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${{\mathit \Lambda}_{{c}}^{+}}$ DECAY PARAMETERS

See the note on ``Baryon Decay Parameters'' in the neutron Listings.

$\alpha $ FOR ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \ell}^{+}}{{\mathit \nu}_{{{{\mathit \ell}}}}}$

INSPIRE   PDGID:

S033ALC

The experiments don't cover the complete (or same incomplete) $\mathit M$( ${{\mathit \Lambda}}{{\mathit \ell}^{+}}$ ) range, but we average them together anyway.

VALUE EVTS DOCUMENT ID TECN  COMMENT $\bf{ -0.86 \pm0.04}$ OUR AVERAGE $-0.86$ $\pm0.03$ $\pm0.02$ 3201 1 HINSON 2005 CLEO ${{\mathit e}^{+}}{{\mathit e}^{-}}$ $\approx{}{{\mathit \Upsilon}{(4S)}}$ $-0.91$ $\pm0.42$ $\pm0.25$ 2 ALBRECHT 1994 B ARG ${{\mathit e}^{+}}{{\mathit e}^{-}}$ $\approx{}$10 GeV • • We do not use the following data for averages, fits, limits, etc. • • $-0.82$ ${}^{+0.09}_{-0.06}$ ${}^{+0.06}_{-0.03}$ 700 3 CRAWFORD 1995 CLE2 See HINSON 2005 $-0.89$ ${}^{+0.17}_{-0.11}$ ${}^{+0.09}_{-0.05}$ 350 4 BERGFELD 1994 CLE2 See CRAWFORD 1995 1  HINSON 2005 measures the form-factor ratio $\mathit R{}\equiv\mathit f_{2}/\mathit f_{1}$ for ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ events to be $-0.31$ $\pm0.05$ $\pm0.04$ and the pole mass to be $2.21$ $\pm0.08$ $\pm0.14$ GeV/c${}^{2}$, and from these calculates $\alpha $, averaged over $\mathit q{}^{2}$, where $\langle \mathit q{}^{2}\rangle ~=~0.67~$(GeV/c)${}^{2}$. 2  ALBRECHT 1994B uses ${{\mathit \Lambda}}{{\mathit e}^{+}}$ and ${{\mathit \Lambda}}{{\mathit \mu}^{+}}$ events in the mass range $1.85<\mathit M$( ${{\mathit \Lambda}}{{\mathit \ell}^{+}}$ )$<2.20$ GeV. 3  CRAWFORD 1995 measures the form-factor ratio $\mathit R{}\equiv\mathit f_{2}/\mathit f_{1}$ for ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ events to be $-0.25$ $\pm0.14$ $\pm0.08$ and from this calculates $\alpha $, averaged over $\mathit q{}^{2}$, to be the above. 4  BERGFELD 1994 uses ${{\mathit \Lambda}}{{\mathit e}^{+}}$ events.

References:

HINSON 2005 PRL 94 191801 Improved Measurement of the Form-Factors in the Decay ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ CRAWFORD 1995 PRL 75 624 Form Factor Ratio Measurement in ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}$ ALBRECHT 1994B PL B326 320 Observation of Polarization Effects in ${{\mathit \Lambda}_{{c}}^{+}}$ Semileptonic Decay BERGFELD 1994 PL B323 219 Study of the Decay ${{\mathit \Lambda}_{{c}}^{+}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \ell}^{+}}{{\mathit \nu}_{{{{\mathit \ell}}}}}$

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