arXiv subjects

R. Banerjee

Publications and source records attributed to R. Banerjee.

At least 19 recordsLinked to original sources

arXiv2026

Quantifying collision-driven mass loss in supermassive star formation: the role of stellar structure and accretion

Observations of high-redshift galaxies with JWST have renewed interest in scenarios where supermassive stars form via runaway stellar collisions in dense clusters, yet the impact of collision-driven mass loss on their growth remains uncertain. In this work, we perform a post-processing analysis of 3D hydrodynamical simulations of the formation of a supermassive star, applying an analytic mass-loss prescription to stellar collisions while exploring different assumptions for the internal stellar structure. We consider a polytropic main-sequence model, a semi-analytic accreting protostar model, and structures derived from stellar evolution calculations. We find that the cumulative mass-loss fraction depends sensitively on the adopted stellar structure, ranging from $\lesssim 10-25\%$ for more compact configurations to $\gtrsim 30-40\%$ for more extended protostellar models. The importance of mass loss further depends on the dynamical state of the system, including the ratio of stellar velocity dispersion to the stellar surface escape velocity. We find significant uncertainty depending on the prescription used. As a result, collision-driven mass loss could significantly limit the growth of the central object, at least in some cases. Overall, our results indicate that uncertainties in the internal structure of rapidly accreting protostars represent a major source of systematic uncertainty and must be better constrained to robustly assess the viability of runaway-collision pathways for forming massive black hole seeds.

astro-ph.GA↗

arXiv2026

Magnetic fields in extreme primordial halos: turbulent collapse and implications for early quasar formation

It is sometimes suggested that the most massive quasars at high redshift may have formed from rare high-sigma peaks in the cosmic density field. We explore here the evolution in a massive primordial halo corresponding to one of these rare sigma peaks, employing cosmological high-resolution magneto-hydrodynamical zoom-in simulations with initial field strength of $10^{-14}-10^{-8}$ G. The dark matter halo forms at the intersection of strongly convergent flows, leading to the formation of highly supersonic turbulence already on intergalactic scales, with turbulent Mach numbers of order $10-20$ also within the halo. Turbulent magnetic field amplification has never been explored in this regime and we therefore investigate whether this gives rise to effects similar to those observed in more typical halos. While the weaker initial field is somewhat more strongly amplified as a result of the shear flows, overall the evolution in the different simulations is rather similar and the flows are dominated by supersonic turbulence. We show in particular that the turbulent Jeans mass always dominates over the thermal and magnetic Jeans masses, and only on scales of $10^{-2}-10$ pc, the magnetic Jeans mass may become comparable to the thermal one. Our simulations thus strongly suggest the evolution to be dominated by the large-scale dynamics. As established in previous work, we thus expect the formation of central massive objects of a few times $10^4$ M$_\odot$ also in the presence of magnetic fields. The situation is somewhat different from more typical atomic cooling halos, where previous results have indicated a larger relevance of the magnetic Jeans mass on intermediate scales, potentially enhancing the mass of the massive object.

astro-ph.GA↗

arXiv2026

Coulomb blockade in microscopic material defects as a source of decoherence and noise in solid-state quantum circuits

A critical limitation of solid-state quantum devices arises from the materials from which they are fabricated: uncontrolled surfaces, interfaces, and structural imperfections introduce numerous sources of loss and decoherence. Despite extensive efforts, linking these decoherence mechanisms to their microscopic material origins -- essential for developing effective mitigation strategies -- remains an outstanding challenge that has slowed coherence improvements. Here, using scanning gate microscopy on live superconducting circuits we identify a previously unrecognised decoherence mechanism originating from Coulomb blockade and microwave-driven charge tunnelling in metallic grains. Such grains are ubiquitous in thin-film devices fabricated by standard lithography processes. By characterising multiple defects across different devices, we find such defects to be as common and as debilitating to device performance as two-level system (TLS) defects, while originating from a fundamentally different physical mechanism. Importantly, conventional characterisation techniques would misattribute this loss to other, microwave power-independent processes. Our observations thus reveal a widespread source of decoherence in superconducting circuits, challenging the prevailing paradigm that coherence lifetimes are primarily limited by TLS defects. Eliminating metallic grains during fabrication provides a clear and practical route to suppress this mechanism, offering a pathway towards improved coherence and reduced noise in microwave-based solid-state quantum devices.

quant-ph↗

arXiv2026

Closing the Loop: Deploying Auto-Generating Digital Twins for Particle Accelerators

The simulation of a physical system in a virtual replica, known as a digital twin, is a useful way to interrogate the system non-invasively, providing the ability to perform predictive maintenance and surveillance, and to investigate potential novel configurations without perturbing the system. This article presents the implementation of an auto-generating digital twin architecture for particle accelerators: a virtual control system is generated to mirror the physical accelerator hardware, and used to update a simulation model which then feeds back the results into virtual diagnostics. All of the information about the accelerator lattice is cascaded down from a ground source of truth, removing any ambiguity about the naming of parameters between the simulation model and the virtual hardware. This design is modular and extensible, allowing researchers from different institutions to use their own models (for example, a machine learning model) and accelerator lattices while maintaining the overall structural coherence of the digital twin. This architecture has been tested for three accelerator facilities \textendash~CLARA, the ISIS injector, and the proposed UK XFEL \textendash~and aims to provide the foundation for a collaborative community effort in the development of shared technology towards a generic digital twin solution.

physics.acc-ph↗

arXiv2025

Exciton-Polariton hybrid skin-topological states

The non Hermitian skin effect, where bulk states accumulate at system boundaries, challenges the conventional bulk boundary correspondence. Here we propose a scheme to realize hybrid skin topological states in exciton polariton honeycomb lattices by introducing sublattice dependent gain and loss. This non Hermiticity couples with the intrinsic topological edge modes, leading to relocalization of edge states. We show two distinct regimes: hybrid skin Chern states with switchable localization controlled by TE TM splitting , and hybrid skin antichiral states which preserves the spin polarized property. Our results bridge polariton spin physics and non-Hermitian topology, opening routes toward controllable non reciprocal and spin polarized transport.

cond-mat.mes-hall↗

arXiv2025

DUNE Software and Computing Research and Development

The international collaboration designing and constructing the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF) has developed a two-phase strategy toward the implementation of this leading-edge, large-scale science project. The ambitious physics program of Phase I and Phase II of DUNE is dependent upon deployment and utilization of significant computing resources, and successful research and development of software (both infrastructure and algorithmic) in order to achieve these scientific goals. This submission discusses the computing resources projections, infrastructure support, and software development needed for DUNE during the coming decades as an input to the European Strategy for Particle Physics Update for 2026. The DUNE collaboration is submitting four main contributions to the 2026 Update of the European Strategy for Particle Physics process. This submission to the 'Computing' stream focuses on DUNE software and computing. Additional inputs related to the DUNE science program, DUNE detector technologies and R&D, and European contributions to Fermilab accelerator upgrades and facilities for the DUNE experiment, are also being submitted to other streams.

physics.data-an↗

arXiv2025

European Contributions to Fermilab Accelerator Upgrades and Facilities for the DUNE Experiment

The Proton Improvement Plan (PIP-II) to the FNAL accelerator chain and the Long-Baseline Neutrino Facility (LBNF) will provide the world's most intense neutrino beam to the Deep Underground Neutrino Experiment (DUNE) enabling a wide-ranging physics program. This document outlines the significant contributions made by European national laboratories and institutes towards realizing the first phase of the project with a 1.2 MW neutrino beam. Construction of this first phase is well underway. For DUNE Phase II, this will be closely followed by an upgrade of the beam power to > 2 MW, for which the European groups again have a key role and which will require the continued support of the European community for machine aspects of neutrino physics. Beyond the neutrino beam aspects, LBNF is also responsible for providing unique infrastructure to install and operate the DUNE neutrino detectors at FNAL and at the Sanford Underground Research Facility (SURF). The cryostats for the first two Liquid Argon Time Projection Chamber detector modules at SURF, a contribution of CERN to LBNF, are central to the success of the ongoing execution of DUNE Phase I. Likewise, successful and timely procurement of cryostats for two additional detector modules at SURF will be critical to the success of DUNE Phase II and the overall physics program. The DUNE Collaboration is submitting four main contributions to the 2026 Update of the European Strategy for Particle Physics process. This paper is being submitted to the 'Accelerator technologies' and 'Projects and Large Experiments' streams. Additional inputs related to the DUNE science program, DUNE detector technologies and R&D, and DUNE software and computing, are also being submitted to other streams.

physics.acc-ph↗

arXiv2025

The DUNE Science Program

The international collaboration designing and constructing the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF) has developed a two-phase strategy for the implementation of this leading-edge, large-scale science project. The 2023 report of the US Particle Physics Project Prioritization Panel (P5) reaffirmed this vision and strongly endorsed DUNE Phase I and Phase II, as did the previous European Strategy for Particle Physics. The construction of DUNE Phase I is well underway. DUNE Phase II consists of a third and fourth far detector module, an upgraded near detector complex, and an enhanced > 2 MW beam. The fourth FD module is conceived as a 'Module of Opportunity', aimed at supporting the core DUNE science program while also expanding the physics opportunities with more advanced technologies. The DUNE collaboration is submitting four main contributions to the 2026 Update of the European Strategy for Particle Physics process. This submission to the 'Neutrinos and cosmic messengers', 'BSM physics' and 'Dark matter and dark sector' streams focuses on the physics program of DUNE. Additional inputs related to DUNE detector technologies and R&D, DUNE software and computing, and European contributions to Fermilab accelerator upgrades and facilities for the DUNE experiment, are also being submitted to other streams.

hep-ex↗

arXiv2025

The DUNE Phase II Detectors

The international collaboration designing and constructing the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF) has developed a two-phase strategy for the implementation of this leading-edge, large-scale science project. The 2023 report of the US Particle Physics Project Prioritization Panel (P5) reaffirmed this vision and strongly endorsed DUNE Phase I and Phase II, as did the previous European Strategy for Particle Physics. The construction of DUNE Phase I is well underway. DUNE Phase II consists of a third and fourth far detector module, an upgraded near detector complex, and an enhanced > 2 MW beam. The fourth FD module is conceived as a 'Module of Opportunity', aimed at supporting the core DUNE science program while also expanding the physics opportunities with more advanced technologies. The DUNE collaboration is submitting four main contributions to the 2026 Update of the European Strategy for Particle Physics process. This submission to the 'Detector instrumentation' stream focuses on technologies and R&D for the DUNE Phase II detectors. Additional inputs related to the DUNE science program, DUNE software and computing, and European contributions to Fermilab accelerator upgrades and facilities for the DUNE experiment, are also being submitted to other streams.

physics.ins-det↗

arXiv2025

Neutrino Interaction Vertex Reconstruction in DUNE with Pandora Deep Learning

The Pandora Software Development Kit and algorithm libraries perform reconstruction of neutrino interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at the Deep Underground Neutrino Experiment, which will operate four large-scale liquid argon time projection chambers at the far detector site in South Dakota, producing high-resolution images of charged particles emerging from neutrino interactions. While these high-resolution images provide excellent opportunities for physics, the complex topologies require sophisticated pattern recognition capabilities to interpret signals from the detectors as physically meaningful objects that form the inputs to physics analyses. A critical component is the identification of the neutrino interaction vertex. Subsequent reconstruction algorithms use this location to identify the individual primary particles and ensure they each result in a separate reconstructed particle. A new vertex-finding procedure described in this article integrates a U-ResNet neural network performing hit-level classification into the multi-algorithm approach used by Pandora to identify the neutrino interaction vertex. The machine learning solution is seamlessly integrated into a chain of pattern-recognition algorithms. The technique substantially outperforms the previous BDT-based solution, with a more than 20\% increase in the efficiency of sub-1\,cm vertex reconstruction across all neutrino flavours.

hep-ex↗

arXiv2024

The track-length extension fitting algorithm for energy measurement of interacting particles in liquid argon TPCs and its performance with ProtoDUNE-SP data

This paper introduces a novel track-length extension fitting algorithm for measuring the kinetic energies of inelastically interacting particles in liquid argon time projection chambers (LArTPCs). The algorithm finds the most probable offset in track length for a track-like object by comparing the measured ionization density as a function of position with a theoretical prediction of the energy loss as a function of the energy, including models of electron recombination and detector response. The algorithm can be used to measure the energies of particles that interact before they stop, such as charged pions that are absorbed by argon nuclei. The algorithm's energy measurement resolutions and fractional biases are presented as functions of particle kinetic energy and number of track hits using samples of stopping secondary charged pions in data collected by the ProtoDUNE-SP detector, and also in a detailed simulation. Additional studies describe the impact of the dE/dx model on energy measurement performance. The method described in this paper to characterize the energy measurement performance can be repeated in any LArTPC experiment using stopping secondary charged pions.

physics.ins-det↗

arXiv2024

In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits

The low temperature physics of structurally amorphous materials is governed by two-level system defects (TLS), the exact origin and nature of which remain elusive despite decades of study. Recent advances towards realising stable high-coherence platforms for quantum computing has increased the importance of studying TLS in solid-state quantum circuits, as they are a persistent source of decoherence and instability. Here we perform scanning gate microscopy on a live superconducting quantum circuit at millikelvin temperatures to locate individual TLS. Our method directly reveals the microscopic nature of TLS and is also capable of deducing the three dimensional orientation of individual TLS electric dipole moments. Such insights, when combined with structural information of the underlying materials, can help unravel the detailed microscopic nature and chemical origin of TLS, directing strategies for their eventual mitigation.

cond-mat.mtrl-sci↗

arXiv2024

DUNE Phase II: Scientific Opportunities, Detector Concepts, Technological Solutions

The international collaboration designing and constructing the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF) has developed a two-phase strategy toward the implementation of this leading-edge, large-scale science project. The 2023 report of the US Particle Physics Project Prioritization Panel (P5) reaffirmed this vision and strongly endorsed DUNE Phase I and Phase II, as did the European Strategy for Particle Physics. While the construction of the DUNE Phase I is well underway, this White Paper focuses on DUNE Phase II planning. DUNE Phase-II consists of a third and fourth far detector (FD) module, an upgraded near detector complex, and an enhanced 2.1 MW beam. The fourth FD module is conceived as a "Module of Opportunity", aimed at expanding the physics opportunities, in addition to supporting the core DUNE science program, with more advanced technologies. This document highlights the increased science opportunities offered by the DUNE Phase II near and far detectors, including long-baseline neutrino oscillation physics, neutrino astrophysics, and physics beyond the standard model. It describes the DUNE Phase II near and far detector technologies and detector design concepts that are currently under consideration. A summary of key R&D goals and prototyping phases needed to realize the Phase II detector technical designs is also provided. DUNE's Phase II detectors, along with the increased beam power, will complete the full scope of DUNE, enabling a multi-decadal program of groundbreaking science with neutrinos.

physics.ins-det↗

arXiv2024

First Measurement of the Total Inelastic Cross-Section of Positively-Charged Kaons on Argon at Energies Between 5.0 and 7.5 GeV

ProtoDUNE Single-Phase (ProtoDUNE-SP) is a 770-ton liquid argon time projection chamber that operated in a hadron test beam at the CERN Neutrino Platform in 2018. We present a measurement of the total inelastic cross section of charged kaons on argon as a function of kaon energy using 6 and 7 GeV/$c$ beam momentum settings. The flux-weighted average of the extracted inelastic cross section at each beam momentum setting was measured to be 380$\pm$26 mbarns for the 6 GeV/$c$ setting and 379$\pm$35 mbarns for the 7 GeV/$c$ setting.

hep-ex↗

arXiv2024

Supernova Pointing Capabilities of DUNE

The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on 40Ar and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called ``brems flipping'', as well as the burst direction from an ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE's burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage.

hep-ex↗

arXiv2024

Performance of a modular ton-scale pixel-readout liquid argon time projection chamber

The Module-0 Demonstrator is a single-phase 600 kg liquid argon time projection chamber operated as a prototype for the DUNE liquid argon near detector. Based on the ArgonCube design concept, Module-0 features a novel 80k-channel pixelated charge readout and advanced high-coverage photon detection system. In this paper, we present an analysis of an eight-day data set consisting of 25 million cosmic ray events collected in the spring of 2021. We use this sample to demonstrate the imaging performance of the charge and light readout systems as well as the signal correlations between the two. We also report argon purity and detector uniformity measurements, and provide comparisons to detector simulations.

physics.ins-det↗

arXiv2024

Doping Liquid Argon with Xenon in ProtoDUNE Single-Phase: Effects on Scintillation Light

Doping of liquid argon TPCs (LArTPCs) with a small concentration of xenon is a technique for light-shifting and facilitates the detection of the liquid argon scintillation light. In this paper, we present the results of the first doping test ever performed in a kiloton-scale LArTPC. From February to May 2020, we carried out this special run in the single-phase DUNE Far Detector prototype (ProtoDUNE-SP) at CERN, featuring 720 t of total liquid argon mass with 410 t of fiducial mass. A 5.4 ppm nitrogen contamination was present during the xenon doping campaign. The goal of the run was to measure the light and charge response of the detector to the addition of xenon, up to a concentration of 18.8 ppm. The main purpose was to test the possibility for reduction of non-uniformities in light collection, caused by deployment of photon detectors only within the anode planes. Light collection was analysed as a function of the xenon concentration, by using the pre-existing photon detection system (PDS) of ProtoDUNE-SP and an additional smaller set-up installed specifically for this run. In this paper we first summarize our current understanding of the argon-xenon energy transfer process and the impact of the presence of nitrogen in argon with and without xenon dopant. We then describe the key elements of ProtoDUNE-SP and the injection method deployed. Two dedicated photon detectors were able to collect the light produced by xenon and the total light. The ratio of these components was measured to be about 0.65 as 18.8 ppm of xenon were injected. We performed studies of the collection efficiency as a function of the distance between tracks and light detectors, demonstrating enhanced uniformity of response for the anode-mounted PDS. We also show that xenon doping can substantially recover light losses due to contamination of the liquid argon by nitrogen.

physics.ins-det↗

arXiv2024

Magnetic field amplification in massive primordial halos: Influence of Lyman-Werner radiation

The potential importance of magnetic fields during structure formation and gravitational collapse in the early Universe has been shown in several studies. In particular, magnetic field amplification by the small-scale dynamo plays an important role in addition to the pure amplification expected from gravitational collapse. In this paper, we study the small-scale dynamo for halos of $\gtrsim10^7$ M$_\odot$ collapsing at $z\gtrsim12$, under different ambient conditions due to the strength of the Lyman-Werner background. Additionally, we estimate the approximate saturation level by varying the initial magnetic field strength. We performed cosmological magnetohydrodynamical simulations for three distinct halos of $\sim10^7$ M$_{\odot}$ at $z\geq13$ by varying the Jeans resolution from $32-256$ cells and employed Lyman Werner background flux of strengths $10^2-10^5$ in units of $J_{21}$, where $J_{21}=10^{-21}$ erg$/$cm$^2/$sr$/$s$/$Hz. To follow the chemical and thermal evolution of the gas we made use of the KROME package. In addition to the compression by collapse, we find magnetic field amplification via the dynamo both in the regimes of atomic and molecular hydrogen cooling. Moreover, we find a lower saturation level in the molecular hydrogen cooling regime. This behaviour can be understood due to the generally reduced radial infall velocities and vorticities in this regime, as well as the higher Mach numbers of the gas, which give rise to a smaller saturation ratio. Our results overall suggest that the dynamo operates over a large range of conditions in the collapsing gas.

astro-ph.GA↗