251,669 research outputs found
Deformations of Closed Strings and Topological Open Membranes
We study deformations of topological closed strings. A well-known example is
the perturbation of a topological closed string by itself, where the
associative OPE product is deformed, and which is governed by the WDVV
equations. Our main interest will be closed strings that arise as the boundary
theory for topological open membranes, where the boundary string is deformed by
the bulk membrane operators. The main example is the topological open membrane
theory with a nonzero 3-form field in the bulk. In this case the Lie bracket of
the current algebra is deformed, leading in general to a correction of the
Jacobi identity. We identify these deformations in terms of deformation theory.
To this end we describe the deformation of the algebraic structure of the
closed string, given by the BRST operator, the associative product and the Lie
bracket. Quite remarkably, we find that there are three classes of deformations
for the closed string, two of which are exemplified by the WDVV theory and the
topological open membrane. The third class remains largely mysterious, as we
have no explicit example.Comment: 50 pages, LaTeX; V2: minor changes, 2 references added, V3: typos
corrected, signs added, modified discussion on higher correlator
A Bi-Hamiltonian Formulation for Triangular Systems by Perturbations
A bi-Hamiltonian formulation is proposed for triangular systems resulted by
perturbations around solutions, from which infinitely many symmetries and
conserved functionals of triangular systems can be explicitly constructed,
provided that one operator of the Hamiltonian pair is invertible. Through our
formulation, four examples of triangular systems are exhibited, which also show
that bi-Hamiltonian systems in both lower dimensions and higher dimensions are
many and varied. Two of four examples give local 2+1 dimensional bi-Hamiltonian
systems and illustrate that multi-scale perturbations can lead to
higher-dimensional bi-Hamiltonian systems.Comment: 16 pages, to appear in J. Math. Phy
Triplicity of Quarks and Leptons
Quarks come in three colors and have electric charges in multiples of
one-third. There are also three families of quarks and leptons. Whereas the
first two properties can be understood in terms of unification symmetries such
as SU(5), SO(10), or E_6, why there should only be three families remains a
mystery. I propose how all three properties involving the number three are
connected in a fivefold application of the gauge symmetry SU(3).Comment: 10 pages, including 2 figure
A User-Focused Reference Model for Wireless Systems Beyond 3G
This whitepaper describes a proposal from Working Group 1, the Human Perspective of the Wireless World, for a user-focused reference model for systems beyond 3G. The general structure of the proposed model involves two "planes": the Value Plane and the Capability Plane. The characteristics of these planes are discussed in detail and an example application of the model to a specific scenario for the wireless world is provided
New "Square Root" Model of Lepton Family Cyclic Symmetry
Following the newly formulated notion of form invariance of the neutrino mass
matrix, a complete model of leptons is constructed. It is based on a specific
unitary 3 X 3 matrix U in family space, such that U^2 is the simple discrete
symmetry nu_e to -nu_e, nu_mu to nu_tau. Thus U also generates the cyclic group
Z_4. The charged-lepton mass matrix is nearly diagonal while the neutrino mass
matrix is of the form suitable for explaining maximal (large) mixing in
atmospheric (solar) neutrino oscillations in the context of three nearly
degenerate neutrino masses. Observable lepton flavor violation is predicted.
Quarks may be treated in the same way as the charged leptons.Comment: 10 pages, no figur
X-ray background and its correlation with the 21 cm signal
We use high resolution hydrodynamical simulations to study the contribution
to the X-ray background from high- energetic sources, such as X-ray
binaries, accreting nuclear black holes and shock heated interstellar medium.
Adopting the model discussed in Eide et al. (2018), we find that these X-ray
sources during the Epoch of Reionization (EoR) contribute less than a few
percent of the unresolved X-ray background. The same sources contribute to less
than 2\% of the measured angular power spectrum of the fluctuations of
the X-ray background. The outputs of radiative transfer simulations modeling
the EoR are used to evaluate the cross-correlations of X-ray background with
the 21~cm signal from neutral hydrogen. Such correlation could be used to
confirm the origin of the 21 cm signal, as well as give information on the
properties of the X-ray sources during the EoR. We find that the correlations
are positive during the early stages of reionization when most of the hydrogen
is neutral, while they become negative when the intergalactic medium gets
highly ionized, with the transition from positive to negative depending on both
the X-ray model and the scale under consideration. With {\tt SKA} as the
reference instrument for the 21~cm experiment, the predicted S/N for such
correlations is if the corresponding X-ray survey is only able to resolve
and remove X-ray sources with observed flux , while the cumulative S/N from to at
is if sources with observed flux are detected.Comment: 9 pages, 8 figure
Nearly Mass-Degenerate Majorana Neutrinos: Double Beta Decay and Neutrino Oscillations
Assuming equal tree-level Majorana masses for the standard-model neutrinos,
either from the canonical seesaw mechanism or from a heavy scalar triplet, I
discuss how their radiative splitting may be relevant to neutrinoless double
beta decay and neutrino oscillations.Comment: 12 pages, including 4 figures, talk at NANP9
Altruism and Voluntary Provision of Public Goods.
We study how people's predisposition towards altruism, as measured by tools developed by psychologists, affects their behaviour in a voluntary contributions public good environment. Earlier experiments provide evidence against the strong free rider hypothesis; however, contributions to the public good decrease with repetition. We investigate whether a high level of contributions can be sustained in groups of subjects who have been pre-selected on the basis of their altruistic inclinations. In the first stage of the experiment, each subject responds to a psychology questionnaire that measures various dimensions of one's personality. The subjects are then matched in groups according to their altruism scores, and engage in a voluntary contribution game. We consider whether the levels and dynamics of group contributions differ significantly between the groups with altruists and non-altruists. We find that subjects' altruism has a weak but positive effect on group behaviour in the public good game.PUBLIC OWNERSHIP ; BEHAVIOUR ; GAMES
Dissipate locally, couple globally: a sharp transition from decoupling to infinite range coupling in Josephson arrays with on-site dissipation
We study the T=0 normal to superconducting transition of Josephson arrays
with {\it on-site} dissipation. A perturbative renormalization group solution
is given. Like the previously studied case of {\it bond} dissipation (BD), this
is a "floating" to coupled (FC) phase transition. {\it Unlike} the BD
transition, at which {\it only} nearest-neighbor couplings become relevant,
here {\it all} inter-grain couplings, out to {\it infinitely} large distances,
do so simultaneously. We predict, for the first time in an FC transition, a
diverging spatial correlation length. Our results show the robustness of
floating phases in dissipative quantum systems.Comment: 7+ pages, 3 eps figures, Europhysics Letters preprint format, as
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