Physlib.QFT.PerturbationTheory.FieldStatistics.Basic
42 declarations
Quantum field statistics (bosonic vs. fermionic)
#FieldStatisticThe type is an inductive type consisting of exactly two elements: and . It is used to categorize whether a physical field or operator obeys Bose-Einstein statistics (bosonic) or Fermi-Dirac statistics (fermionic).
Decidability of for field statistics
#instDecidableEqFieldStatisticFor any two field statistics , it is decidable whether . This means there exists an algorithmic procedure to determine if two given statistics are both , both , or different.
Commutative group structure on field statistics ()
#instCommGroupThe type forms a commutative group where the identity element is . The group operation follows the rules of parity: - - - - In this structure, every element is its own inverse, and the group is isomorphic to .
In the commutative group of quantum field statistics (), where is the identity element, the product of a bosonic statistic with itself is a bosonic statistic. That is:
In the commutative group of quantum field statistics (), where the identity element is and the non-trivial element is , the product of a bosonic statistic and a fermionic statistic is a fermionic statistic. That is:
In the commutative group of quantum field statistics (), where the identity element is and the non-trivial element is , the product of a fermionic statistic and a bosonic statistic is a fermionic statistic. That is:
In the commutative group of field statistics (), the product of two fermionic statistics is a bosonic statistic. This reflects the parity structure where the combination of two odd (fermionic) elements results in an even (bosonic) element:
In the commutative group of quantum field statistics , which classifies fields as either or , the product of any statistic with the statistic is equal to : This confirms that the statistic acts as the identity element within this group structure.
for any field statistic
#mul_selfFor any field statistic , the product of with itself is the identity element of the commutative group of field statistics, i.e., . This identity element corresponds to the bosonic statistic.
is a finite type
#instFintypeThe type , which classifies quantum fields as either or , is a finite type (an instance of `Fintype`). It consists of exactly two distinct elements: .
The field statistics and are not equal, i.e., .
The equality between the field statistics and is equivalent to .
For any quantum field statistic , is not fermionic if and only if is bosonic. Here, is the type classifying fields as either or .
For any field statistic , it holds that if and only if .
For any field statistic , the condition that is not bosonic is equivalent to the condition that is fermionic. In mathematical notation, .
For any field statistic , it holds that is not equal to if and only if is equal to . In mathematical terms, for , .
for field statistics
#mul_eq_one_iffFor any quantum field statistics , the product is equal to the identity element (the statistic) if and only if . The type classifies fields as either or and forms a commutative group where every element is its own inverse.
for field statistics
#one_eq_mul_iffIn the commutative group of quantum field statistics (where elements are either or ), the product of two statistics and is the identity element (the statistic) if and only if and are equal.
for field statistics
#mul_eq_iff_eq_mulFor any quantum field statistics , the product if and only if . Here, is the type classifying fields as either or , forming a commutative group where the identity element is and every element is its own inverse ().
for field statistics
#mul_eq_iff_eq_mul'For any quantum field statistics , the product holds if and only if . Here, is the type classifying fields as either bosonic or fermionic, forming a commutative group where the identity element is bosonic and every element is its own inverse (i.e., for any statistic ).
Field statistic of a list of fields
#ofListGiven a mapping that assigns a statistic (either or ) to each field in a collection , the function determines the collective statistic of a finite list of fields . The resulting statistic is if there is an odd number of fields in the list for which ; otherwise, the result is . Mathematically, this corresponds to the product where the statistics follow the group rules of .
Let be a mapping that assigns a statistic (either or ) to each field in a collection . For any field and any finite list of fields , the collective statistic of the list formed by prepending to (denoted ) is equal to the product of the statistic of and the collective statistic of the original list : where the multiplication follows the group structure of (where is the identity and ).
Let be a collection of fields and be a mapping that assigns a statistic (bosonic or fermionic) to each field. For any list of fields , the collective statistic is equal to the product of the statistics of the individual fields in the list: where the product is taken in the commutative group structure of (with as the identity).
The statistic of a singleton list equals
#ofList_singletonGiven a collection of fields and a mapping that assigns a statistic (bosonic or fermionic) to each field, the collective statistic of a singleton list containing exactly one field is equal to the statistic of that field, .
Let be a collection of fields and be a mapping that assigns a statistic (either or ) to each field. For any field , the collective field statistic of the field when represented as a single-element word in the free monoid, denoted by , is equal to the statistic of the individual field .
The collective statistic of an empty list is
#ofList_emptyGiven a mapping that assigns a statistic (either or ) to each field in a collection , the collective field statistic of an empty list of fields is .
The collective statistic of concatenated lists is bosonic if and only if the individual lists have equal statistics
#ofList_appendGiven a mapping that assigns a statistic (either or ) to each field, the collective statistic of the concatenation of two lists of fields and is if the collective statistics of the individual lists and are equal, and otherwise.
Let be a mapping that assigns a statistic (either or ) to each field in a collection . For any two finite lists of fields and , the collective field statistic of their concatenation is equal to the product of the collective statistics of the individual lists: where the multiplication follows the rules of the commutative group (isomorphic to ), where is the identity element.
The Collective Field Statistic is Invariant Under Permutation of Fields
#ofList_permLet be a mapping that assigns a field statistic (either or ) to each field in a collection . For any two lists of fields and , if is a permutation of , then their collective field statistics are equal: This property arises because the collective statistic is calculated as the product of individual statistics within a commutative group.
Let be a mapping that assigns a statistic (either or ) to each field in a collection . For any list of fields , field , and decidable ordering relation on , the collective field statistic of the list obtained by performing an ordered insertion of into is equal to the collective statistic of the list formed by prepending to the front of :
Insertion Sort Preserves the Collective Field Statistic
#ofList_insertionSortLet be a mapping that assigns a statistic (either or ) to each field in a collection . For any list of fields and any decidable binary relation on , the collective field statistic of the list sorted via the insertion sort algorithm is equal to the collective field statistic of the original list: This result follows from the fact that insertion sort is a permutation of the original list, and the collective statistic (defined as the product of individual statistics in a commutative group) is invariant under permutations.
Collective statistic of sub-selected fields as a finite product over indices
#ofList_map_eq_finset_prodLet be a mapping that assigns a statistic to each field. For any list of fields and any list of indices into such that contains no duplicate indices, the collective statistic of the list of fields selected by is equal to the product over all indices of if , and the bosonic statistic (the identity ) otherwise. Mathematically: where the map operation constructs a new list of fields by selecting elements from at the indices specified in .
Let be a mapping that assigns a statistic (either or ) to each field in a collection . For any two fields , the collective field statistic of the list containing these two fields is equal to the product of their individual statistics: where the multiplication follows the commutative group structure of (with as the identity element).
The collective statistic is invariant under field insertion at index
#ofList_take_insertGiven a mapping that assigns a statistic (either or ) to each field, let be a list of fields and be a natural number. The collective field statistic of the first elements of is equal to the collective field statistic of the first elements of the list obtained by inserting a field into at index . Mathematically, this is expressed as: where denotes the sublist of the first elements and denotes the insertion of an element at a specific position.
The field statistic of the first elements is invariant under erasing the -th element
#ofList_take_eraseIdxLet be a collection of fields and be a mapping that assigns a statistic (either or ) to each field. For any list of fields and any natural number , the collective field statistic of the first elements of the list remains unchanged if the element at index is removed from . That is, where returns the first elements of a list , and removes the element at the -th position.
The collective statistic of the first fields is (bosonic)
#ofList_take_zeroFor any list of fields and any mapping that assigns a statistic to each field, the collective field statistic of the first elements of is the identity element (which represents the bosonic statistic). Mathematically, this is expressed as: where denotes the sublist containing the first zero elements (the empty list).
Let be a mapping that assigns a statistic (either bosonic or fermionic) to each field in a collection . For any natural number , field , and list of fields , the collective field statistic of the first elements of the list formed by prepending to is equal to the product of the statistic of and the collective field statistic of the first elements of . Mathematically: where denotes the sublist of the first elements of , and the multiplication follows the group structure of field statistics.
The field statistic of the first elements is invariant under insertion at index
#ofList_take_insertIdx_gtLet be a mapping that assigns a statistic (either bosonic or fermionic) to each field in a collection . For any list of fields , any field , and any natural numbers and such that , the collective field statistic of the first elements of the list obtained by inserting into at index is equal to the collective field statistic of the first elements of the original list .
The collective statistic of a sublist is invariant under the insertion position of a field within that sublist
#ofList_insert_lt_eqLet be a mapping that assigns a statistic (either or ) to each field in a collection . For any list of fields , a field , and natural numbers and such that and is within the bounds of the list (), the collective field statistic of the first elements of the list obtained by inserting into at index is equal to the collective field statistic of the first elements of the list obtained by prepending to the front of . Mathematically: where denotes the insertion of element into list at position , and denotes the sublist consisting of the first elements of .
Let be a mapping that assigns a statistic (either or ) to each field in a collection . For any list of fields , a field , and natural numbers and such that and is within the bounds of the list (), the collective field statistic of the first elements of the list obtained by inserting into at index is equal to the product of the statistic of and the collective field statistic of the first elements of the original list . Mathematically: where denotes the insertion of element into list at position , denotes the sublist consisting of the first elements of , and the multiplication follows the group structure of field statistics.
Additive monoid structure on ()
#instAddMonoidThe type is endowed with an additive monoid structure. In this structure, the additive identity element (zero) is . The addition of two statistics is defined to be equal to their multiplication in the underlying commutative group. Specifically, the addition follows parity rules: - - - For any natural number and statistic , the natural scalar multiplication is defined as the -fold sum of , which corresponds to the product .
for field statistics
#add_eq_mulFor any two field statistics (which can be either bosonic or fermionic), the sum in the additive monoid is equal to the product in the commutative group.
