A5061681290- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Black Holes and Theoretical Physics
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Atomic and Subatomic Physics Research
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Quantum, superfluid, helium dynamics
- Neutrino Physics Research
- Advanced Chemical Physics Studies
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Nuclear physics research studies
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Nuclear Physics and Applications
- Magnetic properties of thin films
- Scientific Research and Discoveries
- Magnetic Properties of Alloys
- Astrophysical Phenomena and Observations
- Noncommutative and Quantum Gravity Theories
King's College London
2016-2025
Fermi National Accelerator Laboratory
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Roma I
2024
University of Pisa
2024
Pacific Northwest National Laboratory
2024
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
2024
Augustana University
2024
King's College - North Carolina
2009-2024
Universidade de São Paulo
2024
Royal Holloway University of London
2024
This document a outlines set of simplified models for dark matter and its interactions with Standard Model particles. It is intended to summarize the main characteristics that these have when applied searches at LHC, provide number useful expressions reference. The list includes both s-channel t-channel scenarios. For s-channel, spin-0 spin-1 mediations are discussed, also realizations where Higgs particle provides portal between visible sectors. guiding principles underpinning proposed...
We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of spin-precession frequencies stored ultracold neutrons and 199Hg atoms an axion-induced oscillating electric dipole moment neutron axion-wind effect. No signal consistent with is observed axion mass range 10−24≤ma≤10−17 eV. Our null result sets first laboratory constraints coupling to gluons, which improve astrophysical limits up 3 orders magnitude, also improves previous nucleons factor 40.Received 29...
New light states thermally coupled to the Standard Model plasma alter expansion history of Universe and impact synthesis primordial elements. In this work, we carry out an exhaustive precise analysis implications MeV-scale BSM particles in Big Bang Nucleosynthesis (BBN) for Cosmic Microwave Background (CMB) observations. We find that BBN observations set a lower bound on thermal dark matter mass mχ > 0.4 MeV at 2σ. This is independent spin number internal degrees freedom particle,...
The most conservative interpretation of the nHz stochastic gravitational wave background (SGWB) discovered by NANOGrav and other pulsar timing array (PTA) collaborations is astrophysical, namely that it originates from supermassive black hole (SMBH) binaries. However, alternative cosmological models have been proposed, including cosmic strings, phase transitions, domain walls, primordial fluctuations, ``audible'' axions. We perform a multimodel analysis (MMA) to compare how well these...
Dark matter elastic scattering off nuclei can result in the excitation and ionization of recoiling atom through so-called Migdal effect. The energy deposition from electron adds to deposited by nuclear system allows for detection interactions sub-GeV/c^{2} mass dark matter. We present new constraints using dual-phase liquid argon time projection chamber DarkSide-50 experiment with an exposure (12 306±184) kg d. analysis is based on signal alone significantly enhances sensitivity DarkSide-50,...
The NANOGrav and other pulsar timing arrays (PTAs) have recently announced evidence for nHz gravitational waves (GWs) that may originate from supermassive black hole (SMBH) binaries. spectral index of the GW signal differs predicted binary evolution by emission alone, we show environmental effects such as dynamical friction with gas, stars, dark matter improve consistency SMBH model PTA data. We comment on possible implications observations fluctuations in frequency spectrum measurements GWs...
If dark matter is composed of axions, then axion stars form in the cores halos. These are unstable above a critical mass, decaying to radio photons that heat intergalactic medium, offering new channel for indirect detection. We recently provided first accurate calculation decay rate due star mergers. In this work we show how existing data concerning CMB optical depth leads strong constraints on photon coupling mass range <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
Solitons are observed to form in simulations of dark matter (DM) halos consisting bosonic fields. We use the extended Press-Schechter formalism compute mass function solitons, assuming various forms for relationship between halo and soliton mass. further provide a new calculation rate major mergers. composed axion DM unstable above critical mass, decay either relativistic axions or photons, depending on values coupling constants. computed merger predict enhanced due instability. For certain...
We discuss the consequences of accretion dark matter (DM) particles on compact stars such as white dwarfs and neutron stars. show that in large regions DM parameter space, these objects are sensitive probes presence can be used to set constraints both density physical properties particles.
We examine whether the accretion of dark matter onto neutron stars could ever have any visible external effects. Captured which subsequently annihilates will heat stars, although it seems effect be too small to close at an observable rate while those galactic center are obscured by dust. Nonannihilating would accumulate star. In a very dense region such as that may found galaxy, star might accrete enough cause collapse within period time less than age Universe. calculate what value stable...
High resolution cosmological N-body simulations of four galaxy-scale dark matter halos are compared to corresponding N-body/hydrodynamical containing matter, stars and gas. The without baryons share features with others described in the literature that density slope continuously decreases towards center, a \rho~r^{-1.3+/-0.2}, at about 1% virial radius for our Milky Way sized galaxies. central cusps which also contain steepen significantly, \rho~r^{-1.9+/-0.2}, an indication inner...
An attempt is made to fit the symmetries of currently observed elementary-particle spectrum into structure finite or disconnected subgroups SU3. Surprisingly, detailed properties these have not been elucidated previously. As a first step, therefore, character tables and other relevant are derived for groups. Next, classification elementary particles on basis representations groups discussed. The techniques previously employed by Case, Karplus, Yang application SU2 isotopic spin extended SU3...
We discuss the interpretation of annual modulation signal seen in DAMA experiment terms spin-independent elastic WIMP scattering. Taking into account channeling crystal as well spectral signature we find that low-mass region consistent with data is confined to masses close mχ ≃ 12 GeV, disagreement constraints from CDMS and XENON. conclude even if taken this disfavoured. There are no overlap regions parameter space at 90% CL a consistency test gives probability 1.2 × 10−5. study robustness...
The classical equations of motion for an axion with potential V(ϕ)=ma2fa2 [1−cos (ϕ/fa)] possess quasi-stable, localized, oscillating solutions, which we refer to as ``axion stars''. We study, the first time, collapse stars numerically using full non-linear Einstein general relativity and non-perturbative cosine potential. map regions on star stability diagram", parameterized by initial ADM mass, MADM, decay constant, fa. identify three parameter space: i) long-lived a base frequency, ma,...
If the symmetry breaking responsible for axion dark matter production occurs during radiation-dominated epoch in early Universe, then this produces large amplitude perturbations that collapse into dense objects known as miniclusters. The characteristic minicluster mass, $M_0$, is set by mass inside horizon when oscillations begin. For QCD $M_0\sim 10^{-10}M_\odot$, however an axion-like particle $M_0$ can approach $M_\odot$ or higher. Using Press-Schechter formalism we compute function of...
We consider the effect of a period inflation with high energy density upon stability Higgs potential in early universe. The recent measurement large tensor-to-scalar ratio, $r_T \sim 0.16$, by BICEP-2 experiment possibly implies that during was very high, comparable GUT scale. Given standard model is known to develop an instability at $\Lambda 10^{10}$ GeV this means resulting quantum fluctuations field could destabilize vacuum inflation, even if starts zero expectation value. estimate...
Based on the established task of identifying boosted, hadronically decaying top quarks, we compare a wide range modern machine learning approaches. Unlike most methods they rely low-level input, for instance calorimeter output. While their network architectures are vastly different, performance is comparatively similar. In general, find that these new approaches extremely powerful and great fun.
We explore the constraints imposed by cancellation of triangle anomalies on models in which flavour reported LHCb and other experiments are due to an extra U(1) $$^\prime $$ gauge boson Z . assume universal rational charges for first two generations left-handed quarks right-handed up-type but allow different their third-generation counterparts. If vanish, requires all quark if there either no exotic fermions or is only one Standard Model singlet dark matter (DM) fermion. There non-trivial...
A bstract We study the spectrum of gravitational waves produced by a first order phase transition in hidden sector that is colder than visible sector. In this scenario, bubbles vacuum can be nucleated through either thermal fluctuations or quantum tunnelling. If cold undergoes thermally induced transition, amplitude wave signal will suppressed and its peak frequency shifted compared to if temperatures were equal. This could lead signals range would otherwise ruled out constraints from big...
The next generation of dark matter direct detection experiments will be sensitive to both coherent neutrino-nucleus and neutrino-electron scattering. This enable them explore aspects solar physics, perform the lowest energy measurement weak angle sin2 θ W date, probe contributions from new theories with light mediators. In this article, we compute projected nuclear electron recoil rates expected in several due neutrinos, use these estimates quantify errors on future measurements neutrino...
NANOGrav and other Pulsar Timing Arrays (PTAs) have discovered a common-spectrum process in the nHz range that may be due to gravitational waves (GWs): if so, they are likely been generated by black hole (BH) binaries with total masses $> 10^9 M_{\odot}$. Using Extended Press-Schechter formalism model galactic halo mass function simple relation between BH suggests these redshifts $z = {O}(1)$ ratios $\gtrsim 10$, GW signal at frequencies above ${O}(10)$~nHz dominated relatively few could...