56 research outputs found
Yukawa couplings and seesaw neutrino masses in noncommutative gauge theory
We consider Yukawa couplings in a theta-exact approach to noncommutative
gauge field theory and show that both Dirac and singlet Majorana neutrino mass
terms can be consistently accommodated. This shows that in fact the whole
neutrino-mass extended standard model on noncommutative spacetime can the
formulated in the new nonperturbative (in theta) approach which eliminates the
previous restriction of Seiberg-Witten map based theories to low-energy
phenomena. Spacetime noncommutativity induced couplings between neutrinos and
photons as well as Z-bosons appear quite naturally in the model. We derive
relevant Feynman rules for the type I seesaw mechanism.Comment: 10 pages, version to be published in Physics Letters
Radiative Seesaw in SO(10) with Dark Matter
High energy accelerators may probe into dark matter and the seesaw neutrino
mass scales if they are not much heavier than ~O(TeV). In the absence of
supersymmetry, we extend a class of SO(10) models to predict well known cold
dark matter candidates while achieving precision unification with
experimentally testable proton lifetime. The most important prediction is a new
radiative seesaw formula of Ma type accessible to accelerator tests while the
essential small value of its quartic coupling also emerges naturally. This
dominates over the high-scale seesaw contributions making a major impact on
neutrino physics and dark matter, opening up high prospects as a theory of
fermion masses.Comment: 11 pages LaTex, no figures.hep-ph, astro-ph, hep-th; Version accepted
in Phys. Lett.
TeV Scale Leptogenesis, theta_13 And Doubly Charged Particles At LHC
We explore a realistic supersymmetric SU(2)_L \times SU(2)_R \times U(1)_B-L
model spontaneously broken at around 10^12 GeV. The presence of D and F-flat
directions gives rise to TeV mass doubly charged particles which can be found
at the LHC. We implement TeV scale leptogenesis and employing both type I and
II seesaw, the three light neutrinos are partially degenerate with masses in
the 0.02-0.1 eV range. The effective mass parameter for neutrinoless double
beta decay is 0.03-0.05 eV. We also find the interesting relation tan 2
\theta_13 ~ [\Delta m^2_{\odot} / \Delta m^2_{atm}] [sin 2 \theta_12 /tan 2
\theta_23] <~ 0.02.Comment: 18 pages, 4 figures, revtex4. v2: minor changes, matches published
versio
Mass predictions based on a supersymmetric SU(5) fixed point
I examine the possibility that the third generation fermion masses are
determined by an exact fixed point of the minimal supersymmetric SU(5) model.
When one-loop supersymmetric thresholds are included, this unified fixed point
successfully predicts the top quark mass, 175 +(-) 2 GeV, as well as the weak
mixing angle. The bottom quark mass prediction is sensitive to the
supersymmetric thresholds; it approaches the measured value for mu <0 and very
large unified gaugino mass. The experimental measurement of the tau lepton mass
determines tan(beta), and the strong gauge coupling and fine structure constant
fix the unification scale and the unified gauge coupling.Comment: 40 pages, 9 figures, 9 tables, Revtex
Beyond the standard seesaw: neutrino masses from Kahler operators and broken supersymmetry
We investigate supersymmetric scenarios in which neutrino masses are
generated by effective d=6 operators in the Kahler potential, rather than by
the standard d=5 superpotential operator. First, we discuss some general
features of such effective operators, also including SUSY-breaking insertions,
and compute the relevant renormalization group equations. Contributions to
neutrino masses arise at low energy both at the tree level and through finite
threshold corrections. In the second part we present simple explicit
realizations in which those Kahler operators arise by integrating out heavy
SU(2)_W triplets, as in the type II seesaw. Distinct scenarios emerge,
depending on the mechanism and the scale of SUSY-breaking mediation. In
particular, we propose an appealing and economical picture in which the heavy
seesaw mediators are also messengers of SUSY breaking. In this case, strong
correlations exist among neutrino parameters, sparticle and Higgs masses, as
well as lepton flavour violating processes. Hence, this scenario can be tested
at high-energy colliders, such as the LHC, and at lower energy experiments that
measure neutrino parameters or search for rare lepton decays.Comment: LaTeX, 34 pages; some corrections in Section
Decoupling property of the supersymmetric Higgs sector with four doublets
In supersymmetric standard models with multi Higgs doublet fields,
selfcoupling constants in the Higgs potential come only from the D-terms at the
tree level. We investigate the decoupling property of additional two heavier
Higgs doublet fields in the supersymmetric standard model with four Higgs
doublets. In particular, we study how they can modify the predictions on the
quantities well predicted in the minimal supersymmetric standard model (MSSM),
when the extra doublet fields are rather heavy to be measured at collider
experiments. The B-term mixing between these extra heavy Higgs bosons and the
relatively light MSSM-like Higgs bosons can significantly change the
predictions in the MSSM such as on the masses of MSSM-like Higgs bosons as well
as the mixing angle for the two light CP-even scalar states. We first give
formulae for deviations in the observables of the MSSM in the decoupling region
for the extra two doublet fields. We then examine possible deviations in the
Higgs sector numerically, and discuss their phenomenological implications.Comment: 26 pages, 24 figures, text sligtly modified,version to appear in
Journal of High Energy Physic
Systematic study of the d=5 Weinberg operator at one-loop order
We perform a systematic study of the Weinberg operator at the one-loop
level. We identify three different categories of neutrino mass generation: (1)
finite irreducible diagrams; (2) finite extensions of the usual seesaw
mechanisms at one-loop and (3) divergent loop realizations of the seesaws. All
radiative one-loop neutrino mass models must fall into one of these classes.
Case (1) gives the leading contribution to neutrino mass naturally and a
classic example of this class is the Zee model. We demonstrate that in order to
prevent that a tree level contribution dominates in case (2), Majorana fermions
running in the loop and an additional symmetry are needed for a
genuinely leading one-loop contribution. In the type-II loop extensions, the
lepton number violating coupling will be generated at one loop, whereas the
type-I/III extensions can be interpreted as loop-induced inverse or linear
seesaw mechanisms. For the divergent diagrams in category (3), the tree level
contribution cannot be avoided and is in fact needed as counter term to absorb
the divergence.Comment: 18 pages, 5 Figures, 4 Tables - Version to appear in JHE
125 GeV Higgs Boson from t-b-tau Yukawa Unification
We identify a class of supersymmetric SU(4)_c x SU(2)_L x SU(2)_R models in
which imposing essentially perfect t-b-tau Yukawa coupling unification at M_GUT
yields a mass close to 122-126 GeV for the lightest CP-even (SM-like) Higgs
boson. The squark and gluino masses in these models exceed 3 TeV, but the stau
and charginos in some cases can be considerably lighter. We display some
benchmark points corresponding to neutralino-stau and bino-wino coannihilations
as well as A-resonance. The well-known MSSM parameter tan beta is around 46-52.Comment: 16 pages, 4 figure
Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science
Search for heavy lepton partners of neutrinos in proton-proton collisions in the context of the type III seesaw mechanism
This is the Pre-print version of the Article. The official publishe version can be accessed from the link below - Copyright @ 2012 ElsevierA search is presented in protonâproton collisions at sqrt(s) = 7TeV for fermionic triplet states expected in type III seesaw models. The search is performed using final states with three isolated charged leptons and an imbalance in transverse momentum. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 4.9 fbâ1. No excess of events is observed above the background predicted by the standard model, and the results are interpreted in terms of limits on production cross sections and masses of the heavy partners of the neutrinos in type III seesaw models. Depending on the considered scenarios, lower limits are obtained on the mass of the heavy partner of the neutrino that range from 180 to 210 GeV. These are the first limits on the production of type III seesaw fermionic triplet states reported by an experiment at the LHC.This study is spported by the BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie
programme and the European Research Council (European Union); the Leventis Foundation;
the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal
Science Policy Office; the Fonds pour la Formation a la Recherche dans lâIndustrie et dans lâAgriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); and the HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
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