Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nucleon decay in gauge unified models with intersecting D6-branes   Baryon number violation is discussed in gauge unified orbifold models of type
II string theory with intersecting Dirichlet branes. We consider setups of
D6-branes which extend along the flat Minkowski space-time directions and wrap
around 3-cycles of the internal 6-d manifold. The discussion is motivated by
the enhancement effect of low energy amplitudes anticipated for M-theory and
type II string theory models with matter modes localized at points of the
internal manifold. The conformal field theory formalism is used to evaluate the
open string amplitudes at tree level. We study the single baryon number
violating processes of dimension 6 and 5, involving four quarks and leptons and
in supersymmetry models, two pairs of matter fermions and superpartner
sfermions. The higher order processes associated with the baryon number
violating operators of dimension 7 and 9 are also examined, but in a
qualitative way. We discuss the low energy representation of string theory
amplitudes in terms of infinite series of poles associated to exchange of
string Regge resonance and compactification modes. The comparison of string
amplitudes with the equivalent field theory amplitudes is first studied in the
large compactification radius limit. Proceeding next to the finite
compactification radius case, we present a numerical study of the ratio of
string to field theory amplitudes based on semi-realistic gauge unified
non-supersymmetric and supersymmetric models employing the Z3 and Z2xZ2
orbifolds. We find a moderate enhancement of string amplitudes which becomes
manifest in the regime where the gauge symmetry breaking mass parameter exceeds
the compactification mass parameter, corresponding to a gauge unification in a
seven dimensional space-time.

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The categories of this paper are: math-ph
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics