Gravitational Raman Scattering

• Gravitational Raman scattering is the inelastic scattering of waves off compact objects, where frequency-dependent phase shifts reveal internal gravitational responses.
• It employs worldline EFT and quantum-optical techniques to capture both conservative tidal responses and dissipative effects such as absorption and decoherence.
• Recent findings show running dynamical Love numbers and potential photon–graviton interference signatures, unifying aspects of black hole, neutron star, and GW detection studies.

Searching arXiv for papers on gravitational Raman scattering and closely related work. Gravitational Raman scattering denotes a class of gravitationally mediated inelastic scattering phenomena in which an incident wave probes internal or background gravitational degrees of freedom and acquires a frequency-dependent response analogous to Raman processes in optics. In the recent literature, the term is used in at least three technically distinct but conceptually connected senses: as quasi-elastic scattering of massless fields off compact relativistic objects within worldline EFT (Ivanov et al., 2024, Ivanov et al., 6 Feb 2026); as gravitational-wave scattering off neutron stars with dissipative tidal response and tidal heating (Saketh et al., 2024); and as a fully quantum description of gravitational-wave detection in which a coherent GW background induces Stokes- and anti-Stokes-like photon–graviton scattering sidebands, read out through Hong–Ou–Mandel interference (Hari et al., 28 Jan 2026). Across these settings, the unifying content is that gravitational interaction is treated microscopically or on-shell as a scattering process whose real part encodes conservative tidal response and whose imaginary part encodes dissipation, absorption, or distinguishability.

1. Terminological scope and core definition

In worldline EFT and scattering-amplitude studies, gravitational Raman scattering is defined as the inelastic scattering of massless fields off compact relativistic objects (Ivanov et al., 6 Feb 2026). The external probe may be a scalar, photon, or graviton, while the target is represented by a worldline endowed with internal multipole operators and response functions. In this usage, the analogy to optical Raman scattering lies in the fact that the scattered wave is sensitive to internal structure through frequency-dependent susceptibilities, namely Love and dissipation numbers (Ivanov et al., 2024, Ivanov et al., 6 Feb 2026).

In the scalar EFT formulation, the process is described as quasi-elastic scattering of a massless scalar field off a compact object, where the scalar probes internal multipole degrees of freedom $Q_L$, and the response is encoded in a correlator $F_\ell(\omega)$ whose real part gives conservative Love numbers and whose imaginary part gives dissipation numbers (Ivanov et al., 2024). The scattering is “quasi-elastic” because the incoming wave retains essentially the same frequency up to small corrections, while exchange with internal modes and absorption remain possible.

In neutron-star perturbation theory, the same term refers to gravitational-wave scattering off a neutron star, where the scattering amplitude encodes both the electric quadrupolar static Love number and the leading dissipation number associated with viscous tidal heating (Saketh et al., 2024). Here the emphasis is less on explicit frequency-shifted sidebands and more on the complex response of the star: conservative deformation in the real part, irreversible energy and angular-momentum transfer in the imaginary part.

In the fully quantum optical proposal, the term is used in a more literal Raman sense. A GW is modeled as a coherent graviton background that induces inelastic photon–graviton scattering, producing Stokes- and anti-Stokes-like frequency shifts $\omega \to \omega \pm \omega_{\mathrm{gw}}$ for photons (Hari et al., 28 Jan 2026). The cumulative phase shift measured by interferometry is interpreted as the macroscopic limit of many microscopic inelastic scattering events.

This suggests that “gravitational Raman scattering” is best understood as a family resemblance term rather than a single narrowly fixed mechanism. The common structure is scattering against gravitationally responsive degrees of freedom, with on-shell amplitudes or microscopic Hamiltonians replacing purely geometric descriptions.

2. Microscopic and effective descriptions

A central formulation is the worldline EFT description of compact objects. The bulk action for a scalar probe is

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$

while the compact object is represented by a worldline action

$S = -m\int d\tau + S_{\rm fs},$

with finite-size terms

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$

for scalar scattering (Ivanov et al., 2024). The relevant response function is the time-ordered correlator

$$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$

expanded at low frequency as

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$

The coefficients $C_{\ell,\omega^{2n}}$ are conservative Love numbers, while the coefficients $C_{\ell,\omega^{2n+1}}$ govern dissipation (Ivanov et al., 2024).

A more systematic generalization to spins $F_\ell(\omega)$0 is given by the worldline EFT plus background-field toolkit of (Ivanov et al., 6 Feb 2026). There the compact object carries multipole operators $F_\ell(\omega)$1 coupled to gauge-invariant tidal tensors $F_\ell(\omega)$2. The retarded correlators define response functions

$F_\ell(\omega)$3

with even $F_\ell(\omega)$4 conservative and odd $F_\ell(\omega)$5 dissipative (Ivanov et al., 6 Feb 2026). The conservative low-frequency sector is encoded in local counterterms such as

$F_\ell(\omega)$6

together with analogous electric, magnetic, and tensor operators for photons and gravitons (Ivanov et al., 6 Feb 2026).

The quantum-optical formulation departs from worldline EFT and instead quantizes both photons and gravitons. The total Hamiltonian is split as

$F_\ell(\omega)$7

with interaction

$F_\ell(\omega)$8

where $F_\ell(\omega)$9 is the transverse–traceless metric perturbation and $\omega \to \omega \pm \omega_{\mathrm{gw}}$0 is the electromagnetic stress tensor (Hari et al., 28 Jan 2026). In mode language, the interaction contains both graviton annihilation and creation operators, yielding Stokes-like and anti-Stokes-like channels. The GW is modeled as a coherent state of gravitons peaked at $\omega \to \omega \pm \omega_{\mathrm{gw}}$1, so the classical metric perturbation arises as $\omega \to \omega \pm \omega_{\mathrm{gw}}$2, while the microscopic process still consists of graviton absorption and emission events (Hari et al., 28 Jan 2026).

3. Raman analogy: sidebands, response functions, and inelasticity

The Raman analogy is precise but context-dependent. In the compact-object scattering literature, the analogy concerns internal response rather than necessarily explicit output sidebands. The compact object plays the role of a medium with internal excitations, and the response function acts as a gravitational polarizability. The real part of the response shifts the phase of scattered partial waves, while the imaginary part leads to inelasticity and absorption (Ivanov et al., 2024, Saketh et al., 2024, Ivanov et al., 6 Feb 2026).

For the scalar case, the partial-wave S-matrix is written as

$\omega \to \omega \pm \omega_{\mathrm{gw}}$3

where $\omega \to \omega \pm \omega_{\mathrm{gw}}$4 is the phase shift and $\omega \to \omega \pm \omega_{\mathrm{gw}}$5 is the inelasticity parameter (Ivanov et al., 2024). The Raman-like aspect is encoded in the pair $\omega \to \omega \pm \omega_{\mathrm{gw}}$6: conservative tidal scattering in $\omega \to \omega \pm \omega_{\mathrm{gw}}$7, dissipative or absorptive channels in $\omega \to \omega \pm \omega_{\mathrm{gw}}$8. The explicit EFT result at 3PM includes

$\omega \to \omega \pm \omega_{\mathrm{gw}}$9

with $$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$0 (Ivanov et al., 2024).

For neutron stars, the amplitude language is similar. The exterior Regge–Wheeler solution behaves asymptotically as

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$1

and the partial-wave S-matrix is

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$2

(Saketh et al., 2024). Matching to EFT identifies the electric quadrupolar Love number and the dissipation number through the near-zone tidal S-matrix.

In the photon–graviton picture, the Raman structure is literal. After gauge fixing and mode expansion, the interaction Hamiltonian contains terms corresponding to

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$3

for graviton emission and

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$4

for graviton absorption (Hari et al., 28 Jan 2026). Because $$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$5 for realistic GWs, these are small sidebands. The resulting phase is obtained from the reduced photon density matrix after tracing out the graviton sector. The phase term and decoherence term appear simultaneously: $$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$6 In the weak-field limit the decoherence is negligible, leaving an effectively unitary phase shift (Hari et al., 28 Jan 2026).

A common misconception is that the Raman analogy requires large observable frequency changes analogous to molecular spectroscopy. In most gravitational applications the relevant signature is instead a tiny, frequency-dependent phase shift or small inelasticity, with explicit sidebands either parametrically small or not isolated in the chosen observable (Ivanov et al., 2024, Saketh et al., 2024, Hari et al., 28 Jan 2026).

4. Post-Minkowskian amplitudes, phase shifts, and renormalization

The EFT amplitude program organizes gravitational Raman scattering in a post-Minkowskian expansion. For scalar scattering off compact objects, the dimensionless control parameter is $$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$7, and tidal effects first appear at 3PM in the setup studied in (Ivanov et al., 2024). The 3PM scalar phase shifts include UV-sensitive contributions in the low partial waves: $$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$8 and

$$S_{\rm bulk}=\int d^{4}x\sqrt{-g}\left(\frac{R}{16\pi G} - \frac12 (\partial_\mu \phi)^2\right),$$9

The $S = -m\int d\tau + S_{\rm fs},$0-wave divergence is renormalized by the monopole dynamical Love number $S = -m\int d\tau + S_{\rm fs},$1, while the $S = -m\int d\tau + S_{\rm fs},$2-wave static Love number $S = -m\int d\tau + S_{\rm fs},$3 is a finite matching parameter (Ivanov et al., 2024).

A central result of (Ivanov et al., 2024) is the appearance of two sources of classical RG flow for dynamical Love numbers: a universal running independent of the nature of the compact object, and a self-induced running proportional to the response itself. After renormalization, the general RG equation becomes

$S = -m\int d\tau + S_{\rm fs},$4

The inhomogeneous term exists only for $S = -m\int d\tau + S_{\rm fs},$5 and produces the universal S-wave running (Ivanov et al., 2024).

The broader toolkit paper extends this structure to spin $S = -m\int d\tau + S_{\rm fs},$6 and higher dimensions (Ivanov et al., 6 Feb 2026). It combines worldline EFT, the background field method, a general-dimensional partial-wave formalism, an exponential representation $S = -m\int d\tau + S_{\rm fs},$7, and IBP plus differential equations for loop integrals. In four dimensions, scalar and spin-1 static Love numbers enter at 3PM, while spin-2 tidal operators do not yet contribute through 3PM (Ivanov et al., 6 Feb 2026).

The following table summarizes the roles of the principal recent formulations.

Setting	Probe/target	Principal observable
(Ivanov et al., 2024)	Massless scalar off compact object	Partial-wave phase shifts, inelasticities, RG of Love numbers
(Saketh et al., 2024)	GW off neutron star	$S = -m\int d\tau + S_{\rm fs},$8, $S = -m\int d\tau + S_{\rm fs},$9, tidal heating
(Hari et al., 28 Jan 2026)	Photons in coherent GW background	HOM coincidence modulation via photon–graviton scattering
(Ivanov et al., 6 Feb 2026)	Spin $$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$0 fields off compact object	Gauge-invariant on-shell tidal matching and PM toolkit

The renormalization structure is one of the distinctive features of this literature. Rather than treating Love numbers as purely static asymptotic coefficients, the on-shell EFT approach shows that dynamical Love numbers can run logarithmically and that some static Love coefficients in higher dimensions also run (Ivanov et al., 2024, Ivanov et al., 6 Feb 2026). This reframes gravitational Raman scattering as a setting in which classical tidal observables acquire a nontrivial EFT renormalization group interpretation.

5. Compact objects: black holes, neutron stars, and tidal heating

For black holes, the scalar 3PM matching in (Ivanov et al., 2024) shows that the EFT phase shifts agree exactly with full GR provided the relevant static Love numbers are set to zero. In particular, consistency with the GR result $$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$1 implies

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$2

for a Schwarzschild black hole (Ivanov et al., 2024). Matching the $$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$3-wave determines the leading scalar dynamical Love number,

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$4

which is nonzero and runs (Ivanov et al., 2024).

The more comprehensive on-shell toolkit confirms and generalizes the vanishing of leading static Love numbers in 4D Schwarzschild backgrounds. Matching to BH perturbation theory yields

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$5

for the scalar dipolar static Love number and

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$6

for the electromagnetic static Love numbers (Ivanov et al., 6 Feb 2026). By contrast, the dynamical scalar Love number is nonzero and logarithmically running (Ivanov et al., 6 Feb 2026). For spin-2 perturbations in 4D, no local gravitational tidal operator contributes up to 3PM, consistent with the expectation that leading gravitational Love effects arise only at higher PM order (Ivanov et al., 6 Feb 2026).

For neutron stars, the same framework becomes a probe of microphysics rather than a demonstration of vanishing response. In (Saketh et al., 2024), the worldline EFT response function is written as

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$7

with

$$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$8

The authors solve the interior perturbation problem including viscosity to linear order in frequency and derive exact-in-compactness formulas for $$S_{\rm fs} = \sum_\ell \int d\tau\; Q_L\,\bm{\nabla}_L \phi + S_{\rm fs}^{\rm ct}$$9 and $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$0 in terms of the boundary data $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$1 and $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$2 (Saketh et al., 2024).

A notable structural result is that, for non-barotropic perturbations with slow reactions, the fluid exhibits “adiabatic incompressibility” in the static limit, so bulk viscosity does not contribute at linear order in $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$3 to the master equations. Only shear viscosity appears at this order (Saketh et al., 2024). The leading dissipation number therefore tracks the viscous damping associated with shear. The EFT absorption rate is

$$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$4

linking the imaginary part of the Raman amplitude directly to tidal heating (Saketh et al., 2024).

The same paper estimates the effect on inspiral phasing in the LVK band. For equal-mass binaries, the change in GW cycles is

$$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$5

and explicit EoS-dependent values are reported. For a $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$6 FSU2 binary with $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$7, the magnitude is approximately $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$8 cycles over the band considered, while for more compact stars the effect falls to $$\int dt\,e^{-i\omega t}\,\langle T Q_{L_1}(t)Q_{L_2}(0)\rangle = -i \delta_{L_1L_2} F_\ell(\omega),$$9 cycles (Saketh et al., 2024). The paper states that, for relatively low-compactness, cold neutron stars, tidal heating can be comparable to, or even exceed, other 4PN conservative corrections (Saketh et al., 2024).

6. Quantum-optical detection and the classical limit

The quantum field-theoretic detection proposal in (Hari et al., 28 Jan 2026) reframes interferometric GW response as photon–graviton scattering. In the regime $$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$0, the interaction Hamiltonian simplifies to a forward-scattering form involving the Doppler-shifted graviton frequency

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$1

and a geometric polarization factor $$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$2 (Hari et al., 28 Jan 2026). For a single-photon mode, the induced phase is

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$3

which, under the coherent-state approximation for the GW, becomes

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$4

This is interpreted as the time integral of a tiny inelastic frequency shift (Hari et al., 28 Jan 2026).

The proposed readout uses Hong–Ou–Mandel interference of frequency-entangled photon pairs. If the two arms acquire GW-induced delays $$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$5, the coincidence probability is

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$6

where $$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$7 (Hari et al., 28 Jan 2026). Without GWs and for equal paths, perfect destructive HOM interference gives $$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$8. Photon–graviton scattering introduces frequency-dependent phases, rendering the photons partially distinguishable and lifting the HOM dip. The GW signal is therefore encoded in coincidence-rate modulation rather than single-port intensity (Hari et al., 28 Jan 2026).

The proposal also shows how the microscopic scattering picture recovers the classical optical-path description. The classical geometric-optics delay is

$$F_\ell(\omega) = C_{\ell,\omega^0} + i C_{\ell,\omega} |\omega| + C_{\ell,\omega^2} \omega^2 + \cdots .$$9

and the quantum phase can be recast as

$C_{\ell,\omega^{2n}}$0

which has exactly the same form after identifying the appropriate projection $C_{\ell,\omega^{2n}}$1 (Hari et al., 28 Jan 2026). The paper therefore argues that the standard interferometric phase shift is the macroscopic coherent-state limit of many tiny inelastic photon–graviton scattering events.

A plausible implication is that gravitational Raman scattering provides a conceptual bridge between quantum optics and classical interferometry: it preserves the observed classical response while relocating its microscopic origin from passive propagation in a prescribed metric to explicit field-theoretic scattering.

7. Conceptual significance, ambiguities, and open directions

One major significance of the subject is methodological. The amplitude-based treatment claims to provide a coordinate-, gauge-, and field-redefinition-invariant definition of tidal parameters by matching on-shell amplitudes and phase shifts rather than off-shell potentials or asymptotic metric coefficients (Ivanov et al., 6 Feb 2026). This is presented as resolving ambiguities that affected earlier off-shell matching calculations, especially for dynamical Love numbers (Ivanov et al., 6 Feb 2026). In particular, the 4D dynamical scalar Love number is identified as nonzero and logarithmically running, while the leading static scalar and spin-1 Love numbers vanish fully on-shell (Ivanov et al., 2024, Ivanov et al., 6 Feb 2026).

A second significance is physical unification. The same Raman vocabulary encompasses black-hole absorption, neutron-star tidal heating, and photon–graviton scattering. The objects differ, the probes differ, and the observables differ, but all are organized by complex response functions whose real part controls conservative scattering and whose imaginary part controls dissipation or decoherence (Ivanov et al., 2024, Saketh et al., 2024, Hari et al., 28 Jan 2026, Ivanov et al., 6 Feb 2026).

Several limitations are explicit in the present literature. The PM toolkit is restricted to the small-frequency regime $C_{\ell,\omega^{2n}}$2 and to nonspinning compact objects in the main matching examples (Ivanov et al., 6 Feb 2026). The neutron-star tidal-heating analysis is limited to nonspinning stars, polar $C_{\ell,\omega^{2n}}$3 perturbations, and linear order in $C_{\ell,\omega^{2n}}$4, with frozen-composition, non-barotropic matter and no superfluid or superconducting effects (Saketh et al., 2024). The quantum-optical detection proposal gives scaling arguments rather than a complete feasibility demonstration and acknowledges formidable challenges in phase stability, path control, photon flux, and noise (Hari et al., 28 Jan 2026).

The literature also distinguishes clearly between probing coherent classical backgrounds and detecting individual gravitons. The photon–graviton interference proposal does not aim at single-graviton detection; it assumes an astrophysical GW with huge graviton occupation number and exploits coherent accumulation of phase (Hari et al., 28 Jan 2026). Similarly, the compact-object scattering papers interpret dissipation and response through on-shell amplitudes without requiring direct resolution of internal quanta (Ivanov et al., 2024, Saketh et al., 2024, Ivanov et al., 6 Feb 2026).

Current extensions identified in the literature include higher PM orders, spinning compact objects, higher-dimensional backgrounds, and direct incorporation into inspiral waveform models (Ivanov et al., 2024, Ivanov et al., 6 Feb 2026). In higher dimensions, static Love numbers can run already at low PM order; for example, in $C_{\ell,\omega^{2n}}$5, the spin-2 coefficients obey explicit RG equations at 2PM (Ivanov et al., 6 Feb 2026). This suggests that gravitational Raman scattering is not merely a metaphor for tidal response but a systematic computational framework for organizing finite-size, dissipative, and quantum-interference effects in general relativity and related effective theories.