**Topics, Y**

**Yamabe Flow**
> see ADM mass.

**Yamabe Invariant**

@ __References__: Botvinnik & Rosenberg JDG(02) [non-simply-connected manifolds];
Avila & Dain CQG(08) [axisymmetric initial data of two Kerr black holes].

**Yamabe Question**

@ __Solution__: Schoen JDG(84).

**Yang-Baxter Equation**
> s.a. integrable systems; lie algebras.

* __Idea__: A relationship
between elementary braids in the braid group with *n* strands.

* __Remark__: The solutions of
the YB equation "at roots of unity" are related to algebraic
curves of genus *g* > 1; They are also known to be connected
with the "chiral Potts model".

@ __General references__:
Korepanov in(86)nl/00;
Jimbo IJMPA(89) [intro];
Babelon & Viallet pr(89);
Perk & Au-Yang en(06)mp [rev];
Nichita a1506 [computational methods and applications].

@ __Generalizations__: Ambjørn et al NPB(06) [3D, Zamolodchikov's tetrahedron equations, simplified].

> __Online resources__:
see John Baez page;
Wikipedia page.

**Yang-Lee Theory**
> see under Lee-Yang Theorem / Theory.

**Yang-Mills Algebra**

@ __References__: Herscovich & Solotar AM(11) [representations].

**Yano Tensor**

@ __References__: Cariglia CQG(04)ht/03 [and the Dirac equation in curved spacetime].

**Yarkovsky Effect**
> s.a. Asteroids.

* __Idea__: A non-gravitational
force acting on celestial bodies, e.g., asteroids, from recoil due to
re-emission of heat absorbed from the Sun.

@ __References__:
Lorenz & Spitale Icarus(04) [as heat engine];
news BBC(07)mar,
pw(07)mar [observation];
De Vos & Kaplar AJP(10)jun [influence on the energy balance and surface temperature];
Vokrouhlický et al a1502-ch [and its rotational variant, the YORP effect].

**Yilmaz Theory**

* __Idea__: An alternative, 4D,
curved spacetime theory of gravity, in which the Ricci curvature is defined in
terms of a massless Klein-Gordon scalar field on an initially flat spacetime, and
satisfies the Einstein equation with the usual scalar field stress-energy tensor;
It predicts the existence of *N*-body interacting solutions without event
horizons.

@ __General references__: Yilmaz PR(58),
comment Hoffmann JMM(60);
Misner NCB(99)gq/95;
Alley & Yilmaz NCB(99)gq/95;
Wyss NCB(99);
Alley et al ap/99/ApJL;
Ibison CQG(06)-a0705 [FLRW models].

@ __Exponential metric__: Martinis & Perković a1009/FP [and Newtonian gravity].

**York Time**
> see time in gravity.

**Young Diagrams / Tableaux**
> s.a. group representations.

* __Idea__: A diagrammatic way
of describing representations of finite and compact Lie groups.

* __Examples__: For SU(*n*),
denoting the fundamental representation by a box \(\square\) and the conjugate
one by a column of *n*−1 boxes, we get:

* __Dimension__: The dimension
of such a representation can be calculated as follows: ...

@ __References__: Hamermesh 63;
Fulton 96 [applications to representation theory and geometry];
Mironov & Morozov a1912 [hook variables, cut-and-join operators and τ-functions].

> __Online resources__:
see Wikipedia page.

**Young's Double Slit Experiment**
> see experiments in physics; interference.

**Yukawa Potential**
> s.a. renormalization [Yukawa theories with fermions].

* __Idea__: An exponential potential
*U*(*r*) = exp(−*r*/*λ*)/*r*,
introduced by Yukawa to describe a meson-mediated interaction, where the length
scale *λ* is related to the mass of the particle.

@ __References__: Gönül et al PS(06) [quantum, eigenvalues and eigenfunctions];
Haque & Joglekar a1004 [1+1, causality];
Toms PRD(18)-a1805 [in curved spacetime];
> s.a. chaotic systems.

> __And gravity__:
see modified newtonian gravity
and tests.

> __Online resources__:
see Wikipedia page.

main page
– abbreviations
– journals – comments
– other sites – acknowledgements

send feedback and suggestions to bombelli at olemiss.edu – modified 29 feb 2020