27,348 research outputs found
Heavy Meson Masses in the \epsilon-Regime of HM\chi PT
The pseudoscalar and vector heavy meson masses are calculated in the
\epsilon-regime of Heavy Meson Chiral Perturbation Theory to order \epsilon^4.
The results of this calculation will allow the determination of low-energy
coefficients (LECs) directly from Lattice QCD calculations of the heavy mesons
masses for lattices that satisfy the \epsilon-regime criteria. In particular,
the LECs that parametrize the NLO volume dependance of the heavy meson masses
are necessary for evaluating the light pseudoscalar meson (\pi, K, \eta) and
heavy meson ({D^0, D^+, D^+_s}, {B^-,\bar{B}^0,\bar{B}^0_s}) scattering phase
shifts.Comment: 16 pages, 6 figure
Mathematics from China to Virginia by Way of Singapore
Our article follows from an interesting concurrence of mathematical and educational lines. At least the concurrence seems so to us and we hope that those who read on will agree. The lines or streams are a joint minimester program at St. Catherine’s and St. Christopher‘s Schools, an interest in problem solving, and a Singapore connection. We shall describe the lines first and then describe the mathematics that we found at their intersection
Shortcuts to Thermodynamic Computing: The Cost of Fast and Faithful Erasure
Landauer's Principle states that the energy cost of information processing
must exceed the product of the temperature and the change in Shannon entropy of
the information-bearing degrees of freedom. However, this lower bound is
achievable only for quasistatic, near-equilibrium computations -- that is, only
over infinite time. In practice, information processing takes place in finite
time, resulting in dissipation and potentially unreliable logical outcomes. For
overdamped Langevin dynamics, we show that counterdiabatic potentials can be
crafted to guide systems rapidly and accurately along desired computational
paths, providing shortcuts that allows for the precise design of finite-time
computations. Such shortcuts require additional work, beyond Landauer's bound,
that is irretrievably dissipated into the environment. We show that this
dissipated work is proportional to the computation rate as well as the square
of the information-storing system's length scale. As a paradigmatic example, we
design shortcuts to erase a bit of information metastably stored in a
double-well potential. Though dissipated work generally increases with erasure
fidelity, we show that it is possible perform perfect erasure in finite time
with finite work. We also show that the robustness of information storage
affects the energetic cost of erasure---specifically, the dissipated work
scales as the information lifetime of the bistable system. Our analysis exposes
a rich and nuanced relationship between work, speed, size of the
information-bearing degrees of freedom, storage robustness, and the difference
between initial and final informational statistics.Comment: 19 pages, 7 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/scte.ht
Raman gain against a background of non-thermal ion fluctuations in a plasma
A complex stimulated Raman scattering event against a background of non-thermal ion acoustic waves in an inhomogeneous plasma is described. We obtain analytic forms for the Raman gain due to a five-wave interaction consisting of conventional three-wave Raman scattering followed by the decay of the Raman Langmuir wave into a second Langmuir wave (or a second scattered light wave) and an ion acoustic wave. Very modest levels of ion waves produce a. significant effect on Raman convective gain. A combination of plasma inhomogeneity and suprathermal ion fluctuations may offer a means for the control of Raman gain
Summer Camp as a Force for 21st Century Learning: Exploring Divergent Thinking and Activity Selection in a Residential Camp Setting
This study investigated change in divergent thinking (DT), an indicator of creative potential, at two gender-specific residential summer camps. Additionally, this study examined whether the change in DT varied by gender and by the type of activities campers self-select. Quantitative methods, using a quasi-experimental design was used in order to understand differences in camper scores. A total of 189 youth, 100 girls, 89 boys, between the ages of 9 and 14 years participated in the current study. Participants were administered a modified version of Guilford\u27s (1967) alternate uses task, a measure of DT, in which respondents were asked questions such as name all of the uses for a brick or name all of the uses for a plate before the camp session started, and then again at the end of the two-week session. Results indicate overall mean significant increases in DT across all scoring methods of fluency, flexibility, and originality. Participants who self-selected one or more artistic activities (e.g., drama, arts and crafts, dance) had significant increases on the tasks as opposed to participants who did not select any artistic activities (e.g., basketball, baseball, archery). Finally, girls significantly increased across all scoring methods, whereas boys slightly increased in fluency and flexibility but not in originality. These results indicate residential summer camp may provide a creativity benefit for youth in attendance, especially those who participate in certain activities. Practitioners should use this study to understand their own programming in terms of creativity, activity offerings, and camp cultur
Bounds on Heavy-to-Heavy Mesonic Form Factors
We provide upper and lower bounds on the form factors for B -> D, D^* by
utilizing inclusive heavy quark effective theory sum rules. These bounds are
calculated to leading order in Lambda_QCD/m_Q and alpha_s. The O(alpha_s^2
beta_0) corrections to the bounds at zero recoil are also presented. We compare
our bounds with some of the form factor models used in the literature. All the
models we investigated failed to fall within the bounds for the combination of
form factors (omega^2 - 1)/(4 omega)|omega h_{A2}+h_{A3}|^2.Comment: 27 pages, 10 figure
Two-peaked and flat-top perfect bright solitons in epsilon-near-zero nonlinear metamaterials: novel Kerr self-trapping mechanisms
We analytically investigate transverse magnetic (TM) spatial bright solitons,
as exact solutions of Maxwell's equations, propagating through nonlinear
metamaterials whose linear dielectric permittivity is very close to zero and
whose effective nonlinear Kerr parameters can be tailored to achieve values not
available in standard materials. Exploiting the fact that, in the considered
medium, linear and nonlinear polarization can be comparable at feasible and
realistic optical intensities, we identify two novel self-trapping mechanisms
able to support two-peaked and flat-top solitons, respectively. Specifically,
these two novel mechanisms are based on the occurrence of critical points at
which the effective nonlinear permittivity vanishes, the two mechanisms
differing in the way the compensation between linear and nonlinear polarization
is achieved through the non-standard values of the nonlinear parameters.Comment: 7 pages, 4 figure
PAH in the laboratory and interstellar space
The theory that polycyclic aromatic hydrocarbons (PAHs) are a constituent of the interstellar medium, and a source of the IR emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 microns is being studied using PAH containing acid insoluble residue of the Orgueil CI meteorite and coal tar. FTIR spectra of Orgueil PAH material that has undergone thermal treatment, and a solvent insoluble fraction of coal tar that has been exposed to hydrogen plasma are presented. The UV excided luminescence spectrum of a solvent soluble coal tar film is also shown. Comparison of the lab measurements with observations appears to support the interstellar PAH theory, and shows the process of dehydrogenation expected to take place in the interstellar medium
Polarization squeezing of light by single passage through an atomic vapor
We have studied relative-intensity fluctuations for a variable set of
orthogonal elliptic polarization components of a linearly polarized laser beam
traversing a resonant Rb vapor cell. Significant polarization squeezing
at the threshold level (-3dB) required for the implementation of several
continuous variables quantum protocols was observed. The extreme simplicity of
the setup, based on standard polarization components, makes it particularly
convenient for quantum information applications.Comment: Revised version. Minor changes. four pages, three figure
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