STRUCTURE OF SOUTH CENTRAL AGRICULTURAL PRODUCTION

Using a dual economic specification of a multiproduct technology, the structure of agricultural production was tested for five South Central states (Texas, Oklahoma, Arkansas, Mississippi, and Louisiana). A comprehensive set of output supplies and input demands comprised the estimation equations in each state. Evidence of nonjoint production in a subset of commodities was detected in four of the five states. Several commodities also satisfied sufficient conditions for consistent aggregations. However, the specific outputs satisfying each structural property varied by state. Sufficient conditions for consistent geographic aggregation across the states were not satisfied. These results provide empirical guidance and important cautions for legitimately simplifying state-level model specifications of southern agricultural production.Industrial Organization,

Pedestal and Peak Structure in Jet Correlation

We study the characteristics of correlation between particles in jets produced in heavy-ion collisions. In the framework of parton recombination we calculate the $\eta$ and $\phi$ distributions of a pion associated with a trigger particle. The origin of the pedestal in $\Delta\eta$ is related to the longitudinal expansion of the thermal partons that are enhanced by the energy loss of hard partons traversing the bulk medium. The peaks in $\Delta\eta$ and $\Delta\phi$ are related to the same angular spread of the shower partons in a jet cone. No artificial short- or long-range correlations are put in by hand. A large part of the correlation between hadrons in jets is due to the correlation among the shower partons arising from momentum conservation. Recombination between thermal and shower partons dominates the correlation characterisitics in the intermediate $p_T$ region.Comment: 14 pages in LaTex and 2 figures in ep

Effects of Minijets on Hadronic Spectra and Azimuthal Harmonics in Au-Au Collisions at 200 GeV

The production of hadrons in heavy-ion collisions at RHIC in the low transverse-momentum ($p_T$) region is investigated in the recombination model with emphasis on the effects of minijets on the azimuthal anisotropy. Since the study is mainly on the hadronization of partons at late time, the fluid picture is not used to trace the evolution of the system. The inclusive distributions at low $p_T$ are determined as the recombination products of thermal partons. The $p_T$ dependencies of both pion and proton have a common exponential factor apart from other dissimilar kinematic and resonance factors, because they are inherited from the same pool of thermal partons. Instead of the usual description based on hydrodynamics, the azimuthal anisotropy of the produced hadrons is explained as the consequence of the effects of minijets, either indirectly through the recombination of enhanced thermal partons in the vicinity of the trajectories of the semihard partons, or directly through thermal-shower recombination. Although our investigation is focussed on the single-particle distribution at midrapidity, we give reasons why a component in that distribution can be identified with the ridge, which together with the second harmonic $v_2$ is due to the semihard partons created near the medium surface that lead to calculable anisotropy in $\phi$. It is shown that the higher azimuthal harmonics, $v_n$, can also be well reproduced without reference to flow. The $p_T$ and centrality dependencies of the higher harmonics are prescribed by the interplay between TT and TS recombination components. The implication of the success of this drastic departure from the conventional approach is discussed.Comment: 28 pages and 8 figures, more discussions and references adde

Boson Sampling from Gaussian States

We pose a generalized Boson Sampling problem. Strong evidence exists that such a problem becomes intractable on a classical computer as a function of the number of Bosons. We describe a quantum optical processor that can solve this problem efficiently based on Gaussian input states, a linear optical network and non-adaptive photon counting measurements. All the elements required to build such a processor currently exist. The demonstration of such a device would provide the first empirical evidence that quantum computers can indeed outperform classical computers and could lead to applications

Optimal measurements for relative quantum information

We provide optimal measurement schemes for estimating relative parameters of the quantum state of a pair of spin systems. We prove that the optimal measurements are joint measurements on the pair of systems, meaning that they cannot be achieved by local operations and classical communication. We also demonstrate that in the limit where one of the spins becomes macroscopic, our results reproduce those that are obtained by treating that spin as a classical reference direction.Comment: 6 pages, 1 figure, published versio

Gauge Orbit Types for Theories with Classical Compact Gauge Group

We determine the orbit types of the action of the group of local gauge transformations on the space of connections in a principal bundle with structure group O(n), SO(n) or $Sp(n)$ over a closed, simply connected manifold of dimension 4. Complemented with earlier results on U(n) and SU(n) this completes the classification of the orbit types for all classical compact gauge groups over such space-time manifolds. On the way we derive the classification of principal bundles with structure group SO(n) over these manifolds and the Howe subgroups of SO(n).Comment: 57 page

ISO Detection of CO⁺ toward the protostar IRAS 16293-2422

In this letter we report the detection of eight high-N rotational transitions of CO+ towards a low mass protostar, IRAS 16293-2422. The source was observed with the Long Wavelength Spectrometer on board the Infrared Space Observatory. This is the first time that CO+ has been detected in a low luminosity source and the first time that high-N lines have been detected in any source. The detection of these lines was not predicted by models and consequently, their interpretation is a challenge. We discuss the possibility that the observed CO+ emission originates in the dense inner regions illuminated by the UV field created in the accretion shock (formed by infalling material), and conclude that this is an improbable explanation. We have also considered the possibility that a strong, dissociative J-shock at ~ 500 AU from the star is the origin of the CO+ emission. This model predicts CO+ column densities in rough agreement with the observations if the magnetic field is ~ 1 mG and the shock velocity is 100 km s-1

Detection of CO⁺ with ISO towards the protostar IRAS16293-242

We observed the low luminosity (and low mass) protostar IRAS16293-2422 with the Long Wavelength Spectrometer on board the Infrared Space Observatory. The observed line spectrum is very reach and shows transitions of several molecules and atoms. Here we report the detection of eight high-N rotational transitions of CO+. This is the first time that CO+ has been detected in a low luminosity source and the first time that high-N lines have been detected in any source. The detection of these lines was not predicted by models and consequently, their interpretation is a challenge. We discuss the possibility that the observed CO+ emission originates in the dense inner regions illuminated by the UV field created in the accretion shock (formed by infalling material), and conclude that this is an improbable explanation. We have also considered the possibility that a strong, dissociative J-shock at ~500 AU from the star is the origin of the CO+ emission. This model predicts CO+ column densities in rough agreement with the observations if the magnetic field is ~1 mG and the shock velocity is 100 km s-1

Dihadron Correlation in Jets Produced in Heavy-Ion Collisions

The difference between the structures of jets produced in heavy-ion and hadronic collisions can best be exhibited in the correlations between particles within those jets. We study the dihadron correlations in jets in the framework of parton recombination. Two types of triggers, $\pi^+$ and proton, are considered. It is shown that the recombination of thermal and shower partons makes the most important contribution to the spectra of the associated particles at intermediate $p_T$. In $pp$ collisions the only significant contribution arises from shower-shower recombination, which is negligible in heavy-ion collisions. Moments of the associated-particle distributions are calculated to provide simple summary of the jet structures for easy comparison with experiments.Comment: 24 pages in Latex + 5 figure

Further results on the cross norm criterion for separability

In the present paper the cross norm criterion for separability of density matrices is studied. In the first part of the paper we determine the value of the greatest cross norm for Werner states, for isotropic states and for Bell diagonal states. In the second part we show that the greatest cross norm criterion induces a novel computable separability criterion for bipartite systems. This new criterion is a necessary but in general not a sufficient criterion for separability. It is shown, however, that for all pure states, for Bell diagonal states, for Werner states in dimension d=2 and for isotropic states in arbitrary dimensions the new criterion is necessary and sufficient. Moreover, it is shown that for Werner states in higher dimensions (d greater than 2), the new criterion is only necessary.Comment: REVTeX, 19 page