2,562 research outputs found
Semileptonic decays of meson to S-wave charmonium states in the perturbative QCD approach
Inspired by the recent measurement of the ratio of branching fractions
to and final states at the LHCb
detector, we study the semileptonic decays of meson to the S-wave ground
and radially excited 2S and 3S charmonium states with the perturbative QCD
approach. After evaluating the form factors for the transitions , where and denote pseudoscalar and vector S-wave charmonia,
respectively, we calculate the branching ratios for all these semileptonic
decays. The theoretical uncertainty of hadronic input parameters are reduced by
utilizing the light-cone wave function for meson. It is found that the
predicted branching ratios range from up to and could be
measured by the future LHCb experiment. Our prediction for the ratio of
branching fractions is in good
agreement with the data. For decays, the relative
contributions of the longitudinal and transverse polarization are discussed in
different momentum transfer squared regions. These predictions will be tested
on the ongoing and forthcoming experiments.Comment: 12 pages, 3 figures, 5 table
Negative Binomial States of the Radiation Field and their Excitations are Nonlinear Coherent States
We show that the well-known negative binomial states of the radiation field
and their excitations are nonlinear coherent states. Excited nonlinear coherent
state are still nonlinear coherent states with different nonlinear functions.
We finally give exponential form of the nonlinear coherent states and remark
that the binomial states are not nonlinear coherent states.Comment: 10 pages, no figure
Chemical heat storage for saving the exhaust gas energy in a spark ignition engine
This study was aimed to develop a chemical heat storage system using magnesium hydroxide (Mg(OH)2) and its dehydration and hydration reactions to recover the energy wasted in internal combustion engines (IC engine). The thermal energy of exhaust gas will be stored in the dehydration of Mg(OH)2 to become MgO and H2O, and to release in the hydration of MgO. Experiments were conducted on a 6-cylinder spark ignition engine to estimate the amount of energy loss in the exhaust gas and the reactor efficiency in the dehydration process. The stored heat used to heat fresh air from the ambient temperature to more convenient temperature. Results of the preliminary investigation show that the proposed chemical heat storage system is feasible to recover approximately 5.8 % of the heat loss and the temperature of the air is from 275.5 K to 305.4 K (with the ambient temperature is from 253 K to 283 K and the water vapor pressure is 47kPa)
3-(4-Carboxy-5-carboxylato-1H-imidazol-2-yl)pyridin-1-ium monohydrate
In the zwitterionic molecule of the title compound, C10H7N3O4·H2O, one carboxyl group is deprotonated and the pyridine N atom is protonated. The pyridinium and imidazole rings form a dihedral angle of 5.23 (1)°. An intramolecular O—H⋯O hydrogen bond occurs. In the crystal, intermolecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the zwitterions and water molecules into sheets parallel to (102)
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