169 research outputs found
Semileptonic decays of charmed mesons in the effective action of QCD
Within the framework of phenomenological Lagrangians we construct the
effective action of QCD relevant for the study of semileptonic decays of
charmed mesons. Hence we evaluate the form factors of D -> P(0^-) l^+ nu_l at
leading order in the 1/N_C expansion and, by demanding their QCD-ruled
asymptotic behaviour, we constrain the couplings of the Lagrangian. The
features of the model-independent parameterization of form factors provided and
their relevance for the analysis of experimental data are pointed out.Comment: 1+24 pages, 1 figure. Updated version. Conclusions unchanged.
Accepted for publication in The European Physical Journal
D^0-D^0(bar) mixing in the weak-gauged U(4)_L x U(4)_R Chiral Lagrangian Model
The D^0-D^0(bar) mixing is analyzed in a weak gauged U(4)_L x U(4)_R chiral
lagrangian model where the electroweak interaction is introduced as a gauge
theory over the meson degrees of freedom. This model allows a particular
realization of the G.I.M. mechanism and then could be useful in the study of
processes where G.I.M. suppression is effective. As a test of the model we have
also analyzed the K^0-K^0(bar) mixing. We find \Delta m_K in good agreement
with the experimental result and we show that the D^0-D^0(bar) mixing is very
much suppressed in agreement with previous estimates in the Heavy Quark
expansion framework.Comment: 14 pages, 2 figures, Latex, minor changes in the writing, final
version to be published in Phys. Lett.
decay in the extended NJL model
The width of the decay was calculated
in the extended NJL model. Contact interaction of boson with pion pair as
well as the contribution of the mesons in ground and first radial-exited
states are taken into account. The sum of the contact diagram and diagram with
intermediate meson in the ground state leads to the result which
coincides with the result of the vector-dominance model. Our results are in
satisfactory agreement with experimental data.Comment: 5 pages, 3 figures, 1 tabl
Acta Congregationis Prouinciae Hispaniae, Ordinis Praedicatorum, celebratae in Conuentu sancti Dominici Benauentani Die secunda Octobris ... 1677, sub, R. A. P. N. Fr. Ludouico de Villazan ... Prouinciali eiusdem Prouincia
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Sign.: A-H4Port. con orla tip. y esc. xil. de los Dominico
Acta Capituli Prouincialis Prouinciae Hispaniae Ordinis Praedicatorum : celebrati in Conuentu Sancti Ildefonsi Regalis Taurensis Dominica Deus, qui errantibus, die vigessima tertia Aprilis, Anni Dni 1679, sub R. A. P. N. Fr. Hiacinto Rubio ... Prouinciali electo eiusdem Prouinciae
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Sign.: A-G4Port. con orla tip. y esc. xil. de los Dominico
Relating Andreev Bound States and Supercurrents in Hybrid Josephson Junctions
We investigate superconducting quantum interference devices consisting of two
highly transmissive Josephson junctions coupled by a superconducting loop, all
defined in an epitaxial InAs/Al heterostructure. A novel device design allows
for independent measurements of the Andreev bound state spectrum within the
normal region of a junction and the resulting current-phase relation. We show
that knowledge of the Andreev bound state spectrum alone is enough to derive
the independently measured phase dependent supercurrent. On the other hand, the
opposite relation does not generally hold true as details of the energy
spectrum are averaged out in a critical current measurement. Finally,
quantitative understanding of field dependent spectrum and supercurrent require
taking into account the second junction in the loop and the kinetic inductance
of the epitaxial Al film
Acta Capituli Prouincialis Prouinciae Hispaniae Ordinis Predicatorum, celebrati in Conuentu Sancti Ildefonsi Regalis Taurensis ... die quinta Maij ... 1675, sub R. A. P. N. Fr. Ludouico de Villazan ... Prouinciali electo eiusdem Prouinciae
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Texto fechado en 1675Sign.: A-E4, [ ]2Port. con orla tip. y esc. xil. de los Dominico
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 Standard Model Prediction of the Muon Anomalous Magnetic Moment
This article reviews and updates the Standard Model prediction of the muon
g-2. QED, electroweak and hadronic contributions are presented, and open
questions discussed. The theoretical prediction deviates from the present
experimental value by 2-3 standard deviations, if e+e- annihilation data are
used to evaluate the leading hadronic term.Comment: 30 pages, 8 figures. v2: Updated version to appear in J.Phys.G.
Comments and references added, typo corrected in eq.(17
Evaluation of Haptic Feedback on Bimanually Teleoperated Laparoscopy for Endometriosis Surgery
Robotic minimal invasive surgery is gaining acceptance in surgical care. In contrast with the appreciated 3D vision and enhanced dexterity, haptic feedback is not offered. For this reason robotics is not considered beneficial for delicate interventions such the endometriosis. Overall, haptic feedback remains debatable and yet unproven except for some simple scenarios such as Fundamentals of Laparoscopic Surgery exercises. OBJECTIVE: The present work investigates the benefits of haptic feedback on more complex surgical gestures, manipulating delicate tissue through coordination between multiple instruments. Methods: A new training exercise, “Endometriosis Surgery Exercise” (ESE) has been devised approximating the setting for monocular robotic endometriosis treatment. A bimanual bilateral teleoperation setup was designed for laparoscopic laser surgery. Haptic guidance and haptic feedback are respectively offered to the operator. User experiments have been conducted to i) assess the validity of ESE and to ii) examine possible advantages of haptic technology during execution of bimanual surgery. RESULTS: i) Content and face validity of ESE was established by participating surgeons. Surgeons suggested ESE also as a means to train lasering skills, ii) interaction forces on endometriotic tissue were found to be significantly lower when a bilateral controller is used. Collisions between instruments and the environment were less frequent and so were situations marked as potentially dangerous. CONCLUSION: This study provides some promising results suggesting that haptics may offer a distinct advantage in complex robotic interventions were fragile tissue is manipulated. SIGNIFICANCE: Patients need to know whether it should be incorporated. Improved understanding of the value of haptics is important as current commercial surgical robots are widely used but do not offer haptics
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