178 research outputs found
A new interpretation for the and the prediction of novel exotic charmed mesons
In this manuscript we study the vector - vector interaction within the hidden
gauge formalism in a coupled channel unitary approach. In the sector
we get a pole in the T-matrix around MeV that we identify
with the , coupling strongly to the
(()) channels. In addition we obtain resonances in
other exotic sectors which have not been studied before such as ,
and . This 'flavor-exotic' states are interpreted as
, and molecular states but have not been
observed yet. In total we obtain nine states with different spin, isospin,
charm and strangeness of non and character, which have been
reported before
Two-photon and one photon-one vector meson decay widths of the , , , , and
We calculate the radiative decay widths, two-photon () and one
photon-one vector meson (), of the dynamically generated resonances
from vector meson-vector meson interaction in a unitary approach based on the
hidden-gauge Lagrangians. In the present paper we consider the following
dynamically generated resonances: , , ,
, , two strangeness=0 and isospin=1 states, and two
strangeness=1 and isospin=1/2 states. For the and we
reproduce the previous results for the two-photon decay widths and further
calculate their one photon-one vector decay widths. For the and
the calculated two-photon decay widths are found to be consistent
with data. The , and decay widths of
the , , , are compared with the
results predicted by other approaches. The and
decay rates of the are also calculated and compared with the
results obtained in the framework of the covariant oscillator quark model. The
results for the two states with strangeness=0, isospin=1 and two states with
strangeness=1, isospin=1/2 are predictions that need to be tested by future
experiments.Comment: More discussions about the relation between qqbar states and
dynamically generated states; version published in PRD
Charmed baryon Sigmac(2800) as a ND hadronic molecule
The isotriplet Sigmac(2800) baryon with possible quantum numbers J(P) =
1/2(+), 1/2(-) or 3/2(+), 3/2(-) is considered as a hadronic molecule composed
of a nucleon and a D meson. We determine the strong two-body decay widths
Sigmac to Lambdac + pi which are shown to be consistent with current data for
the J(P) = 1/2(+) and J(P) = 3/2(-) assignments.Comment: 8 pages, 2 figure
The X(3872) and other X,Y,Z Resonances as Hidden Charm Meson-Meson Molecules
We report on some ideas concerning the nature of the X(3872) resonance and
the need for approximately equal charged and neutral components of . Then we discuss how some hidden charm states are obtained from the
interaction between vector mesons with charm and can be associated to some of
the charmonium-like X,Y,Z states. Finally we discuss how the nature of these
states could be investigated through different types of radiative decay.Comment: Presented at the Charm2010 Workshop, Beijing, Oct. 201
The , , , , and as dynamically generated states from vector meson - vector meson interaction
We report on some recent developments in understanding the nature of the
low-lying mesonic resonances , , ,
, and . In particular we show that these five
resonances can be dynamically generated from vector meson--vector meson
interaction in a coupled-channel unitary approach, which utilizes the
phenomenologically very successful hidden-gauge Lagrangians to produce the
interaction kernel between two vector mesons, which is then unitarized by the
Bethe-Salpeter-equation method. The data on the strong decay branching ratios,
total decay widths, and radiative decay widths of these five states, and on
related decay processes can all be well described by such an approach.
We also make predictions, compare them with the results of earlier studies, and
highlight observables that if measured can be used to distinguish different
pictures of these resonances.Comment: 9 pages; Invited talk at workshop CHIRAL'10, Valencia (Spain), June
21-24, 201
Strong and radiative decays of the scalars f0(980) and a0(980) in a hadronic molecule approach
We analyze the electromagnetic and strong decay properties of the light
scalars a0(980) and f0(980) within a hadronic molecule interpretation. Both
scalars are discussed within a covariant and gauge invariant model which also
allows for finite size effects due to their spatially extended structure in the
K Kbar-bound state picture. Allowing for f0-a0 mixing we also study its
influence on the radiative decays f0/a0 to gamma gamma, f0/a0 to gamma omega,
and f0/a0 to gamma rho as well as the phi production of the f0 and a0.
Furthermore, we apply our formalism to describe the strong f0 to pi pi and a0
to pi eta decay properties.Comment: 16 pages, 6 figures, typos corrected, accepted for publication in
Phys. Rev.
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Silicon Heterojunction Solar Cell Characterization and Optimization Using In Situ and Ex Situ Spectroscopic Ellipsometry
The summary of this report is that: in situ SE gives insight into growth mechanisms and accurate layer thickness; (2) ex situ SE measures completed device structures to determine integrated optical properties; and (3) the combination of in situ and ex situ SE provides a powerful method for pinpointing the effects of processing changes in actual SHJ devices and guiding optimization
Recommended from our members
Silicon Heterojunction Solar Cell Characterization and Optimization Using In Situ and Ex Situ Spectroscopic Ellipsometry: Preprint
We use in-situ and ex-situ spectroscopic ellipsometry to characterize the optical, electronic, and structural properties of individual layers and completed silicon heterojunction devices. The combination of in-situ measurements during thin film deposition with ex-situ measurements of completed devices allows us to understand both the growth dynamics of the materials and the effects of each processing step on material properties. In-situ ellipsometry measurements enable us to map out how the optical properties change with deposition conditions, pointing the way towards reducing the absorption loss and increasing device efficiency. We use the measured optical properties and thickness of the i-, n-, and p-layers in optical device modeling to determine how the material properties affect device performance. Our best solar energy conversion efficiencies are 16.9% for a non-textured, single-sided device with an aluminum back surface field contact on a p-type float zone silicon wafer, and 17.8% for a textured double-sided device on a p-type float zone silicon wafer
A dynamical model for longitudinal wave functions in light-front holographic QCD
We construct a Schrodinger-like equation for the longitudinal wave function
of a meson in the valence qq-bar sector, based on the 't Hooft model for
large-N two-dimensional QCD, and combine this with the usual transverse
equation from light-front holographic QCD, to obtain a model for mesons with
massive quarks. The computed wave functions are compared with the wave function
ansatz of Brodsky and De Teramond and used to compute decay constants and
parton distribution functions. The basis functions used to solve the
longitudinal equation may be useful for more general calculations of meson
states in QCD.Comment: 12 pages, 2 figures, RevTeX 4.1; expanded discussion, with
calculation details moved to appendice
Water first aid is beneficial in humans post-burn: evidence from a bi-national cohort study
Introduction: Reported first aid application, frequency and practices around the world vary greatly. Based primarily on animal and observational studies, first aid after a burn injury is considered to be integral in reducing scar and infection, and the need for surgery. The current recommendation for optimum first aid after burn is water cooling for 20 minutes within three hours. However, compliance with this guideline is reported as poor to moderate at best and evidence exists to suggest that overcooling can be detrimental. This prospective cohort study of a binational burn patient registry examined data collected between 2009 and 2012. The aim of the study was to quantify the magnitude of effects of water cooling first aid after burn on indicators of burn severity in a large human cohort.
Method: The data for the analysis was provided by the Burn Registry of Australia and New Zealand (BRANZ). The application of first aid cooling prior to admission to a dedicated burn service, was analysed for its influence on four outcomes related to injury severity. The patient related outcomes were whether graft surgery occurred, and death while the health system (cost) outcomes included total hospital length of stay and admission to ICU. Robust regression analysis using bootstrapped estimation adjusted using a propensity score was used to control for confounding and to estimate the strength of association with first aid. Dose-response relationships were examined to determine associations with duration of first aid. The influence of covariates on the impact of first aid was assessed.
Results: Cooling was provided before Burn Centre admission for 68% of patients, with at least twenty minutes duration for 46%. The results indicated a reduction in burn injury severity associated with first aid. Patients probability for graft surgery fell by 0.070 from 0.537 (13% reduction) (p = 0.014). The probability for ICU admission fell by 0.084 from 0.175 (48% reduction) (p (p = 0.001). All outcomes except death showed a dose-response relationship with the duration of first aid. The size of burn and age interacted with many of the relationships between first aid and outcome and these are described and discussed.
Discussion & Conclusion: This study suggests that there are significant patient and health system benefits from cooling water first aid, particularly if applied for up to 20 minutes. The results of this study estimate the effect size of post-burn first aid and confirm that efforts to promote first aid knowledge are not only warranted, but provide potential cost savings
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