arXiv subjects

Joshua Berger

Publications and source records attributed to Joshua Berger.

At least 19 recordsLinked to original sources

arXiv2026

Are LLM-based Chatbots Good Enough to Support Computer Science Students in Multiple-Choice Exercises?

Chatbots based on large language models (LLMs) are increasingly adopted for information retrieval, text generation, and writing assistance. In educational settings, their use is also rapidly increasing. Students leverage these systems to complete tasks, access information, and support learning. However, the role of LLM-based chatbots in supporting learning and assessment in university-level computer science education is still underexplored. To address this gap, we investigate the performance of several LLM-based chatbots in solving multiple-choice questions (MCQs) at the university level and evaluate their capabilities to assist student learning. We developed 70 MCQs for a university lecture on interactive visual data analysis and evaluated the chatbots' performance using different prompt designs. We further compared the results with students' performance. Finally, we conducted a user study in two lectures (interactive visual data analysis, computer vision) to investigate how chatbot-generated answers and explanations affect students' performance. The chatbot performance showed significant differences between smaller models and GPT-4o and GPT-5 models, which achieved the best results. The results of the user study show that presenting ChatGPT answers together with an explanation does not improve students' performance in general.

cs.HC↗

arXiv2025

Galactic magnetic fields seeded by ultralight dark photons

In this work, we show that ultralight dark photons, which couple to the Standard Model photon through kinetic mixing, can potentially source galactic scale magnetic fields. Although these magnetic fields would be too weak to detect at present in galaxies due to plasma screening effects, we show that dark photons can provide the seed magnetic field strength ($10^{-20}$ G) required for dynamo amplification in galaxies. Such dynamo-amplified magnetic fields are consistent with observations of $\mu$G strength galactic magnetic fields.

hep-ph↗

arXiv2025

Resonant Scattering of Boosted Dark Matter

We develop a simulation within GENIE of the excitation of baryonic resonances by boosted dark matter. This work completes the simulation of all scattering modes for dark matter entering a detector at relativistic speeds. At some boosts, resonant scattering can contribute over 30% to the scattering rate. This channel offers a potentially powerful probe of the isospin structure of dark matter interactions via the relative prominence of the isospin-changing $\Delta$ resonance. We study the estimated sensitivity of large volume detectors such as DUNE, Hyper-Kamiokande, and JUNO to all dark matter scattering modes and demonstrate the expected improvement in sensitivity when resonant scattering is included.

hep-ph↗

arXiv2025

Cosmological Histories in Neutrino Portal Dark Matter

We explore the diverse cosmological histories of a dark sector that is connected to the Standard Model (SM) via a Dirac sterile neutrino. The dark sector consists of a complex scalar and a Dirac fermion dark matter (DM) candidate protected by a global $U(1)$ stabilizing symmetry. Assuming the dark sector has negligible initial abundance and is populated from reactions in the SM thermal plasma during the radiation era, we show that the cosmological histories of the dark sector fall into four qualitatively distinct scenarios, each one characterized by the strengths of the portal couplings involving the sterile neutrino mediator. By solving Boltzmann equations, both semi-analytically and numerically, we explore these thermal histories and transitions between them in detail, including the time evolution of the temperature of the dark sector and the number densities of its ingredients. We also discuss how these various histories may be probed by cosmology, direct detection, indirect detection, collider searches, and electroweak precision tests.

hep-ph↗

arXiv2025

Enhancing the Learning Experience: Using Vision-Language Models to Generate Questions for Educational Videos

Web-based educational videos offer flexible learning opportunities and are becoming increasingly popular. However, improving user engagement and knowledge retention remains a challenge. Automatically generated questions can activate learners and support their knowledge acquisition. Further, they can help teachers and learners assess their understanding. While large language and vision-language models have been employed in various tasks, their application to question generation for educational videos remains underexplored. In this paper, we investigate the capabilities of current vision-language models for generating learning-oriented questions for educational video content. We assess (1) out-of-the-box models' performance; (2) fine-tuning effects on content-specific question generation; (3) the impact of different video modalities on question quality; and (4) in a qualitative study, question relevance, answerability, and difficulty levels of generated questions. Our findings delineate the capabilities of current vision-language models, highlighting the need for fine-tuning and addressing challenges in question diversity and relevance. We identify requirements for future multimodal datasets and outline promising research directions.

cs.CV↗

arXiv2024

Dark Matter Raining on DUNE and Other Large Volume Detectors

Direct detection is a powerful means of searching for particle physics evidence of dark matter (DM) heavier than about a GeV with $\mathcal O(kiloton)$ volume, low-threshold detectors. In many scenarios, some fraction of the DM may be boosted to large velocities enhancing and generally modifying possible detection signatures. We investigate the scenario where 100% of the DM is boosted at the Earth due to new attractive long-range forces. This leads to two main improvements in detection capabilities: 1) the large boost allows for detectable signatures of DM well below a GeV at large-volume neutrino detectors, such as DUNE, Super-K, Hyper-K, and JUNO, as possible DM detectors, and 2) the flux at the Earth's surface is enhanced by a focusing effect. In addition, the model leads to a significant anisotropy in the signal with the DM flowing dominantly vertically at the Earth's surface instead of the typical approximately isotropic DM signal. We develop the theory behind this model and also calculate realistic constraints using a detailed GENIE simulation of the signal inside detectors.

hep-ph↗

arXiv2024

Sensitivity to Kaon Decays to ALPs at Fixed Target Experiments

We study the sensitivity of fixed target experiments to hadronically-coupled axion like particles (ALPs) produced in kaon decays, with a particular emphasis on current and upcoming short-baseline neutrino experiments. We demonstrate that below the kaon decay mass threshold ($m_a < m_K - m_\pi$) kaon decay is the dominant production mechanism for ALPs at neutrino experiments, larger by many orders of magnitude than production in psuedo-scalar mixing. Such axions can be probed principally by the di-photon and di-muon final states. In the latter case, even if the axion does not couple to muons at tree level, such a coupling is induced by the renormalization group flow from the UV scale. We reinterpret prior results by CHARM and MicroBooNE through these channels and show that they constrain new areas of heavy axion parameter space. We also show projections of the sensitivity of the SBN and DUNE experiments to axions through these channels, which reach up to multiple decades higher in the axion decay constant beyond existing constraints. DUNE projects to have a sensitivity competitive with other world-leading upcoming experiments.

hep-ph↗

arXiv2023

Axion Electrodyanmics in the Presence of Current Sources

Axions are among the most sought-after candidates for dark matter. In the ultralight regime, they could help alleviate puzzles in small scale cosmology. Searches for a halo of axion dark matter rely on the electromagnetic response to a magnetic field. In this work, we resolve a number of issues in the determination of this response by carefully solving Maxwell's equations in the presence of an axion background. We find that the electric field induced by a magnetic field in an axion background is significant and unsuppressed by the size of the experiment.

hep-ph↗

arXiv2023

Probing Exotic Phases Via Stochastic Gravitational Wave Spectra

Stochastic backgrounds of gravitational waves (GWs) from the pre-BBN era offer a unique opportunity to probe the universe beyond what has already been achieved with the Cosmic Microwave Background (CMB). If the source is short in duration, the low frequency tail of the resulting GW spectrum follows a universal frequency scaling dependent on the equation of state of the universe when modes enter the horizon. We demonstrate that the distortion of the equation of state due to massive particles becoming non-relativistic can lead to an observable dip in the GW spectrum. To illustrate this effect, we consider a first order chiral symmetry breaking phase transition in the weak-confined Standard Model (WCSM). The model features a large number of pions and mostly elementary fermions with masses just below the critical temperature for the phase transition. These states lead to a 20$\%$ dip in the GW power. We find potential sensitivity to the distortions in the spectrum to future GW detectors such as LISA, DECIGO, BBO, and $\mu$Ares.

hep-ph↗

arXiv2023

Dark Matter Induced Nucleon Decay Signals in Mesogenesis

We introduce and study the first class of signals that can probe the dark matter in Mesogenesis which will be observable at current and upcoming large volume neutrino experiments. The well-motivated Mesogenesis scenario for generating the observed matter-anti-matter asymmetry necessarily has dark matter charged under baryon number. Interactions of these particles with nuclei can induce nucleon decay with kinematics differing from sponanteous nucleon decay. We calculate the rate for this process and develop a simulation of the signal that includes important distortions due to nuclear effects. We estimate the sensitivity of DUNE, Super-Kamiokande, and Hyper-Kamiokande to this striking signal.

hep-ph↗

arXiv2022

Dark Sector Studies with Neutrino Beams

An array of powerful neutrino-beam experiments will study the fundamental properties of neutrinos with unprecedented precision in the coming years. Along with their primary neutrino-physics motivations, there has been growing recognition that these experiments can carry out a rich program of searches for new, light, weakly-coupled particles that are part of a dark sector. In this white paper, we review the diverse theoretical motivations for dark sectors and the capabilities of neutrino beam experiments to probe a wide range of models and signatures. We also examine the potential obstacles that could limit these prospects and identify concrete steps needed to realize an impactful dark sector search program in this and coming decades.

hep-ph↗

arXiv2022

IceCube at the Frontier of Macroscopic Dark Matter Direct Detection

For a class of macroscopic dark matter models, inelastic scattering of dark matter off a nucleus can generate electromagnetic signatures with GeV-scale energy. The IceCube detector, with its kilometer-scale size, is ideal for directly detecting such inelastic scattering. Based on the slow particle trigger for the DeepCore detector, we perform a detailed signal and background simulation to estimate the discovery potential. For order 1 GeV deposited energy in each interaction, we find that IceCube can probe the dark matter masses up to one gram.

hep-ph↗

arXiv2022

Laboratory constraints on ultralight axion-like particles from precision atomic spectroscopy

Ultralight bosonic dark matter has come under increasing scrutiny as a dark matter candidate that has the potential to resolve puzzles in astronomical observation. We demonstrate that high-precision measurements of time variation in the frequency ratios of atomic transitions achieves leading sensitivity to ultralight axion-like particle dark matter at low masses. These bounds are the first laboratory-based bounds on this class of dark matter models. We propose further measurements that could enhance sensitivity to ultralight axion-like particles.

hep-ph↗

arXiv2022

Snowmass2021 Cosmic Frontier White Paper: Ultraheavy particle dark matter

We outline the unique opportunities and challenges in the search for "ultraheavy" dark matter candidates with masses between roughly $10~{\rm TeV}$ and the Planck scale $m_{\rm pl} \approx 10^{16}~{\rm TeV}$. This mass range presents a wide and relatively unexplored dark matter parameter space, with a rich space of possible models and cosmic histories. We emphasize that both current detectors and new, targeted search techniques, via both direct and indirect detection, are poised to contribute to searches for ultraheavy particle dark matter in the coming decade. We highlight the need for new developments in this space, including new analyses of current and imminent direct and indirect experiments targeting ultraheavy dark matter and development of new, ultra-sensitive detector technologies like next-generation liquid noble detectors, neutrino experiments, and specialized quantum sensing techniques.

hep-ph↗

arXiv2021

Nucleus Capture by Macroscopic Dark Matter

For a class of macroscopic dark matter with a large interaction strength with Standard Model particles, a nucleus could be captured by the dense, heavy dark matter as it traverses ordinary material. The radiated photon carries most of the binding energy and is a characteristic signature for dark matter detection. We develop analytic formulas and present numerical results for this radiative capture process in the low energy, non-dipole limit. Large-volume neutrino detectors like NO$ν$A, JUNO, DUNE and Super(Hyper)-K may detect multi-hit or single-hit radiative capture events and can search for dark matter up to one gram in mass.

hep-ph↗

arXiv2021

Catalyzed Baryogenesis

A novel mechanism, "catalyzed baryogenesis," is proposed to explain the observed baryon asymmetry in our universe. In this mechanism, the motion of a ball-like catalyst provides the necessary out-of-equilibrium condition, its outer wall has CP-violating interactions with the Standard Model particles, and its interior has baryon number violating interactions. We use the electroweak-symmetric ball model as an example of such a catalyst. In this model, electroweak sphalerons inside the ball are active and convert baryons into leptons. The observed baryon number asymmetry can be produced for a light ball mass and a large ball radius. Due to direct detection constraints on relic balls, we consider a scenario in which the balls evaporate, leading to dark radiation at testable levels.

hep-ph↗

arXiv2021

Inelastic Dark Matter at the Fermilab Short Baseline Neutrino Program

We study the sensitivity of the Fermilab Short-Baseline Neutrino (SBN) experiments, MicroBooNE, ICARUS, and SBND, to MeV- to GeV-scale inelastic dark matter interacting through a dark photon mediator. These models provide interesting scenarios of light thermal dark matter, which, while challenging to probe with direct and indirect detection experiments, are amenable to accelerator-based searches. We consider production of the dark sector states with both the Fermilab Booster 8 GeV and NuMI 120 GeV proton beams and study the signatures of scattering and decay of the heavy excited dark state in the SBN detectors. These distinct signatures probe complementary regions of parameter space. All three experiments will be able to cover new ground, with an excellent near-term opportunity to search for cosmologically motivated targets explaining the observed dark matter abundance.

hep-ph↗

arXiv2021

Muon g-2 in Lepton Portal Dark Matter

The Lepton Portal Dark Matter model, in which dark matter states only coupling to the charged leptons, can explain the excess of the muon anomalous magnetic moment measured by the Muon $g - 2$ experiment. In this paper, we demonstrate that real, charge-neutral scalar dark matter with a large number of internal degrees of freedom and a mass approximately degenerate with the charged fermionic mediator state can accommodate the $(g - 2)_μ$ excess. The model remains consistent with the dark matter relic abundance, direct detection, and indirect detection constraints. The dark matter and its charged fermion partner masses are constrained to be below around 200 GeV. The high-luminosity LHC and future lepton colliders, as well as indirect searches at CTA and GAMMA-400, can test this scenario.

hep-ph↗