Carl Niblaeus


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Arbetar vid Fysikum
Besöksadress Roslagstullsbacken 21 A, plan 5
Rum A5:1054
Postadress Stockholms universitet, Fysikum 106 91 Stockholm

Om mig

Jag är doktorand i CoPS-gruppen på Fysikum.

Jag är också aktiv i Fysikums doktorandråd och representerar doktoranderna i diverse kommittéer och nämnder.


Jag undervisar som lärarassistent i diverse kurser på fysikprogrammet.


Jag forskar inom teoretisk partikelfysik. Mer specifikt arbetar jag med fenomenologin för mörk materia, i huvudsak med hjälp av programmet DarkSUSY (


I urval från Stockholms universitets publikationsdatabas
  • 2017. Joakim Edsjö (et al.). Journal of Cosmology and Astroparticle Physics (6)

    Cosmic rays hitting the solar atmosphere generate neutrinos that interact and oscillate in the Sun and oscillate on the way to Earth. These neutrinos could potentially be detected with neutrino telescopes and will be a background for searches for neutrinos from dark matter annihilation in the Sun. We calculate the flux of neutrinos from these cosmic ray interactions in the Sun and also investigate the interactions near a detector on Earth that give rise to muons. We compare this background with both regular Earth-atmospheric neutrinos and signals from dark matter annihilation in the Sun. Our calculation is performed with an event-based Monte Carlo approach that should be suitable as a simulation tool for experimental collaborations. Our program package is released publicly along with this paper.

  • 2016. E. Perotti, Carl Niblaeus, S. Leupold. Nuclear Physics A 950, 29-63

    This work constitutes one part of an investigation of the low-temperature changes of the properties of the eta ' meson. In turn these properties are strongly tied to the U(1)(A) anomaly of Quantum Chromodynamics. The final aim is to explore the interplay of the chiral anomaly and in-medium effects. We determine the lifetime of an eta ' meson being at rest in a strongly interacting medium as a function of the temperature. To have a formally well-defined low-energy limit we use in a first step Chiral Perturbation Theory for a large number of colors. We determine the pertinent scattering amplitudes in leading and next-to-leading order. In a second step we include resonances that appear in the same mass range as the eta ' meson. The resonances are introduced such that the low-energy limit remains unchanged and that they saturate the corresponding low-energy constants. This requirement fixes all coupling constants. We find that the width of the eta ' meson is significantly increased from about 200 keV in vacuum to about 10 MeV at a temperature of 120 MeV.

  • 2017. Carl Niblaeus, Joakim Edsjö, Chad Finley.

    In the paper attached to this thesis, Paper I, we have calculated the flux of neutrinos that emanate from cosmic ray collisions in the solar atmosphere. These neutrinos are created in the cascades that follow the primary collision and can travel from their production point to a detector on Earth, interacting with the solar material and oscillating on the way. The motivation is both a better understanding of the cosmic ray interactions in the solar environment but also the fact that this neutrino flux presents an almost irreducible background for the searches for neutrinos from annihilations between dark matter particles in the Sun’s core.

    This interesting connection between neutrinos and dark matter make use of the Sun as a laboratory to investigate new models of particle physics. If dark matter consists of weakly interacting massive particles (WIMPs), the Sun will sweep up some of these WIMPs when it moves through the halo of dark matter that our galaxy lies in. These WIMPs will become gravitationally bound to the Sun and over time accumulate in the Sun’s core. In most models WIMPs can annihilate to Standard Model particles when encountering each other. The only particle that can make it out of the Sun without being absorbed is the neutrino. The buildup of WIMPs in the solar interior can therefore lead to a detectable flux of neutrinos.

    Neutrino telescopes therefore search for an excess of neutrinos from the Sun. To be able to ensure that a detected flux is in fact coming from dark matter annihilations one must properly account for all other sources of neutrinos. At higher energies these are primarily neutrinos created in energetic collisions between cosmic rays and particles in the Earth’s atmosphere, but also the solar atmospheric neutrinos. The latter will be tougher to disentangle from a WIMP signal since they also come from the Sun.

    We calculate in Paper I the creation of the neutrinos in the solar atmosphere and propagate these neutrinos to a detector on Earth, including oscillations and interactions in the Sun and vacuum oscillations between the Sun and the Earth. We find that the expected flux is small but potentially detectable by current neutrino telescopes, although further studies are needed to fully ascertain the possibility of discovery as well as how to properly disentangle this from a potential WIMP-induced neutrino signal. 

Visa alla publikationer av Carl Niblaeus vid Stockholms universitet

Senast uppdaterad: 8 november 2018

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