10,704 research outputs found
Anisotropic Relaxation Functions and Strength of Oriented Solids Technical Report No. 106
Anisotropic relaxation functions and strength of oriented solid
Aerodynamic properties of turbulent combustion fields
Flow fields involving turbulent flames in premixed gases under a variety of conditions are modeled by the use of a numerical technique based on the random vortex method to solve the Navier-Stokes equations and a flame propagation algorithm to trace the motion of the front and implement the Huygens principle, both due to Chorin. A successive over-relaxation hybrid method is applied to solve the Euler equation for flows in an arbitrarily shaped domain. The method of images, conformal transformation, and the integral-equation technique are also used to treat flows in special cases, according to their particular requirements. Salient features of turbulent flame propagation in premixed gases are interpreted by relating them to the aerodynamic properties of the flow field. Included among them is the well-known cellular structure of flames stabilized by bluff bodies, as well as the formation of the characteristic tulip shape of flames propagating in ducts. In its rudimentary form, the mechanism of propagation of a turbulent flame is shown to consist of: (1) rotary motion of eddies at the flame front, (2) self-advancement of the front at an appropriate normal burning speed, and (3) dynamic effects of expansion due to exothermicity of the combustion reaction. An idealized model is used to illustrate these fundamental mechanisms and to investigate basic aerodynamic features of flames in premixed gases. The case of a confined flame stabilized behind a rearward-facing step is given particular care and attention. Solutions are shown to be in satisfactory agreement with experimental results, especially with respect to global properties such as the average velocity profiles and reattachment length
Search for states in decays at the LHCb
We consider and as the vector tetraquark states of
and , respectively. By
connecting to , we predict that
the branching ratios of
and are and , which are accessible to the
experiments at the LHCb, respectively. The measurements of these
modes would be the first experimental evidences for the states in
baryonic decays.Comment: 7 pages, 1 figure
Pentaquarks from intrinsic charms in decays
We study the three-body decays of with
and . The two new states and observed recently as
the resonances in the invariant mass spectrum of can be identified to consist of five quarks, , being
consistent with the existence of the pentaquark states. We argue that, in the
doubly charmful decays of through , apart from those through the non-resonant and
resonant transitions, the third contribution
with the non-factorizable effects is not the dominant part for the resonant
processes,
such that we propose that the productions are mainly from
the charmless decays through , in which the content in arises from the intrinsic charms within the
baryon. We hence predict the observables related to the branching
ratios and the direct CP violating asymmetries to be , , and , which can alleviate the
inconsistency between the theoretical expectations from the three contributions
in the doubly charmful decays and the observed data.Comment: 10 pages, 2 figures, revised version accepted by PL
Radiative Baryonic Decays
We study the structure-dependent contributions to the radiative baryonic
decays of in the standard model. We show
that the decay branching ratios of are
, which are larger than the estimated values of
induced from inner bremsstrahlung effects of the corresponding two-body modes.
In particular, we find that is around , which is close to the pole model estimation but smaller than
the experimental measurement from BELLE.Comment: 11 pages, 2 figures, Revtex4, new fitting is include
Identifying Glueball at 3.02 GeV in Baryonic Decays
We examine the nature of the unknown enhancement around 3 GeV observed by the
BABAR collaboration in the spectrum of the decay. Suspecting that the peak is a resonance, which can be neither
identified as a charmonium state, such as or , nor classified
as one of the light-flavor mesons, we conclude that it corresponds to a
glueball fitted as X(3020) with , which could be the first glueball state above 3 GeV. This
state also appears in the spectrum of the decay.Comment: 11 pages, 2 figure, title changed, revised version accepted by PL
Determinations of and from baryonic decays
We extract the Cabibbo-Kobayashi-Maskawa matrix element from the
exclusive decays of and with and , where the
branching ratios of measured with high
precisions have not been used in the previous studies. Explicitly, we find
, which agrees with the value of
from the inclusive
decays. Furthermore, based on the most recent ratio of from
the exclusive decays, we obtain , which is close to the value of from
the inclusive decays. We conclude that our
determinations of and from the exclusive
decays favor the inclusive extractions in the decays.Comment: 8 pages, i figur
Four-body baryonic decays of and
We study the four-body baryonic decays with
() being charmless baryons (mesons). In accordance with
the recent LHCb observations, each decay is considered to proceed through the
transition together with the production of a baryon pair. We
obtain that and , in agreement with the data. We
also predict , which is accessible to the LHCb and BELLE experiments.Comment: 11 pages, 3 figure
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