Quantum-Gravity Phenomenology  

In General > s.a. approaches; effective theories; quantum gravity [including experiment, philosophy] and canonical quantum gravity; quantum spacetime.
* Idea: The identification of quantum properties of spacetime which might give rise to observably large effects.
* Types and examples: Theoretically, some predictions are geometric (like black hole area quantization, with ΔAmin ~ 4 ln2 lP2), others concern the behavior of matter (like photon propagation); Phenomenologically, some predict systematic shifts in observed quantities, others new fundamental uncertanties; 2015, The most promising context in which to look for effects may be cosmology, with imprints on the cmb.
* Scale: 1996, Bound is 10−19 m, from p-pbar collisions at Fermilab (no internal structure in quarks at that level), and p decay experiments have in effect probed smaller scales [@ news pn(96)dec]; 2008, Non-observation of small black holes produced by cosmic rays implies a model-independent lower bound of 488 GeV.
@ I / II: Amelino-Camelia pw(03)nov; Smolin PT(06)nov.
@ Reviews: Amelino-Camelia MPLA(02)gq-conf, a0806; Hossenfelder & Smolin PiC(10)-a0911-in; Hossenfelder a1010-conf; Barrau & Grain a1206-GRF; Girelli et al Sigma(12)-a1210 [lqg]; Amelino-Camelia LRR(13); Barrau & Grain a1410-ch [lqg]; Hossenfelder ed-18.
@ General references: Wheeler IJMPA(93); Salopek IJMPD(94); Smolin gq/95; Ashtekar PRL(96)gq [large effects]; Ahluwalia ChJP(97)gq [non-locality, free-fall, etc]; Amelino-Camelia MPLA(98)gq, LNP(00)gq/99-proc, Nat(01)gq, ap/02-ln [gamma and cosmic rays], et al APP(03)gq/02 [particle production]; Ashtekar mp/02-proc; Ahluwalia MPLA(02)gq-conf; Ng MPLA(03)gq, LNP(05)gq/04, NCB(05); Giulini et al ed-03; Amelino-Camelia GRG(04)ap/03 [in space], LNP(05)gq/04, et al AIP(05)gq [strategy]; Aloisio et al gq/04-MGX, NCB(05)ap-conf; Kimberly & Magueijo AIP(05)gq; Corichi & Sudarsky IJMPD(05)gq [new scheme]; Ahluwalia-Khalilova CQG(05)ht; Sudarsky IJMPD(05)gq; Smolin in(09)gq/06; Hossenfelder AIP(07)ht/06; Das & Vagenas PRL(08)-a0811 [universality of corrections]; Bonder & Sudarsky RPMP(09)-a0811, Bonder a1104-conf, a1204-conf [respecting Lorentz symmetry]; Liberati & Maccione JPCS(11)-a1105; Amelino-Camelia et al PRD(13) [physical characterization]; Bruneton a1308 [model-independent laws]; Fewster & Liberati GRG(14)-a1402 [GR20 report]; Marletto & Vedral a1704 [witnessing non-classicality indirectly]; Bonder a1704-proc [framework]; Loret et al a1805-MG14; Wüthrich a1902 [3 approaches].
@ In modified theories: Arzano et al PRD(15)-a1412 [with anti-de Sitter momentum space].
@ Against the idea: Mohrhoff MPLA(02)qp [quantum-gravity phenomenology = "contradiction in terms", only hep cutoff].

Effects at Different Scales > s.a. Chandrasekhar Limit; GUTs.
* Mesoscopic scales: At scales close but somewhat larger than Planck length, one could describe quantum spacetime and matter in terms of an effective geometry, where propagators for matter fields get corrections from the existence of a zero-point or minimal length and by matter self-gravity.
@ General references: Ne'eman PLA(94) [mass and localizability]; Dvali et al PRD(02) [as low as 10−3 eV]; Anchordoqui et al PRD(03)hp; Kazakov IJMPD(03)ht; Hong & Hsu PLB(04)hp/03 [brane world]; Han & Willenbrock PLB(05) [radiative corrections and new physics at 1018 GeV]; Calmet & Hsu PLB(08)-a0711, Calmet & Feliciangeli PRD(08)-a0806 [energy scale in 4D]; Dvali & Gómez PLB(09)-a0812 [theories with N species, and information]; Frampton CQG(09) [and black-hole formation]; Panković a0901 [from microscopic black holes]; Borowiec et al EPL(10)-a0912 [constraints from κ-Minkowski spacetime]; Barceló et al FP(11)-a1002 [two distinct energy scales]; Atkins & Calmet EPJC(10)-a1005 [and unitarity]; Adler AJP(10)sep [elementary arguments]; Adler a1110 [gravitational fine-structure constant]; Olmo JCAP(11) [invariant and universal length scale]; Nozari et al EPL(15)-a1512 [bounds from QCD]; Arzano & Calcagni a1604 [GW150914, gravity waves]; Chang et al a1605-GRF; Singh a1704-GRF [Compton-Schwarzschild length]; Bonder et al PRD(17)-a1704 [polymer scale and GRBs]; Bodendorfer et al a1902 [the Hamiltonian as a polymerisation parameter]; Padmanabhan a2005 [mesoscopic scales]; Lake a2005-GRF [quantum of action for geometry].
@ Planck scale: Meschini FS(07)gq/06 [significance]; Giddings AIP(09)-a0910 [beyond]; Basilakos et al JCAP(10)-a1009 [effects]; Faraoni AJP(17)nov-a1705 [heuristic derivations]; Doplicher et al a1911 [at the big bang, effective].
@ Low-energy description: Ivanov a0706-conf; Nomura et al PLB(14)-a1304 [and complementarity]; Donoghue & Holstein JPG(15)-a1506 [from effective field theory]; Battista a1606-PhD [and high-energy limits].

Spacetime Measurements and Minimal Length > s.a. DSR; modified lorentz symmetry.
* Idea: Quantum uncertainties in the metric limit spacetime measurements, modify uncertainty relations and, from hoop-conjecture-type arguments, have often been used to argue for the existence of a fundamental minimal length (for example, the time of an event cannot be determined with accuracy better than σt /t = a0 (tP/t)a, for some a0, a ~ 1); The latter in turn has been used as motivation for modified dispersion relations, or a modified action of the Lorentz group (as in DSR).
@ Limitations: Salecker & Wigner PR(58); in Misner et al 73, 1190ff; Padmanabhan CQG(87); Mashhoon PLA(90); Wheeler PRD(90); Schön gq/93; Amelino-Camelia MPLA(94)gq/96, MPLA(96)gq, PLB(97)gq/96, PLB(00)gq/99; Ng & Van Dam MPLA(94); Jaekel & Reynaud PLA(94)qp/98, QSO(95)qp; Baez & Olson CQG(02)gq, comment Ng & van Dam CQG(03)gq/02; Calmet et al PRL(04)ht, IJMPD(05)ht-GRF; Lloyd qp/05-wd [covariant, from computation]; Galán & Mena PRD(05)gq [from DSR]; Calmet EPJC(08)ht/07-proc, MPLA(07)-a0704-proc; Amelino-Camelia & Stachel GRG(09)-a0710; Requardt a0807 [closer inspection]; Hossenfelder CQG(12)-a1205, comment Doplicher et al a1206; Lloyd a1206 [quantum geometric limit]; Burderi et al PRD(16)-a1603 [limits on time measurements]; Maziashvili a1908.
@ Minimal length: Heisenberg ZP(43); Garay IJMPA(95)gq/94; Hinrichsen & Kempf JMP(96)ht/95; Padmanabhan PRL(97)ht/96 [duality]; Amelino-Camelia AIP(01)gq; Chang ht/04-conf; Hossenfelder MPLA(04)hp [and large extra dimensions]; Ahluwalia-Khalilova IJMPD(05)ht [from stabilized Poincaré-Heisenberg algebra]; Hossenfelder CQG(06)ht/05 [consistency of approaches]; Schiller IJTP(06); Maziashvili hp/06; Klinkhamer JETPL(07)gq [different from Planck length]; Kempf PRL(09)-a0908 [natural ultraviolet cutoff]; Martinetti et al RVMP(12)-a1106 [in non-commutative geometry]; Sprenger et al EJP(12)-a1202 [intro]; Hossenfelder LRR(13)-a1203; Kothawala PRD(13)-a1307; Farag Ali & Majumder EPJC(21)-a2104 [from anisotropic spin-orbit interaction]; > s.a. asymptotic safety; deformation quantization; effects on matter; Hausdorff Dimension; poincaré group [deformed]; world function.
@ Minimal length and string theory: Veneziano EPL(86); Gross & Mende NPB(88); Amati et al PLB(89); Konishi et al PLB(90); Aspinwall NPB(94)ht [strings].
@ Minimal length and quantum field theory: Brustein et al PRD(02)ht/00; Lieu ApJL(02)ap [hep]; Hossenfelder PRD(06)ht [interpretation]; Campo a1004 [problems with causality and/or unitarity]; Basu & Mattingly PRD(10)-a1006 [closer look at handwaving arguments]; Cunliff CQG(12)-a1201 [conformal fluctuations and lower bound on proper lengths]; Doplicher et al JGP(13)-a1201 [event localization in semiclassical gravity]; Amadei et al a1912 [unitarity and information, example]; > s.a. types of quantum field theories.
@ Lorentz invariance: Rovelli & Speziale PRD(03)gq, Livine & Oriti JHEP(04)gq [discrete]; Alfaro et al PRD(04) [lqg, variables].
@ Minimum time: Itzhaki PLB(94)ht; Barbero et al PRD(04)gq/03 [non-perturbative model]; El Dahab & Tawfik CJP(14)-a1401; Wendel et al PRL(20)-a2005 + news sn(20)jul.
@ Simultaneity: Kok et al qp/02 [distributed entanglement].

Other Effects and Applications
> Specific issues and topics: see Anyons; causality violations; constants; Correspondence Principle; deformed and entropic uncertainty relations; entanglement and gravity; entanglement phenomenology; entropy bound; neutrinos [masses]; observables; parity [violation]; Planck's Constant.
> Experiments: see quantum gravity [proposed non-classicality tests]; SAGE.
> In related areas: see cosmology [including cosmological singularities]; gravitation and astrophysics; photons; particle properties and matter in general; quantum computing; spacetime foam; spacetime geometry [including metric fluctuations, gravitational collapse, other singularities, volume and chaos].

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