Search results for "STANDARD MODEL"
showing 10 items of 1206 documents
Lepton-flavour violation in hadronic tau decays and μ-τ conversion in nuclei
2021
Within the Standard Model Effective Field Theory framework, with operators up to dimension 6, we perform a model-independent analysis of the lepton-flavour-violating processes involving tau leptons. Namely, we study hadronic tau decays and $\ell$--$\tau$ conversion in nuclei, with $\ell = e,\mu$. Based on available experimental limits, we establish constraints on the Wilson coefficients of the operators contributing to these processes. Our work paves the way to extract the related information from Belle II and foreseen future experiments.
CP violation in decays of the lightest supersymmetric particle with bilinearly broken R parity
2002
Supersymmetric models with broken R-parity induced by lepton number violating terms provide a calculable framework for neutrino masses and mixings. Within models with bilinear R-parity breaking six new physical phases appear which are potential sources of novel CP-violating phenomena compared to the minimal supersymmetric extension of the standard model. We consider CP-violating observables in the decays of the lightest supersymmetric particle in this class of models. We show that: (i) Neutrino physics requires a strong correlation between three different pairs of phases, thus reducing the effective number of new phases to three. (ii) CP-violating phenomena in decays of the lightest supersy…
Dark matter and LHC phenomenology in a left-right supersymmetric model
2011
Left-right symmetric extensions of the Minimal Supersymmetric Standard Model can explain neutrino data and have potentially interesting phenomenology beyond that found in minimal SUSY seesaw models. Here we study a SUSY model in which the left-right symmetry is broken by triplets at a high scale, but significantly below the GUT scale. Sparticle spectra in this model differ from the usual constrained MSSM expectations and these changes affect the relic abundance of the lightest neutralino. We discuss changes for the standard stau (and stop) co-annihilation, the Higgs funnel and the focus point regions. The model has potentially large lepton flavour violation in both, left and right, scalar l…
Calculable inverse-seesaw neutrino masses in supersymmetry
2009
4 pages, 3 figures, 1 table.-- PACS numbers: 12.60.Jv; 11.30.Pb; 14.60.Pq; 95.35.+d 14.60.-z, 12.15.-y
Supersymmetric type-III seesaw mechanism: Lepton flavor violating decays and dark matter
2011
We study a supersymmetric version of the seesaw mechanism type III. The model consists of the minimal supersymmetric extension of the standard model particle content plus three copies of $\mathbf{24}$ superfields. The fermionic part of the $SU(2)$ triplet contained in the $\mathbf{24}$ is responsible for the type-III seesaw, which is used to explain the observed neutrino masses and mixings. Complete copies of $\mathbf{24}$ are introduced to maintain gauge coupling unification. These additional states change the beta functions of the gauge couplings above the seesaw scale. Using minimal Supergravity boundary conditions, we calculate the resulting supersymmetric mass spectra at the electrowea…
Discriminating between technicolor and warped extra dimensional model viapp→ZZchannel
2009
We explore the possibility to discriminate between certain strongly coupled technicolor (TC) models and warped extra dimensional models where the standard model fields are propagating in the extra dimension. We consider a generic QCD-like TC model with running coupling as well as two TC models with walking dynamics. We argue that, due to the different production mechanisms for the lowest-lying composite tensor state in these TC theories compared to the first Kaluza-Klein graviton mode of the warped extra dimensional case, it is possible to distinguish between these models based on the angular analysis of the reconstructed longitudinal $Z$ bosons in the $pp\ensuremath{\rightarrow}ZZ\ensurema…
Search for supersymmetry in di-photon final states at s=1.96 TeV
2008
We report results of a search for supersymmetry (SUSY) with gauge-mediated symmetry breaking in di-photon events collected by the DO experiment at the Fermilab Tevatron Collider in 2002-2006. In 1.1 fb(-1) of data, we find no significant excess beyond the background expected from the standard model and set the most stringent lower limits to date for a standard benchmark model on the lightest neutralino and chargino masses of 125 GeV and 229 GeV, respectively, at 95% confidence.
Minimal 3-loop neutrino mass models and charged lepton flavor violation
2020
We study charged lepton flavor violation for the three most popular 3-loop Majorana neutrino mass models. We call these models "minimal" since their particle content correspond to the minimal sets for which genuine 3-loop models can be constructed. In all the three minimal models the neutrino mass matrix is proportional to some powers of Standard Model lepton masses, providing additional suppression factors on top of the expected loop suppression. To correctly explain neutrino masses, therefore large Yukawa couplings are needed in these models. We calculate charged lepton flavor violating observables and find that the three minimal models survive the current constraints only in very narrow …
Precision on leptonic mixing parameters at future neutrino oscillation experiments
2012
Journal of High Energy Physics 2012.6 (2012): 73 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Present Status of b → sℓ + ℓ − Anomalies
2017
Abstract We discuss the observed deviations in b → s l + l − processes from the Standard Model predictions and present global fits for the New Physics description of these anomalies. We further investigate the stability of the global fits under different theoretical assumptions and suggest strategies and a number of observables to clear up the source of the anomalies.