Elementary Particles and Fields and String Theory Commons^™

Simulation Of Inverse Compton Scattering And Its Implications On The Scattered Linewidth, N. Ranjan, B. Terzić, G. A. Krafft, V. Petrillo, I. Drebot, L. Serafini

Physics Faculty Publications

Rising interest in inverse Compton sources has increased the need for efficient models that properly quantify the behavior of scattered radiation given a set of interaction parameters. The current state-of-the-art simulations rely on Monte Carlo-based methods, which, while properly expressing scattering behavior in high-probability regions of the produced spectra, may not correctly simulate such behavior in low-probability regions (e.g. tails of spectra). Moreover, sampling may take an inordinate amount of time for the desired accuracy to be achieved. In this paper, we present an analytic derivation of the expression describing the scattered radiation linewidth and propose a model to describe …

Resonances From Lattice Qcd, Raúl A. Briceño

Physics Faculty Publications

The spectrum of hadron is mainly composed as shortly-lived states (resonance) that decay onto two or more hadrons. These resonances play an important role in a variety of phenomenologically significant processes. In this talk, I give an overview on the present status of a rigorous program for studying of resonances and their properties using lattice QCD. I explain the formalism needed for extracting resonant amplitudes from the finite-volume spectra. From these one can extract the masses and widths of resonances. I present some recent examples that illustrate the power of these ideas. I then explain similar formalism that allows for …

Numerical Study Of The Relativistic Three-Body Quantization Condition In The Isotropic Approximation, Raúl A. Briceño, Maxwell T. Hansen, Stephen R. Sharpe

Physics Faculty Publications

We present numerical results showing how our recently proposed relativistic three-particle quantization condition can be used in practice. Using the isotropic (generalized s-wave) approximation, and keeping only the leading terms in the effective range expansion, we show how the quantization condition can be solved numerically in a straightforward manner. In addition, we show how the integral equations that relate the intermediate three-particle infinite-volume scattering quantity, K_df,3, to the physical scattering amplitude can be solved at and below threshold. We test our methods by reproducing known analytic results for the 1/L expansion of the threshold state, the volume …

High Field Q Slope And The Effect Of Low-Temperature Baking At 3 Ghz, G. Ciovati, G. Eremeev, F. Hannon

Physics Faculty Publications

A strong degradation of the unloaded quality factor with field, called high field Q slope, is commonly observed above B_p ≅ 100 mT in elliptical superconducting niobium cavities at 1.3 and 1.5 GHz. In the present experiments several 3 GHz niobium cavities were measured up to and above B_p ≅ 100 mT. The measurements show that a high field Q slope phenomenon limits the field reach at this frequency, that the high field Q slope onset field depends weakly on the frequency, and that the high field Q slope can be removed by the typical empirical solution of …

Isoscalar Ππ; Kk; Ηη Scattering And The Σ; F0; F2 Mesons From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson

Physics Faculty Publications

We present the first lattice QCD study of coupled isoscalar ππ;K ¯K; ηη S- and D-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the light quark mass corresponding to m_π ∼ 391 MeV. In the J^P = 0⁺ sector we find analogues of the experimental σ and f₀ (980) states, where the σ appears as a stable bound-state below ππ threshold, and, similar to what is seen in experiment, the f₀ (980) manifests itself as a dip in the ππ cross section in the vicinity of the …

Quark Pseudodistributions At Short Distances, A. V. Radyushkin

Physics Faculty Publications

We perform a one-loop study of the small-z2 3 behavior of the Ioffe-time distribution (ITD) M(ν, z2 3), the basic function that may be converted into parton pseudo- and quasi-distributions. We calculate the corrections on the operator level, so that our results may be also used for pseudo-distribution amplitudes and generalized parton pseudodistributions. We separate two sources of the z2 3-dependence at small z2 the reduced ITD given by the ratio M(ν, z2 due to ln z2 3)/M(0, z2 3. One is related to the ultraviolet (UV) singularities generated by the gauge link. Our …

Scattering Processes And Resonances From Lattice Qcd, Raúl A. Briceño, Jozef J. Dudek, Ross D. Young

Physics Faculty Publications

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter …

Measurement Of The Q² Dependence Of The Deuteron Spin Structure Function G1 And Its Moments At Low Q² With Clas, Clas Collaboration, K. P. Adhikari, L. El Fassi, S E. Kuhn, M. J. Amaryan, S. Bültmann, G. Charles, Gail Dodge, N. Guler, C. E. Hyde, A. Klein, D. Payette, J. Poudel, Y. Prok, L. B. Weinstein, J. Zhang, Z. W. Zhao

Physics Faculty Publications

We measured the g₁ spin structure function of the deuteron at low Q², where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W ≈ 1.9  GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γ^d₁ and the spin polarizability γ^d₀ are precisely determined down to a minimum Q² of 0.02  GeV² for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first in a …

Semi-Inclusive Πº Target And Beam-Target Asymmetries From 6 Gev Electron Scattering With Clas, S. Koirala, S E. Kuhn, D. Adikaram, M. J. Amaryan, S. Bültmann, G. Charles, Gail Dodge, N. Guler, M. Khachatryan, A. Klein, Y. Prok, L. B. Weinstein, Z. W. Zhao

Physics Faculty Publications

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic ¹⁴NH₃ target, and extracted double and single target spin asymmetries for ep → e′π⁰X in multidimensional bins in four-momentum transfer (1.0 < Q² < 3.2 GeV²), Bjorken-x (0.12 < x < 0.48), hadron energy fraction (0.4 < z < 0.7), transverse pion momentum (0 < P_T < 1.0 GeV), and azimuthal angle ϕ_h between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and P_T, which provide access to transverse-momentum …

Exclusive Photoproduction Of Πº Up To Large Values Of Mandelstam Variables S, T, And U With Clas, Clas Collaboration, M. C. Kunkel, M. J. Amaryan, S. Bültmann, G. Charles, C. E. Hyde, A. Klein, S E. Kuhn, J. Poudel, Y. Prok, L. B. Weinstein, Z. W. Zhao

Physics Faculty Publications

Exclusive photoproduction cross sections have been measured for the process γp→pπ⁰[e⁺e⁻(γ)] with the Dalitz decay final state using tagged photon energies in the range of E_γ= 1.275–5.425 GeV. The complete angular distribution of the final state π⁰ , for the entire photon energy range up to large values of t and u, has been measured for the first time. The data obtained show that the cross section dσ/dt , at mid to large angles, decreases with energy as s^{−6.89±0.26} . This is in agreement with the perturbative QCD quark …

First Measurement Of The Ar (E,E')X Cross Section At Jefferson Laboratory, H. Dai, M. Murphy, V. Pandey, D. Abrams, D. Nguyen, B. Aljawrneh, F. Hauenstein, D. W. Higinbotham, Charles Hyde, The Jefferson Lab Hall A Collaboration

Physics Faculty Publications

The success of the ambitious programs of both long- and short-baseline neutrino-oscillation experiments employing liquid-argon time-projection chambers will greatly rely on the precision with which the weak response of the argon nucleus can be estimated. In the E12-14-012 experiment at Jefferson Lab Hall A, we studied the properties of the argon nucleus by scattering a high-quality electron beam off a high-pressure gaseous argon target. Here, we present the measured ⁴⁰Ar(e,e') double differential cross section at incident electron energy E=2.222 GeV and scattering angle Θ = 15.54°. The data cover a broad range of energy transfers, where quasielastic scattering and …

Exclusive Studiess Of Short Range Correlations In Nuclei Using Clas12 Proposal To Jefferson Lab Pac 46, A. Ashkenazy, R. Cruz Torres, S. Gilad, O. Hen, G. Laskaris, A. Papadopoulou, M. Patsyuk, A. Schmidt, B. Schmookler, E. P. Segarra, F. Hauenstein, M. Hattawy, C. Hyde, M. Khachatryan, S. Kuhn, L. B. Weinstein, E. O. Cohen, M. Duer, E. Piasetzky, D. Higinbotham, S. Stepanyan, H. Szumila-Vance, S. A. Wood, Christopher Marshall, K. Mahn, J. Morrison, L. Pickering, A. Beck, I. Korover, S. Mey-Tal Beck, A. El Alaoui, H. Hakobian, T. Mineeva, J. Miller, W. Brooks, M. Betancourt, T. Katori, I. Balossino, D. Watts, L. Zana, D. Ireland, D. Sokhan, N. Kalantarians, S. Li

Physics Faculty Publications

Short-ranged correlated (SRC) nucleon-nucleon (NN) pairs account for about 20% of all nucleons in medium to heavy nuclei and about 75% of the nuclear kinetic energy. In addition, there is strong evidence linking these pairs to nucleon structure modification in nuclei (the EMC effect). A Significant amount of our knowledge of SRC pairs comes from hard two nucleon knockout measurements, conducted using electron (i.e. (e e'pp) and (e,e'pn)) and proton probes (i.e. (p, 2pn)). These studies show that almost all high-momentum nucleons belong to SRC pairs, that these pairs are predominantly pn pairs …

A Glimpse Of Gluons Through Deeply Virtual Compton Scattering On The Proton, M. Defurne, A. Marti Jimenez-Arguello, Z. Ahmed, H. Albataineh, K. Allada, K. A. Aniol, V. Bellini, M. Benali, W. Boeglin, P. Bertin, M. Canan, C. E. Hyde, M. N. H. Rashad

Physics Faculty Publications

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting …

Lattice Qcd Exploration Of Parton Pseudo-Distribution Functions, Kostas Orginos, Anatoly Radyushkin, Joseph Karpie, Savvas Zafeiropoulos

Physics Faculty Publications

We demonstrate a new method of extracting parton distributions from lattice calculations. The starting idea is to treat the generic equal-time matrix element M(Pz(3), z(3)(2)) as a function of the Ioffe time nu = Pz(3) and the distance z(3). The next step is to divide M(Pz(3), z(3)(2)) by the rest-frame density M(0, z(3)(2)). Our lattice calculation shows a linear exponential z(3)-dependence in the rest-frame function, expected from the Z(z(3)(2)) factor generated by the gauge link. Still, we observe that the ratio M (Pz(3), z(3)(2))/M(Pz(3), z(3)(2)) has a Gaussian-type behavior with respect to z(3) for 6 values of P used in …

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.

Rosenbluth Separation Of The Π0 Electroproduction Cross Section Off The Neutron, M. Mazouz, Z. Ahmed, H. Albataineh, K. Allada, K. A. Aniol, V. Bellini, M. Benali, W. Boeglin, P. Bertin, M. Canan, C. E. Hyde, S. Koirala, M. N. H. Rashad

Physics Faculty Publications

We report the first longitudinal-transverse separation of the deeply virtual exclusive π⁰ electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_L/dt, dσ_T/dt, dσ_LT/dt, and dσ_TT/dt are extracted as a function of the momentum transfer to the recoil system at Q² = 1.75 GeV² and x_B = 0.36. The ed -> edπ⁰ cross sections are found compatible with the small values expected from theoretical models. The en -> enπ⁰ cross sections show a dominance from the response to transversely polarized …

What Are The Low-Q And Large-X Boundaries Of Collinear Qcd Factorization Theorems?, E. Moffat, W. Melnitchouk, T. C. Rogers, N. Sato

Physics Faculty Publications

Familiar factorized descriptions of classic QCD processes such as deeply inelastic scattering (DIS) apply in the limit of very large hard scales, much larger than nonperturbative mass scales and other nonperturbative physical properties like intrinsic transverse momentum. Since many interesting DIS studies occur at kinematic regions where the hard scale, Q ∼ 1-2 GeV, is not very much greater than the hadron masses involved, and the Bjorken scaling variable x_bj is large, x_bj ≳ 0.5, it is important to examine the boundaries of the most basic factorization assumptions and assess whether improved starting points are needed. Using an …

Modeling Local Crabbing Dynamics In The Jleic Ion Collider Ring, Salvador Sosa Guitron, Vasiliy Morozov, Jean Delayen

Physics Faculty Publications

The Jefferson Lab Electron-Ion Collider (JLEIC) design considers a 50 mrad crossing angle at the Interaction Point. Without appropriate compensation, this could geometrically reduce the luminosity by an order of magnitude. A local crabbing scheme is implemented to avoid the luminosity loss: crab cavities are placed at both sides of the interaction region to restore a head-on collision scenario. In this contribution, we report on the implementation of a local crabbing scheme in the JLEIC ion ring. The effects of this correction scheme on the stability of proton bunches are analyzed using the particle tracking software elegant.

Wakefield Analysis Of Superconducting Rf-Dipole Cavities, Subashini De Silva, Jean Delayen

Physics Faculty Publications

RF-dipole crabbing cavities are being considered for a variety of crabbing applications. Some of the applications are the crabbing cavity systems for LHC High Luminosity Upgrade and the proposed Electron-Ion Collider for Jefferson Lab. The design requirements in the current applications require the cavities to incorporate complex damping schemes to suppress the higher order modes that may be excited by the high intensity proton or electron beams traversing through the cavities. The number of cavities required to achieve the desired high transverse voltage, and the complexity in the cavity geometries also contributes to the wakefields generated by beams. This paper …

Pion Distribution Amplitude And Quasidistributions, A. V. Radyushkin

Physics Faculty Publications

We extend our analysis of quasidistributions onto the pion distribution amplitude. Using the formalism of parton virtuality distribution amplitudes, we establish a connection between the pion transverse momentum dependent distribution amplitude Ψ(x, k²_⊥) and the pion quasidistribution amplitude (QDA) Q_π(y, p₃). We build models for the QDAs from the virtuality-distribution-amplitude-based models for soft transverse momentum dependent distribution amplitudes, and analyze the p₃ dependence of the resulting QDAs. As there are many models claimed to describe the primordial shape of the pion distribution amplitude, we present the p₃-evolution …

Harmonically Resonant Cavity As A Bunch Length Monitor, B. Roberts, M. Pablo, E. Forman, J. Grames, F. Hannon, R.Kazimi W. Moore, M. M. Ali

Physics Faculty Publications

A compact, harmonically-resonant cavity with a fundamental resonant frequency of 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). The cavity’s antenna was attached directly to a sampling oscilloscope that detected the electron bunches as they passed through the cavity bore with a sensitivity of ~ mV/ μA. The oscilloscope wave-forms are a superposition of the harmonic modes excited by …

Isoscalar 𝜋𝜋 Scattering And The Σ Meson Resonance From Qcd, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson

Physics Faculty Publications

We present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the KK¯ threshold. Calculations are performed at two values of the u, d quark mass corresponding to m_π=236,391  MeV, and the resulting amplitudes …

Relating The Finite-Volume Spectrum And The Two And Three-Particle S Matrix For Relativistic Systems Of Identical Scalar Particles, Raúl Briceño, Maxwell T. Hansen, Stephen R. Sharpe

Physics Faculty Publications

Working in relativistic quantum field theory, we derive the quantization condition satisfied by coupled two- and three-particle systems of identical scalar particles confined to a cubic spatial volume with periodicity L. This gives the relation between the finite-volume spectrum and the infinite-volume 2 → 2, 2 → 3, and 3 → 3 scattering amplitudes for such theories. The result holds for relativistic systems composed of scalar particles with nonzero mass m, whose center of mass energy lies below the four-particle threshold, and for which the two-particle K matrix has no singularities below the three-particle threshold. The quantization condition is exact …

Role Of The Euclidean Signature In Lattice Calculations Of Quasidistributions And Other Nonlocal Matrix Elements, Raúl A. Briceño, Maxwell T. Hansen, Christopher J. Monahan

Physics Faculty Publications

Lattice quantum chromodynamics (QCD) provides the only known systematic, nonperturbative method for first-principles calculations of nucleon structure. However, for quantities such as light-front parton distribution functions (PDFs) and generalized parton distributions (GPDs), the restriction to Euclidean time prevents direct calculation of the desired observable. Recently, progress has been made in relating these quantities to matrix elements of spatially nonlocal, zero-time operators, referred to as quasidistributions. Still, even for these time-independent matrix elements, potential subtleties have been identified in the role of the Euclidean signature. In this work, we investigate the analytic behavior of spatially nonlocal correlation functions and demonstrate that …

Differential Cross Sections And Polarization Observables From Clas K* Photoproduction And The Search For New N* States, A.V. Anisovich, K. Hicks, E. Klempt, V. A. Nikonov, A. Sarantsev, W. Tang, D. Adhikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, R. A. Badui, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, W. J. Briscoe, V. D. Burkert, D. S. Carman, I Zonta

Physics Faculty Publications

The reaction 𝛄p → K^⁎⁺Λ was measured using the CLAS detector for photon energies between the threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. For the first time, spin-density matrix elements have been extracted for this reaction. Differential cross sections, spin density matrix elements, and the Λ recoil polarization are compared with theoretical predictions using the BnGa partial wave analysis. The main result is the evidence for significant contributions from N(1895)1/2^- and N(2100)1/2⁺ to the reaction. Branching ratios for decays into K^⁎Λ for these resonances and further resonances are reported.

Measurement Of Deep Exclusive Π- Production Using A Transversely Polarized ³He Target And Solid Spectrometer, J. Arrington, K. Hafidi, M. Hattawy, P. Reimer, S. Riordan, Z. Ye, Z. Ahmed, G. R. Ambrose, S. Basnet, R. S. Evans, G. M. Huber, W. Li, D. Paudyal, Z. Papandreou, H. Gao, X. Li, T. Liu, C. Peng, W. Xiong, X. F. Yan, Z. Zhao, A. Camsonne, J-P. Chen, S. Covrig-Dusa, D. Gaskell, T. Brecelj, M. Milhovilovič, S. Širca, S. Štajner, K. Aniol, M. Boer, D. Dutta, L. Ye, C. E. Hyde, F. R. Wesselmann, P. Markowitz, V. Sulkosky, E. Voutier

Physics Faculty Publications

We propose to measure the transverse nucleon, single-spin asymmetries AUT (Φ, Φs) in the exclusive n→(e, e'π-)p reaction, during the transversely polarized ³He target SIDIS experiment (i.e. E12-10-006 [1]) with SoLID [2]. In principle, as many as six azimuthal modulations of the form Asin(μΦ+λΦS)/UT contribute (where μ and λ are integers) [3], but four of these modulations are small and the physics interest is concentrated in the largest two.

Our primarily goal is the measurment of A sin (Φ-Φs)/UT. This polarization observable has been noted as being sensitive to the spin-flip generalized parton distribution (GPD) E, and factorization studies have …

Nonperturbative Evolution Of Parton Quasi-Distributions, A. V. Radyushkin

Physics Faculty Publications

Using the formalism of parton virtuality distribution functions (VDFs) we establish a connection between the transverse momentum dependent distributions (TMDs) F(x,k²_⊥) and quasi-distributions (PQDs) Q(y,p₃) introduced recently by X. Ji for lattice QCD extraction of parton distributions f(x). We build models for PQDs from the VDF-based models for soft TMDs, and analyze the p₃ dependence of the resulting PQDs. We observe a strong nonperturbative evolution of PQDs for small and moderately large values of p₃ reflecting the transverse momentum dependence of TMDs. Thus, the study of PQDs on the lattice …

The Heavy Photon Search Beamline And Its Performance, N. Baltzell, H. Egiyan, M. Ehrhart, C. Field, A. Freyberger, F.-X. Girod, M. Holtrop, J. Jaros, G. Kalicy, T. Maruyama, H. Vance

Physics Faculty Publications

The Heavy Photon Search (HPS) is an experiment to search for a hidden sector photon, aka a heavy photon or dark photon, in fixed target electroproduction at the Thomas Jefferson National Accelerator Facility (JLab). The HPS experiment searches for the e⁺e^- decay of the heavy photon with bump hunt and detached vertex strategies using a compact, large acceptance forward spectrometer, consisting of a silicon microstrip detector (SVT) for tracking and vertexing, and a PbWO₄ electromagnetic calorimeter for energy measurement and fast triggering. To achieve large acceptance and good vertexing resolution, the first layer of silicon detectors …

Connecting Different Tmd Factorization Formalisms In Qcd, John Collins, Ted C. Rogers

Physics Faculty Publications

In the original Collins-Soper-Sterman (CSS) presentation of the results of transverse-momentum-dependent (TMD) factorization for the Drell-Yan process, results for perturbative coefficients can be obtained from calculations for collinear factorization. Here we show how to use these results, plus known results for the quark form factor, to obtain coefficients for TMD factorization in more recent formulations, e.g., that due to Collins, and apply them to known results at order α²s and α³s. We also show that the "nonperturbative" functions as obtained from fits to data are equal in the two schemes. We compile the higher-order perturbative …

Differential Cross Section Measurements For Γn→Π-P Above The First Nucleon Resonance Region, P. T. Mattione, D. S. Carman, I. I. Strakovsky, R. L. Workman, A. E. Kudryavtsev, A. Svarc, V. E. Tarasov, K. P. Adhikari, S. Adhikari, D. Adikaram, G. Charles, M. Khachatryan, A. Klein, Y. Prok, Z. W. Zhao

Physics Faculty Publications

The quasifree γd→π^-p(p) differential cross section has been measured with CLAS at photon beam energies E_γ from 0.445 to 2.510 GeV (corresponding to W from 1.311 to 2.366 GeV) for pion center-of-mass angles cosθπc.m. from -0.72 to 0.92. A correction for final state interactions has been applied to these data to extract the γn→π^-p differential cross sections. These cross sections are quoted in 8428 (E_γ,cosθπc.m.) bins, a factor of nearly 3 increase in the world statistics for this channel in this kinematic range. These new data …