Overview will be presented by me or Alice Ohlson
Title can be tuned to match other overviews.
In hadron colliders, the proton constituents that participate in the hard scatter have almost no momentum in the transverse plane. Any imbalance observed in this plane for the products of the scatter can be interpreted as particles escaping detection. Such events can originate from Standard Model processes involving neutrinos, but might also have a more “exotic” origin. One possible...
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...
Viewing dark matter as thermal relics from the early universe necessitates possible dark matter production in accelerator experiments. The dark matter mass range below one GeV, in the "hidden sector", is so far less explored. The Light Dark Matter eXperiment (LDMX) is a proposed fixed target experiment that aims to be sensitive to dark matter around and below the proton mass, where few-GeV...
Dark matter is a theorized, yet unknown form of matter that makes up the majority of the mass of the Universe. One compelling explanation for its origin is the thermal freeze-out mechanism, which posits its mass to be somewhere in the MeV to TeV range. While dark matter with mass above 1 GeV is being thoroughly searched for by an ample amount of experiments, very few experiments to date search...
Baryon number violation (BNV) is needed to explain the origin of the matter-antimatter asymmetry and routinely appears in theories which extend the Standard Model of particle physics. However, BNV is yet to be observed. The HIBEAM/NNBAR program is a two stage set of experiments (HIBEAM then NNBAR) to search for neutron conversions to sterile neutrons and anti-neutrons at the European...
The HIBEAM/NNBAR experimental program will be the cutting-edge free neutron search for n→nbar and n→sterile n oscillations, with an ultimate sensitivity gain of more than three orders of magnitude compared to what was previously achieved. A key component of the program is the annihilation detector which will identify a neutron-antineutron annihilation event within a carbon foil target through...
Within the framework of the massive O($N$) nonlinear sigma model extended to the next-to-leading order in the chiral counting (for $N=3$ corresponding to the two(-quark)-flavor Chiral Perturbation Theory), we calculate the relativistic six-pion scattering amplitude at low energy up to and including terms $\mathcal{O}(p^4)$. Results for the pion mass, decay constant and the four-pion amplitude...
We present a framework to study the interactions among Nambu-Goldstone bosons (NGB), pseudo-NGB (pNGBs) and gauge bosons in Composite Higgs (CH) models at high energies, including operators of order $\mathcal{O}(p^4)$ and $\mathcal{O}(p^2g^2)$ in the chiral expansion and topological terms.
The set of (p)NGBs comprises the longitudinal modes of electroweak bosons, the Higgs boson, and...
In a few recent papers we introduced the chirality-flow formalism for tree-level scattering processes. This method, which builds on the separate SL(2,C) nature of left- and right-chiral states, makes it possible to directly write down the value of a Feynman diagram as a Lorentz scalar.
In this presentation I will review the method and make outlooks towards tree-level implementations,...
We compute the heavy quark momentum diffusion coefficient during the initial nonequilibrium evolution using QCD effective kinetic theory after an ultrarelativistic heavy-ion collision. We observe that the diffusion coefficient approaches its thermal value during the hydrodynamization process. We also give an introduction to thermalization/hydrodynamization in the weak coupling framework.
In the colour decomposition approach to treating the SU(3) colour gauge group in automated event generators, the size of the colour matrix grows factorially with the number of external particles in the process. As such, the treatment of the colour degrees of freedom becomes the bottleneck for high-multiplicity QCD processes. We propose to utilize the large-$N_C$ expansion to obtain a sparse...
Composite Higgs models together with partial compositeness predict the existence of vector-like top-partners above the TeV scale. A wide class of such models show significant barnching ratio of the top-partners decaying into the third generation quarks and exotic pseudo Goldstone bosons, thus opening up new search topologies at the LHC. We systematically study the exotic decays of the...
I am organising the meeting of the Swedish physical society in Lund next year and would like just 5-10 minutes to present it. I hope it can be mixed with partikeldagarna. The theme will be Swedish accelerator based research.
The ESSnuSB is a proposed long-baseline neutrino-oscillation experiment with neutrino beam production at the ESS in Lund and detection of the oscillated beam in a megaton-scale water-Cherenkov detector 360-540 km downstream. The beam would be measured before oscillation at the near-detector (ND) complex close to the production point in Lund, with the dual purpose of providing a direct neutrino...
Picoseconds after the Big Bang, the Universe experienced a phase transition into a state of lower energy, in which nearly all fundamental particles became massive by interacting with the Higgs field. About 13.8 billion years later, the 2013 Nobel Prize in physics was awarded to Englert and Higgs for discovering this mass-generating mechanism, confirmed by the observation of a spin-0 neutral...
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...
In the SHIFT project, funded by the Knut and Alice Wallenberg foundation, experimental and theoretical physicists at Chalmers, Stockholm and Uppsala collaborate in the search for top partners that could potentially solve the Higgs fine-tuning problem. The work includes phenomenological studies of models with top partners, direct searches for top partners in compositeness and supersymmetry as...
The plasma haloscope is a novel method for the detection of the resonant conversion of axions to photons. Traditional cavity haloscopes compensate for the momentum mismatch between the axion and the massless photon by breaking translational invariance, for instance through implementing physical structures on the order of the axion Compton wavelength. This makes reaching higher axion masses a...
TeV halos have become a new class of astrophysical objects which were not predicted before their recent observation. They offer evidence that diffusion around sources (concretely, pulsars) is not compatible with the effective average diffusion that our models predict for the Galaxy. This directly impacts Galaxy formation, our knowledge of the propagation process throughout the Galaxy and our...
The local flux of cosmic-ray positrons has been measured to great precision by the AMS-02 experiment. At high energies, the positron flux is dominated by nearby pulsars that convert their spindown energy into electron-positron pairs. Interestingly, simple pulsar models predict sharp spectral features in the positron flux, while AMS-02 observations indicate that the positron spectrum is...
The derivation of indirect constraints on dark matter annihilation in our Galaxy from cosmic-ray antiprotons requires computationally expensive simulations of cosmic-ray propagation. I will present a new method based on Recurrent Neural Networks that significantly accelerates simulations of cosmic-ray antiproton spectra from secondaries and dark matter and achieves an excellent accuracy....
We develop a formalism to describe electron ejections from graphene by dark matter (DM) scattering for general forms of spin 1/2 DM electron interactions. This novel formalism allows for accurate prediction of the daily modulation signal expected from DM in upcoming direct detection experiments employing graphene sheets as target material. The general interaction is captured using...
IceCube-Gen2 is a planned extension of the IceCube Neutrino Observatory at the South Pole designed to study the high-energy neutrino sky from TeV to EeV energies. IceCube-Gen2 will increase the annual rate of detected neutrinos by a factor of 10 by deploying 120 new strings with attached optical sensors in the ice sheet, and through the addition of a radio array expand the observed energy...
Blazars are among the most powerful steady sources in the Universe. Multi-messenger searches from blazars have traditionally focused on their gamma-ray emission, which can be produced simultaneously with neutrinos in photohadronic interactions. However, X-ray data can be equally vital to constrain the SED of these sources, since the hadronically co-produced gamma-rays get absorbed by the...
