2,255 research outputs found

    Heavy-meson physics and flavour violation with a single generation

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    We study flavour-violating processes which involve heavy B- and D-mesons and are mediated by Kaluza-Klein modes of gauge bosons in a previously suggested model where three generations of the Standard Model fermions originate from a single generation in six dimensions. We find the bound on the size R of the extra spatial dimensions 1/R>3.3 TeV, which arises from the three-body decay B_s to K mu e. Due to the still too low statistics this bound is much less stringent than the constraint arising from K to mu e, 1/R>64 TeV, which was found in a previous work (Frere et al., JHEP, 2003). Nevertheless, we argue that a clear signature of the model would be an observation of K to mu e and B_s to K mu e decays without observations of other flavour and lepton number changing processes at the same precision level.Comment: 15 page

    Central pseudoscalar production in pp scattering and the gluon contribution to the proton spin

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    Central pseudoscalar production in pppp scattering is suppressed at small values of QQ_\perp, where QQ is defined as the difference between the momenta transferred from the two protons. Such a behaviour is expected if the production occurs through the fusion of two vectors. Photon exchange could provide the dominant contribution at low transferred momenta, but we argue that an extension of the experiment could probe the gluon contribution to the proton spin.Comment: 12 pages, 2 figures and 3 tables, uses epsf.sty. Added references and tables. Minor changes include

    Neutrino Mass Patterns within the See-saw Model from Multi-localization along Extra Dimensions

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    We study a multi-localization model for charged leptons and neutrinos, including the possibility of a see-saw mechanism. This framework offers the opportunity to allow for realistic solutions in a consistent model without fine-tuning of parameters, even if quarks are also considered. Those solutions predict that the large Majorana mass eigenvalues for right-handed neutrinos are of the same order of magnitude, although this almost common mass can span a large range (bounded from above by 1012GeV\sim 10^{12}{\rm GeV}). The model also predicts Majorana masses between 102eV\sim 10^{-2}{\rm eV} and $\sim 5 \ 10^{-2}{\rm eV}forthelefthandedneutrinos,bothinthenormalandinvertedmasshierarchycases.Thismassintervalcorrespondstosensitivitieswhicharereachablebyproposedneutrinolessdouble for the left-handed neutrinos, both in the normal and inverted mass hierarchy cases. This mass interval corresponds to sensitivities which are reachable by proposed neutrinoless double \betadecayexperiments.Thepreferredrangeforleptonicmixingangle decay experiments. The preferred range for leptonic mixing angle \theta_{13}is: is: 10^{-2} \lesssim \sin \theta_{13} \lesssim 10^{-1}$, but smaller values are not totally excluded by the model.Comment: 36 pages, 8 figure

    Neutrino masses with a single generation in the bulk

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    In a class of multidimensional models, topology of the thick brane provides three chiral fermionic families with hierarchical masses and mixings in the effective four-dimensional theory, while the full model contains a single vector-like generation. We discuss how to incorporate three non-degenerate neutrino masses in these models with the help of only one singlet bulk fermion.Comment: 16 pages, 1 EPS figur

    On the production of a lepton pair in the collision of ultrarelativistic neutral particle with nonzero magnetic moment with nuclei

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    Explicit formulas which describe muon pair production in reaction γνμ+μν\gamma\nu \to \mu^+ \mu^- \nu through neutrino magnetic moment are obtained and used to derive in the leading approximation cross section of muon pair production in νN\nu N-scattering due to neutrino magnetic moment. This cross section appears to be proportional to log4Eν\log^4 E_{\nu}. Comparison with experimental data on tridents production provides an upper bound μνμ<4108μB\mu_{\nu_{\mu}} < 4*10^{-8} \mu_B, which is approximately two orders of magnitude weaker than that from νμe\nu_{\mu}e elastic scattering data.Comment: 9 pages, 4 figures, numerical estimates are improve

    Development and characterisation of a novel LDMOS macro-model for smart power applications

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