Particle Mass Spectra Research Articles

Particle Spectra and Gauge Unification in SU(6) xSU(2)R Model

We study the path from the string scale physics to the low-energy physics in the $SU(6) \times SU(2)_R$ string-inspired model with the flavor symmetry ${\bf Z}_M \times {\bf Z}_N \times \tilde{D}_4$. The flavor symmetry controls the mass spectra of heavy particles as well as those of quarks and leptons in the intermediate energy region ranging from the string scale ($\sim 10^{18} {\rm GeV}$) to the electroweak scale. In this paper we examine the mass spectra of heavy particles in detail in our model. The renormalization group evolution of the gauge couplings is studied up to two-loop order. A consistent solution of the gauge unification around the string scale is found by adjusting the spectra of the anti-generation matter fields.

Spectrum of TeV particles in warped supersymmetric grand unification

In warped supersymmetric grand unification, XY gauge particles appear near the TeV scale along with Kaluza-Klein towers of the standard model gauge fields. In spite of this exotic low-energy physics, the successful gauge coupling unification prediction of the minimal supersymmetric standard model (MSSM) is preserved and proton decay is naturally suppressed. In this paper we study in detail the low-lying mass spectrum of superparticles and grand unified particles in this theory, taking supersymmetry breaking to be localized to the TeV brane. The masses of the MSSM particles, Kaluza-Klein modes, and XY states are all determined by two parameters, one that fixes the strength of the supersymmetry breaking and the other that sets the scale of the infrared brane. A particularly interesting result is that for relatively strong supersymmetry breaking, the XY gauginos and the lowest Kaluza-Klein excitations of the MSSM gauginos may both lie within reach of the CERN Large Hadron Collider, providing the possibility that the underlying unified gauge symmetry and the enhanced $N=2$ supersymmetry of the theory will both be revealed.

Visualizing the mass and width spectrum of unstable particles

Unstable particles are characterized by their mass and mass uncertainty, in addition to other kinematic and internal parameters. The mass uncertainty is called the width of the unstable particle and can be theoretically related to the particle lifetime by the Weisskopf–Wigner relation. Several graphical representations of the mass and width spectrum of unstable subatomic particles are presented. Such plots are useful tools for introducing students to the particle zoo and provide students an alternate way to organize conceptually what can seem like an overwhelming amount of data. In particular, such graphs highlight phenomenological features of unstable particles characteristic of different energy and time scales.

On a connection between the VAK, knot theory and El Naschie’s theory of the mass spectrum of the high energy elementary particles

In the present work we give an introduction to the ε (∞) Cantorian space–time theory. In this theory every particle can be interpreted as a scaling of another particle. Some particles are a scaling of the proton and are expressed in terms of φ and α 0 . Following the VAK suggestion of El Naschie, the limit sets of Kleinian groups are Cantor sets with Hausdorff dimension φ or a derivative of φ such as 1/ φ, 1/ φ 2, 1/ φ 3, etc. Consequently and using ε (∞) theory, the mass spectrum of elementary particles may be found from the limit set of the Möbius–Klein geometry of quantum space–time as a function of the golden mean φ=( 5 −1)/2=0.618033989 as discussed recently by Datta (see Chaos, Solitons & Fractals 17 (2003) 621–630).

Is the energy density of the ground state of the sine-Gordon model unbounded from below for 2> 8 ?

We discuss Coleman's theorem concerning the energy density of the ground state of the sine-Gordon model proved in Coleman S (1975 Phys. Rev. D 11 2088). According to this theorem the energy density of the ground state of the sine-Gordon model should be unbounded from below for coupling constants β2 > 8π. The consequence of this theorem would be the non-existence of the quantum ground state of the sine-Gordon model for β2 > 8π. We show that the energy density of the ground state in the sine-Gordon model is bounded from below even for β2 > 8π. This result is discussed in relation to Coleman's theorem (Coleman S 1973 Commun. Math. Phys. 31 259), particle mass spectra and soliton–soliton scattering in the sine-Gordon model.

Cluster Analysis of Data from the Particle Analysis by Laser Mass Spectrometry (PALMS) Instrument

We describe the use of a hierarchical clustering algorithm on mass spectra of single particles. In this method, the first cluster is found by searching a data set for the two most similar mass spectra. Then the next most similar spectra or clusters are combined sequentially until a stopping condition is met. Chemically reasonable clusters were obtained for several sets of both laboratory and ambient aerosols. Advantages of this technique include assured convergence without multiple iterations, the ability to handle clusters with widely varying numbers of elements, and good performance even when a continuum of points connects different clusters. A disadvantage of this hierarchical clustering is that it operates on a fixed data set and cannot assign spectra to clusters as the spectra are obtained.

The Cantorian interpretation of high energy physics and the mass spectrum of elementary particles

The paper is a rather informal introduction to the concepts and results of the E-infinity Cantorian theory of quantum physics.

Hydroxymethanesulfonate as a tracer for fog processing of individual aerosol particles

Hydroxymethanesulfonate (HMS), an important component in fog and cloud systems, is identified in the negative ion mass spectra of individual particles sampled with an aerosol time-of-flight mass spectrometer (ATOFMS). The peak assignment at mass/charge ( m/ z)–111 is confirmed by analyzing HMS particles produced in the laboratory. Individual particle mass spectra from a field campaign in Bakersfield, California reveal the presence of HMS in the ambient aerosol during isolated time periods near the dissipation phase of fog suggesting fog processing of the aerosol. The lifetime of HMS in the aerosol is limited to less than 12 h. Using the presence of HMS as a tracer for aqueous-phase fog processing, the size distribution indicates that particles with aerodynamic diameters greater than 0.7 μm are most affected by the fog and associated high relative humidity. HMS is predominantly associated with particles containing carbon, ammonium, sulfate, and nitrate. Examination of elemental carbon particles containing HMS shows the presence of organic carbon which most likely enhances the hygroscopicity of these particles. This study demonstrates the ability for real-time measurements of fog processing at the single particle level using a chemical tracer for aqueous-phase reactions and highlights the possibilities for using high temporal resolution measurements to gain unique insights into atmospheric processes.

Nitrate and oxidized organic ions in single particle mass spectra during the 1999 Atlanta Supersite Project

We measured the chemical components of 0.35–2.5 μm diameter aerosols with a Particle Analysis by Laser Mass Spectrometry (PALMS) instrument during the Atlanta Supersite Project in August 1999. This paper presents the results for nitrate and oxidized organics. More than 20% of the negative ion spectra of single particles contained nitrate ion peaks. Nitrate peaks showed a clear maximum during the morning at the time of high ambient relative humidity. Nitrate peaks also had a small local maximum during the afternoon when the gas‐phase HNO3 concentrations were high. This afternoon maximum was more significant for the particles containing soot/hydrocarbons or aluminosilicate components than for the typical organic/sulfate particles. About 45% of negative spectra contained ions indicative of the oxidized organics. Oxidized organic peaks showed a diurnal variation similar to the nitrate: a morning time maximum during the relative humidity maximum and a small maximum in the afternoon. However, in contrast to the nitrate peaks, the afternoon local maximum of oxidized organic peaks was apparent on the organic/sulfate particles. Both nitrate and oxidized organic peaks had larger ion fractions in particles with higher scattered light intensities.

Reproducibility of Single Particle Chemical Composition during a Heavy Duty Diesel Truck Dynamometer Study

The chemical reproducibility of single particle mass spectrometry (SPMS) instruments is complicated by numerous factors, including uncertainties in the laser desorption/ionization process leading to shot-to-shot variability in single particle mass spectra, excessive fragmentation of carbonaceous species, as well as a relatively low duty cycle (1-10 Hz). With source apportionment being a major application for these instruments, proper source profiles must be determined from major aerosol sources. This brief communication illustrates, for the first time, the chemical reproducibility of an aerosol time-of-flight mass spectrometer (ATOFMS) sampling highly transient heavy duty diesel (HDD) truck exhaust emissions from a transportable heavy duty vehicle emissions testing laboratory, which includes a dilution tunnel as well as a residence chamber.In addition to examining the reproducibility of ATOFMS using a complex mixture of real aerosol particles, the chemical reproducibility of a dynamometer system at the ...

Online analysis of atmospheric particles with a transportable laser mass spectrometer during LACE 98

A novel mobile mass spectrometric acquisition and evaluation system for on‐line analysis of single airborne particles and characterization of particle populations (aerosols), laser mass analyzer for particles in the airborne state (LAMPAS 2), was employed during the Lindenberg Aerosol Characterization Experiment 1998 in July and August 1998 (LACE 98). The major aim of this experiment was to perform a size‐resolved determination of the chemical composition of atmospheric particles within populations in order to evaluate the climate forcing created by anthropogenic aerosol particles. During the field campaign, the LAMPAS 2 instrument continuously analyzed size and composition of individual particles from five size ranges with a time course resolution of 1 hour, recording several ten thousand single‐particle spectra. By using a semiautomated data processing unit, the amount of data could be significantly reduced from several hundreds of particle mass spectra to only a few particle classes in every size range. Statistical evaluation of the mass spectral data measured during LACE 98 resulted in the determination of 10 basic classes of particles, yielding detailed information on the aerosol composition. Chemical interpretation of these particle classes and correlation to meteorological data and physicochemical particle properties (optical parameters) were performed.

Singular self-preserving regimes of coagulation processes.

The late stages of the time evolution of disperse systems when either coagulation alone governs the temporal changes of particle mass spectra or simultaneous condensation complicates the evolution process are studied under the assumption that the condensation efficiencies and coagulation kernels are homogeneous functions of the particle masses, with gamma and lambda being their homogeneity exponents, respectively. In considering the asymptotic behavior of the particle mass distributions the renormalization-group approach is applied to three types of coagulating systems: free coagulating systems in which coagulation alone is responsible for disperse particle growth; source-enhanced coagulating systems, where an external spacially uniform source permanently adds fresh small particles, with the particle production being a power function of time; and coagulating-condensing systems in which a condensation process accompanies the coagulation growth of disperse particles. The particle mass distributions of the form N(A)(g,t)=A(t)psi(gB(t)) are shown to describe the asymptotic regimes of particle growth in all the three types of coagulating systems (g is the particle mass). The functions A(t) and B(t) are normally power functions of time whose power exponents are found for all possible regimes of coagulation and condensation as the functions of lambda and gamma. The equations for the universality function psi(x) are formulated. It is shown that in many cases psi(x) proportional, variant x(-sigma) (sigma > 1) at small x, i.e., the particle mass distributions are singular. The power exponent sigma is expressed in terms of lambda and gamma. Two exactly soluble models illustrate the general theoretical consideration.

Detection of negative ions from individual ultrafine particles.

Aerosol mass spectrometers can be used to classify individual airborne particles on the basis of chemical composition. While positive ion mass spectra are normally used to characterize ultrafine particles (defined here as particles smaller than 200 nm in diameter), negative ion mass spectra can provide complementary information. To effectively utilize the negative ion mass spectra of ultrafine particles, it is important to understand biases in the formation and detection of negative ions. It is found that the intensity of negative ions is generally less than that of positive ions, due to the creation of electrons in the ablation process that must react to form negative ions. The ablation efficiency, defined as the probability that an ablated particle produces a detectable ion signal, exhibits both size and composition dependencies. The ablation efficiency for detection of negative ions follows the same trends as the ablation efficiency for the detection of positive ions: sodium chloride and ammonium nitrate have higher ablation efficiencies than oleic acid, and the ablation efficiency decreases with the particle diameter. The ablation efficiency of negative ions is less than or equal to the ablation efficiency of positive ions, and the relative difference increases as the particle diameter decreases. Pure ammonium sulfate particles exhibit an ablation efficiency too low to be measured in the present experiments. However, trace amounts of sulfate in mixed-composition particles can be readily detected in the negative ion mass spectra.

Toward an Infinite-Component Field Theory with a Double Symmetry: Interaction of Fields

We complete the first stage of constructing a theory of fields not investigated before; these fields transform according to Lorentz group representations decomposable into an infinite direct sum of finite-dimensional irreducible representations. We consider only those theories that initially have a double symmetry: relativistic invariance and the invariance under the transformations of a secondary symmetry generated by the polar or the axial four-vector representation of the orthochronous Lorentz group. The high symmetry of the theory results in an infinite degeneracy of the particle mass spectrum with respect to spin. To eliminate this degeneracy, we postulate a spontaneous secondary-symmetry breaking and then solve the problems on the existence and the structure of nontrivial interaction Lagrangians.

Gauge Coupling Unification with Anomalous U(1)A Gauge Symmetry

Recently we proposed a natural scenario of grand unified theories with anomalous U(1)_A gauge symmetry, in which doublet-triplet splitting is realized in SO(10) unification using Dimopoulos-Wilczek mechanism and realistic quark and lepton mass matrices can be obtained in a simple way. The scenario has an additional remarkable feature that the symmetry breaking scale and the mass spectrum of super heavy particles are determined essentially by anomalous U(1)_A charges. Therefore once all the anomalous U(1)_A charges are fixed, the gauge coupling flows can be calculated. We examine several models in which the gauge coupling unification is realized. Examining the conditions for the coupling unification, we show that when all the fields except those of the minimal SUSY standard model become super-heavy, the unification scale generically becomes just below the usual GUT scale \Lambda_G\sim 2\times 10^{16} GeV and the cutoff scale becomes around \Lambda_G. Since the lower GUT scale leads to shorter life time of nucleon, the proton decay via dimension six operator p\to e^+\pi^0 can be seen in future experiment. On the other hand, the lower cutoff scale than the Planck scale may imply the existence of extra dimension in which only gravity modes can propagate.

Chemical classes of atmospheric aerosol particles at a rural site in Central Europe during winter

Ambient atmospheric particles were studied at an ecosystem research site in the Fichtelgebirge mountains in Central Europe by single-particle analysis and bulk impactor measurements. Fuzzy clustering analysis of mass spectra of individual aerosol particles allowed chemical classification of the atmospheric aerosol. During the campaign, inorganic salts, mineral particles, and carbonaceous particles, with varying degrees of secondary components, were identified. These chemical classes exhibited preferential size ranges leading to a characteristic pattern of relative abundances with respect to particle size. A more detailed analysis revealed that 65–80% of all particles were assigned almost exclusively to one chemical class. These particle populations are assumed to be externally mixed with respect to the identified chemical classes. The temporal variations of the ratio of nitrate to ammonium (ranging between 0.37 and 0.81) determined by both impactor measurements and single-particle analyses were in good agreement. Through Monte-Carlo-type simulations, confidence intervals of the mean NO 3 −/NH 4 + ratio were calculated for sub-samples of the total particle population.

Single-particle mass spectrometry of polystyrene microspheres and diamond nanocrystals.

High-resolution mass spectra of single submicrometer-sized particles are obtained using an electrospray ionization source in combination with an audio frequency quadrupole ion-trap mass spectrometer. Distinct from conventional methods, light scattering from a continuous Ar-ion laser is detected for particles ejected out of the ion trap. Typically, 10 particles are being trapped and interrogated in each measurement. With the audio frequency ion trap operated in a mass-selective instability mode, analysis of the particles reveals that they all differ in mass-to-charge ratio (m/z), and the individual peak in the observed mass spectrum is essentially derived from one single particle. A histogram of the spectra acquired in 10(2) repetitions of the experiment is equivalent to the single spectrum that would be observed when an ion ensemble of 10(3) particles is analyzed simultaneously using the single-particle mass spectrometer (SPMS). To calibrate such single-particle mass spectra, secular frequencies of the oscillatory motions of the individual particle within the trap are measured, and the trap parameter qz at the point of ejection is determined. A mass resolution exceeding 10(4) can readily be achieved in the absence of ion ensemble effect. We demonstrate in this work that the SPMS not only allows investigations of monodisperse polystyrene microspheres, but also is capable of detecting diamond nanoparticles with a nominal diameter of 100 nm, as well.

Neutrino Masses, Anomalous U(1) Gauge Symmetry and Doublet-Triplet Splitting

We propose an attractive scenario of grand unified theories in which doublet-triplet splitting is naturally realized in SO(10) unification using the Dimopoulos-Wilczek mechanism. The anomalous U(1)A gauge symmetry plays an essential role in the doublet-triplet splitting mechanism. It is interesting that the anomalous U(1)A charges determine the unification scale and mass spectrum of additional particles, as well as the order of the Yukawa couplings of quarks and leptons. For the neutrino sector, bi-maximal mixing angles are naturally obtained, and proton decay via dimension 5 operators is suppressed. It is suggestive that the anomalous U(1)A gauge symmetry motivated by superstring theory effectively solves the two biggest problems in grand unified theories, the fermion mass hierarchy problem and doublet-triplet splitting problem.

Formation of aerosol particles from reactions of secondary and tertiary alkylamines: characterization by aerosol time-of-flight mass spectrometry.

In ambient field studies conducted with aerosol time-of-flight mass spectrometry (ATOFMS), individual particle mass spectra commonly contain ion peaks at mass/charge (m/z) 86, 101, 102, and 118. Particles with mass spectra containing these peaks show a strong correlation with high relative humidity and low temperatures. In an effort to identify these peaks, a series of smog chamber studies were conducted probing the chemistry of secondary and tertiary alkylamines. Specifically, in separate studies, trimethylamine, di- and triethylamine, and di- and tripropylamine were reacted in a 1 m3 Teflon outdoor smog chamber with naturally occurring levels of gas phase oxidants in ambient air. The aerodynamic sizes and individual mass spectra of the resulting aerosol particles were acquired continuously using aerosol time-of-flight mass spectrometry (ATOFMS). Both oxidation and acid-base reactions between amines and acids commonly present in the atmosphere (i.e., nitric and sulfuric acid) appear to play roles in the formation and chemistry of organic nitrogen-containing particle phase species. Ion peaks in the individual particle mass spectra indicate the presence of alkyl ammonium salts, as well as other tentatively identified organic N-containing compounds formed by oxidation processes. Also, for the first time, tertiary alkylamine-N-oxides have been identified as alkylamine oxidation products in the aerosol particle phase. Smog chamber reactions involving triethylamine produce ATOFMS mass spectra with similar ion peak combinations as those observed in the spectra of particles commonly detected in ambient and vehicular source characterization studies. The results of this study suggest that amine chemistry involving gas-to-particle conversion and photooxidation processes may play a significant role in particle formation in regions with high amine concentrations.

Kinetics of nucleation controlled formation and condensational growth of disperse particles

The kinetics of nucleation controlled formation and condensational growth of disperse particles is considered under the assumptions that: (i) only a small amount of condensable substance nucleates and forms the particles that grow by condensing the rest of the substance. (ii) The condensation efficiency is a power function of the particle mass. A nontrivial perturbation theory with respect to the smallness parameter mu= (the mass of nucleated matter)/(the total mass of condensable matter) is developed allowing one to describe the source-enhanced and free (no source) condensation processes in terms of universal functions: the particle-mass spectrum and the concentration of condensable matter. The theory relies upon a scaling transformation that removes at all the smallness parameter from the evolution equations (if the nucleation rate is a power function of the concentration of condensable matter) or leaves it in the expression for the nucleation rate where this parameter defines only a concentration scale of the nucleation process (for the nucleation rates of general form). The theory is illustrated by the exact analytical solutions of the nucleation-condensation kinetic equations for three practically important cases: (i) gas-to-particle conversion in the free-molecular regime, (ii) formation and diffusion controlled condensational growth of islands on surfaces, and (iii) formation and diffusion controlled growth of disperse particles in the continuum regime. The analytical expressions for the mass spectra of growing particles are found in the case of free condensing particles. The final mass spectra in free condensing systems display rather unusual behavior: they are either singular at small particle masses or not, depending on the value of the power exponent in the mass dependence of the condensation rate.