Search results for "weak interaction"
showing 10 items of 431 documents
Minimal supergravity with R-parity breaking
1997
We show that the minimal R-parity breaking model characterized by an effective bilinear violation of R-parity in the superpotential is consistent with minimal N=1 supergravity unification with radiative breaking of the electroweak symmetry and universal scalar and gaugino masses. This one-parameter extension of the MSSM-SUGRA model provides therefore the simplest reference model for the breaking of R-parity and constitutes a consistent truncation of the complete dynamical models with spontaneous R-parity breaking proposed previously. We comment on the lowest-lying CP-even Higgs boson mass and discuss its minimal N=1 supergravity limit, determine the ranges of $\tan\beta$ and bottom quark Yu…
SU(2|1) symmetry, algebraic superconnections and a generalized theory of electroweak interactions
1991
We discuss an extension of the standard model of electroweak interactions which incorporates the usual gauge fields and the Higgs fields in one generalized Yang-Mills field (or superconnection). It is shown that both this Yang-Mills field and the corresponding field strength (supercurvature) take their values in the real, graded Lie algebra SU(2|1). The lagrangian as obtained from this superconnection yields the standard model with interesting predictions for masses and couplings. The primordial, larger symmetry is realized as a hidden symmetry. The odd part survives in relations between couplings and masses, while the even part is broken to U(1)em, as usual, though in “reverse order” as co…
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…
Electroweak and finite width corrections to top quark decays into transverse and longitudinal $ W $-bosons
2002
We calculate the electroweak and finite width corrections to the decay of an unpolarized top quark into a bottom quark and a $ W $-gauge boson where the helicities of the $ W $ are specified as longitudinal, transverse-plus and transverse-minus. Together with the $ O(\alpha_s) $ corrections these corrections may become relevant for the determination of the mass of the top quark through angular decay measurements.
Global fits in the coloured scalar model
2020
Abstract In this work we study the phenomenological constraints on the parameter space of scalars carrying colour quantum numbers. In particular we constrain the Manohar-Wise model based on the addition of a SU(2) doublet and SU(3) octet to the minimal Higgs model. The fits are performed using the open-source package HEPfit . We include both theoretical constraints, such as unitarity and perturbativity, and experimental constraints, like the ones coming from flavour and electroweak observables. For the first time we combine all these results and we are able to constrain the parameters of the potential, the Yukawa couplings and the masses of the scalars.
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…
Measurement of charge asymmetry in hadronic Z decays
1991
A significant charge asymmetry is observed in the hadronic Z decays with the ALEPH detector at LEP. The asymmetry expressed in terms of the difference in momentum weighted charges in the two event hemispheres is measured to be − = −0.0084±0.0015 (stat.) ±0.0004 (exp. sys.). In the framework of the standard model this can be interpreted as a measurement of the effective electroweak mixing angle, sin2Ow (Mz2=0.2300±0.0034 (stat.) ±0.0010 (exp. sys.) ±0.0038 (theor. sys.) or of the ratio of the vector to axual- vector coupling costants of the electron, gvegAe=+0.073±0.024.
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.
Lepton asymmetries and the growth of cosmological seed magnetic fields
2007
Primordial cosmological hypermagnetic fields polarize the early Universe plasma prior to the electroweak phase transition (EWPT). As a result of the long range parity violating gauge interaction present in the Standard Model their magnitude gets amplified, opening a new, perturbative way, of accounting for the observed intergalactic magnetic fields.
Bounds on Neutrino Transition Magnetic Moments in Random Magnetic Fields
1995
We consider the conversions of active to sterile Majorana neutrinos $\nu_{a}$ and $\nu_{s}$, due to neutrino transition magnetic moments in the presence of random magnetic fields (r.m.f.) generated at the electroweak phase transition. From a simple Schr\"{o}dinger-type evolution equation, we derive a stringent constraint on the corresponding transition magnetic moments and display it as a function of the domain size and field geometry. For typical parameter choices one gets limits much stronger than usually derived from stellar energy loss considerations. These bounds are consistent with the hypothesis of seeding of galactic magnetic fields by primordial fields surviving past the re-combina…