Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of vortex particles via weak measurements   While twisted photons with orbital angular momentum can be generated in many
ways, their massive counterparts -- vortex electrons, neutrons, or atoms -- can
be obtained so far only via diffraction techniques, not applicable for
relativistic energies. Here we show that vortex particles of arbitrary mass,
spin, and energy, including hadrons, ions, and nuclei, can be generated during
emission in helical undulators, via Cherenkov radiation, in collisions with
intense laser beams, in such scattering and annihilation processes as $e\mu \to
e\mu, ep \to ep$, etc. We elucidate that the key element in obtaining them is
largely not the process itself but the post-selection protocol due to quantum
entanglement. A final particle acquires a phase vortex if the other final
particle's momentum is weakly measured with no post-selection of its azimuthal
angle. This technique can be adapted for ultrarelativistic beams of modern and
future colliders for hadronic and spin studies, and it can also facilitate the
development of sources of hard X-ray and $\gamma$-range twisted photons at
storage rings and free-electron lasers.

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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat