Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rare $\Lambda_{b}\to \Lambda $ l$^{+}$ l$^{-}$ Decays with Polarized
  $\Lambda $   We investigate the rare baryonic exclusive decays of $\Lambda_b\to \Lambda
l^+ l^- (l=e,\mu,\tau)$ with polarized $\Lambda $. Under the approximation of
the heavy quark effective theory (HQET), in the standard model we derive the
differential decay rates and various polarization asymmetries by including
lepton mass effects. We find that with the long-distance effects the decay
branching ratios are $5.3\times 10^{-5}$ for $\Lambda_b\to \Lambda l^+ l^-\
(l=e,\mu)$ and $1.1\times 10^{-5}$ for $\Lambda_b\to \Lambda \tau^+\tau^-$. The
effects of new physics in the decay rates are also discussed. The integrated
longitudinal $\Lambda$ polarizations are -0.31 and -0.12, while that of the
normal ones 0.02 and 0.01, for di-muon and tau modes, respectively. The CP-odd
transverse polarization of $\Lambda$ is zero in the standard model but it is
expected to be sizable in some theories with new physics.

33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ