Publications

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• A brief introduction to extended gravity and connections to dark energy: Illustrated with scalar field examples

  Clare Burrage

  SciPost Phys. Lect. Notes 41 (2022) · published 15 March 2022 | Toggle abstract · pdf

  These lecture notes provide a brief introduction to extensions of gravity and their connections to dark energy. Due to time and space limitations this is not a comprehensive review of the field. Instead, I aim to introduce key concepts and ideas in this area through a series of examples based on scalar field extensions of gravity and models of dark energy.

  1 citation

• Probing the Inflaton Potential with SKA

  Tanmoy Modak, Tilman Plehn, Lennart Röver, Björn Malte Schäfer

  SciPost Phys. Core 5, 037 (2022) · published 18 July 2022 | Toggle abstract · pdf

  SKA will be a major step forward not only in astrophysics, but also in precision cosmology. We show how the neutral hydrogen intensity map can be combined with the Planck measurements of the CMB power spectrum, to provide a precision test of the inflaton potential. For a conservative range of redshifts we find that SKA can significantly improve current constraints on the Hubble slow-roll parameters.

  1 citation

• Topological quantum computation using analog gravitational holonomy and time dilation

  Emil Génetay Johansen, Tapio Simula

  SciPost Phys. Core 6, 005 (2023) · published 1 February 2023 | Toggle abstract · pdf

  Non-universal topological quantum computation models, such as the Majorana fermion-based Ising anyon model, have to be supplemented with an additional non-topological noisy gate in order to achieve universality. Here we endeavour to remedy this using an Einstein­—Cartan analog gravity picture of scalar fields. Specifically, we show that the analog gravity picture enables unitary transformations to be realized in two distinct ways: (i) via space-time holonomy and (ii) as gravitational time dilation. The non-abelian geometric phases are enabled by gravitational interactions, which are mediated by the spin-connection. We analytically compute its matrix elements as a function of the scalar field density distribution. This density can be regarded as the gravitating distribution of matter in an analog universe. We show via explicit calculations that there exists an infinite set of asymptotically flat analog gravitational fields, each of which implements a unique unitary transformation, that render the interactions topological. We emphasise the generality of this result by asserting that such gravitational gates could potentially be implemented in a broad range of real systems modeled by scalar field with an acoustic metric.

  1 citation

• The double smeared null energy condition

  Jackson R. Fliss, Ben Freivogel, Eleni-Alexandra Kontou

  SciPost Phys. 14, 024 (2023) · published 27 February 2023 | Toggle abstract · pdf

  The null energy condition (NEC), an important assumption of the Penrose singularity theorem, is violated by quantum fields. The natural generalization of the NEC in quantum field theory, the renormalized null energy averaged over a finite null segment, is known to be unbounded from below. Here, we propose an alternative, the double smeared null energy condition (DSNEC), stating that the null energy smeared over two null directions has a finite lower bound. We rigorously derive DSNEC from general worldvolume bounds for free quantum fields in Minkowski spacetime. Our method allows for future systematic inclusion of curvature corrections. As a further application of the techniques we develop, we prove additional lower bounds on the expectation values of various operators such as conserved higher spin currents. DSNEC provides a natural starting point for proving singularity theorems in semi-classical gravity.

  1 citation

• Even lighter particle dark matter

  Alvaro E. Chavarria

  SciPost Phys. Proc. 12, 001 (2023) · published 3 July 2023 | Toggle abstract · pdf

  We report on recent progress in the search for dark matter particles with masses from 1 Mev to 1 Gev . Several dark matter candidates in this mass range are expected to generate measurable electronic-recoil signals in direct-detection experiments. We focus on dark matter particles scattering with electrons in semiconductor detectors since they have fundamentally the highest sensitivity due to their low ionization threshold. Charge-coupled device (CCD) silicon detectors are the leading technology, with significant progress expected in the coming years. We present the status of the CCD program and briefly report on other efforts.

  1 citation

• Axions in the early universe

  Francesco D'Eramo

  SciPost Phys. Proc. 12, 005 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The Peccei-Quinn solution to the strong CP problem provides a motivated framework rich in cosmological consequence. Thermal axion production is unavoidable if there is a thermal bath at early times. Scattering and decay processes of bath particles can dump relativistic axions in the primordial plasma, and they can leave observable signatures in cosmological observables probing both the early and the late universe if produced with a significant abundance. We present recent and significant improvements for the calculation of the axion production rate for different scenarios and apply these results to predict the abundance of produced axions. Finally, we provide updated cosmological bounds on the QCD axion mass.

  1 citation

• Sub-GeV dark matter searches with EDELWEISS: New results and prospects

  Hugues Lattaud on behalf of the EDELWEISS collaboration

  SciPost Phys. Proc. 12, 012 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The Edelweiss collaboration performs light Dark Matter (DM) particles searches with germanium bolometer collecting charge and phonon signals. Thanks to the Neganov-Trofimov-Luke (NTL) effect, a RMS resolution of 4.46 electron-hole pairs was obtained on a massive (200g) germanium detector instrumented with a NbSi Transition Edge Sensor (TES) operated underground at the Laboratoire Souterrain de Modane (LSM). This sensitivity made possible a search for WIMP using the Migdal effect down to 32 MeV/C$^{2}$ and exclude cross-sections down to 10$^{-29}$ cm$^2$. It is the first measurement in cryogenic germanium with such thermal sensor, proving the high relevance of this technology. Furthermore, such TES have shown sensitivity to out-of-equilibrium phonons, paving the way for EDELWEISS new experience CRYOSEL. This is an important step in the development of Ge detectors with improved performance in the context of the EDELWEISS-SubGeV program.

  1 citation

• Dark Matter: DAMA/LIBRA and its perspectives

  R. Bernabei, P. Belli, F. Cappella, V. Caracciolo, R. Cerulli, C.J. Dai, A. d'Angelo, A. Incicchitti, A. Leoncini, X.H. Ma, V. Merlo, F. Montecchia, X.D. Sheng, Z.P. Ye

  SciPost Phys. Proc. 12, 025 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The long-standing model-independent annual modulation effect measured by DAMA deep underground at Gran Sasso Laboratory with different experimental configurations is summarized and perspectives will be highlighted. DAMA/LIBRA-phase2 set-up, $\simeq$ 250 kg highly radio-pure NaI(Tl) confirms the evidence of a signal that meets all the requirements of the model independent Dark Matter annual modulation signature at high C.L.; the full exposure is 2.86 ton $\times$ yr over 22 annual cycles. The experiment is currently collecting data in the DAMA/LIBRA-phase2 empowered configuration with an even lower software energy threshold. Other recent claims are shortly commented.

  1 citation

• Attenuation of cosmic-ray up-scattered dark matter

  Helena Kolesova

  SciPost Phys. Proc. 12, 055 (2023) · published 5 July 2023 | Toggle abstract · pdf

  GeV-scale dark matter particles with strong coupling to baryons evade the standard direct detection limits as they are efficiently stopped in the overburden and, consequently, are not able to reach the underground detectors. On the other hand, it has been shown that it is possible to probe this parameter space taking into account the flux of dark matter particles boosted by interactions with cosmic rays. We revisit these bounds paying particular attention to interactions of the relativistic dark matter particles in the Earth's crust. The effects of nuclear form factors, inelastic scattering and extra dependence of the cross section on transferred momentum (e.g. due to presence of light mediators) are studied and are found to be crucial for answering the question as to whether the window for GeV-scale strongly interacting dark matter is closed or not.

  1 citation

• Testing the mean field theory of scalar field dark matter

  Andrew Eberhardt, Alvaro Zamora, Michael Kopp, Tom Abel

  SciPost Phys. Proc. 12, 058 (2023) · published 5 July 2023 | Toggle abstract · pdf

  Scalar field dark matter offers an interesting alternative to the traditional WIMP dark matter picture. Astrophysical and cosmological simulations are useful to constraining the mass of the dark matter particle in this model. This is particularly true at low mass where the wavelike nature of the dark matter particle manifests on astrophysical scales. These simulations typical use a classical field approximation. In this work, we look at extending these simulations to include quantum corrections. We look into both the ways in which large corrections impact the predictions of scalar field dark matter, and the timescales on which these corrections grow large. Corrections tend to lessen density fluctuations and increase the effect of "quantum pressure". During collapse, these corrections grow exponentially, quantum corrections would become important in about $\sim 30$ dynamical times. This implies that the predictions of classical field simulations may differ from those with quantum corrections for systems with short dynamical times.

  1 citation