Showing papers by "Alberto Santoro published in 1990"

Measurement of the form-factors in the decay D+ ---> anti-K*0 e+ electron-neutrino

Abstract: We have measured the three form factors governing the decay {ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}, observed in Fermilab photoproduction experiment E691, using the complete decay distribution of the data. The results are {ital A}{sub 1}(0)=0.46{plus minus}0.05{plus minus}0.05, {ital A}{sub 2}(0)=0.0{plus minus}0.2{plus minus}0.1, and {ital V}(0)=0.9{plus minus}0.3{plus minus}0.1 for the two axial-vector and the vector form factors, respectively. The {ital {bar K}} {sup *0} mesons have a ratio of longitudinal to transverse polarization of 1.8{sub {minus}0.4}{sup +0.6}{plus minus}0.3. These results are significantly different from values predicted by a number of different models.

Field theory and particle physics

Abstract: This book contains the proceedings of the topics covered during the fifth Jorge Andre Swieca Summer School. The first part of the book collects the material devoted to quantum field theory. There were four courses on methods in Field Theory; H. O. Girotti lectured on constrained dynamics, R. Jackiw on the Schrodinger representation in Field Theory, S.-Y. Pi on the application of this representation to quantum fields in a Robertson-Walker spacetime, and L. Vinet on Berry Connections. There were three courses on Conformal Field Theory: I. Todorov focused on the problem of construction and classification of conformal field theories. Lattice models, two-dimensional S matrices and conformal field theory were looked from the unifying perspective of the Yang-Baxter algebras in the lectures given by M. Karowski. Parasupersymmetric quantum mechanics was discussed in the lectures by L. Vinet. Besides those courses, there was an introduction to string field theory given by G. Horowitz. There were also three seminars: F. Schaposnik reported on recent applications of topological methods in field theory, P. Gerbert gave a seminar on three dimensional gravity and V. Kurak talked on two dimensional parafermionic models. The second part of this proceedings is devoted to phenomenology. There were three coursesmore » on Particle Physics: Dan Green lectured on collider physics, E. Predrazzi on strong interactions and G. Cohen-Tanoudji on the use of strings in strong interactions.« less

Photon-gluon-fusion analysis of charm photoproduction.

Abstract: Results on the photoproduction of 10 000 fully reconstructed charmed particles from the ${10}^{8}$ recorded triggers of Fermilab experiment E691 have been analyzed in the photon-gluon-fusion model. We find that the total cross section, its rise with energy, and the ${\mathit{p}}_{\mathit{T}}^{2}$ and ${\mathit{x}}_{\mathit{F}}$ distributions can be explained by a high mass for the charm quark (${\mathit{m}}_{\mathit{c}}$=1.${74}_{\mathrm{\ensuremath{-}}0.18}^{+0.13}$ GeV/${\mathit{c}}^{2}$) and a soft-gluon distribution [G(x)\ensuremath{\sim}(1-x${)}_{\mathit{g}}^{\mathit{n}}$, where ${\mathit{n}}_{\mathit{g}}$=7.1\ifmmode\pm\else\textpm\fi{}2.2].

Study of Ds+--> phie+ nu e and the absolute Ds+--> phi pi + branching fraction.

Abstract: We have searched for the decay {ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}} in data from the Fermilab charm photoproduction experiment E691. The resulting upper limit is {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}}){lt}0.45{ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +}). Since the branching fraction for {ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}} can be calculated from the measured branching fraction {ital B}({ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}) to be (1.7{plus minus}0.3)%, this implies a 90%-confidence-level lower limit on {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +}) of 3.4%.

Experimental results on the decays D-->K4 pi.

Abstract: We report measurements of the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup {minus}}{pi}{sup +}{pi}{sup 0}, {ital D}{sup 0}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup {minus}}{pi}{sup +}{pi}{sup {minus}}, and {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}} from the Fermilab photoproduction experiment E-691. The resonant subcomponent fractions are also analyzed. Upper limits are obtained for the two-body decays {ital D}{sup 0}{r arrow}{ital {bar K}} {sup *0}{omega} and {ital D}{sup 0}{r arrow}{ital {bar K}} {sup *0}{eta}.

Study of decays of the Lambda c

Abstract: We report measurements of the decays {Lambda}{sub {ital c}}{sup +}{r arrow}p{bar K} {sup 0}, {Lambda}{sub {ital c}}{sup +}{r arrow}p{bar K} {sup 0}{pi}{sup +}{pi}{sup {minus}}, {Lambda}{sub {ital c}}{sup +}{r arrow}{Lambda}{sup 0}{pi}{sup +}, and {Lambda}{sub {ital c}}{sup +}{r arrow}{Lambda}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}} from Fermilab photoproduction experiment E691. We have measured the relative branching ratios {ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}p{bar K}{sup 0})/{ital B} ({Lambda}{sub {ital c}}{sup +}{r arrow}pK{sup {minus}}{pi}{sup +})=0.55{plus minus}0.17{plus minus}0.14, {ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}{Lambda}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}0)/ {ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}{ital pK}{sup {minus}}{pi}{sup +})=0.82{plus minus}0.29{plus minus}0.27, {ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}{Lambda}{sup 0}{pi}{sup +})/{ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}{ital pK}{sup {minus}}{pi}{sup +}){lt}0.33 at 90% confidence level, and {ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}p{bar K} {sup 0}{pi}{sup +}{pi}{sup {minus}})/{ital B}({Lambda}{sub {ital c}}{sup +}{r arrow}{ital pK}{sup {minus}}{pi}{sup +}){lt}1.7 at 90% confidence level.

Hadroproduction of charm at Fermilab E769

Abstract: Experiment E769 at Fermilab obtained charm hadroproduction data during the 1987-88 Fixed Target running period with a 250 GeV hadron beam incident on thin target foils of Be, Al, Cu, and W. From an analysis of 25% of the recorded 400M trigger sample we have explored the Feynman x, p{sub t}{sup 2} and the atomic number dependence of charm quark production using samples of D{sup +} and D{sup 0} mesons. 7 refs., 4 figs.

Study of the decays D-->K-bar0 pi + and D-->K-bar0K+

Abstract: We report measurements of the decays ${D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{+}$, ${D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+}$, and $D_{s}^{}{}_{}{}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+}$ from Fermilab photoproduction experiment E691. The relative branching fractions obtained are $\frac{B({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{+})}{B({D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})}=0.274\ifmmode\pm\else\textpm\fi{}0.030\ifmmode\pm\else\textpm\fi{}0.031$, $\frac{B({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+})}{B({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{+})}=0.271\ifmmode\pm\else\textpm\fi{}0.065\ifmmode\pm\else\textpm\fi{}0.039$, and $\frac{B(D_{s}^{}{}_{}{}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+})}{B(D_{s}^{}{}_{}{}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{\ensuremath{\pi}}^{+})}=1.15\ifmmode\pm\else\textpm\fi{}0.31\ifmmode\pm\else\textpm\fi{}0.19$.