22 research outputs found
Muon g-2 through a flavor structure on soft SUSY terms
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 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”
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
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
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 DANE
Investigation at a --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 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 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
Contains fulltext :
172380.pdf (publisher's version ) (Open Access
mixing in the neutral channel pion form factor and its role in comparing with spectral functions
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