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@PHDTHESIS{Frerick:615582,
      author       = {Frerick, Jonas},
      othercontributors = {Schmidt-Hoberg, Kai and Brueggen, Marcus},
      title        = {{C}atching {D}ark {P}hotons in the {S}ky: {L}ooking for
                      light vector particles using satellites},
      school       = {Universität Hamburg},
      type         = {Dissertation},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron DESY},
      reportid     = {PUBDB-2024-06189, DESY-THESIS-2024-015},
      series       = {DESY-THESIS},
      pages        = {161},
      year         = {2024},
      note         = {Dissertation, Universität Hamburg, 2024},
      abstract     = {The lack of signals in traditional dark matter (DM)
                      searches beyond gravitational interactions provide an
                      excellent reason to investigate weakly coupled and/or light
                      dark sectors(DS). These receive motivation both from the
                      theoretical and the phenomenological side with rich physics
                      across many different scales. Depending on the exact
                      composition of the DS the signals can show up at colliders,
                      in astrophysical searches, and in specialised direct
                      detection experiments, which differ significantly from
                      traditional nuclear recoil searches. Furthermore, the low
                      mass of these new particles opens up new opportunities for
                      producing new physics in the lab beyond the typical
                      high-energy accelerators required for detecting new heavy
                      states. This thesis will focus specifically on a broad class
                      of DSs, namely those containing a Dark Photon (DP) in the
                      particle spectrum. The DP is a well-motivated candidate
                      which can act as a mediator between the standard model (SM)
                      and the DS but it is also knownto provide a rich
                      phenomenology by itself.This ranges from the oblique
                      corrections to electroweak precision observables (EWPO) at
                      high DP masses to the subtle impact of a light DP on
                      electromagnetism (EM). This thesis will provide an
                      introduction to the conventional coupling of the DP to the
                      full electroweak theory via the so-called kinetic mixing.We
                      will further discuss potential generalisations of this
                      mixing, i.e.via the Z boson mass or the Stückelberg
                      mechanism. We will show how a light DP decouples from
                      observables at colliders and that the kinetic mixing to
                      electromagnetism is the low-energy theory emerging from the
                      mixing with the hypercharge boson. This mixing with the
                      photon enables non-trivial effects of the DP in an SM
                      plasma. We will use the well-known plasma effects to
                      calculate the solar DP flux emerging from the plasma of
                      solar electrons. In contrast to the majority of the
                      literature, we will focus on the angular distribution of the
                      solar DP flux and point out the advantage of applying thisa
                      dditional information to helioscope searches for DPs. Using
                      data from Hinode XRT, a solar x-ray telescope, we
                      demonstrate that the sensitivity boost can be significant.
                      This observation is interesting in light of future
                      helioscopes, which is briefly discussed in this thesis as
                      well. The second part of this thesis will then be focussing
                      on the dark matter puzzle and the potential role of the DP
                      as a DM candidate. After providing a brief introduction to
                      the topic, we consider the LISA Pathfinder (LPF) mission as
                      a direct detection experiment for ultralight DPDM. In the
                      spirit of a no-go theorem, we provide reasons why the direct
                      detection of kinetically mixed DPs using LPF is impossible.
                      This result is also valid for other direct detection setups
                      with only a few caveats. However, we demonstrate that LPF is
                      an interesting instrument for investigating the signal of
                      general DPs, i.e. DPs gauged under global SM symmetries such
                      as B − L . We point out that the auxiliary channels of LPF
                      provide a powerful tool to look for the DM signal,
                      emphasising why it is expected to be better than the main
                      channel. In addition, potential follow-up projects are
                      discussed.},
      cin          = {T},
      cid          = {I:(DE-H253)T-20120731},
      pnm          = {611 - Fundamental Particles and Forces (POF4-611) / PHGS,
                      VH-GS-500 - PIER Helmholtz Graduate School
                      $(2015_IFV-VH-GS-500)$},
      pid          = {G:(DE-HGF)POF4-611 / $G:(DE-HGF)2015_IFV-VH-GS-500$},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:gbv:18-ediss-121307},
      doi          = {10.3204/PUBDB-2024-06189},
      url          = {https://bib-pubdb1.desy.de/record/615582},
}