A microscopic description of absorption in high-energy string-brane collisions

D’Appollonio, Giuseppe; Vecchia, P. Di; Russo, Rodolfo; Veneziano, G.

doi:10.1007/jhep03(2016)030

Cited by 13 publications

(14 citation statements)

References 38 publications

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“…Besides, it appears naturally in studies of the trans-Planckian-energy quantum collision of massless strings among themselves [7] and with branes [8]. In this regime gravity dominates and various CGR results, such as gravitational deflection and tidal excitation, have been reproduced.…”

Section: Introductionmentioning

confidence: 98%

Gravitational radiation from massless particle collisions

Gruzinov

Veneziano

2016

Class. Quantum Grav.

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We compute classical gravitational bremsstrahlung from the gravitational scattering of two massless particles at leading order in the (center of mass) deflection angle θ ∼ 4G √ s/b = 8GE/b ≪ 1.The calculation, although non-perturbative in the gravitational constant, is surprisingly simple and yields explicit formulae -in terms of multidimensional integrals-for the frequency and angular distribution of the radiation. In the range b −1 < ω < (GE) −1 , the GW spectrum behaves like log(1/GEω)dω, is confined to cones of angular sizes (around the deflected particle trajectories) ranging from O(θ) to O(1/ωb), and exactly reproduces, at its lower end, a well-known zero-frequency limit. At ω > (GE) −1 the radiation is confined to cones of angular size of order θ(GEω) −1/2 resulting in a scale-invariant (dω/ω) spectrum. The total efficiency in GW production is dominated by this "high frequency" region and is formally logarithmically divergent in the UV. If the spectrum is cutoff at the limit of validity of our approximations (where a conjectured bound on GW power is also saturated), the fraction of incoming energy radiated away turns out to be 1 2π θ 2 log θ −2 at leading logarithmic accuracy.

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Section: Introductionmentioning

confidence: 98%

Gravitational radiation from massless particle collisions

Gruzinov

Veneziano

2016

Class. Quantum Grav.

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“…This system will be the main subject of our investigations here.In this paper we explore the fuzzball geometries by scattering massless closed string states from the D1/D5 brane system. We will follow closely the approach pioneered by Amati, Ciafaloni and Veneziano for high-energy string scattering in the Regge regime [41]-[44] that has later on been adapted to the study of closedstring scattering off D-branes [45]- [52]. We present three different descriptions of the scattering process.…”

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confidence: 99%

“…The scattering is described by 'ladder' diagrams whose elementary block is the tree-level (disk) string-brane scattering amplitude i.e. the closed string two-point amplitude on the disk [45]- [52]. The deflection angle can be extracted from the phase shift δ(E, b) describing the transition from the incoming to the outgoing asymptotic states 1 e 2i δ(E,b) = 1 + i A(E, b) 2E (1.1) with A(E, b) the Fourier transform of the string theory scattering amplitude.…”

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confidence: 99%

Probing fuzzballs with particles, waves and strings

Bianchi

Consoli

Morales

2018

J. High Energ. Phys.

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We probe D1D5 micro-state geometries with massless particles, waves and strings. To this end, we study geodetic motion, Klein-Gordon equation and string scattering in the resulting gravitational background. Due to the reduced rotational symmetry, even in the simple case of a circular fuzzball, the system cannot be integrated elementarily. Yet, for motion in the plane of the string profile or in the orthogonal plane to it, one can compute the deflection angle or the phase shift and identify the critical impact parameter, at which even a massless probe is captured by the fuzzball if its internal momentum is properly tuned. We find agreement among the three approaches, thus giving further support to the fuzzball proposal at the dynamical level. account for the entropy of 'large' 3-charge black holes in five dimensions, let alone the case of 4-charged black holes in four dimensions.More progress can be achieved by considering 2-charge systems in string theory. Four and five-dimensional 'small' black-holes with two charges can be constructed in string theory in terms of closed oriented fundamental strings carrying Kaluza-Klein momentum [34] (see [35]-[40] for studies of the dynamical properties of these systems). These black holes are not solution of Einstein gravity but of its higher derivative extension, so their horizons are of stringy size. The stringy micro-states can be counted exactly and put in correspondence with regular geometries associated to the U-duality equivalent 2-charge system realised in terms of a bound-state of D1-and D5-branes. In this framework one can find smooth horizonless geometries of Einstein gravity in six dimensions characterised by a string profile function that incarnate the fuzzball paradigm in a fully successful way [5,6,7]. This system will be the main subject of our investigations here.In this paper we explore the fuzzball geometries by scattering massless closed string states from the D1/D5 brane system. We will follow closely the approach pioneered by Amati, Ciafaloni and Veneziano for high-energy string scattering in the Regge regime [41]-[44] that has later on been adapted to the study of closedstring scattering off D-branes [45]- [52]. We present three different descriptions of the scattering process. First we consider the geodetic motion of a massless particle in the fuzzball gravitational background. Second, we consider the 'classical' wave scattering in the fuzzball geometry. Finally, we study the scattering of massless closed string states off the 2-charge D-brane bound-state.In the regime where the impact parameter b is large compared to the typical scale L p of the geometry ('Schwarzschild radius'), the quasi-elastic scattering process is characterised by a small deflection angle θ and it is dominated by soft processes in which a very large number of nearly on-shell gravitons are exchanged between the high-energy string state and the brane. The scattering is described by 'ladder' diagrams whose elementary block is the tree-level (disk) string-brane scattering amplitude ...

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“…This 3D result is interesting, since for higher dimensions causality violations in higher derivative theories were shown to be avoided only with infinitely many massive higher spin states [23], string theory being the unique example [24].…”

Section: Solutions Of the Linearized Equationsmentioning

confidence: 82%

“…Hence all the parentheses should be positive or zero, to have non-ghost excitations and positivity of these terms should not contradict with the positivity of the boundary theory (24). This can be achieved if…”

Section: Solutions Of the Linearized Equationsmentioning

confidence: 99%

Bulk and boundary unitary gravity in 3D:MMG2

Tekin¹

2015

Phys. Rev. D

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We construct a massive spin-2 theory in 2+1 dimensions that is immune to the bulk-boundary unitarity conflict in anti-de Sitter space and hence amenable to holography. The theory is an extension of Topologically Massive Gravity, just like the recently found Minimal Massive Gravity (MMG), but it has two massive helicity modes instead of a single one. The theory admits all the solutions of TMG with a redefined topological parameter. We calculate the Shapiro time-delay and show that flat-space (local) causality is not violated. We show that there is an interesting relation between the theory we present here (which we call MMG2), MMG and the earlier New Massive Gravity (NMG): Namely, field equations of these theories are non-trivially related. We study the bulk excitations and boundary charges of the conformal field theory that could be dual to gravity. We also find the chiral gravity limit for which one of the massive modes becomes massless. The virtue of the model is that one does not have to go to the chiral limit to achieve unitarity in the bulk and on the boundary and the log-terms that appear in the chiral limit and cause instability do not exist in the generic theory.PACS numbers: I. INTRODUCTIONGravity in 2+1 dimensions has a counterintuitive richness: On the one side, naive counting from the metric leads to the conclusion that once gauge invariance (diffeomorphism invariance) is taken into account, no local propagating degrees of freedom (gravitons or gravity waves) exist, as in the case of Einstein's gravity. On the other hand, modifications of the theory, such as with higher powers of curvature introduce non-trivial local dynamics along with, usually, massive gravitons. Therefore, while it is very hard to get non-linear, unitary, ghostfree massive gravity in 3+1 dimensions with 5 degrees of freedom, it is embarrassingly easy to get massive gravity with 2 degrees of freedom in one lower dimensions. By now there there are several 3D models : Topologically Massive Gravity (TMG),[1], New Massive Gravity (NMG) [2] and the recent Minimal Massive Gravity (MMG) [3,4]. TMG is a parity-violating theory with a single spin-2 degree of freedom, NMG has a massive spin-2 excitation with both helicities, while MMG has a single massive parity-violating spin-2 excitation (same as TMG) but free of the bulk-boundary unitarity conflict in anti-de Sitter(AdS)spacetime that inflicts NMG and TMG. Ultimately, of course, research in 3D gravity aims at understanding or building "quantum gravity" in the physically relevant spacetime. For this purpose, obtaining a unitary, nontrivial gravity theory that has a welldefined unitary conformal field theory on the boundary is an important step. For example, NMG which has 2 massive bulk excitations just like General Relativity in 4D (with a massless graviton) does not have a unitary * Electronic address: btekin@metu.edu.tr conformal field theory (CFT) on the boundary. [Elaborate extensions of NMG could not resolve the issue [5,6].] Hence MMG stands alone as a curious non-trivial case of a 3...

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A microscopic description of absorption in high-energy string-brane collisions

Cited by 13 publications

References 38 publications

Gravitational radiation from massless particle collisions

Gravitational radiation from massless particle collisions

Probing fuzzballs with particles, waves and strings

Bulk and boundary unitary gravity in 3D:MMG2

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