1,672 research outputs found
Mechanochemical enzymes and protein machines as hydrodynamic force dipoles: The active dimer model
Mechanochemically active enzymes change their shapes within every turnover cycle. Therefore, they induce circulating flows in the solvent around them and behave as oscillating hydrodynamic force dipoles. Because of non-equilibrium fluctuating flows collectively generated by the enzymes, mixing in the solution and diffusion of passive particles within it are expected to get enhanced. Here, we investigate the intensity and statistical properties of such force dipoles in the minimal active dimer model of a mechanochemical enzyme. In the framework of this model, novel estimates for hydrodynamic collective effects in solution and in lipid bilayers under rapid rotational diffusion are derived, and available experimental and computational data is examined
Developing Cloud Chambers with High School Students
The result and outcome of the \textit{cloud chamber project}, which aims to
develop a cloud chamber useful for science education is reported in detail. A
project includes both three high school students and a teacher as a part of
Super Science High School (SSH) program in our school. We develop a
dry-ice-free cloud chamber using salt and ice (or snow). Technical details of
the chamber are described. We also argue how the project have affected
student's cognition, motivation, academic skills and behavior. The research
project has taken steps of professional researchers, i.e., in planning
research, applying fund, writing a paper and giving a talk in conferences. From
interviews with students, we have learnt that such style of scientific activity
is very effective in promoting student's motivation for learning science.Comment: 9 pages, accepted to the proceedings of APPC12 - the 12th Asia
Pacific Physics Conferenc
Production of the pentaquark in scattering
We study and processes
for both of the positive and negative parities of the . Employing
the effective chiral Lagrangians for the and interactions, we
calculate differential cross sections as well as total cross sections for the
and reactions. The total
cross sections for the positive-parity turn out to be approximately
ten times larger than those for the negative parity in the range of
the CM energy . The results are
rather sensitive to the mechanism of exchanges in the -- channel.Comment: 9 pages and 11 figure
Exotic Tetraquark ud bar[s] bar[s] of J^P=0^+ in the QCD Sum Rule
We study a QCD sum rule analysis for an exotic tetraquark ud bar[s] bar[s] of
J^P=0^+ and I = 1. We construct q q bar[q] bar[q] currents in a local product
form and find that there are five independent currents for this channel. Due to
high dimensional nature of the current, it is not easy to form a good sum rule
when using a single current. This means that we do not find any sum rule window
to extract reliable results, due to the insufficient convergence of the OPE and
to the exceptional important role of QCD continuum. Then we examine sum rules
by using currents of linear combinations of two currents among the independent
ones. We find two reasonable cases that predict a mass of the tetraquark around
1.5 GeV.Comment: 15 pages, 8 figures, revised versio
Baryons with U_L(3)*U_R(3) Chiral Symmetry IV: Interactions with Chiral (8,1)+(1,8) Vector and Axial-vector Mesons and Anomalous Magnetic Moments
We construct all SU_L(3)*SU_R(3) chirally invariant anomalous magnetic, i.e.
involving a Pauli tensor and one-derivative, interactions of one
chiral-[(8,1)+(1,8)] meson field with chiral-[(6,3)+(3,6)],
[(3,\bar3)+(\bar3,3)], and [(8,1)+(1,8)] baryon fields and their "mirror"
images. We find strong chiral selection rules: e.g. there is only one
off-diagonal chirally symmetric anomalous magnetic interaction between J=1/2
fields belonging to the [(6,3)+(3,6)] and the [(3,\bar3)+(\bar3,3)] chiral
multiplets. We also study the chiral selection rules for the anomalous magnetic
interactions of the [(3,\bar3)+(\bar3,3)] and the [(8,1)+(1,8)] baryon fields.
Again, no diagonal and only one off-diagonal chiral SU_L(3)*SU_R(3) interaction
of this type is allowed, that turns out also to conserve the U_A(1) symmetry.
We calculate the F/D ratios for the baryons' anomalous magnetic moments
predicted by these interactions in the SU(3) symmetry limit and find that only
the [(6,3)+(3,6)]-[(3,\bar3)+(\bar3,3)] one, reproduces F/D=1/3, in close
proximity to the value extracted from experiment.Comment: 16 pages, 2 tables, accepted by PR
Exotic mesons with hidden charm and bottom near thresholds
We study heavy hadron spectroscopy near heavy meson thresholds. We employ
heavy pseudoscalar meson P and heavy vector meson P* as effective degrees of
freedom and consider meson exchange potentials between them. All possible
composite states which can be constructed from the P and P* mesons are studied
up to the total angular momentum J <= 2. We consider, as exotic states,
isosinglet states with exotic J^{PC} quantum numbers and isotriplet states. We
solve numerically the Schr\"odinger equation with channel-couplings for each
state. We found B(*)barB(*) molecule states for I^G(J^{PC}) = 1^+(1^{+-})
correspond to the masses of twin resonances Zb(10610) and Zb(10650). We predict
several possible B(*)barB(*) bound and/or resonant states in other channels. On
the other hand, there are no B(*)barB(*) bound and/or resonant states whose
quantum numbers are exotic.Comment: 10 pages, 1 figure, to appear in the proceedings of The 5th
International Workshop on Charm Physics (Charm 2012
Chiral symmetry breaking and stability of strangelets
We discuss the stability of strangelets by considering dynamical chiral
symmetry breaking and confinement. We use a
symmetric Nambu--Jona-Lasinio model for chiral symmetry breaking supplemented
by a boundary condition for confinement. It is shown that strangelets with
baryon number can stably exist. For the observables, we
obtain the masses and the charge-to-baryon number ratios of the strangelets.
These quantities are compared with the observed data of the exotic particles.Comment: 10 pages, 9 figures, submitted to Physical Review
Exotic baryons from a heavy meson and a nucleon
We evaluate a hadronic molecule formed by a heavy meson and a nucleon
respecting heavy quark symmetry. The tensor force of pion exchange potential
plays a dominate role to produce an strong attraction in this system. Solving
coupled channel Schr\"odinger equations for PN and P* N, we find many bound and
resonant states with isospin I=0 while there are few resonances in I=1 state.
The rich structures with I=0 indicate that the spectrum of heavy baryons near
the threshold is influenced by the contributions from such hadron composite
structures.Comment: To appear in the proceedings of The 5th International Workshop on
Charm Physics (Charm 2012
- …