arXiv subjects

Frank F. Deppisch

Publications and source records attributed to Frank F. Deppisch.

At least 37 records · Page 2Linked to original sources

arXiv2023

Heavy Neutrinos at the FCC-hh in the $U(1)_{B-L}$ Model

We investigate the potential of the 100 TeV future circular collider (FCC-hh) to probe heavy neutrinos. We concentrate in particular on heavy neutrino production via a $U(1)_{B-L}$ $Z'$ gauge boson and contrast the resulting limits with that mediated by Standard Model weak currents. We consider heavy neutrino decays to semi-leptonic as well as fully leptonic final states, particularly with muon flavour, and we show the importance of considering searches both in prompt and displaced decays of the heavy neutrinos. For prompt final states, semi-leptonic modes are more promising due to smaller background and larger yields, and TeV-scale heavy neutrinos with active-sterile mixing compatible with light neutrino mass generation in a seesaw scenario can be probed for a 5 TeV $Z'$ and gauge coupling as low as $g_{B-L} = 10^{-2}$. Displaced vertex searches can extend this range to heavy neutrino masses as low as 10 GeV.

hep-ph↗

arXiv2023

Probing the Mechanism of Neutrinoless Double-Beta Decay in Multiple Isotopes

A large experimental program is being mounted to search for neutrinoless double-beta decay over the next decade. Multiple experiments using different target isotopes are being prepared to explore the whole parameter space allowed for inverted-ordered light neutrinos, and have the potential to make discoveries in several other scenarios, including normal-ordered light neutrinos and other exotic mechanisms. We investigate to what extent long-range and exotic short-range contributions may be distinguished by combining measurements of the decay half-life across isotopes. We demonstrate how measurements in two isotopes may facilitate a joint measurement up to a two-fold degeneracy, and how a further measurement in a third isotope may remove this degeneracy. We also highlight the precision of the nuclear matrix elements needed to convert half-lives into information on the underlying decay mechanism. Considering their correlations and uncertainties in the framework of a global Bayesian analysis, we assess the consequences of a possible future 10-fold reduction in uncertainties. Our work motivates an experimental program measuring neutrinoless double-beta decay in more than one isotope, as this would break parameter degeneracies and advance our understanding of particle physics beyond the Standard Model.

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arXiv2022

Report of the Topical Group on Physics Beyond the Standard Model at Energy Frontier for Snowmass 2021

This is the Snowmass2021 Energy Frontier (EF) Beyond the Standard Model (BSM) report. It combines the EF topical group reports of EF08 (Model-specific explorations), EF09 (More general explorations), and EF10 (Dark Matter at Colliders). The report includes a general introduction to BSM motivations and the comparative prospects for proposed future experiments for a broad range of potential BSM models and signatures, including compositeness, SUSY, leptoquarks, more general new bosons and fermions, long-lived particles, dark matter, charged-lepton flavor violation, and anomaly detection.

hep-ph↗

arXiv2022

Probing Active-Sterile Neutrino Transition Magnetic Moments with Photon Emission from CE$ν$NS

In the presence of transition magnetic moments between active and sterile neutrinos, the search for a Primakoff upscattering process at coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments can provide stringent constraints on the neutrino magnetic moment. We show that a radiative upscattering process with an emitted photon in the final state can induce a novel coincidence signal at CE$ν$NS experiments that can also probe neutrino transition magnetic moments beyond existing limits. Furthermore, the differential distributions for such a radiative mode can also potentially be sensitive to the Dirac vs. Majorana nature of the sterile state mediating the process. This can provide valuable insights into the nature and mass generation mechanism of the light active neutrinos.

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arXiv2022

Probes of Heavy Sterile Neutrinos

We review probes of heavy sterile neutrinos, focusing on direct experimental searches and neutrinoless double beta decay. Working in a phenomenological parametrization, we emphasize the importance of the nature of sterile neutrinos in interpreting neutrinoless double beta decay searches. While current constraints on the active-sterile neutrino mixing are already stringent, we highlight planned future efforts that will probe regimes motivated by the lightness of active neutrinos.

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arXiv2022

Requirements on Quantum Superpositions of Macro-Objects for Sensing Neutrinos

We examine a macroscopic system in a quantum superposition of two spatially separated localized states as a detector for a stream of weakly interacting relativistic particles. We do this using the explicit example of neutrinos with MeV-scale energy scattering from a solid object via neutral-current neutrino-nucleus scattering. Presuming the (anti-)neutrino source to be a nuclear fission reactor, we utilize the estimated flux and coherent elastic neutrino-nucleus cross section to constrain the spatial separation $Δ$x and describe the temporal evolution of the sensing system. Particularly, we find that a potentially measurable relative phase between quantum superposed components is obtained for a single gram scale mass placed in a superposition of spatial components separated by $10^{-14}$m under sufficient cooling and background suppression.

quant-ph↗

arXiv2022

Neutrinoless Double Beta Decay via Light Neutralinos in R-Parity Violating Supersymmetry

We perform a study of neutrinoless double beta ($0νββ$) decay mediated by the lightest neutralino of arbitrary mass in the Minimal Supersymmetric Standard Model (MSSM) under the presence of R-parity violating trilinear interactions. In this scenario, the exchange of the lightest neutralino can result in $0νββ$ decay of either long-range or short-range behaviour, depending on the neutralino mass. Using nuclear matrix elements calculated in the Interacting Boson Model, we use an interpolation between the long- and short-range behaviours with an approximate formula. The non-observation of $0νββ$ decay is then used to place constraints on the supersymmetry parameter space, compatible with constraints from collider experiments. We compare these constraints to bounds from pion decays, CKM unitarity and Big Bang Nucleosynthesis.

hep-ph↗

arXiv2022

The Present and Future Status of Heavy Neutral Leptons

The existence of non-zero neutrino masses points to the likely existence of multiple SM neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as Heavy Neutral Leptons (HNLs). In this white paper we discuss the present experimental status of HNLs including colliders, beta decay, accelerators, as well as astrophysical and cosmological impacts. We discuss the importance of continuing to search for HNLs, and its potential impact on our understanding on key fundamental questions, and additionally we outline the future prospects for next-generation future experiments or upcoming accelerator run scenarios.

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arXiv2022

Displaced fat-jets and tracks to probe boosted right-handed neutrinos in the $U(1)_{B-L}$ model

We investigate the pair-production of Right-Handed Neutrinos (RHNs) via a $B-L$ $Z'$ boson and the detection prospects at the High-Luminosity run of the LHC (HL-LHC) and a future $pp$ collider (FCC-hh). We focus on RHN states with a mass of $10-70$ GeV which naturally results in displaced vertices for small active-sterile mixing strengths. Being produced through a mass resonance with $m_{Z'} \ge 1$ TeV, the RHNs are heavily boosted, leading to collimated decay products that give rise to fat-jets. We investigate the detection prospect of dedicated signatures in the inner detector and the muon spectrometer, namely a pair of displaced fat-jets and the associated tracks, respectively. We find that both the HL-LHC and FCC-hh can be sensitive to small active-sterile mixing $V_{μN} > 10^{-6}$ and $V_{μN} > 10^{-7}$ with the number of events reaching $\mathcal{O}(10)$ and $\mathcal{O}(10^3)$, respectively. This allows probing the generation of light neutrino masses through the Seesaw mechanism in this scenario.

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arXiv2022

The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

hep-ex↗

arXiv2021

Least-Informative Priors for $0νββ$ Decay Searches

Bayesian parameter inference techniques require a choice of prior distribution which can strongly impact the statistical conclusions drawn. We discuss the construction of least-informative priors for neutrinoless double beta decay searches. Such priors attempt to be objective by maximizing the information gain from an experimental setup. In a parametrization using the lightest neutrino mass $m_l$ and an effective Majorana phase parameter $Φ$, we construct such a prior using two different approaches and compare them with the standard flat and logarithmic priors in $m_l$.

hep-ph↗

arXiv2021

Two-Neutrino Double Beta Decay with Sterile Neutrinos

Usually considered a background for experimental searches for the hypothetical neutrinoless double beta decay process, two-neutrino double beta decay nevertheless provides a complementary probe of physics beyond the Standard Model. In this paper we investigate how the presence of a sterile neutrino, coupled to the Standard Model either via a left-handed or right-handed current, affects the energy distribution and angular correlation of the outgoing electrons in two-neutrino double beta decay. We pay particular attention on the behaviour of the energy distribution at the kinematic endpoint and we estimate the current limits on the active-sterile mixing and effective right-handed coupling using current experimental data as a function of the sterile neutrino mass. We also investigate the sensitivities of future experiments. Our results complement the corresponding constraints on sterile neutrinos from single beta decay measurements in the 0.1 - 10 MeV mass range.

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arXiv2021

Probing lepton number violating interactions in rare kaon decays

We investigate the possibility to probe lepton number violating (LNV) operators in the rare kaon decay $K\toπνν$. Performing the analysis in the Standard Model effective field theory with only light active Majorana neutrinos, we determine the current limits on the corresponding LNV physics scale from the past E949 experiment at BNL as well as the currently operating experiments NA62 at CERN and KOTO at J-PARC. We focus on the specific signature of scalar currents in $K\toπνν$ arising from the LNV nature of the operators and study the effect on the experimental sensitivity, stressing the need for dedicated searches for beyond the SM currents. We find that the rare kaon decays probe high operator scales $Λ_\text{LNV} \approx 15$ to $20$ TeV in different quark and neutrino flavours compared to neutrinoless double beta decay. Furthermore, we comment that the observation of LNV in kaon decays can put high-scale leptogenesis under tension. Finally, we discuss the connection with small radiatively generated neutrino masses and show how the severe constraints therefrom can be evaded in a minimal ultraviolet-complete scenario featuring leptoquarks.

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arXiv2020

Implications of Rare Kaon Decays on Lepton Number Violating Interactions

We explore the possibility of lepton number violation (LNV) manifesting in the rare kaon decay $K\toπνν$, and its consequences for radiative neutrino mass generation and the washout of Lepton asymmetry in high-scale leptogenesis scenarios. We perform the analysis in a model-independent framework, the Standard Model effective field theory (SMEFT), and discuss the possible LNV nature of the rare kaon decay in the context of the currently operating NA62 experiment at CERN. We find that, in case of a LNV interaction, its detection would put high-scale leptogenesis under tension and would hint to small radiatively generated neutrino masses.

hep-ph↗

arXiv2020

Analysis of Light Neutrino Exchange and Short-Range Mechanisms in $0νββ$ Decay

Neutrinoless double beta decay ($0νββ$) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focussing on so called short-range operators of $0νββ$ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wavefunctions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical results are presented together with up-to-date limits on the standard mass mechanism and effective $0νββ$ short-range operators in the IBM-2 framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, Left-Right symmetry and R-parity violating supersymmetry.

hep-ph↗

arXiv2020

Searching for New Physics in Two-Neutrino Double Beta Decay

Motivated by non-zero neutrino masses and the possibility of New Physics discovery, a number of experiments search for neutrinoless double beta decay. While hunting for this hypothetical nuclear process, a significant amount of two-neutrino double beta decay data has become available. Although these events are regarded and studied mostly as the background of neutrinoless double beta decay, they can be also used to probe physics beyond the Standard Model. In this paper we show how the presence of right-handed leptonic currents would affect the energy distribution and angular correlation of the outgoing electrons in two-neutrino double beta decay. Consequently, we estimate constraints imposed by currently available data on the existence of right-handed neutrino interactions without having to assume their nature. In this way our results complement the bounds coming from the non-observation of neutrinoless double beta decay as they limit also the exotic interactions of Dirac neutrinos. We perform a detailed calculation of two-neutrino double beta decay under the presence of exotic (axial-)vector currents and we demonstrate that current experimental searches can be competitive to existing limits.

hep-ph↗

arXiv2020

Probing New Physics with Long-Range Neutrino Interactions: An Effective Field Theory Approach

We investigate forces induced by the exchange of two light neutrinos between Standard Model (SM) fermions in the presence of effective operators parametrising physics beyond the SM. We first set up a general framework in which we derive the long-range potential mediated by weakly interacting neutrinos in the SM, retaining both spin-independent and spin-dependent terms. We then derive neutrino-mediated potentials when there are vector, scalar and tensor non-standard interactions present as well as an exotic neutrino magnetic moment. Examining the phenomenology of such long-range potentials in atomic scale laboratory experiments, we derive upper bounds on the Wilson coefficients of the effective operators and compare these to those from processes such as charged lepton flavour violation.

hep-ph↗

arXiv2020

Neutrino Self-Interactions and Double Beta Decay

Neutrino Self-Interactions ($ν$SI) beyond the Standard Model are an attractive possibility to soften cosmological constraints on neutrino properties and also to explain the tension in late and early time measurements of the Hubble expansion rate. The required strength of $ν$SI to explain the $4σ$ Hubble tension is in terms of a point-like effective four-fermion coupling that can be as high as $10^9\, G_F$, where $G_F$ is the Fermi constant. In this work, we show that such strong $ν$SI can cause significant effects in two-neutrino double beta decay, leading to an observable enhancement of decay rates and to spectrum distortions. We analyze self-interactions via an effective operator as well as when mediated by a light scalar. Data from observed two-neutrino double beta decay is used to constrain $ν$SI, which rules out the regime around $10^9\, G_F$.

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