Digging for biosynthetic dark matter.

An analysis of bacterial communities in soil samples from around the world reveals unexplored diversity in biosynthetic enzymes

Measurement of the rapidity-even dipolar flow in Pb-Pb collisions with the ATLAS detector

The rapidity-even dipolar flow v1 associated with dipole asymmetry in the initial geometry is measured over a broad range in transverse momentum 0.5 GeV<pT<9 GeV, and centrality (0-50)% in Pb-Pb collisions at sqrt(s_NN)=2.76 TeV, recorded by the ATLAS experiment at the LHC. The v1 coefficient is determined via a two-component fit of the first order Fourier coefficient, v_{1,1}= cos \Delta\phi, of two-particle correlations in azimuthal angle \Delta\phi=\phi_a-\phi_b as a function of pT^a and pT^b. This fit is motivated by the finding that the pT dependence of v_{1,1}(pT^a,pT^b) data are consistent with the combined contributions from a rapidity-even v1 and global momentum conservation. The magnitude of the extracted momentum conservation component suggests that the system conserving momentum involves only a subset of the event (spanning about 3 units in \eta in central collisions). The extracted v1 is observed to cross zero at pT~1.0 GeV, reaches a maximum at 4-5 GeV with a value comparable to that for v3, and decreases at higher pT. Interestingly, the magnitude of v1 at high pT exceeds the value of the v3 in all centrality interval and exceeds the value of v2 in central collisions. This behavior suggests that the path-length dependence of energy loss and initial dipole asymmetry from fluctuations corroborate to produce a large dipolar anisotropy for high pT hadrons, making the v1 a valuable probe for studying the jet quenching phenomena.Comment: 9 pages, 6 figures. Proceedings for the 28th Winter Workshop on Nuclear Dynamics, Dorado Del Mar, Puerto Rico, United States Of America, 7 - 14 Apr 201

Color-singlet relativistic correction to inclusive J/ψJ/\psi production associated with light hadrons at BB factories

We study the first-order relativistic correction to the associated production of $J/\psi$ with light hadrons at $B$ factory experiments at $\sqrt{s}=10.58$ GeV, in the context of NRQCD factorization. We employ a strategy for NRQCD expansion that slightly deviates from the orthodox doctrine, in that the matching coefficients are not truly of ``short-distance" nature, but explicitly depend upon physical kinematic variables rather than partonic ones. Our matching method, with validity guaranteed by the Gremm-Kapustin relation, is particularly suited for the inclusive quarkonium production and decay processes with involved kinematics, exemplified by the process $e^+e^-\to J/\psi+gg$ considered in this work. Despite some intrinsic ambiguity affiliated with the order-$v^2$ NRQCD matrix element, if we choose its value as what has been extracted from a recent Cornell-potential-model-based analysis, including the relative order-$v^2$ effect is found to increase the lowest-order prediction for the integrated $J/\psi$ cross section by about 30\%, and exert a modest impact on $J/\psi$ energy, angular and polarization distributions except near the very upper end of the $J/\psi$ energy. The order-$v^2$ contribution to the energy spectrum becomes logarithmically divergent at the maximum of $J/\psi$ energy. A consistent analysis may require that these large end-point logarithms be resummed to all orders in $\alpha_s$.Comment: v2; 41 pages, 5 figures; references added, Section VI and Appendix B expande