Holonomy corrections, which are integral to loop quantum gravity (LQG), have recently been consistently incorporated for the classical Schwarzschild black hole using a novel framework that lets one incorporate non-perturbative quantum geometry corrections in a generally covariant manner. The vacuum spherically symmetric solutions, solved in different gauges, are shown to describe the same...
In this talk I will start by introducing the POWHEG method for matching fixed order calculations to a parton shower. I will show how the double counting is removed by POWHEG. Then I will go on to look at an extension to this which is resonance aware, POWHEG-RES. This extension to POWHEG adds the complexity of the matching algorithm keeping track of the productions channels associated with a...
Jet vetoes are important tools that are frequently used to cut away backgrounds or separate different hard scattering processes. Rapidity dependent jet vetoes with a tight veto at central rapidities and a loose veto at forward rapidities can reduce sensitivity to jets from pile-up and the underlying event. Applying tight cuts on such variables requires resummation of large logarithms of the...
I will discuss the subtle interplay between the behaviour of gravity as we observe it in our “everyday experiments”, and its embedding within an ultimate high energy completion. In particular, I will emphasize how the notion of causality is manifested with gravity, a consideration which is particularly relevant for putting constraints on the physical theories we use to describe observations...
Asymptotic Safety was proposed by Weinberg as a novel way to deal with quantum gravity. Einstein theory of gravity is in principle not renormalizable, however, one need not run the couplings to Planck scale if there is a non-trivial fixed point for the couplings. All the beta functions of the theory should vanish at this fixed point rendering signs for a conformal theory. Hence, the beta...
Davidson and Ibarra showed that for successful matter anti-matter asymmetry generation from extending the Standard Model to include Dirac and Majorana Neutrino mass contributions, the lightest Right Handed Neutrino (RHN) mass possible is $10^9$ GeV, known as the Davidson Ibarra (DI) bound. Falkowski et al introduced a new interaction to this standard Leptogenesis model resulting in two sector...
This work extends the Standard Model with a set of scalar electroweak multiplets that gain the majority of their mass via the Higgs mechanism. These particles are non-decoupling, providing a pattern of deviations to low energy observables that require a HEFT description. Considering their minimal gauge and Higgs couplings, I'll show that almost any additional scalar to the SM with these...
In this work, we present a detailed computation of the standard and constraint effective potentials in 4-dimensional de Sitter spacetime. Second to the pathologies arising in the perturbation theory of "lighter-than-Hubble" scalars, the stochastic approach is commonly used in the literature to describe the dynamics of scalar degrees of freedom. However, some ambiguities appear in the set-up of...
In this talk, I shall discuss the phenomenological prospects of neutral triple Higgs production compared to di-Higgs production across various Higgs-sector extensions (R2HDM, C2HDM and N2HDM), all within the context of a strong first-order electroweak phase transition. Our analysis reveals that scalar sector resonance contributions can significantly enhance triple Higgs production, despite the...
How do we extend the power of recursion relations to curved spacetimes? In this talk, I will present a novel framework for computing Feynman diagrams on arbitrary FLRW spacetimes, breaking them into lower-order diagrams through causality-driven recursion relations. This approach generalizes the celebrated BCFW recursion relations, traditionally confined to Minkowski spacetime, to settings...
We investigate the modular properties of Generalised Gibbs Ensembles (GGEs) in two dimensional conformal field theories. These are obtained by inserting higher spin charges in the expressions for the partition function of the theory. We investigate the particular case where KdV charges are inserted in the GGE. We first determine an asymptotic expression for the transformed GGE. This expression...
Entanglement entropy quantifies the degree of entanglement between two quantum systems or between two subregions in a QFT and hence is an important tool to understand the quantum system. However, its study in dimensions $> 2$ has been mostly limited to flat backgrounds and CFT vacuum states in specific subregions due to technical as well as conceptual difficulties. In this talk, I will present...
End-of-the-World branes are codimension-one hypersurfaces that mark the ending of spacetime. Interestingly, these have been argued to be necessary ingredients in quantum gravity to prevent the presence of global symmetries. Can they also serve as braneworlds? (Spoiler: Yes.) Motivated by the Swampland Programme and in particular the Cobordism Conjecture, we propose a scenario in which a...
We generalise Phinney's 'practical theorem' to account for modified graviton dispersion relations motivated by certain cosmological scenarios. Focusing on specific examples, we show how such modifications can induce characteristic localised distortions, bumps, in the frequency profile of the stochastic gravitational wave background emitted from distant binary sources. We concentrate on...
An open problem in theoretical physics is to combine all four of the fundamental forces of nature into one single theory. Problematically, gravity has proven difficult to reconcile with the other forces. Recently, relationships between scattering amplitudes (the quantity related to the probability for an interaction to occur between two or more particles) in non-abelian gauge theories (such as...
Abstract: The classical bulk reconstruction of Locally Asymptotically Anti-de Sitter (LAAdS) spacetimes and the associated computation of boundary correlators and a boundary stress-energy tensor constitute some of the first non-trivial checks of the AdS/CFT correspondence. I will begin this talk with a brief nod to this remarkable story, following which I will discuss setups that can be, and...
In this poster, I will present the LUX-ZEPLIN experiment and how its world-leading sensitivity is being used to search for a variety of dark matter candidates and other astrophysical signals, such as coherent elastic neutrino nuclear scattering from Boron 8 solar neutrinos. Having already set the best limit on WIMP cross section, $\sigma_{SI} = 2.2\times 10^{-48}$cm$^{2}$ at $43$ GeV/c$^{2}$,...
Inflation is a period of the very early universe proposed to explain, among other experimental observations, the fact that the Cosmic Microwave Background is incredibly isotropic. The characteristic energy scale of such a period may have been anywhere up to $10^{15}$ GeV, and therefore observables from this period can give us information about physics well beyond the reach of any conceivable...
Poster Abstract:
When using matrix methods in quantum mechanics it is common to use orthogonal polynomials as an expansion basis. The eigenvalues and eigenvectors of such provide the energies and wavefunctions for bound states in the Schrodinger equation, and when considering a complex scaling method we can extract the lifetimes of resonance states. Investigating the properties of orthogonal...
Decay constants parametrise non-perturbative strong interactions in leptonic weak decays of mesons. Here, we present new lattice QCD results for the vector-to-pseudoscalar and tensor-to-vector ratios of decay constants of the $B^{(*)}, B_s^{(*)}, D^{(*)}$ and $D_s^{(*)}$ mesons. Many correlated uncertainties cancel in these ratios, yielding high-precision results. We use the Highly Improved...
The 5.2$\sigma$ discrepancy between the 2020 theoretical evaluation of the muon anomalous magnetic moment $a_\mu$ and the most recent measurement made by the Fermilab muon $g-2$ collaboration has the potential to be one of the most significant results in modern particle physics. However, tensions between experimental inputs to the dispersive calculation of the hadronic vacuum polarisation...
We introduce an efficient method for deriving hierarchical constraints on the discontinuities of individual Feynman integrals. This method can be applied at any loop order and particle multiplicity, and to any configuration of massive or massless virtual particles. The resulting constraints hold to all orders in dimensional regularization, and complement the extended Steinmann relations --...
An open problem in theoretical physics is to combine all four of the fundamental forces of nature into one single theory. Problematically, gravity has proven difficult to reconcile with the other forces. Recently, relationships between scattering amplitudes (the quantity related to the probability for an interaction to occur between two or more particles) in non-abelian gauge theories (such as...
The growing array of precision measurements below the electroweak scale holds substantial significance for models of heavy new physics. To fully utilise these measurements, we must understand the running of the many operators of the Low Energy Effective Field Theory (LEFT aka WET). In this talk, I will introduce the LEFT and outline how decomposing operators according to their flavour and...
The discovery potential of the Standard Model Effective Field Theory (SMEFT) is expanded by studying dimension-8 operators and their impact on $W^+W^−$ production in gluon-gluon fusion at the Large Hadron Collider (LHC). This channel, which may contain large Beyond the Standard Model (BSM) contributions in the high-energy tail of its di-lepton mass distribution, presents unique challenges due...
One of the main questions in the classical double copy is its precise realisation around curved spacetime. One can make progress using a recent twistor formulation of the double copy. In the case of topologically massive theories in curved spacetime, it can give rise to the previously known double copy of waves. However the curved spacetime alters the straightforward "equal mass" prescription...
The observations of supernovae can place strong bounds on the couplings of particles beyond the standard model, with masses all the way up to ~200MeV. We study new scalar particles and show that for masses less than the plasma frequency in the supernova core, they are predominantly produced by resonant mixing with an emergent in-medium degree of freedom known as the longitudinal photon. Unlike...
Given a gauge Lie algebra, it is natural to seek representations for four-dimensional spacetime fermions that are anomaly-free and complex. Even for irreducible representations, where the problem reduces to studying $\mathfrak{su}_n$ for $n\geq3$, solutions seem to be few and far between: a trial-and-error scan by Eichten, Kang and Koh found only three for $\mathfrak{su}_5$, for example. In...
In this talk I shall talk about insertion of defects into a conformal field theory. Specifically, I shall discuss a setup with two conformal defects, and an effective field theory description of this setup, and the symmetries that this setup preserves. This is based on work with Petr Kravchuk and Ritam Sinha (arXiv:2406.04561).
Heavy neutral leptons (HNLs) are constrained by requirements of Big Bang Nu- cleosynthesis (BBN) as their decays significantly impact the formation of the primordial elements. We propose here a model where the primary decay channel for the HNLs is to an axion-like particle (ALP) and a neutrino. Consequently, HNLs can decay earlier and evade the BBN bound for lower masses, provided the ALPs...
The QCD axion, a favourable candidate for dark matter and a solution to the strong CP problem, can efficiently convert into photons in the presence of high magnetic fields. Neutron stars harbour high magnetic fields ($ \approx 10^{12}$ G) and serve as powerful probes to search for axion-photon conversion via observation of radio emission at the axion frequency $\hbar \omega = m_a c^2$, with...
Entanglement entropy quantifies the degree of entanglement between two quantum systems or between two subregions in a QFT and hence is an important tool to understand the quantum system. However, its study in dimensions $> 2$ has been mostly limited to flat backgrounds and CFT vacuum states in specific subregions due to technical as well as conceptual difficulties. In this talk, I will present...
There are a multitude of Standard Model extensions that can accommodate a first-order electroweak phase transition in the Early Universe, with the aim of providing an explanation for the observed baryon asymmetry. In this talk, I will introduce a particular extension: a Two Higgs Doublet Model plus a SM singlet pseudoscalar (2HDM+a). I will discuss how one starts from this model and ends with...
In the Kaluza-Klein theory with fuzzy sphere fiber, I will show how SU(2) Yang-Mills field and a real-symmetric-matrix valued Liouville-sigma model field arise from the dimensional reduction of Ricci scalar. Moreover, with this noncommutative fiber, we can derive the cylinder ansatz in usual KK theory.
Additionally, the KK tower of scalar and spinor field will obtain the natural truncation...
I will present a natural mechanism to achieve resonant leptogenesis through a novel approach involving thermal corrections to sterile neutrino masses. In standard leptogenesis, right-handed neutrinos are introduced as an extension to the Standard Model, generating a lepton asymmetry via CP-violating decays. This asymmetry is then converted into a baryon asymmetry through sphaleron processes....
End-of-the-World branes are codimension-one hypersurfaces that mark the ending of spacetime. Interestingly, these have been argued to be necessary ingredients in quantum gravity to prevent the presence of global symmetries. Can they also serve as braneworlds? (Spoiler: Yes.) Motivated by the Swampland Programme and in particular the Cobordism Conjecture, we propose a scenario in which a...
Abstract:
Understanding and detecting gravitational waves is key to testing new theories.
Gravitational wave calculations from black holes all assume the background spacetime is flat.
Understanding these in a de Sitter background is imperative, and has a two-fold effect:
- It expands the reach of future gravity waves observations to the earliest universe (inflation) and also the largest...
We introduce the Higgs mechanism for the self-dual spin connection (also known as the Ashtekar connection), using the Pleba\'{n}ski formulation of gravity. We develop our formalism within the framework of the chiral action and derive the equations of motion of the theory. One particular test model is explored: since anisotropy is an intrinsic property of the theory, a modified version of the...
We generalise Phinney's 'practical theorem' to account for modified graviton dispersion relations motivated by certain cosmological scenarios. Focusing on specific examples, we show how such modifications can induce characteristic localised distortions, bumps, in the frequency profile of the stochastic gravitational wave background emitted from distant binary sources. We concentrate on...
While understanding the consequences of quantising gravity remains an ongoing challenge, valuable insights have been gained by considering models in lower dimensions. In particular, I shall focus on Einstein gravity in 2+1d, which is known to be related to Chern-Simons theories, with a gauge group dependent on the sign of the cosmological constant. Unlike in 3+1d where gravitational waves are...
The possibility of detecting ultra-heavy dark matter often poses a significant challenge due to the incredibly suppressed flux. As a result, even models with high cross sections with respect to the weak scale WIMPs remain unconstrained. In this talk, we show the potential for future large scale acoustic detectors in the ocean initially proposed for ultra high energy neutrino detection could...
Multi-metric gravity is the umbrella term for a class of modified gravitational theories, motivated by a number of problems at the interface between gravity and particle physics, that extend general relativity (GR) via the inclusion of additional interacting massive spin-2 fields beyond the single massless graviton of GR. Nonlinearly, the extra interactions manifest as a framework where...
