1,089 research outputs found
Positive Parity Pentaquarks Pragmatically Predicted
We consider the possibility that the lightest pentaquark is a parity even
state, with one unit of orbital angular momentum. Working within the framework
of a constituent quark model, we show that dominant spin-flavor interactions
render certain parity-even states lighter than any pentaquark with all quarks
in the spatial ground state. For such states, we focus on predicting the mass
and decays of other members of the same SU(3) flavor multiplet. Specifically,
we consider the strangeness -2 cascade pentaquarks, which are relatively immune
to mixing. We take into account flavor SU(3) breaking effects originating from
the strange quark mass as well as from the structure of the spin-flavor
exchange interactions themselves. We predict the lightest cascade pentaquarks
at approximately 1906 MeV, with a full width about 3 times larger than that of
the Theta^+.Comment: 13 pages, 1 figure, 4 tables, Revtex
Collider Signatures of the N=3 Lee-Wick Standard Model
Inspired by the Lee-Wick higher-derivative approach to quantum field theory,
Grinstein, O'Connell, and Wise have illustrated the utility of introducing into
the Standard Model negative-norm states that cancel quadratic divergences in
loop diagrams, thus posing a potential resolution of the hierarchy problem.
Subsequent work has shown that consistency with electroweak precision
parameters requires many of the partner states to be too massive to be detected
at the LHC. We consider the phenomenology of a yet-higher derivative theory
that exhibits three poles in its bare propagators (hence N=3), whose states
alternate in norm. We examine the interference effects of W boson partners on
LHC scattering cross sections, and find that the N=3 LWSM already makes
verifiable predictions at 10 fb^(-1) of integrated luminosity.Comment: 15 pages, 4 PDF figures. Version accepted for publication by JHE
An algorithm for correcting CoRoT raw light curves
We introduce the CoRoT detrend algorithm (CDA) for detrending CoRoT stellar
light curves. The algorithm CDA has the capability to remove random jumps and
systematic trends encountered in typical CoRoT data in a fully automatic
fashion. Since enormous jumps in flux can destroy the information content of a
light curve, such an algorithm is essential. From a study of 1030 light curves
in the CoRoT IRa01 field, we developed three simple assumptions which upon CDA
is based. We describe the algorithm analytically and provide some examples of
how it works. We demonstrate the functionality of the algorithm in the cases of
CoRoT0102702789, CoRoT0102874481, CoRoT0102741994, and CoRoT0102729260. Using
CDA in the specific case of CoRoT0102729260, we detect a candidate exoplanet
around the host star of spectral type G5, which remains undetected in the raw
light curve, and estimate the planetary parameters to be Rp=6.27Re and P=1.6986
days.Comment: 8 pages, 13 figure
Rainfall and land use empirically coupled to forecast landslides in the Esino river basin, central Italy
Abstract. A coupled empirical approach to highlight relationships between rainfall, vegetation segmentation, and landslide occurrence is discussed. To reveal such links, two important rainfall events, which occurred over the Esino river basin in central Italy in November 2013 and May 2014, were analysed. The correlation between rainfall and landslides was evaluated by applying an intensity–duration (ID) threshold method, whereas the correlation between vegetation segmentation and landslides was investigated using morphological spatial pattern analysis (MSPA). This coupled approach represents an attempt to find both timing and location of landslide occurrence through an empirical (black box) analysis. Results showed: (i) the ID minimum threshold proposed in a previous study (Gioia et al., 2015) to be verified as an effective equation to assess the rainfall conditions likely to trigger landslides in the study area ("when"), and (ii) the core areas and the fragmented vegetation structures defined by the MSPA to be the most affected by slope failures ("where"). These encouraging findings prompt additional testing and the application of such a coupled empirical approach so that it is possible to achieve an integrated basis for landslide forecasting
Holographic Electroweak Symmetry Breaking from D-branes
We observe several interesting phenomena in a technicolor-like model of
electroweak symmetry breaking based on the D4-D8-D8bar system of Sakai and
Sugimoto. The benefit of holographic models based on D-brane configurations is
that both sides of the holographic duality are well understood. We find that
the lightest technicolor resonances contribute negatively to the
Peskin-Takeuchi S-parameter, but heavy resonances do not decouple and lead
generically to large, positive values of S, consistent with standard estimates
in QCD-like theories. We study how the S parameter and the masses and decay
constants of the vector and axial-vector techni-resonances vary over a
one-parameter family of D8-brane configurations. We discuss possibilities for
the consistent truncation of the theory to the first few resonances and suggest
some generic predictions of stringy holographic technicolor models.Comment: REVTeX, 25 pages, 8 eps figures, version published in PR
Deconstructing Superconductivity
We present a dimensionally deconstructed model of an s-wave holographic
superconductor. The 2+1 dimensional model includes multiple charged Cooper pair
fields and neutral exciton fields that have interactions governed by hidden
local symmetries. We derive AdS/CFT-like relations for the current and charge
density in the model, and we analyze properties of the Cooper pair condensates
and the complex conductivity.Comment: 24 pages, 10 eps figures. v2: Sign conventions clarified, references
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Decays of l=1 Baryons to Delta gamma
Recently we considered the electromagnetic decays of the orbitally-excited
SU(6) 70-plet baryons in large-N_c QCD, fitting to the helicity amplitudes
measured in photoproduction experiments. Using the results of this analysis, we
predict the helicity amplitudes for the decays N^* \to \Delta\gamma and
\Delta^* \to \Delta\gamma. These decays can be studied at a number of new
experimental facilities, and thus provide another nontrivial test of the lowest
order large-N_c predictions.Comment: 12 pages LaTeX, one EPS figur
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