Partikeldagarna 2021

Nov 22, 2021, 9:30 AM → Nov 23, 2021, 7:00 PM Europe/Stockholm

Palmstedt (Chalmers Conference Centre)

Caterina Doglioni (Lund University (SE)), Gabriele Ferretti, Riccatdo Catena (Chalmers University of Technology), Rikkert Frederix (Lund University), Sten Hellman (Stockholm University (SE))

Partikeldagarna 2021 will be held at Chalmers University of Technology on November 22nd-23rd, 2021. The meeting is organised by a local organising committee and members of the Particle and Astroparticle Physics Section of the Swedish Physical Society (Fysikersamfundet). It starts on Monday at 9:30 am with a welcome coffee and ends on Tuesday at 6 pm (the social dinner is on November 22nd). 

The aim of the meeting is to have a status report and a professional discussion on current particle and astroparticle physics research in Sweden. Partikeldagarna 2021 will follow the same structure as previous years, with a mix of talks given by individual (preferably young) researchers presenting their work, group reports and summaries from funding agencies and international organisations where Sweden is represented.

We strive for a safe, in-person event. To this end, Partikeldagarna 2021 will take place in a lecture hall that can host almost 300 participants under normal circumstances. Unfortunately, this implies a slightly higher conference fee than in previous editions, and a contribution from both in-person and virtual participants. Virtual participation will be made possible via a livestream of all talks. This option is intended for those who prefer not to attend the event in person because of the Covid-19 pandemic.  

We know that these are extraordinary times. We nevertheless hope to see you in person at Chalmers soon!

The registration fee for in-person (virtual) participation is 750 SEK (550 SEK). See payment instructions link.

As in previous years, participation to Partikeldagarna is restricted to members of the Swedish Physical Society. Membership can be obtained through the payment of an annual fee. Master students are exempted from this restriction. Further information can be found here.

Partikeldagarna will feature two invited speakers covering hot topics in particle and astroparticle physics:

- Felix Kahlhoefer, RWTH Aachen University, Germany; "Dark matter beyond the WIMP paradigm"

- Anna Driutti, University of Pisa, Italy; "First results from the Muon g-2 experiment"

The event will also feature a session on diversity in physics. One of the speakers in that session is Pernilla Wittung-Stafshede, leader of Genie (Gender Initiative for Excellence), who will be happy to engage in a discussion on gender in physics during the coffee break following her talk.

Registration deadline: 17/10/2021

Abstract submission deadline: 31/10/2021

Venue: Chalmers Conference Centre, Palmstedt room (see address and link to google maps below)

 

Organisers: Riccardo Catena (Chalmers), Caterina Doglioni (Lund/University of Manchester), Gabriele Ferretti (Chalmers), Rikkert Frederix (Lund University), Sten Hellman (Stockholm University)

Find your way on Chalmers' campus

Find your way to Chalmers

Monday, November 22

9:30 AM Welcome coffee

Introduction

Convener: Riccardo Catena

Monday morning session: Experimental particle physics

Convener: Sten Hellman

1 Overview of the Lund ALICE group's activities

Overview will be presented by me or Alice Ohlson

Title can be tuned to match other overviews.

Speaker: Peter Christiansen (Lund University (SE))

p_christiansen_lund_alice_animated.pdf

2 Event-structure dependence of light-flavour-hadron production in pp collisions with ALICE

Speaker: Oliver Matonoha

3 Report from Stockholm university ATLAS group

Speaker: Xuanhong Lou (Stockholm University (SE))

Partikeldagarna_211122.pdf

4 Search for Dark Matter in events with missing transverse momentum and a Higgs boson decaying into b-quarks with the ATLAS detector

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 explanation for the nature of Dark Matter is that it consists of stable, weakly interacting, neutral particles that would also escape detection. To be able to study these particles their production has to be accompanied by a visible object like a jet, a photon, a W or a Z boson or a Higgs boson. Compared to the other objects, the Higgs boson offers a significant advantage: it will not be produced from initial state radiation but serves as a direct probe of the interaction with the Dark Matter. The search presented in this contribution is looking for such events through the Higgs decay channel to b-quarks. The final state signature will thus consists of large missing transverse momentum and two b-jets. The signal region is a region of phase space defined to select events of interest while rejecting Standard model background as much as possible. To estimate the remaining background events dedicated phase space regions are defined, the control regions. The corresponding selections are applied to simulated samples to determine the contribution of signal and background events in the total event rate. The estimated yields depend on a number of factors: detector resolution, calibrations, choices made in modeling parameters. These factors contribute to the uncertainty on the estimated yields and are carefully calculated. The signal and control region definitions are applied to the collected data and a profile likelihood fit is performed simultaneously in these regions to extract a possible signal. This contribution will present the results from analyzing the full 13 TeV data set recorded with the ATLAS detector from 2015 to 2018.

Speaker: Eleni Skorda (Lund University (SE))

PartikeldagarnaTalkEleniSkorda.pdf

5 Status and Prospects of Light Dark Matter eXperiment

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 sub-GeV region occurs naturally in Hidden Sector dark matter models, but has been tested much less by experiments to date. Exploring this mass range is imperative as part of a comprehensive Dark Matter search programme, but requires new experimental approaches.

The freeze-out mechanism assumes a non-gravitational interaction between dark and ordinary matter, which necessarily implies a production mechanism for dark matter at accelerator experiments. Recent advancements in particle accelerators and detectors in combination with software developments like machine learning techniques open new possibilities to observe such processes.

The planned Light Dark Matter eXperiment (LDMX) is an electron-beam, fixed- target experiment that exploits these developments, enabling us to observe processes orders of magnitudes rarer than what is detectable today. The key to this is a multi-GeV beam providing a few electrons 46-million times per second, and a detector that monitors how each individual electron interacts in the target — for up to $10^{16}$ electrons. First beam for commissioning the experiment is expected in early 2024 at SLAC, Stanford, marking the starting point of a first data taking period of about one and a half years. A second phase with higher beam-energy and -intensity is foreseen soon thereafter.

This presentation will give an overview of the theoretical motivation and the different components of the LDMX detector concept, as well as the main experimental challenges and how they are addressed. It will further discuss projected sensitivities and possible future upgrades towards covering a large portion of the viable phase-space for sub-GeV thermal relic dark matter and other models.

Speaker: Ruth Pottgen (Lund University (SE))

LDMX_PD_Nov2021.pdf

6 Light Dark Matter eXperiment Rejection of Photon Induced Background at 8 GeV

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 electrons will possibly recoil in a thin tungsten target through some dark matter direct production model, yielding measurable missing momentum. At higher energies the production cross-section of some models should increase, motivating the study of running the LDMX at 8 GeV, above the previously studied 4 GeV.

Due to the small and unknown rate of dark matter production, the experiment aims to ideally reject all of the background events out of approximately $10^{14}$ expected electrons on the target. The electrons will also recoil in the tungsten target through normal bremstrahlung. But through various photo-nuclear interactions, the resulting photon can end up in hard-to-catch hadronic final states that may appear as missing momentum. The forward electromagnetic calorimeter of LDMX can be used to veto these events, using a boosted decision tree trained primarily to distinguish between dark matter signal and such photon induced background events.

Monte Carlo simulations of a first run at 4 GeV showed a $10^{-13}$ background rejection. Higher energies could expect higher rates of dark matter production in some models, as well as it being easier to measure the energetic by-products of backgrounds events. The rates of some background final states may even decrease at higher energies. This study concerns these possible improvements in background rejection at an 8 GeV second run of LDMX and how the sensitivity to dark matter production is increased, a necessary endeavor when the coupling between dark matter and standard model particles is unknown and at most very small.

Speaker: Erik Wallin (Lund University (SE))

Erik_Wallin_Partikeldagarna_2021(1).pdf

7 simulation and testing of the Light Dark Matter eXperiment prototype trigger and hadronic calorimeter

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 for light dark matter - dark matter with a mass between 1 MeV and 1 GeV. The Light Dark Matter eXperiment (LDMX) is one of those few. It consists of a 4-16 GeV electron beam shot at a fixed tungsten or aluminium target, the results of which are analysed using missing-momentum techniques to find dark matter creation events. It can therefore conclusively test most models of light dark matter. First commissioning data from the LDMX is expected as early as fall 2023.
In order to build a detector sensitive enough to detect dark matter events, its detecting components - the trigger, trackers, electromagnetic calorimeter, and hadronic calorimeter - must be thoroughly tested and their behavior exactly described. To achieve such precise instrumentation, a prototype of the trigger has been tested this October, and a prototype of the hadronic calorimeter will be tested this coming March. One objective of the test beam measurements was to ensure its proper timing and function of the trigger. Another objective will be to tune the simulation of the hadronic calorimeter. For this purpose, a detailed simulation of each has been developed.
This contribution focuses on the first results from a Geant4 based simulation of the prototype hadronic calorimeter, using different beam characteristics, embedded in the LDMX software framework. Additionally, it focuses on the experimental results of the LDMX trigger prototype that was recently tested under a beam.

Speaker: Peter Gyorgy (Lund University (SE))

Partikeldagarna presentation.pdf

8 Progress towards a program of searches for neutron conversions at the European Spallation Source with the HIBEAM/NNBAR experiment

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 Spallation Source. The ultimate aim of the program is extend the sensitivity of BNV searches by three orders of magnitude compared with previous searches. This talk shows progress on all major aspects of the program: the neutron moderator source, beamline and focusing and detector design. Estimates of the sensitivity of the searches are also given. A focus is placed on the HIBEAM stage.

Speaker: Bernhard Meirose (Stockholms Universitet)

Partikeldagarna_Meirose_final.pdf

9 Updates on the HIBEAM/NNBAR Prototype Calorimeter at Stockholm

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 the reconstruction of a number pions with kinetic energies below ~500 MeV. This low energy regime is a challenge for calorimetry due large fluctuations in energy depositions from showers created in traditional sampling calorimeters. A novel, hybrid calorimeter design is proposed for the detector: a hadronic range measurement using scintillating plastic staves and wavelength shifting fibres followed by an energy measurement using lead glass blocks. A prototype calorimeter system is under construction at Stockholm University. The prototype includes 50 scintillator staves and 12 lead glass blocks. Both detectors are read out with silicon photomultipliers. This talk will present the design, construction, and readout electronics of the prototype system. A short description will also be given of plans to supplement the calorimeter prototype with a Time Projection Chamber. The combined system will be studied at test beams at the ESS and elsewhere.

Speaker: Katherine Dunne (Stockholm University (SE))

kdunne-nnbar-calo-prototype-partikeldagarna2021.pdf

10 Progress on the design of an annihilation detector for the HIBEAM/NNBAR program at the European Spallation Source

Speaker: Sze Chun Yiu

2021-11-23_Parikledagarna.pdf

12:30 PM Lunch

Monday afternoon session 1: Plenary talks

Convener: Gabriele Ferretti

11 Dark matter beyond the WIMP paradigm

Speaker: Felix Kahlhoefer

Partikeldagarna.pdf

12 First results from the Muon g-2 experiment

Speaker: Anna Driutti

3:30 PM Coffee break

Monday afternoon session 2: Theoretical particle physics

Convener: Rikkert Frederix

13 The six-pion amplitude

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 in the case of $N$ (meson) flavors at $\mathcal{O}(p^4)$ will be also presented.

Speaker: Tomáš Husek (Lund University (SE))

Husek_Partikeldagarna2021.pdf

14 NNLO Positivity Bounds on Chiral Perturbation Theory for a General Number of Flavours

We present positivity bounds, derived from the principles of analyticity, unitarity and crossing symmetry, that constrain the low-energy constants of chiral perturbation theory. Bounds are produced for 2, 3 or more flavours with equal meson masses, up to and including next-to-next-to-leading order, using the second and higher derivatives of the amplitude. We enhance the bounds by using the most general isospin combinations posible (or higher-flavour counterparts thereof) and by analytically integrating the low-energy range of the amplitude. In addition, we present a powerful and general mathematical framework for efficiently managing large numbers of positivity bounds.

Speaker: Mattias Sjö

bounds-talk.pdf

15 Towards the precise description of Composite Higgs models at colliders

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 possibly other scalar states from the dynamical spontaneous electroweak symmetry breaking.
The framework is implemented in a collider simulation tool especially suited for the study of Goldstone Boson Scattering (GBS), which includes vector boson scattering (VBS), di-Higgs production via vector boson fusion (VBF) and the pair production of other pNGBs via VBF.

Speaker: Diogo Buarque Franzosi (Chalmers University of Technology)

CHLag.pdf

16 Simplifying calculations with chirality-flow

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, calculations beyond leading order and resummation.

Speaker: Malin Sjödahl

MSPartikeldagarna2111.pdf

17 Heavy quark momentum diffusion coefficient during the hydrodynamization in heavy-ion collisions

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.

Speaker: Jarkko Peuron

PartikelDagarna.pdf

18 The colour matrix at next-to-leading-colour accuracy

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 colour matrix at next-to-leading-colour accuracy which reduces the computation complexity from a factorial to a polynomial scaling at the parton-level. We examine this efficiency for both the fundamental and the colour-flow decompositions for processes with up to two quark pairs. This work is the first step towards an efficient and accurate event generator for processes with 8-9 QCD partons or more.

Speaker: Timea Vitos (Lund University)

Partikeldagarna_2021_vitos.pdf

19 A reappraisal of top-partner hunting

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 top-partners in the partial compositeness framework. We aim to bridge the gap between the simplified phenomenological models and the full composite Higgs machinery motivated from a 4D strongly coupled gauge theory. We present a Lagrangian at the TeV scale and identify a number of universal features, in particular regarding the spectra of the top-partners. Finally as a proof of principle we discuss the exotic decays of the top-partners in the SU(5)/SO(5) coset.

Speaker: Dr Avik Banerjee

top_partner_partikeldagarna_21.pdf

20 Svenska fysikersamfundets årsmöte 2022 i Lund

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.

Speaker: Peter Christiansen (Lund University (SE))

p_christiansen_SFS_2021.pdf

7:30 PM Conference dinner

Tuesday, November 23

Tuesday morning session 1: Reports from research, funding and outreach organisations

Convener: Christian Ohm

21 Report from VR

Speaker: Mathias Hamberg

2021-11-23 VR-RFI-CERN-Partikeldagarna-MH.pptx

22 Report from CERN

Speaker: Kerstin Jon-And

CERN_Partikeldagarna2021.pptx

23 Report from (R)ECFA

Speaker: David Anthony Milstead

RECFA-ECFA-upload.pdf

RECFA-ECFA-upload.pptx

24 Report from IPPOG

Speakers: Jonas Strandberg, Jonas Strandberg (KTH Royal Institute of Technology (SE))

IPPOGReport.pdf

25 Report from IUPAP

Speaker: Johan Rathsman

IUPAP-C4+C11_Rathsman.pdf

26 Report from ACCU

Speakers: Rebeca Gonzalez Suarez, Rebeca Gonzalez Suarez (Uppsala University (SE))

ACCU_PartikelDagarna2021.pdf

10:35 AM Coffee break

Tuesday morning session 2: Collaborative projects and national scientific groups reports

Other reports from collaborative research projects and national scientific groups may be shown elsewhere owing to speaker availability

Convener: David Marsh

27 Report from the Lund University ESSnuSB Group

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 flux measurement as well as measuring the interaction cross-section between nucleons and electron neutrinos. The Lund University ESSnuSB group is leading the development of the kiloton-scale water-Cherenkov component of the ND, including its reconstruction and particle identification performances. In this talk I will present the activity and latest results of the Lund University ESSnuSB group.

Speaker: Alexander Burgman (Lund University)

ABurgman_ESSnuSBND_211123_Partikeldagarna2021_v03.pdf

28 HIPPO — HIggs Pairs and POtential

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 boson with a mass of 125 GeV by ATLAS and CMS at the Large Hadron Collider (LHC) in 2012. The shape of the Higgs potential and the Higgs boson self-coupling are among the most important open questions in particle physics: establishing and measuring Higgs boson pair (HH) production is central to the LHC physics program, both as the experimental signature of the Higgs boson self-coupling and as a sensitive probe of several BSM scenarios. The Higgs boson self-coupling is also strongly related to cosmology and the aforementioned phase transition in the early Universe, which may have given rise to gravitational waves that appear as a background today. We are therefore at a historic junction, where a single measurement in the terrestrial LHC experiments can shed light on the early Universe and its behaviour as a whole. A dozen particle physicists in Sweden recently formed the HIPPO project to coherently tackle these questions. Via regular meetings, the corresponding research topics progress along two inter-connected tracks, one theoretical and one experimental, which exploit the interplay between directly probing the Higgs boson self-coupling and BSM physics at colliders and indirectly probing the phase transition in the early Universe through the gravitational-wave background. An application to the Wallenberg foundation is currently in preparation, aiming at injecting funding resources into the project and creating a world-leading research environment across four academic nodes in Lund, Stockholm and Uppsala.

Speaker: Arnaud Ferrari (Uppsala University (SE))

HIPPO.pdf

29 Status of the Light Dark Matter KAW project

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 new, highly sensitive experiment, LDMX, to discover such particles, over the development of software tools for simulations and statistical interpretation of the data, to connections and input to other existing and future experiments including direct detection. In this talk, we will review the motivation and goals of the project, report on recent activities and progress, and give an outlook on the next steps.

Speaker: Einar Alfred Elen

Status of the Light Dark Matter KAW Project.pdf

30 The SHIFT project

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 well as indirect searches via precision measurements of processes involving top quarks. In this talk we will present the project and its latest results.

Speaker: Sara Strandberg (Stockholm University (SE))

shift_partikeldagarna_211123.pdf

31 The Plasma Axion Haloscope and the ALPHA Collaboration

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 challenge due to the very small structures needed. Plasma haloscopes instead use a tunable plasma frequency to match the axion mass. Using a wire metamaterial plasma haloscope, the plasma frequency can be tuned to match the axion mass by changing the interwire spacing, allowing for large conversion volumes.

The newly formed ALPHA collaboration has begun work towards building a tunable, cryogenic, plasma haloscope. A wire metamaterial has been chosen as the target plasma, and is expected to reach competitive sensitivity for axion masses between 8$-$400$~\mu$eV. This talk will give an overview of the plasma haloscope concept and the ongoing experimental effort of the ALPHA collaboration.

Speaker: Katherine Dunne (Stockholm University (SE))

kdunne-alpha@SU-partikeldagarna2021.pdf

32 Report from the ATLAS groups on the ATLAS HL-LHC hardware work

Speaker: Jonas Steentoft

ATLAS_upgrade_PartikelDagarna-4.pdf

12:30 PM Lunch

Tuesday afternoon session 1: Diversity in physics

Convener: Caterina Doglioni

33 GENIE

Speaker: Pernilla Wittung Stafshede

34 NORNDIP

Speaker: Barbro Åsman

35 High-school project with open data

Speaker: Hans Jakobsson

Tuesday afternoon session 2: Election of a new board

Convener: Caterina Doglioni

3:00 PM Coffee break

Tuesday afternoon session 3: Astroparticle physics (theory and experiment)

Convener: Riccardo Catena

36 TeV halos and inhibited diffusion around pulsars

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 models of acceleration of charged particles by astrophysical sources like supernova remnants (SNRs) or Pulsar Wind Nebulae (PWN).
The goal of this talk is to overview what is this new class of object and the different theories able to explain the mechanisms leading to its formation and evolution. Finally, we will show the importance of the detection of these sources for our current understanding on galaxy evolution.

Speaker: Pedro Jose De La Torre Luque

Partikeldagarna-DeLaTorreLuque.pptx

37 No sharp spectral features in the local cosmic-ray positron flux

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 extremely smooth. Recently, however, observations have shown that the positron production of pulsars might be more complex than previously assumed. In this work, we take into account several mechanisms that greatly reduce the sharp spectral features in the positron flux predicted by the simple models, and create a pulsar model that is consistent with the smooth positron flux.

Speaker: Isabelle John (Stockholm University)

Partikeldagarna2021.pdf

38 Constraining dark matter annihilation with cosmic-ray antiprotons using neural networks

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. Importance sampling is identified as particularly suitable for efficiently marginalizing over the nuisance parameters related to cosmic-ray propagation while ensuring that the networks are only evaluated in well-trained parameter regions. The method allows to investigate a wide range of dark matter models and it speeds up the runtime by at least two orders of magnitude compared to conventional approaches. I will illustrate our method on two examples: First, for a generic dark matter model annihilating into a pair of $b\bar b$-quarks and and, second, for the scalar singlet dark matter model.

Speaker: Michael Korsmeier (Stockholm University and OKC)

Partikeldagarna2021_Korsmeier_public.pdf

39 Searching for axion-like particles through the photon disappearance channel

Axions and axion-like particles (ALPs) comprise theoretically well-motivated extensions of the Standard Model. ALPs can be naturally light, very weakly interacting, and may interconvert with photons in magnetic fields. I will discuss efforts over the past several years that leverage precision observations of X-ray emission from active galactic nuclei in galaxy clusters to search for signals from ALPs through the ‟photon disappearance channel”. These searches have led to world-leading limits on light ALPs, and can be further improved over the coming decade through the launch of the next generation of X-ray telescopes. I will briefly discuss new theoretical results that draw on elementary properties of quantum perturbation theory and Fourier analysis to drastically simplify the analysis of weak axion-photon mixing, leading to new conceptual insights and more robust phenomenology.

Speaker: David Marsh

Marsh_Partikeldagarna.pdf

40 Dark matter electron interactions in graphene detectors

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 non-relativistic effective field theory methods, whereas the physics of the graphene sheet is treated with state-of-the-art DFT.

Speaker: Einar Urdshals

Partikeldagarna_Urdshals.pdf

41 Can inelastic dark matter save DAMA?

Speaker: Sunniva Jacobsen

Partikeldagarna_2311.pptx

42 Probing the neutrino sky with IceCube: latest results

IceCube is the world's largest neutrino observatory with a km$^3$ array of optical detectors located at the South Pole in Antarctica. In over a decade of observation, IceCube has exceedingly shaped our understanding of the astrophysical neutrino paradigm. With a near 100% duty cycle, IceCube is a vital tool not only for neutrino astronomy, but also for probing BSM physics, fundamental neutrino physics with the vast volumes of atmospheric neutrinos it collects, and cosmic ray physics with the IceTop surface array. In this talk, I will highlight the most recent physics results from IceCube. I will also provide an overview of the currently underway IceCube upgrade and the contribution of the Sweden group to this effort.

Speaker: Ankur Sharma

IC_Sweden_PD21_Ankur_231121_new.pdf

43 IceCube-Gen2: The Window to the Extreme Universe

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 range by three orders of magnitude. The radio technique is a cost-effective way to instrument the huge volumes needed for the detection of ultra-high energy neutrinos at the predicted flux levels. IceCube-Gen2 will play an essential role in shaping the new era of multi-messenger astronomy, fundamentally advancing our knowledge of the high-energy universe through the combination of neutrino, electromagnetic, and gravitational wave observations.
I will report on the status of the project and expected sensitivity. I will present the Radio Neutrino Observatory in Greenland (RNO-G) that is currently under construction and serves as a field test for Gen2 radio. I will highlight the areas of Swedish contribution: development of novel optical sensors, intelligent trigger system based on deep learning for the radio array, and wind generators for autonomous operation in harsh polar environments.

Speaker: Christian Glaser

glaser_partikeldagarna_2021.pdf

44 A model-independent analysis of neutrino flares detected in IceCube from X-ray selected blazars

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 ambient photon fields and cascade down to X-ray energies before escaping.
In this work, we test the time-dependent neutrino emission potential of 1000 X-ray bright blazars by performing an untriggered search for neutrino flares from their direction in 10 years of IceCube data. The best-fit flare parameters are obtained using an unbinned likelihood maximization, and the binomial test statistic is used to search for statistically significant emission from a sub-population of the sources.

Speaker: Ankur Sharma

multifare_xray_blazars_Ankur_PD21_231121.pdf

45 Constraining the neutrino flux from cosmic population of Gamma-ray Bursts

Speaker: Kunal Deoskar

Deoskar_Talk.pdf