Hot new early dark energy: Dark radiation matter decoupling

We present a microscopic model of the dark sector that resolves the Hubble tension within standard current datasets (Planck 2018, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mi>Pantheon</a:mi> <a:mo>+</a:mo> </a:mrow> </a:math> and DESI DR2 BAO) based on well-known fundamental principles, gauge symmetry and spontaneous symmetry breaking. It builds on the hot new early dark energy (Hot NEDE) setup, featuring a dark <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>S</c:mi> <c:mi>U</c:mi> <c:mo stretchy="false">(</c:mo> <c:mi>N</c:mi> <c:mo stretchy="false">)</c:mo> </c:math> gauge symmetry broken to <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>S</g:mi> <g:mi>U</g:mi> <g:mo stretchy="false">(</g:mo> <g:mi>N</g:mi> <g:mo>−</g:mo> <g:mn>1</g:mn> <g:mo stretchy="false">)</g:mo> </g:math> in a supercooled phase transition that creates a thermal bath of self-interacting dark radiation in the epoch between big bang nucleosynthesis and recombination. Adding a fermion multiplet charged under the gauge symmetry provides a naturally stable component of dark matter that interacts with dark radiation. Spontaneous symmetry breaking predicts a decoupling of this interaction once the dark sector cools down, that we refer to as dark radiation matter decoupling (DRMD). We also provide a simplified DRMD model that captures the essential features of the full theory while retaining additional falsifiable predictions. Using the datasets stated above, we find agreement with the <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:mrow> <k:msub> <k:mrow> <k:mi>SH</k:mi> </k:mrow> <k:mrow> <k:mn>0</k:mn> </k:mrow> </k:msub> <k:mi>ES</k:mi> </k:mrow> </k:math> determination of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:msub> <m:mi>H</m:mi> <m:mn>0</m:mn> </m:msub> </m:math> at the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mrow> <o:mn>1.4</o:mn> <o:mi>σ</o:mi> </o:mrow> </o:math> level, compared to a <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:mrow> <q:mn>5.7</q:mn> <q:mi>σ</q:mi> </q:mrow> </q:math> tension in <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:mi mathvariant="normal">Λ</s:mi> <s:mi>CDM</s:mi> </s:math> , thereby providing a resolution of the Hubble tension.