quantities such as binding energies, mass spectra and color scaling for heavy bound states. The techniques we employ are highly computationally efficient and thus can provide reliable estimates of properties of heavy baryons and multi-hadron systems, as well as dark baryons without the need for computationally intensive lattice QCD calculations. In the second part I introduce a chiral SU(15) gauge theory in which the SM quarks and leptons emerge as bound states of massless preons below a large confining scale. We show how under certain assumptions di-prebaryon bound states behave as Higgs fields and that proton-decay operators are likely induced at the compositeness scale. We find dominant exotic proton decay modes involving heavy right-handed neutrinos which could be observed using the Super-K or DUNE detectors. 

Abstract: The existence of Dark Matter is well established from astronomical observations, but its observation at particle colliders has remained elusive. The observation of the decay of an unknown, long-lived particle would be a compelling signature for many new-physics scenarios, including models for Dark Matter. Existing experiments have limited sensitivity to such decays, however, suggesting the need for new strategies.

The COmpact Detector for EXotics at LHCb (CODEX-b) would be a dedicated experiment near the LHCb detector at CERN's Large Hadron Collider (LHC), the only collider currently capable of producing Higgs Bosons. It would be located far from and transverse to the LHC beam line, and it would be shielded from the collision point, making it uniquely sensitive to long-lived particles produced in the decay of Higgs Bosons.

I here make the physics case for CODEX-b. I also present the status of its associated prototype, CODEX-β, currently under construction.

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Abstract: FASER is a small experiment at the LHC designed to search for new light, extremely weakly-interacting particles at CERN's Large Hadron Collider (LHC), as well as measure the interactions of Standard Model neutrinos. The experiment specifically targets new particles produced in the very forward direction in LHC's high energy proton-proton collisions, that subsequently decay to visible particles inside the FASER detector. The detector lies in wait 480 m downstream of the ATLAS interaction point, aligned with the beam collisions axis. During the seminar, I will present the FASER detector design, operational experiences and first results, which include new constraints on Dark Photons decaying to leptons, as well as observations of collider neutrino interactions in FASER.

Abstract: Event generators have become an essential part of understanding and testing the Standard Model of particle physics.  In this talk, I will introduce the Pythia8 event generator, explain how it is used in analyses, and comment on its evolution in face of new data.

Abstract: Starting in 2029, the High Luminosity LHC (HL-LHC) era will begin. Over its lifetime, the HL-LHC will increase the luminosity of the LHC by a factor of 10, allowing rare phenomena to be observed and measured for the first time. In order to perform these measurements, the LHC detectors are being upgraded. In this seminar, I will discuss the upgrade of the innermost system of the ATLAS detector - the inner tracker (Itk). I will describe how this detector will handle the harsh radiation environment of the HL-LHC and the ways in which it will further our physics goals. Finally, I will describe my role in building this new ATLAS inner tracker. .

Abstract: Direct decays of proposed heavy force mediator particles to standard model (SM) leptons have been excluded to high masses [1], but more exotic interactions and decays remain unexplored. I will present a search for one such exotic alternative: a leptophobic Z’ decaying via anomalons in proton-proton collisions at √s = 13 TeV with the Compact Muon Solenoid (CMS) Experiment. A leptophobic Z’ can decay via a pair of anomalons, new beyond the standard model (BSM) fermions introduced to cancel the gauge anomalies arising from the leptophobic condition. These heavy intermediate particles decay in turn to neutral SM bosons and lighter, stable anomalons that serve as a dark matter candidate. This analysis targets the Z(μμ)H(bb)+MET final state in a total  integrated luminosity of 137.6 fb-1 corresponding to the 2016-2018 data set. To search for the resonant Z’ production, this analysis employs Recursive Jigsaw Reconstruction (RJR), an iterative framework to reconstruct mass estimators in systems with invisible particles in the final state. I will present the expected sensitivity of this novel model and observable in a CMS search. Additionally, the assembly, installation, and commissioning of CMS Hadron Calorimeter Phase 1 upgrade will be discussed.

[1] CMS Collaboration. “Search for resonant and nonresonant new phenomena in high-mass dilepton final states at √s= 13 TeV”. In: Journal of High Energy Physics 2021.208 (June 2021). doi: 10.1007/JHEP07(2021)208. url: https: //doi.org/10.1007/JHEP07(2021)208. 

Abstract: Secondary anisotropies of the cosmic microwave background (CMB) are known to be remarkable probes of astrophysics and cosmology. The properties of free streaming CMB photons from the surface of last scattering are altered by their interaction with matter in the Universe carrying crucial information about the the epoch of reionisation and also the origin, growth, and evolution of structures. In this talk, I will discuss the potential of a couple of these secondary anisotropies, namely the kinematic and thermal Sunyaev-Zeldovich (SZ) effects, to shed light into some of the long-standing cosmological quests like the physics of reionisation and the properties of dark energy. I will also demonstrate the challenges posed by astrophysical foregrounds for the detection of these small-scale anisotropies and discuss strategies for mitigating them. Finally, I will discuss some of the ongoing work to constrain reionsation with kSZ using the South Pole Telescope and then present the prospects of SZ science with future CMB surveys like the CMB-S4 experiment. 

Abstract: Evidently, magnetic moments are successful probes for uncovering new physics. The precision measurement of the anomalous magnetic moment of the muon, aμ= (gμ−2)⁄2 , continues to play an important role in particle physics. Analyzing the data from 2019 and 2020 Fermilab accelerator operation years, the Fermilab Muon g-2 Experiment has measured the magnetic anomaly for the positive muon to unprecedent precision at 215 parts per billion. The experiment reports a total systematic uncertainty of 70 parts per billion. This value surpasses the proposal goal of 100 parts per billion. The measurement is consistent with the results produce from the 2018 data taking period. Combining with Fermilab previous measurement and Brookhaven National Laboratory experimental value, the new world’s average for muon g-2 is aμ= 116592059(22)(0.19 ppm). This talk presents an overview of the Fermilab Muon g-2 Experiment, the procedure for extracting the anomalous magnetic moment of the muon and a comparison between 2021and 2023 published results. Finally, the presentation will speak briefly on the Standard Model prediction, which has cause conflicts over the past two years.

Abstract: The DUNE physics program primarily focuses on signals in the GeV energy range. In recent years, DUNE's potential as a low-energy experiment has been explored expecting some sensitivity to signals as low as 5-10 MeV such as supernova burst and solar neutrinos. In this presentation I discuss the requirements and modifications that could extend DUNE's sensitivity to energies as low as 2MeV which would enhance DUNE's physics program and could expand it to enable searches for neutrino-less double-beta decay in xenon-doped liquid argon. I will present the modifications we propose with corresponding sensitivity estimates for measurements of the absolute neutrino mass scale (mββ) beyond the sensitivities expected from current and next generation neutrino-less double beta decay experiments. I will describe the rich R&D program that this research avenue would open for DUNE in the coming years.