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Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings
Clermont Université, France.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
2010 (English)In: Physical Review D - Particles, Fields, Gravitation and Cosmology, ISSN 1550-7998, Vol. 81, no 3, 035016- p.Article in journal (Refereed) Published
##### Abstract [en]

We consider constraints from flavor physics on two-Higgs-doublet models (2HDM) with general, flavor-diagonal, Yukawa couplings. Analyzing the charged Higgs contribution to different observables, we find that $b\to s\gamma$ transitions and $\Delta M_{B_d}$ restrict the coupling $\lambda_{tt}$ of the top quark (corresponding to $\cot\beta$ in models with a $Z_2$ symmetry) to $|\lambda_{tt}|<1$ for $m_{H^+}\lesssim 500$ GeV. Stringent constraints from $B$ meson decays are obtained also on the other third generation couplings $\lambda_{bb}$ and $\lambda_{\tau\tau}$, but with stronger dependence on $m_{H^+}$. For the second generation, we obtain constraints on combinations of $\lambda_{ss}$, $\lambda_{cc}$, and $\lambda_{\mu\mu}$ from leptonic $K$ and $D_s$ decays.The limits on the general couplings are translated to the common 2HDM types I -- IV with a $Z_2$ symmetry, and presented on the $(m_{H^+},\tan\beta)$ plane. The flavor constraints are most excluding in the type II model which lacks a decoupling limit in $\tan\beta$. We obtain a lower limit $m_{H^+}\gtrsim 300$ GeV in models of type II and III, while no lower bound on $m_{H^+}$ is found for types I and IV.

##### Place, publisher, year, edition, pages
2010. Vol. 81, no 3, 035016- p.
##### National Category
Physical Sciences
##### Identifiers
ISI: 000275069000077OAI: oai:DiVA.org:uu-111158DiVA: diva2:279547
Available from: 2009-12-04 Created: 2009-12-04 Last updated: 2010-12-22Bibliographically approved
##### In thesis
1. Physics at the High-Energy Frontier: Phenomenological Studies of Charged Higgs Bosons and Cosmic Neutrino Detection
Open this publication in new window or tab >>Physics at the High-Energy Frontier: Phenomenological Studies of Charged Higgs Bosons and Cosmic Neutrino Detection
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
##### Abstract [en]

The Standard Model of particle physics successfully describes present collider data. Nevertheless, theoretical and cosmological results call for its extension. A softly broken supersymmetric completion around the TeV scale solves several of the outstanding issues. Supersymmetry requires two Higgs doublets, leading to five physical Higgs states. These include a pair of charged Higgs bosons H±, which are a generic feature of theories with multiple Higgs doublets. Using results from high-energy colliders and flavour physics, constraints are derived on the charged Higgs boson mass and couplings; both for constrained scenarios in the minimal supersymmetric standard model (MSSM) with grand unification, and for general two-Higgs-doublet models. The MSSM results are compared to the projected reach for charged Higgs searches at the Large Hadron Collider (LHC). At the LHC, a light charged Higgs is accessible through top quark decay. Beyond a discovery, it is demonstrated how angular distributions sensitive to top quark spin correlations can be used to determine the structure of the H±tb coupling. The public code 2HDMC, which performs calculations in a general, CP-conserving, two-Higgs-doublet model, is introduced.

In parallel to the developments at colliders, the most energetic particles ever recorded are the ultra-high-energy (UHE) cosmic rays. To gain more insight into their origin, new experiments are searching for UHE neutrinos. These searches require detectors of vast volume, which can be achieved by searching for coherent radio pulses arising from the Askaryan effect. The prospects of using a satellite orbiting the Moon to search for neutrino interactions are investigated, and a similar study for an Earth-based radio telescope is presented. In both cases, the method is found competitive for detection of the very highest energy neutrinos considered.

##### Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 71 p.
##### Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 699
##### Keyword
particle physics, Standard Model, beyond the Standard Model, supersymmetry, Higgs physics, charged Higgs boson, LHC, flavour physics, ultra-high-energy neutrinos, Askaryan effect, radio detection, lunar satellites
##### National Category
Subatomic Physics
##### Research subject
High Energy Physics
##### Identifiers
urn:nbn:se:uu:diva-111162 (URN)978-91-554-7682-3 (ISBN)
##### Public defence
2010-01-29, Häggsalen, Ångströmlaboratoriet, Uppsala, 13:15 (English)
##### Supervisors
Available from: 2010-01-07 Created: 2009-12-04 Last updated: 2010-01-07Bibliographically approved

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