Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for the b --> d gamma process   We report search results for the flavor-changing neutral current process b
--> d gamma with a data sample containing 274 million B meson pairs accumulated
at the Upsilon(4S) resonance with the Belle detector at KEKB. We studied the
exclusive decays B- --> rho- gamma, B0bar --> rho0 gamma, and B0bar --> omega
gamma, and find no significant signal. We set an upper limit for a combined
branching fraction Br(B --> (rho,omega) gamma) < 1.4 x 10-6 at the 90%
confidence level, which is normalized to that of B- --> rho- gamma assuming an
isospin relation between the three modes.

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The categories of this paper are: nlin
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The categories of this paper are: supr-con
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas