<p>Broadband extremely low-frequency wave emissions below the ion plasma frequency have been observed by a number of spacecraft and rockets on auroral field lines. The importance of these broadband emissions for transverse ion heating and electron acceleration in the auroral regions is now reasonably well established. However, the exact mechanism(s) for mediating this energy transfer and the wave mode(s) involved are not well known. In this thesis we focus on the identification of broadband waves by different methods. </p><p>Two wave analysis methods, involving different approximations and assumptions, give consistent results concerning the wave mode identification. We find that much of the broadband emissions can be identified as a mixture of ion acoustic, electrostatic ion cyclotron and, ion Bernstein waves, which all can be described as different parts of the same dispersion surface in the linear theory of waves in homogeneous plasma. </p><p>A new result is that ion acoustic waves occur on auroral magnetic field lines. These are found in relatively small regions interpreted as acceleration regions without cold (tens of eV) electrons.</p><p>From interferometry we also determine the phase velocity and k vector for parallel and oblique ion acoustic waves. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength is around the proton gyro radius and always larger than the Debye length which is consistent with ion acoustic waves. </p><p>We have observed quasi-static parallel electric fields associated with the ion acoustic waves in regions with large-scale currents. Waves, in particular ion acoustic waves, can create an anomalous resistivity due to wave-particle interaction when electrons are retarded or trapped by the electric wave-field. To maintain the large-scale current, a parallel electric field is set up, which then can accelerate a second electron population to high velocities.</p>

Diese Arbeit analysiert Synchronisationsphaenomene, die in grossen Ensembles von interagierenden Oszillatoren auftauchen. Im speziellen werden die Effekte von Nicht-Isochronizitaet (die Abhaengigkeit der Frequenz von der Amplitude des Oszillators) auf den makroskopischen Uebergang zur Synchronisation im Detail studiert. Die neu gefundenen Phaenomene (Anomale Synchronisation) werden sowohl in Populationen von Oszillatoren als auch zwischen Oszillator-Ensembles untersucht. / This thesis analyses synchronization phenomena occurring in large ensembles of interacting oscillatory units. In particular, the effects of nonisochronicity (frequency dependence on the oscillator's amplitude) on the macroscopic transition to synchronization are studied in detail. The new phenomena found (Anomalous Synchronization) are investigated in populations of oscillators as well as between oscillator's ensembles.

Of the many waveforms the bowed string can assume, theso-called "Helmholtz motion" (Helmholtz 1862) gives the fullestsound in terms of power and overtone richness. The developmentof this steady-state oscillation pattern can take manydifferent paths, most of which would include noise caused bystick-slip irregularities of the bow-string contact. Of thefive papers included in the thesis, the first one shows, notsurprisingly, that tone onsets are considered superior when theattack noise has a very limited duration. It was found,however, that in this judgment thecharacterof the noise plays an important part, as thelistener’s tolerance of noise in terms of duration isalmost twice as great for "slipping noise" as for "creaks" or"raucousness" during the tone onsets. The three followingpapers contain analyses focusing on how irregular slip-sticktriggering may be avoided, as is quite often the case inpractical playing by professionals. The fifth paper describesthe triggering mechanism of a peculiar tone production referredto as "Anomalous Low Frequencies" (ALF). If properly skilled, aplayer can achieve pitches below the normal range of theinstrument. This phenomenon is related to triggering wavestaking "an extra turn" on the string before causing thestring’s release from the bow-hair grip. Since transverseand torsional propagation speeds are both involved, twodifferent sets of "sub-ranged" notes can be produced this way.In the four last papers wave patterns are analysed andexplained through the use of computer simulations. Key words: Key words: Bowed string, violin, musicalacoustics, musical transient, anomalous low frequencies,Helmholtz motion

Broadband extremely low-frequency wave emissions below the ion plasma frequency have been observed by a number of spacecraft and rockets on auroral field lines. The importance of these broadband emissions for transverse ion heating and electron acceleration in the auroral regions is now reasonably well established. However, the exact mechanism(s) for mediating this energy transfer and the wave mode(s) involved are not well known. In this thesis we focus on the identification of broadband waves by different methods. Two wave analysis methods, involving different approximations and assumptions, give consistent results concerning the wave mode identification. We find that much of the broadband emissions can be identified as a mixture of ion acoustic, electrostatic ion cyclotron and, ion Bernstein waves, which all can be described as different parts of the same dispersion surface in the linear theory of waves in homogeneous plasma. A new result is that ion acoustic waves occur on auroral magnetic field lines. These are found in relatively small regions interpreted as acceleration regions without cold (tens of eV) electrons. From interferometry we also determine the phase velocity and k vector for parallel and oblique ion acoustic waves. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength is around the proton gyro radius and always larger than the Debye length which is consistent with ion acoustic waves. We have observed quasi-static parallel electric fields associated with the ion acoustic waves in regions with large-scale currents. Waves, in particular ion acoustic waves, can create an anomalous resistivity due to wave-particle interaction when electrons are retarded or trapped by the electric wave-field. To maintain the large-scale current, a parallel electric field is set up, which then can accelerate a second electron population to high velocities.

We present in this thesis a detailed analysis of Higgs boson interactions at future colliders. In particular we examine, in a model independent way, the sensitivity of an Linear Collider in probing the interaction of Higgs boson with a pair of vector bosons with/without the use of polarized initial beams and/or the information on final state fermion polarization. We devise several observables which have definite transformation properties under discrete symmetry operations to constrain the different anomalous parts of the Higgs boson interactions having the same transformation properties. We also investigate effects of initial state radiation (ISR) and beamstrahlung on probes of anomalous Higgs boson couplings at higher center of mass energies. We begin the first chapter with an introduction of the Standard Model (SM) of particle physics. We mainly focus on the Higgs sector of the SM. In this chapter we review the electroweak (EW) symmetry breaking mechanism, viz. the Higgs mechanism, responsible for generating masses of all the particles in the SM. We briefly summarize the high precision tests of the SM. We discuss constraints on the mass of the SM Higgs boson derived from theoretical considerations such as stability of the electroweak vacuum, unitarity in scattering amplitudes, perturbativity of the Higgs self-coupling and no fine-tuning in the radiative corrections in the Higgs sector. Next we present the experimental bounds on the mass of the SM Higgs boson obtained from the direct searches of the Higgs boson at LEP and from the electroweak high precision measurements. We then discuss the importance of a general model independent approach to study properties of the Higgs boson and to verify the uniqueness of the SM. In the context of low energy effective theory, this analysis can be made by using the effective Lagrangian that contains higher dimensional operators. We conclude this chapter giving examples of dimension-6 operators which can contribute to the anomalous Higgs boson interactions that we analyze in this thesis. Second chapter contains the dominant Higgs boson production processes at an collider.In a model independent analysis we consider the effects of the most general ¯ (V = W Z) vertex, consistent with Lorentz invariance, for the process where f is any light fermion. This vertex also includes the possibility of CP violation and can be written as: where ki denote the momenta of the two W’s (Z’s), ǫναβis the antisymmetric tensor with ǫ0123 = 1. Previous studies showed that the squared matrix element of the process e+e−ZH does not include all the anomalous parts of a general ZZH vertex. Also it is obvious that one cannot analyse anomalous WWH couplings using this process. Hence we consider the full process e+e−ffH to probe all the anomalous parts of the VVH vertex. We devise a general and very elegant procedure to probe these couplings at an e+e−collider. We construct various combinations by taking dot and scalar triple product of momenta of initial and final state particles. These combinations have definite transformation properties under CP and naive time reversal (T˜)transformations. Hence the corresponding observables constructed using expectation value of sign of these combinations can probe a specific part of the anomalous VVH couplings whose coefficient in the effective Lagrangian has same transformation properties. We investigate the possible sensitivity to which the anomalous VVH couplings can be probed at a Linear Collider using these observables in the process e+e−ffH for unpolarized beams [1, 2]. We consider the case of a Linear Collider, operating at center of mass energy of 500 GeV, with an integrated luminosityof 500 fb−1 and assume a Higgs boson of mass 120 GeV. We impose various kinematical cuts on different final state particles to reduce backgrounds ¯and consider the events where H decays into bb with branching ratio 0.68. We can enhance or suppress the effect of the s-channel, Z-exchange diagram by imposing cut on the ¯invariant mass of the ff system. We use b-tagging efficiency to be 70%; a value expected to be possible in the collider environment. We first consider asymmetries involving either the polar or azimuthal angular distributions. Then we combine these informations to construct combined polar-azimuthal asymmetries in order to enhance the sensitivity. We obtain strong constraints on most of the anomalous parts of the ZZH vertex using cross section and these asymmetries. The process e+eν¯ −νH has two missing ν’s in the final state. Hence their momenta are not available to construct any observables. Therefore, direct probes for T˜-odd WWH couplings viz. ℑ(bW), ℜ(˜bW), cannot be constructed and only weak, indirect bounds are possible. Further, without using polarized beams the contamination from the ZZH vertex cannot be eliminated in the determination of WWH couplings. In the third chapter we analyze use of linearly polarized e+/e−beams and/or information on final state lepton polarization in probingthe interaction of the Higgs boson with a pair of vector bosons[3, 4]. We make several combinations of different particle momenta and spins. We then define observables as expectation values of signs of these combinations for longitudinally polarized beams and/or for production of final state τ’s with a definite helicity state. Use of polarization allows us to devise more observables as compared to the unpolarized case. We list the observables for which use of polarization affords a distinct gain in sensitivity. In our analysis we divide the total luminosity of 500 fb−1 equally among different polarization states of initial state e−/e+ and take the values 80% and 60% for e−/e+ respectively, foreseen at the ILC. We construct numerical combinations of various linearly polarized cross sections to enhance the contribution of ℜ(bZ) while getting rid of ΔaZand vice versa. It is necessary to construct such combinations of cross section as ℜ(bZ), ΔaZhave same CP and T˜transformation properties and hence there are no asymmetries that can be constructed to probe them individually. With these combinations it is possible to probe both these CP-and T˜-even couplings cleanly, using linearly polarized beams. We find that longitudinal beam polarization can improve the sensitivity to CP-odd ZZH couplings viz. ℜ(˜bZ), ℑ(˜bZ), by a factor of about 6 −7. We also construct observables for final state τ’s with definite helicity. We make a plausible assumption that it should be possible to isolate events with τ’s in definite helicity state with an efficiency of 40%. With this assumption we demonstrate that the use of final state τ polarization can improve the sensitivity to the CP-even and T˜-odd ZZH coupling (ℑ(bZ)) by a factor of about 3. Moreover use of final state τ-polarization measurement along with linearly polarized beams can improve the sensitivity for one of the CP-odd ZZH couplings (ℜ(˜bZ))bya factor of about 2.Use of longitudinally polarized beams can also help to reduce the contamination in the measurement of the WWH couplings coming from the ZZH vertex contribution. We also perform χ2-analysis using the observables for different polarizations. The cross section of the t–channel diagram increases with increasing center of mass energy. Therefore, off hand it may look like that going to higher energy can increase the sensitivity to WWH couplings. Hence in this chapter we further investigate possible gain in sensitivity going to higher center of mass energies[3, 4]. We use the same observables constructed with unpolarized beams and consider various center of mass energies ranging from 300 GeV to 3 TeV. We find that it is possible to increase the bZ)byabouta factor 2 1 TeVas compared to the case of 500 GeV. In this analysis we include the effects of initial state radiation (ISR) and beamstrahlung. Both the ISR and beamstrahlung =500 GeV, the ISR can affect cross sections for s–channel processes by 10−15%.However, we observe that the effects of ISR and beamstrahlung change both the SM and anomalous contributions more beneficial for the study of anomalous V V H couplings. In the last chapter we investigate the role of transversely polarized beams to constrain the anomalous V V H couplings[5]. Using transverse spin direction of e±it is possible to devise observables which are nonzero only for transversely polarized beams. Use of transverse beam polarization allows construction of completely independent probes of both the CP-and T˜-even anomalous ZZH couplings (ΔaZ, ℜ(bZ)), leading to independent determination of all the anomalous parts of the ZZH vertex. In addition the use of transverse beam polarization can also add to the sensitivity for one of the CP-odd ZZH couplings viz. ℜ(˜bZ). Measurement of final state τ-polarization with transversely polarized beams can in fact also offer improvement on the sensitivity for ℑ(bZ) which is even under CP-and odd under T˜-transformation. Use of transverse beam polarization cannot improve the bounds on the anomalous WWH couplings as the squared matrix element of the t– channel WW–fusion diagram does not have any transverse beam polarization dependent term. A summary of the results obtained in this thesis is follows. We have developed a general procedure to construct observables with specific CP and T˜transformation properties to probe various anomalous couplings of the Higgs boson to a pair of vector bosons (V = W/Z) at an e+/e−Linear Collider. We investigate probes of these couplings in the process e+e−ffH. This process gives access to those anomalous couplings which cannot be probed using angular distribution of the Z boson in the process e+eZH. We showed that it would be possible to obtain stringent bounds on some of the parts of the anomalous ZZH vertex even without using polarized beams and/or information on polarization of final state particles. Use of longitudinal beam polarization and/or final state τ polarization can significantly enhance the sensitivity in probing most of the anomalous parts of a general ZZH vertex. Use of longitudinal beam polarization also reduces the contamination from the ZZH couplings in the determination of the ˜T-even anomalous WWH couplings (ℜ(bW), ℑ(˜bW)). However, two missing neutrinos in the final state do not allow any direct probe of the T˜-odd WWH couplings (ℑ(bW), ℜ(˜bW)).We find that use of transverse polarization of the beams is essential to construct independent probes of the two anomalous ZZH couplings, which are even under CP and T˜transformations, viz.ΔaZand ℜ(bZ).We observed that there will be no significant gain 500 GeV), but with polarized beams is preferable from the point of view of studying anomalous V V H coupling. (For mathematical equations pl see the pdf file.)

In this thesis, the recently discovered Soft Gamma Ray Repeaters SGR J1833-0832, SWIFT J1822.3-1606 and SWIFT J1834.9-0846 are analysed using the archival Swift, RXTE, Chandra and XMM-Newton observations. The period fluctuations and timing noise properties of these sources are investigated. Spectral characteristics and long term frequency evolution of these sources are presented. Investigation for timing noise structure of these magnetars has shown a correlation between first frequency derivative of the spin frequency and torque noise strength.

In this thesis the nonlinear effects and heating are studied in inductively coupled plasma (ICP) in a regime of anomalous skin effect (nonlocal regime). In this regime the thermal motion of plasma electrons plays an important role, significantly influencing the processes associated with the penetration of electromagnetic field into plasma, such as the ponderomotive effect and heating of plasma by the field. We have developed a linear kinetic theory that describes the electron dynamics in ICP taking into account the electron thermal motion and collisions of electrons. This theory yields relatively simple expressions for the electron current in plasma, the ponderomotive force, and plasma heating. It describes correctly the thermal reduction of ponderomotive force in the nonlocal regime, which has been previously observed experimentally. It also describes the collisionless heating of plasma due to resonant interaction between the electromagnetic wave and plasma electrons. There is a good overall agreement of the results of our theory with the experimental data on ponderomotive force and plasma heating. Using our theory, we predicted a new effect of reduction of plasma heating compared to the purely collisional value, occurring at low frequencies. This effect has not been previously reported. The nonlinear effects of the electromagnetic field on the electron distribution function and on plasma heating, that are not accounted for in the linear kinetic theory, have been studied using a quasilinear kinetic theory, also developed in this thesis. Within the quasilinear approximation we have formulated the system of equations describing the slow response of plasma electrons to the fast oscillating electromagnetic field. As an example, these equations have been solved in the simplest case of cold plasma with collisions, and the nonlinear perturbation of the electron distribution function and its effect on the plasma heating have been found. It has been shown that the nonlinear modification of plasma heating occurs mainly due to the nonlinear effect of the magnetic component of the electromagnetic field. It has also been shown that at high frequencies the nonlinear effects vanish, and the heating is well described by the linear theory. To verify the predicted new effect of plasma heating reduction at low frequencies, as well as to investigate the nonlinear effect of the magnetic field on plasma heating for arbitrary amplitudes of electromagnetic field in plasma, we have developed a 1d3v Particle-In-Cell (PIC) numerical simulation code with collisions. The collisions were implemented into the PIC code using two different techniques: the direct Monte-Carlo technique for the electron-atom collisions, and the stochastic technique based on the Langevin equation for the electron-electron collisions. The series of numerical simulations by this code confirmed the results of our linear theory, particularly the effect of heating reduction at low frequencies that we predicted theoretically. Also, the nonlinear effects of electromagnetic field on plasma heating were studied using the PIC code in the cases of weak and strong electromagnetic fields. It has been shown that in the case of weak electromagnetic fields (corresponding to weak nonlinearity) the nonlinear effects lead to some enhancement of heating (compared to the linear theory) at low frequencies, followed by a small reduction of heating at higher frequencies. This observed nonlinear perturbation of heating in warm plasma with collisions is similar to that predicted by the quasilinear theory for the case of cold plasma with collisions. In the case of strong electromagnetic fields (corresponding to strong nonlinearity) the nonlinear effects lead to a further reduction of heating (compared to the linear theory) at low frequencies, as shown by the simulation, thus adding to the effect of reduction of heating predicted by the linear theory. The nonlinear effects are shown to vanish at high frequencies, as expected.

In this thesis the nonlinear effects and heating are studied in inductively coupled plasma (ICP) in a regime of anomalous skin effect (nonlocal regime). In this regime the thermal motion of plasma electrons plays an important role, significantly influencing the processes associated with the penetration of electromagnetic field into plasma, such as the ponderomotive effect and heating of plasma by the field. We have developed a linear kinetic theory that describes the electron dynamics in ICP taking into account the electron thermal motion and collisions of electrons. This theory yields relatively simple expressions for the electron current in plasma, the ponderomotive force, and plasma heating. It describes correctly the thermal reduction of ponderomotive force in the nonlocal regime, which has been previously observed experimentally. It also describes the collisionless heating of plasma due to resonant interaction between the electromagnetic wave and plasma electrons. There is a good overall agreement of the results of our theory with the experimental data on ponderomotive force and plasma heating. Using our theory, we predicted a new effect of reduction of plasma heating compared to the purely collisional value, occurring at low frequencies. This effect has not been previously reported. The nonlinear effects of the electromagnetic field on the electron distribution function and on plasma heating, that are not accounted for in the linear kinetic theory, have been studied using a quasilinear kinetic theory, also developed in this thesis. Within the quasilinear approximation we have formulated the system of equations describing the slow response of plasma electrons to the fast oscillating electromagnetic field. As an example, these equations have been solved in the simplest case of cold plasma with collisions, and the nonlinear perturbation of the electron distribution function and its effect on the plasma heating have been found. It has been shown that the nonlinear modification of plasma heating occurs mainly due to the nonlinear effect of the magnetic component of the electromagnetic field. It has also been shown that at high frequencies the nonlinear effects vanish, and the heating is well described by the linear theory. To verify the predicted new effect of plasma heating reduction at low frequencies, as well as to investigate the nonlinear effect of the magnetic field on plasma heating for arbitrary amplitudes of electromagnetic field in plasma, we have developed a 1d3v Particle-In-Cell (PIC) numerical simulation code with collisions. The collisions were implemented into the PIC code using two different techniques: the direct Monte-Carlo technique for the electron-atom collisions, and the stochastic technique based on the Langevin equation for the electron-electron collisions. The series of numerical simulations by this code confirmed the results of our linear theory, particularly the effect of heating reduction at low frequencies that we predicted theoretically. Also, the nonlinear effects of electromagnetic field on plasma heating were studied using the PIC code in the cases of weak and strong electromagnetic fields. It has been shown that in the case of weak electromagnetic fields (corresponding to weak nonlinearity) the nonlinear effects lead to some enhancement of heating (compared to the linear theory) at low frequencies, followed by a small reduction of heating at higher frequencies. This observed nonlinear perturbation of heating in warm plasma with collisions is similar to that predicted by the quasilinear theory for the case of cold plasma with collisions. In the case of strong electromagnetic fields (corresponding to strong nonlinearity) the nonlinear effects lead to a further reduction of heating (compared to the linear theory) at low frequencies, as shown by the simulation, thus adding to the effect of reduction of heating predicted by the linear theory. The nonlinear effects are shown to vanish at high frequencies, as expected.

We present a measurement of ppbar->Zγ + X -> e⁺e^-γ + X production using proton-antiproton collision data collected at the Collider Detector at Fermilab at a center of mass energy of 1.96 TeV. Zγ production provides a direct test of the triple neutral gauge couplings. A measurement of Zγ production cross section and search for anomalous ZZγ and Zγγ couplings are presented. The data presented are from 1.1 fb^-1 of ppbar integrated luminosity collected at the CDF Detector. Electrons from Z decays are selected with E_t > 20 GeV. Photons (E_t > 7 GeV) are required to be well-separated from the electrons. There are 390 eeγ candidate events found with 1.1 fb^-1 of data, compared to the SM prediction of 375.3 à ± 25.2 events. The Standard Model prediction for the cross section for ppbar-> e⁺e^-γ + X production at √s = 1.96 TeV is 4.5 à ± 0.4 pb. The measured cross section is 4.7 à ± 0.6 pb. The cross section and kinematic distributions of the eeγ events are in good agreement with theoretical predictions. Limits on the ZZγ and Zγγ couplings are extracted using the photon E_t distribution of eeγ events with M_eeγ > 100 GeV/c². These are the first limits measured using CDF Run II data. These limits provide important test of the interaction of the photon and the Z boson. / Dissertation

In this thesis, fundamental questions about the nature of the solvent/counter-ion region of x-ray crystal structures are raised. The ambiguity in the identity and occupancy of the molecular and atomic species in this region is explored experimentally. Anomalous scattering is proposed as a possible method for resolving this ambiguity. To this effect, the properties of rubidium I and thallium I are compared and contrasted to each other and to other group I metals. Finally, the structures of two modified B-DNA dodecamers are determined to explore the effect of monovalent cations on B-DNA structure. The modifications in these structures harbor tethered cations that are covalently linked to the DNA in the major groove. In one structure, the tethered cation causes axial bending of the DNA molecule, while in the second structure the molecule remains linear. We posit that the discrepancy between the two structures is due to lattice packing forces. In addition, we show evidence for the displacement of thallium I cations from the major groove of the bent structure.