22,387 research outputs found
Reply to the Comment on `Deterministic Single-Photon Source for Distributed Quantum Networking'
Reply to the comment of H. J. Kimble [quant-ph/0210032] on the experiment
realizing a "deterministic single-photon source for distributed quantum
networking" by Kuhn, Hennrich, and Rempe [Phys. Rev. Lett. 89, 067901 (2002),
quant-ph/0204147].Comment: 1 page 1 figur
Summing up Subleading Sudakov Logarithms
We apply the strategy of regions within dimensional regularization to find
functions involved in evolution equations which govern the asymptotic dynamics
of the Abelian form factor and four-fermion amplitude in the SU(N) gauge theory
in the Sudakov limit up to the next-to-leading logarithmic approximation. The
results are used for the analysis of the dominant electroweak corrections to
the fermion-antifermion pair production in the annihilation at high
energy.Comment: 17 pages LaTeX, missprins corrected, references adde
Perspectives for the radiative return at meson factories
The measurement of the pion form factor and, more generally, of the cross
section for electron-positron annihilation into hadrons through the radiative
return has become an important task for high luminosity colliders such as the
Phi- or B-meson factories. This quantity is crucial for predictions of the
hadronic contributions to the anomalous magnetic moment of the muon, and to the
running of the electromagnetic coupling. But the radiative return opens the
possibility of many other physical applications. The physics potential of this
method at high luminosity meson factories is discussed, the last upgraded
version of the event generator PHOKHARA is presented, and future developments
are highlighted.Comment: Presented at SIGHAD03: Worskhop on Hadronic Cross Section at Low
Energy, Pisa,Italy, October 8th-10th, 200
Next-to-Next-to-Leading Electroweak Logarithms for W-Pair Production at LHC
We derive the high energy asymptotic of one- and two-loop corrections in the
next-to-next-to-leading logarithmic approximation to the differential cross
section of -pair production at the LHC. For large invariant mass of the
W-pair the (negative) one-loop terms can reach more than 40%, which are
partially compensated by the (positive) two-loop terms of up to 10%.Comment: 23 pages, 9 figures, added explanations in section 3, corrected typos
and figures 7, 8,
Explaining Violation Traces with Finite State Natural Language Generation Models
An essential element of any verification technique is that of identifying and
communicating to the user, system behaviour which leads to a deviation from the
expected behaviour. Such behaviours are typically made available as long traces
of system actions which would benefit from a natural language explanation of
the trace and especially in the context of business logic level specifications.
In this paper we present a natural language generation model which can be used
to explain such traces. A key idea is that the explanation language is a CNL
that is, formally speaking, regular language susceptible transformations that
can be expressed with finite state machinery. At the same time it admits
various forms of abstraction and simplification which contribute to the
naturalness of explanations that are communicated to the user
Polarization-controlled single photons
Vacuum-stimulated Raman transitions are driven between two magnetic substates
of a rubidium-87 atom strongly coupled to an optical cavity. A magnetic field
lifts the degeneracy of these states, and the atom is alternately exposed to
laser pulses of two different frequencies. This produces a stream of single
photons with alternating circular polarization in a predetermined
spatio-temporal mode. MHz repetition rates are possible as no recycling of the
atom between photon generations is required. Photon indistinguishability is
tested by time-resolved two-photon interference.Comment: 4 pages, 3 figure
Resummation of Threshold, Low- and High-Energy Expansions for Heavy-Quark Correlators
With the help of the Mellin-Barnes transform, we show how to simultaneously
resum the expansion of a heavy-quark correlator around q^2=0 (low-energy), q^2=
4 m^2 (threshold, where m is the quark mass) and q^2=-\infty (high-energy) in a
systematic way. We exemplify the method for the perturbative vector correlator
at O(alpha_s^2) and O(alpha_s^3). We show that the coefficients, Omega(n), of
the Taylor expansion of the vacuum polarization function in terms of the
conformal variable \omega admit, for large n, an expansion in powers of 1/n (up
to logarithms of n) that we can calculate exactly. This large-n expansion has a
sign-alternating component given by the logarithms of the OPE, and a fixed-sign
component given by the logarithms of the threshold expansion in the external
momentum q^2.Comment: 27 pages, 8 figures. We fix typos in Eqs. (18), (27), (55) and (56).
Results unchange
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