A5005538023- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Diamond and Carbon-based Materials Research
- Atomic and Subatomic Physics Research
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Animal Diversity and Health Studies
- Force Microscopy Techniques and Applications
- Electronic and Structural Properties of Oxides
- Mechanical and Optical Resonators
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Black Holes and Theoretical Physics
- Advanced Semiconductor Detectors and Materials
- Particle physics theoretical and experimental studies
- High-pressure geophysics and materials
- Reproductive Physiology in Livestock
- Photonic and Optical Devices
- Complex Systems and Time Series Analysis
- Relativity and Gravitational Theory
- Terahertz technology and applications
- Metallurgy and Cultural Artifacts
- Milk Quality and Mastitis in Dairy Cows
- Integrated Circuits and Semiconductor Failure Analysis
University of Maryland, College Park
2021-2025
Mohammed Bin Rashid School of Government
2023-2025
Institute for Research in Fundamental Sciences
2020
Sharif University of Technology
2020
We present a novel mechanism for gravitational wave generation in the early Universe. Light spectator scalar fields during inflation can acquire blue-tilted power spectrum due to stochastic effects. show that this effect lead large curvature perturbations at small scales (induced by field fluctuations) while maintaining observed, slightly red-tilted cosmological inflaton fluctuations). Along with other observational signatures, such as enhanced dark matter substructure, induce background...
We outline the unique opportunities and challenges in search for “ultraheavy” dark matter candidates with masses between roughly 10 TeV Planck scale m_{\rm pl} ≈ 10^{16} TeV. This mass range presents a wide relatively unexplored parameter space, rich space of possible models cosmic histories. emphasize that both current detectors new, targeted techniques, via direct indirect detection, are poised to contribute searches ultraheavy particle coming decade. highlight need new developments this...
Abstract Features in the inflationary landscape can inject extra energies to inflation models and produce on-shell particles with masses much larger than Hubble scale of inflation. This possibility extends energy reach program cosmological collider physics, which signals associated these are generically Boltzmann-suppressed. We study mechanisms this classical two categories primordial features. In first category, feature is oscillation, includes case coherent oscillation a massive field...
Crystal-strain variation imposes significant limitations on many quantum sensing and information applications for solid-state defect qubits in diamond. Thus, the precision measurement control of diamond crystal strain is a key challenge. Here, we report measurements with unique set capabilities, including micron-scale spatial resolution, millimeter-scale field view, 2-order-of-magnitude improvement volume-normalized sensitivity over previous work, reaching...
Abstract We construct explicit models of classical primordial standard clocks in an alternative to inflation, namely the slowly contracting ekpyrotic scenario. study phenomenology massive spectator fields added a state-of-the-art model, with coupling functions that allow for these heavy be classically excited while background is contracting. perform numerical computations corrections scalar power spectrum and compare analytical estimates. Our full results reveal so-called clock signals,...
The temporal stability of millisecond pulsars is remarkable, rivaling even some terrestrial atomic clocks at long timescales. Using this property, we show that distributed in the galactic neighborhood form an ensemble accelerometers from which can directly extract local acceleration. From pulsar spin period measurements, demonstrate acceleration sensitivity with about $1\ensuremath{\sigma}$ precision using 117 pulsars. We also present a complementary analysis orbital periods 13 binary...
Self-interactions within the dark sector could clump matter into heavy composite states with low number density, leading to a highly suppressed event rate in existing direct detection experiments. However, large interaction cross section between such ultraheavy (UHDM) and standard model results distinctive compelling signature; long, straight damage tracks as they pass through scatter matter. In this work, we propose using geologically old quartz samples large-exposure detectors for UHDM. We...
Next-generation dark matter (DM) detectors searching for weakly interacting massive particles (WIMPs) will be sensitive to coherent scattering from solar neutrinos, demanding an efficient background-signal discrimination tool. Directional improve sensitivity WIMP DM despite the irreducible neutrino background. Wide-bandgap semiconductors offer a path directional detection in high-density target material. A detector of this type operates hybrid mode. The or neutrino-induced nuclear recoil is...
Recent studies reveal that more than a dozen of white dwarfs displaying near-perfect blackbody spectra in the optical range have been lurking Sloan Digital Sky Survey catalog. We point out that, way analogous to cosmic microwave background, these stars serve as excellent test beds for new physics. Specifically, we show how their observed lack spectral distortions translates into limits on parameter space axions with electromagnetic coupling. The prospects future improvements are also discussed.
The objectives of this study were to comparatively identify the common bacterial isolates from uteri camels coming different reproductive backgrounds after standardizing sampling method and investigate association clinically measurable parameters with uterine colonization by these isolates. samples 856 dromedary yielded a total 17 species higher proportion sub-fertile camel being colonized bacteria (66.6%) as compared nulliparous, recently calved, those unknown history combined (44.2%; p <...
We outline the unique opportunities and challenges in search for "ultraheavy" dark matter candidates with masses between roughly $10~{\rm TeV}$ Planck scale $m_{\rm pl} \approx 10^{16}~{\rm TeV}$. This mass range presents a wide relatively unexplored parameter space, rich space of possible models cosmic histories. emphasize that both current detectors new, targeted techniques, via direct indirect detection, are poised to contribute searches ultraheavy particle coming decade. highlight need...
We present a novel mechanism for gravitational wave generation in the early Universe. Light spectator scalar fields during inflation can acquire blue-tilted power spectrum due to stochastic effects. show that this effect lead large curvature perturbations at small scales (induced by field fluctuations) while maintaining observed, slightly red-tilted cosmological inflaton fluctuations). Along with other observational signatures, such as enhanced dark matter substructure, induce background...
We propose a novel experimental method for probing light dark matter candidates. show that an electro-optical material’s refractive index is modified in the presence of coherently oscillating background. A high-precision resonant Michelson interferometer can be used to read out this signal. The proposed detection scheme allows exploration uncharted parameter space candidates over wide range masses—including masses exceeding few tens microelectronvolts, which challenging microwave cavity...
We construct explicit models of classical primordial standard clocks in an alternative to inflation, namely the slowly contracting ekpyrotic scenario. study phenomenology massive spectator fields added a state-of-the-art model, with coupling functions that allow for these heavy be classically excited while background is contracting. perform numerical computations corrections scalar power spectrum and compare analytical estimates. Our full results reveal so-called clock signals, sharp feature...
Galactic double white dwarf (DWD) binaries are among the guaranteed sources for Laser Interferometer Space Antenna (LISA), an upcoming space-based gravitational wave (GW) detector. Most DWDs in LISA band far from merging and emit quasimonochromatic GWs. As these distributed throughout Milky Way, they experience different accelerations potential, therefore each DWD exhibits apparent GW frequency chirp due to differential acceleration between source LISA. We examine how influences parameter...
The nitrogen-vacancy (NV) center in diamond is an increasingly popular quantum sensor for microscopy of electrical current, magnetization, and spins. However, efficient NV–sample integration with a robust, high-quality interface remains outstanding challenge to realize scalable, high-throughput microscopy. In this work, we characterize micro-chip (DMC) containing (111)-oriented NV ensemble demonstrate its utility high-resolution We perform strain imaging the DMC find minimal detrimental...
The nitrogen vacancy (NV) center in diamond is an increasingly popular quantum sensor for microscopy of electrical current, magnetization, and spins. However, efficient NV-sample integration with a robust, high-quality interface remains outstanding challenge to realize scalable, high-throughput microscopy. In this work, we characterize micro-chip (DMC) containing (111)-oriented NV ensemble; demonstrate its utility high-resolution We perform strain imaging the DMC find minimal detrimental...
Minerals are solid state nuclear track detectors - recoils in a mineral leave latent damage to the crystal structure. Depending on and its temperature, features retained material from minutes (in low-melting point materials such as salts at few hundred degrees C) timescales much larger than 4.5 Gyr-age of Solar System refractory room temperature). The $O(50)$ MeV fission fragments left by spontaneous $^{238}$U other heavy unstable isotopes have long been used for dating geological samples....
Recent studies reveal that more than a dozen of white dwarfs displaying near-perfect blackbody spectra in the optical range have been lurking Sloan Digital Sky Survey catalog. We point out that, way analogous to Cosmic Microwave Background, these stars serve as excellent testbeds for new physics. Specifically, we show how their observed lack spectral distortions translates into limits on parameter space axions with electromagnetic coupling. The prospects future improvements are also discussed.
We propose a novel experimental method for probing light dark matter candidates. show that an electro-optical material's refractive index is modified in the presence of coherently oscillating background. A high-precision resonant Michelson interferometer can be used to read out this signal. The proposed detection scheme allows exploration uncharted parameter space candidates over wide range masses -- including exceeding few tens microelectronvolts, which challenging microwave cavity haloscopes.