If is a polynomial in several variables, then there is a non-zero polynomial and a differential operator with polynomial coefficients such that The Bernstein–Sato polynomial is the monic polynomial of smallest degree amongst such polynomials. Its existence can be shown using the notion of holonomic D-modules. proved that all roots of the Bernstein–Sato polynomial are negative rational numbers. The Bernstein–Sato polynomial can also be defined for products of powers of several polynomials. In this case it is a product of linear factors with rational coefficients. generalized the Bernstein–Sato polynomial to arbitrary varieties. Note, that the Bernstein–Sato polynomial can be computed algorithmically. However, such computations are hard in general. There are implementations of related algorithms in computer algebra systems RISA/Asir, Macaulay2, and SINGULAR. presented algorithms to compute the Bernstein–Sato polynomial of an affine variety together with an implementation in the computer algebra system SINGULAR. described some of the algorithms for computing Bernstein–Sato polynomials by computer.
Examples
If then
If then
The Bernstein–Sato polynomial of x2 + y3 is
If tij are n2 variables, then the Bernstein–Sato polynomial of det is given by
If f is a polynomial, not identically zero, then it has an inverse g that is a distribution; in other words, f g = 1 as distributions. If f is non-negative the inverse can be constructed using the Bernstein–Sato polynomial by taking the constant term of the Laurent expansion of fs at s = −1. For arbitrary f just take times the inverse of
showed how to use the Bernstein polynomial to define dimensional regularization rigorously, in the massive Euclidean case.
The Bernstein-Sato functional equation is used in computations of some of the more complex kinds of singular integrals occurring in quantum field theory. Such computations are needed for precision measurements in elementary particle physics as practiced for instance at CERN. However, the most interesting cases require a simple generalization of the Bernstein-Sato functional equation to the product of two polynomials, with x having 2-6 scalar components, and the pair of polynomials having orders 2 and 3. Unfortunately, a brute force determination of the corresponding differential operators and for such cases has so far proved prohibitively cumbersome. Devising ways to bypass the combinatorial explosion of the brute force algorithm would be of great value in such applications.
