In General > s.a. cosmological constant [fat]; gravitational radiation; spin-2 field theories; quantum field theory in curved spacetime.
* Idea: Classically, a solution of the wave equation obtained linearizing the Einstein equation; In quantum theory, a quantum of the spin-2 field obtained linearizing gravity; From the point of view of non-perturbative quantum gravity, gravitons appear as approximations to the deeper fundamental excitations of quantum geometry.
* Reality and detection: Freeman Dyson has questioned whether any conceivable experiment in the real universe can detect a single graviton; If not, is it meaningful to talk about gravitons as physical entities?
@ General references: in Wentzel 49.
@ Non-linear: Penrose GRG(76), GRG(76); Przanowski et al MPLA(98) [and sl(n, \(\mathbb C\)) chiral fields].
@ Related topics: Rothman & Boughn FP(09)gq [reality and detection]; Sokołowski & Staruszkiewicz CQG(06)gq [properties]; Dyson IJMPA(13) [detection]; Gubitosi & Magueijo PRD(17)-a1610 [correlations between right- and left-handed gravitons]; > s.a. particle types [abundance].

In Quantum Gravity > s.a. approaches to quantum gravity [linearized] and connection representation; covariant quantum gravity.
@ Propagator, spin-foam models: Rovelli PRL(06)gq/05; Bianchi et al NPB(09); Miković & Vojinović a1103 [ELPR/FK models and modified vertex amplitudes]; Riello PRD(14) [radiative corrections]; Han et al PRD(18)-a1711 [with cosmological constant]; > s.a. spin-foam models.
@ Propagator: Bianchi et al CQG(06)gq [lqg]; Livine & Speziale JHEP(06)gq [group integral techniques]; Huang & Parker a0705/PRD [in massive gravity theory]; Alesci & Rovelli PRD(07)-a0708, PRD(08)-a0711 [and Barrett-Crane vertex]; Dittrich et al PRD(07)-a0707 [and 4-simplex Regge action]; Alesci IJMPA(08)-a0802-proc; Magliaro & Perini IJMPA(08)-proc [in lqg vs linearized gravity]; Alesci et al CQG(09)-a0812; Faizal CQG(12)-a1112 [in n-dimensional AdS spacetime]; Vereshkov & Marochnik JModP(13)-a1108 [in the Heisenberg representation]; Faizal & Higuchi PRD(12)-a1107 [covariant and physical, in de Sitter spacetime]; Miao et al PRD(14)-a1306 [in de Sitter spacetime]; Rahbardehghan EPJC(15)-a1406 [group-theoretical approach]; Khatsymovsky IJMPA(18)-a1804, Knorr & Schiffer a2105 [non-perturbative]; > s.a. 3D quantum gravity; spin networks.
@ Matter coupling: Bern et al PRL(00) [and strings]; Álvarez & Faedo PRD(07)-a0707.
@ String-inspired: Branson et al IJMPA(00); Giudice et al NPB(05)hp/04 [collider effects with large extra dimensions].
@ Photon-graviton scattering: Källberg et al CQG(06)gq/04; Bjerrum-Bohr et al PRD(15)-a1410; Bartolo et al PRD(18)-a1804.
@ Scattering, other: Dunbar & Norridge CQG(97); Deser et al CQG(99); Bedford et al NPB(05)ht, Cachazo & Svrček ht/05 [tree-level recursion relations]; Holstein AJP(06)nov-gq [interaction with matter]; Vázquez JHEP(09) [in AdS/cft]; Delfino et al JHEP(15)-a1210 [graviton-graviton scattering in the pure connection formalism for gravity]; Boels and Medina PRL(17)-a1607 [gravitons and gluons, from first principles].
@ Self-energy: Grillo CQG(01)ht/99; > s.a. quantum field theory techniques [worldline approach].
@ Related topics: Gould AP(95) [graviton production]; Modanese PLB(95) [lifetime for decay into gravitons]; Boughn & Rothman CQG(06)gq [emission-absorption by H atoms]; Barrau & Grain a0805-proc [lqg propagator in FLRW spacetime, and cosmological perturbations]; Laperashvili MPLA(11)-a1107 [in Plebański formulation, essentially renormalizable]; Bern et al PRD(14)-a1406 [low-enery behavior]; Latosh EPJP-a2005 [mixing of graviton spin states].
> Related topics: see Goldstone Boson; quantum regge calculus.

Other Effects and Related Topics > s.a. branes [dispersion relation]; decoherence; green functions; tests of general relativity.
* Effects of non-zero mass: Corrections of order \((\lambda/\lambda_{\rm Compton}^~)^2\) to graviton propagation, which would lead to dispersion.
* Giant graviton puzzle: The apparent multiplicity of supergravity states dual to field theory chiral primary operators.
@ Early universe: Gershtein et al gq/01; Zee PLB(04)ht/03 [and dark energy]; news nat(13)sep [detecting gravitons in the cmb polarization].
@ Giant graviton: Janssen & Lozano CQG(03) [non-Abelian effective action]; Prokushkin et al JHEP(04) [bound states]; Bena & Smith PRD(05) [re solution].
@ Composite graviton: Moffat gq/03 [and cosmological constant]; Okui PRD(06)hp/05 [and collider physics].
@ Ghost gravitons: Deruelle et al JHEP(12)-a1202 [vs Lorentz-symmetry violation in Weyl gravity, and the spectrum of primordial gravitational waves].
> Other effects: see bose-einstein condensates; dark-energy types [scalar graviton]; Gravitational Memory [soft gravitons].

Mass / Theories with Massive Gravitons > s.a. emergent gravity; massive gravity; newtonian gravity [mass]; Pauli-Fierz Lagrangian.
* Idea: In general relativity gravitational waves travel at the speed of light, and the mass of the graviton is zero; Not so in some modified gravity theories.
* Mass bounds: 2016, \(m < 1.2 \times 10^{-22}\) eV/\(c^2\), from an analysis of the phase of the wave in the first LIGO detection; Gravitational waves and gamma rays from the binary neutron star merger event GW170817 arrived within 1.74 seconds of each other, even after traveling for 120 million years; 2020, \(m < 2 \times 10^{-28}\) eV/\(c^2\), from binary pulsars.
@ General references: van Dam & Veltman GRG(72); Novello & Neves CQG(03)gq/02 [meff in AdS]; Chamseddine ht/04-conf [from spontaneous symmetry breaking]; Gabadadze & Gruzinov PRD(05) [instability of Minkowski]; Dvali et al PRL(08)-a0806 [non-Pauli-Fierz]; Bebronne PhD(09)-a0910 [theory and phenomenology]; Bernard et al a1504 [in an arbitrary curved background]; > s.a. conservation laws.
@ In various theories: Visser GRG(98)gq/97 [gravity with background metric]; Porrati MPLA(03) [from coupling to cft in AdS]; Myung PRD(10)-a0906 [Hořava-Lifshitz gravity]; Capozziello et al IJTP(10)-a1001 [f(R) gravity]; de Roany et al PRD(11)-a1109 [Visser's bimetric theory].
@ And the cosmological constant: Novello IJMPD(04); Metaxas a1010 [from scalar field coupling].
@ And the cmb: Bessada & Miranda CQG(09) [polarization]; Dubovsky et al PRD(10)-a0907 [anisotropy and polarization].
@ And cosmology: Dubovsky JHEP(04), et al PRL(05)ht/04 [as dark matter]; Tajmar CQG(06)gq, Alves et al PLB(11) [and dark energy]; Pshirkov et al PRL(08) [as dark matter, constraints]; Eckhardt et al NA(10)-a0909 [and supernova-Ia and CMB observations]; Alves et al PRD(10)-a1007 [constraints on Visser's model]; Berkhahn et al JCAP(10) [stability of massive cosmological gravitons]; Tsamis & Woodard IJMPD(11)-a1103 [interactions and "cosmological screening", expansion slowdown]; Koyama et al IJMPD(11) [ghost-free theory]; Biermann & Harms a1205 [graviton background as dark energy]; De Felice & Mukohyama PRL(17)-a1607 [m = 9.8 × 10−33 eV/c2 and tension in cosmological data].
@ Mass bounds: Goldhaber & Nieto RMP(10)-a0809; Berti et al PRD(11) [massive black-hole populations]; Farag Ali & Das IJMPD(16)-a1605-GRF [theory]; de Rham et al RMP(17)-a1606 [rev]; Zakharov et al IJMPcs(18)-a1712 [ways to estimate]; Will CQG(18)-a1805 & CQG+ [solar system vs gravitational-wave bounds]; Gupta & Desai AP(18)-a1810 [stacked galaxy cluster catalogs], CQG(19)-a1811 [Chandra X-ray cluster sample]; Perkins & Yunes CQG(19)-a1811 [gravitational-wave propagation, with screening]; Bernus et al PRL(19) [planetary ephemeris]; Shao et al a2007 [binary pulsars].
@ Mass bounds, compact binaries: Will PRD(98)gq/97; Finn & Sutton PRD(02)gq/01; Sutton & Finn CQG(02)gq/01; Larson & Hiscock PRD(00)gq/99; Cutler et al PRD(03) [and LISA]; Jones ApJL(05)gq/04 [eccentric]; Arun & Will CQG(09) [higher harmonics in gravitational-wave templates]; Keppel & Ajith PRD(10)-a1004 [gravitational waves from binary black holes].
@ Other phenomenology: de Paula et al CQG(04)gq [wave polarization states]; Brandt et al PLA(08) [inside a superconductor, in terms of fundamental constants]; Momeni a0903-wd [and bending of light]; > s.a. black-hole hair; gravitational radiation.

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