Search results for "BREAKING"
showing 10 items of 383 documents
Two-Body Decays of the Lightest Stop in Supergravity with and without R-Parity
1999
We study the decays of the lightest top squark in supergravity models with and without R-parity. Using the simplest model with an effective explicit bilinear breaking of R-parity and radiative electroweak symmetry breaking we show that, below the threshold for decays into charginos $\tilde t_1\to c\chi^+_1$, the lightest stop decays mainly into third generation fermions, $\tilde t_1\to b\tau$ instead of the R-parity conserving mode $\tilde t_1\to c\chi^0_1$, even for tiny tau--neutrino mass values. Moreover we show that, even above the threshold for decays into charginos, the decay $\tilde t_1\to b\tau$ may be dominant. We study the role played by the universality of the boundary conditions…
Minimal supergravity radiative effects on the tri-bimaximal neutrino mixing pattern
2007
7 pages, 3 figures.-- PACS nrs.: 14.60.Pq, 12.60.Jv.-- ISI Article Identifier: 000245333000012.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0606082
Supersymmetric Unification with Radiative Breaking of R-parity
1996
We show how R-parity can break spontaneously as a result of radiative corrections in unified N=1 supergravity models. We illustrate this with a concrete rank-four unified model, where the spontaneous breaking of R-parity is accompanied by the existence of a physical majoron. We determine the resulting supersymmetric particle mass spectrum and show that R-parity-breaking signals may be detectable at LEP200.
Unification of gauge couplings and the tau-neutrino mass in supergravity without R parity
1999
Minimal R-parity violating supergravity predicts a value for $alpha_s(M_Z)$ smaller than in the case with conserved R-parity, and therefore closer to the experimental world average. We show that the R-parity violating effect on the $alpha_s$ prediction comes from the larger two-loop b-quark Yukawa contribution to the renormalization group evolution of the gauge couplings which characterizes R-parity violating supergravity. The effect is correlated to the tau neutrino mass and is sensitive to the initial conditions on the soft supersymmetry breaking parameters at the unification scale. We show how a few percent effect on $alpha_s(M_Z)$ may naturally occur even with tau neutrino masses as sma…
ON THE STABILITY OF SUPERSYMMETRY IN CURVED SPACE-TIME
1990
We discuss the stability of the classical supergravity background in a simple supersymmetric model at the quantum level, showing that two different pictures emerge depending on whether the emphasis is placed on the conformal invariance or on the supersymmetry invariance of the theory.
Supersymmetry in the standard model of electroweak interactions
1993
Abstract Starting from the peculiar chirality pattern of weak and electromagnetic interactions, established by experiment, we show that the minimal standard model contains supersymmetry, though in a new, unconventional, realization. It appears as an action on the fields but is not an invariance of the lagrangian. This supersymmetry which is not in conflict with experiment, is seen to be the raison d'etre of the Higgs fields and provides a geometrical understanding of spontaneous symmetry breaking. It turns out that this approach which is based on the fundamental role of left- and right-chiral spinor fields in weak interactions, has many similarities to models developed in the framework of n…
Isospin-breaking corrections to superallowed Fermi beta-decay in isospin- and angular momentum-projected nuclear Density Functional Theory
2012
Background: The superallowed beta-decay rates provide stringent constraints on physics beyond the Standard Model of particle physics. To extract crucial information about the electroweak force, small isospin-breaking corrections to the Fermi matrix element of superallowed transitions must be applied. Purpose: We perform systematic calculations of isospin-breaking corrections to superallowed beta-decays and estimate theoretical uncertainties related to the basis truncation, time-odd polarization effects related to the intrinsic symmetry of the underlying Slater determinants, and to the functional parametrization. Methods: We use the self-consistent isospin- and angular-momentum-projected nuc…
Isospin dependence of the three-nucleon force
2004
We classify $A$--nucleon forces according to their isospin dependence and discuss the most general isospin structure of the three--nucleon force. We derive the leading and subleading isospin--breaking corrections to the three--nucleon force using the framework of chiral effective field theory.
125 GeV Higgs from a chiral techniquark model
2014
We consider the spin-zero spectrum of a strongly coupled gauge theory. In particular, we focus on the dynamical mass of the isosinglet scalar resonance in the presence of a four-fermion interaction external to the gauge dynamics. This is motivated by the extended technicolor framework for dynamical electroweak symmetry breaking. Applying the large-$N$ limit, we sum all the leading-order contributions, and find that the corrections to the mass of the isosinglet scalar resonance can be large, potentially reducing its value from ${\cal O}(1)$ TeV to the observed value of 125 GeV.
Ground-state binding energy of HΛ4 from high-resolution decay-pion spectroscopy
2016
Abstract A systematic study on the Λ ground state binding energy of hyperhydrogen H Λ 4 measured at the Mainz Microtron MAMI is presented. The energy was deduced from the spectroscopy of mono-energetic pions from the two-body decays of hyperfragments, which were produced and stopped in a 9Be target. First data, taken in the year 2012 with a high resolution magnetic spectrometer, demonstrated an almost one order of magnitude higher precision than emulsion data, while being limited by systematic uncertainties. In 2014 an extended measurement campaign was performed with improved control over systematic effects, increasing the yield of hypernuclei and confirming the observation with two indepen…