Exploring dark sector parameters in light of neutron star temperatures. (arXiv:2102.11151v2 [hep-ph] UPDATED)
<a href="http://arxiv.org/find/hep-ph/1/au:+Lin_G/0/1/0/all/0/1">Guey-Lin Lin</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Lin_Y/0/1/0/all/0/1">Yen-Hsun Lin</a>
Using neutron stars (NS) as a dark matter (DM) probe has gained broad
attention recently, either from heating due to DM annihilation or its stability
under the presence of DM. In this work, we investigate spin-$1/2$ fermionic DM
$chi$ charged under the $U(1)_{X}$ in the dark sector. The massive gauge boson
$V$ of $U(1)_{X}$ gauge group can be produced in NS via DM annihilation. The
produced gauge boson can decay into Standard Model (SM) particles before it
exits the NS, despite its tiny couplings to SM particles. Thus, we perform a
systematic study on $chibar{chi}to2Vto4{rm SM}$ as a new heating
mechanism for NS in addition to $chibar{chi}to2{rm SM}$ and kinetic
heating from DM-baryon scattering. The self-trapping due to $chi V$ scattering
is also considered. We assume the general framework that both kinetic and mass
mixing terms between $V$ and SM gauge bosons are present. This allows both
vector and axial-vector couplings between $V$ and SM fermions even for $m_Vll
m_Z$. Notably, the contribution from axial-vector coupling is not negligible
when particles scatter relativistically. We point out that the above approaches
to DM-induced NS heating are not yet adopted in recent analyses.
Detectabilities of the aforementioned effects to the NS surface temperature by
the future telescopes are discussed as well.
Using neutron stars (NS) as a dark matter (DM) probe has gained broad
attention recently, either from heating due to DM annihilation or its stability
under the presence of DM. In this work, we investigate spin-$1/2$ fermionic DM
$chi$ charged under the $U(1)_{X}$ in the dark sector. The massive gauge boson
$V$ of $U(1)_{X}$ gauge group can be produced in NS via DM annihilation. The
produced gauge boson can decay into Standard Model (SM) particles before it
exits the NS, despite its tiny couplings to SM particles. Thus, we perform a
systematic study on $chibar{chi}to2Vto4{rm SM}$ as a new heating
mechanism for NS in addition to $chibar{chi}to2{rm SM}$ and kinetic
heating from DM-baryon scattering. The self-trapping due to $chi V$ scattering
is also considered. We assume the general framework that both kinetic and mass
mixing terms between $V$ and SM gauge bosons are present. This allows both
vector and axial-vector couplings between $V$ and SM fermions even for $m_Vll
m_Z$. Notably, the contribution from axial-vector coupling is not negligible
when particles scatter relativistically. We point out that the above approaches
to DM-induced NS heating are not yet adopted in recent analyses.
Detectabilities of the aforementioned effects to the NS surface temperature by
the future telescopes are discussed as well.
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