Production of doubly charged scalars from the decay of singly charged scalars in the Higgs Triplet Model

The existence of doubly charged Higgs bosons (H^{\pm\pm}) is a distinctive feature of the Higgs Triplet Model (HTM), in which neutrinos obtain tree-level masses from the vacuum expectation value of a neutral scalar in a triplet representation of SU(2)_L. We point out that a large branching ratio for the decay of a singly charged Higgs boson to a doubly charged Higgs boson via H^\pm\to H^{\pm\pm}W^* is possible in a sizeable parameter space of the HTM. From the production mechanism q'qbar\to W^* \to H^{\pm\pm}H^\mp the above decay mode would give rise to pair production of H^{\pm\pm}, with a cross section which can be comparable to that of the standard pair-production mechanism qqbar\to \gamma^*,Z^* \to H^{++}H^{--}. We suggest that the presence of a sizeable branching ratio for H^\pm\to H^{\pm\pm}W^* could significantly enhance the detection prospects of H^{\pm\pm} in the four-lepton channel. Moreover, the decays H^0\to H^\pm W^* and A^0\to H^\pm W^* from production of the neutral triplet scalars H^0 and A^0 would also provide an additional source of H^\pm, which can subsequently decay to H^{\pm\pm}.Comment: 13 pages, 3 figures, two figures added in v2, to appear in Physical Review

Single and Pair Production of Doubly Charged Higgs Bosons at Hadron Colliders

Current searches for doubly charged Higgs bosons (H^{\pm\pm}) at the Fermilab Tevatron are sensitive to single production of H^{\pm\pm}, although the pair production mechanism q\bar q\to H^{++}H^{--} is assumed to be dominant. In the context of a Higgs Triplet Model we study the mechanism q'\bar q\to H^{\pm\pm}H^{\mp} at the Tevatron and CERN Large Hadron Collider, and show that its inclusion can significantly improve the search potential for H^{\pm\pm}. Moreover, assuming that the neutrino mass is generated solely by the triplet field Yukawa coupling to leptons, we compare the branching ratios of H^{\pm\pm}\to l^\pm l^\pm and H^{\pm\pm}\to H^\pm W^* for the cases of a normal hierarchical, inverted hierarchical and degenerate neutrino mass spectrum.Comment: 17 pages, 15 figures, references added, version to appear in PR

Searching for a light Fermiophobic Higgs Boson at the Tevatron

We propose new production mechanisms for light fermiophobic Higgs bosons ($h_f$) with suppressed couplings to vector bosons ($V$) at the Fermilab Tevatron. These mechanisms (e.g. $qq'\to H^\pm h_f$) are complementary to the conventional process $qq'\to Vh_f$, which suffers from a strong suppression of $1/\tan^2\beta$ in realistic models with a $h_f$. The new mechanisms extend the coverage at the Tevatron Run II to the larger $\tan\beta$ region, and offer the possibility of observing new event topologies with up to 4 photons.Comment: 15 pages, including 5 eps-figure

Charged Higgs bosons in the Next-to MSSM (NMSSM)

The charged Higgs boson decays $H^\pm\to W^\pm A_1$ and $H^\pm\to W^\pm h_i$ are studied in the framework of the next-to Minimal Supersymmetric Standard Model (NMSSM). It is found that the decay rate for $H^\pm\to W^\pm A_1$ can exceed the rates for the $\tau^\pm\nu$ and $tb$ channels both below and above the top-bottom threshold. The dominance of $H^\pm\to W^\pm A_1$ is most readily achieved when $A_1$ has a large doublet component and small mass. We also study the production process $pp\to H^\pm A_1$ at the LHC followed by the decay $H^\pm\to W^\pm A_1$ which leads to the signature $W^\pm A_1 A_1$. We suggest that $p p\to H^\pm A_1$ is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate $\tan\beta$ and dominant decay mode $H^\pm \to W^\pm A_1$. This $W^\pm A_1 A_1$ signature can also arise from the Higgsstrahlung process $pp\to W^\pm h_1$ followed by the decay $h_1\to A_1 A_1$. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.Comment: 20 pages, 22 eps figures, more reference adde

Constraints on the Universal Varying Yukawa Couplings: from SM-like to Fermiophobic

Varying the Standard Model (SM) fermion Yukawa couplings universally by a generic positive scale factor ($F_{Yu}$), we study the phenomenological fit to the current available experimental results for the Higgs boson search at hadron colliders. We point out that the Higgs production cross section and its decay branching ratio to $\gamma\gamma$ can be varied oppositely by $F_{Yu}$ to make their product almost invariant. Thus, our scenario and the SM Higgs are indistinguishable in the inclusive $H\to \gamma\gamma$ channel. The current measurements on direct Yukawa coupling strength in the $H\to b\bar{b}/\tau\tau$ channel are not precise enough to fix the scale factor $F_{Yu}$. The most promising is the vector-boson-fusion channel in which the CMS has already observed possible suppression effect on the Yukawa couplings. Further more, the global $\chi^2$ fit of the experimental data can get the optimal value by introducing a suppression factor $F_{Yu}\sim1/2$ on the SM Yukawa couplings.Comment: 16 pages, 12 figures, 5 tables, update analysis is supplemente

Tree-unitarity bounds for THDM Higgs masses revisited

We have reconsidered theoretical upper bounds on the scalar boson masses within the two-Higgs-doublet model (THDM), employing the well-known technical condition of tree-level unitarity. Our treatment provides a modest extension and generalization of some previous results of other authors. We present a rather detailed discussion of the solution of the relevant inequalities and offer some new analytic formulae as well as numerical values for the Higgs mass bounds in question. A comparison is made with the earlier results on the subject that can be found in the literature.Comment: 20 pages, 6 figures; correction to typos; will appear in Eur. Phys. J.

Effect of Charged Scalar Loops on Photonic Decays of a Fermiophobic Higgs

Higgs bosons with very suppressed couplings to fermions ("Fermiophobic Higgs bosons", h_f) can decay to two photons (\gamma\gamma) with a branching ratio significantly larger than that expected for the Standard Model Higgs boson for m_{h_f}<150 GeV. Such a particle would give a clear signal at the LHC and can arise in the Two Higgs Doublet Model (type I) in which h_f -> \gamma\gamma is mediated by W^+ and charged Higgs boson (H^+) loops. We show that the H^+ loops can cause both constructive and destructive contributions with a magnitude considerably larger than the anticipated precision in the measurement of the photonic decay channel at future hadron and lepton colliders.Comment: 18 pages, 5 figures, clarifications added, one reference added, accepted by Physical Review

Health and Medical Researcher Publishing Patterns and How Libraries Support Them

Changing business models in scholarly publishing means that researchers have increased choices as to where to submit their articles. Choices are made on the basis of perceived quality of the journal, the speed of publishing, and how close a match there is between the journal scope and the article topic. Additionally, there is an increasing concern as to whether the journals are predatory. This paper reports on a study which sought to understand how health researchers go about selecting where to publish and the support that they receive in this regard from librarians and related staff. The research confirms that knowledge of a specific journal is still the predominant factor for researchers and that they prefer to rely on their own judgment. Librarians are providing the tools such as databases and whitelists by which better choices can be made whilst exploring new roles in advising and training researchers. Predatory journals are being selected by some, chiefly as a consequence of a lack of awareness amongst researchers and the need for some to publish swiftly and at low cost

Charged Higgs boson contribution to νˉe−e\bar{\nu}_e-e scattering from low to ultrahigh energy in Higgs triplet model

We study the $\bar{\nu}_e-e$ scattering from low to ultrahigh energy in the framework of Higgs Triplet Model (HTM). We add the contribution of charged Higgs boson exchange to the total cross section of the scattering. We obtain the upper bound $h_{ee}/M_{H^\pm}\lesssim2.8\times10^{-3}GeV^{-1}$ in this process from low energy experiment. We show that by using the upper bound obtained, the charged Higgs contribution can give enhancements to the total cross section with respect to the SM prediction up to 5.16% at $E\leq10^{14}$ eV and maximum at $s\approx M_{H^\pm}^2$ and would help to determine the feasibility experiments to discriminate between SM and HTM at current available facilities.Comment: 6 pages, 6 figure