Open Access. Powered by Scholars. Published by Universities.®

Elementary Particles and Fields and String Theory Commons

Open Access. Powered by Scholars. Published by Universities.®

690 Full-Text Articles 669 Authors 34280 Downloads 49 Institutions

All Articles in Elementary Particles and Fields and String Theory

Faceted Search

690 full-text articles. Page 1 of 23.

Imaging Electronic Motions By Ultrafast Electron Diraction, Hua-Chieh Shao, Anthony F. Starace 2017 University of Nebraska-Lincoln

Imaging Electronic Motions By Ultrafast Electron Diraction, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

Recently ultrafast electron diraction and microscopy have reached unprecedented temporal resolution, and transient structures with atomic precision have been observed in various reactions. It is anticipated that these extraordinary advances will soon allow direct observation of electronic motions during chemical reactions. We therefore performed a series of theoretical investigations and simulations to investigate the imaging of electronic motions in atoms and molecules by ultrafast electron diraction. Three prototypical electronic motions were considered for hydrogen atoms. For the case of a breathing mode, the electron density expands and contracts periodically, and we show that the time-resolved scattering intensities re ect such ...


Energy-Resolved Coherent Diffraction From Laser-Driven Electronic Motion In Atoms, Hua-Chieh Shao, Anthony F. Starace 2017 University of Nebraska-Lincoln

Energy-Resolved Coherent Diffraction From Laser-Driven Electronic Motion In Atoms, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

We investigate theoretically the use of energy-resolved ultrafast electron diffraction to image laser-driven electronic motion in atoms. A chirped laser pulse is used to transfer the valence electron of the lithium atom from the ground state to the first excited state. During this process, the electronic motion is imaged by 100-fs and 1-fs electron pulses in energy-resolved diffraction measurements. Simulations show that the angle-resolved spectra reveal the time evolution of the energy content and symmetry of the electronic state. The time-dependent diffraction patterns are further interpreted in terms of the momentum transfer. For the case of incident 1-fs electron pulses ...


Ionization Enhancement And Suppression By Phase-Locked Ultrafast Pulse Pairs, David B. Foote, Y. Lin, Liang-Wen Pi, Jean Marcel Ngoko Djiokap, Anthony F. Starace, W. T. Hill 2017 University of Maryland at College Park

Ionization Enhancement And Suppression By Phase-Locked Ultrafast Pulse Pairs, David B. Foote, Y. Lin, Liang-Wen Pi, Jean Marcel Ngoko Djiokap, Anthony F. Starace, W. T. Hill

Anthony F. Starace Publications

We present the results of a study of ionization of Xe atoms by a pair of phase-locked pulses, which is characterized by interference produced by the twin peaks. Two types of interference are considered: ordinary optical interference, which changes the intensity of the composite pulse and thus the ion yield, and a quantum interference, in which the excited electron wave packets interfere. We use the measured Xe+ yield as a function of the temporal delay and/or relative phase between the peaks to monitor the interferences and compare their relative strengths. We model the interference with a pulse intensity function ...


Adiabatic-Limit Coulomb Factors For Photoelectron And High-Order-Harmonic Spectra, M. V. Frolov, N. L. Manakov, A. A. Minina, S. V. Popruzhenko, Anthony F. Starace 2017 Voronezh State University, Russia

Adiabatic-Limit Coulomb Factors For Photoelectron And High-Order-Harmonic Spectra, M. V. Frolov, N. L. Manakov, A. A. Minina, S. V. Popruzhenko, Anthony F. Starace

Anthony F. Starace Publications

A momentum-dependent Coulomb factor in the probability for nonlinear ionization of atoms by a strong low-frequency laser field is calculated analytically in the adiabatic approximation. Expressions for this Coulomb factor, valid for an arbitrary laser pulse waveform, are obtained and analyzed in detail for the cases of linear and circular polarizations. The dependence of the Coulomb factor on the photoelectron momentum is shown to be significant in both cases. Using a similar technique, the Coulomb factor for emission of high-order harmonics by an atom in a bichromatic laser field is also calculated. In contrast to the case of a single-frequency ...


Thermomechanical Properties Of Aluminium Heaters To Test The Compact Muon Solenoid Cooling System For Phase Two Upgrade, Sandra Jimena González, Timothy Matthew Jones 2017 Universidad de Los Andes - Colombia

Thermomechanical Properties Of Aluminium Heaters To Test The Compact Muon Solenoid Cooling System For Phase Two Upgrade, Sandra Jimena González, Timothy Matthew Jones

The Summer Undergraduate Research Fellowship (SURF) Symposium

The main objectives of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider are precision studies of the Standard Model of Particle Physics and the discovery of physics beyond it. To meet that, it is essential for the CMS detector to function at the highest efficiency for detecting subatomic particles within various technical constraints. In particular, the readout chips of the Pixel Tracker sub-detector produce significant heat and must be kept at -10 °C to ensure optimal performance and reduce cumulative damage in the high radiation environment. Thus, it is necessary to design a cooling system to extract ...


Machine Learning In Xenon1t Analysis, Dillon A. Davis, Rafael F. Lang, Darryl P. Masson 2017 Purdue University - North Central Campus

Machine Learning In Xenon1t Analysis, Dillon A. Davis, Rafael F. Lang, Darryl P. Masson

The Summer Undergraduate Research Fellowship (SURF) Symposium

In process of analyzing large amounts of quantitative data, it can be quite time consuming and challenging to uncover populations of interest contained amongst the background data. Therefore, the ability to partially automate the process while gaining additional insight into the interdependencies of key parameters via machine learning seems quite appealing. As of now, the primary means of reviewing the data is by manually plotting data in different parameter spaces to recognize key features, which is slow and error prone. In this experiment, many well-known machine learning algorithms were applied to a dataset to attempt to semi-automatically identify known populations ...


Kinematical Vortices In Double Photoionization Of Helium By Attosecond Pulses, Jean Marcel Ngoko Djiokap, A. V. Meremianin, N. L. Manakov, S. X. Hu, L. B. Madsen, Anthony F. Starace 2017 University of Nebraska-Lincoln

Kinematical Vortices In Double Photoionization Of Helium By Attosecond Pulses, Jean Marcel Ngoko Djiokap, A. V. Meremianin, N. L. Manakov, S. X. Hu, L. B. Madsen, Anthony F. Starace

Anthony F. Starace Publications

Two-armed helical vortex structures are predicted in the two-electron momentum distributions produced in double photoionization (DPI) of the He atom by a pair of time-delayed elliptically polarized attosecond pulses with opposite helicities. These predictions are based upon both a first-order perturbation theory analysis and numerical solutions of the two-electron, time-dependent Schrödinger equation in six spatial dimensions. The helical vortex structures originate from Ramsey interference of a pair of ionized two-electron wave packets, each having a total angular momentum of unity, and appear in the sixfold differential DPI probability distribution for any energy partitioning between the two electrons. The vortex structures ...


Searching For Heavy Photons With Detached Vertices In The Heavy Photon Search Experiment, Holly Szumila-Vance 2017 Old Dominion University

Searching For Heavy Photons With Detached Vertices In The Heavy Photon Search Experiment, Holly Szumila-Vance

Physics Theses & Dissertations

The Jefferson Lab Heavy Photon Search (HPS) experiment is searching for a hypothetical massive particle called the heavy photon which could mediate a dark electromagnetic-type force. If heavy photons kinetically mix with Standard Model photons, they may be radiated by electrons scattering from a heavy nucleus and then decay to e+e- pairs. HPS uniquely searches for heavy photons that either decay at the target or a measurable distance after. The experiment utilizes a silicon vertex tracker (SVT) for momentum and vertex reconstruction, together with an electromagnetic calorimeter for measuring particle energies and triggering events. The HPS experiment took its ...


Higher-Twist Corrections To Gluon Tmd Factorization, I. Balitsky, A. Tarasov 2017 Old Dominion University

Higher-Twist Corrections To Gluon Tmd Factorization, I. Balitsky, A. Tarasov

Physics Faculty Publications

We calculate power corrections to TMD factorization for particle production by gluon-gluon fusion in hadron-hadron collisions.


First Results From Rhic-Phenix, Tarun Kanti Ghosh, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, et al. 2017 Vanderbilt University

First Results From Rhic-Phenix, Tarun Kanti Ghosh, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, Et Al.

Craig Ogilvie

The PHENIX experiment consists of a large detector system located at the newly commissioned relativistic heavy ion collider (RHIC) at the Brookhaven National Laboratory. The primary goal of the PHENIX experiment is to look for signatures of the QCD prediction of a deconfined high-energy-density phase of nuclear matter quark gluon plasma. PHENIX started data taking for Au+Au collisions at √sNN = 130 GeV in June 2000. The signals from the beam-beam counter (BBC) and zero degree calorimeter (ZDC) are used to determine the centrality of the collision. A Glauber model reproduces the ZDC spectrum reasonably well to determine the participants ...


Phenix Upgrade: Novel Stripixel Detector For Heavy Quark Detection And Proton Spin Structure Measurements At Rhic Energies, R. Nouicer, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, et al. 2017 Brookhaven National Laboratory

Phenix Upgrade: Novel Stripixel Detector For Heavy Quark Detection And Proton Spin Structure Measurements At Rhic Energies, R. Nouicer, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al.

Craig Ogilvie

New design of silicon stripixel sensor has been developed at BNL for PHENIX upgrade. The sensor is a single-sided, DC-coupled, two-dimensional position sensitive device with good position resolution. This design is simpler for sensor fabrication and signal processing than the conventional double-sided strip sensor. HPK has produced pre-production stripixel sensors with thickness of 625 μm. The quality assurance tests show that the very low leakage current 0.12 nA per strip allows the use of the SVX4 chip. A long term stability test shows that the leakage current is stable over a long period of time. The study of the ...


Deuteron And Antideuteron Production In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, et al. 2017 Brookhaven National Laboratory

Deuteron And Antideuteron Production In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al.

Craig Ogilvie

The production of deuterons and antideuterons in the transverse momentum range 1.1 < p(T)< 4.3 GeV/c at midrapidity in Au+Au collisions at root s(NN) = 200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of p(T), which is consistent with an expanding collision zone. Comparing (anti)proton yields, (p) over bar /p = 0.73 +/- 0.01, with (anti)deuteron ...


Double Helicity Asymmetry In Inclusive Midrapidity Pi(0) Production For Polarized P+P Collisions At Root S=200 Gev, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, et al. 2017 Brookhaven National Laboratory

Double Helicity Asymmetry In Inclusive Midrapidity Pi(0) Production For Polarized P+P Collisions At Root S=200 Gev, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al.

Craig Ogilvie

We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a ...


Centrality Dependence Of Pi(+/-), K-+/-, P, And (P)Over-Bar Production From Root(Nn)-N-S = 130 Gev Au+Au Collisions At Rhic, K. Adcox, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, et al. 2017 Vanderbilt University

Centrality Dependence Of Pi(+/-), K-+/-, P, And (P)Over-Bar Production From Root(Nn)-N-S = 130 Gev Au+Au Collisions At Rhic, K. Adcox, Sergey Belikov, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Athanasios Petridis, Marzia Rosati, F. K. Wohn, Et Al.

Craig Ogilvie

Identified pi(+/-), K+/-, p, and (p) over bar transverse momentum spectra at midrapidity in root s(NN) = 130 GeV Au + Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K+/-, p, and (p) over bar yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta ...


Centrality Dependence Of Pi(0) And Eta Production At Large Transverse Momentum In Root S(Nn) = 200 Gev D+Au Collisions, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, et al. 2017 Brookhaven National Laboratory

Centrality Dependence Of Pi(0) And Eta Production At Large Transverse Momentum In Root S(Nn) = 200 Gev D+Au Collisions, S. S. Adler, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al.

Craig Ogilvie

The dependence of transverse momentum spectra of neutral pions and eta mesons with p(T) < 16 GeV/c and p(T) < 12 GeV/c, respectively, on the centrality of the collision has been measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) in d + Au collisions at root s(NN) = 200 GeV. The measured yields are compared to those in p + p collisions at the same root s(NN) scaled by the number of underlying nucleon-nucleon collisions in d + Au. At all centralities, the yield ratios show no suppression, in contrast to the strong suppression seen for central An + Au collisions at RHIC. Only a weak p(T) and centrality dependence can be observed.


Correlated Production Of P And P¯ Source In Au + Au Collisions At √Snn=200 Gev, Andrew Adare, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, Carla Vale, et al. 2017 University of Colorado, Boulder

Correlated Production Of P And P¯ Source In Au + Au Collisions At √Snn=200 Gev, Andrew Adare, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, Carla Vale, Et Al.

Craig Ogilvie

Correlations between p and p¯ at transverse momenta typical of enhanced baryon production in Au + Au collisions are reported. The PHENIX experiment has measured same and opposite sign baryon pairs in Au + Au collisions at √sNN=200 GeV. Correlated production of p and p¯ with the trigger particle from the range 2.5 < pT < 4.0 GeV/c and the associated particle with 1.8 < pT < 2.5 GeV/c is observed to be nearly independent of the centrality of the collisions. Same sign pairs show no correlation at any centrality. The conditional yield of mesons triggered by baryons (and anti-baryons) and mesons in the same pT range rises with increasing centrality, except for the most central collisions, where baryons show a significantly smaller number of associated mesons. These data are consistent with a picture in which hard scattered partons produce correlated p and p¯ in the pT region of ...


Common Suppression Pattern Of Eta And Pi(0) Mesons At High Transverse Momentum In Au Plus Au Collisions At Root Snn=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, et al. 2017 Brookhaven National Laboratory

Common Suppression Pattern Of Eta And Pi(0) Mesons At High Transverse Momentum In Au Plus Au Collisions At Root Snn=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al.

Craig Ogilvie

Inclusive transverse momentum spectra of eta mesons have been measured within p(T)=2-10 GeV/c at midrapidity by the PHENIX experiment in Au+Au collisions at root s(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au+Au, d+Au, and p+p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi(0). The ratio of eta to pi(0) spectra at high p(T) amounts to 0.40 < R-eta/pi(0)< 0 ...


Cross Section And Parity-Violating Spin Asymmetries Of W-+/- Boson Production In Polarized P Plus P Collisions At Root S=500 Gev, Andrew Adare, Alan Dion, John C. Hill, Todd Kempel, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Marzia Rosati, C. L. Silva, Feng Wei, et al. 2017 University of Colorado, Boulder

Cross Section And Parity-Violating Spin Asymmetries Of W-+/- Boson Production In Polarized P Plus P Collisions At Root S=500 Gev, Andrew Adare, Alan Dion, John C. Hill, Todd Kempel, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Marzia Rosati, C. L. Silva, Feng Wei, Et Al.

Craig Ogilvie

Large parity-violating longitudinal single-spin asymmetries A(L)(e+) = 0.86(-0.14)(+0.30) and Ae(L)(e-) = 0.88(-0.71)(+0.12) are observed for inclusive high transverse momentum electrons and positrons in polarized p + p collisions at a center-of-mass energy of root s = 500 GeV with the PHENIX detector at RHIC. These e(+/-) come mainly from the decay of W-+/- and Z(0) bosons, and their asymmetries directly demonstrate parity violation in the couplings of the W-+/- to the light quarks. The observed electron and positron yields were used to estimate W-+/- boson production cross sections for ...


Cross Section And Double Helicity Asymmetry For Eta Mesons And Their Comparison To Pi(0) Production In P Plus P Collisions At Root S=200 Gev, Andrew Adare, Nathan C. Grau, John C. Hill, Todd Kempel, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Marzia Rosati, Alexey Yu. Semenov, S. Skutnik, Carla Vale, Feng Wei, et al. 2017 University of Colorado, Boulder

Cross Section And Double Helicity Asymmetry For Eta Mesons And Their Comparison To Pi(0) Production In P Plus P Collisions At Root S=200 Gev, Andrew Adare, Nathan C. Grau, John C. Hill, Todd Kempel, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Marzia Rosati, Alexey Yu. Semenov, S. Skutnik, Carla Vale, Feng Wei, Et Al.

Craig Ogilvie

Measurements of double-helicity asymmetries in inclusive hadron production in polarized p + p collisions are sensitive to helicity-dependent parton distribution functions, in particular, to the gluon helicity distribution, Delta g. This study focuses on the extraction of the double-helicity asymmetry in eta production ((p) over right arrow + (p) over right arrow -> eta + X), the eta cross section, and the eta/pi(0) cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to access the helicity-dependent parton distribution functions.


Charged Kaon Interferometric Probes Of Space-Time Evolution In Au Plus Au Collisions At S(Nn)=200 Gev, S. Afanasiev, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, S. Skutnik, Carla Vale, et al. 2017 Joint Institute for Nuclear Research

Charged Kaon Interferometric Probes Of Space-Time Evolution In Au Plus Au Collisions At S(Nn)=200 Gev, S. Afanasiev, Sergey Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, S. Skutnik, Carla Vale, Et Al.

Craig Ogilvie

Bose-Einstein correlations of charged kaons are used to probe Au+Au collisions at s(NN)=200 GeV and are compared to charged pion probes, which have a larger hadronic scattering cross section. Three-dimensional Gaussian source radii are extracted, along with a one-dimensional kaon emission source function. The centrality dependences of the three Gaussian radii are well described by a single linear function of N-part(1/3) with a zero intercept. Imaging analysis shows a deviation from a Gaussian tail at r greater than or similar to 10 fm, although the bulk emission at lower radius is well described by a ...


Digital Commons powered by bepress