@inproceedings{22820,
  abstract     = {We introduce a new primitive, called beholder signatures (Full version [14] of the paper is available at https://eprint.iacr.org/2025/1900), which, in some sense, are the opposite of blind signatures. In a beholder signature, one signs a commitment to a (potentially very long) message, and the signature attests that the parties participating in the signing process, who know the secret key, jointly also know the entire committed message. This guarantee holds even against distributed adversaries that use secure multi-party computation (MPC) to produce the signature. We work in the distributed adversarial model (Dziembowski, Faust, and Lizurej, Crypto’23), where one assumes that it is infeasible to evaluate a large number of hash queries without any of the participating parties learning the input. We propose a construction of beholder signatures in the random oracle model. The starting point of our construction is proofs of complete knowledge, recently proposed by (Kelkar et al. CCS’24), which build on Fischlin’s transformation of a sigma protocol to a non-interactive, straight-line extractable zero-knowledge proof of knowledge. Our scheme is concretely efficient and comes with a proof-of-concept implementation using Schnorr as the underlying sigma protocol.

The primary applications of beholder signatures can be found within the blockchain space. In particular, we describe how to use them to construct proofs of custody (Feist, 2021) that do not require ephemeral keys and are non-interactive. We also outline applications to data dissemination, data availability, and proofs of replication.},
  author       = {Dziembowski, Stefan and Faust, Sebastian and Kedzior, Paweł and Mielniczuk, Marcin and Mohanty, Susil Kumar and Pietrzak, Krzysztof Z},
  booktitle    = {46th Annual International Cryptology Conference},
  isbn         = {9783032353733},
  issn         = {1611-3349},
  location     = {Santa Barbara, CA, United States},
  pages        = {134--165},
  publisher    = {Springer},
  title        = {{Beholder signatures}},
  doi          = {10.1007/978-3-032-35374-0_5},
  volume       = {16801},
  year         = {2026},
}

@phdthesis{21863,
  abstract     = {Atoms and photons, two things so different but yet so alike. The former, the building block of matter, something we learn about in school and imagine it as some tiny marbles encircled by other tinier marbles. The latter, an electromagnetic wave, a light particle or an excitation of the electromagnetic field. Quantum mechanics tells us about the properties of these two entities. And even if it sounds, looks and writes counter-intuitive, it has proven right for over a century now.

In this work, I elaborate on how we tested the laws of quantum mechanics and how we used them learn more about the tiny building blocks of nature and the fields they use to talk to each other. The atoms we use, are artificial. Superconducting qubits, small electrical circuits with quantized energy levels behave like electrons that transition between different orbitals in an atom. One of the qubits' advantages, is also a big disadvantage. We design the circuits' energy levels and fabricate them in a cleanroom. This allows for arbitrary spaced energy levels but in contrast to real atoms, prevents two superconducting qubits from being alike. Still, this qubit platform is one of the frontrunners for future quantum computing technology and testing fundamental physics due to their scalability.

We interface superconducting qubits, which operate in the GHz regime, with microwave photons. We use 3D aluminum cavities as mediators between qubits and photons. The cavities allow for non-destructive readout of the qubit state, they shield the qubits from noise at the qubit frequency and they give us an easy way to frequency-tune these joint systems.

We need to operate superconducting qubits and their cavities at millikelvin temperatures in dilution refrigerators. At higher temperatures, superconductivity suffers and even worse, the environment is filled with thermal noise photons. This poses a fundamental limitation on the scalability of superconducting qubit devices. Also connecting multiple devices in different fridges does not work over room temperature links because the microwave photons used for this purpose will be covered in noise and the quantum information they carry, will be unusable.

Infrared photons do not suffer from this noise problem since there are close to zero thermal noise photons at their frequencies at room temperature. We cannot simply interface superconducting devices with optical photons due their frequency mismatch and the destructive effect of optical photons on superconductors. Therefore, we use microwave-to-optics transducers that allow to convert microwave photons into optical ones and vice-versa. The transducers that we use are macroscopic electro-optic transducers using the Pockels effect in a disk-shaped Lithium Niobate whispering gallery mode resonator. By using a strong optical pump, photons from the two frequency domains experience a beam-splitter interaction and get converted from one to the other.

We measure the generated optical photons using elaborate optical setups, optical heterodyning and single photon detectors to gain knowledge about the qubit state or the converted microwave photons. Bridging the microwave and the optical world allows us to take advantage of both of their strengths but it also requires deep knowledge about both of their working principles.

In this work, we describe two experiments that our group conducted to showcase the opportunities that arise from interfacing superconducting qubits with optical photons but also the pitfalls, one may encounter on the way.

In the first experiment, we managed to all-optically read out a superconducting qubit. We show that the assignment fidelity, the probability that a measurement of the qubit state matches the prepared state, is close to equal for all-optical, microwave-to-optics and conventional microwave readout. We show T1 and T2 measurements for all three readout types and give an analysis of the noise caused by the optics. Finally, we show that the infrared light does not affect the qubit performance in a negative way but that the heating it causes does. This is an important insight that we used in the next experiment.

The second experiment is the upconversion of itinerant single microwave photons to the optical domain. We show that we can generate single microwave photons from a qubit-cavity system. We upconvert these single photons, measure them with a single photon detector and reconstruct their shape. By conducting a single photon Rabi measurement, we show correlations between the microwave and the optical domain. And by thorough signal-to-noise measurements and noise analysis, we find that we can generate single infrared photons with high signal-to-noise ratio 5.1 and low transducer added noise (<0.012 quanta). We show that this measurement creates a path towards entanglement of a superconducting qubit and an optical photon and what parameters need to be improved to achieve it. Additionally, this experiment is a proof of principle for an on-demand infrared single photon source. More generally, it allows to link microwave quantum technology in general to the optical domain.},
  author       = {Werner, Thomas},
  issn         = {2663-337X},
  keywords     = {Superconducting qubits, Quantum optics, Single photons and quantum effects, Nonlinear optics},
  pages        = {97},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Interfacing superconducting qubits with optical photons}},
  doi          = {10.15479/AT-ISTA-21863},
  year         = {2026},
}

@unpublished{21870,
  abstract     = {Superconducting qubits are a leading candidate for utility-scale quantum computing due to their fast gate speeds and steadily decreasing error rates. The requirement for millikelvin operating temperatures, however, creates a significant scaling bottleneck. Modular architectures using optical fiber links could bridge separate cryogenic nodes, but superconducting circuits do not have coherent optical transitions and microwave-to-optical conversion has not been shown for any non-classical photon state. In this work, we demonstrate the on-demand generation and tomographic reconstruction of itinerant single microwave photons at 8.9 GHz from a superconducting qubit. We upconvert this non-Gaussian state with a transducer added noise below 0.012 quanta and count the converted telecom photons at 193.4 THz with a signal-to-noise ratio of up to 5.1$\pm$1.1. We characterize the trade-offs between throughput and noise, and establish a viable path toward heralded entanglement distribution and gate teleportation. Looking ahead, these results empower existing superconducting devices to take a key role in distributed quantum technologies and heterogeneous quantum systems.},
  author       = {Werner, Thomas and Riyazi, Erfan and Hawaldar, Samarth and Sahu, Rishabh and Arnold, Georg M and Paul Falthansl-Scheinecker, Paul Falthansl-Scheinecker and Naranjo, Jennifer A. Sánchez and Loi, Dante and Kapoor, Lucky N. and Zemlicka, Martin and Qiu, Liu and Militaru, Andrei and Fink, Johannes M},
  booktitle    = {arXiv},
  title        = {{Electro-optic conversion of itinerant Fock states}},
  doi          = {10.48550/arXiv.2602.00928},
  year         = {2026},
}

@phdthesis{22745,
  author       = {Michalik, David},
  issn         = {2663-337X},
  pages        = {182},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Mechanistic insights into MDA5 selectivity and regulation}},
  doi          = {10.15479/AT-ISTA-22745},
  year         = {2026},
}

@article{22911,
  abstract     = {The shape of animal cells is controlled by their surface, which comprises the cell cortex, a peripheral actin network, tethered to the plasma membrane by membrane-to-cortex attachment proteins. Changes in cortical components have long been considered to dominate the regulation of forces and mechanical properties at the cell surface and drive morphogenesis. Here, we show that the coupling of the cortex to the membrane is also key for the regulation of its mechanical properties. By combining molecular engineering with biophysical approaches and in-cell cryo-electron tomography we describe the cell surface with nanometer-resolution and link its organization to cell-scale mechanics. We find that membrane-to-cortex attachment proteins can physically draw the cortex closer to the membrane, in a density and length-dependent manner. This reduction of the membrane-to-cortex distance controls the activity of the formin mDia1, leading to a reduction in cortical tension. Our study thus defines a novel mechanism whereby the membrane-to-cortex distance is a functional geometrical parameter that regulates cell surface properties.},
  author       = {Strauss, Léanne and Lembo, Sergio and Gérard, Samuel F. and Siggel, Marc and Cheng, Dorothy and Bergert, Martin and Foster, Sarah K. and Vermeil, Joseph and Toro-Nahuelpan, Mauricio and Fischer, Lena M. and Yu, Qin and Sitarska, Ewa and Chan, Chii Jou and Kosinski, Jan and Piel, Matthieu and Du Roure, Olivia and Heuvingh, Julien and Mahamid, Julia and Diz-Muñoz, Alba},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{The membrane-to-cortex distance regulates mDia1 activity to control cortical mechanics}},
  doi          = {10.1038/s41467-026-72845-3},
  volume       = {17},
  year         = {2026},
}

@article{22912,
  abstract     = {Deep convection from tropical cyclones (TCs) can reach the height of the tropopause and as such an interaction between the upper troposphere and lower stratosphere is likely to occur. Such interactions have been reported in both numerical and observational studies, mainly showing that subsidence from the stratosphere into the eye of an intensifying storm leads to a high-level warm core. However, the effect of this upper-level warming on the intensity of the TCs is not yet well understood. In this study, we show that subsiding air from the stratosphere beyond subsidence in the eye is the reason for the upper-level warming in idealized simulations. We further show that it is possible to quantify the effects of the upper-level warming on the potential intensity of the TC. Finally, we conclude that overshooting convection into the stratosphere causes the observed subsidence, as both become more pronounced with increasing sea-surface temperatures (SST).},
  author       = {Charinti, Giousef Alexandros and Davin, Andrea and Polesello, Andrea and Muller, Caroline J and Pasquero, Claudia},
  issn         = {1944-8007},
  journal      = {Geophysical Research Letters},
  number       = {17},
  publisher    = {Wiley},
  title        = {{Impact of upper-level warming on tropical cyclone intensity}},
  doi          = {10.1029/2025GL121307},
  volume       = {53},
  year         = {2026},
}

@inproceedings{21717,
  abstract     = {Robust Markov Decision Processes (RMDPs) generalize classical MDPs that consider uncertainties in transition probabilities by defining a set of possible transition functions. An objective is a set of runs (or infinite trajectories) of the RMDP, and the value for an objective is the maximal probability that the agent can guarantee against the adversarial environment. We consider (a) reachability objectives, where given a target set of states, the goal is to eventually arrive at one of them; and (b) parity objectives, which are a canonical representation for ω-regular objectives. The qualitative analysis problem asks whether the objective can be ensured with probability 1. In this work, we study the qualitative problem for reachability and parity objectives on RMDPs without making any assumption over the structures of the RMDPs, e.g., unichain or aperiodic. Our contributions are twofold. We first present efficient algorithms with oracle access to uncertainty sets that solve qualitative problems of reachability and parity objectives. We then report experimental results demonstrating the effectiveness of our oracle-based approach on classical RMDP examples from the literature scaling up to thousands of states.},
  author       = {Asadi, Ali and Chatterjee, Krishnendu and Kafshdar Goharshadi, Ehsan and Karrabi, Mehrdad and Shafiee, Ali},
  booktitle    = {Proceedings of the 40th AAAI Conference on Artificial Intelligence},
  issn         = {2374-3468},
  location     = {Singapore, Singapore},
  number       = {43},
  pages        = {36137--36145},
  publisher    = {Association for the Advancement of Artificial Intelligence},
  title        = {{Qualitative analysis of ω-regular objectives on robust MDPs}},
  doi          = {10.1609/aaai.v40i43.40931},
  volume       = {40},
  year         = {2026},
}

@inproceedings{21722,
  abstract     = {Partially observable Markov decision processes (POMDPs) are a central model for uncertainty in sequential decision making. The most basic objective is the reachability objective, where a target set must be eventually visited, and the more general parity objectives can model all omega-regular specifications. For such objectives, the computational analysis problems are the following: (a) qualitative analysis that asks whether the objective can be satisfied with probability 1 (almost-sure winning) or probability arbitrarily close to 1 (limit-sure winning); and (b) quantitative analysis that asks for the approximation of the optimal probability of satisfying the objective. For general POMDPs, almost-sure analysis for reachability objectives is EXPTIME-complete, but limit-sure and quantitative analyses for reachability objectives are undecidable; almost-sure, limit-sure, and quantitative analyses for parity objectives are all undecidable. A special class of POMDPs, called revealing POMDPs, has been studied recently in several works, and for this subclass the almost-sure analysis for parity objectives was shown to be EXPTIME-complete. In this work, we show that for revealing POMDPs the limit-sure analysis for parity objectives is EXPTIME-complete, and even the quantitative analysis for parity objectives can be achieved in EXPTIME.},
  author       = {Asadi, Ali and Chatterjee, Krishnendu and Lurie, David and Saona Urmeneta, Raimundo J},
  booktitle    = {Proceedings of the AAAI Conference on Artificial Intelligence},
  issn         = {2374-3468},
  location     = {Singapore, Singapore},
  number       = {43},
  pages        = {36146--36154},
  publisher    = {Association for the Advancement of Artificial Intelligence},
  title        = {{Revealing POMDPs: Qualitative and quantitative analysis for parity objectives}},
  doi          = {10.1609/aaai.v40i43.40932},
  volume       = {40},
  year         = {2026},
}

@inproceedings{22146,
  abstract     = {We study differentially private model training with stochastic gradient descent under learning rate scheduling and correlated noise. Although correlated noise, in particular via matrix factorizations, has been shown to improve accuracy, prior theoretical work focused primarily on the prefix-sum workload. That workload assumes a constant learning rate, whereas in practice learning rate schedules are widely used to accelerate training and improve convergence. We close this gap by deriving general upper and lower bounds for a broad class of learning rate schedules in both single- and multi-epoch settings. Building on these results, we propose a learning-rate-aware factorization that achieves improvements over prefix-sum factorizations under both MaxSE and MeanSE error metrics. Our theoretical analysis yields memory-efficient constructions suitable for practical deployment, and experiments on CIFAR-10 and IMDB datasets confirm that schedule-aware factorizations improve accuracy in private training.},
  author       = {Kalinin, Nikita and Andersson, Joel D},
  booktitle    = {7th Symposium on Foundations of Responsible Computing},
  isbn         = {9783959774192},
  issn         = {1868-8969},
  keywords     = {differential privacy, machine learning, matrix factorization},
  location     = {Cambridge, MA; United States},
  publisher    = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
  title        = {{Learning rate scheduling with matrix factorization for private training}},
  doi          = {10.4230/LIPIcs.FORC.2026.2},
  volume       = {368},
  year         = {2026},
}

@article{22102,
  abstract     = {Differential privacy (DP) has established itself as one of the standards for ensuring privacy of individual data. However, reasoning about DP is a challenging and error-prone task, hence methods for formal verification and refutation of DP properties have received significant interest in recent years. In this work, we present a novel method for automated formal refutation of є-DP. Our method refutes є-DP by searching for a pair of inputs together with a non-negative function over outputs whose expected value on these two inputs differs by a significant amount. The two inputs and the non-negative function over outputs are computed simultaneously, by utilizing upper expectation supermartingales and lower expectation submartingales from probabilistic program analysis, which we leverage to introduce a sound and complete proof rule for є-DP refutation. To the best of our knowledge, our method is the first method for є-DP refutation to offer the following four desirable features: (1) it is fully automated, (2) it is applicable to stochastic mechanisms with sampling instructions from both discrete and continuous distributions, (3) it provides soundness guarantees, and (4) it provides semi-completeness guarantees. Our experiments show that our prototype tool SuperDP achieves superior performance compared to the state of the art and manages to refute є-DP for a number of challenging examples collected from the literature, including ones that were out of the reach of prior methods.},
  author       = {Chatterjee, Krishnendu and Kafshdar Goharshadi, Ehsan and Zikelic, Dorde},
  issn         = {2475-1421},
  journal      = {Proceedings of the ACM on Programming Languages},
  keywords     = {Static Program Analysis, Differential Privacy, Probabilistic Programming, Martingales},
  number       = {PLDI},
  publisher    = {ACM},
  title        = {{SuperDP: Differential privacy refutation via supermartingales}},
  doi          = {10.1145/3808296},
  volume       = {10},
  year         = {2026},
}

@article{22101,
  abstract     = {Evolutionary biology examines how the genetic and phenotypic composition
of populations changes over time. An important goal is to determine the
fixation probability of a single advantageous mutant that arises in a homogeneous
population of N residents. Many real populations experience environmental
gradients that cause mutations to be beneficial in some spatial
regions but harmful in others. Here, we study the fixation probability of a
mutant placed on a simple one-dimensional spatial structure that experiences
such a gradient. The mutant’s fitness varies linearly from1 − s to 1 + s, whereas
the resident fitness is constant and equal to 1. The existing literature suggests
that such heterogeneity in the mutant’s fitness should lead to a decrease in its
fixation probability. However, in this work, we find that small, non-negligible
gradients (s < 1=√N) substantially increase the fixation probability,while larger
gradients (s > (log N)/√N) substantially decrease it.Moreover, we quantify the
strength of this phenomenon analytically and we precisely delimit the range of
the gradients for which it occurs. Our computer simulations closely match
those findings. Altogether, our results indicate that subjecting a simple
population structure to natural environmental conditions can produce strong
counterintuitive effects.},
  author       = {Svoboda, Jakub and Nemati, Hossein and Tkadlec, Josef and Kaveh, Kamran and Chatterjee, Krishnendu},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{The effect of the fitness gradient on fixation probability}},
  doi          = {10.1038/s41467-026-71777-2},
  volume       = {17},
  year         = {2026},
}

@article{21948,
  abstract     = {The cerebral cortex comprises diverse neuron and glial cell types generated by radial glial progenitors (RGPs) during development. Although RGPs broadly differentiate according to temporally and spatially regulated molecular logics, the lineage hierarchies linking individual progenitors to defined cell (sub)types are not well understood. Clone-resolved transcriptomics, combining molecular barcoding and single-cell RNA sequencing, allow high-resolution lineage tracing at the single-clone/cell level across different species and models. In this mini-review, we synthesize recent advances in this field, uncovering unexpected lineage relationships in the developing brain, with a particular focus on the cerebral cortex. We further highlight new insights into species-specific differences in the developmental programs generating cell-type diversity, linking changes in clonal architecture to lineage diversification during cortical evolution.},
  author       = {Varela Martínez, Irene and Pipicelli, Fabrizia and Hippenmeyer, Simon},
  issn         = {1879-0380},
  journal      = {Current Opinion in Genetics & Development},
  publisher    = {Elsevier},
  title        = {{Tracing cell lineages in the developing brain: Insights from mosaic analysis and clone-resolved transcriptomics}},
  doi          = {10.1016/j.gde.2026.102487},
  volume       = {99},
  year         = {2026},
}

@misc{22134,
  abstract     = {This artifact provides the source code, benchmarks, and scripts necessary to build and reproduce the experimental results for `SuperDP` (Accepted at PLDI 2026). It also includes instructions for running the tool on user-provided inputs.},
  author       = {Chatterjee, Krishnendu and Kafshdar Goharshadi, Ehsan and Zikelic, Dorde},
  publisher    = {Zenodo},
  title        = {{SuperDP: Differential Privacy Refutation via Supermartingales}},
  doi          = {10.5281/ZENODO.18930113},
  year         = {2026},
}

@article{22637,
  abstract     = {The distribution of entanglement across distant qubits is a central challenge for the operation of scalable quantum computers and large-scale quantum networks. Existing approaches rely on deterministic state transfer, or probabilistic protocols that require active control or measurements and postselection. Here, we demonstrate a fundamentally different, fully autonomous process, where two remote qubits are entangled through their coupling to a quantum-correlated photonic reservoir. In our experiment, a Josephson parametric converter produces a Gaussian, continuous-variable entangled state of propagating microwave fields that drives two spatially separated superconducting transmon qubits into a stationary, discrete-variable entangled state. We also show how qubit tomography unlocks a direct and sensitive verification of two-mode squeezing in the microwave domain. These results establish networks of qubits interfaced with distributed continuous-variable entangled states as a powerful platform for foundational studies and quantum-technology applications.},
  author       = {Andres Juanes, Alejandro and Agustí, J. and Sett, Riya and Redchenko, Elena and Kapoor, Lucky and Hawaldar, Samarth and Rabl, P. and Fink, Johannes M},
  issn         = {2160-3308},
  journal      = {Physical Review X},
  number       = {3},
  publisher    = {American Physical Society},
  title        = {{Distributing stationary qubit entanglement through a nonlocal squeezed reservoir}},
  doi          = {10.1103/r4jt-j39w},
  volume       = {16},
  year         = {2026},
}

@article{22711,
  abstract     = {When charge flows through a molecular circuit, it induces a magnetic field that allows the circuit to behave as a nanoscale electromagnet. However, in single-molecule circuits this magnetic field is usually weak. Here we show that radially π-conjugated carbon structures can support amplified circulating currents that generate local magnetic fields. Within tight-binding and density functional theory (DFT) frameworks, we first study cycloparaphenylene (CPP) junctions where both electrodes are attached to the same phenylene unit on the nanohoop. We observe an energy-dependent ring current component that traverses the whole macrocycle by mapping the local current density. Importantly, we find that destructive interference near degenerate resonances can reverse the ring current direction and amplify it strongly relative to the source–drain current. We show that this interference-driven design principle is general, and also carries over to C60 junctions. In fullerene, lower-lying degenerate resonances are more easily accessible through electrostatic gating, reaching a magnetic field of 14.2 mT under a 100 mV source–drain bias. This work thus provides new insights into ring currents in radially π-conjugated carbon structures and highlights their potential as design platforms for single-molecule electromagnets.},
  author       = {Shi, Wanzhuo and Korytár, Richard and Evers, Ferdinand and Tovar, John D. and Venkataraman, Latha},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{Designing effective single-molecule electromagnets with radially π-conjugated carbon structures}},
  doi          = {10.1038/s41467-026-74365-6},
  volume       = {17},
  year         = {2026},
}

@phdthesis{22735,
  author       = {Lin, Peipeng},
  isbn         = {978-3-99078-088-6},
  issn         = {2663-337X},
  pages        = {88},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Calibrating the teacher synapse: Mechanisms and functional significance of presynaptic inhibition at hippocampal mossy fiber synapses}},
  doi          = {10.15479/AT-ISTA-22735},
  year         = {2026},
}

@inproceedings{22916,
  abstract     = {In the imprecise geometry model, the input is a family of regions F = (R₁, R₂, …,R_n), each containing a point p_i ∈ R_i. The task is then to compute some function of the points p₁,p₂,… p_n, in our case an implicit representation of their Pareto front. To this end, one may query a region R_i to retrieve its contained point p_i ∈ R_i. In this model, efficiency is interpreted in two ways: minimizing (i) the number of retrievals, and (ii) the computation time both for preprocessing, and the execution of the query stage, i.e. for computing which points to query and constructing the output. 
We present an algorithm to construct (an implicit representation of) the Pareto front for possibly overlapping rectangles, that is instance-optimal with respect to the number of retrievals. This means that for every fixed input (F, P), there is no algorithm that retrieves asymptotically fewer regions to compute the output. This is a strong algorithmic quality, as it means that our algorithm is competitive even to clairvoyant algorithms which only have to verify the correctness of a correct guess. In terms of algorithmic running time, instance-optimality is provably unobtainable. We instead present an algorithm which is within a log n-factor of instance optimality. This generalizes earlier results which assumed the regions to not overlap, at only a minor cost in running time. 
For unit squares, we present an algorithm that is not only instance optimal in the number of retrievals, but also universally optimal in terms of running time. This means that for any fixed set of regions F, no algorithm has a better worst-case running time for all possible point sets P. Thus, this work presents the first universally optimal algorithm for overlapping planar input. Compared to previous work, our result improves the degree to which the input regions may overlap, the preprocessing time, the number of retrievals, and the running time.},
  author       = {De Berg, Sarita and Bække, Nynne Maria Foldager and Eriksen, Frida Astrup and Van Der Hoog, Ivor and Rotenberg, Eva and Rutschmann, Daniel P},
  booktitle    = {34th Annual European Symposium on Algorithms},
  isbn         = {9783959774451},
  issn         = {1868-8969},
  keywords     = {Pareto front, imprecise geometry, instance optimality, universal optimality, preprocessing model, partial information},
  location     = {L’Aquila, Italy},
  publisher    = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
  title        = {{Instance optimal and universally optimal bounds for imprecise pareto fronts}},
  doi          = {10.4230/LIPIcs.ESA.2026.106},
  volume       = {388},
  year         = {2026},
}

@article{22816,
  abstract     = {The Galactic Be star binary MWC 656 was long considered the only known Be star+black hole (BH) system, making it a critical
benchmark for models of massive binary evolution and for the expected X-ray emission of Be+BH binaries. However, recent dynamical measurements cast doubt on the presence of a BH companion. We present new multi-epoch ultraviolet spectroscopy from the
Hubble Space Telescope, combined with high-resolution optical spectra, to reassess the nature of the companion. The far-ultraviolet
spectra reveal high-ionisation features – including prominent N v and He ii lines – which are absent in the spectra of normal Be stars
and are indicative of a hot, luminous companion. Spectral modelling shows that these features cannot originate from the Be star or
from an accretion disc around a compact object. Instead, we find that the data are best explained by a hot (Teff ≈ 85 kK), compact,
hydrogen-deficient star with strong wind signatures, consistent with an intermediate-mass stripped star. Our revised orbital solution
and composite spectroscopic modelling yield a companion mass of M2 = 1.48+0.55
−0.46 M, definitively ruling out a BH and disfavouring a
white dwarf. MWC 656 thus joins the growing class of Be + stripped star binaries. The system’s unusual properties – including a high
companion temperature and wind strength – extend the known parameter space of such binaries. The continued absence of confirmed
OBe+BH binaries in the Galaxy highlights a growing tension with population synthesis models.},
  author       = {Müller-Horn, Johanna and Ramachandran, Varsha and El-Badry, Kareem and Sander, Andreas A.C. and Bodensteiner, Julia K and Gies, Douglas R. and Götberg, Ylva Louise Linsdotter and Rivinius, Thomas and Shenar, Tomer and Schösser, Elisa C. and Wang, Luqian and Bieryla, Allyson and Buchhave, Lars A. and Latham, David W.},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  publisher    = {EDP Sciences},
  title        = {{Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star+black hole candidate MWC 656}},
  doi          = {10.1051/0004-6361/202557960},
  volume       = {708},
  year         = {2026},
}

@article{21450,
  abstract     = {Stellar wind mass loss of massive stars is often assumed to depend on their metallicity Z. Therefore, evolutionary models predict that massive stars in lower-Z environments are able to retain more of their hydrogen-rich layers and evolve into brighter cool supergiants (cool SGs; Teff < 7 kK). Surprisingly, in galaxies in the metallicity range 0.2 ≲ Z/Z⊙ ≲ 1.5, previous studies have not found a metallicity dependence on the upper luminosity limit Lmax of cool SGs. Here, we add four galaxies to the sample studied for this purpose with data from the Hubble Space Telescope and the James Webb Space Telescope (JWST). Observations of the extremely metal-poor dwarf galaxy I Zw 18 from JWST allow us to extend the studied metallicity range down to Z/Z⊙ ≈ 1/40. For cool SGs in all studied galaxies, including I Zw 18, we find a constant value of Lmax ≈ 105.6 L⊙, similar to literature results for 0.2 ≲ Z/Z⊙ ≲ 1.5. In I Zw 18 and the other studied galaxies, the presence of Wolf-Rayet stars has been previously inferred. Although we cannot rule out that some of them become intermediate-temperature objects, this paints a picture in which evolved stars with L > 105.6 L⊙ burn helium as hot, helium-rich stars down to extremely low metallicity. We argue that metallicity-independent late-phase mass loss would be the most likely mechanism responsible for this. Regardless of the exact stripping mechanism (winds or, for example, binary interaction), for the Early Universe our results imply a limitation on black hole masses and a contribution of stars born with M ≳ 30 M⊙ to its surprisingly strong nitrogen enrichment. We propose a scenario in which single stars at low metallicity emit sufficiently hard ionizing radiation to produce He II and C IV lines. In this scenario, late-phase metallicity-independent mass loss produces hot, helium-rich stars. Due to the well-understood metallicity dependence on the radiation-driven winds of hot stars, a window of opportunity would open below 0.2 Z⊙, where self-stripped helium-rich stars can exist without dense Wolf-Rayet winds that absorb hard ionizing radiation.},
  author       = {Schootemeijer, Abel and Götberg, Ylva Louise Linsdotter and Langer, Norbert and Bortolini, Giacomo and Hirschauer, Alec S. and Patrick, Lee},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  publisher    = {EDP Sciences},
  title        = {{A constant upper luminosity limit of cool supergiant stars down to the extremely low metallicity of I Zw 18}},
  doi          = {10.1051/0004-6361/202557675},
  volume       = {707},
  year         = {2026},
}

@article{21997,
  abstract     = {The massive binary common envelope (CE) phase plays a pivotal role in the formation of close black hole (BH)/neutron star binaries, yet significant uncertainties remain in our understanding of this process. In this study, we aim to constrain the massive binary CE phase by systematically reconstructing three observed BH X-ray binaries (BHXBs): GRO J1655-40, SAX J1819.3-2525, and 4U 1543-47. Through comprehensive binary evolution simulations and parametric supernova modeling, we establish lower limits for the CE efficiency parameters under different energy considerations within the standard energy formalism. Specifically, we derive minimum values for three cases: α0.5U and αU, representing CE efficiencies with half and all of the internal energy contributing to the envelope ejection, respectively, and αH, accounting for the envelope’s enthalpy. Our analysis reveals that the self-consistent formation of these three BHXBs requires CE efficiency parameters satisfying α0.5U ≳ 6.7, αU ≳ 4.2, and αH ≳ 1.7. Notably, we find no viable solutions with CE efficiency values below unity, even when considering the most extreme scenarios, in which the envelope binding energy is significantly reduced through enthalpy inclusion. Our results strongly imply that either additional energy sources are required or the formalism itself must be revised. Furthermore, we quantitatively assess the impact of BH natal kicks on our results. A key finding is that 4U 1543-47’s formation requires substantial natal kicks (≳50 km s−1), as lower kick velocities are incompatible with isolated binary evolution.},
  author       = {Li, Zhenwei and Wei, Dandan and Jia, Shi and Chen, Hailiang and Ge, Hongwei and Chen, Zhuo and Zhang, Yangyang and Chen, Xuefei and Han, Zhanwen},
  issn         = {1538-4357},
  journal      = {The Astrophysical Journal},
  number       = {1},
  publisher    = {IOP Publishing},
  title        = {{A path to constraints on common envelope ejection in massive binaries: Full evolutionary reconstruction of three Black Hole X-ray binaries}},
  doi          = {10.3847/1538-4357/ae66fd},
  volume       = {1004},
  year         = {2026},
}