We investigate the consequences of a nonzero bulk viscosity coefficient on the transverse momentum spectra, azimuthal momentum anisotropy, and multiplicity of charged hadrons produced in heavy ion collisions at LHC energies. The agreement between a r
ealistic 3D hybrid simulation and the experimentally measured data considerably improves with the addition of a bulk viscosity coefficient for strongly interacting matter. This paves the way for an eventual quantitative determination of several QCD transport coefficients from the experimental heavy ion and hadron-nucleus collision programs.
We report measurements of branching fractions of $tau$ lepton decays to final states with a $K^{0}_{S}$ meson using a 669 fb$^{-1}$ data sample accumulated with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The inclusive bra
nching fraction is measured to be $mathcal{B}(tau^{-} to K^{0}_{S} X^{-} u_{tau})=(9.15 pm 0.01 pm 0.15) times 10^{-3}$, where $X^{-}$ can be anything; the exclusive branching fractions are $mathcal{B}(tau^{-} to pi^{-} K^{0}_{S} u_{tau}) = (4.16 pm 0.01 pm 0.08) times 10^{-3}$, $mathcal{B}(tau^{-} to K^{-} K^{0}_{S} u_{tau}) = (7.40 pm 0.07 pm 0.27) times 10^{-4}$, $mathcal{B}(tau^{-} to pi^{-} K^{0}_{S} pi^{0} u_{tau}) = (1.93 pm 0.02 pm 0.07) times 10^{-3}$, $mathcal{B}(tau^{-} to K^{-} K^{0}_{S} pi^{0} u_{tau}) = (7.48 pm 0.10 pm 0.37)times 10^{-4}$, $mathcal{B}(tau^{-} to pi^{-} K^{0}_{S} K^{0}_{S} u_{tau}) = (2.33 pm 0.03 pm 0.09) times 10^{-4}$, $mathcal{B}(tau^{-} to pi^{-} K^{0}_{S} K^{0}_{S} pi^{0} u_{tau}) = (2.00 pm 0.22 pm 0.20) times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. For each mode, the accuracy is improved over that of pre-$B$-factory measurements by a factor ranging from five to ten. In $tau^{-} to pi^{-} K^0_S K^0_S pi^{0} u_{tau}$ decays, clear signals for the intermediate states $tau^{-} to pi^- f_{1}(1285) u_{tau}$ and $tau^{-} to K^{*-}K^{0}_{S} pi^{0} u_{tau}$ are observed.
