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Problem

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problem description

# Problem setup: Consider fermion fields that are adjoint representations of a U(N)U(N) gauge group. Suppose fields carry a U(1)U(1) R-charge whose fugacity is qq. A generating function of the Witten index, for example, could be IN(q)=1−q+q2+...I_N(q)=1-q+q^2+..., which means the index at charge 1 is -1 and the index at charge 2 is 1. # Main problem: Compute the generating function of the index of trace relations up to charge 15 in a free U(2)U(2) gauge theory that contains only two adjoint fields: a charge 1 fermion ψ\psi, and its derivative field ∂ψ\partial\psi with charge 2.
Plain-text mathematical notation (without MathML)
# Problem setup:
Consider fermion fields that are adjoint representations of a U(N) gauge group. Suppose fields carry a U(1) R-charge whose fugacity is q. A generating function of the Witten index, for example, could be I_(N)(q)=1−q+q²+..., which means the index at charge 1 is -1 and the index at charge 2 is 1.

# Main problem:
Compute the generating function of the index of trace relations up to charge 15 in a free U(2) gauge theory that contains only two adjoint fields: a charge 1 fermion ψ, and its derivative field ∂ψ with charge 2.
Original LaTeX notation
# Problem setup:
Consider fermion fields that are adjoint representations of a $U(N)$ gauge group. Suppose fields carry a $U(1)$ R-charge whose fugacity is $q$. A generating function of the Witten index, for example, could be $I_N(q)=1-q+q^2+...$, which means the index at charge 1 is -1 and the index at charge 2 is 1.

# Main problem:
Compute the generating function of the index of trace relations up to charge 15 in a free $U(2)$ gauge theory that contains only two adjoint fields: a charge 1 fermion $\psi$, and its derivative field $\partial\psi$ with charge 2.

code template

Code

import sympy as sp

q = sp.symbols('q')

def answer(q):
    r"""
    Return the expression of the generating function in SymPy format.

    Inputs
    ----------
    q: sympy.Symbol, Fugacity for the U(1) R-charge, $q$

    Outputs
    ----------
    generating_func: sympy.Expr, the generating function of the index of trace relations to up charge 15 in a free $U(2)$ gauge theory
    """

    # ------------------ FILL IN YOUR RESULTS BELOW ------------------
    generating_func = ...   # a SymPy expression of inputs
    # ---------------------------------------------------------------

    return generating_func

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Source and history

Official source

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