3,624 research outputs found
The form factors from analyticity and unitarity
We study the shape parameters of the scalar and vector form factors
using as input dispersion relations and unitarity for the moments of suitable
heavy-light correlators evaluated with Operator Product Expansions, including
terms in perturbative QCD. For the scalar form factor, a low
energy theorem and phase information on the unitarity cut are implemented to
further constrain the shape parameters. We finally determine points on the real
axis and isolate regions in the complex energy plane where zeros of the form
factors are excluded.Comment: 6 pages, 4 figures; Seminar given at DAE-BRNS Workshop on Hadron
Physics Bhabha Atomic Research Centre, Mumbai, India, October 31-November 4,
2011, submitted to Proceeding
Dalitz plot slope parameters for decays and two particle interference
We study the possible distortion of phase-space in the decays , which may result from final state interference among the decay products.
Such distortion may influence the values of slope parameters extracted from the
Dalitz plot distribution of these decays. We comment on the consequences on the
magnitude of violation of the rule in these decays.Comment: 17 pages, LaTex2e, 6 figures, v2 authors' affiliation modified, to
appear in Mod. Phys. Lett.
Lorentz Multiplet Structure of Baryon Spectra and Relativistic Description
The pole positions of the various baryon resonances are known to reveal
well-pronounced clustering, so-called Hoehler clusters. For nonstrange baryons
the Hoehler clusters are shown to be identical to Lorentz multiplets of the
type (j,j)*[(1/2,0)+(0,1/2)] with j being a half-integer. For the Lambda
hyperons below 1800 MeV these clusters are shown to be of the type [(1,0)+
(0,1)]*[(1/2,0)+(0,1/2)] while above 1800 MeV they are parity duplicated
(J,0)+(0,J) (Weinberg-Ahluwalia) states. Therefore, for Lambda hyperons the
restoration of chiral symmetry takes place above 1800 MeV. Finally, it is
demonstrated that the description of spin-3/2 particles in terms of a 2nd rank
antisymmetric Lorentz tensor with Dirac spinor components does not contain any
off-shell parameters and avoids the main difficulties of the Rarita-Schwinger
description based upon a 4-vector with Dirac spinor components.Comment: 12 pages, LaTex, submitted to Mod. Phys. Lett.
Jets associated with Z^0 boson production in heavy-ion collisions at the LHC
The heavy ion program at the LHC will present unprecedented opportunities to
probe hot QCD matter, that is, the quark gluon plasma (QGP). Among these
exciting new probes are high energy partons associated with the production of a
Z^0 boson, or Z^0 tagged jets. Once produced, Z^0 bosons are essentially
unaffected by the strongly interacting medium produced in heavy-ion collisions,
and therefore provide a powerful signal of the initial partonic energy and
subsequent medium induced partonic energy loss. When compared with theory,
experimental measurements of Z^0 tagged jets will help quantify the jet
quenching properties of the QGP and discriminate between different partonic
energy loss formalisms. In what follows, I discuss the advantages of tagged
jets over leading particles, and present preliminary results of the production
and suppression of Z^0 tagged jets in relativistic heavy-ion collisions at LHC
energies using the Guylassy-Levai-Vitev (GLV) partonic energy loss formalism.Comment: To appear in the proceedings of the 2010 Winter Workshop on Nuclear
Dynamics, which was held in Ocho Rios, Jamaica, mon
decays revisited: branching ratios and T-odd momenta correlations
We calculate the branching ratios of the decays, and the T-odd triple momenta correlations
, due to the
electromagnetic final state interaction, in these processes. The contributions
on the order of and to the corresponding amplitudes
are treated exactly. For the branching ratios, the corrections on the order of
are estimated and demonstrated to be small. We compare the results
with those of other authors. In some cases our results differ considerably from
the previous ones.Comment: 13 pages, 11 figures; references adde
Symmetries, Large Leptonic Mixing and a Fourth Generation
We show that large leptonic mixing occurs most naturally in the framework of
the Sandard Model just by adding a fourth generation. One can then construct a
small discrete symmetry, instead of the large ,
which requires that the neutrino as well as the charged lepton mass matrices be
proportional to a democratic mass matrix, where all entries are
equal to unity. Without considering the see-saw mechanism, or other more
elaborate extensions of the SM, and contrary to the case with only 3
generations, large leptonic mixing is obtained when the symmetry is broken.Comment: 6 pages, ReVTeX, no figure
Minimal Length Uncertainty Relation and Hydrogen Atom
We propose a new approach to calculate perturbatively the effects of a
particular deformed Heisenberg algebra on energy spectrum. We use this method
to calculate the harmonic oscillator spectrum and find that corrections are in
agreement with a previous calculation. Then, we apply this approach to obtain
the hydrogen atom spectrum and we find that splittings of degenerate energy
levels appear. Comparison with experimental data yields an interesting upper
bound for the deformation parameter of the Heisenberg algebra.Comment: 7 pages, REVTe
New England Regional Health Equity Profile & Call to Action
Good health is a foundation that allows people to participate in the most important aspects of life. The purpose of the New England Regional Health Equity Profile and Call to Action is to identify where differences in good health exist among racial, ethnic, and disability populations in New England as well as foster policy, programmatic, and individual action to combat health disparities and achieve health equity for racial, ethnic, disability and underserved populations in New England. The report was written by the members of the New England Regional Health Equity Council (RHEC), one of ten regional health equity councils formed by the Office of Minority Health at the federal Department of Health and Human Services. The mission of the New England RHEC is to achieve health equity for all through collective action in the New England region. The New England RHEC’s vision is to achieve health equity through cross-sector interaction and collaboration of activities and resources to optimize health for all where they live, learn, work, and play.
The New England Regional Health Equity Profile and Call to Action uses a “social determinants of health” approach. A social determinants of health approach focuses on understanding how the intersection of the social and physical environments; individual behaviors; and access to education, income, healthy foods and health care, impacts a wide range of health and quality-of-life outcomes. The report examines the following topics: Socio-Economic Status, Healthy Eating and Physical Activity, Risky Behaviors, Cultural Competency in Health Care, Health Care Access, Health Outcomes, and the Intersection of Race/Ethnicity & Disability. It also includes a description of State Health Equity Activities and a Regional Call to Action
Upper Bound on the Mass of the Type III Seesaw Triplet in an SU(5) Model
We investigate correlation between gauge coupling unification, fermion mass
spectrum, proton decay, perturbativity and ultraviolet cutoff within an SU(5)
grand unified theory with minimal scalar content and an extra adjoint
representation of fermions. We find strong correlation between the upper bound
on the mass of both the bosonic and fermionic SU(2) triplets and the cutoff.
The upper bound on the mass of fermionic triplet responsible for Type III
seesaw mechanism is 10^{2.1} GeV for the Planck scale cutoff. In that case both
the idea of grand unification and nature of seesaw mechanism could be tested at
future collider experiments through the production of those particles.
Moreover, the prediction for the proton decay lifetime is at most an order of
magnitude away from the present experimental limits. If the cutoff is lowered
these predictions change significantly. In the most general scenario, if one
does (not) neglect a freedom in the quark and lepton mixing angles, the upper
bound on the fermionic triplet mass is at 10^{5.4} GeV (10^{10} GeV). Since the
predictions of the model critically depend on the presence of the
higher-dimensional operators and corresponding cutoff we address the issue of
their possible origin and also propose alternative scenarios that implement the
hybrid seesaw framework of the original proposal.Comment: 13 pages, 2 figures, minor changes introduced to match the JHEP
versio
Effects of Vibration Located on the Steel Truss Bridges Under Moving Load
Structural vibration control as an advanced technology in engineering consists of implementing energy dissipation devices or control systems into structures to reduce excessive structural vibration, enhance human comfort and prevent catastrophic structural failure due to strong winds and earthquakes, among other inputs. When the bridge carries heavy traffic, vibrations in the bridge structural elements subjected to high levels of stress. This tension bridge subjected to fatigue. This paper studies and focus the effects of vibration of steel truss bridges and finally to suggest future directions of research and innovation. The possibilities of modal properties of global and local vibration method in determining the structural changes in the truss bridges discussed located to the results of finite element analysis
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