Past research

PhD studies

From 2018 until 2022 I have been a PhD student in theoretical astroparticle physics at National Centre for Nuclear Research, Poland where I have worked with Prof. Dr. Hab. Leszek Roszkowski and Dr. Sebastian Trojanowski on the elusive nature of dark matter. My PhD thesis focused on phenomenological prospects of BSM models motivated by the dark matter problem sketched below.

Through multifaceted observations of the Universe, it has been established that for each atom of ordinary, shining matter, there are five other atoms that do not shine nor interact in any other way, with exception of the universal, weakest force - gravity. Understanding properties of such feebly interacting matter - and possibly detecting it - is one of the most profound mystery of modern physics.
In light of this, my scientific interests focus on novel strategies of looking for dark matter in experiments that are already taking data or which will be operating in the near future. At present, the only definite signature of dark matter comes from its gravitational interactions taking place on the galactic and larger scales. Therefore, it is imperative to probe dark matter by a diverse set of experimental methods that are complementary to each other - which is one of the main theme in my research.

PhD research highlights

Indirect searches for Weakly Interacting Massive Particles
One possibility of detecting dark matter (DM) is by looking for light, coming from DM annihilations taking place at the galactic center where large abundance of DM is expected. We studied detection prospects of well-motivated DM candidate - supersymmetric neutralino - in Cherenkov Telescope Array (CTA) - the next generation gamma-ray observatory [1]. We found excellent perspectives for CTA to either detect thermally produced neutralino or, otherwise, severely constraint it.

Fig. 1: Projected CTA sensitivity to neutralino is denoted by thick dot-dashed line and covers important theoretical benchmark - thermal WIMP annihilation cross section (thin dotted line). Color coding of the points denotes the composition of the neutralinos and is critical in, e.g., Sommerfeld enhancement effect - one can see especially pronounced resonant peak at m~2.2 TeV for wino DM (blue points).

Fig. 2: Color-filled contours correspond to the contribution of secondary production to the sensitivities of FASER, SHiP and MATHUSLA detectors. The reach is extended to short lifetime regime, covering both the (g-2)μ and the relic density areas.

Intensity frontier searches for long lived particles
Large Hadron Collider discovered the Higgs boson in 2012 by making use of detectors looking for heavy, TeV-scale particles which are produced with weak-scale strength interactions. On the other hand, most of the states produced in proton proton collisions actually travel parallel to the beamline and escape large, but short detectors, like ATLAS and CMS. To take advantage of such "wasted” flux, several essentially zero-background experiments has been proposed like FASER, MATHUSLA, CODEX-b, MoeDAL, among others. Part of their physics program is dedicated to looking for new, light long lived particles. We studied secondary production of such state taking place by scattering with material located right in front of the detector [2]. We showed that such mechanism can significantly extend the sensitivity of the aforementioned detectors to shorter lifetime regime.

Non-standard neutrino interactions

We extended the secondary production mechanism to models with extended neutrino sector [3]. We studied dark neutrino portal and neutrino magnetic portal (shown in Fig. 4), among others, which are motivated by, e.g., various direct detection and neutrino experiments anomalies and neutrino mass generation. Once again, we found significant extension of parameter space coverage thanks to the secondary production. In addition to the displaced vertex signature (which is responsible for the reach shown in Fig. 2) we also studied scattering signatures taking place in the emulsion cloud chamber (ECC) detector at FASER2nu.

Fig. 3: FASER2nu sensitivity to neutrino magnetic portal due to secondary production. Green line at the bottom corresponds to displaced vertex signature, yellow line denotes scattering with electrons at the ECC while red bottom line represents secondary production followed by decay at the ECC. FASER2nu is the proposed extension to already working FASER experiment.

Fig. 4: Points shown lead to the strength of self-interaction that are preferred as a solution to small scale problems of ΛCDM. The points that also partly relieve Hubble tension are denoted by dark green shade; light green shows best fit.

Self-interacting dark matter and the Hubble tension

Standard model of cosmology, ΛCDM, incorporates dark matter as a noninteracting cold matter which leads to successful description of the Universe, especially at the large scales. However, at smaller scales severe discrepancies between theoretical predictions and observations were observed. One of the most promising solutions to that problem is to introduce velocity dependent interactions within the dark sector - the so-called self-interacting dark matter (SIDM). Moreover, recent observations identified another inconsistency within ΛCDM - the value of the Hubble rate parameter inferred from the late Universe was found to be significantly larger that the one obtained from the early Universe. In light of this, we proposed SIDM production mechanism taking place by late decays of pseudo-WIMP state which could relieve both of the aforementioned problems [4].

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