Review of the Swedish contribution to the operations of the ATLAS detector and monitoring and optimising its performance.
Review of the Swedish activities exploring physics of the Higgs-sector in the ATLAS experiment.
Review of the Swedish activities searching for signatures of beyond the standard model physics with the ATLAS detector.
The Large Hadron Collider (LHC) will be upgraded by the end of the decade to produce 200 collisions per proton-proton bunch crossing, 10 times the current LHC’s design. This upgrade, the High Luminosity LHC (HL-LHC), will allow us to reach an integrated luminosity of 3000–4000 fb^-1, probing rarer processes and increasing sensitivity to unobserved processes. The HL-LHC presents a significant...
Two major ingredients of a composite Higgs model are vacuum misalignment and partial compositeness. The former is essential to trigger the electroweak symmetry breaking, while the latter can explain the mass hierarchy of the quarks. The partial compositeness mechansim employes a mixing between the SM quarks and vector-like quarks, arising from a new confining sector, via four-Fermi operators....
One of the currently most widely researched questions in particle physics is “What is dark matter?”. The Stealth Dark Matter theory identifies it with a stable state in a new, strongly coupled, dark sector extending the Standard Model. The constituents of the new sector, the dark quarks, form bound states in analogy with the SM QCD sector, giving rise to dark mesons, some of which can decay...
The Light Dark Matter eXperiment (LDMX) is currently being designed to search for Dark Matter (DM). It targets a window of opportunity to explore a dark sector in the MeV-GeV mass region where DM of thermal origin has not yet been excluded. This talk will outline the motivation and current status of LDMX, highlighting some of Sweden's and Lund University's recent contributions to the design...
We present the proposal for a general-purpose intensity-frontier experimental facility BDF/SHiP, operating in beam-dump mode at the CERN SPS accelerator in the existing SPS ECN3 experimental area. This proposal is part of the ongoing decision process focused on the beyond-LS3 physics program in ECN3, which should come to conclusion by the end of 2023. The SHiP experiment aims to search for...
The HIBEAM/NNBAR program is a multi-stage series of experiments to search for baryon number violation via neutron conversions to sterile neutrons and/or anti-neutrons. In this talk, I'll describe the theoretical motivation, the status of the project and sensitivities expected.
The European Spallation Source (ESS), presently under construction in Lund, Sweden, is a multidisciplinary international laboratory that aims to become the world's most powerful pulsed neutron source. At its design performance, it will also be at the "intensity frontier" of particle-physics research and provide unique opportunities to solve open questions about the fundamental building blocks...
In the ALICE group at Lund, we analyse data from proton-proton and heavy-ion collisions to gain a better understanding of the connection between microscopic QCD processes and the properties of nuclear matter at high temperature and energy density. I will also discuss the hardware activities in our group, particularly our contributions to the ongoing and planned detector upgrades in light of...
The Light Dark Matter eXperiment (LDMX) is a fixed-target experiment that will be placed at the LCLS-II electron beamline at SLAC, sensitive to production of sub-GeV dark matter with missing momentum and missing energy signatures. This precision search for rare dark matter production requires strong veto capabilities to separate those events from standard model background processes. After...
The Light Dark Matter eXperiment (LDMX) aims to perform a zero background search for light dark matter. The ability of the experiment to veto standard model backgrounds has been studied in detail based on Geant4 simulations. A critical background process for the detector design comes from photonuclear reactions of few-GeV photons with tungsten. In Geant4, these are modeled using the Bertini...
Sub-GeV dark matter (DM) has been gaining significant interest in recent years, since it can account for the thermal relic abundance while evading nuclear recoil direct detection constraints. Such light DM must carry a larger energy to be probed, either directly or through missing energy/momentum, making beam dump and fixed target experiments ideal for this mass range. Here, we extend the...
In recent years, detailed studies of three-pion systems have become possible in lattice QCD. This has in turn led to interest in 3-to-3 scattering of pions in the chiral perturbation theory framework, which complements the lattice results. In particular, it provides a valuable handle on finite-volume effects and the pion mass dependence. I present our derivation of the next-to-leading order...
The ESSnuSB design study is entering a new phase with a second four-year design study 2023-2026, ESSnuSBplus, funded by Horizon Europe. One of the ESSnuSBplus additions to ESSnuSB will be the design study of a low-energy nuSTORM (neutrinos from stored muons) facility based on the use of the ESS accelerator and the ESSNUSB accumulator-ring as injector complex. The nuSTORM facility consists of a...
Higgs boson pair production (HH) is traditionally considered to be of particular interest for a measurement of the trilinear Higgs self-coupling. Yet it can offer insights into other couplings as well, since - in an effective field theory (EFT) parameterisation of potential new physics - both the production cross section and kinematical properties of the Higgs boson pair depend on various...
We discuss the possibility of probing BSM physics via di-Higgs production, in particular light stops. We performed an amplitude-level analysis of Higgs pair production at the LHC and show what types of deviations one could expect and how they arise from different new physics contributions. The toolbox can be used also to different scenarios with additional colored scalars coupling to the Higgs...
I propose the creation of a Light Exotics Effective Field Theory (LEX-EFT) catalog - a generic framework to capture all interactions between the Standard Model (SM) and all (or at least a large class of) theoretically allowed exotic states beyond the Standard Model (bSM), indexed by their SM and bSM charges. . This framework. for onshell exotics, which subsumes beyond the Standard Model...
I will present a new computer program, feyntrop, which uses the tropical Monte Carlo approach to evaluate Feynman integrals numerically.
In order to apply this approach for physical kinematics, we introduce a new parametric representation of Feynman integrals that implements the causal $i\varepsilon$ prescription concretely while retaining projective invariance. feyntrop can...
Observations by AMS-02 on the International Space Station have tentatively detected approximately 10 events that are consistent with antihelium nuclei. Such a detection would be of significant theoretical interest due to the difficulty in producing any detectable antihelium flux through standard model interactions. In this talk, I will discuss the state of these observations, the state of...
High-energy cosmic-ray electrons and positrons cool rapidly as they propagate through the Galaxy, due to synchrotron interactions with magnetic fields and inverse-Compton scattering interactions with photons of the interstellar radiation field. Typically, these energy losses have been modelled as a continuous process. However, inverse-Compton scattering is a stochastic process, characterised...
XENONnT, the latest detector of the XENON Dark Matter program, shows an unprecedentedly low background which facilitates searches for new, very rare phenomena with high sensitivity. The detector which was designed to look for elusive dark matter particles holds almost 6000 kg of ultrapure liquid xenon as a target for particle interactions. It is installed inside a water Cherenkov active muon...
We employ a non-relativistic effective theory to model dark matter (DM) induced electron ejections from graphene and carbon nanotubes (CNTs), materials currently in the R&D phase for direct detection experiments. We employ Density Functional Theory to model the material properties of graphene, and obtain observable ejection rates for arbitrary forms of scalar and spin-1/2 DM. We show how the...
One of the strongest bounds on MeV-scale Axion-Like Particles (ALPs) interacting with photons is derived from the non-observation of a gamma-ray burst following Supernova (SN) 1987A. We strengthen this bound by including photon coalescence as an efficient production process of heavy ALPs. Furthermore, we present in some detail a new analytical method for calculating the predicted gamma-ray...
A Dark Matter Science Project is being developed in the context of the ESCAPE and EOSC-Future projects as a collaboration between scientists in European Research Infrastructures and experiments seeking to explain the nature of dark matter (such as HL-LHC, KM3NeT, CTA, DarkSide).
The goal of this ESCAPE Science Project is to highlight the synergies between different dark matter communities...
Based on the recent article [2023.02399], we discuss the LISA potential for finding evidence of New Physics from measurements of the Stochastic GW Background (SGWB). As a benchmark scenario, we study a version of the low-scale Majoron model equipped with lepton number symmetry and an inverse seesaw mechanism for neutrino mass generation. In particular, we discuss under which circumstances the...
Thermal field theory is indispensable for describing hot and dense systems. Yet perturbative calculations are often stymied by a host of energy scales, and tend to converge slowly. This means that precise results require the apt use of effective field theories. In this talk I describe how the effective description of slowly varying gauge fields, known as hard thermal loops, can be extended to...
Among the theoretical particles that could explain dark matter, axions make an ideal candidate. They can be produced in the early Universe and make up the observed abundances, permeating the universe as an invisible wave. In recent years, the efforts to build a kind of radio that would tune to this unique frequency has intensified, with conventional techniques failing to look for high...
Recently, Lawson et al. (2019) proposed a plasma haloscope, based on metamaterials for the search of axions. In previous plasma haloscopes, the size of resonant cavities is limited due to the Compton wavelength of axion, making it impractical to scale detector sizes to search for higher-mass axions. However, the proposed metamaterial based detector has the potential of scanning through a...
IceCube is a cubic-kilometre high-energy neutrino observatory at the South Pole. By now, it has accumulated more than 10 years of data and has started the field of high-energy neutrino astronomy with the detection of diffuse astrophysical neutrinos and evidence for a few point sources. While more data is still taken, the existing 10+ years of data is also constantly re-analyzed with better...
The IceCube Neutrino Observatory deployed 5160 digital optical modules (DOMs) on 86 cables, called strings, in a cubic kilometer of deep glacial ice below the geographic South Pole. These record the Cherenkov light of passing charged particles, for example muons from cosmic rays or created by neutrinos. Knowledge of the DOM positions is vital for event reconstruction. While vertical positions...
The IceCube Neutrino Observatory is uniquely sensitive to MeV neutrinos emitted during a core-collapse supernova, with potential applications beyond supernova neutrino bursts. In this talk, we describe a fast response analysis that can be used to respond to external alerts, such as those from the Ligo-Virgo-Kagra detector for gravitational waves. Additionally, we will discuss the...
With the LHC Run-3 currently underway, the global high energy physics community is actively working to define the future of collider particle physics. The European Strategy for Particle Physics has identified an e+e- Higgs factory as its top priority and the first step towards a future hadron collider with very high energy. To address these goals, a staged Future Circular Collider (FCC) is...
The Future Circular Collider (FCC) is a proposed new accelerator at CERN, designed to operate in a 90 km tunnel and to run with an integrated program. The first stage, FCC-ee, will be an electron-positron collider serving as a Higgs, electroweak, and top factory at the intensity frontier. In addition to the great possibility at FCC-ee to test the Standard Model to high precision, it also has...
The Dark Matter question is among the most fundamental unsolved problems of modern day physics. One possible candidate for Dark Matter are Dark Mesons, a type of Stealth Dark Matter. They are predicted by extending the Standard Model with a strongly coupled dark sector. Similar to quarks they appear in confined states like baryons and mesons. Their coupling to the Higgs field allows...
The Large Hadron Collider (LHC) will be upgraded to the High-Luminosity LHC (HL-LHC) by the end of this decade, with five times larger luminosity and 200 inelastic collisions per proton-proton bunch crossing. Thus, the ATLAS detector is challenged to survive the stronger radiation and the increased particle flux. As a result, the new ATLAS Inner Tracker (ITk) will replace the current one with...
The High Luminosity-Large Hadron Collider (HL-LHC) will reach an approximate pile-up of 200 collisions per bunch crossing, ten times more than the current Large Hadron Collider. Beginning operation at the end of the decade, it will accumulate 3000 fb-1, increasing the chances of observing new processes and allowing measurement of rare processes with higher precision. Moreover, the pile-up...
The planned in-ice radio array of IceCube-Gen2 at the South Pole will provide unprecedented sensitivity to ultra-high-energy (UHE) neutrinos in the EeV range. The ability of the detector to measure the neutrino’s energy, direction, and flavor is of crucial importance. This contribution presents an end-to-end reconstruction of all these quantities for both detector components of the hybrid...
Dark matter is one of our universe's greatest mysteries and very little is known about what it is. One of the dominating theories, that dark matter originates from an early universe thermal relic, indicates that it interacts with the Standard Model. If this is the case, dark matter can be produced at accelerators. The Light Dark Matter eXperiment, LDMX, is an upcoming experiment that will join...
One common issue in vastly different fields of research and industry is the ever-increasing need for more data storage. With experiments taking more complex data at higher rates, the data recorded is quickly outgrowing the storage capabilities. This issue is very prominent in LHC experiments such as ATLAS where in five years the resources needed are expected to be many times larger than the...
The Light Dark Matter eXperiment (LDMX) is a planned fixed-target missing-momentum experiment being designed with unique sensitivity for the largely experimentally unexplored MeV-GeV mass range for light dark matter. A key challenge for LDMX is its efficiently at vetoing rare background events such as neutral hadrons stemming from photonuclear reactions in both the target and the setup itself....
The IceCube Neutrino Observatory has full sensitivity for core-collapse supernovae within the Milky Way and model-dependent sensitivity for the Large and Small Magellanic clouds. The upcoming extension of IceCube, IceCube-Gen2, offers the opportunity to implement new trigger and sensor concepts promising to improve IceCube's CCSNe sensitivity. Coincidence triggers on the one hand allow us to...
The universe shows signs of containing some invisible matter, known as dark matter. There are many possible constituents for dark matter, one such being light dark matter which would interact with ordinary matter through a new mediator force and have masses in the range of a few MeV to GeV. The light dark matter mass range is largely unexplored experimentally. The Light Dark Matter eXperiment,...
We investigate the phenomenology of the R-Parity Violating MSSM (RPV-MSSM) for the case of small RPV couplings. For the first time in the literature, we provide a general and model-independent treatment of its phenomenology at the LHC. We have compiled a minimal set of searches that provide complete coverage at the LHC, and we call this the "RPV Dictionary". We also developed ABC-RPV, a...
In high energy physics (HEP), accurately reconstructing charged particle
trajectories is a challenging task. The classical Kalman filter estimates track
parameters with uncertainties through prediction, filter, and smoother steps.
Precisely aligning detector components increases sensitivity to new physics and
improves particle identification efficiency. The ATLAS alignment solver...
