Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron electric dipole moment using lattice QCD simulations at the
  physical point   We extract the neutron electric dipole moment $\vert \vec{d}_N\vert$ within
the lattice QCD formalism. We analyse one ensemble of $N_f=2+1+1$ twisted mass
clover-improved fermions with lattice spacing of $a \simeq 0.08 \ {\rm fm}$ and
physical values of the quark masses corresponding to a pion mass $m_{\pi}
\simeq 139 \ {\rm MeV}$. The neutron electric dipole moment is extracted by
computing the $CP$-odd electromagnetic form factor $F_3(Q^2 \to 0)$ through
small $\theta$-expansion of the action. This approach requires the calculation
of the topological charge for which we employ a fermionic definition by means
of spectral projectors while we also provide a comparison with the gluonic
definition accompanied by the gradient flow. We show that using the topological
charge from spectral projectors leads to absolute errors that are more than two
times smaller than those provided when the field theoretic definition is
employed. We find a value of $\vert \vec{d}_N\vert = 0.0009(24) \ \theta \ e
\cdot {\rm fm}$ when using the fermionic definition, which is statistically
consistent with zero.

21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom