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Physics Faculty Publications

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Articles 511 - 540 of 2178

Full-Text Articles in Physical Sciences and Mathematics

Taller In The Saddle: Constraining Cmb Physics Using Saddle Points, Jow L. Dylan, Dagoberto Contreras, Douglas Scott, Emory F. Bunn Mar 2019

Taller In The Saddle: Constraining Cmb Physics Using Saddle Points, Jow L. Dylan, Dagoberto Contreras, Douglas Scott, Emory F. Bunn

Physics Faculty Publications

The statistics of extremal points in the cosmic microwave background (CMB) temperature (hot and cold spots) have been well explored in the literature, and have been used to constrain models of the early Universe. Here, we extend the study of critical points in the CMB to the set that remains after removing extrema, namely the saddle points. We perform stacks of temperature and polarization about temperature saddle points in simulations of the CMB, as well as in data from the Plancksatellite. We then compute the theoretical profile of saddle-point stacks, given the underlying power spectra of the CMB. As an …

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Studying The Interface Between Croconic Acid Thin Films And Substrates Using A Slow Positron Beam, Dean Peterson, Jiandang Liu, Jonas Etzweiler, Gabriel Sontoyo, Sara J. Callori, Kimberley R. Cousins, Timothy Usher, Renwu Zhang Jan 2019

Studying The Interface Between Croconic Acid Thin Films And Substrates Using A Slow Positron Beam, Dean Peterson, Jiandang Liu, Jonas Etzweiler, Gabriel Sontoyo, Sara J. Callori, Kimberley R. Cousins, Timothy Usher, Renwu Zhang

Physics Faculty Publications

Croconic acid (CA) is the first organic ferroelectric with a spontaneous polarity in bulk samples comparable to its inorganic counterparts. As a natural extension of study, ultrathin CA films (∼nm scale) were investigated to reveal ferroelectric effects in films on different substrates for their fundamental and industrial significance. However, the void defect at the interface between the film and substrate is presumed to interfere with surface effects. In this work, a non-invasive technique, a slow positron beam, coupled with Doppler broadening energy spectroscopy (DBES), is applied to study the void defects within the interfacial layer between CA films and Si …

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The Second Arm Training And Science Application Event: Training The Next Generation Of Atmospheric Scientists, Virendra P. Ghate, Pavlos Kollias, Susanne Crewell, Ann M. Fridlind, Thijs Heus, Ulrich Löehnert, Maximilian Maahn, Greg M. Mcfarquhar, Dmitri Moisseev, Mariko Oue, Manfred Wendisch, Christopher Williams Jan 2019

The Second Arm Training And Science Application Event: Training The Next Generation Of Atmospheric Scientists, Virendra P. Ghate, Pavlos Kollias, Susanne Crewell, Ann M. Fridlind, Thijs Heus, Ulrich Löehnert, Maximilian Maahn, Greg M. Mcfarquhar, Dmitri Moisseev, Mariko Oue, Manfred Wendisch, Christopher Williams

Physics Faculty Publications

No abstract provided.

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Methods For Registering And Calibrating In Vivo Terahertz Images Of Cutaneous Burn Wounds, Priyamvada Tewari, James Garritano, Neha Bajwa, Shijun Sung, Haochong Huang, Dayong Wang, Warren Grundfest, Daniel B. Ennis, Dan Ruan, Elliott Brown, Erik Dutson, Michael C. Fishbein, Zachary Taylor Jan 2019

Methods For Registering And Calibrating In Vivo Terahertz Images Of Cutaneous Burn Wounds, Priyamvada Tewari, James Garritano, Neha Bajwa, Shijun Sung, Haochong Huang, Dayong Wang, Warren Grundfest, Daniel B. Ennis, Dan Ruan, Elliott Brown, Erik Dutson, Michael C. Fishbein, Zachary Taylor

Physics Faculty Publications

A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% …

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Multi-Band Optical And Near-Infrared Properties Of Faint Submillimeter Galaxies With Serendipitous Alma Detections, Pallavi Patil, Kristina Nyland, Mark Lacy, Duncan Farrah, José Afonso, Wayne A. Barkhouse, Jason Surace Jan 2019

Multi-Band Optical And Near-Infrared Properties Of Faint Submillimeter Galaxies With Serendipitous Alma Detections, Pallavi Patil, Kristina Nyland, Mark Lacy, Duncan Farrah, José Afonso, Wayne A. Barkhouse, Jason Surace

Physics Faculty Publications

We present a catalog of 26 faint submillimeter galaxies (SMGs) in the XMM Large Scale Structure (XMM-LSS) field identified by cross-matching serendipitously detected sources in archival pre–Atacama Large Millimeter Array (ALMA) band 6 and 7 data with multiband near-infrared (NIR) and optical data from the Spitzer Extragalactic Representative Volume Survey, the VISTA Deep Extragalactic Survey, the Canada–France–Hawaii Telescope Legacy Large Survey, and the Hyper Suprime-Cam Subaru Strategic Program. Of the 26 SMGs in our sample, 15 are identified here for the first time. The majority of the sources in our sample (16/26) have faint submillimeter fluxes (0.1 mJy < S 1mm …

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Question 1: Losing Weight; Question 2: Artificial Moon, Larry Weinstein Jan 2019

Question 1: Losing Weight; Question 2: Artificial Moon, Larry Weinstein

Physics Faculty Publications

The article presents questions related to Fermi which include mass lost by Sun over its lifetime; and size of artificial satellite needed to provide as much illumination as a full moon.

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Measurement Of Double-Polarization Asymmetries In The Quasi-Elastic He→ 3 (E→, E′ P) Process, The Jefferson Lab Hall A Collaboration, M. Mihovilović, G. Jin, E. Long, Y.-W. Zhang, K. Allada, B. Anderson, M. Canan, S. Golge, R. Schiavilla Jan 2019

Measurement Of Double-Polarization Asymmetries In The Quasi-Elastic He→ 3 (E→, E′ P) Process, The Jefferson Lab Hall A Collaboration, M. Mihovilović, G. Jin, E. Long, Y.-W. Zhang, K. Allada, B. Anderson, M. Canan, S. Golge, R. Schiavilla

Physics Faculty Publications

We report on a precise measurement of double-polarization asymmetries in electron-induced breakup of 3He proceeding to pd and ppn final states, performed in quasi-elastic kinematics at Q2 = 0.25 (GeV/c)2 for missing momenta up to 250 MeV/c. These observables represent highly sensitive tools to investigate the electromagnetic and spin structure of 3He and the relative importance of two- and three-body effects involved in the breakup reaction dynamics. The measured asymmetries cannot be satisfactorily reproduced by state-of-the-art calculations of 3He unless their three-body segment is adjusted, indicating that the spin-dependent part of …

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Structure Of Parton Quasi-Distributions And Their Moments, A. V. Radyushkin Jan 2019

Structure Of Parton Quasi-Distributions And Their Moments, A. V. Radyushkin

Physics Faculty Publications

We discuss the structure of the parton quasi-distributions (quasi-PDFs) Q (y, P-3) outside the "canonical" -1 <= y <= 1 support region of the usual parton distribution functions (PDFs). Writing the y(n) moments of Q (y, P-3) in terms of the combined x(n-2l)k(perpendicular to)(2l)-moments of the transverse momentum distribution (TMD). F(x,k(perpendicular to)(2)), we establish a connection between the large-vertical bar y vertical bar behavior of Q (y, P-3) and large-k(perpendicular to)(2) behavior of F(x,k(perpendicular to)(2)). In particular, we show that the 1/k(perpendicular to)(2) hard tail of TMDs in QCD results in a slowly decreasing similar to 1/vertical bar y vertical bar behavior of quasi-PDFs for large vertical bar y vertical bar that produces infinite y(n) moments of Q(y, P-3). We also relate the - 1/vertical bar y vertical bar terms with the lnz(3)(2)-singularities of the Ioffe-time pseudo-distributions m(v, z(3)(2)). Converting the operator product expansion for m(v,z(3)(2)) into a matching relation between the quasi-PDF Q(y, P-3) and the light-cone PDF f (x, mu(2)), we demonstrate that there is no contradiction between the infinite values of the y(n) moments of Q (y, P-3) and finite values of the x(n) moments of f (x, mu(2))

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First Results On Nucleon Resonance Photocouplings From The Γp → Π+Π−P Reaction, E. Golovatch, V. D. Burkert, D. S. Carman, R. W. Gothe, K. Hicks, M. J. Amaryan, M. Khachatryan, A. Klein, Y. Prok, Clas Collaboration Jan 2019

First Results On Nucleon Resonance Photocouplings From The Γp → Π+Π−P Reaction, E. Golovatch, V. D. Burkert, D. S. Carman, R. W. Gothe, K. Hicks, M. J. Amaryan, M. Khachatryan, A. Klein, Y. Prok, Clas Collaboration

Physics Faculty Publications

We report the first experimental measurements of the nine 1-fold differential cross sections for the γ p → π+π−p reaction, obtained with the CLAS detector at Jefferson Laboratory. The measurements cover the invariant mass range of the final state hadrons from 1.6 GeV < W < 2.0 GeV. For the first time the photocouplings of all prominent nucleon resonances in this mass range have been extracted from this exclusive channel. Photoproduction of two charged pions is of particular importance for the evaluation of the photocouplings for the Δ (1620)1/2−, Δ (1700)3/2−, N(1720)3/2+, and Δ (1905)5/2+ resonances, which have dominant decays into the π π N final states rather than the more extensively studied single meson decay channels.

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Question 1: Driving Rain, Question 2: Cooking Off Ammo, Larry Weinstein Jan 2019

Question 1: Driving Rain, Question 2: Cooking Off Ammo, Larry Weinstein

Physics Faculty Publications

The article presents two questions on topics including calculation of highway gas mileage decrease in heavy rain and initial velocity of a bullet in case the propellant in its cartridge exploded outside of a gun.

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Polarization Analysis Of P̄ Produced In Pa Collisions, D. Grzonka, D. Alfs, A. Asaturyan, M. Carmignotto, M. Diermaier, W. Eyrich, B. Glowacz, F. Hauenstein, T. Horn, K. Kilian Jan 2019

Polarization Analysis Of P̄ Produced In Pa Collisions, D. Grzonka, D. Alfs, A. Asaturyan, M. Carmignotto, M. Diermaier, W. Eyrich, B. Glowacz, F. Hauenstein, T. Horn, K. Kilian

Physics Faculty Publications

A quite simple procedure for the generation of a polarized antiproton beam could be worked out if antiprotons are produced with some polarization. In order to investigate this possibility measurements of the polarization of produced antiprotons have been started at a CERN/PS test beam. The polarization will be determined from the asymmetry of the elastic antiproton scattering at a liquid hydrogen target in the CNI region for which the analyzing power is well known. The data are under analysis and an additional measurement is done in 2018. Details on the experiment and the ongoing data analysis will be given.

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Polarized Hyperon Production In Single-Inclusive Electron Positron Annihilation At Next-To-Leading Order, Leonard Gamberg, Zhong-Bo Kang, Daniel Pitonyak, Marc Schlegel, Shinsuke Yoshida Jan 2019

Polarized Hyperon Production In Single-Inclusive Electron Positron Annihilation At Next-To-Leading Order, Leonard Gamberg, Zhong-Bo Kang, Daniel Pitonyak, Marc Schlegel, Shinsuke Yoshida

Physics Faculty Publications

We study the production of polarized A-hyperons in electron-positron annihilation. We are particularly interested in the transverse-spin dependence of the cross section for unpolarized incident electron-positron pairs. At high energies this process may be described in the collinear twist-3 framework, where the hadronization transition of partons into a transversely polarized -hyperon can be written in terms of collinear twist-3 fragmentation matrix elements. We calculate the hard partonic cross sections and interference terms in perturbative QCD to next-to-leading order accuracy. We find that the QCD equation of motion plays a crucial role in our analysis. As a byproduct, assuming the validity …

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Three-Particle Systems With Resonant Subprocesses In A Finite Volume, Raúl A. Briceño, Maxwell T. Hansen, Stephen R. Sharpe Jan 2019

Three-Particle Systems With Resonant Subprocesses In A Finite Volume, Raúl A. Briceño, Maxwell T. Hansen, Stephen R. Sharpe

Physics Faculty Publications

In previous work, we have developed a relativistic, model-independent three-particle quantization condition, but only under the assumption that no poles are present in the two-particle K matrices that appear as scattering subprocesses [M. T. Hansen and S. R. Sharpe, Phys. Rev. D 90, 116003 (2014); M. T. Hansen and S. R. Sharpe, Phys. Rev. D 92, 114509 (2015); R. A. Briceño et al., Phys. Rev. D 95, 074510 (2017).]. Here we lift this restriction, by deriving the quantization condition for identical scalar particles with a G-parity symmetry, in the case that the two-particle K matrix has a pole in the …

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Measurement Of The Beam Spin Asymmetry Of →Ep → E'P'Η In The Deep-Inelastic Regime With Clas, B. Zhao, A. Kim, K. Joo, I . Bedlinskiy, W. Kim, V. Kubarovsky, M. Ungaro, G. Gavalian, A. Klein, S. E. Kuhn, Clas Collaboration Jan 2019

Measurement Of The Beam Spin Asymmetry Of →Ep → E'P'Η In The Deep-Inelastic Regime With Clas, B. Zhao, A. Kim, K. Joo, I . Bedlinskiy, W. Kim, V. Kubarovsky, M. Ungaro, G. Gavalian, A. Klein, S. E. Kuhn, Clas Collaboration

Physics Faculty Publications

The beam spin asymmetry of the exclusive pseudoscalar channel →ep→e′p′η was measured for the first time in the deep-inelastic regime (W > 2 GeV/c2 and Q2 > 1 GeV2 /c2) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of Q2, xB, −t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the sin ϕ moments is …

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Solutions For Fermi Questions, February 2019: Question 1: Driving Rain, Question 2: Cooking Off Ammo, Larry Weinstein Jan 2019

Solutions For Fermi Questions, February 2019: Question 1: Driving Rain, Question 2: Cooking Off Ammo, Larry Weinstein

Physics Faculty Publications

The article presents two questions and answers including a decrease in highway gas mileage in heavy rain and the initial velocity of a bullet in case the propellant in its cartridge exploded outside of a gun.

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Spectroscopy Of Neon For The Advanced Undergraduate Laboratory, H. C. Busch, M. B. Cooper, C. I. Sukenik Jan 2019

Spectroscopy Of Neon For The Advanced Undergraduate Laboratory, H. C. Busch, M. B. Cooper, C. I. Sukenik

Physics Faculty Publications

We describe a spectroscopy experiment, suitable for upper-division laboratory courses, that investigates saturated absorption spectroscopy and polarization spectroscopy in a neon discharge. Both experiments use nearly identical components, allowing students to explore both techniques in a single apparatus. Furthermore, because the wavelength of the laser is in the visible part of the spectrum (640 nm), the experiment is well-suited for students with limited experience in optical alignment. The labs nicely complement a course in atomic or plasma physics, provide students with the opportunity to gain important technical skills in the area of optics and lasers, and can provide an introduction …

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Solutions For Fermi Questions, March 2019: Question 1: I'M Stoked!; Question 2: Geckos, Larry Weinstein Jan 2019

Solutions For Fermi Questions, March 2019: Question 1: I'M Stoked!; Question 2: Geckos, Larry Weinstein

Physics Faculty Publications

The article presents questions and answers concerning the maximum power that a coal-power steam engine can attain and the number of geckos needed to lift a glass window pane and a plate-glass window.

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Question 1: I'M Stoked!; Question 2: Geckos, Larry Weinstein Jan 2019

Question 1: I'M Stoked!; Question 2: Geckos, Larry Weinstein

Physics Faculty Publications

A quiz is presented about the maximum power of steam engines and the number of geckos needed to apply enough force to lift a typical glass window pane.

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Direct Observation Of Proton-Neutron Short-Range Correlation Dominance In Heavy Nuclei, M. Duer, A. Schmidt, J. R. Pybus, E. P. Segarra, A. Hrnjic, L. B. Weinstein, M. Hattawy, F. Hauenstein, S.E. Kuhn, Clas Collaboration Jan 2019

Direct Observation Of Proton-Neutron Short-Range Correlation Dominance In Heavy Nuclei, M. Duer, A. Schmidt, J. R. Pybus, E. P. Segarra, A. Hrnjic, L. B. Weinstein, M. Hattawy, F. Hauenstein, S.E. Kuhn, Clas Collaboration

Physics Faculty Publications

We measured the triple coincidence A(e,e′n p) and A(e,e′ p p) reactions on carbon, aluminum, iron, and lead targets at Q2 >1.5  (GeV/c)2, xB > 1.1 and missing momentum >400  MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for single-charge exchange effects decreased the SRC pairs ratio to ∼3%, which is lower than previous results. Comparisons to theoretical …

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Large Transverse Momentum In Semi-Inclusive Deeply Inelastic Scattering Beyond Lowest Order, B. Wang, J. O. Gonzalez-Hernandez, T. C. Rogers, N. Sato Jan 2019

Large Transverse Momentum In Semi-Inclusive Deeply Inelastic Scattering Beyond Lowest Order, B. Wang, J. O. Gonzalez-Hernandez, T. C. Rogers, N. Sato

Physics Faculty Publications

Motivated by recently observed tension between O(α2s) calculations of very large transverse momentum dependence in both semi-inclusive deep inelastic scattering and Drell-Yan scattering, we repeat the details of the calculation through an O(α2s) transversely differential cross section. The results confirm earlier calculations, and provide further support to the observation that tension exists with current parton distribution and fragmentation functions.

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Question 1: Goosed; Question 2: Buying Groceries, Larry Weinstein Jan 2019

Question 1: Goosed; Question 2: Buying Groceries, Larry Weinstein

Physics Faculty Publications

The article presents two questions related to fermi which include injury of a celebrity colliding with a goose in the Apollo's Chariot roller coaster; and cost to purchase the contents of local large supermarket.

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Instability Of Flux Flow And Production Of Vortex-Antivortex Pairs By Current-Driven Josephson Vortices In Layered Superconductors, Ahmad Sheikhzada, Alex Gurevich Jan 2019

Instability Of Flux Flow And Production Of Vortex-Antivortex Pairs By Current-Driven Josephson Vortices In Layered Superconductors, Ahmad Sheikhzada, Alex Gurevich

Physics Faculty Publications

We report numerical simulations of the nonlinear dynamics of Josephson vortices driven by strong dc currents in layered superconductors. Dynamic equations for interlayer phase differences in a stack of coupled superconducting layers were solved to calculate a drag coefficient η(J) of the vortex as a function of the perpendicular dc current density J. It is shown that Cherenkov radiation produced by a moving vortex causes significant radiation drag increasing η(v) at high vortex velocities v and striking instabilities of driven Josephson vortices moving faster than a terminal vc. The steady-state flux flow breaks down at ν > v …

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Drift Chamber Calibration And Particle Identification In The P-349 Experiment, D. Alfs, A. Asaturyan, M. Carmignotto, M. Diermaier, W. Eyrich, B. Glowacz, D. Grzonka, Florian Hauenstein, T. Horn, K. Kilian, D. Lersch, S. Malbrunot-Ettenauer, A. Mkrtchyan, H. Mkrtchyan, P. Moskal, P. Nadel-Turonski, W. Oelert, J. Ritman, T. Sefzick, V. Tadevosyan, E. Widmann, M. Wolke, S. Zhamkochyan, M. Zieliński, A. Zink, J. Zmeskal Jan 2019

Drift Chamber Calibration And Particle Identification In The P-349 Experiment, D. Alfs, A. Asaturyan, M. Carmignotto, M. Diermaier, W. Eyrich, B. Glowacz, D. Grzonka, Florian Hauenstein, T. Horn, K. Kilian, D. Lersch, S. Malbrunot-Ettenauer, A. Mkrtchyan, H. Mkrtchyan, P. Moskal, P. Nadel-Turonski, W. Oelert, J. Ritman, T. Sefzick, V. Tadevosyan, E. Widmann, M. Wolke, S. Zhamkochyan, M. Zieliński, A. Zink, J. Zmeskal

Physics Faculty Publications

The goal of the P-349 experiment is to test whether 3.5 GeV/c antiprotons produced in high-energy proton-proton collisions are polarized in view of the preparation of a polarized antiproton beam. In this article, we present the details of the ongoing analysis focused on the drift chambers calibration and particle identification with DIRC.

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Exploring The Structure Of The Bound Proton With Deeply Virtual Compton Scattering, M. Hattawy, N. A. Baltzell, R. Dupré, S. Bültmann, B. Torayev, G. Gavalian, F. Hauenstein, S. E. Kuhn, M. Khachatryan, M. Mayer, J. Poudel, Y. Prok, L. B. Weinstein, J. Zhang, Z. W. Zhao, Clas Collaboration Jan 2019

Exploring The Structure Of The Bound Proton With Deeply Virtual Compton Scattering, M. Hattawy, N. A. Baltzell, R. Dupré, S. Bültmann, B. Torayev, G. Gavalian, F. Hauenstein, S. E. Kuhn, M. Khachatryan, M. Mayer, J. Poudel, Y. Prok, L. B. Weinstein, J. Zhang, Z. W. Zhao, Clas Collaboration

Physics Faculty Publications

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this Letter, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering …

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First Measurement Of Near-Threshold J/ᴪ Exclusive Photoproduction Off The Proton, M. Ali, M. Amaryan, E.G. Anassontzis, Q. Zhou, X. Zhou, B. Zihlmann, Gluex Collaboration Jan 2019

First Measurement Of Near-Threshold J/ᴪ Exclusive Photoproduction Off The Proton, M. Ali, M. Amaryan, E.G. Anassontzis, Q. Zhou, X. Zhou, B. Zihlmann, Gluex Collaboration

Physics Faculty Publications

We report on the measurement of the γp -> J/ψp cross section from Eγ = 11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67 ± 0.39 GeV-2 at 10.7 GeV average energy. The LHCb pentaquark candidates P+c can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper …

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Form Factors Of Two-Hadron States From A Covariant Finite-Volume Formalism, Alessandro Baroni, Raúl Briceño, Maxwell T. Hansen, Felipe G. Ortega-Gama Jan 2019

Form Factors Of Two-Hadron States From A Covariant Finite-Volume Formalism, Alessandro Baroni, Raúl Briceño, Maxwell T. Hansen, Felipe G. Ortega-Gama

Physics Faculty Publications

In this work we develop a Lorentz-covariant version of the previously derived formalism for relating finite-volume matrix elements to 2 + J → 2 transition amplitudes. We also give various details relevant for the implementation of this formalism in a realistic numerical lattice QCD calculation. Particular focus is given to the role of single-particle form factors in disentangling finite-volume effects from the triangle diagram that arise when J couples to one of the two hadrons. This also leads to a new finite-volume function, denoted G, the numerical evaluation of which is described in detail. As an example we discuss …

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Conformal Invariance Of Transverse-Momentum Dependent Parton Distributions Rapidity Evolution, Ian Balitsky, Giovanni A. Chirilli Jan 2019

Conformal Invariance Of Transverse-Momentum Dependent Parton Distributions Rapidity Evolution, Ian Balitsky, Giovanni A. Chirilli

Physics Faculty Publications

We discuss conformal properties of TMD operators and present the result of the conformal rapidity evolution of TMD operators in the Sudakov region.

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Field-Dependent Nonlinear Surface Resistance And Its Optimization By Surface Nanostructuring In Superconductors, Takayuki Kubo, Alex Gurevich Jan 2019

Field-Dependent Nonlinear Surface Resistance And Its Optimization By Surface Nanostructuring In Superconductors, Takayuki Kubo, Alex Gurevich

Physics Faculty Publications

We propose a theory of nonlinear surface resistance of a dirty superconductor in a strong radio-frequency (rf) field, taking into account magnetic and nonmagnetic impurities, finite quasiparticle lifetimes, and a thin proximity-coupled normal layer characteristic of the oxide surface of many materials. The Usadel equations were solved to obtain the quasiparticle density of states (DOS) and the low-frequency surface resistance Rs as functions of the rf field amplitude H0. It is shown that the interplay of the broadening of the DOS peaks and a decrease of a quasiparticle gap caused by the rf currents produces a minimum …

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Universality Class Of Explosive Percolation In Barabási-Albert Networks, Habib E. Islam, M. K. Hassan Jan 2019

Universality Class Of Explosive Percolation In Barabási-Albert Networks, Habib E. Islam, M. K. Hassan

Physics Faculty Publications

In this work, we study explosive percolation (EP) in Barabási-Albert (BA) network, in which nodes are born with degree k = m, for both product rule (PR) and sum rule (SR) of the Achlioptas process. For m = 1 we find that the critical point tc = 1 which is the maximum possible value of the relative link density t; Hence we cannot have access to the other phase like percolation in one dimension. However, for m > 1 we find that tc decreases with increasing m and the critical exponents ν, α, β and γ …

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Argon Metastable And Resonant Level Densities In Ar And Ar/Cl² Discharges Used For The Processing Of Bulk Niobium, Jeremy Peshl, Roderick Mcneill, Charles I. Sukenik, Milka Nikolić, Svetozar Popović, Leposava Vŭsković Jan 2019

Argon Metastable And Resonant Level Densities In Ar And Ar/Cl² Discharges Used For The Processing Of Bulk Niobium, Jeremy Peshl, Roderick Mcneill, Charles I. Sukenik, Milka Nikolić, Svetozar Popović, Leposava Vŭsković

Physics Faculty Publications

A comparative analysis of two popular spectroscopy techniques is conducted in a coaxial cylindrical capacitively coupled discharge designed for the plasma processing of superconducting radio frequency (SRF) cavities. The density of the metastable and resonant levels in Ar is measured in both Ar and Ar/Cl2 discharges to properly characterize the unique discharge system and aid in the development of a cavity etching routine. The first method, deemed the “branching fraction method,” utilizes the sensitivity of photon reabsorption of radiative decay to measure the lower state (metastable and resonant) densities by taking ratios of spectral lines with a common upper …

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