Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interaction of Ultracold Antihydrogen with a Conducting Wall   We investigate the interaction of ultracold antihydrogen with a conducting
surface. Our discussion focuses on the physical regime where the phenomenon of
quantum reflection manifests. We calculate the reflection probability as
function of incident atom energy. We find that, for ground state $\bar{H}$
atoms (with $T< 10^{-5}$ K), the probability of reflection is $R \simeq 1-k b$,
where $k$ is the momentum of the atom and $b = 2174.0$ a.u. is a constant
determined solely by the van der Waals-Casimir tail of the atom-wall
interaction. We show that quantum reflection, which suppresses the direct
contact of ultra-cold atoms with the surface, allows for the possibility of
confinement and storage of cold antihydrogen atoms. We calculate the life-time
of confinement as a function of antihydrogen energy. We develop a theory of
$\bar{H}$ in a wave-guide and propose its application to fundamental
measurements. In particular, for measurement of retardation corrections in the
long-range component of the antiatom - wall potential. We demonstrate, for
$\bar{H}$ falling in the gravitational field of Earth onto a conducting
surface, the existence of quantized $\bar{H}$ states. We calculate that the
lifetime of ultracold $\bar{H}$ in its lowest gravitational state and obtain
$\tau=(Mg b/2\hbar)^{-1}\simeq 0.1$ s, where $Mg$ is a gravitational force
acting on the antiatom. We propose that measurement of this lifetime may
provide a new test for the gravitational properties of antimatter.

4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin