22 research outputs found

    Muon g-2 through a flavor structure on soft SUSY terms

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    In this work we analyze the possibility to explain the muon anomalous magnetic moment discrepancy within theory and experiment through lepton flavor violation processes. We propose a flavor extended MSSM by considering a hierarchical family structure for the trilinear scalar Soft-Supersymmetric terms of the Lagranagian, present at the SUSY breaking scale. We obtain analytical results for the rotation mass matrix, with the consequence of having non-universal slepton masses and the possibility of leptonic flavour mixing. The one-loop supersymmetric contributions to the leptonic flavour violating process τμγ\tau \to \mu\gamma are calculated in the physical basis, with slepton flavour mixed states, instead of using the well known Mass Insertion Method. We present the regions in parameter space where the muon g-2 problem is either entirely solved or partially reduced through the contribution of these flavor violating processes.Comment: 21 pages, 7 figures. Changes on version 3: In order to obtain the complete result for muon g-2 in the limit of non-flavor violation we added the terms given in the appendix. We redid the graphics and numerical analysis including these changes. We also corrected some typos and changed the order of figure

    The Experience in Nicaragua: Childhood Leukemia in Low Income Countries—The Main Cause of Late Diagnosis May Be “Medical Delay”

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    Background. The event-free survival for pediatric leukemia in low-income Countries is much lower than in high-income countries. Late diagnosis, which is regarded as a contributing factor, may be due to “parental” or “medical” delay. Procedures. The present study analyses determinants of lag time from first symptoms to diagnosis of leukemia, comparing pediatric (0–16 years old) patients in two referral centers, one in Nicaragua and one in Italy. An observational retrospective study was conducted to assess factors influencing the time to diagnosis. Results. 81 charts of children diagnosed with acute myeloid leukemia or lymphoblastic leukemia were analyzed from each centre. Median lag time to diagnosis was higher in Nicaragua than in Italy (29 versus 14 days, P < 0.001) and it was mainly due to “physician delay” (16.5 versus 7 days, P < 0.001), whereas “patient delay” from symptoms to first medical assessment was similar in the two centers (7 versus 5 days, P = 0.27). Moreover, median lag time from symptoms to diagnosis was decreased in Nicaraguan districts were a specific training program upon childhood oncological diseases was carried out (20.5 versus 40 days, P = 0.0019). Conclusions. Our study shows that delay in diagnosis of childhood leukemia is mainly associated with “physician delay” and it may be overcome by programs of continuous medical education

    The Discrepancy Between tau and e+e- Spectral Functions Revisited and the Consequences for the Muon Magnetic Anomaly

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    We revisit the procedure for comparing the pi pi spectral function measured in tau decays to that obtained in e+e- annihilation. We re-examine the isospin-breaking corrections using new experimental and theoretical input, and find improved agreement between the tau- --> pi- pi0 nu_tau branching fraction measurement and its prediction using the isospin-breaking-corrected e+e- --> pi+pi- spectral function, though not resolving all discrepancies. We recompute the lowest order hadronic contributions to the muon g-2 using e+e- and tau data with the new corrections, and find a reduced difference between the two evaluations. The new tau-based estimate of the muon magnetic anomaly is found to be 1.9 standard deviations lower than the direct measurement.Comment: 10 pages, 6 figures, submitted to Eur. Phys. J. C; (v2): Revised version with improved and uniform treatment of tau and e+e- data with HVPTools and a few minor bug fixes; (v3): Final version accepted for publicatio

    The Dipion Mass Spectrum In e+e- Annihilation and tau Decay: A Dynamical (rho0, omega, phi) Mixing Approach

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    We readdress the problem of finding a simultaneous description of the pion form factor data in e+e- annihilations and in tau decays. For this purpose, we work in the framework of the Hidden Local Symmetry (HLS) Lagrangian and modify the vector meson mass term by including the pion and kaon loop contributions. This leads us to define the physical rho, omega and phi fields as linear combinations of their ideal partners, with coefficients being meromorphic functions of s, the square of the 4--momentum flowing into the vector meson lines. This allows us to define a dynamical, i.e. s-dependent, vector meson mixing scheme. The model is overconstrained by extending the framework in order to include the description of all meson radiative (V P gamma and P gamma gamma couplings) and leptonic (Ve+e- couplings) decays and also the isospin breaking (omega/ phi --> pi+ pi-) decay modes. The model provides a simultaneous, consistent and good description of the e+e- and tau dipion spectra. The expression for pion form factor in the latter case is derived from those in the former case by switching off the isospin breaking effects specific to e+e- and switching on those for tau decays. Besides, the model also provides a good account of all decay modes of the form V P gamma, Pgamma gamma as well as the isospin breaking decay modes. It leads us to propose new reference values for the rho^0 --> e+ e- and omega --> pi+ pi- partial widths which are part of our description of the pion form factor. Other topics (phi --> K anti K, the rho meson mass and width parameters) are briefly discussed. Therefore, we confirm the 3.3 sigma discrepancy between the theoretical estimate of a_mu based on e+e- and its direct BNL measurement.Comment: 71 pages, 8 figures. Accepted by EPJ C. Version 3: correct minor typos, minor changes spread out into the text. Extension of Sections 12.2 and 12.3.5 and introduction of the new Appendix

    Physics with the KLOE-2 experiment at the upgraded DAϕ\phiNE

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    Investigation at a ϕ\phi--factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta^\prime mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the e+ee^+ e^- physics in the continuum with the measurements of (multi)hadronic cross sections and the study of gamma gamma processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added reference to section

    Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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    Contains fulltext : 172380.pdf (publisher's version ) (Open Access

    ρ0γ\rho^0 - \gamma mixing in the neutral channel pion form factor Fπ(e)(s)F^{(e)}_{\pi}(s) and its role in comparing e+ee^+ e^- with τ\tau spectral functions

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    We study the effect of rho^0-gamma mixing in e^+e^- to pi^+pi^- and its relevance for the comparison of the square modulus of the pion from-factor |F^(e)_pi|^2, as measured in e^+e^- annihilation experiments, and |F^(tau)_pi|^2 the corresponding quantity obtained after accounting for known isospin breaking effects by an isospin rotation from the tau-decay spectra. After correcting the tau data for the missing rho-gamma mixing contribution, besides the other known isospin symmetry violating corrections, the pi pi I=1 part of the hadronic vacuum polarization contribution to the muon g-2 are fully compatible between tau based and e^+e^- based evaluations. tau data thus confirm result obtained with e^+e^- data. Our evaluation based on all e^+e^- data including more recent BaBar and KLOE data yields a_mu^(had)=690.75(4.72) x 10^{-10} (e^+e^- based), while including tau data we find a_mu^(had)=690.96(4.65) X 10^{-10} (e^+e^-+tau based). This backs the ~3 sigma deviation between theory and experiment. For the tau di-pion branching fraction we find B^{CVC}_{pi pi^0}=25.20 \pm0.0.17\pm0.28 from e^+e^-+CVC, while B_{pi pi^0}=25.34\pm0.0.06\pm0.08 is evaluated directly from the tau spectra.Comment: 18 pages, 18 figures, Fig.2 added,Refs. 3,12,14 added, text referring to Refs. 13,14 corrected, typos correcte
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