7 research outputs found
An origin for small neutrino masses in the NMSSM
We consider the Next to Minimal Supersymmetric Standard Model (NMSSM) which
provides a natural solution to the so-called mu problem by introducing a new
gauge-singlet superfield S. We realize that a new mechanism of neutrino mass
suppression, based on the R-parity violating bilinear terms mu_i L_i H_u mixing
neutrinos and higgsinos, arises within the NMSSM, offering thus an original
solution to the neutrino mass problem (connected to the solution for the mu
problem). We generate realistic (Majorana) neutrino mass values without
requiring any strong hierarchy amongst the fundamental parameters, in contrast
with the alternative models. In particular, the ratio |mu_i/mu| can reach about
10^-1, unlike in the MSSM where it has to be much smaller than unity. We check
that the obtained parameters also satisfy the collider constraints and internal
consistencies of the NMSSM. The price to pay for this new cancellation-type
mechanism of neutrino mass reduction is a certain fine tuning, which get
significantly improved in some regions of parameter space. Besides, we discuss
the feasibility of our scenario when the R-parity violating bilinear terms have
a common origin with the mu term, namely when those are generated via a VEV of
the S scalar component from the couplings lambda_i S L_i H_u. Finally, we make
comments on some specific phenomenology of the NMSSM in the presence of
R-parity violating bilinear terms.Comment: 21 pages, 5 figures, Latex fil
Novel signatures for vector-like quarks
We consider supersymmetric extensions of the standard model with a vector-like doublet (T B) of quarks with charge 2/3 and −1/3, respectively. Compared to non-supersymmetric models, there is a variety of new decay modes for the vector-like quarks, involving the extra scalars present in supersymmetry. The importance of these new modes, yielding multi-top, multi-bottom and also multi-Higgs signals, is highlighted by the analysis of several benchmark scenarios. We show how the triangles commonly used to represent the branching ratios of the ‘standard’ decay modes of the vector-like quarks involving W, Z or Higgs bosons can be generalised to include additional channels. We give an example by recasting the limits of a recent heavy quark search for this more general case.The work of J.A. Aguilar-Saavedra has been supported by MINECO Projects FPA 2016-
78220-C3-1-P and FPA 2013-47836-C3-2-P (including ERDF), and by Junta de Andaluc a
Project FQM-101. The work of D.E. L opez-Fogliani has been supported by the Argentinian
CONICET. The work of C. Mu~noz has been supported in part by the Programme SEV-
2012-0249 `Centro de Excelencia Severo Ochoa'. D.E. L opez-Fogliani and C. Mu~noz also
acknowledge the support of the Spanish grant FPA2015-65929-P (MINECO/FEDER, UE),
and MINECO's Consolider-Ingenio 2010 Programme under grant MultiDark CSD2009-
00064
Theoretical predictions for the direct detection of neutralino dark matter in the NMSSM
We analyse the direct detection of neutralino dark matter in the framework of
the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed
analysis of the parameter space, taking into account all the available
constraints from LEPII, we compute the neutralino-nucleon cross section, and
compare the results with the sensitivity of detectors. We find that sizable
values for the detection cross section, within the reach of dark matter
detectors, are attainable in this framework. For example, neutralino-proton
cross sections compatible with the sensitivity of present experiments can be
obtained due to the exchange of very light Higgses with m_{h_1^0}\lsim 70
GeV. Such Higgses have a significant singlet composition, thus escaping
detection and being in agreement with accelerator data. The lightest neutralino
in these cases exhibits a large singlino-Higgsino composition, and a mass in
the range 50\lsim m_{\tilde\chi_1^0}\lsim 100 GeV.Comment: Final version to appear in JHEP. References added. LaTeX, 53 pages,
23 figure
Collider aspects of flavour physics at high Q
This review presents flavour related issues in the production and decays of
heavy states at LHC, both from the experimental side and from the theoretical
side. We review top quark physics and discuss flavour aspects of several
extensions of the Standard Model, such as supersymmetry, little Higgs model or
models with extra dimensions. This includes discovery aspects as well as
measurement of several properties of these heavy states. We also present public
available computational tools related to this topic.Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era
of the LHC'', Geneva, Switzerland, November 2005 -- March 200
Theoretical predictions for the direct detection of neutralino dark matter in the NMSSM
We analyse the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed analysis of the parameter space, taking into account all the available constraints from LEPII, we compute the neutralino-nucleon cross section, and compare the results with the sensitivity of detectors. We find that sizable values for the detection cross section, within the reach of dark matter detectors, are attainable in this framework. For example, neutralino-proton cross sections compatible with the sensitivity of present experiments can be obtained due to the exchange of very light Higgses with m_h__1_"0 <- 70 GeV. Such Higgses have a significant singlet composition, thus escaping detection and being in agreement with accelerator data. The lightest neutralino in these cases exhibits a large singlino-Higgsino composition, and a mass in the range 50 <-m_x__1_"0 <- 100 GeV. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(04-129) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman