Charged Resonance Research Articles

Search for a Resonance Decaying intoWZBoson Pairs inpp¯Collisions

We present the first search for an electrically charged resonance W' decaying to a WZ boson pair using 4.1 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp collider. The WZ pairs are reconstructed through their decays into three charged leptons (l=e, mu). A total of 9 data events is observed in good agreement with the background prediction. We set 95% C.L. limits on the W'WZ coupling and on the W' production cross section multiplied by the branching fractions. We also exclude W' masses between 188 and 520 GeV within a simple extension of the standard model and set the most restrictive limits to date on low-scale technicolor models.

Mass-matching in Higgsless

Modern extra-dimensional Higgsless scenarios rely on a mass-matching between fermionic and bosonic KK resonances to evade constraints from precision electroweak measurements. After analyzing all of the Tevatron and LEP bounds on these so-called Cured Higgsless scenarios, we study their LHC signatures and explore how to identify the mass-matching mechanism, the key to their viability. We find singly and pair produced fermionic resonances show up as clean signals with 2 or 4 leptons and 2 hard jets, while neutral and charged bosonic resonances are visible in the dilepton and leptonic W ± Z 0 channels, respectively. A measurement of the resonance masses from these channels shows the matching necessary to achieve S ≃ 0. Moreover, a large single production of KKfermion resonances is a clear indication of compositeness of SM quarks. Discovery reach is below 10 fb−1 of luminosity for resonances in the 700 GeV range.

Effects of magnetic configuration on hot electrons in highly charged ECR plasma

To investigate the hot electrons in highly charged electron cyclotron resonance (ECR) plasma, Bremsstrahlung radiations were measured on two ECR ion sources at the Institute of Modern Physics. Used as a comparative index of the mean energy of the hot electrons, a spectral temperature, Tspe, is derived through a linear fitting of the spectra in a semi-logarithmic representation. The influences of the external source parameters, especially the magnetic configuration, on the hot electrons are studied systematically. This study has experimentally demonstrated the importance of high microwave frequency and high magnetic field in the electron resonance heating to produce a high density of hot electrons, which is consistent with the empirical ECR scaling laws. The experimental results have again shown that a good compromise is needed between the ion extraction and the plasma confinement for an efficient production of highly charged ion beams. In addition, this investigation has shown that the correlation between the mean energy of the hot electrons and the magnetic field gradient at the ECR is well in agreement with the theoretical models.

Electron interaction with S 6-C 60(CF 3) 12: Energy pool of fullerene cage

Electron impact study of isomer S 6-C 60(CF 3) 12 resulted in the ionization efficiency curves (IEC) of singly and doubly charged positive ions and electron capture resonances for negative ones. The appearance energy (AE) values of the fragment C 60(CF 3) n ions appear to correlate linearly with n down to n = 0 (C 60 ion) and its value for each additional act of CF 3 detachment rises by 2–3 eV. Observations of metastable ions reveal several cases of quasi-simultaneous detachment of two CF 3-groups. Energy shift between ionization energy of S 6-C 60(CF 3) 12 and AE of the first fragment C 60(CF 3) 11 ion was observed as 8.8 eV for singly and 8.3 eV for doubly charged ions. To rationalize this energy shift a DFT calculation of the orbital energies for the C 60(CF 3) 12 + cation have been carried out and energy gap between HOMO and LUMO orbitals was estimated. High probability of occupation of the localized σ* orbital and CF 3-elimination require four electron excitation and can be effected via a multielectron transition from the multitude of the densely distributed occupied π orbitals. The analogies with the fragmentation of C 60 with C 2-elimination are mentioned.

Charged exciton resonances in two and three dimensions

Resonances of three-body Coulomb systems are investigated in two and three dimensions. The complex scaling method combined with the stochastic variational approach has been used to calculate the position (energy and width) of the resonance states. The dependence of the resonance states on the mass ratio of the constituents and the dimensionality of the space is studied. It is found that the width of the resonance states behaves very differently in 2D and 3D for molecule-like cation systems. The calculated lifetimes of the resonances are in the nano- and picosecond region, and these states might be experimentally observable in excitonic trions in semiconductor quantum dots.

Self-consistent Monte Carlo simulation of particle motion and photon transport in the Argon positive column

A highly accurate self-consistent Monte Carlo method including charged and neutral particle motion and resonance photon transport is developed and applied to the simulation of the positive column of Argon discharge. The distribution of power loss across the tube is investigated. It is shown that negative slope of the current–voltage gradient curve can not be explained by only one factor. Diffusion of metastable atoms to the tube wall in the case of low current (0.2–3 mA) is responsible for the most part of negative slope. For the high currents the variation of radiation power loss makes a main contribution to the amplitude of the negative slope.

PROPOSAL FOR DIRECT SEARCH FOR STRONGLY BOUND STATES OF $p\bar p$, $n\bar p$ SYSTEMS WITH HIGH INTENSITY AND COLLECTIVE $\bar p$ BEAM

Here, we discuss the possibility of showing the existence of [Formula: see text] and [Formula: see text] bound states. Measurement of the single γ-ray from [Formula: see text] and [Formula: see text] systems at rest can directly confirm whether X(1860) and X(1835) are the resonances which are strongly coupled to [Formula: see text]. In addition to the neutral candidate, a charged resonance X- is also proposed to be searched for in [Formula: see text] channel. We find that the data from the Crystal Barrel experiment at LEAR/CERN can be used to confirm the X(1835) observed by BES collaboration. The possibility of measuring the γ spectrum below 100 MeV at the new experiment with cold high intensity [Formula: see text] beam at GSI is discussed. These new techniques can be used to probe the structure of the X(1860) and X(1835) in the future.

Collider Phenomenology of the Higgsless Models

We identify and study the signatures of the recently proposed Higgsless models at the CERN Large Hadron Collider (LHC). We concentrate on tests of the mechanism of partial unitarity restoration in the longitudinal vector boson scattering, which is crucial to the phenomenological success of any Higgsless model and does not depend on the model-building details. We investigate the discovery reach for charged massive vector boson resonances and show that all of the preferred parameter space will be probed with 100 fb(-1) of LHC data. Unitarity restoration requires that the masses and couplings of the resonances obey certain sum rules. We discuss the prospects for their experimental verification at the LHC.

Scintillator probe for lost alpha measurements in JET

Good confinement of alpha particles in a large magnetic fusion device is a precondition for building a magnetic fusion reactor. The direct measurement of alpha particle losses is of particular interest. Appropriate diagnostics are now being prepared for the Joint European Torus tokamak: a scintillator probe and a set of Faraday cups. Both systems are capable of measuring charged fusion products and ion cyclotron resonance heating tail ions. The design of the lost alpha particle scintillator probe is in the scope of this article. It will allow the detection of particles with a gyroradius between 20 and 140 mm (15% resolution) and a pitch angle between 30° and 86° (5% resolution). As scintillating material P56 will be used. The light emitted by the scintillator caused by charged particles that pass the collimator and hit the scintillator will be detected via a set of optical lenses and a coherent image fiber bundle with a charge coupled device camera and a photomultiplier array. In the following the present design of the scintillator probe with emphasis on the performance of the system, structural resistance against plasma disruptions, and the requirements on the heat protection against plasma and neutral beam induced thermal loads will be described.

Atom-to-ion transformation time in singly charged ECRISs

We report a series of measurements performed to characterize the atom-to-ion transformation time in singly charged electron cyclotron resonance ion sources (ECRISs). Three ECRISs were used with He, Ne, Ar and Kr noble gases. The transformation time as a function of the support gas flow, the ionization efficiency, and source volume is presented and compared to a calculation made with a simple dynamic model.

Charged vortices and copper nuclear quadrupole resonance in the cuprates

The charge density induced at $T=0$ by a vortex in a type-II superconductor is studied, starting from the Lagrangian for a nonlinear Schr\"odinger equation. Coupled Bernoulli and Poisson equations are solved assuming that the electrostatic screening length is much shorter than the superconducting coherence length. The sign and magnitude of the charge accumulated in the vortex core agree with recent nuclear quadrupole resonance data of Kumagai, Nozaki, and Matsuda [Phys. Rev. B 63, 144502 (2001)] on slightly overdoped ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}.$

CP violation and the absence of second class currents in charmless B decays

The absence of second class currents together with the assumption of factorization for non-leptonic B decays provide new constraints on CP observables in decay B to a0(980)(to eta pi) pi. The kinematics of this decay do not allow interference between the oppositely charged resonances in the Dalitz plot as in B0 to rho(770)pi. Nonetheless, under the assumption of factorization,the a0pi two-body time-dependent isospin analysis leads to a more robust extraction of the angle alpha than in the rhopi isospin-pentagon analysis. The absence of second class currents might lead to enhanced direct CP violation and/or allows for a test of some assumptions made in the alpha analysis in other decays like B to a0rho, B to b1(1235)pi, B to a0 a0, B to eta(eta')pipi and B to b1 a0. The effects from non-factorizable contributions on the determination of alpha are estimated by means of a numerical study.

New Method for Detecting Charged Scalars at Colliders

We propose a new method for detecting a charged (pseudo-)scalar at colliders, based upon the observation that its Yukawa coupling to charm and bottom quarks can be large due to a significant mixing of the top and charm quarks. After analyzing the typical flavor mixing allowed by low energy data in the topcolor and the generic two-Higgs doublet models, we study the physics potential of the Tevatron, LHC, and linear colliders for probing such an s-channel charged resonance via the single-top (as well as Wh^0) production. We show that studying its detection at colliders can also provide information on the dynamics of flavor-changing neutral current phenomena.

Left-right asymmetries in polarized lepton-lepton scattering

Several parity violating left-right asymmetries in M\o ller electron-electron and muon-muon scattering are considered in the context of the electroweak standard model at tree level in fixed target and collider experiences. We show that in colliders the asymmetry with only one of the beam polarized is large enough to compensate the smaller cross section at high energies. We also show that these asymmetries are very sensitive to a doubly charged vector bilepton resonance but they are insensitive to scalar ones.

Constraints on neutrino parameters and doubly-charged Higgs particles in e−e− → W−W−

Doubly charged Higgs s-channel resonances are analyzed in the e − e − → W − W − process. In our analysis a recent stringent constraint on an effective neutrino mass 〈 m v 〉 coming from neutrinoless double-β decay is implemented. It is shown that due to a very restrictive limit on 〈 m v 〉 the doubly charged Higgs resonance predicted by the Standard Model with additional Higgs triplets is below the detection limit. For the same reason also the Δ L −− resonance cannot be visible in the framework of the conventional Left-Right symmetric model. The situation is quite different for the Δ R −− pole and large signal is possible here. Contributions of the s, t and u channels to the cross section around the Δ R −− peak are also discussed.

High energy neutral particle analyzer

The paper describes a high energy neutral particle analyzer (HENPA) developed in the Ioffe Institute for the diagnostics of alpha particles in the megaelectronvolt energy range, as well as other charged fusion products and ion cyclotron resonance frequency-driven minority ions in a plasma. Megaelectronvolt ions can be neutralized in the plasma by charge exchange reactions with low energy atoms or impurity ions, and by recombination. The density of target particles for neutralization can be increased in the plasma by neutral beam or pellet injection. The operation of the HENPA is based on stripping megaelectronvolt atoms by means of a carbon foil, and subsequent E | B analysis of secondary ions. Eight (or 2 × 8, depending on the version) detectors that consist of (CsI + TI) scintillators 2–25 μm thick optically coupled to photomultiplier tubes are used to detect secondary ions. The detection efficiency of the detectors for megaelectronvolt ions is close to 100%; it drops to 10 −4 − 10 −8 for D-T neutrons, and to much lower values for D-D neutrons and gamma quanta in the energy range above 1 MeV. The HENPA is calibrated using megaelectronvolt H 0-He 0 beams from the cyclotron, starting from 0.4 MeV for He 0 and 0.1 MeV for H. The energy ratio of simultaneously detected particles is E max E min ≈ 4 . The energy widths of the channels are 6%–15%. The HENPA can operate in a stray magnetic field up to 0.07 T. Some examples of results obtained by the HENPA are presented.

Parity violation in charged particle resonances

Recent parity nonconservation (PNC) measurements in nuclei use the compound nucleus as a laboratory for the study of symmetry breaking, with the symmetry breaking matrix elements treated as random variables. This approach is made appealing by the observation of very large parity violation in neutron resonances. One key issue is the mass dependence of the effective nucleon-nucleus weak interaction. The neutron measurements do not appear feasible for light nuclei. We have calculated PNC observables for charged particle resonance reactions for over 100 states in five s-d shell nuclides using experimental values of the resonance parameters. Analyzing powers show strong dependence on energy and angle, and vary greatly from resonance to resonance. Proposed PNC experiments are discussed.

Resonant electron transfer at metal surfaces: Theoretical analysis of scaling properties and universal behavior.

The resonant electron transfer processes that occur when slowly moving atoms and (positive) ions interact with metal surfaces are theoretically analyzed with regard to scaling properties and universal behavior. Within the first-order adiabatic approximation, a simple model is employed that allows a systematic (formal and numerical) study of the dependence of transition matrix elements and transition rates upon the parameters characterizing the ion-metal system. Scaling parameters are introduced, through which scale transformations of the system parameters are defined. The ion-surface distance, in particular, is scaled by means of the ``classical threshold distance,'' below which, at given electronic energy, resonant electron transfer is classically allowed. When transformed to the scaled representation, transition matrix elements and rates are found to be expressible in terms of ``reduced,'' universal functions, which are independent of the parameters characterizing the strength of the electronic potentials in the ion-metal system. In the limit of large ionic principal quantum numbers, the behavior of transition matrix elements and rates is largely determined by three universal functions that depend on the scaled ion-surface distance only. Scaling laws connecting transition matrix elements and rates for different ionic principal quantum numbers are established. Resonance neutralization of highly charged ions and resonance ionization of Rydberg atoms are considered as specific cases. Quasiclassical aspects and possible applications of our results as well as extensions of our analysis are briefly discussed.

Parity violation in charged particle nuclear reactions.

The potential role of charged particle resonance reactions in the study of parity nonconservation (PNC) in the nucleus is examined in light of recent statistical interpretations of PNC measurements in neutron resonances. Several PNC observables have been calculated using experimental resonance parameters for five s-d shell nuclei. Longitudinal analyzing powers in (p\ensuremath{\rightarrow},${\mathrm{\ensuremath{\alpha}}}_{0}$) reactions show strong dependence on energy, angle, and resonance parameters. Measurements of analyzing powers at the ${10}^{\mathrm{\ensuremath{-}}4}$ level should provide new information on parity vaiolation in the nucleon-nucleus interaction.

Identification of structural markers for vitamin B12 and other corrinoid derivatives in solution using FTIR spectroscopy

The identification of structural markers for B12/protein interactions is crucial to a complete understanding of vitamin B12 transport and metabolic reaction mechanisms of B12 coenzymes. Fourier transform infrared spectroscopy can provide direct measurements of changes in the side chains and corrin ring resulting from B12/protein interactions. Using FTIR spectroscopy in various solvent systems, we have identified structural markers for corrinoids in the physiological state. We assign the major band (denoted B), which occurs at ca. 1630 cm-1 in D2O and ca. 1675 cm-1 in ethanol, to the amide I C=O stretching mode of the propionamide side chains of the corrin ring. The lower frequency of band B in D2O versus ethanol is due to the greater hydrogen-bonding properties of D2O that stabilize the charged amide resonance form. Since the propionamides are known to be important in protein binding, band B is a suitable marker for monitoring the interaction of these side chains with proteins. We assign bands at ca. 1575 and 1545 cm-1 (denoted C and D) as breathing modes of the corrin ring on the basis of the bands' solvent independence and their sensitivity to changes in axial ligation. As the sigma-donating strength of the axial ligands increases, the frequencies of bands C and D decrease, possibly indicating a lengthening of the corrin conjugated system. Band A, the known cyanide stretching frequency at ca. 2130 cm-1, probes the cobalt-carbon distance in cyanocorrinoids. As the frequency of band A increases, the cobalt-carbon bond strength should decrease.