Publications

Order by: publication date number of citations

• Reconstructing the graviton

  Alfio Bonanno, Tobias Denz, Jan M. Pawlowski, Manuel Reichert

  SciPost Phys. 12, 001 (2022) · published 4 January 2022 | Toggle abstract · pdf

  We reconstruct the Lorentzian graviton propagator in asymptotically safe quantum gravity from Euclidean data. The reconstruction is applied to both the dynamical fluctuation graviton and the background graviton propagator. We prove that the spectral function of the latter necessarily has negative parts similar to, and for the same reasons, as the gluon spectral function. In turn, the spectral function of the dynamical graviton is positive. We argue that the latter enters cross sections and other observables in asymptotically safe quantum gravity. Hence, its positivity may hint at the unitarity of asymptotically safe quantum gravity.

  40 citations

• Diving into a holographic superconductor

  Sean A. Hartnoll, Gary T. Horowitz, Jorrit Kruthoff, Jorge E. Santos

  SciPost Phys. 10, 009 (2021) · published 15 January 2021 | Toggle abstract · pdf

  Charged black holes in anti-de Sitter space become unstable to forming charged scalar hair at low temperatures $T < T_\text{c}$. This phenomenon is a holographic realization of superconductivity. We look inside the horizon of these holographic superconductors and find intricate dynamical behavior. The spacetime ends at a spacelike Kasner singularity, and there is no Cauchy horizon. Before reaching the singularity, there are several intermediate regimes which we study both analytically and numerically. These include strong Josephson oscillations in the condensate and possible 'Kasner inversions' in which after many e-folds of expansion, the Einstein-Rosen bridge contracts towards the singularity. Due to the Josephson oscillations, the number of Kasner inversions depends very sensitively on $T$, and diverges at a discrete set of temperatures $\{T_n\}$ that accumulate at $T_c$. Near these $T_n$, the final Kasner exponent exhibits fractal-like behavior.

  33 citations

• Carroll Expansion of General Relativity

  Dennis Hansen, Niels A. Obers, Gerben Oling, Benjamin T. Søgaard

  SciPost Phys. 13, 055 (2022) · published 8 September 2022 | Toggle abstract · pdf

  We study the small speed of light expansion of general relativity, utilizing the modern perspective on non-Lorentzian geometry. This is an expansion around the ultra-local Carroll limit, in which light cones close up. To this end, we first rewrite the Einstein-Hilbert action in pre-ultra-local variables, which is closely related to the 3+1 decomposition of general relativity. At leading order in the expansion, these pre-ultra-local variables yield Carroll geometry and the resulting action describes the electric Carroll limit of general relativity. We also obtain the next-to-leading order action in terms of Carroll geometry and next-to-leading order geometric fields. The leading order theory yields constraint and evolution equations, and we can solve the evolution analytically. We furthermore construct a Carroll version of Bowen-York initial data, which has associated conserved boundary linear and angular momentum charges. The notion of mass is not present at leading order and only enters at next-to-leading order. This is illustrated by considering a particular truncation of the next-to-leading order action, corresponding to the magnetic Carroll limit, where we find a solution that describes the Carroll limit of a Schwarzschild black hole. Finally, we comment on how a cosmological constant can be incorporated in our analysis.

  29 citations

• EXCESS workshop: Descriptions of rising low-energy spectra

  P. Adari, A. Aguilar-Arevalo, D. Amidei, G. Angloher, E. Armengaud, C. Augier, L. Balogh, S. Banik, D. Baxter, C. Beaufort, G. Beaulieu, V. Belov, Y. Ben Gal, G. Benato, A. Benoît, A. Bento, L. Bergé, A. Bertolini, R. Bhattacharyya, J. Billard, I.M. Bloch, A. Botti, R. Breier, G. Bres, J-.L. Bret, A. Broniatowski, A. Brossard, C. Bucci, R. Bunker, M. Cababie, M. Calvo, P. Camus, G. Cancelo, L. Canonica, F. Cappella, L. Cardani, J.-F. Caron, N. Casali, G.del Castello, A. Cazes, R. Cerulli, B.A. Cervantes Vergara, D. Chaize, M. Chapellier, L. Chaplinsky, F. Charlieux, M. Chaudhuri, A.E. Chavarria, G. Chemin, R. Chen, H. Chen, F. Chierchie, I. Colantoni, J. Colas, J. Cooley, J.-M. Coquillat, E.C. Corcoran, S. Crawford, M. Crisler, A. Cruciani, P. Cushman, A. D'Addabbo, J.C. D'Olivo, A. Dastgheibi-Fard, M. De Jésus, Y. Deng, J.B. Dent, E.L. Depaoli, K. Dering, S. Dharani, S. Di Lorenzo, A. Drlica-Wagner, L. Dumoulin, D. Durnford, B. Dutta, L. Einfalt, A. Erb, A. Erhart, R. Essig, J. Estrada, E. Etzion, O. Exshaw, F. Favela-Perez, F. v. Feilitzsch, G. Fernandez Moroni, N. Ferreiro Iachellini, S. Ferriol, S. Fichtinger, E. Figueroa-Feliciano, J.-B. Filippini, D. Filosofov, J. A. Formaggio, M. Friedl, S. Fuard, D. Fuchs, A. Fuss, R. Gaïor, A. Garai, C. Garrah, J. Gascon , G. Gerbier, M. Ghaith, V.M. Ghete, D. Gift, I. Giomataris, G. Giroux, A. Giuliani, P. Gorel, P. Gorla, C. Goupy, J. Goupy, C. Goy, M. Gros, P. Gros, Y. Guardincerri, C. Guerin, V. Guidi, O. Guillaudin, S. Gupta, E. Guy, P. Harrington, D. Hauff, S. T. Heine, S. A. Hertel, S.E. Holland, Z. Hong, E.W. Hoppe, T.W. Hossbach, J.-C. Ianigro, V. Iyer, A. Jastram, M. Ješkovský, Y. Jin, J. Jochum, J. P. Johnston, A. Juillard, D. Karaivanov, V. Kashyap, I. Katsioulas, S. Kazarcev, M. Kaznacheeva, F. Kelly, B. Kilminster, A. Kinast, L. Klinkenberg, H. Kluck, P. Knights, Y. Korn, H. Kraus, B. von Krosigk, A. Kubik, N.A. Kurinsky, J. Lamblin, A. Langenkämper, S. Langrock, T. Lasserre, H. Lattaud, P. Lautridou, I. Lawson, S.J. Lee, M. Lee, A. Letessier-Selvon, D. Lhuillier, M. Li, Y.-T. Lin, A. Lubashevskiy, R. Mahapatra, S. Maludze, M. Mancuso, I. Manthos, L. Marini, S. Marnieros, R.D. Martin, A. Matalon, J. Matthews, B. Mauri, D. W. Mayer, A. Mazzolari, E. Mazzucato, H. Meyer zu Theenhausen, E. Michielin, J. Minet, N. Mirabolfathi, K. v. Mirbach, D. Misiak, P. Mitra, J-.L. Mocellin, B. Mohanty, V. Mokina, J.-P. Mols, A. Monfardini, F. Mounier, S. Munagavalasa, J.-F. Muraz, X.-F. Navick, T. Neep, H. Neog, H. Neyrial, K. Nikolopoulos, A. Nilima, C. Nones, V. Novati, P. O'Brien, L. Oberauer, E. Olivieri, M. Olmi, A. Onillon, C. Oriol, A. Orly, J.L. Orrell, T. Ortmann, C.T. Overman, C. Pagliarone, V. Palušová, P. Pari, P. K. Patel, L. Pattavina, F. Petricca, A. Piers, H. D. Pinckney, M.-C. Piro, M. Platt, D. Poda, D. Ponomarev, W. Potzel, P. Povinec, F. Pröbst, P. Privitera, F. Pucci, K. Ramanathan, J.-S. Real, T. Redon, F. Reindl, R. Ren, A. Robert, J.Da Rocha, D. Rodrigues, R. Rogly, J. Rothe, N. Rowe, S. Rozov, I. Rozova, T. Saab, N. Saffold, T. Salagnac, J. Sander, V. Sanglard, D. Santos, Y. Sarkis, V. Savu, G. Savvidis, I. Savvidis, S. Schönert, K. Schäffner, N. Schermer, J. Schieck, B. Schmidt, D. Schmiedmayer, C. Schwertner, L. Scola, M. Settimo, Ye. Shevchik, V. Sibille, I. Sidelnik, A. Singal, R. Smida, M. Sofo Haro, T. Soldner, J. Stachurska, M. Stahlberg, L. Stefanazzi, L. Stodolsky, C. Strandhagen, R. Strauss, A. Stutz, R. Thomas, A. Thompson, J. Tiffenberg, C. Tomei, M. Traina, S. Uemura, I. Usherov, L. Vagneron, W. Van De Pontseele, F.A. Vazquez de Sola Fernandez, M. Vidal, M. Vignati, A.L. Virto, M. Vivier, T. Volansky, V. Wagner, F. Wagner, J. Walker, R. Ward, S.L. Watkins, A. Wex, M. Willers, M.J. Wilson, L. Winslow, E. Yakushev, T.-T. Yu, M. Zampaolo, A. Zaytsev, V. Zema, D. Zinatulina, A. Zolotarova

  SciPost Phys. Proc. 9, 001 (2022) · published 9 August 2022 | Toggle abstract · pdf

  Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop’s data repository together with a plotting tool for visualization.

  28 citations

• Search for scalar induced gravitational waves in the international pulsar timing array data release 2 and NANOgrav 12.5 years datasets

  Virgile Dandoy, Valerie Domcke, Fabrizio Rompineve

  SciPost Phys. Core 6, 060 (2023) · published 30 August 2023 | Toggle abstract · pdf

  We perform a Bayesian search in the latest Pulsar Timing Array (PTA) datasets for a stochastic gravitational wave (GW) background sourced by curvature perturbations at scales $10^5$ Mpc$^{-1}\lesssim$ k$\lesssim 10^8$ Mpc$^{-1}$. These re-enter the Hubble horizon at temperatures around and below the QCD crossover phase transition in the early Universe. We include a stochastic background of astrophysical origin in our search and properly account for constraints on the curvature power spectrum from the overproduction of primordial black holes (PBHs). We find that the International PTA Data Release 2 significantly favors the astrophysical model for its reported common-spectrum process, over the curvature-induced background. On the other hand, the two interpretations fit the NANOgrav 12.5 years dataset equally well. We then set new upper limits on the amplitude of the curvature power spectrum at small scales. These are independent from, and competitive with, indirect astrophysical bounds from the abundance of PBH dark matter. Upcoming PTA data releases will provide the strongest probe of the curvature power spectrum around the QCD epoch.

  26 citations

• Strongly Interacting Light Dark Matter

  Sebastian Bruggisser, Francesco Riva, Alfredo Urbano

  SciPost Phys. 3, 017 (2017) · published 2 September 2017 | Toggle abstract · pdf

  In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.

  25 citations

• AMS-02 antiprotons and dark matter: Trimmed hints and robust bounds

  Francesca Calore, Marco Cirelli, Laurent Derome, Yoann Genolini, David Maurin, Pierre Salati, Pasquale D. Serpico

  SciPost Phys. 12, 163 (2022) · published 18 May 2022 | Toggle abstract · pdf

  Based on 4 yr AMS-02 antiproton data, we present bounds on the dark matter (DM) annihilation cross section vs. mass for some representative final state channels. We use recent cosmic-ray propagation models, a realistic treatment of experimental and theoretical errors, and an updated calculation of input antiproton spectra based on a recent release of the PYTHIA code. We find that reported hints of a DM signal are statistically insignificant; an adequate treatment of errors is crucial for credible conclusions. Antiproton bounds on DM annihilation are among the most stringent ones, probing thermal DM up to the TeV scale. The dependence of the bounds upon propagation models and the DM halo profile is also quantified. A preliminary estimate reaches similar conclusions when applied to the 7 years AMS-02 dataset, but also suggests extra caution as for possible future claims of DM excesses.

  22 citations

• Near horizon dynamics of three dimensional black holes

  Daniel Grumiller, Wout Merbis

  SciPost Phys. 8, 010 (2020) · published 23 January 2020 | Toggle abstract · pdf

  We perform the Hamiltonian reduction of three dimensional Einstein gravity with negative cosmological constant under constraints imposed by near horizon boundary conditions. The theory reduces to a Floreanini-Jackiw type scalar field theory on the horizon, where the scalar zero modes capture the global black hole charges. The near horizon Hamiltonian is a total derivative term, which explains the softness of all oscillator modes of the scalar field. We find also a (Korteweg-de Vries) hierarchy of modified boundary conditions that we use to lift the degeneracy of the soft hair excitations on the horizon.

  21 citations

• Breaking away from the near horizon of extreme Kerr

  Alejandra Castro, Victor Godet

  SciPost Phys. 8, 089 (2020) · published 17 June 2020 | Toggle abstract · pdf

  We study gravitational perturbations around the near horizon geometry of the (near) extreme Kerr black hole. By considering a consistent truncation for the metric fluctuations, we obtain a solution to the linearized Einstein equations. The dynamics is governed by two master fields which, in the context of the nAdS$_2$/nCFT$_1$ correspondence, are both irrelevant operators of conformal dimension $\Delta=2$. These fields control the departure from extremality by breaking the conformal symmetry of the near horizon region. One of the master fields is tied to large diffeomorphisms of the near horizon, with its equations of motion compatible with a Schwarzian effective action. The other field is essential for a consistent description of the geometry away from the horizon.

  19 citations

• Quantum null energy condition and its (non)saturation in 2d CFTs

  Christian Ecker, Daniel Grumiller, Wilke van der Schee, Shahin Sheikh-Jabbari, Philipp Stanzer

  SciPost Phys. 6, 036 (2019) · published 25 March 2019 | Toggle abstract · pdf

  We consider the Quantum Null Energy Condition (QNEC) for holographic conformal field theories in two spacetime dimensions (CFT$_2$). We show that QNEC saturates for all states dual to vacuum solutions of AdS$_3$ Einstein gravity, including systems that are far from thermal equilibrium. If the Ryu-Takayanagi surface encounters bulk matter QNEC does not need to be saturated, whereby we give both analytical and numerical examples. In particular, for CFT$_2$ with a global quench dual to AdS$_3$-Vaidya geometries we find a curious half-saturation of QNEC for large entangling regions. We also address order one corrections from quantum backreactions of a scalar field in AdS$_3$ dual to a primary operator of dimension $h$ in a large central charge expansion and explicitly compute both, the backreacted Ryu--Takayanagi surface part and the bulk entanglement contribution to EE and QNEC. At leading order for small entangling regions the contribution from bulk EE exactly cancels the contribution from the back-reacted Ryu-Takayanagi surface, but at higher orders in the size of the region the contributions are almost equal while QNEC is not saturated. For a half-space entangling region we find that QNEC is gapped by $h/4$ in the large $h$ expansion.

  19 citations