anastso

• Acharyya, A.; Adam, R.; Adams, C.; Agudo, I.; Aguirre-Santaella, A. & Alfaro, R. [Show all 450 contributors for this article] (2021). Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre. Journal of Cosmology and Astroparticle Physics (JCAP). 2021(1). doi: 10.1088/1475-7516/2021/01/057. Full text in Research Archive Show summary

  We provide an updated assessment of the power of the Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at the TeV scale, via the associated gamma-ray signal from pair-annihilating dark matter particles in the region around the Galactic centre. We find that CTA will open a new window of discovery potential, significantly extending the range of robustly testable models given a standard cuspy profile of the dark matter density distribution. Importantly, even for a cored profile, the projected sensitivity of CTA will be sufficient to probe various well-motivated models of thermally produced dark matter at the TeV scale. This is due to CTA's unprecedented sensitivity, angular and energy resolutions, and the planned observational strategy. The survey of the inner Galaxy will cover a much larger region than corresponding previous observational campaigns with imaging atmospheric Cherenkov telescopes. CTA will map with unprecedented precision the large-scale diffuse emission in high-energy gamma rays, constituting a background for dark matter searches for which we adopt state-of-the-art models based on current data. Throughout our analysis, we use up-to-date event reconstruction Monte Carlo tools developed by the CTA consortium, and pay special attention to quantifying the level of instrumental systematic uncertainties, as well as background template systematic errors, required to probe thermally produced dark matter at these energies.

• Abdalla, H.; Abe, H.; Acero, F.; Acharyya, A.; Adam, R. & Agudo, I. [Show all 499 contributors for this article] (2021). Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation. Journal of Cosmology and Astroparticle Physics (JCAP). 2021(2). doi: 10.1088/1475-7516/2021/02/048. Full text in Research Archive
• Bondarenko, Kyrylo; Boyarsky, Alexey; Bringmann, Torsten; Hufnagel, Marco; Schmidt-Hoberg, Kai & Sokolenko, Anastasia (2020). Direct detection and complementary constraints for sub-GeV dark matter. Journal of High Energy Physics (JHEP). ISSN 1126-6708. doi: 10.1007/JHEP03(2020)118. Full text in Research Archive
• Boiarska, Iryna; Bondarenko, Kyrylo; Boyarsky, Alexey; Ovchynnikov, Maksym; Ruchayskiy, Oleg & Sokolenko, Anastasia (2020). Light scalar production from Higgs bosons and FASER 2. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2020(5), p. 1–20. doi: 10.1007/JHEP05(2020)049. Full text in Research Archive Show summary

  The most general renormalizable interaction between the Higgs sector and a new gauge-singlet scalar S is governed by two interaction terms: cubic and quartic. The quartic term is only loosely constrained by invisible Higgs decays and given current experimental limits about 10% of all Higgs bosons at the LHC can be converted to new scalars with masses up to mHiggs/2. By including this production channel, one significantly extends the reach of the LHC-based Intensity Frontier experiments. We analyze the sensitivity of the FASER experiment to this model and discuss modest changes in the FASER 2 design that would allow exploring an order-of-magnitude wider part of the Higgs portal’s parameter space.

• Boiarska, Iryna; Bondarenko, Kyrylo; Boyarsky, Alexey; Gorkavenko, Volodymyr; Ovchynnikov, Maksym & Sokolenko, Anastasia (2019). Phenomenology of GeV-scale scalar portal. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2019:162(11), p. 1–45. doi: 10.1007/JHEP11(2019)162. Full text in Research Archive
• Bondarenko, Kyrylo; Boyarsky, Alexey; Bringmann, Torsten & Sokolenko, Anastasia (2018). Constraining self-interacting dark matter with scaling laws of observed halo surface densities. Journal of Cosmology and Astroparticle Physics (JCAP). 2018(4), p. 1–27. doi: 10.1088/1475-7516/2018/04/049. Full text in Research Archive Show summary

  The observed surface densities of dark matter halos are known to follow a simple scaling law, ranging from dwarf galaxies to galaxy clusters, with a weak dependence on their virial mass. Here we point out that this can not only be used to provide a method to determine the standard relation between halo mass and concentration, but also to use large samples of objects in order to place constraints on dark matter self-interactions that can be more robust than constraints derived from individual objects. We demonstrate our method by considering a sample of about 50 objects distributed across the whole halo mass range, and by modelling the effect of self-interactions in a way similar to what has been previously done in the literature. Using additional input from simulations then results in a constraint on the self-interaction cross section per unit dark matter mass of about σ/mχlesssim 0.3 cm2/g. We expect that these constraints can be significantly improved in the future, and made more robust, by i) an improved modelling of the effect of self-interactions, both theoretical and by comparison with simulations, ii) taking into account a larger sample of objects and iii) by reducing the currently still relatively large uncertainties that we conservatively assign to the surface densities of individual objects. The latter can be achieved in particular by using kinematic observations to directly constrain the average halo mass inside a given radius, rather than fitting the data to a pre-selected profile and then reconstruct the mass. For a velocity-independent cross-section, our current result is formally already somewhat smaller than the range 0.5−5 cm2/g that has been invoked to explain potential inconsistencies between small-scale observations and expectations in the standard collisionless cold dark matter paradigm.

• Sokolenko, Anastasia; Bondarenko, Kyrylo; Brinckmann, Thejs; Zavala, Jesús; Vogelsberger, Mark & Bringmann, Torsten [Show all 7 contributors for this article] (2018). Towards an improved model of self-interacting dark matter haloes. Journal of Cosmology and Astroparticle Physics (JCAP). 2018:039(12), p. 1–32. doi: 10.1088/1475-7516/2018/12/038. Full text in Research Archive Show summary

  We discuss the relation between the strength of the self-interaction ofdark matter particles and the predicted properties of the inner density distributionsof dark matter haloes. We present the results ofN-body simulations for 28 galaxycluster sized haloes performed with the same initial conditions for cold dark matterand for self-interacting dark matter with cross-sections ranging from 0.1 to 10 cm2/g.We provide a simple phenomenological description of these results and compare themto the semi-analytical model typically used in the literature. We find that some of theassumptions made in this model are not satisfied in the simulations. We identify thereasons for this disagreement and improve the semi-analytical model correspondingly.We discuss how simulation results can be properly compared with observations and inparticular how quantities like the core radius and the inner dark matter surface densitydepend on the self-interaction cross-section.

• Sokolenko, Anastasia; Bondarenko, Kyrylo; Boyarsky, Alexey & Shchutska, Lesya (2018). Connection between diphoton and triboson channels in new physics searches. Physics Letters B. ISSN 0370-2693. 787, p. 23–29. doi: 10.1016/j.physletb.2018.08.067. Full text in Research Archive Show summary

  Diphoton channel provides a clean signature in searches for new physics. In this paper, we discuss a connection between the diphoton channel (γγ ) and triboson channels (Zγγ , Z Zγ , W W γ ) imposed by the SU(2)L × U(1)Y symmetry of the Standard Model (SM) in certain classes of models. To illustrate this idea we choose a simple model that has all these channels. In this model, the same physics can give rise to γ + MET instead of γγ and 2 bosons plus missing energy instead of 3-boson channels. We analyze existing constraints and previous searches and show that channels W W γ and especially Zγ + MET have a potential to discover new physics at the LHC.

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• Sokolenko, Anastasia (2019). Enlightening the Dark. Universitetet i Oslo. Full text in Research Archive Show summary

  The Standard Model of particle physics is an extremely successful theory checked to very high precision. Its last prediction, the Higgs boson, was discovered in 2012. Yet we know now that it is not complete. The main reason to believe so is the observation of several phenomena that cannot be explained by the Standard Model: Neutrino masses, Dark Matter, Matter-antimatter asymmetry of the Universe. We concentrate on the problem of Dark Matter (DM), the other problems are used as a source of motivation for the models of DM. We present the evidence for the existence of DM, briefly describe what is known about possible properties of DM particle and give examples of candidates. We discuss in details the scenario of self-interacting DM and obtain robust constraints on this model. We analyze the sensitivity of new major instrument - Cherenkov Telescope Array - for astrophysical detection of DM annihilation. Finally, we consider an example of combinations of constraints coming from particle physics, cosmology, and astrophysics. We show that this combination allows excluding a significant part of the parameter space of future experiments that aim to detect DM directly.

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