Stellar microlensing strongly constrains the fraction of dark matter in compact objects, such as primordial black holes (PBHs). However, PBHs are expected to form clusters, and it has been argued that these constraints are therefore weakened or evaded. I will present a plausible PBH cluster model for the most commonly-studied PBH formation mechanism: the collapse of large curvature...
In the past decade, the CHY formalism and positive geometries have arisen as interesting new ways to think about scattering amplitudes in certain theories. The former allows for scattering amplitudes to be calculated by summing over the solutions to a set of rational equations (the scattering equations), whereas the latter allows for scattering amplitudes to be calculated as the...
The ability to represent perturbative expansions of interacting quantum field theories in terms of simple diagrammatic rules has revolutionised calculations in particle physics. However, in the case of extended theories of gravity, deriving this set of rules requires linearization of gravity, perturbation of the scalar fields and multiple field redefinitions, making this process very...
The $\beta$-decay of tritium is the most promising approach to measure the absolute masses of active light neutrinos in the laboratory and in a model-independent fashion. The development of Cyclotron Radiation Emission Spectroscopy techniques and the use of atomic tritium has the potential to improve the current limits by an order of magnitude in future tritium experiments. In this paper, we...
Heavy Neutral Leptons (HNLs) are a popular extension of the Standard Model to explain the lightness of neutrino masses and the matter-antimatter asymmetry through leptogenesis. Future direct searches, such as fixed target setups like DUNE, and neutrinoless double beta decay are both expected to probe the regime of active-sterile neutrino mixing in a standard Seesaw scenario of neutrino mass...
In cosmology we measure correlation functions (cosmological correlators) which we can trace back to the boundary at the end of inflation. In the spirit of the S-matrix in flat space and holography in AdS, the cosmological bootstrap allows us to compute these boundary observables by sidestepping cumbersome Lagrangians, and instead using dS isometries and fundamental principles with no explicit...
We examine the phase plane of perturbative QCD involving a coupling constant and gauge parameter.We explore the fixed points in different schemes and with different gauge fixing terms in order to investigate the physical structure of the theory through recourse to scheme and gauge independence. Particularly the quark mass anomalous dimension and critical slope are considered at both the...
Quasinormal modes are the gravitational wave analogue to the overtones heard after striking a bell. They dominate the signal observed during the ringdown phase after a dynamical event and are characterised by complex frequencies, which encode oscillation and exponential decay in time. As horizons become extremal, various computations (both analytic and numerical) have shown that in many cases,...
The antenna subtraction method has been successfully applied to a wide range
of next-to-next-to-leading order in $\alpha_s$ (NNLO) processes relevant for the Large Hadron Collider. We summarise how the antenna subtraction method works at NLO and NNLO and identify the current drawbacks in the scheme. In particular, the tree-level four-particle antennae, $X_4^0$, extracted from known...
We study the problem of plane monochromatic scalar waves impinging upon a Schwarzschild dirty black hole and show that dirty black hole spacetimes may exhibit various critical effects for geometrical optics. We provide the complex angular momentum representation of the differential scattering cross section and examine the role of the different Regge pole branches. The role of the critical...
We study the C-metric in 2+1 dimensions ab initio. We find three classes of geometry, which we interpret by studying holographically their physical parameters. From these, we construct stationary, accelerating point particles; one-parameter extensions of the BTZ family resembling an accelerating black hole; and find new solutions including a novel accelerating “BTZ geometry” not continuously...
Phase transitions in gauge theories carry important information about the non-perturbative underlying dynamics. For instance, first-order phase transitions in the early universe generate a primordial gravitational wave background whose intensity can in principle be determined with lattice simulations. However, metastable dynamics at first order phase transitions make precise determination of...
In recent years there has been an increasing interest in the interplay between amplitudes and cosmological correlators, in particular in the use of amplitudes techniques to constrain cosmological correlators. In this talk, I will give an overview of the formalism of the wavefunction of the universe and how it relates to cosmological correlators. After this, I will review the success of the...
The study of supersymmetric and conformal field theories in diverse dimensions and classification of Type II or M-theory backgrounds with $\text{AdS}_{d+1}$ factors as their holographic duals in d dimensions is of substantial interest. In this talk, we focus on the case of conformal and supersymmetric linear quiver field theories in three and five dimensions preserving eight Poincare...
In this talk I will present the toolbox used in Pure Spinor Super Yang-Mills in 10 dimensions. The Pure Spinor formalism greatly simplifies the computation of string scattering amplitudes and by extension, the calculation of amplitudes in the SYM theory. In the talk I will briefly introduce the fundamentals of Pure Spinor superstring theory and its related BRST operator, which is fundamental...
On large scales, the dark matter distribution can be treated as a perfect fluid. On small scales, gravitationally bound structures form through nonlinear clustering. Capturing the resulting cascade of multiple fluid streams in 6d phase space is challenging. We approximate the time evolution of this complex phase-space dynamics using a wavefunction, in the spirit of the quantum-classical...
It has recently been argued by Gaberdiel, Gopakumar et al. that type IIB string theory on $AdS_3 \times S^3 \times \mathbb{T}^4$ in the tensionless limit is exactly dual to the symmetric orbifold CFT $\text{Sym}^N(\mathbb{T}^4)$ in the large $N$ limit. One fascinating feature of this duality is that it is rendered manifest by a localisation of the physical correlators of tensionless strings to...
Full non-linear simulations of massless preheating model have revealed a large non-Gaussianity can be generated. We study a more observationally viable model consisting of inflaton non-minimally coupled to gravity that decays into a massless scalar spectator during preheating.
Including the scale-dependence of Hubble rate places tight constraints on the 'cosmic variance', the values which...
In order to further study the coupling of the Higgs boson to vector bosons at the LHC, experimentalists use Vector Boson Fusion (VBF) cuts of large invariant mass between jets to isolate the relevant production mode. While this is efficient in suppressing the QCD background, it has the drawback of enhancing high-energy large logarithms effects to all orders in the strong coupling which must be...
I will discuss the information recovery problem for an object thrown into a black hole in JT gravity using the quantum extremal surface prescription. In particular, I will show how to reproduce the Hayden-Preskill decoding criterion but with some refinements, which include the effect of the backreaction of the infalling object.
In the Canonical theory of Quantum Gravity (CQG), states are given by the superposition of geometries on a Cauchy slice, called the Wheeler-DeWitt (WDW) states. On the other hand, the Holographic principle states that quantum gravity in d+1 spacetime dimensions is the same as a quantum field theory in d spacetime dimensions. In this talk, I will briefly review both of these and will explain...
The discrepancy between the Baryon Asymmetry of the Universe and its Standard Model (SM) prediction implies the existence of physics beyond the SM, which must include further sources of CP violation. Generically, physics beyond the SM comes with O(1) weak phases. LHCb has recently made several CP asymmetry measurements for B->DD decays. For such non-leptonic modes, a lack of knowledge of...
The $B_3-L_2$ $Z^\prime$ model may explain some gross features of the fermion mass spectrum as well as $b\rightarrow s \ell \ell$ anomalies. A TeV-scale physical scalar field associated with gauged $U(1)_{B_3-L_2}$ spontaneous symmetry breaking, the flavon field $\vartheta$, affects Higgs phenomenology via mixing. In this talk, I will discuss the collider phenomenology of the flavon field....
We present an algebra of generators of symmetry for massless higher-spin particles in asymptotically Minkowski space with dimension D ≥ 3, and show that it admits an extension to an algebra of asymptotic symmetries, similar to the generalized BMS algebra. We discuss its relevance for the asymptotic symmetries of Fronsdal fields and its implications for flat holography
The ghost-free massive gravity theory of de Rham, Gabadadze and Tolley (dRGT) has attracted a lot of attention since its formulation over a decade ago. Many studies have looked at its consequences for cosmology, and explored various limits in which the theory simplifies. However, until now few attempts have been made at numerically simulating its full non-linear equations, as an explicit...
We present the Axion-Higgs portal, the unique dimension six operator that respects both a Z2 symmetry and the typical shift symmetry of an axion. Due to the Z2 symmetry, the axion is stable for all masses and serves as a natural DM candidate. We derive experimental constraints and the regions where the observed amount of DM can be produced and compare them in the parameter space. Throughout...
By applying a comprehensive set of flavour observables, Higgs measurements, BSM searches, electroweak precision measurements and theoretical considerations, we are able to place the tightest constraints yet on the allowed parameter space of the Two Higgs Doublet Model, examining all four main types. Based on work from 2107.05650, 2202.08807, 2207.02789.
The double copy relates scattering amplitudes in quantum gravity as the square for those in non-abelian gauge theories. This property has been extended to relate position space solutions in classical physics in biadjoint scalar, gauge and gravity theories. So far, no strongly coupled examples of the double copy in four dimensions have been found, and previous attempts based on exact non-linear...
The DGLAP equations describe how parton distribution functions evolve between different energy scales. In this talk, we will discuss how potential effects of new physics, parametrised in terms of higher dimensional operators in the Standard Model Effective Field Theory, could affect these equations. We assess the importance of the dimensionality of the operators and the role that it plays in...
