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Articles 1 - 30 of 32
Full-Text Articles in Physical Sciences and Mathematics
The Clustering Of Galaxies In The Sdss-Iii Baryon Oscillation Spectroscopic Survey: Weighing The Neutrino Mass Using The Galaxy Power Spectrum Of The Cmass Sample, Gong-Bo Zhao, Shun Saito, For Full List Of Authors, See Publisher's Website.
The Clustering Of Galaxies In The Sdss-Iii Baryon Oscillation Spectroscopic Survey: Weighing The Neutrino Mass Using The Galaxy Power Spectrum Of The Cmass Sample, Gong-Bo Zhao, Shun Saito, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We measure the sum of the neutrino particle masses using the three-dimensional galaxy power spectrum of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey Data Release 9 the constant MASS (CMASS) galaxy sample. Combined with the cosmic microwave background, supernova and additional baryonic acoustic oscillation data, we find upper 95 per cent confidence limits (CL) of the neutrino mass ∑mν < 0.340 eV within a flat Λ cold dark matter (ΛCDM) background, and ∑mν< 0.821 eV, assuming a more general background cosmological model. The number of neutrino species is measured to be Neff = 4.308 ± 0.794 and 4.032+0.870 -0.894 for these two cases, respectively. We study and quantify the effect of several factors on the neutrino measurements, including the galaxy power spectrum bias model, the …
Light Sea Fermions In Electron-Proton And Muon-Proton Interactions, Ulrich D. Jentschura
Light Sea Fermions In Electron-Proton And Muon-Proton Interactions, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The proton radius conundrum [Pohl, Nature 466, 213 (2010)NATUAS0028-083610. 1038/nature09250 and Antognini, Science 339, 417 (2013)SCIEAS0036-807510.1126/ science.1230016] highlights the need to revisit any conceivable sources of electron-muon nonuniversality in lepton-proton interactions within the standard model. Superficially, a number of perturbative processes could appear to lead to such a nonuniversality. One of these is a coupling of the scattered electron into an electronic vacuum-polarization loop as opposed to a muonic one in the photon exchange of two valence quarks, which is present only for electron projectiles as opposed to muon projectiles. However, we show that this effect actually is part of …
Experimental And Theoretical Cross Sections For Molecular-Frame Electron-Impact Excitation-Ionization Of D₂, Julian C A Lower, Esam S M Ali, Susan M. Bellm, Erich Weigold, Allison L. Harris, Chuangang Ning, Don H. Madison
Experimental And Theoretical Cross Sections For Molecular-Frame Electron-Impact Excitation-Ionization Of D₂, Julian C A Lower, Esam S M Ali, Susan M. Bellm, Erich Weigold, Allison L. Harris, Chuangang Ning, Don H. Madison
Physics Faculty Research & Creative Works
We present both experimental and theoretical results for the dissociative ionization of D2 molecules induced by electron impact. Cross sections are determined in the molecular frame and are fully differential in the energies and emission angles of the dissociation fragments. Transitions are considered from the X1Σg+ electronic ground state of D2 to the 2sσg, 2pπu and 2pσu excited states of D2+. The experimental results are compared to calculations performed within the molecular four-body distorted-wave framework to describe the multicenter nature of the scattering process. The cross sections …
Search For Long-Lived Gravitational-Wave Transients Coincident With Long Gamma-Ray Bursts, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Long-Lived Gravitational-Wave Transients Coincident With Long Gamma-Ray Bursts, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Long gamma-ray bursts (GRBs) have been linked to extreme core-collapse supernovae from massive stars. Gravitational waves (GW) offer a probe of the physics behind long GRBs. We investigate models of long-lived (∼10-1000 s) GW emission associated with the accretion disk of a collapsed star or with its protoneutron star remnant. Using data from LIGO's fifth science run, and GRB triggers from the Swift experiment, we perform a search for unmodeled long-lived GW transients. Finding no evidence of GW emission, we place 90% confidence-level upper limits on the GW fluence at Earth from long GRBs for three waveforms inspired by a …
Directed Search For Continuous Gravitational Waves From The Galactic Center, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Directed Search For Continuous Gravitational Waves From The Galactic Center, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO's fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first-order spindown values down to -7.86 x 10-8 Hz/s at the highest frequency. No gravitational waves were detected. The 90% …
Plasmonic Scaling Of Superconducting Metamaterials, Cihan Kurter, John A. Abrahams, Gennady Shvets, Steven Mark Anlage
Plasmonic Scaling Of Superconducting Metamaterials, Cihan Kurter, John A. Abrahams, Gennady Shvets, Steven Mark Anlage
Physics Faculty Research & Creative Works
Superconducting metamaterials are utilized to study the approach to the plasmonic limit simply by tuning temperature to modify the superfluid density, and thus the superfluid plasma frequency. We examine the persistence of artificial magnetism in a metamaterial made with superconductors in the plasmonic limit, and compare to the electromagnetic behavior of normal metals as a function of frequency as the plasma frequency is approached from below. Spiral-shaped Nb thin film meta-atoms of scaled dimensions are employed to explore the plasmonic behavior in these superconducting metamaterials, and the scaling condition allows extraction of the temperature dependent superfluid density, which is found …
Phases And Phase Transitions In Disordered Quantum Systems, Thomas Vojta
Phases And Phase Transitions In Disordered Quantum Systems, Thomas Vojta
Physics Faculty Research & Creative Works
These lecture notes give a pedagogical introduction to phase transitions in disordered quantum systems and to the exotic Griffiths phases induced in their vicinity. We first review some fundamental concepts in the physics of phase transitions. We then derive criteria governing under what conditions spatial disorder or randomness can change the properties of a phase transition. After introducing the strong-disorder renormalization group method, we discuss in detail some of the exotic phenomena arising at phase transitions in disordered quantum systems. These include infinite-randomness criticality, rare regions and quantum Griffiths singularities, as well as the smearing of phase transitions. We also …
Measuring The Angle-Dependent Photoionization Cross Section Of Nitrogen Using High-Harmonic Generation, Xiaoming Ren, Varun Makhija, Anh-Thu Le, Jan Troß, Sudipta Mondal, Cheng Jin, Vinod Kumarappan, Carlos A. Trallero-Herrero
Measuring The Angle-Dependent Photoionization Cross Section Of Nitrogen Using High-Harmonic Generation, Xiaoming Ren, Varun Makhija, Anh-Thu Le, Jan Troß, Sudipta Mondal, Cheng Jin, Vinod Kumarappan, Carlos A. Trallero-Herrero
Physics Faculty Research & Creative Works
We exploit the relationship between high harmonic generation (HHG) and the molecular photorecombination dipole to extract the molecular-frame differential photoionization cross section (PICS) in the extreme ultraviolet (XUV) for molecular nitrogen. A shape resonance and a Cooper-type minimum are reflected in the pump-probe time delay measurements of different harmonic orders, where high-order rotational revivals are observed in N₂. We observe the energy- and angle-dependent Cooper minimum and shape resonance directly in the laboratory-frame HHG yield by achieving a high degree of alignment, [SEE FORMULA IN ABSTRACT cos2 θ] 0.8. The interplay between PICS and rotational revivals is confirmed by simulations …
Parameter Estimation For Compact Binary Coalescence Signals With The First Generation Gravitational-Wave Detector Network, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Parameter Estimation For Compact Binary Coalescence Signals With The First Generation Gravitational-Wave Detector Network, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and …
Oscillons And Oscillating Kinks In The Abelian-Higgs Model, V. Achilleos, F. K. Diakonos, D. J. Frantzeskakis, Garyfallia C. Katsimiga, X. N. Maintas, E. Manousakis, C. E. Tsagkarakis, A. Tsapalis
Oscillons And Oscillating Kinks In The Abelian-Higgs Model, V. Achilleos, F. K. Diakonos, D. J. Frantzeskakis, Garyfallia C. Katsimiga, X. N. Maintas, E. Manousakis, C. E. Tsagkarakis, A. Tsapalis
Physics Faculty Research & Creative Works
We study the classical dynamics of the Abelian Higgs model employing an asymptotic multiscale expansion method, which uses the ratio of the Higgs to the gauge field amplitudes as a small parameter. We derive an effective nonlinear Schrödinger equation for the gauge field, and a linear equation for the scalar field containing the gauge field as a nonlinear source. This equation is used to predict the existence of oscillons and oscillating kinks for certain regimes of the ratio of the Higgs to the gauge field masses. Results of direct numerical simulations are found to be in very good agreement with …
Postcollision Effects In Target Ionization By Ion Impact At Large Momentum Transfer, Michael Schulz, B. Najjari, Alexander B. Voitkiv, Katharina R. Schneider, Xincheng Wang, Aaron C. Laforge, Renate Hubele, Johannes Goullon, Natalia Ferreira, Aditya H. Kelkar, Manfred Grieser, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer
Postcollision Effects In Target Ionization By Ion Impact At Large Momentum Transfer, Michael Schulz, B. Najjari, Alexander B. Voitkiv, Katharina R. Schneider, Xincheng Wang, Aaron C. Laforge, Renate Hubele, Johannes Goullon, Natalia Ferreira, Aditya H. Kelkar, Manfred Grieser, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer
Physics Faculty Research & Creative Works
We have measured and calculated fully differential cross sections for target ionization in 16-MeV O7++He and 24-MeV O8++Li collisions. As in previous studies, in the case of the He target we observe a pronounced forward shift in the angular distribution of the electrons relative to the direction of the momentum transfer q at small q (q < 1 a.u.). An unexpected result is that we also find a strong forward shift at large q (q > 2 a.u.), while at intermediate q this shift becomes very weak or even turns into a backward shift. For the Li target, in contrast, the forward shift monotonically increases with increasing q. These observations are qualitatively reproduced by our calculations. …
High-Order-Harmonic Generation From Molecular Isomers With Midinfrared Intense Laser Pulses, Anh-Thu Le, R. R. Lucchese, C. D. Lin
High-Order-Harmonic Generation From Molecular Isomers With Midinfrared Intense Laser Pulses, Anh-Thu Le, R. R. Lucchese, C. D. Lin
Physics Faculty Research & Creative Works
We present theoretical calculations of high-order-harmonic generation (HHG) from stereoisomers of 1,2-dichloroethylene (C₂H₂Cl₂) and 2-butene (C₄H₈) based on the quantitative rescattering theory. Our results show that the HHG spectra from these cis and trans isomers with intense midinfrared laser pulses are clearly distinguishable, even when the molecules are randomly oriented, in good agreement with the recent experiments by Wonget al. [Phys. Rev. A 84, 051403(R) (2011)]. We found that the angle-averaged tunneling ionization yields and photoionization cross sections from the cis and trans isomers for both molecules are nearly identical. The origin of the differences in HHG spectra is traced …
Nonrelativistic Limit Of The Dirac-Schwarzschild Hamiltonian: Gravitational Zitterbewegung And Gravitational Spin-Orbit Coupling, Ulrich D. Jentschura, J. H. Noble
Nonrelativistic Limit Of The Dirac-Schwarzschild Hamiltonian: Gravitational Zitterbewegung And Gravitational Spin-Orbit Coupling, Ulrich D. Jentschura, J. H. Noble
Physics Faculty Research & Creative Works
We investigate the nonrelativistic limit of the gravitationally coupled Dirac equation via a Foldy-Wouthuysen transformation. The relativistic correction terms have immediate and obvious physical interpretations in terms of a gravitational Zitterbewegung and a gravitational spin-orbit coupling. We find no direct coupling of the spin vector to the gravitational force, which would otherwise violate parity. The particle-antiparticle symmetry described recently by one of us is verified on the level of the perturbative corrections accessed by the Foldy-Wouthuysen transformation. The gravitational corrections to the electromagnetic transition current are calculated.
Modification Of Smeared Phase Transitions By Spatial Disorder Correlations, David Nozadze, Christopher Svoboda, Fawaz Hrahsheh, Thomas Vojta
Modification Of Smeared Phase Transitions By Spatial Disorder Correlations, David Nozadze, Christopher Svoboda, Fawaz Hrahsheh, Thomas Vojta
Physics Faculty Research & Creative Works
Phase transitions in disordered systems can be smeared if rare spatial regions develop true static order while the bulk system is in the disordered phase. Here, we study the effects of spatial disorder correlations on such smeared phase transitions. The behaviors of observables are determined within optimal fluctuation theory. We show that even short-range correlations can qualitatively modify smeared phase transitions. For positive correlations (like impurity atoms attract each other), the order parameter is enhanced, while it is suppressed for repulsive correlations (like atoms repel each other). We use computer simulations to generate various types of disorder correlations, and to …
Structural And Magnetic Properties Of La₀.₇Sr₀.₃Mn₁₋ₓniₓo₃ (X ≤ 0.4), Thomas F. Creel, Jinbo Yang, Mehmet Kahveci, Satish K. Malik, Sylvio Quezado, Oran Allan Pringle, William B. Yelon, William Joseph James
Structural And Magnetic Properties Of La₀.₇Sr₀.₃Mn₁₋ₓniₓo₃ (X ≤ 0.4), Thomas F. Creel, Jinbo Yang, Mehmet Kahveci, Satish K. Malik, Sylvio Quezado, Oran Allan Pringle, William B. Yelon, William Joseph James
Physics Faculty Research & Creative Works
We have studied the structural and magnetic properties of La0.7Sr0.3Mn1-xNixO3 (x = 0.05, 0.1, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. Our data consist of neutron (γ = 1.479Å) and x-ray (γ = 1.5481Å; Cu Kα) powder diffraction and magnetization measurements. We previously suggested these systems transition from ferromagnetic to antiferromagnetic ordering with the intermediate concentrations containing coexisting domains of ferromagnetically and antiferromagnetically ordered states. Upon further detailed examination, we find that the samples are homogeneous and that neutron data can be fitted to a …
Erratum: Gravitationally Coupled Dirac Equation For Antimatter (Physical Review A (2013) 87 (032101) Doi:10.1103/Physreva.87.032101), Ulrich D. Jentschura
Erratum: Gravitationally Coupled Dirac Equation For Antimatter (Physical Review A (2013) 87 (032101) Doi:10.1103/Physreva.87.032101), Ulrich D. Jentschura
Physics Faculty Research & Creative Works
No abstract provided.
A Dynamical (E,2e) Investigation Of The Structurally Related Cyclic Ethers Tetrahydrofuran, Tetrahydropyran, And 1,4-Dioxane, J. D. Builth-Williams, Susan M. Bellm, Luca Chiari, Penny A. Thorn, Darryl B. Jones, Hari Chaluvadi, Don H. Madison, Chuangang Ning, B. Lohmann, Gabriel Da Silva, Michael J. Brunger
A Dynamical (E,2e) Investigation Of The Structurally Related Cyclic Ethers Tetrahydrofuran, Tetrahydropyran, And 1,4-Dioxane, J. D. Builth-Williams, Susan M. Bellm, Luca Chiari, Penny A. Thorn, Darryl B. Jones, Hari Chaluvadi, Don H. Madison, Chuangang Ning, B. Lohmann, Gabriel Da Silva, Michael J. Brunger
Physics Faculty Research & Creative Works
Triple differential cross section measurements for the electron-impact ionization of the highest occupied molecular orbitals of tetrahydropyran and 1,4-dioxane are presented. For each molecule, experimental measurements were performed using the (e,2e) technique in asymmetric coplanar kinematics with an incident electron energy of 250 eV and an ejected electron energy of 20 eV. With the scattered electrons being detected at -5°, the angular distributions of the ejected electrons in the binary and recoil regions were observed. These measurements are compared with calculations performed within the molecular 3-body distorted wave model. Here, reasonable agreement was observed between the theoretical model and the …
Quantitative Rescattering Theory Of High-Order Harmonic Generation For Polyatomic Molecules, Anh-Thu Le, R. R. Lucchese, C. D. Lin
Quantitative Rescattering Theory Of High-Order Harmonic Generation For Polyatomic Molecules, Anh-Thu Le, R. R. Lucchese, C. D. Lin
Physics Faculty Research & Creative Works
We report applications of the quantitative rescattering theory (QRS) for calculation of high-order-harmonic generation (HHG) from polyatomic molecules in ultrashort linearly polarized intense laser pulses, using the example of the CCl₄ molecule. In particular, we present a detailed analysis and a treatment for the phase of the electron returning wave packet, which recollides with the parent molecular ion to emit high-energy photons. Our results show that Cooper-type minimum structures in the molecular photoionization cross section lead to quite distinguishable minima in the HHG spectra, even for unaligned polyatomic molecules.
Low Energy (E,2e) Coincidence Studies Of Nh₃: Results From Experiment And Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, James Colgan, Don H. Madison
Low Energy (E,2e) Coincidence Studies Of Nh₃: Results From Experiment And Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, James Colgan, Don H. Madison
Physics Faculty Research & Creative Works
Experimental and theoretical triple differential cross sections (TDCS) from ammonia are presented in the low energy regime with outgoing electron energies from 20 eV down to 1.5 eV. Ionization measurements from the 3a1, 1e1, and 2a1 molecular orbitals were taken in a coplanar geometry. Data from the 3a1 and 1e1 orbitals were also obtained in a perpendicular plane geometry. The data are compared to predictions from the distorted wave Born approximation and molecular-three-body distorted wave models. The cross sections for the 3a1 and 1e1 orbitals that have p-like character were found …
Interplay Between Localization And Absorption In Disordered Waveguides, Alexey Yamilov, Ben Payne
Interplay Between Localization And Absorption In Disordered Waveguides, Alexey Yamilov, Ben Payne
Physics Faculty Research & Creative Works
This work presents results of ab-initio simulations of continuous wave transport in disordered absorbing waveguides. Wave interference effects cause deviations from diffusive picture of wave transport and make the diffusion coefficient position- and absorption-dependent. As a consequence, the true limit of a zero diffusion coefficient is never reached in an absorbing random medium of infinite size, instead, the diffusion coefficient saturates at some finite constant value. Transition to this absorption-limited diffusion exhibits a universality which can be captured within the framework of the self-consistent theory (SCT) of localization. The results of this work (i) justify use of SCT in analyses …
Compact Object Coalescence Rate Estimation From Short Gamma-Ray Burst Observations, Carlo Enrico Petrillo, Alexander Dietz, Marco Cavaglia
Compact Object Coalescence Rate Estimation From Short Gamma-Ray Burst Observations, Carlo Enrico Petrillo, Alexander Dietz, Marco Cavaglia
Physics Faculty Research & Creative Works
Recent observational and theoretical results suggest that short-duration gamma-ray bursts (SGRBs) originate from the merger of compact binary systems of two neutron stars or a neutron star and a black hole. The observation of SGRBs with known redshifts allows astronomers to infer the merger rate of these systems in the local universe. We use data from the SWIFT satellite to estimate this rate to be in the range ∼500-1500 Gpc-3 yr-1. This result is consistent with earlier published results which were obtained through alternative approaches. We estimate the number of coincident observations of gravitational-wave signals with SGRBs …
Phonon Lifetime Investigation Of Anharmonicity And Thermal Conductivity Of Uo₂ By Neutron Scattering And Theory, Judy W. Pang, William J. Buyers, Aleksandr V. Chernatynskiy, Mark D. Lumsden, Bennett C. Larson, Simon R. Phillpot
Phonon Lifetime Investigation Of Anharmonicity And Thermal Conductivity Of Uo₂ By Neutron Scattering And Theory, Judy W. Pang, William J. Buyers, Aleksandr V. Chernatynskiy, Mark D. Lumsden, Bennett C. Larson, Simon R. Phillpot
Physics Faculty Research & Creative Works
Inelastic neutron scattering measurements of individual phonon lifetimes and dispersion at 295 and 1200 K have been used to probe anharmonicity and thermal conductivity in UO2. They show that longitudinal optic phonon modes carry the largest amount of heat, in contrast to past simulations and that the total conductivity demonstrates a quantitative correspondence between microscopic and macroscopic phonon physics. We have further performed first-principles simulations for UO2 showing semiquantitative agreement with phonon lifetimes at 295 K, but larger anharmonicity than measured at 1200 K.
Comment On "Singly Ionizing 100-Mev/Amu C⁶⁺+He Collisions With Small Momentum Transfer", Michael Schulz, Robert Moshammer, Daniel Fischer, Joachim Hermann Ullrich
Comment On "Singly Ionizing 100-Mev/Amu C⁶⁺+He Collisions With Small Momentum Transfer", Michael Schulz, Robert Moshammer, Daniel Fischer, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
In a recent article, Kouzakov suggested that experimental resolution effects can be responsible for discrepancies between measured and calculated fully differential cross sections for the ionization of helium by fast C6+ impact. They further asserted that projectile-coherence effects have no influence on the measured cross sections. In this Comment, we reiterate that the experimental resolution can only explain part of the discrepancies. Furthermore, we note that the conclusion regarding the role of projectile coherence neglects potential interference between first- and higher-order transition amplitudes.
Polarization And Interference Effects In Ionization Of Li By Ion Impact, Renate Hubele, Aaron C. Laforge, Michael Schulz, Johannes Goullon, Xincheng Wang, B. Najjari, Natalia Ferreira, Manfred Grieser, Vitor L B D De Jesus, Robert Moshammer, Katharina R. Schneider, Alexander B. Voitkiv, Daniel Fischer
Polarization And Interference Effects In Ionization Of Li By Ion Impact, Renate Hubele, Aaron C. Laforge, Michael Schulz, Johannes Goullon, Xincheng Wang, B. Najjari, Natalia Ferreira, Manfred Grieser, Vitor L B D De Jesus, Robert Moshammer, Katharina R. Schneider, Alexander B. Voitkiv, Daniel Fischer
Physics Faculty Research & Creative Works
We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV O8+ impact. The data for ionization from the 2s and 2p states look qualitatively different from each other and from 1s ionization of He. For ionization from the 2p state, to which in our study the mL=-1 substate predominantly contributes, we observe orientational dichroism and for 2s ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function.
Role Of Projectile Coherence In Close Heavy Ion-Atom Collisions, Katharina R. Schneider, Michael Schulz, Xincheng Wang, Aditya H. Kelkar, Manfred Grieser, Claude Krantz, Joachim Hermann Ullrich, Robert Moshammer, Daniel Fischer
Role Of Projectile Coherence In Close Heavy Ion-Atom Collisions, Katharina R. Schneider, Michael Schulz, Xincheng Wang, Aditya H. Kelkar, Manfred Grieser, Claude Krantz, Joachim Hermann Ullrich, Robert Moshammer, Daniel Fischer
Physics Faculty Research & Creative Works
We have measured fully differential cross sections for single ionization and transfer ionization (TI) in 16 MeV O7++He collisions. The impact parameters mostly contributing to single ionization are about an order of magnitude larger than for TI. Therefore, the projectile beam was much more coherent for the latter compared to the former process. The measured data suggest that, as a result, TI is significantly affected by interference effects which are not present in single ionization.
Theoretical Study Of The Compton Effect With Correlated Three-Photon Emission: From The Differential Cross Section To High-Energy Triple-Photon Entanglement, Erik Loetstedt, Ulrich D. Jentschura
Theoretical Study Of The Compton Effect With Correlated Three-Photon Emission: From The Differential Cross Section To High-Energy Triple-Photon Entanglement, Erik Loetstedt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The three-photon Compton effect is studied. An incoming photon undergoes triple scattering off a free electron, which leads to the emission of three entangled photons. We investigate the properties of both the total cross section, assuming a low-energy cutoff for the detected photons, and the differential cross section. Particular emphasis is laid on evaluating polarization-resolved cross sections. The entanglement of the final three-photon state is analyzed.
Gravitationally Coupled Dirac Equation For Antimatter, Ulrich D. Jentschura
Gravitationally Coupled Dirac Equation For Antimatter, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The coupling of antimatter to gravity is of general interest because of conceivable cosmological consequences ("surprises") related to dark energy and the cosmological constant. Here, we revisit the derivation of the gravitationally coupled Dirac equation and find that the prefactor of a result given previously by Brill and Wheeler [Rev. Mod. Phys. 29, 465 (1957)] for the affine connection matrix is in need of a correction. We also discuss the conversion of the curved-space Dirac equation from the so-called "East-Coast" to the "West-Coast" convention, in order to bring the gravitationally coupled Dirac equation to a form where it can easily …
Imaging The Anisotropic Nonlinear Meissner Effect In Nodal Yba ₂Cu₃O7-Δ Thin-Film Superconductors, Alexander P. Zhuravel, Behnood G. Ghamsari, Cihan Kurter, Philipp Jung, Stephen K. Remillard, John A. Abrahams, Alexander V. Lukashenko, Alexey V. Ustinov, Steven Mark Anlage
Imaging The Anisotropic Nonlinear Meissner Effect In Nodal Yba ₂Cu₃O7-Δ Thin-Film Superconductors, Alexander P. Zhuravel, Behnood G. Ghamsari, Cihan Kurter, Philipp Jung, Stephen K. Remillard, John A. Abrahams, Alexander V. Lukashenko, Alexey V. Ustinov, Steven Mark Anlage
Physics Faculty Research & Creative Works
We have directly imaged the anisotropic nonlinear Meissner effect in an unconventional superconductor through the nonlinear electrodynamic response of both (bulk) gap nodes and (surface) Andreev bound states. A superconducting thin film is patterned into a compact self-resonant spiral structure, excited near resonance in the radio-frequency range, and scanned with a focused laser beam perturbation. At low temperatures, direction-dependent nonlinearities in the reactive and resistive properties of the resonator create photoresponse that maps out the directions of nodes, or of bound states associated with these nodes, on the Fermi surface of the superconductor. The method is demonstrated on the nodal …
Einstein@Home All-Sky Search For Periodic Gravitational Waves In Ligo S5 Data, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Einstein@Home All-Sky Search For Periodic Gravitational Waves In Ligo S5 Data, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50,1 190] Hz and with frequency derivative range of ∼[-20,1.1] x 10-10 Hz s-1 for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we …
Picturing Electron Capture To The Continuum In The Transfer Ionization Of Intermediate-Energy He²⁺ Collisions With Argon, Ruitian Zhang, Xinwen Ma, Shaofeng Zhang, Xiaolong Zhu, Susmitha Akula, Don H. Madison, Bingsheng Li, Dongbin Qian, Wentian Feng, Dalong Guo, Huiping Liu, Shuncheng Yan, Pengju Zhang, Shenyue Xu, Ximeng Chen
Picturing Electron Capture To The Continuum In The Transfer Ionization Of Intermediate-Energy He²⁺ Collisions With Argon, Ruitian Zhang, Xinwen Ma, Shaofeng Zhang, Xiaolong Zhu, Susmitha Akula, Don H. Madison, Bingsheng Li, Dongbin Qian, Wentian Feng, Dalong Guo, Huiping Liu, Shuncheng Yan, Pengju Zhang, Shenyue Xu, Ximeng Chen
Physics Faculty Research & Creative Works
Electron emission occurring in transfer ionization for He2+ collisions with argon has been investigated using cold target recoil ion momentum spectroscopy. The double differential cross sections for electron capture to the continuum of the projectile (cusp-shaped electrons) are presented for collision energies from 17.5 to 75 keV/u. For an energy of 30 keV/u, we find a maximum in the experimental ratio of the cusp-shaped electron yield to the total electron yield. This result is explained in terms of the velocity matching between the projectile ion and the electron initially bound to the target. One of the important issues for …