The quenched generating functional for hadronic weak interactions

The ultraviolet behaviour of the generating functional for hadronic weak interactions with $|\Delta S| =1, 2$ is investigated to one loop for a generic number of flavours and in the quenched approximation. New quenched chiral logarithms generated by the weak interactions can be accounted for via a redefinition of the weak mass term in the $\Delta S=\pm 1$ weak effective Lagrangian at leading order. Finally, we illustrate how chiral logarithms are modified by the quenched approximation in $K\to\pi\pi$ matrix elements with $\Delta I=1/2$ and 3/2.Comment: LATTICE98(matrixelement), 3 page

Quenched chiral perturbation theory to one loop

We calculate the divergences of the generating functional of quenched chiral perturbation theory at one loop, and renormalize the theory by an appropriate definition of the counterterms. We show that the quenched chiral logarithms can be accounted for by defining a renormalized B0 parameter which, at lowest order, is proportional to the vacuum expectation value of the scalar quark density. Finally, we calculate several quantities at one loop to better analyze the modifications induced by quenching in the ultraviolet finite part of the one-loop corrections. We point out that some of the finite loop corrections may diverge in the chiral limit.

Holography, Heavy-Quark Free Energy, and the QCD Phase Diagram

We use gauge/string duality to investigate the free energy of two static color sources (a heavy quark-antiquark pair) in a Yang-Mills theory in strongly interacting matter, varying temperature and chemical potential. The dual space geometry is Anti-de Sitter with a charged black-hole to describe finite temperature and density in the boundary theory, and we also include a background dilaton field to generate confinement. The resulting phase diagram in the chemical potential-temperature $\mu-T$ plane is in a quite good agreement with lattice results and effective models of QCD.Comment: 4 pages, 5 figures, version published on PR

Semileptonic B decays into excited charmed mesons from QCD sum rules

Exclusive semileptonic $B$ decays into excited charmed mesons are studied with QCD sum rules in the leading order of heavy quark effective theory. Two universal Isgur-Wise functions \tau and \zeta for semileptonic B decays into four lowest lying excited $D$ mesons ($D_1$, $D_2^*$, $D'_0$, and $D'_1$) are determined. The decay rates and branching ratios for these processes are calculated.Comment: RevTeX, 17 pages including 2 figure

Weak decays of heavy hadron molecules involving the f0(980)

We study weak decays of the charm- and bottom-strange mesons Ds0*(2317), Ds1(2460), Bs0*(5725) and Bs1(5778) with f0(980) in the final state by assuming a hadronic molecule interpretation for their structures. Since in the proposed framework the initial and final states are occupied by hadronic molecules, the predictions for observables can provide a sensitive tool to further test the hadronic molecule structure in future experiments.Comment: 11 pages, 5 figures, accepted for publication in Phys. Rev.

Holographic models and the QCD trace anomaly

Five dimensional dilaton models are considered as possible holographic duals of the pure gauge QCD vacuum. In the framework of these models, the QCD trace anomaly equation is considered. Each quantity appearing in that equation is computed by holographic means. Two exact solutions for different dilaton potentials corresponding to perturbative and non-perturbative beta-functions are studied. It is shown that in the perturbative case, where the beta-function is the QCD one at leading order, the resulting space is not asymptotically AdS. In the non-perturbative case, the model considered presents confinement of static quarks and leads to a non-vanishing gluon condensate, although it does not correspond to an asymptotically free theory. In both cases analyses based on the trace anomaly and on Wilson loops are carried out.Comment: 18 pages 1 figure In this revised version, the section on the analysis of the Wilson loop was improved, and a section was added on the matching of the calculations of the gluon condensate via the d+1 dim action and the Wilson loo

The isospin symmetry breaking effects in Ke4K_{e4} decays

The Fermi-Watson theorem is generalized to the case of two coupled channels with different masses and applied to final state interaction in $K_{e4}$ decays. The impact of considered effect on the phase of the $\pi\pi$ scattering is estimated and shown that it can be crucial for scattering lengths extraction from experimental data on $K_{e4}$ decays

Satellite-to-satellite attitude control of a long-distance spacecraft formation for the Next Generation Gravity Mission

The paperpresentsthedesignandsomesimulatedresultsoftheattitudecontrolofasatelliteformation under studybytheEuropeanSpaceAgencyfortheNextGenerationGravityMission.Theformation consists oftwospacecraftswhich fly morethan200kmapartatanaltitudefromtheEarth'sgroundof between 300and400km.Theattitudecontrolmustkeeptheopticalaxesofthetwospacecraftaligned with amicroradianaccuracy(pointingcontrol).Thisismadepossiblebyspecific opticalsensors accompanyingtheinter-satellitelaserinterferometer,whichisthemainpayloadofthemission.These sensors alloweachspacecrafttoactuateautonomousalignmentafterasuitableacquisitionprocedure. Pointing controlisconstrainedbytheangulardrag-freecontrol,whichisimposedbymissionscience (Earth gravimetryatalowEarthorbit),andmustzerotheangularaccelerationvectorbelow0.01 μrad/s2 in thesciencefrequencyband.Thisismadepossiblebyultrafine accelerometersfromtheGOCE-class, whose measurementsmustbecoordinatedwithattitudesensorstoachievedrag-freeandpointing requirements.EmbeddedModelControlshowshowcoordinationcanbeimplementedaroundthe embedded modelsofthespacecraftattitudeandoftheformationframequaternion.Evidenceand discussion aboutsomecriticalrequirementsarealsoincludedtogetherwithextensivesimulatedresults of twodifferentformationtypes

Signals of Warped Extra Dimensions at the LHC

We discuss the signatures of the spin-2 graviton excitations predicted by the Randall-Sundrum model with one warped extra dimension, in dilepton and diphoton production at LHC. By using a specific angular analysis, we assess the ranges in mass and coupling constant where such gravitons can be discriminated against competitor spin-1 and spin-0 objects, that potentially could manifest themselves in these processes with the same mass and rate of events. Depending on the value of the coupling constant to quarks and leptons, the numerical results indicate graviton identification mass ranges up to 1.1-2.4 TeV and 1.6-3.2 TeV for LHC nominal energy of 14 TeV and time-integrated luminosity of 10 and 100~${\rm fb}^{-1}$, respectively.Comment: 8 pages, Talk given at QCD@Work - International Workshop on QCD - Theory and Experiment, 20 - 23 June, 2010, Martina Franca Ital

Using Heavy Quark Spin Symmetry in Semileptonic BcB_c Decays

The form factors parameterizing the B_c semileptonic matrix elements can be related to a few invariant functions if the decoupling of the spin of the heavy quarks in B_c and in the mesons produced in the semileptonic decays is exploited. We compute the form factors as overlap integral of the meson wave-functions obtained using a QCD relativistic potential model, and give predictions for semileptonic and non-leptonic B_c decay modes. We also discuss possible experimental tests of the heavy quark spin symmetry in B_c decays.Comment: RevTex, 22 pages, 2 figure