String Theory Phenomenology |

**Particle Physics in General** > s.a. axions; CPT symmetry;
GUTs; higher-spin fields; neutrino;
yang-mills theory.

* __Idea__: The lowest excited modes
of open strings correspond to massless spin-1 particles (the photon, \(W^\pm\), \(Z\)
and gluons); Those of closed strings are massless spin-2 particles (the graviton).

* __Enhançon__:
A hypersurface (spherical in the initial proposal), apparently made of *D*-branes,
which arises in string theory studies of large-*N* SU(*N*) pure gauge
theories with eight supercharges.

@ __General references__: Faraggi ht/97-proc,
ht/99-proc;
Quevedo NPPS(98)hp/97;
Ibáñez CQG(00)hp/99-proc;
Sudarsky et al PRD(03) [bounds from low-energy data];
Dine PT(07)dec [rev];
Antoniadis IJMPA(10) [rev];
Ibáñez a1204-ln [rev];
Ibáñez & Uranga 12;
Faraggi a1404-conf;
Kane IJMPA(15) [how to make contact with the 4D world];
Kane a1601 [string theory is testable];
Quevedo a1612-conf.

@ __And QCD__: Aharony ht/02-ln;
Evans pw(03)may;
Mateos CQG(07)-a0709-ln;
Lüst IJMPA(10).

@ __And gauge theory__: Polyakov NPPS(98)ht/97 [confinement],
IJMPA(99);
Ghilencea & Groot Nibbelink CQG(03) [corrections to couplings];
Imeroni PhD(03)ht;
Sugimoto & Takahashi JHEP(04)ht [and QED];
Caselle et al JHEP(05)hl [Nambu-Goto string and interquark potential];
Heckman CP(10) [F-theory GUTs and experiment].

@ __Accelerator physics__: Dudas & Mourad NPB(00)ht/99;
Antoniadis & Benakli IJMPA(00),
Antoniadis IJMPA(06)in [also branes];
Distler et al PRL(07)hp/06
+ sr(07)jan [prediction and falsifiability in W-boson scattering];
Anchordoqui et al NPB(09);
Anchordoqui et al PRD(14)-a1407 [hadron colliders].

@ __Enhançon__: Jarv & Johnson PRD(00)ht;
Johnson PRD(01)ht/00;
Astefanesei & Myers JHEP(02)ht/01,
Dyson et al JHEP(02)ht/01 [non-spherical];
Merlatti NPB(02)ht/01 [fractional branes].

**And Gravity** > s.a. brane world; covariant quantum
gravity and other approaches; quantum-gravity phenomenology.

* __Idea__: While the matter content
of the theory is dependent on the compactification, in string theory the presence of
gravity in the spectrum is universal; General relativity is recovered in the sense
of an effective interaction between strings in scattering processes; Early suggestions
were from Scherk & Schwarz &(74) and Yoneya &(74); The first correction
to the action for general relativity is a Gauss-Bonnet term; String theory yields
ultraviolet finite scattering amplitudes in theories of gravity coupled to matter.

* __Questions__: Get black holes
(and black-hole evaporation); Planck-scale behavior (Are there singular solutions?
Are they generic? Singularity theorems?).

* __Problem__: Conformal ambiguity in
the physical metric.

* __Black-hole information paradox__: It is
resolved by the picture of quantum black-hole microstates as horizon-sized objects called
'fuzzballs' instead of vacuum regions with a central singularity; Causality requires that
the wavefunctional has an important component not present in the semiclassical picture,
virtual fuzzballs; The large mass of the fuzzballs suppresses their virtual fluctuations,
but this suppression is compensated by the large number exp\([S_{\rm B}(M)]\) of possible
fuzzballs, which are extended compression-resistant objects; The presence of these objects
in the vacuum wavefunctional alters the physics of collapse when a horizon is about to form,
avoiding the information paradox; > s.a. Fuzzballs.

@ __Books, reviews__: Giddings hp/05-ln;
Yoneya a0901-ch [hist, 1969-1974];
Blau & Theisen GRG(09) [open questions];
Elvang & Horowitz a1311-ch;
Ortín 15.

@ __General references__:
Boulware & Deser PRL(85);
Sannan PRD(86);
Banks & Lykken NPB(90);
Smolin gq/96;
Branson et al PLB(97)ht/96;
Porrati LMP(99) [and general relativity];
Green CQG(99)A;
Aharony et al PRP(00) [and large-*N* field theories];
Wessling & Wise PLB(01)ht;
Polyakov IJMPA(02)ht/01 [thoughts];
Siegel ht/03 [weakening at short scales];
Horowitz NJP(05)gq/04 [spacetime];
Arkani-Hamed et al JHEP(07)ht/06 [string landscape and quantum gravity];
Roberts ht/06 [unified field theory];
Damour & Lilley a0802-ln;
Wadia a0809-in [rev, semi-technical];
Deo et al G&C(09) [quantum gravity];
Basu CQG(16)
+ CQG+ [one-loop gravitational interactions].

@ __Gravitational waves__:
Brustein ht/96 [background];
Allen & Brustein PRD(97)gq/96 [and LIGO];
Ungarelli & Vecchio AIP(00)gq/99;
Cartier et al NPB(01) [string cosmology].

@ __Black holes__: Gimon & Hořava PLB(09)-a0706 [superspinning, violating the Kerr bound];
Mathur a1812-proc [virtual fuzzballs];
> s.a. quantum black holes.

@ __Solutions__: Coley PRL(02) [vanishing curvature invariants];
Petri gq/04 [holographic];
Hernández et al G&C(09) [stationary axisymmetric];
> s.a. black holes.

@ __Supergravity__: Witten NPB(95)ht;
Aspinwall NPPS(96)ht/95;
Stelle ht/05-proc [divergence structure];
Deo IJMPA(06)ht/05 [derivation];
Gaillard a1602-in;
Reid-Edwards & Riccombeni JHEP(17)-a1701 [superstring field theory].

> __Related topics__: see corrections
to newtonian gravity; graviton; quantum spacetime;
spacetime; schwarzschild spacetime;
uncertainty.

**Astrophysics and Other Areas** > s.a. anthropic
principle; string cosmology.

* __Landscape__: The name
refers to a plot shaped like a mountainous landscape, where altitude represents
the cosmological constant, with its value settling on a low point somewhere between
the peaks of the landscape; But there could be on the order of 10^{500} possible
such low points, and no obvious reason for the universe to pick the one we observe;
Seen either as a virtue (e.g., in parallel worlds scenarios) or as a sign of
inability to make predictions.

@ __General references__: Kane PT(97)feb;
Musser SA(02)oct;
Gates PT(06)jun;
editorial pw(07)sep;
Kane PT(10)nov.

@ __Astronomy / astrophysics__: Mavromatos JPCS(09)-a0903 [high-energy gamma rays];
Ellis et al a1810 [D-particles and the hydrogen 21-cm line].

@ __Applications to other areas__:
Borsten et al PRL(10)
+ wired(10)sep
[and four-qubit entanglement classification];
McGreevy Phy(10)
+ nat(10)oct [strange metals];
> s.a. condensed matter physics.

@ __Landscape__:
Quevedo pw(03)nov;
Bousso & Polchinski SA(04)sep;
Douglas ht/06-conf;
Schellekens phy/06 [general audience];
Conlon CP(06);
Acharya & Douglas ht/06 [finite?];
Rej a0909-FQXi [decidability, computability and complexity];
Smolin FP(13)-a1202 [historical roots and speculative scenarios];
Banks a1208.

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