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## Publications

Publications (60)

We provide the post-Newtonian (PN) waveform for binary systems in motion along generic planar orbits at 2.5PN accuracy, in terms of the dynamical variables of the effective one-body (EOB) formalism. In addition to the calculation of the higher-order terms for all the contributions to the waveform that have been already considered in previous avatar...

General relativity (GR) will be imminently challenged by upcoming experiments in the strong gravity regime, including those testing the energy extraction mechanisms for black holes. Motivated by this, we explore magnetospheric models and black hole jet emissions in MOdified Gravity (MOG) scenarios. Specifically, we construct new power emitting magn...

We provide the post-Newtonian (PN) waveform for binary systems in motion along generic planar orbits at 2.5PN accuracy, in terms of the dynamical variables of the effective one-body (EOB) formalism. In addition to the calculation of the higher order terms for all the contributions to the waveform that have been already considered in previous avatar...

The dynamics of a binary system moving in the background of a black hole is affected by tidal forces. In this work, for the Kerr black hole, we derive the electric and magnetic tidal moments at quadrupole order, where the latter are computed for the first time in full generality. We make use of these moments in the scenario of a hierarchical triple...

The dynamics of a binary system moving in the background of a black hole is affected by tidal forces. In this work, for the Kerr black hole, we derive the electric and magnetic tidal moments at quadrupole order, where the latter are computed for the first time in full generality. We make use of these moments in the scenario of a hierarchical triple...

The Blandford and Znajek (BZ) split-monopole serves as an important theoretical example of the mechanism that can drive the electromagnetic extraction of energy from Kerr black holes. It is constructed as a perturbative low spin solution of Force Free Electrodynamics (FFE). Recently, Armas et al. put this construction on a firmer footing by clearin...

We introduce a new paradigm for constructing accurate analytic waveforms (and fluxes) for eccentric compact binaries. Our recipe builds on the standard post-Newtonian (PN) approach but (i) retains implicit time-derivatives of the phase space variables in the instantaneous part of the noncircular waveform, and then (ii) suitably factorizes and resum...

In this paper, we assess the performances of different analytical prescriptions for the effective-one-body (EOB) radiation reaction along generic planar orbits using exact numerical result in the test-mass limit. We consider three prescriptions put forward in the recent literature: (i) the quasicircular prescription (QC), (ii) the QC with second po...

We present a new approach to factorize and resum the post-Newtonian (PN) waveform for generic equatorial motion to be used within effective-one-body (EOB-)based waveform models. The new multipolar waveform factorization improves previous prescriptions in that (i) the generic Newtonian contribution is factored out from each multipole; (ii) the circu...

We introduce a new paradigm for constructing accurate analytic waveforms (and fluxes) for eccentric compact binaries. Our recipe builds on the standard Post-Newtonian (PN) approach but (i) retains implicit time-derivatives of the phase space variables in the instantaneous part of the noncircular waveform, and then (ii) suitably factorizes and resum...

In this paper we assess the performances of different analytical prescriptions for the effective-one-body (EOB) radiation reaction along generic planar orbits using exact numerical result in the test-mass limit. We consider three prescriptions put forward in the recent literature: (i) the quasi-circular prescription QC, (ii) the QC with 2 post-Newt...

The Blandford and Znajek (BZ) split-monopole serves as an important theoretical example of the mechanism that can drive the electromagnetic extraction of energy from Kerr black holes. It is constructed as a perturbative low spin solution of Force Free Electrodynamics (FFE). Recently, Armas $et~al.$ put this construction on a firmer footing by clear...

We present a new approach to factorize and resum the post-Newtonian (PN) waveform for generic equatorial motion to be used within effective-one-body (EOB) based waveform models. The new multipolar waveform factorization improves previous prescriptions in that: (i) the generic Newtonian contribution is factored out from each multipole; (ii) the circ...

We propose a new approach to find magnetically-dominated force-free magnetospheres around highly spinning black holes, relevant for models of astrophysical jets. Employing the near-horizon extreme Kerr (NHEK) limit of the Kerr black hole, any stationary, axisymmetric and regular force-free magnetosphere reduces to the same attractor solution in the...

A bstract
We obtain a first order post-Minkowskian two-body effective potential whose post-Newtonian expansion directly reproduces the Einstein-Infeld-Hoffmann potential. Post-Minkowskian potentials can be extracted from on-shell scattering amplitudes in a quantum field theory of scalar matter coupled to gravity. Previously, such potentials did not...

We consider force-free magnetospheres around the extreme Kerr black hole. In this case there is no known exact analytic solution to force free electrodynamics which is stationary, axisymmetric and magnetically-dominated. However, any stationary, axisymmetric and regular force-free magnetosphere in extreme Kerr black hole approaches the same attract...

We propose a new approach to find magnetically-dominated force-free magnetospheres around highly spinning black holes, relevant for models of astrophysical jets. Employing the near-horizon extreme Kerr (NHEK) limit of the Kerr black hole, any stationary, axisymmetric and regular force-free magnetosphere reduces to the same attractor solution in the...

We consider force-free magnetospheres around the extreme Kerr black hole. In this case there is no known exact analytic solution to force free electrodynamics which is stationary, axisymmetric and magnetically-dominated. However, any stationary, axisymmetric and regular force-free magnetosphere in extreme Kerr black hole approaches the same attract...

We obtain a first order post-Minkowskian two-body effective potential whose post-Newtonian expansion directly reproduces the Einstein-Infeld-Hoffmann potential. Post-Minkowskian potentials can be extracted from on-shell scattering amplitudes in a quantum field theory of scalar matter coupled to gravity. Previously, such potentials did not reproduce...

Despite their potential importance for understanding astrophysical jets, physically realistic exact solutions for magnetospheres around Kerr black holes have not been found, even in the force-free approximation. Instead approximate analytical solutions such as the Blandford–Znajek (split-)monopole, as well as numerical solutions, have been construc...

Despite their potential importance for understanding astrophysical jets, physically realistic exact solutions for magnetospheres around Kerr black holes have not been found, even in the force-free approximation. Instead approximate analytical solutions such as the Blandford-Znajek (split-)monopole, as well as numerical solutions, have been construc...

The Blandford-Znajek monopole is a conjectured solution of force-free electrodynamics in the vicinity of a slowly rotating Kerr black hole, supposedly defined as a perturbation in small angular momentum. It is used to argue for the extraction of energy from rotating black holes by the Blandford-Znajek process. We set up a careful analysis of the pe...

In this paper we use the effective blackfold description of branes to extend the study of the thermal BIon, a D-brane and parallel anti-D-brane connected by a wormhole with F-string charge in hot flat space, by introducing a radial boost along the brane. The boosted system behaves qualitatively differently from both the extremal and the thermal BIo...

In this paper we formulate a correspondence between four-dimensional Born-Infeld theory and five-dimensional classical gravity. The Born-Infeld theory side corresponds to the low energy effective theory for open strings ending on coincident D3-branes in a (slowly varying) background Kalb-Ramond field, including all higher-derivative corrections. On...

We introduce a new quantum mechanical theory called Spin Matrix theory (SMT). The theory is interacting with a single coupling constant g and is based on a Hilbert space of harmonic oscillators with a spin index taking values in a Lie (super)algebra representation as well as matrix indices for the adjoint representation of U(N). We show that SMT de...

We study the effective action for finite-temperature D3-branes with an
electromagnetic field at weak and strong coupling. We call this action the
thermal DBI action. Comparing at low temperature the leading $T^4$ correction
for the thermal DBI action at weak and strong coupling we find that the $3/4$
factor well-known from the AdS/CFT correspondenc...

We calculate planar, tree-level, non-extremal three-point functions of
operators belonging to the SU(2) x SU(2) sector of ABJM theory. First, we
generalize the determinant representation, found by Foda for the three-point
functions of the SU(2) sector of N=4 SYM, to the present case and find that the
ABJM result up to normalization factors factoriz...

We study the giant graviton solution as the AdS5 × S
5 background is heated up to finite temperature. The analysis employs the thermal brane probe technique based on the blackfold approach. We focus mainly on the thermal giant graviton corresponding to a thermal D3-brane probe wrapped on an S
3 moving on the S
5 of the background at finite temperat...

We apply a new description of thermal fundamental string probes to the study
of finite temperature Wilson loops in the context of the AdS/CFT
correspondence. Previously this problem has been considered using extremal
probes even though the background is at finite temperature. The new description
of fundamental string probes is based on the blackfol...

We explore the recent weak/strong coupling match of three-point functions in
the AdS/CFT correspondence for two semi-classical operators and one light
chiral primary operator found by Escobedo et al. This match is between the
tree-level three-point function with the two semi-classical operators described
by coherent states while on the string side...

We revisit the calculation of curvature corrections to the pp-wave energy of type IIA string states on
$ {\text{Ad}}{{\text{S}}_4} \times \mathbb{C}{P^3} $
initiated in arXiv:0807.1527. Using the near pp-wave Hamiltonian found in arXiv:0912.2257, we compute the first non-vanishing correction to the energy of a set of bosonic string states at orde...

We investigate the thermodynamics of the recently obtained finite temperature
BIon solution of arXiv:1012.1494, focusing on two aspects. The first concerns
comparison of the free energy of the three available phases for the finite
temperature brane-antibrane wormhole configuration. Based on this we propose a
heuristic picture for the dynamics of th...

We revisit the calculation of curvature corrections to the pp-wave energy of
type IIA string states on AdS_4 x CP^3 initiated in arXiv:0807.1527. Using the
near pp-wave Hamiltonian found in arXiv:0912.2257, we compute the first
non-vanishing correction to the energy of a set of bosonic string states at
order 1/R^2, where R is the curvature radius o...

We propose a new method to consider D-brane probes in thermal backgrounds.
The method builds on the recently developed blackfold approach to
higher-dimensional black holes. While D-brane probes in zero-temperature
backgrounds are well-described by the Dirac-Born-Infeld (DBI) action, this
method addresses how to probe thermal backgrounds. A particul...

We find the full interacting Lagrangian and Hamiltonian for quantum strings in a near plane wave limit of AdS4 × $$ \mathbb{C} $$
P
3. The leading curvature corrections give rise to cubic and quartic terms in the Lagrangian and Hamiltonian that we compute
in full. The Lagrangian is found as the type IIA Green-Schwarz superstring in the light-cone g...

We find a new Penrose limit of AdS_5 x S^5 giving the maximally supersymmetric pp-wave background with two explicit space-like isometries. This is an important missing piece in studying the AdS/CFT correspondence in certain subsectors. In particular whereas the Penrose limit giving one space-like isometry is useful for the SU(2) sector of N=4 SYM,...

We consider finite-size corrections in the SU(2)×SU(2) sector of type IIA string theory on AdS4×CP3, which is the string dual of the recently constructed N=6 superconformal Chern–Simons theory of Aharony, Bergman, Jafferis and Maldacena (ABJM theory). The string states we consider are in the R×S2×S2 subspace of AdS4×CP3 with an angular momentum J o...

Using an effective vertex method we explicitly derive the two-loop dilatation generator of ABJM theory in its SU(2) × SU(2) sector, including all non-planar corrections. Subsequently, we apply this generator to a series of finite length operators as well as to two different types of BMN operators. As in Script N = 4 SYM, at the planar level the fin...

We find the exact solution for a finite size Giant Magnon in the SU(2) × SU(2)
sector of the string dual of the = 6 superconformal Chern-Simons theory recently constructed by
Aharony, Bergman, Jafferis and Maldacena. The finite size Giant Magnon solution consists of two
magnons, one in each SU(2). In the infinite size limit this solution correspond...

We identify a regime of the AdS/CFT correspondence in which we can
quantitatively match N=4 super Yang-Mills (SYM) for small 't Hooft coupling
with weakly coupled type IIB string theory on AdS_5 x S^5. We approach this
regime by taking the same decoupling limit on both sides of the correspondence.
On the gauge theory side only the states in the SU(...

We compute higher order finite size corrections to the energies of the circular rotating string on AdS_5 x S^5, of its orbifolded generalization on AdS_5 x S^5/Z_M and of the winding state which is obtained as the limit of the orbifolded circular string solution when J -> infinity and J/M^2 is kept fixed. We solve, at the first order in lambda'=lam...

We examine the string dual of the recently constructed N=6 superconformal Chern–Simons theory of Aharony, Bergman, Jafferis and Maldacena (ABJM theory). We focus in particular on the SU(2)×SU(2) sector. We find a sigma-model limit in which the resulting sigma-model is two Landau–Lifshitz models added together. We consider a Penrose limit for which...

We find new decoupling limits of N=4 super Yang-Mills (SYM) on R x S-3 with gauge group SU(N). These decoupling limits lead to decoupled theories that are much simpler than the full N=4 SYM but still contain many of its interesting features. The decoupling limits correspond to being in a near-critical region, near a point with zero temperature and...

We find new decoupling limits of Script N = 4 super Yang-Mills (SYM) on
Bbb R × S3 with gauge group SU(N). These decoupling
limits lead to decoupled theories that are much simpler than the full
Script N = 4 SYM but still contain many of its interesting features. The
decoupling limits correspond to being in a near-critical region, near a
point with...

We match the Hagedorn/deconfinement temperature of planar N=4 super Yang-Mills (SYM) on R x S^3 to the Hagedorn temperature of string theory on AdS_5 x S^5. The match is done in a near-critical region where both gauge theory and string theory are weakly coupled. On the gauge theory side we are taking a decoupling limit found in hep-th/0605234 in wh...

This article is based on the result obtained in hep-th/0508126 and hep-th/0605080 where we use the IIB light-cone string field theory proposed by Dobashi and Yoneya to compute the one string-loop correction to the energies of two impurity BMN states. We found that the result agrees with the gauge theory prediction at leading order – one-loop in Yan...

We match the Hagedorn/deconfinement temperature of planar N=4 super Yang-Mills (SYM) on RxSÂ³ to the Hagedorn temperature of string theory on AdSâxSâµ. The match is done in a near-critical region where both gauge theory and string theory are weakly coupled. The near-critical region is near a point with zero temperature and critical chemical potent...

We find a decoupling limit of planar N=4 super Yang-Mills (SYM) on R x S^3 in which it becomes equivalent to the ferromagnetic XXX_{1/2} Heisenberg spin chain in an external magnetic field. The decoupling limit generalizes the one found in hep-th/0605234 corresponding to the case with zero magnetic field. The presence of the magnetic field is seen...

We study the thermodynamics of U(N)N=4 super-Yang–Mills (SYM) on R×S3 with non-zero chemical potentials for the SU(4) R-symmetry. We find that when we are near a point with zero temperature and critical chemical potential, N=4 SYM on R×S3 reduces to a quantum mechanical theory. We identify three such critical regions giving rise to three different...

The one string-loop correction to the energies of two impurity BMN states are computed using IIB light-cone string field theory with an improved 3-string vertex that has been proposed by Dobashi and Yoneya. As in previous published computations, the string vertices are truncated to the 2-impurity channel. The result is compared with the prediction...

We investigate the one-loop energy shift E to certain two-impurity string states in light-cone string field theory on a plane wave background. We find that there exist logarithmic divergences in the sums over intermediate mode numbers which cancel between the cubic Hamiltonian and quartic ``contact term''. Analyzing the impurity non-conserving chan...

We study non planar corrections to the spectrum of operators in the
Script N = 2 supersymmetric Yang Mills theory which are dual to string
states in the maximally supersymmetric pp-wave background with a compact
light-cone direction. The existence of a positive definite discrete
light-cone momentum greatly simplifies the operator mixing problem. We...

We compute, on the disk, the non-linear tachyon $\beta$-function, $\beta^T$, of the open bosonic string theory. $\beta^T$ is determined both in an expansion to the third power of the field and to all orders in derivatives and in an expansion to any power of the tachyon field in the leading order in derivatives. We construct the Witten-Shatashvili (...

The thermodynamics of type-IIB superstring theory in the
maximally supersymmetric plane wave background is studied. We compute
the thermodynamic partition function for non-interacting strings
exactly and the result differs slightly from previous computations.
We clarify some of the issues related to the Hagedorn temperature in
the limits of small a...

The appearance of space/time non-commutativity in theories of open strings with a constant non-diagonal background metric is considered. We show that, even if the space-time coordinates commute, when there is a metric with a time-space component, no electric field and the boundary condition along the spatial direction is Dirichlet, a Moyal phase st...

We consider the problem of condensation of open string tachyon fields which have an O(D) symmetric profile. This problem is described by a boundary conformal field theory with D scalar fields perturbed by relevant boundary operators with O(D) symmetry. The model is exactly solvable in the large D limit and we analyze its 1/D expansion. We find that...

The effect of certain simple backgrounds on the Hagedorn temperature in theories of closed strings is examined. The background of interest are a constant Neveu-Schwarz B-field, a constant offset of the space-time metric and a compactified spatial dimension. We find that the Hagedorn temperature of string theory depends on the parameters of the back...

We study the discrete light-cone quantization (DLCQ) of closed strings in the background of Minkowski space-time and a constant Neveu-Schwarz $B$-field. For the Bosonic string, we identify the $B$-dependent part of the thermodynamic free energy to all orders in string perturbation theory. For every genus, $B$ appears in a constraint in the path int...