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Journal articleCabass G, Jazayeri S, Pajer E, et al., 2023,
Parity violation in the scalar trispectrum: nogo theorems and yesgo examples
, The Journal of High Energy Physics, Vol: 2023, ISSN: 10298479We derive a set of nogo theorems and yesgo examples for the parityodd primordial trispectrum of curvature perturbations. We work at treelevel in the decoupling limit of the Effective Field Theory of Inflation and assume scale invariance and a BunchDavies vacuum. We show that the parityodd scalar trispectrum vanishes in the presence of any number of scalar fields with arbitrary mass and any parityodd scalar correlator vanishes in the presence of any number of spinning fields with massless de Sitter mode functions, in agreement with the findings of Liu, Tong, Wang and Xianyu [1]. The same is true for correlators with an odd number of conformallycoupled external fields. We derive these results using both the (boostless) cosmological bootstrap, in particular the Cosmological Optical Theorem, and explicit perturbative calculations. We then discuss a series of yesgo examples by relaxing the above assumptions one at the time. In particular, we provide explicit results for the parityodd trispectrum for (i) violations of scale invariance in singleclock inflation, (ii) the modified dispersion relation of the ghost condensate (nonBunchDavies vacuum), and (iii) interactions with massive spinning fields. Our results establish the parityodd trispectrum as an exceptionally sensitive probe of new physics beyond vanilla inflation.

Journal articleGeorgousi M, Karnesis N, Korol V, et al., 2023,
Gravitational waves from double white dwarfs as probes of the milky way
, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 519, Pages: 25522566, ISSN: 00358711 Author Web Link
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 Citations: 5

Journal articleIsichei R, Magueijo J, 2023,
Minisuperspace quantum cosmology from the EinsteinCartan path integral
, Physical Review D, Vol: 107, Pages: 18, ISSN: 24700010We derive the fixedΛ and unimodular propagators using the path integral formalism as applied to the EinsteinCartan action. The simplicity of the action (which is linear in the lapse function) allows for an exact integration starting from the lapse function and the enforcement of the Hamiltonian constraint, leading to a product of ChernSimons states if the connection is fixed at the endpoints. No saddle point approximation is needed. Should the metric be fixed at the endpoints, then, depending on the contour chosen for the connection, HartleHawking or Vilenkin propagators are obtained. Thus, in this approach one trades a choice of contour in the lapse function for one in the connection, where appropriate. The unimodular propagators are also trivial to obtain via the path integral, and the previously derived expressions are recovered.

Journal articleChester SM, 2023,
Bootstrapping 4d $$ \mathcal{N} $$ = 2 gauge theories: the case of SQCD
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>We derive exact relations between certain integrals of the conserved flavor current four point function in 4d <jats:inlineformula><jats:alternatives><jats:texmath>$$ \mathcal{N} $$</jats:texmath><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math></jats:alternatives></jats:inlineformula> = 2 conformal field theories (CFTs) and derivatives of the mass deformed sphere free energy, which can be computed exactly for gauge theories using supersymmetric localization. For conformal gauge theories with flavor groups of rank greater than one, there are at least two such integrated constraints, which can then be combined with the numerical conformal bootstrap to bound CFT data as a function of the complexified gauge coupling <jats:italic>τ</jats:italic>. We apply this strategy to the case of SU(2) conformal SQCD with flavor group SO(8), where we compute bounds on unprotected scaling dimensions as a function of <jats:italic>τ</jats:italic> that match the free theory limit, and exhibit the expected mixing between the action of the SL(2<jats:italic>,</jats:italic> ℤ) duality group and SO(8) triality.</jats:p>

Journal articleGielen S, Magueijo J, 2023,
Quantum analysis of the recent cosmological bounce in the comoving Hubble length
, Physical Review D, Vol: 107, Pages: 116, ISSN: 24700010We formulate the transition from decelerated to accelerated expansion as a bounce in connection space and study its quantum cosmology, knowing that reflections are notorious for bringing quantum effects to the fore. We use a formalism for obtaining a time variable via the demotion of the constants of nature to integration constants, and focus on a toy universe containing only radiation and a cosmological constant Λ for simplicity. We find that, beside the usual factorordering ambiguities, there is an ambiguity in the order of the quantum equation, leading to two distinct theories: one second order, and one first order. In both cases two time variables may be defined, conjugate to Λ and the radiation constant of motion. We make little headway with the secondorder theory, but are able to produce solutions to the firstorder theory. They exhibit the wellknown “ringing” whereby incident and reflected waves interfere, leading to oscillations in the probability distribution even for wellpeaked wave packets. We also examine in detail the probability measure within the semiclassical approximation. Close to the bounce, the probability distribution becomes double peaked, with one peak following a trajectory close to the classical limit but with a Hubble parameter slightly shifted downwards, and the other with a value of b stuck at its minimum. An examination of the effects still closer to the bounce, and within a more realistic model involving matter and Λ, is left to future work.

Journal articleBeccaria M, Korchemsky GP, Tseytlin AA, 2023,
Exact strong coupling results in <i>N</i>=2 Sp(2<i>N</i>) superconformal gauge theory from localization
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 10298479 Author Web Link
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 Citations: 4

Journal articleChester SM, Dempsey R, Pufu SS, 2023,
Bootstrapping $$ \mathcal{N} $$ = 4 superYangMills on the conformal manifold
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>We combine supersymmetric localization results with numerical bootstrap techniques to compute upper bounds on the lowlying CFT data of <jats:inlineformula><jats:alternatives><jats:texmath>$$ \mathcal{N} $$</jats:texmath><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math></jats:alternatives></jats:inlineformula> = 4 superYangMills theory as a function of the complexified gauge coupling <jats:italic>τ</jats:italic>. In particular, from the stress tensor multiplet fourpoint function, we extract the scaling dimension of the lowestlying unprotected scalar operator and its OPE coefficient. While our method can be applied in principle to any gauge group <jats:italic>G</jats:italic>, we focus on <jats:italic>G</jats:italic> = SU(2) and SU(3) for simplicity. At weak coupling, the upper bounds we find are very close to the corresponding fourloop results. We also give preliminary evidence that these upper bounds become small islands under reasonable assumptions.</jats:p>

Journal articleCable A, Rajantie A, 2022,
Secondorder stochastic theory for selfinteracting scalar fields in de Sitter spacetime
, PHYSICAL REVIEW D, Vol: 106, ISSN: 24700010 Author Web Link
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 Citations: 2

Journal articleAfshordi N, Magueijo J, 2022,
Lower bound on the cosmological constant from the classicality of the early Universe
, Physical Review D, Vol: 106, Pages: 110, ISSN: 24700010We use the quantum unimodular theory of gravity to relate the value of the cosmological constant, Λ, and the energy scale for the emergence of cosmological classicality. The fact that Λ and unimodular time are complementary quantum variables implies a perennially quantum Universe should Λ be zero (or, indeed, fixed at any value). Likewise, the smallness of Λ puts an upper bound on its uncertainty, and thus a lower bound on the unimodular clock’s uncertainty or the cosmic time for the emergence of classicality. Far from being the Planck scale, classicality arises at around 7×1011 GeV for the observed Λ, and taking the region of classicality to be our Hubble volume. We confirm this argument with a direct evaluation of the wave function of the Universe in the connection representation for unimodular theory. Our argument is robust, with the only leeway being in the comoving volume of our cosmological classical patch, which should be bigger than that of the observed last scattering surface. Should it be taken to be the whole of a closed Universe, then the constraint depends weakly on Ωk: for −Ωk<10−3, classicality is reached at >4×1012 GeV. If it is infinite, then this energy scale is infinite, and the Universe is always classical within the minisuperspace approximation. It is a remarkable coincidence that the only way to render the Universe classical just below the Planck scale is to define the size of the classical patch as the scale of nonlinearity for a red spectrum with the observed spectral index ns=0.967(4) (about 1011 times the size of the current Hubble volume). In the context of holographic cosmology, we may interpret this size as the scale of confinement in the dual 3D quantum field theory, which may be probed (directly or indirectly) with future cosmological surveys.

Journal articlede Rham C, Engelbrecht L, Heisenberg L, et al., 2022,
Positivity bounds in vector theories
, The Journal of High Energy Physics, Vol: 86, Pages: 140, ISSN: 10298479Assuming unitarity, locality, causality, and Lorentz invariance of the, otherwise unknown, UV completion, we derive a new set of constraints on the effective field theory coefficients for the most general, ghostfree Generalized Proca and Proca Nuevo massive vector models. For the Generalized Proca model, we include new interactions that had not been previously considered in the context of positivity bounds and find these additional terms lead to a widened parameter space for the previously considered interactions. Although, the Generalized Proca and Proca Nuevo models are inequivalent, we find interesting analogues between the coefficients parameterizing the two models and the roles they play in the positivity bounds.

Journal articleArun KG, Belgacem E, Benkel R, et al., 2022,
New horizons for fundamental physics with LISA
, LIVING REVIEWS IN RELATIVITY, Vol: 25, ISSN: 23673613 Author Web Link
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 Citations: 40

Journal articleGonzalez MC, de Rham C, Pozsgay V, et al., 2022,
Causal effective field theories
, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 106, Pages: 125, ISSN: 15502368Physical principles such as unitarity, causality, and locality can constrain the space of consistent effective field theories (EFTs) by imposing twosided bounds on the allowed values of Wilson coefficients. In this paper, we consider the bounds that arise from the requirement of low energy causality alone, without appealing to any assumptions about UV physics. We focus on shiftsymmetric theories, and consider bounds that arise from the propagation around both a homogeneous and a spherically symmetric scalar field background. We find that low energy causality, namely the requirement that there are no resolvable time advances within the regime of validity of the EFT, produces twosided bounds in agreement with compact positivity constraints previously obtained from 2→2 scattering amplitude dispersion relations using full crossing symmetry.

Journal articleAlday LF, Chester SM, 2022,
Pure Anti–de Sitter Supergravity and the Conformal Bootstrap
, Physical Review Letters, Vol: 129, ISSN: 00319007 
Journal articleAlbertini E, Alexander S, Herczeg G, et al., 2022,
Torsion and the probability of inflation
, Journal of Cosmology and Astroparticle Physics, Vol: 2022, Pages: 114, ISSN: 14757516We revisit the problem of the "probability of inflation" from the point of view of the EinsteinCartan theory, where torsion can be present offshell even in the absence of spinorial currents. An informal estimate suggests that the barrier for tunneling from "nothing" into a classical universe becomes thinner and lower, should torsion be present, even if only offshell. We perform a detailed calculation that supports this informal estimate for the case of torsion eigenstates. Finally, we impose a quantum mechanical analog of the zerotorsion condition by restricting to states for which the expectation value of the torsion vanishes. An explicit family of such states is obtained by building wavepackets from linear superpositions of torsion eigenstates with Gaussian weights centered around zero torsion. The tunneling probability for these wave packets is maximized when the variance of the torsion goes to zero. Hence, by considering these wavepackets as the physical states, we recover a sensible model of quantum cosmology that incorporates quantum fluctuations in the torsion, despite the apparently unacceptable conclusions one draws from naïvely considering the tunneling probabilities for the torsion eigenstates.

Journal articleAlday LF, Chester SM, Raj H, 2022,
Mtheory on AdS4 × S7 at 1loop and beyond
, Journal of High Energy Physics, Vol: 2022<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>We study graviton scattering on <jats:italic>AdS</jats:italic><jats:sub>4</jats:sub><jats:italic>× S</jats:italic><jats:sup>7</jats:sup>, which is dual to the stress tensor multiplet fourpoint function in the maximally supersymmetric 3d U(<jats:italic>N</jats:italic>)<jats:sub>1</jats:sub><jats:italic>×</jats:italic> U(<jats:italic>N</jats:italic>)<jats:sub><jats:italic>−</jats:italic>1</jats:sub> ABJM theory. We compute 1loop corrections to this holographic correlator coming from Witten diagrams with supergravity <jats:italic>R</jats:italic> and higher derivative <jats:italic>R</jats:italic><jats:sup>4</jats:sup> vertices, up to contact term ambiguities, and find that the flat space limit matches the corresponding terms in the 11d Mtheory Smatrix. We then use supersymmetric localization to show that all the 1loop contact terms vanish, as was previously observed for the <jats:italic>AdS</jats:italic><jats:sub>4</jats:sub><jats:italic>× S</jats:italic><jats:sup>7</jats:sup><jats:italic>/</jats:italic>ℤ<jats:sub>2</jats:sub> theory dual to U(<jats:italic>N</jats:italic>)<jats:sub>2</jats:sub><jats:italic>×</jats:italic> U(<jats:italic>N</jats:italic>)<jats:sub><jats:italic>−</jats:italic>2</jats:sub> ABJM. Finally, we use the recent localization results of Gaiotto and Abajian, as inspired by twisted Mtheory, to compute all the short OPE coefficients in correlators of the stress tensor multiplet and the next lowest halfBPS operator, which we find saturate the bootstrap bounds on these mixed correlators for all <jats:ital

Journal articleHanany A, Sperling M, 2022,
Magnetic quivers and negatively charged branes
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 10298479 Author Web Link
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 Citations: 3

Journal articleFilippini JP, Gambrel AE, Rahlin AS, et al., 2022,
InFlight Gain Monitoring of SPIDER's TransitionEdge Sensor Arrays
, JOURNAL OF LOW TEMPERATURE PHYSICS, Vol: 209, Pages: 649657, ISSN: 00222291 Author Web Link
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 Citations: 1

Journal articleBartolo N, Bertacca D, Caldwell R, et al., 2022,
Probing anisotropies of the Stochastic Gravitational Wave Background with LISA
, Journal of Cosmology and Astroparticle Physics, Vol: 2022, ISSN: 14757516We investigate the sensitivity of the Laser Interferometer Space Antenna (LISA) to the anisotropies of the Stochastic Gravitational Wave Background (SGWB). We first discuss the main astrophysical and cosmological sources of SGWB which are characterized by anisotropies in the GW energy density, and we build a SignaltoNoise estimator to quantify the sensitivity of LISA to different multipoles. We then perform a Fisher matrix analysis of the prospects of detectability of anisotropic features with LISA for individual multipoles, focusing on a SGWB with a powerlaw frequency profile. We compute the noise angular spectrum taking into account the specific scan strategy of the LISA detector. We analyze the case of the kinematic dipole and quadrupole generated by Doppler boosting an isotropic SGWB. We find that β ΩGW ∼ 2 × 1011 is required to observe a dipolar signal with LISA. The detector response to the quadrupole has a factor ∼ 103 β relative to that of the dipole. The characterization of the anisotropies, both from a theoretical perspective and from a mapmaking point of view, allows us to extract information that can be used to understand the origin of the SGWB, and to discriminate among distinct superimposed SGWB sources.

Journal articleHull C, 2022,
Gravity, duality and conformal symmetry
, PROCEEDINGS OF THE ROYAL SOCIETY AMATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 478, ISSN: 13645021 
Journal articleKurlyand SA, Tseytlin AA, 2022,
Type IIB supergravity action on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>M</mml:mi><mml:mn>5</mml:mn></mml:msup><mml:mo>×</mml:mo><mml:msup><mml:mi>X</mml:mi><mml:mn>5</mml:mn></mml:msup></mml:math> solutions
, Physical Review D, Vol: 106, ISSN: 24700010 
Journal articlePieroni M, Ricciardone A, Barausse E, 2022,
Detectability and parameter estimation of stellar origin black hole binaries with next generation gravitational wave detectors
, SCIENTIFIC REPORTS, Vol: 12, ISSN: 20452322 Author Web Link
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 Citations: 7

Journal articleKurlyand SA, Tseytlin AA, 2022,
Type IIB supergravity action on M5 x X5 solutions
, PHYSICAL REVIEW D, Vol: 106, ISSN: 24700010 Author Web Link
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 Citations: 3

Journal articleRoberts MM, Wiseman T, 2022,
Reply to"Comment on 'Curvedspace Dirac description of elastically deformed monolayer graphene is generally incorrect'"
, PHYSICAL REVIEW B, Vol: 106, ISSN: 24699950 Author Web Link
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 Citations: 1

Journal articleMagueijo J, 2022,
Connection between cosmological time and the constants of nature
, PHYSICAL REVIEW D, Vol: 106, Pages: 116, ISSN: 24700010We examine in greater detail the proposal that time is the conjugate of the constants of nature. Fundamentally distinct times are associated with different constants, a situation often found in “relational time” settings. We show how in regions dominated by a single constant the Hamiltonian constraint can be reframed as a Schrödinger equation in the corresponding time, solved in the connection representation by outgoingonly monochromatic plane waves moving in a “space” that generalizes the ChernSimons functional (valid for the equation of state w=−1) for other w. We pay special attention to the issues of unitarity and the measure employed for the inner product. Normalizable superpositions can be built, including solitons, “lightrays” and coherent/squeezed states saturating a Heisenberg uncertainty relation between constants and their times. A healthy classical limit is obtained for factorizable coherent states, both in monofluid and multifluid situations. For the latter, we show how to deal with transition regions, where one is passing on the baton from one time to another, and investigate the fate of the subdominant clock. For this purpose minisuperspace is best seen as a dispersive medium, with packets moving with a group speed distinct from the phase speed. We show that the motion of the packets’ peaks reproduces the classical limit even during the transition periods, and for subdominant clocks once the transition is over. Deviations from the coherent/semiclassical limit are expected in these cases, however. The fact that we have recently transitioned from a decelerating to an accelerating Universe renders this proposal potentially testable, as explored elsewhere.

Journal articleArav I, Gauntlett JP, Roberts MM, et al., 2022,
LeighStrassler compactified on a spindle
, The Journal of High Energy Physics, Vol: 2022, Pages: 147, ISSN: 10298479We construct a new class of supersymmetric AdS3 × Y7 solutions of type IIB supergravity, where Y7 is an S5 fibration over a spindle, which are dual to d = 2, N = (0, 2) SCFTs. The solutions are constructed in a subtruncation of D = 5, SO(6) maximal gauged supergravity and they all lie within the antitwist class. We show that the central charge computed from the gravity solutions agrees with an anomaly polynomial calculation associated with compactifying the N = 1, d = 4 LeighStrassler SCFT on a spindle.

Journal articleMantziris A, Markkanen T, Rajantie A, 2022,
The effective Higgs potential and vacuum decay in Starobinsky inflation
, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 14757516 Author Web Link
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 Citations: 1

Journal articleBeccaria M, Korchemsky GP, Tseytlin A, 2022,
Strong coupling expansion in <i>N</i>=2 superconformal theories and the Bessel kernel
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 10298479 Author Web Link
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 Citations: 6

Journal articleFigueroa DG, Florio A, Loayza N, et al., 2022,
Spectroscopy of particle couplings with gravitational waves
, PHYSICAL REVIEW D, Vol: 106, ISSN: 24700010 Author Web Link
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 Citations: 3

Journal articleAlexandre B, Magueijo J, 2022,
Possible quantum effects at the transition from cosmological deceleration to acceleration
, Physical Review D, Vol: 106, Pages: 113, ISSN: 24700010The recent transition from decelerated to accelerated expansion can be seen as a reflection (or “bounce”) in the connection variable, defined by the inverse comoving Hubble length (b=˙a, on shell). We study the quantum cosmology of this process. We use a formalism for obtaining relational time variables either through the demotion of the constants of nature to integration constants, or by identifying fluid constants of motion. We extend its previous application to a toy model (radiation and Λ) to the realistic setting of a transition from dust matter to Λ domination. In the dust and Λ model two time variables may be defined, conjugate to Λ and to the dust constant of motion, and we work out the monochromatic solutions to the Schrödinger equation representing the Hamiltonian constraint. As for their radiation and Λ counterparts, these solutions exhibit “ringing,” whereby the incident and reflected waves interfere, leading to oscillations in the amplitude. In the semiclassical approximation we find that, close to the bounce, the probability distribution becomes double peaked, one peak following a trajectory close to the classical limit but with a Hubble parameter slightly shifted downwards, the other with a value of b stuck at its minimum b=b⋆. Still closer to the transition, the distribution is better approximated by an exponential distribution, with a single peak at b=b⋆, and a (more representative) average b biased towards a value higher than the classical trajectory. Thus, we obtain a distinctive prediction for the average Hubble parameter with redshift: slightly lower than its classical value when z≈0, but potentially much higher than the classical prediction around z∼0.64, where the bounce most likely occurred. The implications for the “Hubble tension” have not escaped us.

Journal articleLeung R, Stelle KS, 2022,
Supergravities on branes
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 10298479
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