Direct Detection Data Research Articles

Automating data classification for label-free point-of-care biosensing in real complex samples

Surface-based affinity biosensors present a promising avenue for point-of-care (POC) pathogen detection in real-world samples. While laboratory-based devices commonly employ various techniques to mitigate noise, signal drifts, fluidic artifacts, and other system imperfections, their simple cost-effective POC counterparts designed for field use frequently lack such capabilities. This paper addresses this gap by introducing a procedure for automatically classifying pathogen presence in unprocessed liquids from direct detection data measured by a simple POC quartz crystal microbalance sensor device. The procedure integrates classical analytical tools such as filtering, data selection, baseline de-drifting, and result calculation in tailored successive steps, considering the nature of the sensor signal and the challenges posed by real-world media. We show that the developed procedure exhibits exceptional robustness across different biosensing assays and complex real-world media. Through optimizing parameters using diverse datasets encompassing Escherichia coli O157:H7 (E. coli) and SARS-CoV-2 detection in various media including food-derived matrices and cell culture media, we achieved rates of successful detection as high as 80.8 % and 90.9 % for E. coli and SARS-CoV-2, respectively, without extensive machine learning. Furthermore, we analyse the sensitivity of the procedure to variations of input parameters and with examples discuss key factors influencing overall procedure accuracy. Our results suggest that this exceptionally robust method holds potential as a straightforward tool for automating sample classification in point-of-care diagnostics, underpinning its promising broader applicability.

Scaling comb-driven resonator-based DWDM silicon photonic links to multi-Tb/s in the multi-FSR regime

The use of chip-based micro-resonator Kerr frequency combs in conjunction with dense wavelength-division multiplexing (DWDM) enables massively parallel intensity-modulated direct-detection data transmission with low energy consumption. Resonator-based modulators and filters used in such systems can limit the number of usable wavelength channels due to practical constraints on the maximum achievable free spectral range (FSR). In this work, we introduce the design of multi-Tb/s comb-driven resonator-based silicon photonic links by leveraging the multi-FSR regime. We demonstrate the viability of the link architecture with yield estimates that are supported by extensive wafer-scale measurements of 704 micro-resonators fabricated in a commercial complementary metal–oxide–semiconductor foundry. We show that a 2.80 Tb/s link is realizable with a ≥6σ yield (∼99.999%), and that aggregate bandwidths of 3.76 Tb/s and 4.72 Tb/s are possible if yield targets are relaxed (3σ and 1σ, respectively). All designs represent a 1.94−3.28× boost to aggregate link bandwidth while maintaining BER≤10−10 performance, with a theoretical bandwidth of 10.51 Tb/s being possible for sufficiently robust resonators. We use high-speed BER measurements to inform co-optimization of data rate and aggressor spacing (λag), limiting any additional loss-based power penalties to off-resonance insertion loss (IL) and routing loss. This work demonstrates that, through the multi-FSR regime, there is a clear path toward Kerr comb-driven ultra-broadband, high bandwidth silicon photonic links that can support next-generation data centers and high-performance computers.

Halo-independent dark matter electron scattering analysis with in-medium effects

Dark matter (DM)-electron scattering is a prime target of a number of direct DM detection experiments and constitutes a promising avenue for exploring interactions of DM in the sub-GeV mass-range, challenging to probe with nuclear recoils. We extend the recently proposed halo-independent analysis method for DM-electron scattering, which allows to infer the local DM halo properties without any additional assumptions about them, to include in-medium effects through dielectric functions of the target material. We show that in-medium effects could significantly affect halo-independent analysis response functions for germanium and silicon and thus are essential for proper inference of local DM halo characteristics from direct DM detection data.

Treatment of systematic uncertainties with Bayesian networks

We show an innovative approach based on Bayesian networks and linear algebra providing a solid and complete solution to the problem of the detector response and the related systematic effects. As a case study, we consider the dark matter direct detection searches. In this context, it is crucial to develop a reliable analysis framework, which is able to take into account all the relevant systematic effects in a clean and accessible way. The relations connecting the calibration parameters of the experiment to the final observed data spectrum are characterized by substantial complexity and non linearity. Usual approaches to direct detection data analysis involve multi-templates techniques. By means of our technique however it is possible to represent the full detector response to any background/signal event keeping the dependence on the detector parameters explicit. The advantage of this kind of approach is twofold: from the statistical point of view it is a solid and rigorous way to perform the analysis; from the computational point of view, we demonstrate that it is possible to represent the response of the detector by a set of matrices, allowing to use a GPU accelerated analysis code to improve the performance of the fit.

Microresonator frequency comb based high-speed transmission of intensity modulated direct detection data

Abstract Globally, the long-haul transmission of ultra-high bandwidth data is enabled through coherent communications. Driven by the rapid pace of growth in interconnectivity over the last decade, long-haul data transmission has reached capacities on the order of tens to hundreds of terabits per second, over fiber reaches which may span thousands of kilometers. Data center communications operate in regimes featuring shorter reaches and higher cost sensitivity. While integrated microresonator frequency combs are poised to revolutionize light sources used for high-speed data transmission over fiber, recent progress has focused largely on coherent detection schemes. Furthermore, though state-of-the-art intensity modulators are advancing in speed, it has not been demonstrated in the literature if microresonator-based comb lines can accommodate higher intensity modulated direction data (IMDD) line rates in tandem with these advancements. In this manuscript, we demonstrate the use of microresonator frequency combs pumped with a single laser for the transmission of high-speed IMDD data. We demonstrate error-free transmission of 30 Gbs−1 per comb non-return-to-zero data over fiber lengths of 6 km, as well as bit error rates under the forward error correction limit for propagation through 20 km of optical fiber. 60 Gbs−1 and 42 Gbs−1 pulse modulation amplitude 4 (PAM4) data modulated on each frequency comb line is further quantified to have a bit error rate under the forward error correction limit for fiber reaches of up to 6 km and 20 km respectively. The results showcase CMOS-compatible microresonator frequency comb modulated using IMDD formats as a promising technology for high-speed transmission in the data center transceiver industry.

A semi-supervised approach to dark matter searches in direct detection data with machine learning

The dark matter sector remains completely unknown. It is therefore crucial to keep an open mind regarding its nature and possible interactions. Focusing on the case of Weakly Interacting Massive Particles, in this work we make this general philosophy more concrete by applying modern machine learning techniques to dark matter direct detection. We do this by encoding and decoding the graphical representation of background events in the XENONnT experiment with a convolutional variational autoencoder. We describe a methodology that utilizes the `anomaly score' derived from the reconstruction loss of the convolutional variational autoencoder as well as a pre-trained standard convolutional neural network, in a semi-supervised fashion. Indeed, we observe that optimum results are obtained only when both unsupervised and supervised anomaly scores are considered together. A data set that has a higher proportion of anomaly score is deemed anomalous and deserves further investigation. Contrary to classical analyses, in principle all information about the events is used, preventing unnecessary information loss. Lastly, we demonstrate the reach of learning-focused anomaly detection in this context by comparing results with classical inference, observing that, if tuned properly, these techniques have the potential to outperform likelihood-based methods.

Leptoquark manoeuvres in the dark: a simultaneous solution of the dark matter problem and the {R}_{D^{left(ast right)}} anomalies

The measured branching fractions of B-mesons into leptonic final states derived by the LHCb, Belle and BaBar collaborations hint towards the breakdown of lepton flavour universality. In this work we take at face value the so-called {R}_{D^{left(ast right)}} observables that are defined as the ratios of neutral B-meson charged-current decays into a D(*)-meson, a charged lepton and a neutrino final state in the tau and light lepton channels. A well-studied and simple solution to this charged current anomaly is to introduce a scalar leptoquark S1 that couples to the second and third generation of fermions. We investigate how S1 can also serve as a mediator between the Standard Model and a dark sector. We study this scenario in detail and estimate the constraints arising from collider searches for leptoquarks, collider searches for missing energy signals, direct detection experiments and the dark matter relic abundance. We stress that the production of a pair of leptoquarks that decays into different final states (i.e. the commonly called “mixed” channels) provides critical information for identifying the underlying dynamics, and we exemplify this by studying the tτbν and the resonant S1 plus missing energy channels. We find that direct detection data provides non-negligible constraints on the leptoquark coupling to the dark sector, which in turn affects the relic abundance. We also show that the correct relic abundance can not only arise via standard freeze-out, but also through conversion-driven freeze-out. We illustrate the rich phenomenology of the model with a few selected benchmark points, providing a broad stroke of the interesting connection between lepton flavour universality violation and dark matter.

Halo-independent analysis of direct dark matter detection through electron scattering

Sub-GeV mass dark matter particles whose collisions with nuclei would not deposit sufficient energy to be detected, could instead be revealed through their interaction with electrons.Analyses of data from direct detection experiments usually require assuming a local dark matter halo velocity distribution. In the halo-independent analysis method, properties of this distribution are instead inferred from direct dark matter detection data, which allows then to compare different data without making any assumption on the uncertain local dark halo characteristics. This method has so far been developed for and applied to dark matter scattering off nuclei. Here we demonstrate how this analysis can be applied to scattering off electrons.

Recommended conventions for reporting results from direct dark matter searches

The field of dark matter detection is a highly visible and highly competitive one. In this paper, we propose recommendations for presenting dark matter direct detection results particularly suited for weak-scale dark matter searches, although we believe the spirit of the recommendations can apply more broadly to searches for other dark matter candidates, such as very light dark matter or axions. To translate experimental data into a final published result, direct detection collaborations must make a series of choices in their analysis, ranging from how to model astrophysical parameters to how to make statistical inferences based on observed data. While many collaborations follow a standard set of recommendations in some areas, for example the expected flux of dark matter particles (to a large degree based on a paper from Lewin and Smith in 1995), in other areas, particularly in statistical inference, they have taken different approaches, often from result to result by the same collaboration. We set out a number of recommendations on how to apply the now commonly used Profile Likelihood Ratio method to direct detection data. In addition, updated recommendations for the Standard Halo Model astrophysical parameters and relevant neutrino fluxes are provided. The authors of this note include members of the DAMIC, DarkSide, DARWIN, DEAP, LZ, NEWS-G, PandaX, PICO, SBC, SENSEI, SuperCDMS, and XENON collaborations, and these collaborations provided input to the recommendations laid out here. Wide-spread adoption of these recommendations will make it easier to compare and combine future dark matter results.

A dark clue to seesaw and leptogenesis in a pseudo-Dirac singlet doublet scenario with (non)standard cosmology

We propose an appealing alternative scenario of leptogenesis assisted by dark sector which leads to the baryon asymmetry of the Universe satisfying all theoretical and experimental constraints. The dark sector carries a non minimal set up of singlet doublet fermionic dark matter extended with copies of a real singlet scalar field. A small Majorana mass term for the singlet dark fermion, in addition to the typical Dirac term, provides the more favourable dark matter of pseudo-Dirac type, capable of escaping the direct search. Such a construction also offers a formidable scope to radiative generation of active neutrino masses. In the presence of a (non)standard thermal history of the Universe, we perform the detailed dark matter phenomenology adopting the suitable benchmark scenarios, consistent with direct detection and neutrino oscillations data. Besides, we have demonstrated that the singlet scalars can go through CP-violating out of equilibrium decay, producing an ample amount of lepton asymmetry. Such an asymmetry then gets converted into the observed baryon asymmetry of the Universe through the non-perturbative sphaleron processes owing to the presence of the alternative cosmological background considered here. Unconventional thermal history of the Universe can thus aspire to lend a critical role both in the context of dark matter as well as in realizing baryogenesis.

Laser Phase Noise in Ring Resonator Assisted Direct Detection Data Transmission

We introduce an analytical model describing the statistical and spectral properties of laser phase noise induced intensity noise in ring-resonator-based modulation. The model is validated with single sideband orthogonal frequency division multiplexing (SSB-OFDM) implemented with a silicon photonics resonantly-assisted Mach-Zehnder modulator (RA-MZM). Excellent agreement of experimental data with full link simulations, in which phase noise conversion is treated with the analytical model, confirms its validity. Moreover, we demonstrate 30 Gb/s raw data rate transmission with SSB-OFDM over 20 km of single-mode fiber with a bit error ratio below the 20% forward error correction (FEC) limit for three independently run channels of the RA-MZM, each supplied with off-the-shelf 1 MHz linewidth distributed feedback lasers.

Constraining electroweakinos in the minimal Dirac gaugino model

Supersymmetric models with Dirac instead of Majorana gaugino masses have distinct phenomenological consequences. In this paper, we investigate the electroweakino sector of the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) with regards to dark matter (DM) and collider constraints. We delineate the parameter space where the lightest neutralino of the MDGSSM is a viable DM candidate, that makes for at least part of the observed relic abundance while evading constraints from DM direct detection, LEP and low-energy data, and LHC Higgs measurements. The collider phenomenology of the thus emerging scenarios is characterised by the richer electroweakino spectrum as compared to the Minimal Supersymmetric Standard Model (MSSM) -6 neutralinos and 3 charginos instead of 4 and 2 in the MSSM, naturally small mass splittings, and the frequent presence of long-lived particles, both charginos and/or neutralinos. Reinterpreting ATLAS and CMS analyses with the help of SmodelS and MadAnalysis 5, we discuss the sensitivity of existing LHC searches for new physics to these scenarios and show which cases can be constrained and which escape detection. Finally, we propose a set of benchmark points which can be useful for further studies, designing dedicated experimental analyses and/or investigating the potential of future experiments.

Observationally inferred dark matter phase-space distribution and direct detection experiments

We present a detailed analysis of the effect of an observationally determined dark matter (DM) velocity distribution function (VDF) of the Milky Way (MW) on DM direct detection rates. We go beyond local kinematic tracers and use rotation curve data up to 200 kpc to construct a MW mass model and self-consistently determine the local phase-space distribution of DM. This approach mitigates any incomplete understanding of local dark matter-visible matter degeneracies that can affect the determination of the VDF. Comparing with the oft used Standard Halo Model (SHM), which assumes an isothermal VDF, we look at how the tail of the empirically determined VDF alters our interpretation of the present direct detection WIMP DM cross section exclusion limits. While previous studies have suggested a very large difference (of more than an order of magnitude) in the bounds at low DM masses, we show that accounting for the detector response at low threshold energies, the difference is still significant although less extreme. The change in the number of signal events, when using the empirically determined DM VDF in contrast to the SHM VDF, is most prominent for low DM masses for which the shape of the recoil energy spectrum depends sensitively on the detector threshold energy as well as detector response near the threshold. We demonstrate that these trends carry over to the respective DM exclusion limits, modulo detailed understanding of the experimental backgrounds. With the unprecedented precision of astrometric data in the GAIA era, use of observationally determined DM phase-space will become a critical and necessary ingredient for DM searches. We provide an accurate fit to the current best observationally determined DM VDF (and self-consistent local DM density) for use in analyzing current DM direct detection data by the experimental community.

Direct detection experiments at the neutrino dipole portal frontier

Heavy sterile neutrinos are typically invoked to accommodate the observed neutrino masses, by positing a new Yukawa term connecting these new states to the neutrinos in the electroweak doublet. However, given our ignorance of the neutrino sector we should explore additional interactions such sterile neutrinos may have with the SM. In this paper, we study the dimension-5 operator which couples the heavy state to a light neutrino and the photon. We find that the recent XENON1T direct detection data can improve the limits on this "Neutrino Dipole Portal" by up to an order of magnitude over previous bounds. Future direct detection experiments may be able to extend these bounds down to the level probed by SN1987A.

TeV SUSY dark matter confronted with the current direct and indirect detection data

In the minimal supersymmetric standard model (MSSM) the lightest superparticle (LSP) can be a TeV neutralino (mainly dominated by higgsino or wino) which serves as a dark matter candidate with correct thermal relic density. In this work we confront the 1–3 TeV neutralino dark matter with the latest direct and indirect detections from PandaX and AMS-02/DAMPE. Considering various scenarios with decoupled sfermions, with A-mediated annihilation, with squark or stop coannihilation, we find that the parameter space is stringently constrained by the direct detection limits. In the allowed parameter space, the TeV neutralino dark matter annihilation contribution to the anti-proton flux is found to agree with the AMS-02 data while its contribution to eletron/positron flux is too small to cause any visible excess.

Interplay of the LHC and non-LHC dark matter searches in the effective field theory approach

We present accurate and up-to-date constraints on the complete set of dimension five and six operators with scalar, fermion and vector Dark Matter (DM). We find limits using LHC mono-jet data, spin inde- pendent and spin dependent direct searches, relic density and CMB, and show the interplay between high and low energy data in setting bounds on the parameter space. In order to properly compare data taken at different energies, we take into account the effect of the running and mixing of operators. We also take into account the local density uncertainties affecting direct detection data, and apply EFT validity criteria related to the cut on the invariant mass of DM pair production at the LHC, which turns out to be especially important for the case of vector DM. Finally, we estimate the potential of the future LHC runs to probe DM parameter space.

Consistency test of the AMS-02 antiproton excess with direct detection data based on the effective field theory approach

The potential antiproton excess in the AMS-02 data is of much interest and can probably come from dark matter annihilations. Based on the effective field theory approach, in this work we investigate the compatibility of the DM interpretation of the AMS-02 antiproton excess and the null results from direct detection experiments, LUX, PandaX-II, and XENON1T. We focus on dimension-five and -six operators with fermion DM . Only one of dimension-five and one of dimension-six operators can successfully account for the antiproton excess, while the rest either are excluded by direct detection or require very small cut-off scales which invalidate the effective field theory approach.

Exploring non minimal Universal Extra Dimensional model at the LHC

We study the collider phenomenology of non minimal universal extra dimensional (nmUED) model in the context of the Large Hadron Collider at CERN. nmUED is an incarnation of the Standard Model in 4 + 1 space-time dimensions compactified on an S1/Z2 orbifold supplemented with boundary localized operators with unknown coefficients. These coefficients parametrize the radiative corrections which are somehow arbitrary due to the lack of knowledge of the cut-off scale of such effective theory. It is possible to tune the masses and couplings of the Kaluza Klein (KK) excitations by tuning these parameters. Two scenarios with different mass hierarchies among the KK-excitations have been considered. A detailed study of production cross-sections and different decay modes of KK-particles are also presented. We calculate the correlated bounds on masses of KK-particles using the LHC data (in case of production of strongly interacting particles) and data (in case of electroweak productions). We work in a KK-parity conserving scenario where the lightest KK-particle is a potential dark (DM) matter candidate. We use the additional constraints coming from the observed DM relic density of the universe to identify the allowed parameter space. The current status of a nmUED model in the light of DM direct detection data is also examined. The present investigation reveals that production and subsequent leptonic decays of KK-electroweak gauge bosons as massive as 1 TeV, lead to observable trilepton signature with a luminosity of 1 ab−1 which will be realized in near future.

Muon g−2 and dark matter suggest nonuniversal gaugino masses: SU(5)×A4 case study at the LHC

We argue that in order to account for the muon anomalous magnetic moment $g\ensuremath{-}2$, dark matter and LHC data, nonuniversal gaugino masses ${M}_{i}$ at the high scale are required in the framework of the minimal supersymmetric standard model. We also need a right-handed smuon ${\stackrel{\texttildelow{}}{\ensuremath{\mu}}}_{R}$ with a mass around 100 GeV, evading LHC searches due to the proximity of a neutralino ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{0}$ several GeV lighter which allows successful dark matter. We discuss such a scenario in the framework of an $SU(5)$ grand unified theory (GUT) combined with ${A}_{4}$ family symmetry, where the three $\overline{5}$ representations form a single triplet of ${A}_{4}$ with a unified soft mass ${m}_{F}$, while the three 10 representations are singlets of ${A}_{4}$ with independent soft masses ${m}_{T1},{m}_{T2},{m}_{T3}$. Although ${m}_{T2}$ (and hence ${\stackrel{\texttildelow{}}{\ensuremath{\mu}}}_{R}$) may be light, the muon $g\ensuremath{-}2$ and relic density also requires light ${M}_{1}\ensuremath{\simeq}250\text{ }\text{ }\mathrm{GeV}$, which is incompatible with universal gaugino masses due to LHC constraints on ${M}_{2}$ and ${M}_{3}$ arising from gaugino searches. After showing that universal gaugino masses ${M}_{1/2}$ at the GUT scale are excluded by gluino searches, we provide a series of benchmarks which show that while ${M}_{1}={M}_{2}\ensuremath{\ll}{M}_{3}$ is in tension with 8 and 13 TeV LHC data, ${M}_{1}<{M}_{2}\ensuremath{\ll}{M}_{3}$ is currently allowed. Even this scenario is almost excluded by the tension between the muon $g\ensuremath{-}2$, relic density, dark matter direct detection and LHC data. We focus on a region of parameter space that has not been studied in detail before being characterized by low Higgsino mass $\ensuremath{\mu}\ensuremath{\approx}\ensuremath{-}300\text{ }\text{ }\mathrm{GeV}$, as required by the muon $g\ensuremath{-}2$. The LHC will be able to fully test this scenario with the upgraded luminosity via muon-dominated tri- and dilepton signatures resulting from Higgsino-dominated ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{\ifmmode\pm\else\textpm\fi{}}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{2}^{0}$ and ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{+}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{\ensuremath{-}}$ production.

Identifying WIMP dark matter from particle and astroparticle data

One of the most promising strategies to identify the nature of dark matter consists in the search for new particles at accelerators and with so-called direct detection experiments. Working within the framework of simplified models, and making use of machine learning tools to speed up statistical inference, we address the question of what we can learn about dark matter from a detection at the LHC and a forthcoming direct detection experiment. We show that with a combination of accelerator and direct detection data, it is possible to identify newly discovered particles as dark matter, by reconstructing their relic density assuming they are weakly interacting massive particles (WIMPs) thermally produced in the early Universe, and demonstrating that it is consistent with the measured dark matter abundance. An inconsistency between these two quantities would instead point either towards additional physics in the dark sector, or towards a non-standard cosmology, with a thermal history substantially different from that of the standard cosmological model.