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18 results on '"Simao, F. R. A."'

1. Polarization properties of diffractively produced \Lambda_c^+

Author

Arestov, Yu. and Simao, F. R. A.

Subjects
High Energy Physics - Phenomenology
Abstract

The Pomeron-gluon-gluon interaction is considered in the QCD-based model for the charmed baryon production in the process Pomeron + p --> \Lambda_c^+ + X. The polarization of the produced heavy quark is induced effectively through the non-perturbative long-range interaction with the gluon field of the type [sigma*rotA]. The x_F-dependence of \Lambda_c^+ polarization, P_(x_F,p_T), has been studied. Its absolute value depends on the model parameter a and it appears to be sizeable in the wide range of a values: when a ranges from 0.1 to 1.0, the polarization P(x_F,p_T) varies from --0.2 to --0.5 at x_F ~ 0.5 and p_T in the interval 1 - 2 GeV/c., Comment: 10 pages, 4 figures. Talk at 13th Int. Symp. on High Energy Spin Physics, Protvino, Sept. 1998

Published
1998

2. Asymmetry studies in Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ production

Author

Anjos, J. C., Magnin, J., Simao, F. R. A., and Solano, J.

Subjects
High Energy Physics - Phenomenology
Abstract

We present a study on hyperon/anti-hyperon production asymmetries in the framework of the recombination model. The production asymmetries for Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ are studied as a function of x_F. Predictions of the model are compared to preliminary data on hyperon/anti-hyperon production asymmetries in 500 GeV/c pi- p interactions from the Fermilab E791 experiment. The model predicts a growing asymmetry with the number of valence quarks shared by the target and the produced hyperons in the x_F < 0 region. In the positive x_F region, the model predicts constant asymmetries for Lambda 0/Lambda 0-bar and Omega-/Omega+ production and a growing asymmetry with x_F for Xi-/Xi+. We found a qualitatively good agreement between the model predictions and data, showing that recombination is a competitive mechanism in the hadronization process., Comment: One reference corrected

Published
1998
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3. Hyperon production asymmetries in 500 GeV/c pion nucleus interactions

Author

Solano, J., Magnin, J., Simao, F. R. A., and collaboration, E791

Subjects
High Energy Physics - Experiment
Abstract

We present a preliminary study from Fermilab experiment E791 of Lambda^0 / Lambda^0 bar, Xi^- / Xi^+ and Omega^- /Omega^+ production asymmetries from pi^- nucleus interactions at 500 Gev/c. The production asymmetries for these particles are studied as a function of x_F and pt^2. We observed an asymmetry in the target fragmentation region for Lambda^0's larger than that for Xi's, suggesting diquark effects. The asymmetry for Omega's is significatively smaller than for the other two hyperons consistent with the fact that Omega's do not share valence quarks with either the pion or the target particle. In the beam fragmentation region, the asymmetry tends to 0.1 for both Lambda^0's and Xi's. The asymmetries vs pt^2 are approximately constant for the three strange baryons under study., Comment: Typos corrected

Published
1997

4. Production and polarization of $\Lambda_c^+$ and the charm of the proton

Author

Anjos, J. C., Herrera, G., Magnin, J., and Simao, F. R. A.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract

We propose a two-component model involving the parton fusion mechanism and recombination of a $ud$ valence diquark with a sea $c$-quark of the incident proton to describe $\Lambda_c^+$ inclusive production in $pp$ collisions. We also study the polarization of the produced $\Lambda_c^+$ in the framework of the Thomas Precession Model for polarization. We show that a measurement of the $\Lambda_c$ polarization is a sensitive test of its production mechanism. In particular the intrinsic charm model predicts a positive polarization for the $\Lambda_c$ within the framework of the Thomas Precession Model, while according to the model presented here the $\Lambda_c$ polarization should be negative. The measurement of the $\Lambda_c$ polarization provides a close examination of intrinsic charm Fock states in the proton and give interesting information about the hadroproduction of charm., Comment: references to figures corrected. Final version to appear in Physical Review D

Published
1997
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5. The Charm of the Proton and the $\Lambda _c^{+}$ Production

Author

Anjos, J. dos, Herrera, G., Magnin, J., and Simão, F. R. A.

Subjects
High Energy Physics - Phenomenology
Abstract

We propose a two component model for charmed baryon production in $pp$ collisions consisting of the conventional parton fusion mechanism and fragmentation plus quarks recombination in which a $ud$ valence diquark from the proton recombines with a $c$-sea quark to produce a $\Lambda_c^+$. Our two-component model is compared with the intrinsic charm two-component model and experimental data., Comment: 6 pages, LaTex, 2 figures included, aipproc.sty included. Talk presented at Simposio Latino Americano de Fisica de Altas Energias, Merida, Mexico, November 1996

Published
1997
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6. The $\Lambda_0$ Polarization and the Recombination Mechanism

Author

Herrera, G., Magnin, J., Montaño, Luis M., and Simão, F. R. A.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract

We use the recombination and the Thomas Precession Model to obtain a prediction for the $\Lambda _0$ polarization in the $p+p \to \Lambda_0+X$ reaction. We study the effect of the recombination function on the $\Lambda_0$ polarization., Comment: 4 pages, LaTex, 1 figures included, aipproc.sty included. Talk presented at Simposio Latino Americano de Fisica de Altas Energias, Merida, Mexico, November 1996

Published
1997
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7. Study of the decay D0 → K+π

Author

Link, J. M., Reyes, M., Yager, P. M., Anjos, J. C., Bediaga, I., Gobel, C., Magnin, J., Massafferi, A., De Miranda, J. M., Pepe, I. M., Dos Reis, A. C., Simao, F. R. A., Carrillo, S., Casimiro, E., Sanchez-Hernandez, A., Uribe, C., Vazquez, F., Cinquini, L., Cumalat, J. P., O'Reilly, B., Ramirez, J. E., Vaandering, E. W., Butler, J. N., Cheung, H. W. K., Gaines, I., Garbincius, P. H., Garren, L. A., Gottschalk, E., Kasper, P. H., Kreymer, A. E., Kutschke, R., Bianco, S., Fabbri, F. L., Sarwar, S., Zallo, A., Cawlfield, C., Kim, D. Y., Rahimi, A., Wiss, J., Gardner, R., Chung, Y. S., Kang, J. S., B. R., Ko, Kwak, J. W., Lee, K. B., Park, H., Alimonti, G., Boschini, M., Caccianiga, B., D'Angelo, P., Dicorato, M., Dini, P., Giammarchi, M., Inzani, P., Leveraro, F., Malvezzi, S., Menasce, D., Mezzadri, M., Milazzo, L., Moroni, L., Pedrini, D., Pontoglio, C., Prelz, F., Rovere, M., Sala, A., Sala, S., Davenport, T. F., Agostino, L., Arena, V., Boca, G., Bonomi, G., Gianini, G., Liguori, G., Merlo, M., Pantea, D., Ratti, S. P., Riccardi, C., Segoni, I., Viola, L., Vitulo, P., Hernandez, H., Lopez, A. M., Mendez, H., Mendez, L., Mirles, A., Montiel, E., Olaya, D., Paris, A., Quinones, J., Rivera, C., Xiong, W., Zhang, Y., Wilson, J. R., Cho, K., Handler, T., Engh, D., Hosack, M., Johns, W. E., and Nehring, M. S.

Published
2001

8. Preliminary FOCUS results on charmed hadrons spectroscopy

Author

Riccardi, C., Link, J., Reyes, M., Yager, P. M., Anjos, J., Bediaga, I., Gobel, C., Magnin, J., Pepe, I. M., Reis, A. C., Sánchez-Hernández, A., Simao, F. R. A., Carrillo, S., Casimiro, E., Mendez, H., Sheaff, M., Uribe, C., Vasquez, F., Cinquini, L., Cumalat, J. P., Ramirez, J. E., O Reilly, B., Vaandering, E. W., Butler, J. N., Cheung, H. W. K., Gaines, I., Garbincius, P. H., Garren, L. A., Gourlay, S. A., Kasper, P. H., Kreymer, A. E., Kuschke, R., Bianco, S., Fabbri, F. L., Sarwar, S., Zallo, A., Cawlfield, C., Gottschalk, E., Park, K. S., Rahimi, A., Wiss, J., Gardner, R., Chung, Y. S., Kang, J. S., Ko, B. R., Kwak, J. W., Lee, K. B., Myung, S. S., Park, H., Alimonti, G., Boschini, M., Caccianiga, B., Calandrino, A., D Angelo, P., Dicorato, M., Dini, P., Giammarchi, M., Inzani, P., Leveraro, F., Malvezzi, S., Dario Livio Menasce, Mezzadri, M., Milazzo, L., Moroni, L., Pedrini, D., Prelz, F., Sala, A., Sala, S., Davenport Iii, T. F., Arena, V., Boca, G., Bonomi, G., Gianini, G., Liguori, G., Merlo, M., Pantea, D., Ratti, S. P., Viola, L., Vitulo, P., Lopez, A. M., Mendez, L., Mirles, A., Montiel, E., Olaya, D., Rivera, C., Johns, W., Zhang, Y., Copty, N., Purohit, M. V., Wilson, J. R., Cho, K., Handler, T., Engh, D., Hosack, M., Nehring, M., Sales, M., Sheldon, P. D., Webster, M., and Stenson, K.

Published
2000

9. A measurement of lifetime differences in the neutral D-meson system

Author

Link, J. M., Paolone, V. S., Reyes, M., Yager, P. M., Anjos, J. C., Bediaga, I., Gobel, C., Magnin, J., de Miranda, J. M., Pepe, I. M., dos Reis, A. C., Simao, F. R. A., Vale, M. A., Carrillo, S., Casimiro, E., Mendez, H., Sanchez Hernandez, A., Uribe, C., Vazquez, F., Cinquini, L., Cumalat, J. P., Ramirez, J. E., O'Reilly, B., Vaandering, E. W., Butler, J. N., Cheung, H. W. K., Gaines, I., Garbincius, P. H., Garren, L. A., Gottschalk, E., Gourlay, S. A., Kasper, P. H., Kreymer, A. E., Kutschke, R., Bianco, S., Fabbri, F. L., Sarwar, S., Zallo, A., Cawlfield, C., Kim, D. Y., Park, K. S., Rahimi, A., Wiss, J., Gardner, R., Chung, Y. S., Kang, J. S., B. R., Ko, Kwak, J. W., Lee, K. B., Myung, S. S., Park, H., Alimonti, G., Boschini, M., Brambilla, D., Caccianiga, B., Calandrino, A., D'Angelo, P., Dicorato, M., Dini, P., Giammarchi, M., Inzani, P., Leveraro, F., Malvezzi, S., Menasce, D., Mezzadri, M., Milazzo, L., Moroni, L., Pedrini, D., Prelz, F., Revere, M., Sala, A., Sala, S., Davenport, T. F., Arena, V., Boca, G., Bonomi, Germano, Gianini, G., Liguori, G., Merlo, M., Pantea, D., Ratti, S. P., Riccardi, C., Torre, P., Viola, L., Vitulo, P., Hernandez, H., Lopez, A. M., Mendez, L., Mirles, A., Montiel, E., Olaya, D., Quinones, J., Rivera, C., Zhang, Y., Copty, N., Purohit, M., Wilson, J. R., Cho, K., Handler, T., Engh, D., Johns, W. E., Hosack, M., Nehring, M. S., Sales, M., Sheldon, P. D., Stenson, K., Webster, M. S., Sheaff, M., and Kwon, Y. J.

Published
2000

10. Preliminary results from FOCUS

Author

Lopez, A. M., Link, J., Reyes, M., Yager, P. M., Anjos, J. C., Bediaga, I., Gobel, C., Magnin, J., Pepe, I. M., Reis, A. C., Sanchez-Hernandez, A., Simao, F. R. A., Carrillo, S., Casimiro, E., Mendez, H., Sheaff, M., Uribe, C., Vazquez, F., Cinquini, L., Cumalat, J. P., O Reilly, B., Vaandering, E., Butler, J. N., Cheung, H. W. K., Gaines, I., Garbincius, P. H., Garren, L. A., Gourlay, S. A., Kasper, P. H., Kreymer, A. E., Kutschke, R., Bianco, S., Fabbri, F. L., Sarwar, S., Zallo, A., Cawlfield, C., Gardner, R., Gottschalk, E., Park, K. S., Rahimi, A., Wiss, J., Chung, Y. S., Kang, J. S., Ko, B. R., Kwak, J. W., Lee, K. B., Myung, S. S., Park, H., Alimonti, G., Boschini, M., Caccianiga, B., Calandrino, A., D Angelo, P., Dicorato, M., Dini, P., Giammarchi, M., Inzani, P., Leveraro, F., Sandra Malvezzi, Mcnasce, D., Mezzadri, M., Milazzo, L., Moroni, L., Pedrini, D., Prelz, F., Sala, A., Sala, S., Davenport, T. F., Arena, V., Boca, G., Bonomi, G., Gianini, G., Liguori, G., Merlo, M., Pantea, D., Ratti, S. P., Riccardi, C., Viola, L., Vitulo, P., Hernandez, H., Mirles, A., Montiel, E., Olaya, D., Ramirez, J. E., Rivera, C., Zhang, Y., Copty, N., Johns, W. E., Purohit, M., Wilson, J. R., Cho, K., Handler, T., Engh, D., Hosack, M., Nehring, M., Sales, M., Sheldon, P. D., Webster, M., Stenson, K., and Kwon, Y.

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, High Energy Physics::Phenomenology, High Energy Physics::Experiment, Fermilab, Spectroscopy, Focus (optics)
Abstract

Fermilab's FOCUS experiment obtained a very high statistics sample of charmed particle decays. Preliminary results on spectroscopy, doubly Cabibbo suppressed decays and lifetimes are presented.

Published
2000

11. Measurements of the Sigma(0)(c) and Sigma(++)(c) mass splittings

Author

Link, J. M., Paolone, V. S., Reyes, M., Yager, P. M., Anjos, J. C., Bediaga, I., Gobel, C., Magnin, J., de Miranda, J. M., Pepe, I. M., dos Reis, A. C., Simao, F. R. A., Carrillo, S., Casimiro, E., Mendez, H., Sanchez Hernandez, A., Uribe, C., Vazquez, F., Cinquini, L., Cumalat, J. P., Ramirez, J. E., O'Reilly, B., Vaandering, E. W., Butler, J. N., Cheung, H. W. K., Gaines, I., Garbincius, P. H., Garren, L. A., Gottschalk, E., Gourlay, S. A., Kasper, P. H., Kreymer, A. E., Bianco, S., Fabbri, F. L., Sarwar, S., Zallo, A., Cawlfield, C., Kutschke, R., Kim, D. Y., Park, K. S., Rahimi, A., Wiss, J., Gardner, R., Chung, Y. S., Kang, J. S., B. R., Ko, Kwak, J. W., Lee, K. B., Myung, S. S., Park, H., Alimonti, G., Boschini, M., Brambilla, D., Caccianiga, B., Calandrino, A., D'Angelo, P., Dicorato, M., Dini, P., Giammarchi, M., Inzani, P., Leveraro, F., Malvezzi, S., Menasce, D., Mezzadri, M., Milazzo, L., Moroni, L., Pedrini, D., Prelz, F., Rovere, M., Sala, A., Sala, S., Davenport, T. F., Arena, V., Boca, G., Bonomi, Germano, Gianini, G., Liguori, G., Merlo, M., Pantea, D., Ratti, S. P., Riccardi, C., Torre, P., Viola, L., Vitulo, P., Hernandez, H., Lopez, A. M., Mendez, L., Mirles, A., Montiel, E., Olaya, D., Quinones, J., Rivera, C., Zhang, Y., Copty, N., Purohit, M., Wilson, J. R., Cho, K., Handler, T., Engh, D., Johns, W. E., Hosack, M., Nehring, M. S., Sales, M., Sheldon, P. D., Stenson, K., Webster, M. S., Sheaff, M., and Kwon, Y. J.

Published
2000

12. Polarization properties of diffractively produced ��_c^+

Author

Arestov, Yu. and Simao, F. R. A.

Subjects
High Energy Physics - Phenomenology (hep-ph), High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The Pomeron-gluon-gluon interaction is considered in the QCD-based model for the charmed baryon production in the process Pomeron + p --> ��_c^+ + X. The polarization of the produced heavy quark is induced effectively through the non-perturbative long-range interaction with the gluon field of the type [sigma*rotA]. The x_F-dependence of ��_c^+ polarization, P_(x_F,p_T), has been studied. Its absolute value depends on the model parameter a and it appears to be sizeable in the wide range of a values: when a ranges from 0.1 to 1.0, the polarization P(x_F,p_T) varies from --0.2 to --0.5 at x_F ~ 0.5 and p_T in the interval 1 - 2 GeV/c., 10 pages, 4 figures. Talk at 13th Int. Symp. on High Energy Spin Physics, Protvino, Sept. 1998

Published
1998
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