44,061 research outputs found
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 production associated with light hadrons at factories
We study the first-order relativistic correction to the associated production
of with light hadrons at factory experiments at
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
considered in this work. Despite some intrinsic ambiguity affiliated with the
order- 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- effect is found to increase the lowest-order prediction
for the integrated cross section by about 30\%, and exert a modest
impact on energy, angular and polarization distributions except near
the very upper end of the energy. The order- contribution to the
energy spectrum becomes logarithmically divergent at the maximum of
energy. A consistent analysis may require that these large end-point logarithms
be resummed to all orders in .Comment: v2; 41 pages, 5 figures; references added, Section VI and Appendix B
expande
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