A5065634162- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Black Holes and Theoretical Physics
- Distributed and Parallel Computing Systems
- Computational Physics and Python Applications
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Atomic and Subatomic Physics Research
- Scientific Computing and Data Management
- Superconducting and THz Device Technology
- Pulsars and Gravitational Waves Research
- Quantum Mechanics and Applications
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Laser-Plasma Interactions and Diagnostics
- Seismic Waves and Analysis
- Cellular Automata and Applications
- Biomedical and Engineering Education
- Medical Imaging Techniques and Applications
- Neural Networks and Applications
- International Science and Diplomacy
King's College London
2012-2024
University of Cambridge
2016-2023
European Organization for Nuclear Research
2012-2023
Bridge University
2018
Imperial College London
2012
The discovery of the Higgs boson in 2012, by ATLAS and CMS experiments, was a success achieved with only percent entire dataset foreseen for LHC. It opened landscape possibilities study properties, Electroweak Symmetry breaking Standard Model general, as well new avenues probing physics beyond Model. Six years after discovery, conspicuously larger collected during LHC Run 2 at 13 TeV centre-of-mass energy, theory experimental particle communities have started meticulous exploration potential...
A bstract The search for effective field theory deformations of the Standard Model (SM) is a major goal particle physics that can benefit from global approach in framework Effective Field Theory (SMEFT). For first time, we include LHC data on top production and differential distributions together with Higgs decay rates Simplified Template Cross-Section (STXS) measurements fit, as well precision electroweak diboson LEP LHC, analysis SMEFT operators dimension 6 included linearly. We present...
Constraints on the full set of Standard Model dimension-6 operators have previously used triple-gauge couplings to complement constraints obtainable from Higgs signal strengths. Here we extend previous analyses sector by including information associated production and massive vector bosons (H+V production), which excludes a direction limited sensitivity allowed partial cancellations in measured at LEP. Kinematic distributions H+V provide improved operators, as illustrate here with...
We treat the Standard Model as low-energy limit of an effective field theory that incorporates higher-dimensional operators to capture effects decoupled new physics. consider constraints imposed on coefficients dimension-6 by electroweak precision tests (EWPTs), applying a framework for dimension- 6 is more general than standard S, T formalism, and use measurements Higgs couplings kinematics associated production at Tevatron LHC, well triple-gauge LHC. highlight complementarity between...
A bstract There are many indirect and direct experimental indications that the new particle H discovered by ATLAS CMS Collaborations has spin zero (mostly) positive parity, its couplings to other particles correlated with their masses. To a high degree of confidence, it is Higgs boson, here we examine extent which resemble those single boson Standard Model. Our global analysis fermions massive bosons determines they have same relative sign as in We also show directly these highly consistent...
We consider interpretations of the recent ∼ 3σ reports by CMS and ATLAS collaborations a possible X (∼750 GeV) state decaying into γγ final states. focus on possibilities that this is scalar or pseudoscalar electroweak isoscalar produced gluon-gluon fusion mediated loops heavy fermions. several models for these fermions, including single vector-like charge 2/3 T quark, doublet quarks (T, B), generation quarks, with without leptons also contribute to → decay amplitude. possibility (750) dark...
The recent measurement by ATLAS of light-by-light scattering in LHC Pb-Pb collisions is the first direct evidence for this basic process. We find that it excludes a range mass scale nonlinear Born-Infeld extension QED ≲100 GeV, much stronger constraint than those derived previously. In case standard model which U(1)_{Y} hypercharge gauge symmetry realized nonlinearly, limit on corresponding reach ∼90 which, turn, imposes lower ≳11 TeV magnetic monopole such theory.
A bstract We analyze the properties of Higgs candidate with mass ~ 125 GeV discovered by CMS and ATLAS Collaborations, constraining possible deviations its couplings from those a Standard Model boson. The CMS, Tevatron data are compatible to massive gauge bosons fermions, disfavour several types composite models unless their resemble in Model. show that consistent linear dependence on particle masses, scaled electroweak scale v 246 GeV, power law both having uncertainties 20%.
The Universal One-Loop Effective Action (UOLEA) is a general expression for the effective action obtained by evaluating in model-independent way one-loop expansion of functional path integral. It can be used to match UV theories their low-energy EFTs more efficiently avoiding redundant steps application methods, simplifying process obtaining Wilson coefficients operators up dimension six. In addition loops involving only heavy fields, matching may require inclusion containing both and light...
We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied loops heavy fermions or bosons, and has been checked against partial results available in literature. The broad applicability this approach simplifies matching from an ultraviolet model a lower-energy field theory (EFT), procedure which is now reduced evaluation combination matrices our expression,...
Recently, a general result for evaluating the path integral at one loop was obtained in form of Universal One-Loop Effective Action. It may be used to derive effective field theory operators dimensions up six, by traces matrices this expression, with mass dependence encapsulated universal coefficients. Here we show that it can account loops mixed heavy–light particles matching procedure. Our prescription computing these contributions Wilson coefficients is conceptually simple. Moreover has...
A bstract We derive new effective field theory (EFT) positivity bounds on the elastic 2 → scattering amplitudes of massive spinning particles from standard UV properties unitarity, causality, locality and Lorentz invariance. By bounding t derivatives amplitude (which can be represented as angular momentum matrix elements) in terms total ingoing helicity, we stronger unitarity s - u -channel branch cuts which determine dispersion relation. In contrast to previous bounds, relate -derivative...
We use the Fitmaker tool to incorporate recent CDF measurement of $m_W$ in a global fit electroweak, Higgs, and diboson data Standard Model Effective Field Theory (SMEFT) including dimension-6 operators at linear order. find that any one SMEFT ${\cal O}_{HWB}$, O}_{HD}$, O}_{\ell \ell}$ or O}_{H \ell}^{(3)}$ with non-zero coefficient could provide better than Model, strongest pull for O}_{HD}$ no tension other electroweak precision data. then analyse which tree-level single-field extensions...
A bstract We perform a global analysis of the constraints on possible Higgs-like particle with mass ∼ 125 GeV that are provided by ATLAS, CDF, CMS and D0 experiments. combine available deviations from Standard Model Higgs couplings to massive vector bosons fermions, considering also possibilities non-standard loop-induced photon gluon pairs. analyze combined pseudo-dilaton scenarios some other in which new is identified as pseudo-Nambu-Goldstone boson composite electroweak symmetry-breaking sector.
In a recent paper, Cho, Kim and Yoon (CKY) have proposed version of the SU(2) $\times$ U(1) Standard Model with finite-energy monopole dyon solutions. The CKY model postulates that effective gauge coupling $\to \infty$ very rapidly as Englert-Brout-Higgs vacuum expectation value 0$, but in way is incompatible LHC measurements Higgs boson $H \to \gamma \gamma$ decay rate. We construct generalizations are compatible constraint, calculate corresponding values masses. find mass could be $< 5.5$...
Direct detection experiments relying on nuclear recoil signatures lose sensitivity to sub-GeV dark matter for typical galactic velocities. This is recovered if there exists another source of flux with higher momenta. Such an energetic light could originate from the decay mesons produced in inelastic cosmic ray collisions. We compute this novel production mechanism-a beam dump experiment-and estimate resulting limits XENON1T and LZ. find that rays colliding atmospheric nuclei can dominate...
We describe a new phenomenon in quantum cosmology: self-organised localisation. When the fundamental parameters of theory are functions scalar field subject to large fluctuations during inflation, phase transitions can act as dynamical attractors. As result, probabilistically localised around critical value and Universe finds itself at edge transition. illustrate how localisation could account for observed near-criticality Higgs self-coupling, naturalness mass, or smallness cosmological constant.
We point out that an unnatural hierarchy between certain higher-dimensional operator coefficients in a low-energy effective field theory (EFT) would automatically imply the Higgs’ vacuum expectation value is hierarchically smaller than EFT cutoff, assuming emerged from unitary, causal and local UV completion. Future colliders may have sensitivity to infer such pattern of for little with cutoff up <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi...
The LHC experiments ATLAS and CMS have discovered a new boson that resembles the long-sought Higgs boson: it cannot spin one, has couplings to other particles increase with their masses, but parity remain be determined. We show here `Higgs' + gauge invariant-mass distribution in `Higgs'-strahlung events at Tevatron or would very different under J^P = 0+, 0- 2+ hypotheses, could provide fast-track indicator of parity. Our analysis is based on simulations experimental event selections cuts...
We study the sensitivity of possible CLIC and FCC-ee measurements light-by-light scattering to old new physics, including Heisenberg-Euler Lagrangian in Standard Model with contributions from loops additional charged particles or magnetic monopoles, Born-Infeld extension QED, effective dimension-8 operators involving four electromagnetic field strengths as could appear Effective Field Theory. find that at 365 GeV 350 would be sensitive physics scales half a TeV operator coefficients, 1.4 3...
A bstract Axions and dark photons are common in many extensions of the Standard Model. The axion portal — an coupling to photon can significantly modify their phenomenology. We study cosmological constraints on from Cosmic Microwave Background (CMB) bounds energy density radiation, ∆ N eff . By computing axion-photon-dark collision terms solving Boltzmann equations including effects, we find that light axions generally more constrained by than supernova cooling or collider experiments....
We develop a universal approach to the one-loop effective field theory (EFT) using Covariant Derivative Expansion (CDE) method. generalise previous results include broader classes of UV models, showing how expressions previously obtained assuming degenerate heavy-particle masses can be extended non-degenerate cases. apply our method general MSSM with stop squarks, illustrating calculations coefficients dimension-6 operators contributing hgg and hγγ couplings, comparing exact Feynman...
We estimate the possible accuracies of measurements at proposed CLIC e + − collider Higgs and W production centre-of-mass energies up to 3 TeV, incorporating also Higgsstrahlung projections higher that had not been consid-ered previously, use them explore prospective sensitivities decoupled new physics. present resulting constraints on Wilson coefficients dimension-6 operators in a model-independent approach based Standard Model effective field theory (SM EFT). The energy CLIC, compared...
Pairs of Standard Model fermions form dimension-3 singlet operators that can couple to new dark sector states. This "fermion portal" is be contrasted with the lower-dimensional Higgs, vector and neutrino portals. We characterise its distinct phenomenology place effective field theory bounds on this framework, focusing case fermion portals a pair light fermions. obtain current projected limits dimension-6 operator scale from variety meson decay experiments, missing energy long-lived particle...