We infer the collapse times of long-lived neutron stars into black holes using the x-ray afterglows of 18 short gamma-ray bursts. We then apply hierarchical inference to infer properties of the neutron star equation of state and dominant spin-down mechanism. We measure the maximum non-rotating neutron star mass $M_{\mathrm{TOV}}=2.31_{-0.21}^{+0.36}{M}_{\odot }$ and constrain the fraction of remnants spinning down predominantly through gravitational-wave emission to $\eta =0.69_{-0.39}^{+0.21}$ with 68% uncertainties. In principle, this method can determine the difference between hadronic and quark equation of states. In practice, however, the data is not yet informative with indications that these neutron stars do not have hadronic equation of states at the $1\sigma$ level. These inferences all depend on the underlying progenitor mass distribution for short gamma-ray bursts produced by binary neutron star mergers. The recently announced gravitational-wave detection of GW190425 suggests this underlying distribution is different from the locally measured population of double neutron stars. We show that $M_{\mathrm{TOV}}$ and $\eta$ constraints depend on the fraction of binary mergers that form through a distribution consistent with the locally measured population and a distribution that can explain GW190425. The more binaries that form from the latter distribution, the larger $M_{\mathrm{TOV}}$ needs to be to satisfy the x-ray observations. Our measurements above are marginalized over this unknown fraction. If instead, we assume GW190425 is not a binary neutron star merger, i.e., the underlying mass distribution of double neutron stars is the same as observed locally, we measure $M_{\mathrm{TOV}}=2.26_{-0.17}^{+0.31}{M}_{\odot }$.

We study the static responses of cold quark matter in the intermediate baryonic density region (characterized by a chemical potential $\mu$) in the presence of a strong-magnetic field. We consider in particular, the so-called magnetic dual Chiral Density Wave (MDCDW) phase, which is materialized by an inhomogeneous condensate formed by a particle-hole pair. It is shown, that the MDCDW phase is more stable in the weak-coupling regime than the one considered in the magnetic catalysis of chiral symmetry braking phenomenon and even than the chiral symmetric phase that was expected to be realized at sufficiently high baryonic chemical potential. The different components of the photon polarization operator of the MDCDW phase in the one-loop approximation are calculated. We found that in the MDCDW phase there is neither Debye screening nor Meissner effect in the lowest-Landau-level approximation. The obtained Debye length depends on the amplitude $m$ and modulation $b$ of the inhomogeneous condensate and it is only different from zero if the relation $|\mu -b|>m$ holds. But, we found that in the region of interest this inequality is not satisfied. Thus, no Debye screening takes place under those conditions. On the other hand, since the particle-hole condensate is electrically neutral, the U(1) electromagnetic group is not broken by the ground state and consequently there is no Meissner effect. These results can be of interest for the astrophysics of neutron stars.

Recent global fits to short-baseline neutrino oscillation data have been performed finding preference for a sterile neutrino solution ($3+1$) over null. In the most recent iteration, it was pointed out that an unstable sterile neutrino ($3+1+\text{decay}$) may be a better description of the data. This is due to the fact that this model significantly reduces the tension between appearance and disappearance datasets. In this work, we add a 1-year IceCube dataset to the global fit obtaining new results for the standard $3+1$ and $3+1+\text{decay}$ sterile neutrino scenarios. We find that the $3+1+\text{decay}$ model provides a better fit than the $3+1$, even in the presence of IceCube, with reduced appearance to disappearance tension. The $3+1+\text{decay}$ model is a $5.4\sigma$ improvement over the null hypothesis and a $2.8\sigma$ improvement over the standard $3+1$ model.

We study the nature of the finite temperature phase transition for three-flavor QCD. In particular we investigate the location of the critical endpoint along the three flavor symmetric line in the light quark mass region of the Columbia plot. In the study, the Iwasaki gauge action and the nonperturvatively O($a$) improved Wilson-Clover fermion action are employed. We newly generate data at $N_{\mathrm{t}}=12$ and set an upper bound of the critical pseudoscalar meson mass in the continuum limit $m_{\mathrm{PS},\mathrm{E}}\lesssim 110\mathrm{MeV}$.

We consider the one-parameter family of jet substructure observables known as angularities using the specific case of inclusive jets arising from photoproduction events at an Electron-Ion Collider (EIC). We perform numerical calculations at next-to-leading logarithmic accuracy within perturbative QCD and compare our results to pythia 6 predictions. Overall, we find good agreement and conclude that jet substructure observables are feasible at the EIC despite the relatively low jet transverse momentum and particle multiplicities. We investigate the size of subleading power corrections relevant at low energies within the Monte Carlo setup. In order to establish the validity of the Monte Carlo tune, we also perform comparisons to jet shape data at HERA. We further discuss detector requirements necessary for angularity measurements at an EIC, focusing on hadron calorimeter energy and spatial resolutions. Possible applications of precision jet substructure measurements at the EIC include the tuning of Monte Carlo event generators, the extraction of nonperturbative parameters and studies of cold nuclear matter effects.

We study the effect of shear and bulk viscosities on the heavy quark transport coefficient within the matrix model of semi-QGP. Dissipative effects are incorporated through the first-order viscous correction in the quark/antiquark and gluon distribution function. It is observed that while the shear viscosity effects reduce the drag of heavy quark the bulk viscosity effects increase the drag and the diffusion coefficients of heavy quark. For finite values of $\eta /s$ and $\xi /s$, the Polyakov loop further decreases the drag coefficient and enhances the momentum diffusion coefficient as compared to perturbative QCD. It is also observed that with increases in $\eta /s$ and $\xi /s$ spatial diffusion coefficient decreases.

We consider deep inelastic scattering (DIS) on a dense nucleus described as an extremal RN-AdS black hole with holographic quantum fermions in the bulk. We evaluate the 1-loop fermion contribution to the R-current on the charged black hole, and map it on scattering off a Fermi surface of a dense and large nucleus with fixed atomic number. Near the black hole horizon, the geometry is that of ${\mathrm{AdS}}_2\times {\mathrm{R}}^3$ where the fermions develop an emergent Fermi surface with anomalous dimensions. DIS scattering off these fermions yields to anomalous partonic distributions mostly at large-x, as well as modified hard scattering rules. The pertinent R-ratio for the black hole is discussed. For comparison, the structure functions and the R-ratio in the probe or dilute limit with no backreaction on the geometry, are also derived. We formulate a hybrid holographic model for DIS scattering on heavy and light nuclei, which compares favorably to the existing data for Pb, Au, Fe, C, and He over a wide range of parton-x.

We consider deep inelastic scattering (DIS) on a large nucleus described as an extremal Reissner-Nordström-AdS black hole using the holographic principle. Using the R-current correlators we determine the structure functions as a function Bjorken-x, and map it on a finite but large nucleus with fixed atomic number. The R-ratios of the nuclear structure functions exhibit strong shadowing at low-x.

Superconformal matter multiplets play a crucial role in the construction of Poincaré supergravity invariants. Off-shell multiplets allow for construction of general matter couplings in supergravity. In [P. S. Howe, K. S. Stelle, and P. K. Townsend, Nucl. Phys. B214, 519 (1983)], relaxed hypermultiplet was constructed in rigid supersymmetry which on coupling with the real scalar multiplet allowed for an off-shell formulation of the rigid hypermultiplet. In this paper, we extend the relaxed hypermultiplet to conformal supergravity. For consistency with the superconformal algebra, we find that the fields have to be allowed to transform in a noncanonical way under $SU(2)$ $R$-symmetry. We find suitable field redefinitions to obtain fields which are irreducible representations of $SU(2)$ $R$-symmetry and present the full nonlinear transformation rule.

We investigate the relation between the time-ordered vacuum correlation functions for interacting real scalar fields in Minkowski spacetime and in the Rindler wedge. The correlation functions are constructed perturbatively within the in-in formalism, often employed in calculations in more general spacetimes. We prove to all orders in perturbation theory that the time-ordered vacuum correlation functions can be calculated in the in-in formalism with internal vertices restricted to any Rindler wedge containing the external points. This implies that the Minkowski in-in (or in-out) perturbative expansion of the vacuum correlation functions is reproduced by the Rindler in-in perturbative expansion of these correlators in a thermal state at the Unruh temperature.

We construct a consistent model of Galileon scalar electrodynamics. The model satisfies three essential requirements: (i) The action contains higher-order derivative terms and obeys the Galilean symmetry, (ii) equations of motion also satisfy Galilean symmetry and contain only up to second-order derivative terms in the matter fields and, hence, do not suffer from instability, and (iii) local $U(1)$ gauge invariance is preserved. We show that the nonminimal coupling terms in our model are different from that of the real scalar Galileon models; however, they match with the Galileon real scalar field action. We show that the model can lead to an accelerated expansion in the early Universe. We discuss the implications of the model for cosmological inflation.

The advent of gravitational wave observation starts a new era of precision tests of gravitational theory. Estimates of black hole mergers should come from any well established gravitational theories, provided that the theory has not been ruled out by observations. We consider the low energy limit of heterotic string theory where the associated rotating and charged black holes are described by the Kerr-Sen solution. We investigate the approximate final spins and quasinormal modes of the black hole resulting from the merger process.

When dealing with highly accurate modeling of time and frequency transfers into arbitrarily moving dielectrics medium, it may be convenient to work with Gordon’s optical spacetime metric rather than the usual physical spacetime metric. Additionally, an accurate modeling of the geodesic evolution of observable quantities (e.g., the range and the Doppler) requires us to know the reception or the emission time transfer functions. In the physical spacetime, these functions can be derived to any post-Minkowskian orders through a recursive procedure. In this work, we show that the time transfer functions can be determined to any order in Gordon’s optical spacetime as well. The exact integral forms of the gravitational, the refractive, and the coupling contributions are recursively derived. The expression of the time transfer function is given within the postlinear approximation assuming a stationary optical spacetime covered with geocentric celestial reference system coordinates. The light-dragging effect due to the steady rotation of the neutral atmosphere of the Earth is found to be at the threshold of visibility in many experiments involving accurate modeling of the time and frequency transfers.

We show that Wang’s proof of uniqueness of anti–de Sitter spacetime can be adapted to provide uniqueness results for strictly static asymptotically locally hyperbolic vacuum metrics with toroidal infinity, and to prove negativity of the free energy $E-TS$ of static asymptotically AdS black holes with toroidal or higher-genus horizons.

In the context of the two-body problem in general relativity, hereditary terms in the long range gravitational field depend on the history rather than the instantaneous state of the source at retarded time. We compute the next-to leading effects of such hereditary terms, that comprise tail and memory, on the two-body dynamics, within effective field theory methods, including both dissipative and conservative effects. The former confirm known results at 2.5 post-Newtonian order with respect to the leading order in the luminosity function; the conservative part is a new result and is an unavoidable ingredient for a derivation of the conservative two-body dynamics at fifth post-Newtonian order.

The Earth’s geoid is one of the most essential and fundamental concepts to provide a gravity field-related height reference in geodesy and associated sciences. To keep up with the ever-increasing experimental capabilities and to consistently interpret high-precision measurements without any doubt, a relativistic treatment of geodetic notions (including the geoid) within Einstein’s theory of general relativity is inevitable. Building on the theoretical construction of isochronometric surfaces and the so-called redshift potential for clock comparison, we define a relativistic gravity potential as a generalization of (post-)Newtonian notions. This potential exists in any stationary configuration with rigidly corotating observers, and it is the same as realized by local plumb lines. In a second step, we employ the gravity potential to define the relativistic geoid in direct analogy to the Newtonian understanding. In the respective limit, the framework allows to recover well-known (post-) Newtonian results. For a better illustration and proper interpretation of the general relativistic gravity potential and geoid, some particular examples are considered. Explicit results are derived for exact vacuum solutions to Einstein’s field equation as well as a parametrized post-Newtonian model. Comparing the Earth’s Newtonian geoid to its relativistic generalization is a very subtle problem, but of high interest. An isometric embedding into Euclidean three-dimensional space is an appropriate solution and allows a genuinely intrinsic comparison. With this method, the leading-order differences are determined, which are at the mm level.

Within the standard effective field theory of general relativity, we show that the speed of gravitational waves deviates, ever so slightly, from luminality on cosmological and other spontaneously Lorentz-breaking backgrounds. This effect results from loop contributions from massive fields of any spin, including Standard Model fields, or from tree level effects from massive higher spins $s\ge 2$. We show that for the choice of interaction signs implied by $S$-matrix and spectral density positivity bounds suggested by analyticity and causality, the speed of gravitational waves is in general superluminal at low energies on null energy condition preserving backgrounds, meaning gravitational waves travel faster than allowed by the metric to which photons and Standard Model fields are minimally coupled. We show that departure of the speed from unity increases in the IR and argue that the speed inevitably returns to luminal at high energies as required by Lorentz invariance. Performing a special tuning of the effective field theory so that renormalization sensitive curvature-squared terms are set to zero, we find that finite loop corrections from Standard Model fields still lead to an epoch dependent modification of the speed of gravitational waves which is determined by the precise field content of the lightest particles with masses larger than the Hubble parameter today. Depending on interpretation, such considerations could potentially have far-reaching implications on light scalar models, such as axionic or fuzzy cold dark matter.

Ultralight scalars, if they exist as theorized, could form clouds around rapidly rotating black holes. Such clouds are expected to emit continuous, quasimonochromatic gravitational waves that could be detected by LIGO and Virgo. Here we present results of a directed search for such signals from the Cygnus X-1 binary, using data from Advanced LIGO’s second observing run. We find no evidence of gravitational waves in the 250–750 Hz band. Without incorporating existing measurements of the Cygnus X-1 black hole spin, our results disfavor boson masses in the range $5.8\le \mu /({10}^{-13}\mathrm{eV})\le 8.6$, assuming that the black hole was born $5\times {10}^6\mathrm{years}$ ago with a nearly extremal spin. We then focus on a string axiverse scenario, in which self-interactions enable a cloud for high black-hole spins consistent with measurements for Cygnus X-1. In that model, we constrain the boson masses in the range $9.6\le \mu /({10}^{-13}\mathrm{eV})\le 15.5$ for a decay constant $f_a\sim {10}^{15}\mathrm{GeV}$. Future applications of our methods to other sources will yield improved constraints.

After reminding of properties of the condensate of the complex scalar field in the external uniform magnetic field $H$, focus is made on the study of phases of the complex neutral vector-boson fields coupled with magnetic field by the Zeeman coupling and phases of the charged vector-boson fields. The systems may behave as nonmagnetic and ferromagnetic superfluids and ordinary and ferromagnetic superconductors. Response of these superfluid and superconducting systems occupying half of space on the external uniform static magnetic field $H$ is thoroughly studied. Then the spin-triplet pairing of neutral fermions at conserved spin is considered. Novel phases are found. In external magnetic field, the phase with zero mean spin proves to be unstable to the formation of a phase with a nonzero spin. For a certain parameter choice ferromagnetic superfluid phases are formed already for $H=0$, characterized by an own magnetic field $h$. For $H>H_{\mathrm{cr}2}$, the spin-triplet pairing and ferromagnetic superfluidity continue to exist above the “old” phase transition critical temperature $T_{\mathrm{cr}}$. Formation of domains is discussed. Next, spin-triplet pairing of charged fermions is studied. Novel phases are found. Then, the $3{\mathrm{P}}_2$ $nn$ pairing in neutron star matter is studied. Also, a $3{\mathrm{P}}_2$ $pp$ pairing is considered. Numerical estimates are performed in the BCS weak-coupling limit and beyond it for the $3P_2$ $nn$ and $pp$ pairings, as well as for the $3{\mathrm{S}}_1$ $np$ pairing.

In this work we investigate the implication of $K\to \pi \nu \overline{\nu }$ from the recent KOTO and NA62 measurements for generic neutrino interactions and the new physics scale in effective field theories. The interactions between quarks and left-handed Standard Model (SM) neutrinos are first described by the low energy effective field theory (LEFT) below the electroweak scale. We match them to the chiral perturbation theory ($\chi \mathrm{PT}$) at the chiral symmetry breaking scale to calculate the branching fractions of Kaon semi-invisible decays and match them up to the SM effective field theory (SMEFT) to constrain new physics above the electroweak scale. In the framework of effective field theories, we prove that the Grossman-Nir bound is valid for both dim-6 and dim-7 LEFT operators, and the dim-6 vector and scalar operators dominantly contribute to Kaon semi-invisible decays based on LEFT and chiral power counting rules. They are induced by multiple dim-6 lepton-number-conserving operators and one dim-7 lepton-number-violating operator in the SMEFT, respectively. In the lepton-number-conserving $s\to d$ transition, the $K\to \pi \nu \overline{\nu }$ decays provide the most sensitive probe for the operators with $\tau \tau$ component and point to a corresponding new physics scale of ${\mathrm{\Lambda }}_{\mathrm{NP}}\in [47\mathrm{TeV},72\mathrm{TeV}]$ associated with a single effective coefficient. The lepton-number-violating operator can also explain the observed $K\to \pi \nu \overline{\nu }$ discrepancy with the SM prediction within a narrow range ${\mathrm{\Lambda }}_{\mathrm{NP}}\in [19.4\mathrm{TeV},21.5\mathrm{TeV}]$, which is consistent with constraints from kaon invisible decays.