Effects of charged Higgs bosons in the deep

inelastic process nt N ® t^- X and the possibility

of detecting tau-neutrinos at cosmic neutrino

detectors

M I PEDRAZA-MORALES¹, A ROSADO^1,* and H SALAZAR²

¹Instituto de F\'{\i}sica, BUAP. Apdo. Postal J-48, C.P. 72570 Puebla, Pue., M\'exico,

²FCFM-BUAP. Apdo. Postal 1364, C.P. 72000 Puebla, Pue., M\'exico

^*Corresponding author. E-mail: rosado@sirio.ifuap.buap.mx}

Abstract. We study the deep inelastic process $\nu_{\tau} + {\cal N}

\to \tau^{-} + X$ (with ${\cal N} \equiv (n+p)/2$ an isoscalar

nucleon), in the context of the two-Higgs doublet model Type II

(2HDM(II)). We discuss the contribution to the total cross-section of

diagrams, in which a charged Higgs boson is exchanged. We present

results which show strong dependence of such contributions on

$\tan\beta$ and $M_{H^{\pm}}$. We show that for $\tan\beta \approx

150$ and $M_{H^{\pm}}\approx 300$ GeV, the contribution of the

charged Higgs boson exchange diagrams to the cross-section of the

charged current inclusive $\nu_{\tau} {\cal N}$ collision can become

important. We find that this contribution for an inclusive dispersion

generated through the collision of an ultra-high-energy tau-neutrino

with $E_{\nu} \approx 10^{21}$ eV on a target nucleon can be as large

as 40\% of the value of the contribution of the $W^{\pm}$ exchange

diagrams, provided $M_{H^{\pm}} \approx 300$ GeV and $\tan\beta

\approx 150$. Such enhancement and the induced variation on the mean

inelasticity $\langle y \rangle^{\rm CC}$ could lead to sizeable

effects in the acceptance of cosmic tau-neutrino detectors at

experiments such as HiRes, PAO, and the CRTNT, which are anchored to

the ground, and at experiments such as EUSO and OWL, which are

proposed to orbit around the Earth. We also compare the contribution

to $\sigma^{\rm tot}_{H^+}$ from the different allowed initial quarks

and we show that the contribution from the bottom quark dominates by

far. This means that the $H^{\pm}$ contribution practically always

gives a top quark in the final state. Such a large component of the

cross-section having a top quark event in the final state could have

recognizable features in the EAS experiments.

Keywords. Charged Higgs bosons; ultra-high-energy neutrinos;

tau-neutrinos.

PACS Nos 13.15.+g; 13.85.Tp; 14.60.Fg; 14.80.Cp; 95.55.Vj