# Partikeldagarna 2019

Europe/Stockholm

### Planck, Fysikhuset

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Description

Partikeldagarna 2019 will be held at Linköping University on October 2-3 2019, in close connection with Fysikdagarna 2019 happening on October 3-5. The workshop is organized by the Particle and Astroparticle Physics Section of the Swedish Physical Society (Fysikersamfundet). The workshop starts on Wednesday at 10 am (registration with coffee) and ends on Thursday at 6 pm (the social dinner of Fysikdagarna is this evening, included in the fee). In addition, an optional social dinner specifically for the participants of Partikeldagarna will be organized on Wednesday evening.

The aim of the meeting is to have a status report and a professional discussion of current particle and astroparticle physics research in Sweden. Partikeldagarna 2019 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 organizations where Sweden is represented.

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

• Yasmine Amhis on CP violation;
• Stefano Vercellone on high-energy gamma-ray astronomy.

Registration: two steps! (please indicate any food restrictions/preferences in both forms)

• Everyone should register to Fysikdagarna (through this form), but NOT PAY!
• Also register separately for Partikeldagarna here in Indico.

Abstract submission: from July 1st to September 5th at noon.

In order to submit an abstract and register, you will have to use a CERN indico account. Contact the organizers for support, if needed.

Payment: 900 SEK for meeting (including light lunch on October 2nd, dinner on October 3rd, and all coffee breaks) and 600 SEK for the social dinner of October 2nd. In other words, the dinner for Partikeldagarna (Wednesday) is optional, and the social dinner for Fysikdagarna (Thursday) is included in the fee.

Accommodation: see separate accommodation tab.

Room: Planck, Fysikhuset

Organizers: Riccardo Catena (Chalmers), Arnaud Ferrari (Uppsala), Christian Ohm (KTH)

Videoconference Rooms
Partikeldagarna2019
Name
Partikeldagarna2019
Description
Yearly meeting of the Elementary Particle and Astroparticle Physics section of the Swedish Physical Society.
Extension
10813935
Owner
Christian Ohm
Auto-join URL
Phone numbers
Participants
• Alice Ohlson
• Allan Hallgren
• Andrew Lifson
• Arnaud Ferrari
• Bengt Lund-Jensen
• Bernhard Meirose
• catena riccardo
• Caterina Doglioni
• Christian Ohm
• Einar Alfred Elen
• Eleni Myrto Asimakopoulou
• Else Lytken
• Eric Edward Corrigan
• Erin O'Sullivan
• Eva Brottmann Hansen
• Felix Tellander
• Geoffrey Mullier
• Giulia Ripellino
• Jannik Geisen
• Johan Bijnens
• Johan Rathsman
• Jonas Strandberg
• Karl Filip Backman
• Katherine Dunne
• Kerstin Jon-And
• Klas Hultqvist
• Kunal Deoskar
• Laura Barranco Navarro
• Laura Pereira Sanchez
• Malin Sjodahl
• Marcus Pernow
• Matti Jansson
• Mattias Blennow
• Mattias Sjö
• Michael Nelson
• Mohanraj Senniappan
• Olga Botner
• Pablo Fernández de Salas
• Patrawan (Prim) Pasuwan
• Rabia shaheen
• Rebeca Gonzalez Suarez
• Richard Brenner
• Richard Jacobsson
• Rikkert Frederix
• Ruth Pottgen
• Sara Strandberg
• Stefano Moretti
• Stefano Vercellone
• Stefio Yosse Andrean
• Sten Hellman
• Thomas Mathisen
• Timea Vitos
• Timon Emken
• Tomas Bylund
• Torbjörn Lundberg
• Tord Ekelöf
• Venugopal Ellajosyula
• Yasmine Sara Amhis
• Yvonne Becherini
• Wednesday, 2 October
• 10:00 10:20
Registration with coffee 20m Planck, Fysikhuset

### Planck, Fysikhuset

• 10:20 13:00
Wed morning session: MAX IV & Astroparticle physics, including neutrinos and Dark Matter Planck, Fysikhuset

### Planck, Fysikhuset

Convener: Caterina Doglioni (Lund University (SE))
• 10:20
MAX IV Status (15+5) 20m
Speaker: Bernhard Meirose (Lund University)
• 10:40
Direct detection of low-mass dark matter with strong matter interactions -- 15+5 20m
Speaker: Dr Timon Emken (Chalmers University of Technology)
• 11:00
Measuring the local dark matter density at direct detection experiments -- 15+5 20m
Speakers: Riccardo Catena (Chalmers University of Technology), Riccardo Catena (Chalmers University of Technology)
• 11:20
Local dark matter density from the Milky Way's rotation curve using Gaia DR2 data -- 15+5 20m
Speaker: Pablo Fernández de Salas (Stockholm University)
• 11:40
Update on the Neutrino Observatory in ice with radio technique -- 15+5 20m
Speaker: Prof. Allan Hallgren (Uppsala University)
• 12:00
Results from IceCube and the path to the Upgrade and Gen2 -- 15+5 20m
• 12:20
The Hyper-Kamiokande Experiment -- 15+5 20m
Speakers: Dr Erin O'Sullivan (Stockholm University), Erin O'Sullivan (Queen's University), Erin O'Sullivan (Uppsala University )
• 12:40
ESSnuSB: physics reach and instrumentation development -- 15+5 20m
Speaker: Mattias Blennow (KTH Royal Institute of Technology)
• 13:00 14:00
Lunch 1h Planck, Fysikhuset

### Planck, Fysikhuset

• 14:00 16:00
Wed afternoon session 1: Reports from research and funding organizations Planck, Fysikhuset

### Planck, Fysikhuset

Convener: Arnaud Ferrari (Uppsala University (SE))
• 14:00
VR+RFI (12+3) 15m
Speaker: Mathias Hamberg (Swedish Research Council)
• 14:15
CERN Council including update of the European strategy for particle physics (15+5) 20m
Speaker: Kerstin Jon-And (Stockholm University (SE))
• 14:35
(R)ECFA (12+3) 15m
Speaker: David Anthony Milstead (Stockholm University (SE))
• 14:50
IPPOG (12+3) 15m
Speaker: Jonas Strandberg (KTH Royal Institute of Technology (SE))
• 15:05
High-school project with open data (8+2) 10m
Speaker: Mariam Khodaverdian (KTH)
• 15:15
IUPAP (12+3) 15m
Speaker: Johan Rathsman
• 15:30
ACCU (12+3) 15m
Speaker: Sara Strandberg (Stockholm University (SE))
• 15:45
Election of a new board (15) 15m
Speakers: Johan Rathsman, Sara Strandberg (Stockholm University (SE))
• 16:00 16:20
Coffee break 20m Planck, Fysikhuset

### Planck, Fysikhuset

• 16:20 18:20
Wed afternoon session 2: LHC experiments: ATLAS+ALICE Planck, Fysikhuset

### Planck, Fysikhuset

• 16:20
ATLAS detector operation, data-quality and physics object performance (15+5) 20m
Speaker: Laura Pereira Sanchez (Stockholm University (SE))
• 16:40
Speaker: Geoffrey Mullier (Lund University (SE))
• 17:00
Higgs physics in ATLAS (15+5) 20m
Speaker: Michael Edward Nelson (Stockholm University (SE))
• 17:40
Other BSM physics in ATLAS (15+5) 20m
Speaker: Eva Brottmann Hansen (Lund University (SE))
• 18:00
ALICE (15+5) 20m
Speaker: Alice Ohlson (Lund University (SE))
• Thursday, 3 October
• 09:00 10:10
Thu morning session 1: Student talks Planck, Fysikhuset

### Planck, Fysikhuset

Convener: Riccardo Catena (Chalmers University of Technology)
• 09:00
Blazars as astroparticle physics laboratories: the case of KUV00311-1938 (11+3) 14m

Blazars are very bright gamma ray sources in the sky that are visible out to very large redshifts. Powered by material falling into a supermassive black hole, blazars have jets that can emit gamma rays up to TeV energies. As these TeV photons propagate through space they are expected to encounter ambient magnetic fields and extragalactic background light (EBL). The presence of magnetic fields can convert them to Axion like particles (ALPs), while the presence of the EBL absorbs the initial spectrum via pair production. We studied the multi-wavelength behaviour of KUV 00311-1938, a blazar with an unknown redshift, finding that a simple EBL model can explain the observed emission. We subsequently used the EBL model to constrain the redshift of the source.

Speaker: Tomas Bylund
• 09:14
Observing the sky continuously at extreme photon energies with ALTO/COMET (11+3) 14m

ALTO is a future very-high-energy (VHE) gamma-ray observatory, which is currently in the prototyping phase. The proposed design of the array consists of more than a thousand Water Cherenkov Detectors (WCDs) each coupled with a liquid scintillator. The observatory will be installed at an altitude of 4 to 5 km above the sea level in the Southern Hemisphere. WCDs sample the secondary particles in the extensive air showers generated by VHE gamma-rays and cosmic rays while the scintillators help in tagging the presence of muons. Preliminary studies using the simulation shows that the scintillators help in improving the signal over background discrimination by 15 to 30% depending on the energy range. The first phase of the prototype, comprised of two WCDs and scintillators, has been taking data since February 2019. In the poster, I will present the simulation performance and some results from the prototype activities. Finally I will also present the future steps of the project.

Speaker: Mohanraj Senniappan (Linnaeus University)
• 09:28
Anomaly-free model building: algebraic geometry and the Froggatt-Nielsen mechanism (11+3) 14m

We present methods to find anomaly-free gauged U(1) Froggatt-Nielsen type models using results from real algebraic geometry. These methods should be of general interest for model building beyond the Standard Model when rational charges are required. We consider models with a gauged U(1) flavour symmetry with one flavon and provide several model examples based on different physical assumptions. Necessary conditions for these models to be free from gauge anomalies are derived and we show that the field content of the Standard Model is not sufficient and thus additional fields are needed. Two such extensions are considered; two Higgs doublets and right-handed neutrinos providing Dirac masses. With these extensions, the fermion masses and mixings in the Standard Model, including neutrinos, can in great part be explained.
Moreover, we show that the UV-behaviour of these models are in general plagued by Landau poles. Two different UV-completions are considered; through vector-like fermions and through Higgs doublets. In the fermion completion, the gauge couplings are in general plagued with Landau poles while in a scalar completion this may be avoided, but instead the quartic couplings generally blow up. Thus, the generic case is that neither completion works, but the scalar completion might be saved by appropriate choice of parameters in the scalar potential. This conclusion does not change if we allow U(1) to be anomalous or global.

Speaker: Felix Tellander (Lund University)
• 09:42
Finite temperature effects on particle decays (11+3) 14m

At high densities and temperatures the standard quantum field theoretical approach to particle physics should be modified. Temperature enters explicitly in observables, for instance in decay rates, and under certain conditions expected results deviate significantly from the case of zero-temperature. I have put together a collection of thermal decay rates covering scalars, pseudo scalars and fermions consequently expanding the existing literature. I aim to lay out the procedure of thermal calculations detailing the explicit appearance of temperature in the two-point correlation function. I also highlight the interpretation of the thermal decay rate in comparison with the zero-temperature dito.

Speaker: Mr Torbjörn Lundberg (Lund University)
• 09:56
The helicity-flow method (11+3) 14m

It is well-known that the spinor-helicity method can significantly simplify the calculations of both Feynman diagrams and scattering amplitudes. In this work, we attempt to further simplify the Feynman-diagram calculation by converting the spinor-helicity method into a flow method, analogous to allowing a one-line journey from Feynman diagram to inner products. The cases of massless QED and QCD will be discussed.

Speaker: Andrew Lifson (Lund University)
• 10:10 10:30
Coffee break 20m Planck, Fysikhuset

### Planck, Fysikhuset

• 10:30 11:00
Thu morning session 2: Poster teaser talks Planck, Fysikhuset

### Planck, Fysikhuset

Convener: Yvonne Becherini (Linnaeus University)
• 10:30
IceCube search for neutrinos from precursors and afterglows of gamma ray bursts 3m

The sources and accelerating mechanisms of cosmic rays, with energies as high as 10^{20} eV, are not completely understood. Gamma ray bursts (GRBs) have long been considered as promising source candidates, yet so far don't show evidence for a correlated neutrino signal to prove this hypothesis. Previous analyses by IceCube have searched for neutrino in coincidence with the prompt phase of the GRBs, typically lasting for 100s or less. Here I will describe a search for neutrino correlations before and after this prompt phase using an extended time window. Presently I am calculating the spatial and temporal coincidence of a list of GRBs with the neutrino detections made by IceCube and comparing the results for different precursor and afterglow models hypothesised for short and long duration GRBs. These searches build on a similar methodology as was used for the detection of longer time-scale transients such as blazar flares, applying it for the first time to short transients like GRBs.

Speaker: Kunal Deoskar (Stockholm University)
• 10:33
Searches for dark matter mediators decaying to jets in ATLAS 3m

An important part of the ATLAS dark matter (DM) search programme is comprised of searches for new resonances (dark matter mediators) decaying to hadronic final states. This talk will give an overview of one such analysis: the recently-published search for low-mass dark-matter mediators decaying to jets, with an associated high-pT photon. This search triggers on an associated photon in order to significantly extend the sensitive region of ATLAS for dark matter mediators and generic resonances. Also covered is the reinterpretation of the resulting limits in the case of non-discovery.

Speaker: Eric Edward Corrigan (Lund University (SE))
• 10:36
Exploring selections across channels in Dark Matter searches with top quarks at the ATLAS experiment of the LHC 3m

Current estimates put Dark Matter to 26.8% of the energy-matter content of the universe, but very little is known about it other than its gravitational interactions. Efforts to learn more about Dark Matter include searching for it at high energy particle colliders. The lack of information about the nature of Dark Matter makes this a complicated task, and many searches are performed in different channels, and considering different theoretical models. In my master thesis, I explore two such analyses, performed in the ATLAS collaboration using data from the ATLAS detector at the Large Hadron Collider at CERN: the tW+MET final state and the tt̄+MET final state. I have made a generation-level study of the overlap between the signal regions used, and come to the conclusion that there is some. I have also compared the models used in these analyses, the 2HDM+a and the simplified spin-0 pseudoscalar model.Given the simplifications made in my study, however, more sophisticated approaches should be used before anything conclusive can be said.

Speaker: Olga Sunneborn Gudnadottir (Uppsala University (SE))
• 10:39
Unfolding of multivariate tools and statistical analysis for Higgs boson pair production searches in the ATLAS detector at the Large Hadron Collider 3m

Recently, searches for pair production of Higgs bosons in several final states have been carried out by the ATLAS exeperiment at the Large Hadron Collider (LHC). This study focuses on the search for non-resonant di-Higgs production decaying to a final state with two $b$-jets and two $\tau$-leptons using 36.1 fb$^{-1}$ of data recorded by the ATLAS detector. The analysis for this process has already been performed. Boosted decision trees (BDTs) are used in the analysis to improve the separation of the signal from background processes and several variables that provide good discrimination between signal and background are used as inputs to the BDT. This study aims to unfold the BDT of the analysis and optimize a cut-based analysis so that the gain from using the BDT can be estimated. Two variables, related to the invariant masses and angular distances of the Higgs boson decay products, are defined and the optimal cuts are found to be $X_{m_{\tau\tau}m_{bb}}>1.8$ and $X_{\Delta R_{\tau\tau}\Delta R_{bb}} >4.0$. Then, the upper limits on the SM $HH$ production cross section are set when fitting $m_{HH}$ with the cut-based analysis. An expected limit of 0.78 pb, 23 times the SM prediction is obtained when neglecting systematic uncertainties, compared to the limit of 15 times the SM as recomputed when using the BDT. Comparing the two results, the sensitivity is worsened by 50% when not using the BDT.

• 10:42
Non-Standard Decays of Vector-Like Quarks 3m

With strong constraints on the mass of vector-like quarks (VLQ) from the top partner (T) decay T->SM, it is necessary to consider non-standard decays of such partners. This talk considers models where the VLQ decays to a BSM (pseudo)scalar (S) and a top-quark. The scalar is assumed to be fermiophobic, and dominantly decays into two SM bosons. With dedicated analyses, we realistically quantify the sensitivity of the LHC to both the T and S masses, assuming both current and foreseen luminosities.

Speaker: Thomas Mathisen (Uppsala University (SE))
• 10:45
Impact of different compilers and build types on Geant4 simulation execution time 3m

Experimental observations and advanced computer simulations in High Energy Physics (HEP) paved way for the recent discoveries at the Large Hadron Collider (LHC) at CERN. Currently, Monte Carlo simulations account for a very significant amount of computational resources of the Worldwide LHC Computing Grid (WLCG).

In looking at the recent trends in modern computer architectures we see a significant deficit in expected growth in performance. Coupled with the increasing compute demand for High Luminosity (HL-LHC) run, it becomes vital to address this shortfall with more efficient simulation.

The simulation software for particle tracking algorithms of the LHC experiments predominantly relies on the Geant4 simulation toolkit. The Geant4 framework can be built either as a dynamic or a static library, the former being the more widely used approach. This study focuses on evaluating the impact of both having libraries statically vs dynamically linked and compiler optimization levels, on the simulation software’s execution time.

Multiple versions of the more widely used versions of compilers for UNIX-like systems have been used for these investigations. Both compiler optimization levels (e.g. O3, O2 on GCC) and link-time optimization (LTO) have been studied. Initial results indicate that significant execution time reductions can be obtained by switching from static to dynamic linking.

Speaker: Einar Alfred Elen (Lund University (SE))
• 10:48
Synergies between different disciplines for the European Particle Physics Strategy Update 3m

One overarching objective of science is to further our understanding of the universe, from its early stages to its current state and future evolution. This depends on gaining insight on the universe’s most macroscopic components, for example galaxies and stars, as well as describing its smallest components, namely elementary particles and nuclei and their interactions. It is clear that this endeavor requires combined expertise from the fields of astroparticle physics, particle physics and nuclear physics. Pursuing common scientific drivers also require mastering challenges related to instrumentation (e.g. beams and detectors), data acquisition, selection and analysis, and making data and results available to the broader science communities. Joint work and recognition of these “foundational” topics will help all communities grow towards their individual and common scientific goals. This contribution presents the work that various communities and experiments are doing to solve one of the many common challenges faced by particle physics and astrophysics: the necessity of dealing with large, sometimes heterogeneous datasets and derive insight from them in short periods of time.

Speaker: Caterina Doglioni (Lund University (SE))
• 11:00 12:00
Plenary talk 1: CP-violation Planck, Fysikhuset

### Planck, Fysikhuset

• 11:00
CP violation 1h
Speaker: Yasmine Sara Amhis (Centre National de la Recherche Scientifique (FR))
• 12:00 13:00
Lunch 1h
• 13:00 15:00
Thu afternoon session 1: Physics days plenary talks
• 15:00 15:10
Short walk 10m
• 15:10 16:10
Plenary talk 2: High-energy gamma astronomy Planck, Fysikhuset

### Planck, Fysikhuset

• 15:10
High-energy gamma astronomy 1h
Speaker: Stefano Vercellone (National Institute for Astrophysics - INAF)
• 16:10 16:30
Coffee break 20m Planck, Fysikhuset

### Planck, Fysikhuset

• 16:30 17:30
Thu afternoon session 2: New initiatives and future projects Planck, Fysikhuset

### Planck, Fysikhuset

Convener: Christian Ohm (KTH Royal Institute of Technology (SE))
• 16:30
Physics opportunities with the CERN SPS Beam Dump Facility (15+5) 20m
Speaker: Richard Jacobsson (CERN)
• 16:50
The HIBEAM/NNBAR Experiment at the ESS (15+5) 20m
Speaker: David Anthony Milstead (Stockholm University (SE))
• 17:10
Prospects and Progress of the Light Dark Matter eXperiment (LDMX) -- 15+5 20m
Speaker: Ruth Pottgen (Lund University (SE))
• 17:30 19:00
Posters Just outside Planck