Top quark decay into charged Higgs boson in a general Two-Higgs-Doublet model: implications for the TEVATRON data

We analyze the unconventional top quark decay mode t -> H^+ b at the quantum level within the context of general Two-Higgs-Doublet models by including the full electroweak effects from the Yukawa couplings. The results are presented in the on-shell renormalization scheme with a physically well motivated definition of tan(beta). While the QCD corrections have been taken into account in the current experimental analyses of that decay, the electroweak effects have always been neglected. However, we find that they can be rather large and could dramatically alter the interpretation of the present data from the Tevatron collider. For instance, in large portions of the parameter space the electroweak effects prevent the Tevatron data from placing any bound at all to the charged Higgs mass for essentially any value of tan(beta).Comment: 11 pages, LaTeX, 4 figs included using epsfi

Production and FCNC decay of supersymmetric Higgs bosons into heavy quarks in the LHC

We analyze the production and subsequent decay of the neutral MSSM Higgs bosons (h = h^0, H^0, A^0) mediated by flavor changing neutral currents (FCNC) in the LHC collider. We have computed the h-production cross-section times the FCNC branching ratio, \sigma(pp -> h -> qq') = \sigma(pp -> h) B(h -> qq'), in the LHC focusing on the strongly-interacting FCNC sector. Here qq' is an electrically neutral pair of quarks of different flavors, the dominant modes being those containing a heavy quark: tc or bs. We determine the maximum production rates for each of these modes and identify the relevant regions of the MSSM parameter space, after taking into account the severe restrictions imposed by low energy FCNC processes. The analysis of \sigma(pp -> h -> qq') singles out regions of the MSSM parameter space different from those obtained by maximizing only the branching ratio, due to non-trivial correlations between the parameters that maximize/minimize each isolated factor. The production rates for the bs channel can be huge for a FCNC process (0.1-1 pb), but its detection can be problematic. The production rates for the tc channel are more modest (10^{-3}-10^{-2} pb), but its detection should be easier due to the clear-cut top quark signature. A few thousand tc events could be collected in the highest luminosity phase of the LHC, with no counterpart in the SM.Comment: 25 pages, 9 figures, 2 tables, LaTeX 2e. Typos corrected. Version to appear in JHE

The tan(beta) - M_H^\pm bound from inclusive semi-tauonic B-decays in the MSSM

We compute the O(alpha_s) SUSY-QCD corrections to the W and charged Higgs mediated inclusive semi-tauonic B-decay, B->tau antineutrino_tau X. Combining the SUSY contribution with the SM result obtained from the heavy quark effective field theory, plus ordinary QCD corrections, we find that the allowed region in the (tan(beta),M_H^\pm)-plane could be significantly modified by the short-distance supersymmetric effects. Since the sensitivity to the SUSY parameters other than mu (the higgsino mixing mass) is rather low, the following effective bound emerges for mu<0 at the 2 sigma level: tan(beta)~< 0.43 (M_H^\pm/GeV). Remarkably, for mu>0 there could be no bound at all. Finally, we provide a combined (tan(beta,M_H^\pm) exclusion plot using our B-meson results together with the recent data from top quark decays.Comment: 15 pages, LaTeX, 1 table and 3 figs included as a separate file, full postscript version avaliable at ftp://ftp.ifae.es/preprint/ft/uabft407.ps . New comments and references added. Accepted version in Phys. Lett.

Higgs triplet effects in purely leptonic processes

We consider the effect of complex Higgs triplets on purely leptonic processes and survey the experimental constraints on the mass and couplings of their single and double charge members. Present day experiments tolerate values of the Yukawa couplings of these scalars at the level of the standard electroweak gauge couplings. We show that the proposed measurement of the ratio R_{LCD}=\sigma (\nu_{\mu}e)/ [\sigma (\bb\nu_{\mu}e) + \sigma (\nu_e e )] would allow to explore a large region of the parameter space inaccessible to the usual ratio R=\sigma (\nu_{\mu}e)/\sigma (\bb\nu_{\mu}e).Comment: 14 pages, LaTeX, Three figures included using uufiles. A postscript version is available at ftp://ftp.ifae.es/preprint/ft/uabft378.p

Loop effects and non-decoupling property of SUSY QCD in gb→tH−g b\to tH^{-}

One-loop SUSY QCD radiative correction to $gb \to tH^{-}$ cross section is calculated in the Minimal Supersymmetric Standard Model. We found that SUSY QCD is non-decoupling if the gluino mass and the parameter $\mu$, $A_t$ or $A_b$ are at the same order and get large. The non-decoupling contribution can be enhanced by large $\tan\beta$ and therefore large corrections to the hadronic production rates at the Tevatron and LHC are expected in the large $\tan\beta$ limit. The fundamental reason for such non-decoupling behavior is found to be some couplings in the loops being proportional to SUSY mass parameters.Comment: 15 pages, 5 PS figures. A proof of non-decouplings of SUSY-QCD, Comments on corresponding QCD correction and references adde

Study of the cosmogenic activation in NaI(Tl) crystals within the ANAIS experiment

The direct detection of galactic dark matter particles requires ultra-low background conditions. NaI(Tl) crystals are applied in the search for these dark matter particles through their interactions in the detector by measuring the scintillation signal produced. The production of long-lived isotopes in materials due to the exposure to cosmic rays on Earth''s surface can be an hazard for these ultra-low background demanding experiments, typically performed underground. Therefore, production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well-known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Here, analysis of the cosmogenic studies developed from the ANAIS experiment NaI(Tl) detectors are presented. Installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays and thanks to the prompt data taking developed, identification and quantification of isotopes with half-lives of the order of tens of days were allowed, and thanks to the long-term operation of the detectors long-lived isotopes have been also identified and quantified. Main results for the activation yields of iodine and tellurium isotopes, 22Na, 113Sn, 109Cd, and tritium are presented in this work, together with the estimate of the production rates for their activation by cosmic nucleons while on Earth''s surface based on a selection of excitation functions over the entire energy range of cosmic nucleons

Cosmogenic and primordial radioisotopes in copper bricks shortly exposed to cosmic rays

Cosmogenic activation is the most common source of radioactivity in copper, being 60 Co the most significant because of its long half-life (5.27 y) and saturation activity at sea level of 1 mBq/kg. Copper bricks, which had been exposed to cosmic rays for 41 days after their casting, were used to replace the internal 10 cm of the lead shielding of a HPGe detector placed at the Canfranc Underground Laboratory. We describe the outcome of the new shielding and the cosmogenic and primordial radioisotopes observed

The ANAIS-112 experiment at the Canfranc Underground Laboratory

The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal at the Canfranc Underground Laboratory (LSC). Several 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc. have been operated there during the last years in various set-ups; an outstanding light collection at the level of 15 photoelectrons per keV, which allows triggering at 1 keV of visible energy, has been measured for all of them and a complete characterization of their background has been achieved. In the first months of 2017, the full ANAIS-112 set-up consisting of nine Alpha Spectra detectors with a total mass of 112.5 kg was commissioned at LSC and the first dark matter run started in August, 2017. Here, the latest results on the detectors performance and measured background from the commissioning run will be presented and the sensitivity prospects of the ANAIS-112 experiment will be discussed

First Results on Dark Matter Annual Modulation from the ANAIS-112 Experiment

ANAIS is a direct detection dark matter experiment aiming at the testing of the DAMA/LIBRA annual modulation result, which, for about two decades, has neither been confirmed nor ruled out by any other experiment in a model independent way. ANAIS - 112, consisting of 112.5 kg of sodium iodide crystals, has been taking data at the Canfranc Underground Laboratory, Spain, since August 2017. This Letter presents the annual modulation analysis of 1.5 years of data, amounting to 157.55 kg yr. We focus on the model independent analysis searching for modulation and the validation of our sensitivity prospects. ANAIS - 112 data are consistent with the null hypothesis (p values of 0.67 and 0.18 for [2-6] and [1-6] keV energy regions, respectively). The best fits for the modulation hypothesis are consistent with the absence of modulation (S-m = -0.0044 +/- 0.0058 cpd/kg/keV and -0.0015 +/- 0.0063 cpd/kg/keV, respectively). They are in agreement with our estimated sensitivity for the accumulated exposure, which supports our projected goal of reaching a 3 sigma sensitivity to the DAMA/LIBRA result in five years of data taking

Prospects for heavy supersymmetric charged Higgs boson searches at hadron colliders

We investigate the production of a heavy charged Higgs boson at hadron colliders within the context of the MSSM. A detailed study is performed for all important production modes and basic background processes for the t\bar{t}b\bar{b} signature. In our analysis we include effects of initial and final state showering, hadronization, and principal detector effects. For the signal production rate we include the leading SUSY quantum effects at high \tan\beta>~ mt/mb. Based on the obtained efficiencies for the signal and background we estimate the discovery and exclusion mass limits of the charged Higgs boson at high values of \tan\beta. At the upgraded Tevatron the discovery of a heavy charged Higgs boson (MH^+ >~ 200 GeV) is impossible for the tree-level cross-section values. However, if QCD and SUSY effects happen to reinforce mutually, there are indeed regions of the MSSM parameter space which could provide 3\sigma evidence and, at best, 5\sigma charged Higgs boson discovery at the Tevatron for masses M_H^+<~ 300 GeV and M_H^+<~ 250 GeV, respectively, even assuming squark and gluino masses in the (500-1000) GeV range. On the other hand, at the LHC one can discover a H^+ as heavy as 1 TeV at the canonical confidence level of 5\sigma; or else exclude its existence at 95% C.L. up to masses ~ 1.5 TeV. Again the presence of SUSY quantum effects can be very important here as they may shift the LHC limits by a few hundred GeV.Comment: Latex2e, 44 pages, 15 figures, 6 tables, uses JHEP3.sty, axodraw.sty. Comments added. Discussion on QCD factors clarified. Added discussion on uncertainties. Change of presentation of Tables 4 and 5 and Fig.6. Results and conclusions unchanged. Version accepted in JHE