Twistors| Twistors |
In General > s.a. complex structures.
$ Twistor space: The space
of pairs (ωA,
πA ') of a spinor
and a complex conjugate spinor; It has 8 (or in some versions 6) dimensions.
$ Projective twistor space: The
space PT of equivalence classes of twistors (under multiplication by a non-zero
complex number) is \(\mathbb C\)P3, the space of
all lines through the origin in \(\mathbb C\)4.
$ Null twistors:
The ones that satisfy ωA
π*A
+ ω*A'
πA' = 0;
They correspond to null lines in Minkowski space.
* Graphic representation: A non-null
twistor can be sketched as a series of nested doughnuts of various sizes travelling
at the speed of light along their shared axis, a Robinson congruence.
* Relationships: Notice that each
line in PT induces a line in \(\mathbb H\)2,
i.e., an element of \(\mathbb H\)P1 ≅
S7/SU(2) ≅ S4;
In fact, \(\mathbb C\)P3 is a bundle over
S4, with fiber \(\mathbb C\)P1
≅ S2.
* And Minkowski space:
To construct PT one can complexify \(\mathbb C\) and then take lines through the
origin, or compactify M to S4, and then
consider the S2-bundle over S4.
@ References: Penrose JMP(67);
Penrose IJTP(68),
in(81) [curved spacetime];
Woodhouse CQG(85);
Bandyopadhyay & Ghosh IJMPA(89);
Penrose in(99),
GRG(06);
Atiyah et al PRS(17)-a1701 [history].
And Physics
> s.a. angular momentum [at null infinity]; locality [relative
locality]; loop quantum gravity and spin-foam models.
* Idea: One replaces
Minkowski space M by PT, and then translates problems on
M to problems on PT; The basic objects here are null lines;
A null geodesic in Minkowski is a null projective twistor, points are
intersections of null lines or 2-spheres of null projective twistors.
* Motivation: Twistors
incorporate the concepts of energy, momentum and spin, and this allows
them to work as basic building blocks to describe everything; They also
allow quantum fluctuations to set in at the very basic level of definition
of points; Null lines can fluctuate, causal relations are more basic.
* Twistor equation:
∂AA' ωB = −i εAB πA' .
* Applications: Maxwell's
equations and some components of the Einstein equation come out very naturally,
and twistors are used to find solutions of Yang-Mills and Einstein's equations.
* Twistor graphs: The analog
of Feynman graphs; It seems that they should be always finite; In fact each
one could correspond to (infinitely?) many Feynman diagrams.
@ Particles: Fedoruk & Zima ht/02-conf [twistorial superparticle],
JKU(03)ht,
ht/04-proc [spinning];
Bars & Picón PRD(06)ht/05,
PRD(06);
Mezincescu et al JPA(16)-a1508 [massive supersymmetric particle];
> s.a. spinning particles.
@ Gravity: Brody & Hughston AIP(05)ht [quantum spacetime];
Speziale EPJWC(14)-a1404 [loop quantum gravity, and time];
Herfray JMP-a1610 [twistor action].
@ Twistor strings:
Cachazo & Svrček PoS-ht/05;
Musser SA(10)jun;
> s.a. spacetime foam; string theory.
@ Related topics:
Penrose CQG(97) [and light rays];
Cederwall PLB(00) [in anti-de Sitter spacetime];
Sinkovics & Verlinde PLB(05) [6D N = 4 super-Yang-Mills];
Wolf JPA(10)-a1001-ln [and supersymmetric gauge theories];
Dalhuisen & Bouwmeester JPA(12) [and knotted electromagnetic fields];
Livine et al PRD(12) [twistor networks];
Metzner CQG(13),
CQG(13) [higher-dimensional black holes];
Lukierski & Woronowicz IJMPA-a1311-conf [quantization, and non-commutative spacetime].
General References > s.a. Hyperkähler Structure.
@ And mathematics: Atiyah & Ward CMP(77).
@ Textbooks and reviews:
Penrose & MacCallum PRP(73);
Penrose in(75);
Sparling in(75);
Hughston 79;
Madore et al PRP(79) [intro];
Penrose in(80);
Penrose & Ward in(80); Ward in(81);
Huggett IJTP(85);
Ward & Wells 90;
Huggett & Tod 94;
Esposito 95;
Penrose CQG(99)A;
Bars ht/06-ln;
Adamo a1712-ln [intro].
@ Proceedings, collections: Huggett ed-94.
@ Symplectic twistor spaces:
Vaisman JGP(86).
@ Twistor-spinors: Lichnerowicz LMP(89);
Hayashi MPLA(01)ht [spin-3/2].
@ Twistor conformal field theory:
Hodges, Penrose & Singer PLB(89).
@ Generalizations: Hannabuss LMP(01)ht [non-commutative (Moyal) deformation];
da Rocha & Vaz PoS-mp/04;
Baird & Wehbe CMP(11) [on a finite graph];
Lin & Zheng a1609 [higher-dimensional].
@ Related topics: Low JMP(90) [causal geometry];
Field & Low JGP(98) [linking];
Zunger PRD(00) [on coset spaces];
Frauendiener & Sparling JMP(00) [local twistors and conformal field equations];
Ilyenko JMP(02)ht/01 [representation of null 2-surfaces];
Chamblin CQG(04)ht [and holographic bound];
Arcaute et al mp/06 [and Clifford algebra];
Bloch a1302 [twistor integrals];
> s.a. loop space.
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