Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comments on the Hydrogen Atom Spectrum in the Noncommutative Space   There has been disagreement in the literature on whether the hydrogen atom
spectrum receives any tree-level correction due to noncommutativity. Here we
shall clarify the issue and show that indeed a general argument on the
structure of proton as a nonelementary particle leads to the appearance of such
corrections. As a showcase, we evaluate the corrections in a simple
nonrelativistic quark model with a result in agreement with the previous one we
had obtained by considering the electron moving in the external electric field
of proton. Thus the previously obtained bound on the noncommutativity
parameter, $\theta < (10^4 GeV)^{-2}$, using the Lamb shift data, remains
valid.

24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
9
The categories of this paper are: nlin