Conveners
Sektionen för elementarpartikel och astropartikelfysik: AF Borgen: Nya Fest
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Sektionen för elementarpartikel och astropartikelfysik: AF Borgen: Nya Fest
- David Silvermyr (Lund University (SE))
- Rikkert Frederix (Lund University)
Sektionen för elementarpartikel och astropartikelfysik: Institutionen för astronomi och teoretisk fysik, Lundmarkssalen
- There are no conveners in this block
This contribution will present the current activities in the KTH team working on the ATLAS experiment at the LHC. An overview of topics ranging from luminosity studies and ongoing Run-2 analysis topics to HL-LHC upgrade work will be discussed.
A search for a long-lived supersymmetric particle at ATLAS in multi-jet events with a displaced vertex. The talk will focus on event selection, suppression of background through means of vetoing certain detector regions as well as the final limits set by the search.
We develop a new class of experimental search for new Higgs-like spin-0 particles with the ATLAS experiment at LHC. We focus on the essentially unexplored asymmetric Higgs decay $X \rightarrow SH$, where $X$ and $S$ denote two BSM spin-0 Higgs-like neutral particles and $X$ is the heavier of the two ($m_X > m_S$). $H$ denotes the already experimentally known Higgs boson with a mass of $m_H =...
After the discovery of the Higgs boson in 2012, an important test of the electroweak symmetry breaking would be to establish evidence of the Higgs boson self-coupling, which can be achieved through a measurement of Higgs boson pair production. In the Standard Model (SM), di-Higgs events are dominantly produced in gluon-gluon fusion processes at the LHC, e.g. involving the Yukawa coupling to...
An elegant explanation for the origin and observed abundance of dark matter in the Universe is the thermal freeze-out mechanism. Within this mechanism, possible masses for dark matter particle candidates are restricted approximately to the MeV - TeV range. The GeV-TeV mass range is being explored intensely by a variety of experiments searching for Weakly Interacting Massive Particles. The...
Growing amounts of research data require new computing solutions to manage increased data storage, utilisation, and analysis capabilities. The EU-funded SMARTHEP project, where Lund is one of the founding participants, will break from the traditional paradigm of ‘first collect data, then analyse it’ and move towards real-time analysis (RTA) where data collection and analysis become synonymous,...
Abstract: Machine learning methods are now ubiquitous in physics, but often target objectives that are one or two steps removed from our physics goals. A prominent example of this is the discrimination between signal and background processes, which doesn’t account for the presence of systematic uncertainties — something crucial for the calculation of quantities such as the discovery...
We go beyond the state-of-the-art by combining first principal lattice results and effective field theory approaches as Polyakov Loop model to explore the non-perturbative dark deconfinement-confinement phase transition and the generation of gravitational-waves in a dark Yang-Mills theory. We further include fermions with different representations in the dark sector. Employing the...
About a picosecond after the Big Bang, when the universe had cooled down to a temperature of around 100 GeV, the electroweak symmetry was broken, as the Higgs field condensed into a state with a non-zero vacuum expectation value. This process is known as the Electroweak Phase Transition (EWPT). If the EWPT was a first-order phase transition, it was an abrupt and violent process with formation...
Gravitational waves offer a new way to understand the Higgs via the Electroweak phase transition. The signal from such a transition would, if observed, give crucial information of the underlying physics. Provided that the transition is first-order and proceeds through nucleating bubbles. Yet theoretical predictions of the gravitational-wave spectrum are rife with uncertainties. Large ones at...
We study the impact of an alternate cosmological history with an early matter-dominated epoch on the freeze-in production of dark matter. Such early matter domination is triggered by a meta-stable matter field dissipating into radiation. In general, the dissipation rate has a non-trivial temperature and scale factor dependence. Compared to the usual case of dark matter production via the...
In this talk, I will present a short overview of the connection between particle physics and phase transitions in the early and very early universe. I will then focus on phase transitions during inflation and present recent results on how to use the stochastic spectral expansion to perform phenomenology calculations. I will also talk about the interplay between the electroweak phase...
We suggest an appealing strategy to probe a large class of scenarios beyond the Standard Model simultaneously explaining the recent CDF II measurement of the W boson mass and predicting first-order phase transitions (FOPT) testable in future gravitational-wave experiments. Our analysis deploys measurements from the gravitational waves channels and high energy particle colliders. We discuss...
I will present a new class of renormalisable models, labelled Fermion Portal Vector Dark Matter, consisting of a dark SU(2)D gauge sector connected to the Standard Model through a Vector-Like fermion mediator, not necessarily requiring a Higgs portal, in which a massive vector boson is the Dark Matter candidate. Multiple realisations are possible, depending on the properties of the VL partner...
Two years ago, we introduced a new method to calculate Feynman diagrams more efficiently and transparently, the Chirality-Flow formalism. In this framework, which builds on the spinor-helicity formalism, analytic, tree-level Standard Model Feynman diagrams can be written down almost immediately as a complex number, without the need for intermediate algebra. In this talk, as a proof-of-concept,...
This contribution provides an overview of the status of the Knut and Alice Wallenberg project “Light Dark Matter”, a collaboration between experimental and theoretical particle and nuclear physicists from Lund University, Chalmers and Stockholm University. The project addresses the possible existence of sub-GeV dark matter in a very comprehensive way. Its activities range from the setup of a...
SHIFT (Solving the Higgs Fine-tuning problem with Top partners) is a Swedish theory-experiment collaboration with participants from Chalmers, Stockholm University and Uppsala, which is funded by KAW between January 2018 and June 2023. The aim of the project is to develop new models and search for top partners which could potentially explain the low mass of the Higgs boson, as well as perform...
Beam dump experiments place strong constraints on the parameter space of interesting sub-GeV dark matter (DM) models. We extend the current literature, which mainly focuses on the predicted signals of scalar and fermionic DM at beam dump experiments, by considering simplified DM models where the Standard Model is extended by one vector DM candidate along with one spin-1 or spin-0 mediator. In...
We develop a novel formalism to describe the scattering of dark matter (DM) particles by electrons bound in detector materials such as silicon, germanium and graphene for a general form of the underlying DM-electron interaction. By applying non-relativistic effective field theory methods, we find that the DM and material physics factorise into a handful of DM and material "response functions"....
The ESSnuSB experiment is a proposed long-baseline neutrino beam experiment that will measure the CP violation in the lepton sector. The CP violation will be determined by measuring the neutrino beam at the second probability maximum for muon neutrino oscillation into electron neutrinos, where the systematic uncertainty in the measurement is significantly reduced compared to the first...
The IceCube Neutrino Observatory, built into a cubic kilometer of ice at
the South Pole, was completed in 2010 and has been in continuous
operation since then. Discovering the diffuse astrophysical neutrino
flux in 2013, and pinpointing the first high-energy neutrino sources
starting in 2018, IceCube has inaugurated the era of neutrino
astronomy. Progress has been not only incremental...
X-ray emission from blazars can be a useful tool to constrain their neutrino flux, assuming hadronic gamma-rays cascade down due to absorption inside source and secondary pair production. This approach was useful in disfavoring a single zone model for high-energy neutrino emission from the blazar TXS 0506+056, and more recently in the case of FSRQ PKS 1502+106 to hint at the presence of a...
Large-scale neutrino telescopes like IceCube monitor for supernovae using low energy neutrinos O(10 MeV), with a detection horizon out to the Magellanic Clouds. However, some models predict the emission of high-energy neutrinos O(>TeV) in core-collapse supernovae through the interaction of the ejecta with the circumstellar material or through choked jets. In this talk, I will explore the...
The IceCube Neutrino Observatory is the world-leading instrument for astrophysical neutrino measurements. In the coming decade, we plan for IceCube-Gen2, which will include an expanded optical array with a factor of ~ 8 more instrumented volume and the addition of a radio array to extend the energy reach up to the EeV scale. Gen2 will move from the discovery era of astrophysical neutrinos to...
Pulsars dominate the local cosmic-ray positron flux at high energies by producing electron-positron pairs from their spindown energy. While the AMS-02 experiment, that measures the cosmic-ray flux to great precision, shows that the positron flux is very smooth, simple simulations of pulsar models predict sharp spectral features. In this work, we add several mechanisms to model the local...
In this talk I present the status of the "HIBEAM at the ESS" research project. The High Intensity Baryon Extraction and Measurement (HIBEAM) is the first stage of the two-stage experiment HIBEAM-NNBAR program and addresses major open questions in modern physics, in particular the origin of the observed matter-antimatter asymmetry and the nature of dark matter, with unique discovery potential,...
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. We will also discuss the hardware activities in our group, particularly our contributions to the ongoing and planned detector upgrades in light of...
The European Spallation Source (ESS), currently under construction in Lund, will be a multi-disciplinary international laboratory that, at full specifications, will operate the world's most powerful pulsed neutron source. Taking advantage of the construction of such a facility, the HIBEAM/NNBAR collaboration has proposed a two-stage program of experiments to conduct a high precision series of...
