A look inside charmed-strange baryons from lattice QCD

The electromagnetic form factors of the spin-3/2 $\Omega$ baryons, namely $\Omega$, $\Omega_c^\ast$, $\Omega_{cc}^\ast$ and $\Omega_{ccc}$, are calculated in full QCD on $32^3\times 64$ PACS-CS lattices with a pion mass of 156(9) MeV. The electric charge radii and magnetic moments from the $E0$ and $M1$ multipole form factors are extracted. Results for the electric quadrupole form factors, $E2$, are also given. Quark sector contributions are computed individually for each observable and then combined to obtain the baryon properties. We find that the charm quark contributions are systematically smaller than the strange-quark contributions in the case of the charge radii and magnetic moments. $E2$ moments of the $\Omega_{cc}^\ast$ and $\Omega_{ccc}$ provide a statistically significant data to conclude that their electric charge distributions are deformed to an oblate shape. Properties of the spin-1/2 $\Omega_c$ and $\Omega_{cc}$ baryons are also computed and a thorough comparison is given. This complete study gives valuable hints about the heavy-quark dynamics in charmed hadrons.Comment: 14 pages, 14 figures. Includes a subsection on the systematic effect

Electromagnetic structure of charmed baryons in Lattice QCD

As a continuation of our recent work on the electromagnetic properties of the doubly charmed $\Xi_{cc}$ baryon, we compute the charge radii and the magnetic moments of the singly charmed $\Sigma_c$, $\Omega_c$ and the doubly charmed $\Omega_{cc}$ baryons in 2+1 flavor Lattice QCD. In general, the charmed baryons are found to be compact as compared to the proton. The charm quark acts to decrease the size of the baryons to smaller values. We discuss the mechanism behind the dependence of the charge radii on the light valence- and sea-quark masses. The magnetic moments are found to be almost stable with respect to changing quark mass. We investigate the individual quark sector contributions to the charge radii and the magnetic moments. The magnetic moments of the singly charmed baryons are found to be dominantly determined by the light quark and the role of the charm quark is significantly enhanced for the doubly charmed baryons.Comment: Updated results, improved analysis. Version to appear in JHE

Electromagnetic properties of doubly charmed baryons in Lattice QCD

We compute the electromagnetic properties of \Xi_cc baryons in 2+1 flavor Lattice QCD. By measuring the electric charge and magnetic form factors of \Xi_cc baryons, we extract the magnetic moments, charge and magnetic radii as well as the \Xi_cc \Xi_cc \rho coupling constant, which provide important information to understand the size, shape and couplings of the doubly charmed baryons. We find that the two heavy charm quarks drive the charge radii and the magnetic moment of \Xi_cc to smaller values as compared to those of, e.g., the proton.Comment: 15 pages, 5 figures; added discussions and references, version accepted by PL

LHC Charge Asymmetry as Constraint on Models for the Tevatron Top Anomaly

The forward-backward asymmetry $A_{FB}^{t\bar t}$ in top quark production at the Tevatron has been observed to be anomalously large by both CDF and D0. It has been suggested that a model with a $W'$ coupling to $td$ and $ub$ might explain this anomaly, and other anomalies in $B$ mesons. Single-top-quark production in this model is large, and arguably in conflict with Tevatron measurements. However the model might still be viable if $A_{FB}^{t\bar t}$ is somewhat smaller than its current measured central value. We show that even with smaller couplings, the model can be discovered (or strongly excluded) at the LHC using the 2010 data sets. We find that a suitable charge-asymmetry measurement is a powerful tool that can be used to constrain this and other sources of anomalous single-top production, and perhaps other new high-energy charge-asymmetric processes.Comment: 25 pages, 4 figures, note adde

Vector and axial-vector couplings of D and D* mesons in 2+1 flavor Lattice QCD

Using the axial-vector coupling and the electromagnetic form factors of the D and D* mesons in 2+1 flavor Lattice QCD, we compute the D*D\pi, DD\rho and D*D*\rho coupling constants, which play an important role in describing the charm hadron interactions in terms of meson-exchange models. We also extract the charge radii of D and D* mesons and determine the contributions of the light and charm quarks separately.Comment: 19 pages, 3 figures; added references and comments, published versio

Robust Entanglement in Atomic Systems via Lambda-Type Processes

It is shown that the system of two three-level atoms in $\Lambda$ configuration in a cavity can evolve to a long-lived maximum entangled state if the Stokes photons vanish from the cavity by means of either leakage or damping. The difference in evolution picture corresponding to the general model and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure

A micro-perfusion chamber for single-cell fluorescence measurements

Abstract A versatile closed micro-perfusion chamber designed for single-cell fluorescence measurements under maximum microscopic magnification is described. Glass coverslips with adherent cells can be attached to the top or bottom of the chamber, depending on whether an inverted or an upright microscope is used. Eight conical holes drilled in the side of the chamber serve for the insertion of plugs with attachments for perfusion, rapid injection of small amounts of reagents, temperature measurements or for heating the interior of the chamber. Materials used in the construction of the chamber are non-toxic and resistant to standard sterilization procedures. Perfusion and temperature properties of the chamber are described. Single cell fluorescence measurements are presented in human monocyte-derived macrophages in which NAD(P)H and intracellular calcium are measured