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  • Journal article
    Kallosh R, Tseytlin AA, 2026,

    On anomaly-free 4d $$ \mathcal{N} $$ = 4 and 6d (2,0) conformal supergravities and UV finiteness of Poincaré supergravities

    , Journal of High Energy Physics, Vol: 2026

    <jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> We review the structure of superconformal anomalies in 4d <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathcal{N} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> = 4 conformal supergravity (CSG) coupled to a number N <jats:sub>v</jats:sub> of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \mathcal{N} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math> </jats:alternatives> </jats:inline-formula> = 4 vector multiplets and 6d (2,0) CSG coupled to N <jats:sub>T</jats:sub> of (2,0) tensor multiplets. Anomalies cancel if N <jats:sub>v</jats:sub> = 4 and N <jats:sub>T</jats:sub> = 26 respectively. If the CSG part of the action is dropped and N <jats:sub>v</jats:sub> = 6 + n <jats:sub>v</jats:sub> , the first theory is classically equivalent to the 4d <jats:inline-formula>
  • Journal article
    Agazie G, Anumarlapudi A, Archibald AM, Baker PT, Bécsy B, Blecha L, Bonilla A, Brazier A, Brook PR, Burke-Spolaor S, Burnette R, Case R, Casey-Clyde JA, Charisi M, Chatterjee S, Chatziioannou K, Cheeseboro BD, Chen S, Cohen T, Cordes JM, Cornish NJ, Crawford F, Cromartie HT, Crowter K, Cutler CJ, DOrazio DJ, DeCesar ME, DeGan D, Demorest PB, Deng H, Dolch T, Drachler B, Ferrara EC, Fiore W, Fonseca E, Freedman GE, Gardiner E, Garver-Daniels N, Gentile PA, Gersbach KA, Glaser J, Good DC, Gültekin K, Hazboun JS, Hourihane S, Islo K, Jennings RJ, Johnson A, Jones ML, Kaiser AR, Kaplan DL, Kelley LZ, Kerr M, Key JS, Laal N, Lam MT, Lamb WG, W Lazio TJ, Lewandowska N, Littenberg TB, Liu T, Luo J, Lynch RS, Ma CP, Madison DR, Matt C, McEwen A, McKee JW, McLaughlin MA, McMann N, Meyers BW, Meyers PM, Mingarelli CMF, Mitridate A, Natarajan P, Ng C, Nice DJ, Ocker SK, Olum KD, Pennucci TT, Perera BBP, Petrov P, Pol NS, Radovan HA, Ransom SM, Ray PS, Romano JD, Runnoe JC, Sardesai SC, Schmiedekamp A, Schmiedekamp C, Schmitz K, Schult L, Shapiro-Albert BJ, Siemens X, Simon J, Siwek MS, Stairs IH, Stinebring DR, Stovall Ket al., 2026,

    Erratum: “The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background” (2023, ApJL, 952, L37)

    , Astrophysical Journal Letters, Vol: 1006, ISSN: 2041-8205

    In the published article, we presented inferences about the population of supermassive black hole (SMBH) binaries emitting at nanohertz gravitational-wave (GW) frequencies based on the 15 yr dataset from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). Here, we report two bugs in the astrophysical analysis software used for the published article. While parameter posteriors of our inference can be seen to have slight differences on close inspection, none of the conclusions from the original publication have changed, including the finding that the measured GW background is dominated by the most massive, high-mass-ratio SMBH binaries. Our corrected results show slightly less evidence for environmental interactions with SMBH binaries and indicate that the population of SMBH binaries contributing to the GW background occurs at slightly higher mass ratios and redshifts than indicated in the published article. Correcting these errors does not change the central conclusion that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency GW spectrum. These errors did not affect any other analyses of the NANOGrav 15 yr dataset, including the evidence for a GW background presented in another of our published articles.
  • Journal article
    Gaar F, Gauntlett JP, Park J, Sparks Jet al., 2026,

    Superconformal index and localizing higher derivative supergravity

    , Physical Review D, Vol: 114, ISSN: 2470-0010

    <jats:p> We show how equivariant localization can be used to compute the on shell action for supersymmetric <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>D</a:mi> <a:mo>=</a:mo> <a:mn>5</a:mn> </a:math> anti–de Sitter rotating, charged black holes in theories of supergravity with higher derivatives. An exact match with a dual field theory computation of the superconformal index in a Cardy-like limit is achieved. </jats:p>
  • Journal article
    Matt C, Gültekin K, Agazie G, Agarwal N, Anumarlapudi A, Archibald AM, Arzoumanian Z, Baier JG, Baker PT, Bécsy B, Blecha L, Brazier A, Brook PR, Burke-Spolaor S, Burnette R, Case R, Casey-Clyde JA, Charisi M, Chatterjee S, Cohen T, Cordes JM, Cornish NJ, Crawford F, Cromartie HT, Crowter K, DeCesar ME, Demorest PB, Deng H, Dey L, Dolch T, Doskoch GM, Ferrara EC, Fiore W, Fonseca E, Freedman GE, Gardiner EC, Garver-Daniels N, Gentile PA, Gersbach KA, Glaser J, Good DC, Harris CJ, Hazboun JS, Jennings RJ, Johnson AD, Jones ML, Kaplan DL, Sreekumar AK, Kelley LZ, Kerr M, Key JS, Laal N, Lam MT, Lamb WG, Larsen B, Lazio TJW, Lewandowska N, Liu T, Lorimer DR, Luo J, Lynch RS, Ma CP, Madison DR, Martsen A, McEwen A, McKee JW, McLaughlin MA, McMann N, Meyers BW, Meyers PM, Mingarelli CMF, Mitridate A, Ng C, Nice DJ, Nichols S, Ocker SK, Olum KD, Pennucci TT, Perera BBP, Petrov P, Pol NS, Radovan HA, Ransom SM, Ray PS, Romano JD, Runnoe JC, Saffer A, Sardesai SC, Schmiedekamp A, Schmiedekamp C, Schmitz K, Shapiro-Albert BJ, Siemens X, Simon J, Fiscella SVS, Stairs IH, Stinebring DR, Stovall K, Susobhanan A, Swiggum JKet al., 2026,

    Gravitational-wave Measurement of the MBH–Mbulge Intrinsic Scatter at High Redshift

    , Astrophysical Journal, Vol: 1006, ISSN: 0004-637X

    The observed gravitational-wave background (GWB) spectrum is higher in amplitude than model predictions by a factor of 2–3. Using a semi-analytic model, we evaluate the effect of a high-scatter supermassive black hole (SMBH) scaling relation (M<inf>BH</inf>–M<inf>bulge</inf>) on models of the nanohertz GWB. By implementing an intrinsic scatter of the M<inf>BH</inf>–M<inf>bulge</inf> relation, which is larger at higher redshift, but matches local observations, we find that the amplitude of GWB models increases to be consistent with the low-frequency end of the GWB spectrum. This amplitude increase is not uniform across frequencies, a strongly evolving scatter preferentially increases the number density of the most massive SMBHs which, in the GWB spectrum, minimizes the strength of the low-frequency turnover. Our models with positively evolving intrinsic scatter can reproduce the electromagnetically observed overmassive SMBHs at 4 < z < 6 without changing the M<inf>BH</inf>–M<inf>bulge</inf> normalization though we find that including moderate normalization evolution marginally improves fits to the GWB data. We conclude that the M<inf>BH</inf>–M<inf>bulge</inf> relation which best describes the available GWB and electromagnetic data sets has intrinsic scatter that evolves as (Formula presented) ε(z)=ε0+(0.56±0.4)log10(1+z) and normalization that evolves as α(z) = α<inf>0</inf>(1 + z)<sup>0.84±0.35</sup>. The results of this work imply that the M<inf>BH</inf>–M<inf>bulge</inf> relation we see today is not universal throughout cosmic time and that a diversity of seeding models and growth mechanisms may be at play in the early stages of SMBH–galaxy evolution.
  • Journal article
    Bennett S, Hanany A, Kumaran G, Mansi Let al., 2026,

    Symmetry mitosis and Hasse diagram diamonds: a note on brane configurations with ON0 planes

    , Journal of High Energy Physics, Vol: 2026

    This letter considers 3d N = 4 (unitary-)orthosymplectic quiver gauge theories originating from Type IIA and Type IIB brane systems with ON<sup>0</sup> planes. Such theories lie outside the scope of present combinatorial techniques for Coulomb branch symmetry and symplectic stratification. It turns out that the correct prescription involves ‘symmetry mitosis’: a common subset of nodes in two linear balanced chains source two factors of a Coulomb branch global symmetry instead of one; the correct Coulomb branch Hasse diagram is obtained by a ‘doubling’ procedure on that computed by naive quiver subtraction. Input from 6d SQFTs and little string theories allows for the construction of various ‘mitotic’ magnetic quivers. The full Higgs branch Hasse diagram of minimal (E<inf>6</inf>, E<inf>6</inf>) conformal matter is given. Additionally, a new Type I<sup>′</sup> brane system using eight full D8 branes, negatively charged D6 branes, and ON<sup>0</sup> planes is found corresponding to a product of Spin(32) instantons on ℂ<sup>2</sup>. The corresponding 6d theory uses Sp(−1) gauge nodes which have the interpretation of bi-spinor matter of O(a) and O(12 − a) for a = 0, 1, · · ·, 12.
  • Journal article
    Bennett S, Hanany A, Kumaran G, 2026,

    Quotient quiver subtraction — Classical groups

    , Journal of High Energy Physics, Vol: 2026

    Quotient quiver subtraction is a simple combinatorial prescription for gauging Coulomb branch isometry subgroups of 3d N = 4 quiver gauge theories. This paper uses Type IIB brane constructions with O5 planes to extend the prescription to gauge Sp(n), SO(n), and Sp(n) coupled to a half-hypermultiplet Coulomb branch isometry subgroups of quivers with unitary gauge groups. The gauging procedure is no longer solely a subtraction — additional steps change the graph type. The method is applied to provide alternative constructions of the Higgs branch of certain SCFTs in higher dimensions.
  • Journal article
    Borissova J, Magueijo J, 2026,

    Modified Friedmann equations and non-singular cosmologies in d = 4 non-polynomial quasi-topological gravities

    , Journal of Cosmology and Astroparticle Physics, Vol: 2026

    Quasi-topological theories of gravity are known to resolve black-hole singularities. We investigate whether the same mechanism can remove cosmological singularities. Focusing on non-polynomial curvature quasi-topological gravities in d = 4 dimensions, we find three generic scenarios with the correct infrared limit but without a Big-Bang singularity, for universes filled with pure radiation or other standard matter. The first scenario yields a universe emerging from a de Sitter phase, a case for which the curvature invariants remain finite but the matter density diverges, albeit only at infinite affine distance. The second one corresponds to a bouncing universe, and requires a multi-valued Lagrangian. The third possibility is an asymptotically Minkowski origin, reminiscent of an eternally loitering universe. The matter energy density for this solution is non-singular even at infinite affine distance and does not enter a super-Planckian regime, but is instead approximately constant for the past eternity.
  • Journal article
    Bennett S, Hanany A, Kalveks R, 2026,

    Quiver maps, nilpotent orbits and Special Pieces of nilcones

    , Journal of High Energy Physics, Vol: 2026

    This paper explores 3d N = 4 quiver gauge theories whose moduli spaces represent nilpotent orbits, Słodowy slices or, more generally, Słodowy intersections, which span the Special Pieces of nilcones of Classical or Exceptional algebras. We introduce a map between magnetic and electric quivers containing symmetric group actions, such as wreathings (or loops), bouquets, and/or non-simply laced foldings, which can be related to symmetric subgroups of Lusztig’s canonical quotient groups for Special Pieces. This map on quivers induces a new map on nilpotent orbits that partially resolves the obstruction to quiver dualities presented by the non-involutive nature of the Lusztig Spaltenstein and Barbasch Vogan maps. We use Coulomb and Higgs branch quiver methods complemented by localisation formulae for verification. Some new quivers for intersections within Exceptional nilcones are presented.
  • Journal article
    Agazie G, Anumarlapudi A, Archibald AM, Arzoumanian Z, Baier JG, Baker PT, Bécsy B, Bhoonah A, Blecha L, Brazier A, Brook PR, Burke-Spolaor S, Burnette R, Case R, Casey-Clyde JA, Charisi M, Chatterjee S, Cohen T, Cordes JM, Cornish NJ, Crawford F, Cromartie HT, Crowter K, DeCesar ME, Demorest PB, Deng H, Dey L, Dolch T, Ferrara EC, Fiore W, Fonseca E, Freedman GE, Gardiner EC, Garver-Daniels N, Gentile PA, Gersbach KA, Glaser J, Gómez-Cortes BD, Good DC, Gültekin K, Harris CJ, Hazboun JS, Jennings RJ, Johnson AD, Jones ML, Kaplan DL, Kelley LZ, Kerr M, Key JS, Laal N, Lam MT, Lamb WG, Larsen B, Lazio TJW, Lewandowska N, Leys M, Liu T, Lorimer DR, Luo J, Lynch RS, Ma CP, Madison DR, Matt C, McEwen A, McKee JW, McLaughlin MA, McMann N, Meyers BW, Meyers PM, Mingarelli CMF, Mitridate A, Ng C, Nice DJ, Ocker SK, Olum KD, Pennucci TT, Perera BBP, Petrov P, Pol NS, Radovan HA, Ransom SM, Ray PS, Romano JD, Runnoe JC, Saffer A, Sardesai SC, Schmiedekamp A, Schmiedekamp C, Schmitz K, Shapiro-Albert BJ, Siemens X, Simon J, Fiscella SVS, Stairs IH, Stinebring DR, Stovall K, Susobhanan A, Swiggum JK, Taylor J, Taylor SRet al., 2026,

    The NANOGrav 15 yr Data Set: Piecewise Power-law Reconstruction of the Gravitational-wave Background

    , Astrophysical Journal Letters, Vol: 1004, ISSN: 2041-8205

    The NANOGrav 15 yr (NG15) data set provides evidence for a gravitational-wave background (GWB) signal at nHz frequencies, which is expected to originate either from a cosmic population of inspiraling supermassive black hole binaries or new particle physics in the early Universe. A firm identification of the source of the NG15 signal requires an accurate reconstruction of its frequency spectrum. In this Letter, we provide such a spectral characterization of the NG15 signal based on a piecewise power-law (PPL) ansatz that strikes a balance between existing alternatives in the literature. Our PPL reconstruction is more flexible than the standard constant power-law model, which describes the GWB spectrum in terms of only two parameters: an amplitude A and a spectral index γ. Concurrently, it better approximates physically realistic GWB spectra—especially those of cosmological origin—than the free spectral model, since the latter allows for arbitrary variations in the GWB amplitude from one frequency bin to the next. Our PPL reconstruction of the NG15 signal relies on individual PPL models with a fixed number of internal nodes (i.e., constant power law, broken power law, doubly broken power law, etc.), which are ultimately combined in a Bayesian model average. The data products resulting from our analysis provide the basis for fast refits of spectral GWB models.
  • Journal article
    Vaglio M, Falxa M, Mentasti G, Renzini AI, Kuntz A, Barausse E, Contaldi CR, Sesana Aet al., 2026,

    Searching for gravitational waves with Gaia and its cross-correlation with PTA: absolute vs differential astrometry

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    Astrometric missions like Gaia provide exceptionally precise measurements of stellar positions, parallaxes, and proper motions. Gravitational waves traveling between the observer and distant stars can induce small, correlated shifts in their apparent positions, a phenomenon known as astrometric deflection. The precision and scale of astrometric datasets make them well suited for searching for a stochastic gravitational-wave background, whose signature appears in the two-point correlation function of the deflection field across the sky. In space-based astrometry, the ultimate sensitivity of such measurements is reduced by systematic uncertainties in the satellite’s absolute attitude reconstruction, which constrain the accuracy of absolute astrometry. These orientation errors can be mitigated by focusing on relative angular separation between pairs of stars, which effectively cancel out common-mode orientation noise. In this work, we compute the astrometric response and the overlap reduction functions for this differential approach, correcting previous expressions presented in the literature. We use a Fisher matrix analysis to compare the sensitivity of differential astrometry to that of conventional absolute astrometry. Our analysis shows that while the differential method is theoretically sound, its sensitivity is limited for closely spaced star pairs. Pairs with large angular separations provide competitive sensitivity, but, when considered in connection with Gaia, it is unclear whether the differential strategy would be effective, since instrumental systematics are not expected to remain correlated on such scales. Finally, we demonstrate that combining astrometric data with observations from pulsar-timing arrays leads to slight improvements in sensitivity at frequencies ≳10−7  Hz.
  • Journal article
    Vicente García-Consuegra L, Rajantie A, 2026,

    Scalar effective potentials in de Sitter spacetime

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    <jats:p>We investigate two different definitions of a scalar field effective potential in quantum field theory in de Sitter spacetime: the standard textbook definition, and the constraint effective potential proposed by O’Raifeartaigh in 1986. While these definitions are equivalent in Minkowski spacetime, they differ significantly in de Sitter spacetime. We demonstrate this by computing them both explicitly at one-loop order in perturbation theory. It is well known that the perturbative expansion of the standard effective potential fails to converge for light fields. In contrast, the constraint effective potential does not suffer from this infrared problem, and it can therefore be computed using perturbation theory. We discuss the physical interpretation of the two effective potentials. In particular, we provide evidence supporting an earlier conjecture that the constraint effective potential is the correct one to use in the stochastic Starobinsky-Yokoyama theory.</jats:p>
  • Journal article
    Isichei R, Magueijo J, 2026,

    Lorentz Violation in Emergent Gravity and Its Cosmological Consequences.

    , Phys Rev Lett, Vol: 136

    We show that general relativity and other geometrical theories can be viewed as a degenerate Otto cycle with only heat-exchange legs in emergent gravity. Including work-producing legs yields controlled violations of local Lorentz invariance and energy-momentum conservation, which produce late-time cosmological acceleration. Implications for the cosmological constant problem, structure formation, and local observations are discussed.
  • Journal article
    Tseytlin AA, Wang Z, 2026,

    Wilson loop in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>AdS</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> <mml:mo>×</mml:mo> <mml:msup> <mml:mi>S</mml:mi> <mml:mn>3</mml:mn> </mml:msup> <mml:mo>×</mml:mo> <mml:msup> <mml:mi>T</mml:mi> <mml:mn>4</mml:mn> </mml:msup> </mml:mrow> </mml:math> from quantum M2 brane

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    <jats:p> Type-IIB string theory on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msub> <a:mtext>AdS</a:mtext> <a:mn>3</a:mn> </a:msub> <a:mo>×</a:mo> <a:msup> <a:mi>S</a:mi> <a:mn>3</a:mn> </a:msup> <a:mo>×</a:mo> <a:msup> <a:mi>T</a:mi> <a:mn>4</a:mn> </a:msup> </a:math> with Ramond–Ramond flux as the near-horizon limit of the D1-D5 solution is expected to be dual to a (4, 4) supersymmetric 2D conformal field theory (CFT) parametrized by the integers <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>Q</c:mi> <c:mn>1</c:mn> </c:msub> </c:math> , <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msub> <e:mi>Q</e:mi> <e:mn>5</e:mn> </e:msub> </e:math> , and other moduli. It is related by T-duality to type-IIA string theory in the near-horizon limit of the D2-D4 solution, which admits an uplift to the 11D <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inl
  • Journal article
    Chiang HW, de Rham C, Garcia-Saenz S, Zhou Xet al., 2026,

    Cosmological tensions in Proca-Nuevo theory

    , Journal of Cosmology and Astroparticle Physics, Vol: 2026

    We study the cosmological predictions of (extended) Proca-Nuevo theory. This vector-tensor theory enjoys stable homogeneous and isotropic solutions characterized by an effective dark energy fluid, with behavior that ranges from freezing quintessential to thawing phantom-like, serving as a motivated framework to scrutinize the cosmological tensions that affect the standard ΛCDM model. While the model we consider is sufficiently generic to encompass a large class of field theories, it distinguishes itself from scalar dark energy models (quintessential ones, kinetic ones and non-minimally coupled ones) by the presence of what would be classed as a vector degree of freedom which can be for instance inherited from more generic theories of gravity. We improve on previous work in several directions: we consider a general one-parameter class of background models; identify a so-called 'special' model and analyze observational constraints taking also into account perturbations and making use of wide up-to-date catalogs of datasets including recently released ones. We find that the one-parameter Proca-Nuevo model is preferred over ΛCDM at 1.5σ when fitting CMB and BAO data, and at 2.4σ when further adding low-redshift data. The Hubble tension is alleviated, dropping from 5.σ to 2.3σ (resp. 1.5σ) between CMB with (and resp. without) BAO data and local measurements. On the other hand, we find that the vector field generically introduces a significant enhancement of the effective Newton constant for natural values of parameters, so that matching the observed matter power spectrum requires a mild amount of tuning to suppress the impact of perturbations. Since, at the background level, Proca-Nuevo is degenerate with other classes of theories, our results are also relevant to a wider range of set-ups including and beyond vector-tensor models.
  • Journal article
    de Rham C, Jaitly S, Kaplanek G, 2026,

    Mixed signals in the IR: positivity bounds with indefinite species

    , Journal of High Energy Physics, Vol: 2026

    In theories with multiple particle species standard fixed-t positivity bounds do not directly apply to 2-to-2 definite species scattering amplitudes when the initial and final state are not the same (inelastic processes). These inelastic amplitudes are nevertheless constrained by positivity bounds indirectly, by considering scattering states which are arbitrary superpositions of definite species two-particle states. While these ‘superposition bounds’ have been studied and utilised extensively in the past, earlier analyses typically consider cases insensitive to relative particle masses and IR branch cuts. Here we derive new families of bounds that take account and depend explicitly on mass differences between species making no assumption of weak-coupling. We emphasise unusual non-analyticities induced by the IR mass difference within the superposition amplitude and use fixed (backwards) angle dispersion relations to prove our bounds. We then discuss extensions of our results to ‘improved bounds’, with implications worth exploring for pions and other EFTs of the Standard Model and Beyond, particularly where IR branch cuts are non-negligible.
  • Journal article
    Hull C, 2026,

    Self-dual gauge fields from superstring field theory

    , Journal of High Energy Physics, Vol: 2026

    The action for self-dual gauge fields that emerges from the recently constructed superstring field theory is found. The new superstring field theory reduces to that of Sen in a certain limit, and in this limit the new action for self-dual gauge fields reduces to Sen’s action for such fields. The theory describes two decoupled self-dual gauge fields that couple to two metrics, with each gauge field coupling to only one of the metrics. The action also features a background metric, and the non-linear coupling to these three metrics is non-standard. There are two spin-two gauge invariances, and diffeomorphisms arise from the diagonal subgroup.
  • Journal article
    Chester SM, Mouland R, van Muiden J, Virally Cet al., 2026,

    Extremal couplings and gluon scattering in M-theory

    , Journal of High Energy Physics, Vol: 2026

    We consider M-theory on the backgrounds AdS4×S7/ℤNf and AdS<inf>7</inf> × S<sup>4</sup>/ℤ<inf>2</inf>, which have fixed point loci AdS<inf>d+1</inf> × S<sup>3</sup> for d = 3, 6. These theories are holographically dual to certain CFTs in d = 3, 6 with eight supercharges. We compute the bulk cubic couplings between graviton KK modes and gluon KK modes living on the fixed points of these theories, which are generically extremal. We use these couplings to compute the graviton exchange term that appears in the strong coupling expansion of holographic correlators of gluon KK modes 〈22pp〉 in these theories, and check that it matches the expected flat space limit. We express the answer in terms of a new reduced correlator solution to the superconformal Ward identities, which we derive for all CFTs with eight supercharges in 3 ≤ d ≤ 6.
  • Journal article
    Arav I, Gauntlett JP, Roberts MM, Rosen Cet al., 2026,

    Spindle solutions, hyperscalars and smooth uplifts

    , Journal of High Energy Physics (JHEP), Vol: 2026, ISSN: 1126-6708

    We construct AdS3 × Y7 solutions of type IIB supergravity, where Y7 is a smooth S5 bundle over a spindle Σ(nN, nS), which are dual to 𝒩 = (0, 2) SCFTs in d = 2. The solutions are constructed using the D = 5 STU U(1)3 gauged supergravity theory coupled to a hyperscalar charged under U(1)B. We investigate spindle solutions with two new features: first, we allow (nN, nS) to be non-coprime integers, including orbifolds of the round S2, which can lead to non-unique, inequivalent uplifts, distinguished by the hyperscalar spectra, for given magnetic flux through the spindle. Second, we also allow the hyperscalar to vanish at the poles leading to solutions carrying non-vanishing U(1)B flux. The new hyperscalar AdS3 solutions can naturally arise as the endpoint of RG flows, triggered by relevant hyperscalar deformations of the AdS3 solutions of the STU model.
  • Journal article
    Gersbach KA, Taylor SR, Bécsy B, Lemke A-M, Mitridate A, Pol Net al., 2026,

    Mapping the gravitational-wave background across the spectrum with a next-generation anisotropic per-frequency optimal statistic

    , Physical Review D, Vol: 113, ISSN: 2470-0010
  • Journal article
    Chester SM, Piazza A, Reehorst M, Su Net al., 2026,

    Bootstrapping the simplest deconfined quantum critical point

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    <jats:p> We study the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>N</a:mi> <a:mo>=</a:mo> <a:mn>3</a:mn> </a:math> case of the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>C</c:mi> <c:msup> <c:mi>P</c:mi> <c:mrow> <c:mi>N</c:mi> <c:mo>−</c:mo> <c:mn>1</c:mn> </c:mrow> </c:msup> </c:math> model, which is a field theory of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>N</e:mi> </e:math> complex scalars in <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mn>3</g:mn> <g:mi>d</g:mi> </g:math> coupled to an Abelian gauge field with <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mi>S</i:mi> <i:mi>U</i:mi> <i:mo stretchy="false">(</i:mo> <i:mi>N</i:mi> <i:mo stretchy="false">)</i:mo> <i:mo>×</i:mo>
  • Journal article
    Chen Y, Daniel M, DOrazio DJ, Fan X, Mitridate A, Sagunski L, Xue X, Young O, Wright D, Witt CA, Wahl HM, Vigeland SJ, van Haasteren R, Vallisneri M, Ünal C, Turner JE, Taylor SR, Taylor J, Swiggum JK, Susobhanan A, Stovall K, Stinebring DR, Stairs IH, Sosa Fiscella SV, Siwek MS, Simon J, Siemens X, Shapiro-Albert BJ, Schmitz K, Schmiedekamp C, Schmiedekamp A, Sardesai SC, Saffer A, Runnoe JC, Romano JD, Ray PS, Ransom SM, Radovan HA, Pol NS, Petrov P, Perera BBP, Pennucci TT, Olum KD, Ocker SK, Nice DJ, Ng C, Mingarelli CMF, Meyers PM, Meyers BW, McMann N, McLaughlin MA, McKee JW, McEwen A, Madison DR, Ma CP, Lynch RS, Luo J, Lorimer DR, Liu T, Lewandowska N, Lazio TJW, Larsen B, Lamb WG, Lam MT, Laal N, Key JS, Kerr M, Kelley LZ, Kaplan DL, Jones ML, Johnson AD, Jennings RJ, Hazboun JS, Gültekin K, Good DC, Glaser J, Gersbach KA, Gentile PA, Garver-Daniels N, Gardiner EC, Freedman GE, Fonseca E, Fiore W, Ferrara EC, Dolch T, Dey L, Deng H, Demorest PB, DeCesar ME, Crowter K, Cromartie HT, Crawford F, Cornish NJ, Cordes JM, Cohen T, Chatterjee S, Charisi M, Casey-Clyde JA, Burnette R, Burke-Spolaor Set al., 2026,

    Inference on inner galaxy structure via gravitational waves from supermassive binaries

    , Nature Astronomy, Vol: 10, Pages: 554-563

    The detection of a stochastic gravitational wave background by pulsar-timing arrays indicates the presence of a population of supermassive black hole binaries. Although the observed spectrum generally matches predictions for orbital evolution driven by gravitational-wave emission in circular orbits, there is a preference for a spectral turnover at the lowest observed frequencies, which may point to substantial hardening during a transition from early environmental influences to later stages dominated by emission. In the vicinity of these binaries, the ejection of stars or dark matter particles through gravitational three-body slingshots efficiently extracts orbital energy, leading to a low-frequency turnover in the spectrum. Here we model how the gravitational-wave spectrum depends on the initial inner galactic profile before scouring by binary ejections while accounting for a range of initial binary eccentricities. By analysing the NANOGrav 15-year data, we find that a parsec-scale galactic-centre density of around 10<sup>6</sup> M<inf>⊙</inf> pc<sup>−</sup><sup>3</sup> is favoured across most of the parameter space, thus shedding light on the environmental effects that shape black hole evolution and the combined matter density near galaxy centres.
  • Journal article
    Abril-Cabezas I, Challinor A, Clarke P, Coulton W, Embil Villagra C, Fergusson J, Legrand L, McCarthy F, Namikawa T, Sailer N, Shellard P, Sherwin B, Suman P, Zubeldia I, Bolliet B, Challinor A, Clarke P, Coulton W, Fergusson J, Hertig E, Kusiak A, Legrand L, McCarthy F, Namikawa T, Sherwin B, Adachi S, Adachi S, Ashton P, Chinone Y, Jost B, Katayama N, Kusaka A, Liu J, Matsumura T, Namikawa T, Sakurai Y, Tajima O, Takakura S, Ade P, Barry P, Braithwaite C, Brien TLR, Calabrese E, Desai S, Doyle S, Giardiello S, Hargrave P, Harrison I, Jense HT, Lyons M, Negrello M, Papageorgiou A, Rowe S, Sudiwala R, Tucker C, Veenendaal I, Viña M, Adler AE, Ali A, Ashton P, Baleato Lizancos A, Beckman S, Corbett L, Crowley KT, Cukierman A, Ferraro S, Goeckner-Wald N, Hadzhiyska B, Hill CA, Jeong O, Krolewski A, Lee A, Linder E, Prasad B, Randall MJ, Raum C, Seljak U, Song X, Stein G, Westbrook B, Yu B, Adler AE, Keskitalo R, Kisner T, Adler AE, Agrawal P, Arnold K, Bixler B, Boettger D, Chu M, Crowley KT, Flauger R, Fuller G, Green D, Idicherian Lonappan A, Johnson A, Keating Bet al., 2026,

    The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes

    , Journal of Cosmology and Astroparticle Physics, Vol: 2026, ISSN: 1475-7516

    We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a B-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a 1/f noise model with knee multipole ℓ<inf>knee</inf> = 50 and a moderately complex model for Galactic foregrounds, we forecast a 1σ (or 68% confidence level) constraint on the tensor-to-scalar ratio r of σ<inf>r</inf> = 1.2 × 10<sup>-3</sup>, assuming no primordial B-modes are present. This forecast assumes that 70% of the B-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to σ<inf>r</inf> = 7 × 10<sup>-4</sup>. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey.
  • Journal article
    Beccaria M, Kurlyand SA, Tseytlin AA, 2026,

    Strong coupling expansion of 12 BPS Wilson loop in SYM theory and 2-loop Green-Schwarz string in AdS5 × S5

    , Nuclear Physics B, Vol: 1025, ISSN: 0550-3213

    The exact localization result for the expectation value of the 12 BPS circular Wilson loop in N=4 SYM theory is given in the planar limit by the famous Bessel function expression: 〈W〉=2NλI<inf>1</inf>(λ). Expanded in large λ and expressed in terms of the AdS<inf>5</inf> × S <sup>5</sup> string tension T=λ2π this gives 〈W〉=T2πg<inf>s</inf>e<sup>2πT</sup>(1−316πT<sup>−1</sup>+…).The exponential is matched by the value of the action of the string with the AdS<inf>2</inf> world volume while the prefactor comes from the 1-loop GS string correction. Here we address the question of how the subleading T<sup>−1</sup> term could be reproduced by the 2-loop correction in the corresponding partition function of the AdS<inf>5</inf> × S <sup>5</sup> GS string expanded near the AdS<inf>2</inf> minimal surface. We find that the string correction contains a non-zero UV logarithmic divergence implying that comparison with the SYM result requires a particular subtraction prescription. We discuss implications of this conclusion for checking the AdS/CFT duality at strong coupling.
  • Journal article
    Elder B, Gawrych K, Rajantie A, 2026,

    Constrained instantons in scalar field theories

    , Journal of High Energy Physics (JHEP), Vol: 2026, ISSN: 1126-6708

    Instantons, localised saddle points of the action, play an important role in describing non-perturbative aspects of quantum field theories, for example vacuum decay or violation of conservation laws associated with anomalous symmetries. However, there are theories in which no saddle point exists. In this paper, we revisit the idea of constrained instantons, proposed initially by Affleck in 1981, and develop it into a complete method for computing the vacuum decay rate in such cases. We apply this approach to the massive scalar field theory with a negative quartic self-interaction using two different constraints. We solve the field equations numerically and find a two-branch structure, with two distinct solutions for each value of the constraint. By counting the negative modes, we identify one branch of solutions as the constrained instantons and the other as the minima of the action subject to the constraint. We discuss their significance for the computation of the vacuum decay rate.
  • Journal article
    Tseytlin AA, Wang Z, 2026,

    On world-volume supersymmetry of supermembrane action in static gauge

    , Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences, Vol: 482, ISSN: 1364-5021

    We review and elaborate on the issue of three-dimensional (3D) world-volume supersymmetry that appears as a residual part of global target space supersymmetry in the Bergshoeff–Sezgin–Townsend (BST) supermembrane action. While there is no direct ‘spinning membrane’ analogue of the world-volume supersymmetric spinning string action that could be obtained by coupling (Formula presented) copies of 3D scalar multiplet to 3D supergravity, we discuss how one may construct an (Formula presented) 3D supersymmetric analogue of the derivative expansion of the bosonic membrane action in static gauge. We compare the resulting (Formula presented) supersymmetric action for eight 3D scalar multiplets to the (Formula presented) 3D supersymmetric action describing the (Formula presented) supermembrane in the static gauge. The two actions are not equivalent which is related to the fact that the full (Formula presented) supersymmetry of the static-gauge (Formula presented) supermembrane action can be realized only if the fermions are described by an (Formula presented) spinor rather than vector. The two actions are still directly related in special dimensions (Formula presented) and 5. We also compute the one-loop world-volume scattering amplitudes for the two theories finding that they indeed agree for (Formula presented) but disagree for (Formula presented).
  • Journal article
    Gan X, Kim H, Mitridate A, 2026,

    Probing quadratically coupled ultralight dark matter with pulsar timing arrays

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    <jats:p>Ultralight dark matter may couple quadratically to Standard Model particles. Such quadratic interactions give rise to both coherent and stochastic signals in pulsar timing array (PTA) observations. In this work, we characterize these signals, including the effects of dark matter propagation in a finite-density medium, and assess the sensitivity of current and upcoming PTA observations to their detection. For coherent signals, we find that the sensitivity of current PTA observations competes with and sometimes exceeds that of other probes, such as equivalence principle tests and atomic clocks. For stochastic signals, we find that PTA sensitivities underperform equivalence principle constraints for both existing and upcoming PTA datasets.</jats:p>
  • Journal article
    Genolini PB, Gauntlett JP, Jiao Y, Park J, Sparks Jet al., 2026,

    Equivariant localization for D = 5 gauged supergravity

    , Journal of High Energy Physics (JHEP), Vol: 2026, ISSN: 1126-6708

    We consider supersymmetric solutions of D = 5 Euclidean gauged supergravity coupled to an arbitrary number of vector multiplets. We consider solutions that admit boththe R-symmetry Killing vector, K, constructed as a bilinear in the Killing spinor, as well as an additional Killing vector ℓ. Using ℓ to perform a dimensional reduction to D = 4,N =2 gauged supergravity, we show how the D = 5 on-shell action can be computed using equivariant localization. We illustrate the formalism with some examples, computing thesupersymmetric Casimir energy and the supersymmetric index of the dual SCFT without using the explicit supergravity solutions.
  • Journal article
    Arias-Tamargo G, Hull C, Velásquez Cotini Hutt ML, 2026,

    Nonrenormalization of coupling constants from categorical symmetries in two dimensions

    , Physical Review D, Vol: 113, ISSN: 2470-0010

    <jats:p> We study the role of categorical symmetries in constraining the renormalization of couplings in two-dimensional nonlinear sigma models with a Wess-Zumino term. A large class of these theories admits self-duality symmetries associated with discrete gauging and T-duality. They are generically nonconformal, but we argue that a particular coupling is protected from quantum corrections by the categorical symmetry. We give strong evidence for this claim by showing that the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>β</a:mi> </a:math> -function for this coupling vanishes to 2-loop order if and only if this symmetry is present. Furthermore, in cases where the target space is a group manifold, the nonrenormalization result can be proven to hold nonperturbatively. </jats:p>
  • Journal article
    Beccaria M, Kurlyand SA, Tseytlin AA, 2026,

    2-loop free energy of M2 brane in AdS7 × S4 and surface defect anomaly in (2,0) theory

    , Journal of High Energy Physics, Vol: 2026

    12-BPS surface operator viewed as a conformal defect in rank N 6d (2,0) theory is expected to have a holographic description in terms of a probe M2 brane wrapped on AdS<inf>3</inf> in the AdS<inf>7</inf> × S<sup>4</sup> M-theory background. The M2 brane has the effective tension T<inf>2</inf> = 2πN so that the large tension expansion corresponds to the 1/N expansion. The value of the defect conformal anomaly coefficient in SU(N) (2,0) theory was previously argued to be b= 12N – 9 – 3N<sup>−1</sup>. Semiclassically quantizing M2 brane it was found in arXiv:2004.04562 that the first two terms in b are indeed reproduced by the classical and 1-loop corrections to the M2 free energy. Here we address the question if the 2-loop term in the M2 brane free energy reproduces the N<sup>−1</sup> term in b. Remarkably, despite the general non-renormalizability of the standard BST M2 brane action we find that the 2-loop correction to the free energy of the AdS<inf>3</inf> M2 brane in AdS<inf>7</inf> × S<sup>4</sup> is UV finite (modulo power divergences that can be removed by an analytic regularization). Moreover, the 2-loop correction vanishes in the dimensional and ζ-function regularizations. This result appears to be in disagreement with the non-vanishing of the coefficient of the N<sup>−1</sup> term in the expected expression for the anomaly coefficient b. We discuss possible resolutions of this puzzle, including the one that the M2 brane probe computation may be capturing the surface defect anomaly in the U(N) rather than the SU(N) boundary 6d CFT.
  • Journal article
    Borissova J, Magueijo J, 2026,

    Quantum dynamics and thermodynamics of a Minkowski-Minkowski wormhole

    , Journal of Cosmology and Astroparticle Physics, Vol: 2026

    We consider the path-integral quantization of a minisuperspace cut-and-paste Lorentzian wormhole connecting two Minkowski spacetimes. The dynamics of the throat radius as a function of proper time is governed by a non-polynomial effective action derived by an application of the Israel junction condition formalism. Within a saddle-point approximation of the propagator describing the evolution from an initial to a final throat radius, we show that topology-changing transitions are suppressed by the Hessian determinant. In addition, we analyze the gravitational thermodynamics of the wormhole spacetime by a Wick rotation of the Israel-Lanczos equations in the presence of a thin-shell source. The resulting Euclideanized field equations are assumed to originate from a Euclidean effective gravity-matter action, which enters the path-integral representation of the gravitational canonical partition function. Therefrom we associate a temperature given by the inverse period of solutions, as well as a gravitational entropy as functions of the surface energy density and equation of state parameter of the shell. Both quantities are sourced entirely by the discontinuity of the extrinsic curvature across the junction. We show how this result can be applied to deduce a thermodynamic first law as the differential version of the conservation equation relating the effective mass of the shell to its surface pressure.

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