1,249 research outputs found
Hadronization corrections to helicity components of the fragmentation function
In the hadronic decays of Z, gluon emission leads to the appearance of the
longitudinal component of the fragmentation function, F_L. Measurement of F_L
and the transverse component, F_T, could thus provide an insight into the gluon
fragmentation function. However, hadronization corrections at low x can be
significant. Here we present a method of accounting for such corrections, using
the JETSET event generator as illustration.Comment: 11 pages, 5 figure
Endogenous Taxation in Ongoing Internal Conflict: The Case of Colombia
Recent empirical evidence suggests an ambiguous relationship between internal conflicts, state capacity, and tax performance. In theory, internal conflict should create strong incentives for governments to develop the fiscal capacity necessary to defeat rivals. We argue that one reason that this does not occur is because internal conflict enables groups with de facto power to capture local fiscal and property rights institutions. We test this mechanism in Colombia using data on tax performance and property rights institutions at the municipal level. Municipalities affected by internal conflict have tax institutions consistent with the preferences of the parties dominating local violence. Those suffering more right-wing violence feature more land formalization and higher property tax revenues. Municipalities with substantial left-wing guerrilla violence collect less tax revenue and witness less land formalization. Our findings provide systematic evidence that internal armed conflict helps interest groups capture municipal institutions for their own private benefit, impeding state-building. Copyright © American Political Science Association 2018
New Forms of Deuteron Equations and Wave Function Representations
A recently developed helicity basis for nucleon-nucleon (NN) scattering is
applied to th e deuteron bound state. Here the total spin of the deuteron is
treated in such a helicity representation. For the bound state, two sets of two
coupled eigenvalue equations are developed, where the amplitudes depend on two
and one variable, respectively. Numerical illustrations based on the realistic
Bonn-B NN potential are given. In addition, an `operator form' of the deuteron
wave function is presented, and several momentum dependent spin densities are
derived and shown, in which the angular dependence is given analytically.Comment: 19 pages (Revtex), 9 fig
Tobacco abuse and its health effect
Tobacco smoking is still one of the most important risk factor for Respiratory and cardiovascular diseases and an estimated 90% of causes of lung cancer are attributable to Tobacco smocking and equally 90% of peripheral vascular disease in non-diabetic population is attributable to Tobacco smoking, despite the health effect there is disturbing figures of people who take up smoking habit daily and increase level of failed quit smoking attempts.Environment and genetics still plays major role, and various forms of tobacco is used worldwide and its health consequence has been highlighted. Monitoring tobacco use and prevention policies through effective tax laws is paramount to reduction of the tobacco health effects in our environments.Keywords: Tobacco abuse, cigarrete smoking, health effec
Experimental demonstration of quantum memory for light
The information carrier of today's communications, a weak pulse of light, is
an intrinsically quantum object. As a consequence, complete information about
the pulse cannot, even in principle, be perfectly recorded in a classical
memory. In the field of quantum information this has led to a long standing
challenge: how to achieve a high-fidelity transfer of an independently prepared
quantum state of light onto the atomic quantum state? Here we propose and
experimentally demonstrate a protocol for such quantum memory based on atomic
ensembles. We demonstrate for the first time a recording of an externally
provided quantum state of light onto the atomic quantum memory with a fidelity
up to 70%, significantly higher than that for the classical recording. Quantum
storage of light is achieved in three steps: an interaction of light with
atoms, the subsequent measurement on the transmitted light, and the feedback
onto the atoms conditioned on the measurement result. Density of recorded
states 33% higher than that for the best classical recording of light on atoms
is achieved. A quantum memory lifetime of up to 4 msec is demonstrated.Comment: 22 pages (double line spacing) incl. supplementary information, 4
figures, accepted for publication in Natur
Quantum teleportation between light and matter
Quantum teleportation is an important ingredient in distributed quantum
networks, and can also serve as an elementary operation in quantum computers.
Teleportation was first demonstrated as a transfer of a quantum state of light
onto another light beam; later developments used optical relays and
demonstrated entanglement swapping for continuous variables. The teleportation
of a quantum state between two single material particles (trapped ions) has now
also been achieved. Here we demonstrate teleportation between objects of a
different nature - light and matter, which respectively represent 'flying' and
'stationary' media. A quantum state encoded in a light pulse is teleported onto
a macroscopic object (an atomic ensemble containing 10^12 caesium atoms).
Deterministic teleportation is achieved for sets of coherent states with mean
photon number (n) up to a few hundred. The fidelities are 0.58+-0.02 for n=20
and 0.60+-0.02 for n=5 - higher than any classical state transfer can possibly
achieve. Besides being of fundamental interest, teleportation using a
macroscopic atomic ensemble is relevant for the practical implementation of a
quantum repeater. An important factor for the implementation of quantum
networks is the teleportation distance between transmitter and receiver; this
is 0.5 metres in the present experiment. As our experiment uses propagating
light to achieve the entanglement of light and atoms required for
teleportation, the present approach should be scalable to longer distances.Comment: 23 pages, 8 figures, incl. supplementary informatio
Threshold Effects on Heavy Quark Production in Interactions
The exchange of gluons between heavy quarks produced in interactions
results in an enhancement of their production near threshold. We study QCD
threshold effects in collisions. The results are relevant to
heavy quark production by beamstrahlung and laser back-scattering in future
linear collider experiments. Detailed predictions for top, bottom and charm
production are presented.Comment: 26 pages, 12 figures available in ps upon request, revtex, MAD/PH/701
(revised version
Relativistic Corrections to the Triton Binding Energy
The influence of relativity on the triton binding energy is investigated. The
relativistic three-dimensional version of the Bethe-Salpeter equation proposed
by Blankenbecler and Sugar (BbS) is used. Relativistic (non-separable)
one-boson-exchange potentials (constructed in the BbS framework) are employed
for the two-nucleon interaction. In a 34-channel Faddeev calculation, it is
found that relativistic effects increase the triton binding energy by about 0.2
MeV. Including charge-dependence (besides relativity), the final triton binding
energy predictions are 8.33 and 8.16 MeV for the Bonn A and B potential,
respectively.Comment: 25 pages of text (latex), 1 figure (not included, available upon
request
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