Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: PQCD Analysis of Inclusive Semileptonic Decays of A Polarized Lambda_b
  Baryon   We investigate the Lambda_b polarization problem in the inclusive
semileptonic decays of a polarized Lambda_b baryon, using the modified
perturbative QCD formalism which includes Sudakov suppression. According to
HQEFT, we show that, at the leading order in the 1/M_b expansion, the polarized
and unpolarized distribution functions become one single universal distribution
function. To explore the mechanisms which determine the spin properties of a
polarized Lambda_b baryon, we construct four formalisms which are the naive
quark model (QM), the modified quark model (MQM), the naive parton model (PM)
and the modified parton model (MPM), and calculate their corresponding Lambda_b
polarizations, denoted as P's. The modified quark and parton models are with
Sudakov suppression. The resulting P's are -0.23 (QM), -0.94 (MQM), -0.37 (PM)
and -0.68 (MPM), respectively. We note that P_MQM (equal to -0.94) is very
close the b quark polarization asymmetry, A_RL=-0.94, calculated at the Z
vertex in Z -> b bar{b} process, and that P_MPM (equal to -0.68) is also very
close to the Lambda_b polarization (equal to -0.68) which was estimated from
the fragmentation processes under the heavy quark limit. Based on our analysis,
there exists no any paradox in the theoretical explanations of the Lambda_b
polarization for the experimental data.

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The categories of this paper are: atom-ph
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: stat
7
The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci