Decay Constants of Pseudoscalar Mesons to Two Loops in Three-Flavor Partially Quenched χ\chiPT

This paper presents a first study of the decay constants of the charged, or flavor-off-diagonal, pseudoscalar mesons to two loops for three flavors of sea quarks, in Partially Quenched Chiral Perturbation Theory (PQ$\chi$PT). Explicit analytical expressions up to ${\cal O}(p^6)$ in the momentum expansion are given. The calculations have been performed within the supersymmetric formulation of PQ$\chi$PT. We also present some numerical results to indicate the size of the corrections.Comment: 14

Partially Quenched and Three Flavour ChPT at Two Loops

A summary of recent progress in Chiral Perturbation Theory (ChPT) at the two-loop level is given. A short introduction to ChPT is included, along with an explanation of the usefulness of developing ChPT for partially quenched QCD. Further, our recent work in partially quenched ChPT is reviewed, and a few comments are given on older work in mesonic ChPT at the two-loop level. In particular, we quote the present best values for the low-energy constants of the $\mathcal{O}(p^4)$ chiral Lagrangian.Comment: 11 pages, invited talk at ``Final Euridice Meeting'', August 24-28 2006, Kazimierz, Polan

Partially Quenched Chiral Perturbation Theory to NNLO

This paper summarizes the recent calculations of the masses and decay constants of the pseudoscalar mesons at the two-loop level, or NNLO, in Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications include chiral extrapolations of Lattice QCD, as well as the determination of the low-energy constants (LEC:s) of QCD.Comment: To appear in the proceedings of PANIC 200

Experimental Studies of the Effective Width of Buckled Sheets

The object of the present experiments is a more exact determination of the effective width for the case of pure compression and of the sheet clamped at the angle section. From the experimental data of the effective width the calculation of the buckling load of an angle joined to a thin sheet is then deduced. The test material consisted of spring-hardened brass sheet

Tests for the determination of the stress condition in tension fields

The present experiments treat the stress of actual tension fields within the elastic range. They give the magnitude of the flexural stresses due to wrinkling. They also disclose, particularly by slightly exceeded buckling load, the marked unloading - as compared with the tension-field theory - of the uprights as a result of the flexural stiffness of the web plate. The test sheets were clamped at the edges and brought to buckling through shearing and compressive stresses applied in the direction of the long sides

Brake Wear Particle Emissions of a Passenger Car Measured on a Chassis Dynamometer

Brake wear emissions with a special focus on particle number (PN) concentrations were investigated during a chassis dynamometer measurement campaign. A recently developed, well-characterized, measurement approach was applied to measure brake particles in a semi-closed vehicle setup. Implementation of multiple particle measurement devices allowed for simultaneous measurement of volatile and solid particles. Estimated PN emission factors for volatile and solid particles differed by up to three orders of magnitude with an estimated average solid particle emission factor of 3∙109 # km−1 brake−1 over a representative on-road brake cycle. Unrealistic high brake temperatures may occur and need to be ruled out by comparison with on-road temperature measurements. PN emissions are strongly temperature dependent and this may lead to its overestimation. A high variability for PN emissions was found when volatile particles were not removed. Volatiles were observed under high temperature conditions only which are not representative of normal driving conditions. The coefficient of variation for PN emissions was 1.3 without catalytic stripper and 0.11 with catalytic stripper. Investigation of non-braking sections confirmed that particles may be generated at the brake even if no brakes are applied. These "off-brake-event" emissions contribute up to about 30% to the total brake PM10 emission

Model-independent Study of Magnetic Dipole Transitions in Quarkonium

We study magnetic dipole (M1) transitions between two quarkonia in the framework of non-relativistic effective field theories of QCD. Relativistic corrections of relative order v^2 are investigated in a systematic fashion. Non-perturbative corrections due to color-octet effects are considered for the first time and shown to vanish at leading order. Exact, all order expressions for the relevant 1/m and 1/m^2 operators are derived. The results allow us to scrutinize several potential model claims. In particular, we show that QCD excludes both contributions to the anomalous magnetic moment of the quarkonium induced by low-energy fluctuations and contributions to the magnetic dipole operators of the type induced by a scalar potential. Finally, we apply our results to the transitions J/psi -> eta_c gamma, Upsilon(1S) -> eta_b gamma, Upsilon(2S) -> eta_b(2S) gamma, Upsilon(2S) -> eta_b gamma, eta_b(2S) -> Upsilon(1S) gamma, h_b(1P) -> chi_{b0,1}(1P) gamma and chi_{b2}(1P) -> h_b(1P) gamma by assuming these quarkonium states in the weak-coupling regime. Our analysis shows that the J/psi -> eta_c gamma width is consistent with a weak-coupling treatment of the charmonium ground state, while such a treatment for the hindered transition Upsilon(2S) -> eta_b gamma appears difficult to accommodate within the CLEO III upper limit.Comment: 44 pages, 8 figures; typos corrected, one reference added; to appear in Physical Review