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Search Results: 1 - 10 of 7412 matches for " Francesco Simula "
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D-meson decay constants and a check of factorization in non-leptonic B-decays
Damir Becirevic,Vittorio Lubicz,Francesco Sanfilippo,Silvano Simula,Cecilia Tarantino
Physics , 2012, DOI: 10.1007/JHEP02(2012)042
Abstract: We compute the vector meson decay constants fD*, fDs* from the simulation of twisted mass QCD on the lattice with Nf = 2 dynamical quarks. When combining their values with the pseudoscalar D(s)-meson decay constants, we were able (i) to show that the heavy quark spin symmetry breaking effects with the charm quark are large, fDs*/fDs = 1.26(3), and (ii) to check the factorization approximation in a few specific B-meson non-leptonic decay modes. Besides our main results, fD* = 278 \pm 13 \pm 10 MeV, and fDs* = 311 \pm 9 MeV, other phenomenologically interesting results of this paper are: fDs*/fD* = 1.16 \pm 0.02 \pm 0.06, fDs*/fD = 1.46 \pm 0.05 \pm 0.06, and fDs/fD* = 0.89 \pm 0.02 \pm 0.03. Finally, we correct the value for B(B0 \rightarrow D+ pi-) quoted by PDG, and find B(B0 \rightarrow D+ pi-) = (7.8 \pm 1.4) \times 10-7. Alternatively, by using the ratios discussed in this paper, we obtain B(B0 \rightarrow D+ pi-) = (8.3 \pm 1.0 \pm 0.8)\times10-7.
Irreversible AE1 Tyrosine Phosphorylation Leads to Membrane Vesiculation in G6PD Deficient Red Cells
Antonella Pantaleo,Emanuela Ferru,Franco Carta,Franca Mannu,Luigi F. Simula,Amina Khadjavi,Proto Pippia,Francesco Turrini
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015847
Abstract: While G6PD deficiency is one of the major causes of acute hemolytic anemia, the membrane changes leading to red cell lysis have not been extensively studied. New findings concerning the mechanisms of G6PD deficient red cell destruction may facilitate our understanding of the large individual variations in susceptibility to pro-oxidant compounds and aid the prediction of the hemolytic activity of new drugs.
$K$ and $D$ oscillations in the Standard Model and its extensions from $N_f=2+1+1$ Twisted Mass LQCD
Nuria Carrasco,Petros Dimopoulos,Roberto Frezzotti,Vicent Giménez,Vittorio Lubicz,Giancarlo Rossi,Francesco Sanfilippo,Silvano Simula,Cecilia Tarantino
Physics , 2013,
Abstract: We present the first $N_f=2+1+1$ results for the matrix elements of the operators describing neutral $K$ and $D$ mixing in the Standard Model and its extensions. The combination of maximally twisted sea quarks and Osterwalder-Seiler valence quarks ensures $\mathcal{O}(a)$-improvement and continuum like renormalization pattern. We have used the $N_f=2+1+1$ dynamical quark gauge configurations generated by ETMC. Simulations include three lattice spacings in the interval $[0.06:0.09]$ fm and pseudoscalar meson masses in the range $[230:500]$ MeV. Our results are extrapolated to the continuum limit and to the physical quark masses. The calculation of the renormalization constants has been performed non-perturbatively in the RI-MOM scheme.
Calculation of the Isgur-Wise function from a light-front constituent quark model
S. Simula
Physics , 1996, DOI: 10.1016/0370-2693(96)00127-X
Abstract: The space-like elastic form factor of heavy-light pseudoscalar mesons is investigated within a light-front constituent quark model in order to evaluate the Isgur-Wise form factor. The relativistic composition of the constituent quark spins is properly taken into account using the Melosh rotations, and various heavy-meson wave function are considered, including the eigenfunctions of an effective light-front mass operator reproducing meson mass spectra. It is shown that in a wide range of values of the recoil the Isgur-Wise form factor exhibits a moderate dependence upon the choice of the heavy-meson wave function and is mainly governed by the effects of the confinement scale.
Heavy-quark binding and kinetic energies in heavy-light mesons and the constituent quark model
Silvano Simula
Physics , 1997, DOI: 10.1016/S0370-2693(97)01288-4
Abstract: The spin-averaged binding energy and the hyperfine mass splitting of heavy-light mesons are investigated within the constituent quark model as a function of the inverse heavy-quark mass. It is shown that the so-called heavy-quark kinetic energy, -lambda1 / 2mQ, may differ remarkably from the non-relativistic expectation / 2mQ, thanks to relativistic effects in the effective interquark potential for heavy-light mesons, which may yield substantial 1 / mQ corrections to the heavy-quark static limit. The determination of the difference of the hadronic parameter lambda1 in the B(u(d)) and B(c) mesons can provide information about the strength of relativistic effects in the interquark interaction.
SU(3)-breaking effects in hyperon semileptonic decays
Silvano Simula
Physics , 2006,
Abstract: We present the first quenched lattice QCD study of all the vector and axial form factors relevant for the hyperon semileptonic decay Sigma- -> n l nu.
Investigation of the neutron structure function via semi-inclusive deep inelastic electron scattering off the deuteron
Silvano Simula
Physics , 1996,
Abstract: The production of slow nucleons in semi-inclusive deep inelastic electron scattering off the deuteron is investigated in the region $x \gsim 0.3$ for kinematical conditions accessible at $HERA$. Within the spectator mechanism the semi-inclusive cross section exhibits a scaling property, which can be used as a model-independent test of the dominance of the spectator mechanism itself, providing in this way an interesting tool to investigate the neutron structure function. The possibility of extracting model-independent information on the neutron to proton structure function ratio from semi-inclusive experiments is also illustrated.
Tagged nuclear structure functions with $HERMES$
Silvano Simula
Physics , 1996,
Abstract: The production of slow nucleons in semi-inclusive deep inelastic electron scattering off nuclei, $A(e, e'N)X$, is analyzed for kinematical conditions accessible at $HERA$ with the $HERMES$ detector. The sensitivity of the semi-inclusive cross section to possible medium-dependent modifications of the nucleon structure function is illustrated.
Nucleon-Nucleon Correlations and Multiquark Cluster Effects in Deep Inelastic Electron Scattering off Few-Nucleon Systems at $x>1$
S. Simula
Physics , 1995,
Abstract: Inclusive $A(e,e')X$ and semi-inclusive $A(e,e'N)X$ deep inelastic electron scattering processes off few-nucleon systems are investigated at $x > 1$, showing some of the relevant features of the cross section which are sensitive to the effects arising from nucleon-nucleon correlations and possible exotic multiquark cluster configurations at short internucleon separations.
Nucleon-Nucleon Correlations and Inclusive Electron Scattering off Few-Nucleon Systems at $x>1$
S. Simula
Physics , 1995,
Abstract: Inclusive electron scattering off few-nucleon systems is investigated at $x>1$ and high momentum transfer, including the contributions from quasi-elastic and deep inelastic scattering processes. It is shown that at $x>1$ the inclusive cross section is dominated by the process of virtual photon absorption on a pair of correlated nucleons both in case of quasi-elastic and deep inelastic scattering events. The sensitivity of the nuclear response to the effects arising from the possible presence of multiquark cluster configurations at short internucleon separations as well as from possible medium-dependent modifications of the nucleon structure function, is illustrated.
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