Elementary Particles and Fields and String Theory Commons^™

Nucleon And Nuclear Structure Through Dilepton Production, I. V. Anikin, N. Baltzell, M. Boer, R. Boussarie, V. M. Braun, S. J. Brodsky, A. Camsonne, W. C. Chang, L. Colaneri, C. E. Hyde

Physics Faculty Publications

Transverse momentum distributions and generalized parton distributions provide a comprehensive framework for the three-dimensional imaging of the nucleon and the nucleus experimentally using deeply virtual semi-exclusive and exclusive processes. The advent of combined high luminosity facilities and large acceptance detector capabilities enables experimental investigation of the partonic structure of hadrons with time-like virtual probes, in complement to the rich on-going space-like virtual probe program. The merits and benefits of the dilepton production channel for nuclear structure studies are discussed within the context of the International Workshop on Nucleon and Nuclear Structure through Dilepton Production taking place at the European Center …

New Result For The Neutron Β-Asymmetry Parameter A0 From Ucna, M. A.-P. Brown, E. B. Dees, E. Adamek, B. Allgeier, M. Blatnik, T. J. Bowles, L. J. Broussard, R. Carr, S. Clayton, C. Cude-Woods, S. Currie, X. Ding, B. W. Filippone, A. García, P. Geltenbort, S. Hasan, K. P. Hickerson, J. Hoagland, R. Hong, G. E. Hogan, A. T. Holley, T. M. Ito, A. Knecht, C. -Y. Liu, J. Liu, M. Makela, J. W. Martin, D. Melconian, M. P. Mendenhall, S. D. Moore, Subash C. Nepal, N. Nouri, Bradley R. Plaster

Physics and Astronomy Faculty Publications

Background: The neutron β-decay asymmetry parameter A₀ defines the angular correlation between the spin of the neutron and the momentum of the emitted electron. Values for A₀ permit an extraction of the ratio of the weak axial-vector to vector coupling constants, λ ≡ g_A/g_V, which under assumption of the conserved vector current hypothesis (g_V = 1) determines g_A. Precise values for g_A are important as a benchmark for lattice QCD calculations and as a test of the standard model.

Purpose: The UCNA experiment, carried out at the …

Pulse Height Spectra Analysis Of A Neutron Energy Tuning Assembly, Jason R. Stickney

Theses and Dissertations

An energy tuning assembly (ETA) was previously designed and built for the purpose of irradiating samples with a combination of a thermonuclear and a prompt fission neutron spectrum. Initial research was performed to characterize the performance of the ETA at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron using 33 MeV deuteron breakup on tantalum as the neutron source. This research analyzes detector responses collected from three EJ-309 detectors used to characterize the ETA generated neutron field. A signal processing chain was developed to reduce the full waveform data into a pulse height spectrum. The primary goal was to develop a …

Phenomenology Of Neutron-Antineutron Conversion, Susan Gardner, Xinshuai Yan

Physics and Astronomy Faculty Publications

We consider the possibility of neutron-antineutron (n−n¯) conversion, in which the change of a neutron into an antineutron is mediated by an external source, as can occur in a scattering process. We develop the connections between n−n¯ conversion and n−n¯ oscillation, in which a neutron spontaneously transforms into an antineutron, noting that if n−n¯ oscillation occurs in a theory with baryon number minus lepton number (B-L) violation, then n−n¯ conversion can occur also. We show how an experimental limit on n−n¯ …

Universality Of Quantum Information In Chaotic Cfts, Nima Lashkari, Anatoly Dymarsky, Hong Liu

Physics and Astronomy Faculty Publications

We study the Eigenstate Thermalization Hypothesis (ETH) in chaotic conformal field theories (CFTs) of arbitrary dimensions. Assuming local ETH, we compute the reduced density matrix of a ball-shaped subsystem of finite size in the infinite volume limit when the full system is an energy eigenstate. This reduced density matrix is close in trace distance to a density matrix, to which we refer as the ETH density matrix, that is independent of all the details of an eigenstate except its energy and charges under global symmetries. In two dimensions, the ETH density matrix is universal for all theories with the …

Anomalous Electromagnetic Transport In Compact Stars, Efrain J. Ferrer, Vivian De La Incera

Publications and Research

We study the anomalous electromagnetic transport properties of a quark-matter phase that can be realized in the presence of a magnetic field in the low-temperature/moderate-high-density region of the Quantum Chromodynamics (QCD) phase map. In this so-called Magnetic Dual Chiral Density Wave phase, an inhomogeneous condensate is dynamically induced producing a nontrivial topology, a consequence of the asymmetry of the lowest Landau level modes of the quasiparticles in this phase. The nontrivial topology manifests in the electromagnetic effective action via a chiral anomaly term θF^µνF˜_µν, with an axion field θ given by the phase of the Dual …

The 3d Stress-Tensor Bootstrap, Anatoly Dymarsky, Filip Kos, Petr Kravchuk, David Poland, David Simmons-Duffin

Physics and Astronomy Faculty Publications

We study the conformal bootstrap for 4-point functions of stress tensors in parity-preserving 3d CFTs. To set up the bootstrap equations, we analyze the constraints of conformal symmetry, permutation symmetry, and conservation on the stress-tensor 4-point function and identify a non-redundant set of crossing equations. Studying these equations numerically using semidefinite optimization, we compute bounds on the central charge as a function of the independent coefficient in the stress-tensor 3-point function. With no additional assumptions, these bounds numerically reproduce the conformal collider bounds and give a general lower bound on the central charge. We also study the effect of gaps …

Variance Reduction And Cluster Decomposition, Keh-Fei Liu, Jian Liang, Yi-Bo Yang

Physics and Astronomy Faculty Publications

It is a common problem in lattice QCD calculation of the mass of the hadron with an annihilation channel that the signal falls off in time while the noise remains constant. In addition, the disconnected insertion calculation of the three-point function and the calculation of the neutron electric dipole moment with the θ term suffer from a noise problem due to the √V fluctuation. We identify these problems to have the same origin and the √V problem can be overcome by utilizing the cluster decomposition principle. We demonstrate this by considering the calculations of the glueball mass, the …

Time-Resolved Electron (E,2E) Momentum Spectroscopy: Application To Laser-Driven Electron Population Transfer In Atoms, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

Owing to its ability to provide unique information on electron dynamics, time-resolved electron momentum spectroscopy (EMS) is used to study theoretically a laser-driven electronic motion in atoms. Specifically, a chirped laser pulse is used to adiabatically transfer the populations of lithium atoms from the ground state to the first excited state. During this process, impact ionization near the Bethe ridge by time-delayed ultrashort, high-energy electron pulses is used to image the instantaneous momentum density of this electronic population transfer. Simulations with 100 fs and 1 fs pulse durations demonstrate the capability of EMS to image the time-varying momentum density, including …

Azimuthal Transverse Single-Spin Asymmetries Of Inclusive Jets And Charged Pions Within Jets From Polarized-Proton Collisions At √S = 500 Gev, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet + π^± production at midrapidity from transversely polarized proton-proton collisions at √s = 500  GeV. The data were collected in 2011 with the STAR detector sampled from 23  pb⁻¹ integrated luminosity with an average beam polarization of 53%. Asymmetries are reported for jets with transverse momenta 6 < p_T < 55  GeV/c and pseudorapidity |η| < 1. Presented are measurements of the inclusive-jet azimuthal transverse single-spin asymmetry, sensitive to twist-3 initial-state quark-gluon correlators; the Collins asymmetry, sensitive to quark transversity coupled to the polarized Collins fragmentation function; and the first measurement of the “Collins-like” asymmetry, sensitive to linearly polarized gluons. Within the present statistical precision, inclusive-jet and Collins-like asymmetries are small, with the latter allowing the first experimental constraints on gluon linear polarization in a polarized proton. At higher values of jet transverse momenta, we observe the first nonzero Collins asymmetries in polarized-proton collisions, with a statistical significance of greater than 5σ. The results span a range of x similar to results from semi-inclusive deep-inelastic scattering but at much higher Q². The Collins results enable tests of …

Light-Nuclei Spectra From Chiral Dynamics, M. Piarulli, A. Baroni, L. Girlanda, A. Kievsky, A. Lovato, Ewing Lusk, L. E. Marcucci, Steven C. Pieper, R. Schiavilla, M, Viviani, R. B. Wiringa

Physics Faculty Publications

In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. In this Letter, we present Green's function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levels and …

Universality Of Fast Quenches From The Conformal Perturbation Theory, Anatoly Dymarsky, Michael Smolkin

Physics and Astronomy Faculty Publications

We consider global quantum quenches, a protocol when a continuous field theoretic system in the ground state is driven by a homogeneous time-dependent external interaction. When the typical inverse time scale of the interaction is much larger than all relevant scales except for the UV-cutoff the system’s response exhibits universal scaling behavior. We provide both qualitative and quantitative explanations of this universality and argue that physics of the response during and shortly after the quench is governed by the conformal perturbation theory around the UV fixed point. We proceed to calculate the response of one and two-point correlation functions confirming …

Applications Of Effective Field Theories To New Physics, Derek Edward Hazard

Wayne State University Dissertations

We apply an effective field theory approach and argue that lepton flavor violating (LFV) decays M → l1l2 of meson states M with different quantum numbers could be used to put constraints on the Wilson coefficients of effective operators describing LFV interactions at low energy scales. We note that the restricted kinematics of the two-body decay of quarkonium or a heavy quark meson allows us to select operators with particular quantum numbers, significantly reducing the reliance on the single operator dominance assumption that is prevalent in constraining parameters of the effective LFV Lagrangian. We shall also argue that studies of …

Xuv-Assisted High-Order-Harmonic-Generation Spectroscopy, T. S. Sarantseva, M. V. Frolov, N. L. Manakov, A. A. Silaev, N. V. Vvedenskii, Anthony F. Starace

Anthony F. Starace Publications

Using the analytic time-dependent effective range theory, we study two-color high-order harmonic generation (HHG) involving a weak extreme ultraviolet (XUV) pulse and an intense infrared laser field. Our analysis shows that XUV-assisted HHG spectra contain multiple additional plateau structures originating from absorption of one or more XUV photons at the photorecombination step of HHG. We show also that the HHG rate corresponding to the nth plateau can be presented in a factorized form involving the XUV-assisted (multiphoton) photorecombination cross section (PRCS) corresponding to absorption of n XUV photons of energy Ω and emission of a harmonic of energy Ω_{h …}

Higher Cluster Categories And Qft Dualities, Sebastián Franco, Gregg Musiker

Publications and Research

We introduce a unified mathematical framework that elegantly describes minimally supersymmetry gauge theories in even dimensions, ranging from six dimensions to zero dimensions, and their dualities. This approach combines and extends recent developments on graded quivers with potentials, higher Ginzburg algebras, and higher cluster categories (also known as m-cluster categories). Quiver mutations studied in the context of mathematics precisely correspond to the order-(m + 1) dualities of the gauge theories. Our work indicates that these equivalences of quiver gauge theories sit inside an infinite family of such generalized dualities.

Warp Drive Spacetimes, Nicholas A.S. Driver

Theses and Dissertations

The concept of faster than light travel in general relativity is examined, starting with a review of the Alcubierre metric. This spacetime, although incredible in its implications, has certain unavoidable problems which are discussed in detail. It is demonstrated that in order to describe faster than light travel without any ambiguities, a coordinate independent description is much more convenient. An alternative method of describing superluminal travel is then proposed, which has similarities to the Krasnikov tube.

Numerical Simulation For A Rising Bubble Interacting With A Solid Wall: Impact, Bounce, And Thin Film Dynamics, Changjuan Zhang, Jie Li, Li-Shi Luo, Tiezheng Qian

Mathematics & Statistics Faculty Publications

Using an arbitrary Lagrangian-Eulerian method on an adaptive moving unstructured mesh, we carry out numerical simulations for a rising bubble interacting with a solid wall. Driven by the buoyancy force, the axisymmetric bubble rises in a viscous liquid toward a horizontal wall, with impact on and possible bounce from the wall. First, our simulation is quantitatively validated through a detailed comparison between numerical results and experimental data. We then investigate the bubble dynamics which exhibits four different behaviors depending on the competition among the inertial, viscous, gravitational, and capillary forces. A phase diagram for bubble dynamics has been produced using …

Global Constraints On Top Quark Anomalous Couplings, Frédéric Déliot, Ricardo Faria, Miguel C. N. Fiolhais, Pedro Lagarelhos, António Onofre, Christopher M. Pease, Ana Vasconcelos

Publications and Research

The latest results on top quark physics, namely single top quark production cross sections, W-boson helicity and asymmetry measurements are used to probe the Lorentz structure of the Wtb vertex. The increase of sensitivity to new anomalous physics contributions to the top quark sector of the standard model is quantified by combining the relevant results from Tevatron and the Large Hadron Collider. The results show that combining an increasing set of available precision measurements in the search for new physics phenomena beyond the standard model leads to significant sensitivity improvements, especially when compared with the current expectation for the …

Bipartite Field Theories And D-Brane Instantons, Sebastían Franco, Eduardo García-Valdecasas, Angel M. Uranga

Publications and Research

We study D-brane instantons in systems of D3-branes at toric CY 3-fold singularities. The instanton effect can be described as a backreaction modifying the geometry of the mirror configuration, in which the breaking of U(1) symmetries by the instanton translates into the recombination of gauge D-branes, which also directly generates the instanton-induced charged field theory operator. In this paper we describe the D-brane instanton backreaction in terms of a combinatorial operation in the bipartite dimer diagram of the original theory. Interestingly, the resulting theory is a general Bipartite Field Theory (BFT), defined by a bipartite graph tiling a general (possibly …

Crab Cavity Requirements For The Jefferson Lab Electron-Ion Collider, Salvador Isaac Sosa Güitrón

Physics Theses & Dissertations

An Electron-Ion Collider (EIC) has been proposed to be the next large facility to explore the dynamics of quarks and gluons inside nuclei. A conceptual design for a Jefferson Lab Electron-Ion Collider (JLEIC) is being developed. It is based on the CEBAF 12 GeV machine as a full energy electron beam injector. Two crucial requirements of JLEIC are high luminosity in the 10³⁴ cm^-2s^-1 range, and full acceptance detection of particles. The full acceptance requirement relies on having the beams collide at a relatively large crossing angle of 50 mrad. Such a large crossing angle, however, …