I will provide a critical overview of the state-of-the-art in particle physics. I will then introduce new Wilsonian theories of fundamental interactions that have recently been put forward that are able to address old paradigms and that offer novel avenues for (astro) particle physics and cosmology.
Critical point of nuclear matter and beam energy dependence of net proton number fluctuations
I will discuss recent developments in theory of heavy ion physics. In particular, I will discuss how relativistic fluid dynamics arises from fundamental interactions and how the emergence of collective phenomena can be studied by focusing in questions where the hydrodynamical paradigm is under stress.
Heavy ion physics - experimental results
After the discovery of the Standard Model Higgs boson in 2012, we have entered the era of precision measurements of this particle. The decay to two W bosons constitutes the second largest branching ratio for the decay of the Higgs. An overview of the analysis strategy in the Higgs boson cross section measurement in the H->WW(*)->evμv decay channel performed by the ATLAS experiment will be...
The Quark Gluon Plasma (QGP) produced in the Large Hadron Collider (LHC) undergoes a similar evolution to that of our Universe. The collision produces an explosive expansion caused by high pressure gradients and it then cools down, forming free-streaming hadrons. The earliest stages of the Universe are probed through the cosmic microwave background (CMB). In a similar manner to the analysis...
Two-particle angular correlations as a function of pseudorapidity difference, $\Delta\eta$, and azimuthal angle difference, $\Delta\varphi$, are a comprehensive tool which allows the explaration of the underlying physics phenomena of particle production in collisions of both protons and heavy ions. These correlations open up the possibility to study a number of mechanisms simultaneously. Many...
We study the influence of geometric and dynamical anisotropies on the development of flow harmonics and, simultaneously, on the second- and third-order oscillations of femtoscopy radii. The analysis is done within the Monte Carlo event generator HYDJET++, which was extended to dynamical triangular deformations. It is shown that the merely geometric anisotropy provides the results which...
Study of the charmonium states play important role in understanding of the strong interaction. The most interesting charmonium states lie near or above open charm threshold. Nature of such states is of interest to modern physics. Recent lattice calculations have performed the necessary extrapolations and considered spectra as well as certain radiative transitions. The lattice QCD simulations...
In 1916 Albert Einstein showed that gravitational waves were a natural consequence of his theory of general relativity (GR) . Nothing much was done about this feature of GR until the 1950s since it was deemed to be either an unphysical mathematical oddity or simply too unfathomably small to ever be useful. In fact, if they were to ever be detected then the only things in the universe that...
Dark matter - theoretical overview
I will introduce the recently released software package the Global and Modular BSM Inference Tool (GAMBIT), focusing on the core features of GAMBIT and highlighting its collider physics module, ColliderBit. I will also briefly discuss some ongoing work within the GAMBIT collaboration, both in terms of software extensions and physics analyses.
The present landscape and the open questions in particle physics will be briefly reviewed, showing that they call for new means of investigation both towards higher energy and towards more sensitivity to small couplings.
CERN is preparing actively, according to the recommendation of the 2013 European Strategy, for an ambitious post-LHC accelerator complex. The 100km circumference Future...
Searching for a difference between neutrino and anti-neutrino oscillations may open the way towards new fundamental physics and an explanation of why the world is made of only matter and no anti-matter. To discover such a difference, the development of a very large neutrino detector and a high-intensity neutrino beam is needed. The same detector will make possible investigations of...
I will present the first Beyond the Standard Model (BSM) global fit results obtained using the new Global And Modular BSM Inference Tool (GAMBIT). With GAMBIT we have analysed the GUT-motivated supersymmetry models CMSSM, NUHM1 and NUHM2; the weak-scale MSSM7; and a scalar singlet dark matter model. Our analyses improve on existing results in terms of the number of included observables and the...
We study the prospects for using deep neural networks to distinguish collider signals from heavy and mass degenerate CP-odd and CP-even Higgs bosons. The close overlap in the kinematic features highlights a challenge related to the bias introduced by training data.
In order to improve track reconstruction in Run 2 and to prepare for the increasingly difficult detector conditions of Run 3 at the Compact Muon Solenoid (CMS) detector, the use of novel machine learning methods in the CMS tracking are being studied. These methods provide ways to deal with for example the high particle densities, growing combinatorics and track quality assignments in the...
In this Masters thesis we have developed a faster way to calculate
supersymmetric cross sections at next-to-leading order (NLO) by using
machine learning techniques. This method teaches the computer software
to imitate the cross section function, facilitating the evaluation of a
large number of parameter points in a short period of time. Training is
carried out based on data generated with...
Particle physics experiments typically require that background processes affecting the measurement are taken into account in the data analysis. In collider experiments, this means estimating how large fraction of the observed collision events actually originate from background processes and not from signal events.
The background event yields are usually estimated from simulation or with a...
With the advent of higher energies and higher collision rates, the LHC continues the exciting voyage towards new physics, allowing physicists all over the world to explore a previously unknown territory full of promise. So far the International Particle Physics Outreach Group (IPPOG) international masterclass developers, with the help of physicists and in close contact with teachers, have been...
In my contribution I will review the status of direct detection of dark matter, currently focusing on Weakly Interacting Massive Particle. I will also discuss some future direction and if time allows comment on complementarity with other detection techniques.
Dark Matter and Dark Sector at the LHC
The Standard Model (SM) of particle physics is currently the best theory for describing elementary particles and their interactions, but there are several problems and open questions related to it. For instance it does not incorporate gravity, and it does not explain dark matter, hence there is a need for new fundamental theories of nature beyond the current theory. A theory that addresses...
A search is conducted for new resonant and nonresonant high-mass phenomena in di-electron and dimuon final states. The search uses 36.1 fb−1 of proton-proton collision data, collected at √s = 13 TeV by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% credibility level are set on the cross-section...
A search for the electroweak production of charginos, neutralinos and sleptons decaying to final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb^{-1} of √s=13 TeV proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider. No significant deviations from the Standard Model expectation are observed and results are...
The results of a search for new heavy W' bosons decaying to an electron or muon and a neutrino using proton-proton collision data at a centre-of-mass energy of 13 TeV are presented. The dataset was collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb-1. As no excess of events above the Standard Model predictions...
From the perspective of indirect detection, gamma rays would make excellent messengers of a potential dark matter signal. Not only do they point towards their sources, their energy spectrum may also carry smoking-gun features that allow to pinpoint the particle nature of dark matter. In particular, Bringmann et al. (2017) recently highlighted that excited Standard Model meson states, resulting...
I would like to present my master thesis project, where I study the phenomenology of a supersymmetric model with sneutrino as the NLSP. I look at the tri-lepton signature, two hadronic taus and one lepton (electron or muon), which in my model comes mostly from slepton-sneutrino production. The aim is to improve detectability of this signal using machine learning instead of traditional...
In this talk we will have a brief look at the two decay modes $B^0_s \rightarrow J/\psi \phi$ and $B^0_s \rightarrow\psi(2S)\phi$ and the measurement of the corresponding ratio. To guarantee identical topologies between the two decays we have chosen to only look at the $\psi(2S)\rightarrow \mu^+\mu^-$ and $J/\psi \rightarrow \mu^+\mu^{-}$ modes. A quick look at the peaking backgrounds $B^0_s...
Structure formation in the cold dark matter scenario predicts a large number of small-scale intragalactic dark halos. The existence of these objects has not yet been verified. Can they be detected through gravitational microlensing?
I would like to sketch some of the features of the method for calculating scattering amplitudes presented by Cachazo, He and Yuan. I will give a brief overview of the complex analysis method to make the integrals more manageable. Lastly, I will also provide an example of how to apply the diagrammatic representation of the integrals to calculate the CHY diagrams.
The top quark is the most massive particle in the Standard Model and the precise measurement of it mass could be the key to unveil new physics. The aim of the analysis is to reduce the uncertainty of the measurement by avoiding the modelling of the hadronic decay of the W from the top events. By using the di-lepton channel and, in particular, 5 leptonic observables sensible to the top quark...
Currently, the method for identifying particles in the ATLAS experiment relies on Likelihood estimates constructed from MC simulations. These are good and efficient, but the method has a few shortcomings compared to using ML algorithms. I will present our work so far in using BDTs to classify electrons, some preliminary results, and some of our future hopes and dreams.
I will motivate the study of theories of gravity in the presence of extra spin-2 fields and will then describe a ghost free bimetric theory of gravity, some of its physical implications, and the current status of the theory. In particular, I will focus on the notions of space and time in the theory in the presence of two metric fields.
In bimetric gravity, a number of constraints are needed to ensure that the theory is free of ghosts and propagates the appropriate number of degrees of freedom. I will describe my recent work analyzing the origin and structure of these constraints. The ghost free bimetric theory has six constraints, four of which are first class and are associated with the diffeomorphism invariance of the...
The present landscape and the open questions in particle physics will be briefly reviewed, showing that they call for new means of investigation both towards higher energy and towards more sensitivity to small couplings.
CERN is preparing actively, according to the recommendation of the 2013 European Strategy, for an ambitious post-LHC accelerator complex. The 100km circumference Future...
Particle colliders are quickly reaching a saturation in terms of cost and size: if not with the LHC, then probably with the next generation of colliders. How can we break through this wall and bring accelerators into the next century? The new and blossoming field of Advanced Accelerator Concepts is coming up with novel, exciting technologies aimed at making particle accelerators more compact...
The ATLAS Experiment is currently working on a series of upgrades in preparation for the High-Luminosity LHC, which is scheduled to start in 2026. One such upgrade will be to the inner tracking system. The current Inner Detector will be completely replaced with a brand new, all-silicon Inner Tracker consisting of a pixel detector near to the beam line and a large-area strip tracking detector....
In order to be ready for the HL-LHC, the entire tracking system of the ATLAS experiment will be replaced by a new silicon detector called Inner Tracker (ITK). The new pixel system is currently being developed and could include around 14 m2 of silicon. Here we present the
status of the ongoing development of 3D silicon pixel sensors as well as the work on the very first demonstrator.
The HL-LHC will produce around 200 pp interactions in each bunch crossing, and maintaining the reconstruction performance in this harsh environment is one of the most important experimental challenges to overcome for a successful ATLAS physics program. At the same time, big investments are done to equip the forward region up to |eta| < 4 with tracking capabilities with the ITk. The...
When designing and selecting future collider projects, it is important to understand the physics potential of the different alternatives. Here, we investigate the naturalness reach of the International Linear Collider (ILC) in simple constrained supersymmetric models, and compare it to the reach of the High-Luminosity Large Hadron Collider (HL-LHC), based on the results in [1]. The reach is...
A proposed future circular e+e- collider, the FCC-ee, is suggested to search for sterile neutrinos. The Neutrino Minimal Standard Model, vMSM, is a model of sterile neutrinos, that accommodates explanations for several phenomena of physics beyond the Standard Model. This thesis presents an overview of the theoretical motivation for vMSM, an outline of the experimental conditions at the FCC-ee,...
