scholarly journals SCALAR DARK MATTER EFFECTS IN HIGGS AND TOP QUARK DECAYS

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2121-2129 ◽  
Author(s):  
XIAO-GANG HE ◽  
HO-CHIN TSAI ◽  
TONG LI ◽  
XUE-QIAN LI
Keyword(s):  
Dark Matter ◽  
Top Quark ◽  
Neutral Current ◽  
Higgs Doublet ◽  
Tree Level ◽  
Flavor Changing ◽  
Higgs Decay ◽  
Dark Matter Relic Density ◽  
Flavor Changing Neutral Current ◽  
Two Higgs Doublet Model

We study possible observational effects of scalar dark matter, the darkon D, in Higgs h and top quark t decay processes, h → DD and t → cDD in the minimal Standard Model (SM) and its two Higgs doublet model (THDM) extension supplemented with a SM singlet darkon scalar field D. We find that the darkon D can have a mass in the range of sub-GeV to several tens of GeV, interesting for LHC and ILC colliders, to produce the required dark matter relic density. In the SM with a darkon, t → cDD only occurs at loop level giving a very small rate, while the rate for Higgs decay h → DD can be large. In THDM III with a darkon, where tree level flavor changing neutral current (FCNC) interaction exists, a sizable rate for t → cDD is also possible.

scholarly journals DARK MATTER PAIR-PRODUCTION IN b → s TRANSITIONS

2006 ◽  
Vol 21 (06) ◽  
pp. 457-478 ◽  
Author(s):  
C. BIRD ◽  
R. KOWALEWSKI ◽  
M. POSPELOV
Keyword(s):  
Dark Matter ◽  
Parameter Space ◽  
B Mesons ◽  
Neutral Current ◽  
Missing Energy ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current ◽  
Generic Class ◽  
Current Transition ◽  
Matter Sector

The flavor-changing neutral current transition b → s can serve as a sensitive probe of WIMP dark matter models, if the WIMP mass is under 2 GeV. In this work we extend our earlier analysis to a generic class of models where the interaction between the dark matter sector and the Standard Model matter sector is mediated by the Higgs boson(s). We show that experimental limits on the decays of B-mesons to K(K*) and missing energy provide stringent constraints on the parameter space of such models, but do not rule out sub-GeV WIMPs in a model-independent way. We find that in the context of the NMSSM with light pseudoscalar Higgs, the WIMP masses under a few hundred MeV are generically excluded with the exception of few highly tuned points in the parameter space.

scholarly journals NEXT-TO-NEXT-TO-LEADING ORDER SOFT AND VIRTUAL CORRECTIONS FOR QCD, HIGGS AND SUSY PROCESSES

2004 ◽  
Vol 19 (06) ◽  
pp. 405-419 ◽  
Author(s):  
NIKOLAOS KIDONAKIS
Keyword(s):  
Top Quark ◽  
W Boson ◽  
Neutral Current ◽  
Leading Order ◽  
Large Transverse Momentum ◽  
Hadron Colliders ◽  
Unified Approach ◽  
Anomalous Couplings ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

We review recent advances in the calculation of higher-order soft-gluon corrections for a variety of QCD, Higgs, and SUSY processes in hadron colliders. A unified approach and master formulas for next-to-next-to-leading order soft and virtual corrections are discussed. We present some applications of the formalism to top quark pair production at the Tevatron and the LHC, top production via anomalous couplings in flavor-changing neutral-current processes, W boson hadroproduction at large transverse momentum, and charged Higgs production at the LHC.

Search for Flavor-Changing Neutral Current Decays of the Top Quark inpp¯Collisions ats=1.8TeV

1998 ◽  
Vol 80 (12) ◽  
pp. 2525-2530 ◽  
Author(s):  
F. Abe ◽  
H. Akimoto ◽  
A. Akopian ◽  
M. G. Albrow ◽  
S. R. Amendolia ◽  
...  
Keyword(s):  
Top Quark ◽  
Neutral Current ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

scholarly journals THE EXCLUSIVE $\bar B \to\pi e^+ e^-$ AND $\bar B\to \rho e^+ e^-$ DECAYS IN THE TWO HIGGS DOUBLET MODEL WITH FLAVOR CHANGING NEUTRAL CURRENTS

1999 ◽  
Vol 14 (27) ◽  
pp. 4365-4393 ◽  
Author(s):  
E. O. ILTAN
Keyword(s):  
Branching Ratio ◽  
Higgs Doublet ◽  
Branching Ratios ◽  
New Physics ◽  
Tree Level ◽  
Efficient Tool ◽  
Flavor Changing ◽  
The Matrix ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We present the leading logarithmic QCD corrections to the matrix element of the decay b→de+e- in the two Higgs doublet model with tree level flavor changing currents (model III). We continue studying the differential branching ratio and the CP-violating asymmetry for the exclusive decays B→πe+e- and B→ρe+e- and analysing the dependencies of these quantities on the selected model III parameters, ξU,D, including the leading logarithmic QCD corrections. Further, we present the forward–backward asymmetry of dileptons for the decay B→ρe+e- and discuss the dependencies to the model III parameters. We observe that there is a possibility to enhance the branching ratios and suppress the CP-violating effects for both decays in the framework of the model III. Therefore, the measurements of these quantities will be an efficient tool to search the new physics beyond the SM.

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