1,099 research outputs found
Migdal Effect in Dark Matter Direct Detection Experiments
The elastic scattering of an atomic nucleus plays a central role in dark
matter direct detection experiments. In those experiments, it is usually
assumed that the atomic electrons around the nucleus of the target material
immediately follow the motion of the recoil nucleus. In reality, however, it
takes some time for the electrons to catch up, which results in ionization and
excitation of the atoms. In previous studies, those effects are taken into
account by using the so-called Migdal's approach, in which the final state
ionization/excitation are treated separately from the nuclear recoil. In this
paper, we reformulate the Migdal's approach so that the "atomic recoil" cross
section is obtained coherently, where we make transparent the energy-momentum
conservation and the probability conservation. We show that the final state
ionization/excitation can enhance the detectability of rather light dark matter
in the GeV mass range via the {\it nuclear} scattering. We also discuss the
coherent neutrino-nucleus scattering, where the same effects are expected.Comment: Integrated probability data fixed and Si.dat adde
Bulk properties of nuclear matter in the relativistic Hartree approximation with cut-off regularization
A method of cut-off regularization is proposed to evaluate vacuum corrections
in nuclear matter in the framework of the Hartree approximation. Bulk
properties of nuclear matter calculated by this method are a good agreement
with results analyzed by empirical values. The vacuum effect is quantitatively
evaluated through a cut-off parameter and its role for saturation property and
compressional properties is clarified.Comment: PACS numbers, 21.65.+f, 21.30.+
Decay of I-ball/Oscillon in Classical Field Theory
I-balls/oscillons are long-lived and spatially localized solutions of real
scalar fields. They are produced in various contexts of the early universe in,
such as, the inflaton evolution and the axion evolution. However, their decay
process has long been unclear. In this paper, we derive an analytic formula of
the decay rate of the I-balls/oscillons within the classical field theory. In
our approach, we calculate the Poynting vector of the perturbation around the
I-ball/oscillon profile by solving a relativistic field equation, with which
the decay rate of the I-ball/oscillon is obtained. We also perform a classical
lattice simulation and confirm the validity of our analytical formula of the
decay rate numerically.Comment: citations adde
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