358 research outputs found
μ s isomers of Nd 158,160
The neutron-rich nuclei Nd158,160 have been studied via delayed γ-ray spectroscopy of μs isomeric states at the RIBF facility, RIKEN. These nuclei were produced following the projectile fission of a 345 AMeVU238 beam and delayed γ rays were detected by the EURICA cluster Ge array. The isomeric states have measured half-lives of 339(20) ns and 1.63(21) μs for Nd158 and Nd160, respectively. From the observed γ decays and the systematics of levels in the neighboring Nd isotopes first level schemes were constructed for these nuclei. The isomeric states of Nd158,160 have been assigned spins of (6-) and (4-), with proposed ν5/2[523] - ν7/2[633] and ν1/2[521] - ν7/2[633] configurations, respectively. © 2016 American Physical Society
Nonlinear optical interactions in silicon waveguides
The strong nonlinear response of silicon photonic nanowire waveguides allows for the integration of nonlinear optical functions on a chip. However, the detrimental nonlinear optical absorption in silicon at telecom wavelengths limits the efficiency of many such experiments. In this review, several approaches are proposed and demonstrated to overcome this fundamental issue. By using the proposed methods, we demonstrate amongst others supercontinuum generation, frequency comb generation, a parametric optical amplifier, and a parametric optical oscillator
Orbifold projection in supersymmetric QCD at N_f\leq N_c
Supersymmetric orbifold projection of N=1 SQCD with relatively small number
of flavors (not larger than the number of colors) is considered. The purpose is
to check whether orbifolding commutes with the infrared limit. On the one hand,
one considers the orbifold projection of SQCD and obtains the low-energy
description of the resulting theory. On the other hand, one starts with the
low-energy effective theory of the original SQCD, and only then perfoms
orbifolding. It is shown that at finite N_c the two low-energy theories
obtained in these ways are different. However, in the case of stabilized
run-away vacuum these two theories are shown to coincide in the large N_c
limit. In the case of quantum modified moduli space, topological solitons
carrying baryonic charges are present in the orbifolded low-energy theory.
These solitons may restore the correspondence between the two theories provided
that the soliton mass tends to zero in the large N_c limit.Comment: 10 pages; misprint corrected, reference adde
The general Leigh-Strassler deformation and integrability
The success of the identification of the planar dilatation operator of N=4
SYM with an integrable spin chain Hamiltonian has raised the question if this
also is valid for a deformed theory. Several deformations of SYM have recently
been under investigation in this context. In this work we consider the general
Leigh-Strassler deformation. For the generic case the S-matrix techniques
cannot be used to prove integrability. Instead we use R-matrix techniques to
study integrability. Some new integrable points in the parameter space are
found.Comment: 22 pages, 8 figures, reference adde
The Bethe Ansatz for Z_S Orbifolds of N=4 Super Yang-Mills Theory
Worldsheet techniques can be used to argue for the integrability of string
theory on AdS_5xS^5/Z_S, which is dual to the strongly coupled Z_S-orbifold of
N=4 SYM. We analyze the integrability of these field theories in the
perturbative regime and construct the relevant Bethe equations.Comment: 16 page
Perturbative Search for Fixed Lines in Large N Gauge Theories
The logarithmic running of marginal double-trace operators is a general
feature of 4-d field theories containing scalar fields in the adjoint or
bifundamental representation. Such operators provide leading contributions in
the large N limit; therefore, the leading terms in their beta functions must
vanish for a theory to be large N conformal. We calculate the one-loop beta
functions in orbifolds of the N=4 SYM theory by a discrete subgroup Gamma of
the SU(4) R-symmetry, which are dual to string theory on AdS_5 x S^5/Gamma. We
present a general strategy for determining whether there is a fixed line
passing through the origin of the coupling constant space. Then we study in
detail some classes of non-supersymmetric orbifold theories, and emphasize the
importance of decoupling the U(1) factors. Among our examples, which include
orbifolds acting freely on the S^5, we do not find any large N
non-supersymmetric theories with fixed lines passing through the origin.
Connection of these results with closed string tachyon condensation in AdS_5 x
S^5/Gamma is discussed.Comment: 31 pages, 4 figures, latex v2: Clarifications and reference adde
Spiky strings and single trace operators in gauge theories
We consider single trace operators of the form O_{m_1 ... m_n} = tr D_+^{m_1}
F ... D_+^{m_n} F which are common to all gauge theories. We argue that, when
all m_i are equal and large, they have a dual description as strings with
cusps, or spikes, one for each field F. In the case of N=4 SYM, we compute the
energy as a function of angular momentum by finding the corresponding solutions
in AdS_5 and compare with a 1-loop calculation of the anomalous dimension. As
in the case of two spikes (twist two operators), there is agreement in the
functional form but not in the coupling constant dependence. After that, we
analyze the system in more detail and find an effective classical mechanics
describing the motion of the spikes. In the appropriate limit, it is the same
(up to the coupling constant dependence) as the coherent state description of
linear combinations of the operators O_{m_1 ... m_n} such that all m_i are
equal on average. This agreement provides a map between the operators in the
boundary and the position of the spikes in the bulk. We further suggest that
moving the spikes in other directions should describe operators with
derivatives other than D_+ indicating that these ideas are quite generic and
should help in unraveling the string description of the large-N limit of gauge
theories.Comment: 23 pages, 5 figures. v2: References and comments adde
Classical integrability in the BTZ black hole
Using the fact the BTZ black hole is a quotient of AdS_3 we show that
classical string propagation in the BTZ background is integrable. We construct
the flat connection and its monodromy matrix which generates the non-local
charges. From examining the general behaviour of the eigen values of the
monodromy matrix we determine the set of integral equations which constrain
them. These equations imply that each classical solution is characterized by a
density function in the complex plane. For classical solutions which correspond
to geodesics and winding strings we solve for the eigen values of the monodromy
matrix explicitly and show that geodesics correspond to zero density in the
complex plane. We solve the integral equations for BMN and magnon like
solutions and obtain their dispersion relation. Finally we show that the set of
integral equations which constrain the eigen values of the monodromy matrix can
be identified with the continuum limit of the Bethe equations of a twisted
SL(2, R) spin chain at one loop.Comment: 45 pages, Reference added, typos corrected, discussion on geodesics
improved to include all geodesic
Change of nuclear configurations in the neutrinoless double- decay of Te Xe and Xe Ba
The change in the configuration of valence protons between the initial and
final states in the neutrinoless double- decay of Te
Xe and of Xe Ba has been
determined by measuring the cross sections of the (,He) reaction with
101-MeV deuterons. Together with our recent determination of the relevant
neutron configurations involved in the process, a quantitative comparison with
the latest shell-model and interacting-boson-model calculations reveals
significant discrepancies. These are the same calculations used to determine
the nuclear matrix elements governing the rate of neutrinoless double-
decay in these systems.Comment: 10 pages, 4 figures, 9 table
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