Physlib

Physlib.Relativity.Fermions.Weyl.RightHanded

Right handed Weyl fermions

In this file we define Right handed Weyl fermions. These sit in the conjugate representation of `SL(2,ℂ)`, and we consider them to have up indices `ψ^{\dot α}` with `α = 1,2`.

Underlying module structure

Basis

Representation

12 declarations

definition

Right-handed Weyl fermions C2\simeq \mathbb{C}^2

The canonical equivalence between the type of right-handed Weyl fermions and the complex vector space C2\mathbb{C}^2 (represented as the space of functions from a set of two elements to C\mathbb{C}).

instance

Additive commutative monoid of right-handed Weyl fermions

The space of right-handed Weyl fermions, represented by the type `Fermion.RightHandedWeyl` (which wraps C2\mathbb{C}^2), is equipped with the structure of an additive commutative monoid. This defines a commutative and associative addition operation and a zero element 00 for right-handed Weyl spinors.

instance

Right-handed Weyl fermions form an additive commutative group

The space of right-handed Weyl fermions, represented by the type `Fermion.RightHandedWeyl` (which is isomorphic to the complex vector space C2\mathbb{C}^2), is equipped with an additive commutative group structure.

instance

Complex module structure of right-handed Weyl fermions

The type of right-handed Weyl fermions, `Fermion.RightHandedWeyl`, carries the structure of a module over the field of complex numbers C\mathbb{C}. This defines `Fermion.RightHandedWeyl` as a complex vector space.

definition

C\mathbb{C}-linear isomorphism between right-handed Weyl fermions and C2\mathbb{C}^2

A C\mathbb{C}-linear isomorphism between the space of right-handed Weyl fermions and the standard complex vector space C2\mathbb{C}^2 (modeled as functions from a set of two elements to C\mathbb{C}).

abbrev

Conversion of right-handed Weyl fermions to C2\mathbb{C}^2

The function maps a right-handed Weyl fermion to its representation as a vector in C2\mathbb{C}^2.

theorem

ψ.toFin2C=ψ.val\psi.\text{toFin2}\mathbb{C} = \psi.\text{val} for Right-Handed Weyl Fermions

For any right-handed Weyl fermion ψ\psi, the mapping of ψ\psi to its representation in the complex vector space C2\mathbb{C}^2 (denoted by ψ.toFin2C\psi.\text{toFin2}\mathbb{C}) is equal to its underlying value ψ.val\psi.\text{val}.

definition

Basis for right-handed Weyl fermions

A basis for the space of right-handed Weyl fermions Fermion.RightHandedWeyl\text{Fermion.RightHandedWeyl}, which is a 2-dimensional vector space over the complex numbers C\mathbb{C}. The basis is indexed by the set {0,1}\{0, 1\}.

theorem

Components of the right-handed Weyl fermion basis are δij\delta_{ij}

For any indices i,j{0,1}i, j \in \{0, 1\}, the jj-th component of the ii-th basis vector of the space of right-handed Weyl fermions is equal to 11 if i=ji = j and 00 otherwise. In terms of the Kronecker delta, this is expressed as (ei)j=δij(e_i)_j = \delta_{ij}.

theorem

The basis of right-handed Weyl fermions is the standard basis eie_i

For each index i{0,1}i \in \{0, 1\}, the ii-th basis vector of the vector space of right-handed Weyl fermions is the standard basis vector eie_i (where the jj-th component is given by the Kronecker delta δij\delta_{ij}).

definition

Right-handed Weyl representation of SL(2,C)SL(2, \mathbb{C})

The complex representation of the special linear group SL(2,C)SL(2, \mathbb{C})—the group of 2×22 \times 2 complex matrices with determinant 1—acting on the vector space of right-handed Weyl spinors.

theorem

Representation of SL(2,C)SL(2, \mathbb{C}) on right-handed Weyl fermions involves complex conjugation

Let MSL(2,C)M \in SL(2, \mathbb{C}) be a 2×22 \times 2 complex matrix with determinant 1, and let ψ\psi be a right-handed Weyl fermion (represented as a 2-component complex vector). The action of the representation of MM on ψ\psi is given by the matrix-vector product of the complex conjugate of MM and ψ\psi: (rep M)ψ=Mˉψ (\text{rep } M) \psi = \bar{M} \psi where Mˉ\bar{M} denotes the element-wise complex conjugate of the matrix MM.