Search results for "Arms"
showing 10 items of 182 documents
Production mechanisms and signatures of isosinglet neutral heavy leptons in Z0 decays
1990
Abstract Neutral Heavy Leptons (NHLs) arise in many extensions of the standard electroweak theory such as superstring inspired models. The possibility of gauge singlets NHLs is especially attractive because it gives an explanation for the observed smallness of the neutrino mass. Existing limits on the possible existence of such particles are still fairly poor. We have investigated isosinglet NHL production and decays within different models. The dominant production cross section is single production (i.e. Z 0 → N + ν or Z 0 → N + ν ) as a result of mixing with the standard doublet neutrinos. Subsequent NHL decays lead to striking signatures. Taking into account the expected luminosities and…
Neutrino electron scattering and left-right symmetry: future tests
1998
Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We propose the use of radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO and HELLAZ as a probe of the weak neutral current structure. As an illustration, we display the sensitivity of these detectors in testing the possible existence of right-handed weak neutral currents.
Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances
2012
We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum numbers. We examine the scattering amplitudes and their poles, which can be associated to known $J^P=1/2^-,3/2^-$ baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass of the resonances generated with only the basis of vector-baryon states.
X(3872)→J/ψγdecay in theDD¯*molecular picture
2012
From a picture of the X(3872) where the resonance is a bound state of $\bar{D}D^*-c.c.$, we evaluate the decay width into the $J/\psi \gamma$ channel, which is sensitive to the internal structure of this state. For this purpose we evaluate the loops through which the X(3872) decays into its components, and the $J/\psi$ and the photon are radiated from these components. We use the local hidden gauge approach extrapolated to SU(4) with a particular SU(4) breaking. The radiative decay involves anomalous couplings and we obtain acceptable values which are compared to experiments and results of other calculations. Simultaneusly, we evaluate the decay rate for the X(3872) into $J/\psi \omega$ and…
BRST-driven cancellations and gauge invariant Green's functions
2004
We study a fundamental, all order cancellation operating between graphs of distinct kinematic nature, which allows for the construction of gauge-independent effective self-energies, vertices, and boxes at arbitrary order.
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…
The fixed angle scattering problem with a first order perturbation
2021
We study the inverse scattering problem of determining a magnetic field and electric potential from scattering measurements corresponding to finitely many plane waves. The main result shows that the coefficients are uniquely determined by $2n$ measurements up to a natural gauge. We also show that one can recover the full first order term for a related equation having no gauge invariance, and that it is possible to reduce the number of measurements if the coefficients have certain symmetries. This work extends the fixed angle scattering results of Rakesh and M. Salo to Hamiltonians with first order perturbations, and it is based on wave equation methods and Carleman estimates.
Charge and magnetic moment of the neutrino in the background field method and in the linear R-xi(L) gauge
1999
We present a computation of the charge and the magnetic moment of the neutrino in the recently developed electro-weak Background Field Method and in the linear $R_{\xi}^L$ gauge. First, we deduce a formal Ward-Takahashi identity which implies the immediate cancellation of the neutrino electric charge. This Ward-Takahashi identity is as simple as that for QED. The computation of the (proper and improper) one loop vertex diagrams contributing to the neutrino electric charge is also presented in an arbitrary gauge, checking in this way the Ward-Takahashi identity previously obtained. Finally, the calculation of the magnetic moment of the neutrino, in the minimal extension of the Standard Model…
Observability of the Neutrino Charge Radius
2002
It is shown that the probe-independent charge radius of the neutrino is a physical observable; as such, it may be extracted from experiment, at least in principle. This is accomplished by expressing a set of experimental ${\ensuremath{\nu}}_{\ensuremath{\mu}}\mathrm{\text{\ensuremath{-}}}e$ cross sections in terms of the finite charge radius and two additional gauge- and renormalization-group-invariant quantities, corresponding to the electroweak effective charge and mixing angle.
Signatures of bosonic squark decays in non-minimally flavour-violating supersymmetry
2010
We investigate couplings of squarks to gauge and Higgs-bosons within the framework of non-minimal flavour violation in the Minimal Supersymmetric Standard Model. Introducing non-diagonal elements in the mass matrices of squarks, we first study their impact on the self-energies and physical mass eigenvalues of squarks. We then present an extensive analysis of bosonic squark decays for variations of the flavour-violating parameters around the two benchmark scenarios SPS1a' and SPS1b. Signatures, that would be characteristic for a non-minimal flavour structure in the squark sector, can be found in wide regions of the parameter space.