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Peter Cho

Publications and source records attributed to Peter Cho.

At least 19 recordsLinked to original sources

Object-Centric Data Synthesis for Category-level Object Detection

Deep learning approaches to object detection have achieved reliable detection of specific object classes in images. However, extending a model's detection capability to new object classes requires large amounts of annotated training data, which is costly and time-consuming to acquire, especially for long-tailed classes with insufficient representation in existing datasets. Here, we introduce the object-centric data setting, when limited data is available in the form of object-centric data (multi-view images or 3D models), and systematically evaluate the performance of four different data synthesis methods to finetune object detection models on novel object categories in this setting. The approaches are based on simple image processing techniques, 3D rendering, and image diffusion models, and use object-centric data to synthesize realistic, cluttered images with varying contextual coherence and complexity. We assess how these methods enable models to achieve category-level generalization in real-world data, and demonstrate significant performance boosts within this data-constrained experimental setting.

cs.CV

Low Energy Quantum System Simulation

A numerical method for solving Schrodinger's equation based upon a Baker-Campbell-Hausdorff (BCH) expansion of the time evolution operator is presented herein. The technique manifestly preserves wavefunction norm, and it can be applied to problems in any number of spatial dimensions. We also identify a particular dimensionless ratio of potential to kinetic energies as a key coupling constant. This coupling establishes characteristic length and time scales for a large class of low energy quantum states, and it guides the choice of step sizes in numerical work. Using the BCH method in conjunction with an imaginary time rotation, we compute low energy eigenstates for several quantum systems coupled to non-trivial background potentials. The approach is subsequently applied to the study of 1D propagating wave packets and 2D bound state time development. Failures of classical expectations uncovered by simulations of these simple systems help develop quantum intuition. Finally, we investigate the response of a Superconducting Quantum Interference Device (SQUID) to a time dependent potential. We discuss how to engineer the potential's energy and time scales so that the SQUID acts as a quantum NOT gate. The notional simulation we present for this gate provides useful insight into the design of one candidate building block for a quantum computer.

quant-ph

The Confining Phase Kahler Potential in SUSY QCD

We investigate the low energy structure of the Kahler potential in SUSY QCD with Nf=Nc+1 quark flavors. Since this theory's moduli space is everywhere smooth, a systematic power series expansion of its Kahler potential can be developed in terms of confined meson and baryon fields. Perturbation theory in the supersymmetric sigma model based upon a momentum expansion consistent with naive dimensional analysis and 1/Nf power counting exhibits some similarities with ordinary QCD chiral perturbation theory along with several key differences. We compute meson and baryon wavefunction renormalization as well as Kahler potential operator mixing to leading nontrivial order. We also deduce the asymptotic dependence of the lowest dimension operators' coefficients upon moduli space location along flat directions where the theory is Higgsed down to Nf-1=(Nc-1)+1 SUSY QCD. Although an exact form for the confining phase Kahler potential remains unknown, we find that some detailed Kahler sector information can nevertheless be derived from first principles.

hep-th

Misleading Anomaly Matchings?

We investigate the low energy dynamics of N=1 supersymmetric SO(N) gauge theories with a single symmetric tensor matter field. These theories exhibit non-trivial matching of global 't Hooft anomalies at the origin of moduli space. We argue that their quantum moduli spaces possess distinct Higgs and confining branches which touch at the origin in an interacting non-Abelian Coulomb phase. The matching of anomalies between microscopic degrees of freedom and colorless moduli therefore appears to be coincidental. We discuss a formal mathematical relation between the SO(N) model and an analogous Sp(2N) theory with a single antisymmetric matter field which provides an explanation for the anomaly matching coincidence.

hep-th

Moduli in Exceptional SUSY Gauge Theories

The low energy structures of N=1 supersymmetric models with E_6, F_4 and E_7 gauge groups and fundamental irrep matter contents are studied herein. We identify sets of gauge invariant composites which label all flat directions in the confining/Higgs phases of these theories. The impossibility of mapping several of these primary operators rules out previously conjectured exceptional self duals reported in the literature.

hep-th

Dual Descriptions of SO(10) SUSY Gauge Theories with Arbitrary Numbers of Spinors and Vectors

We examine the low energy structure of N=1 supersymmetric SO(10) gauge theory with matter chiral superfields in N_Q spinor and N_f vector representations. We construct a dual to this model based upon an SU(N_f+2N_Q-7) x Sp(2N_Q-2) gauge group without utilizing deconfinement methods. This product theory generalizes all previously known Pouliot-type duals to SO(N_c) models with spinor and vector matter. It also yields large numbers of new dual pairs along various flat directions. The dual description of the SO(10) theory satisfies multiple consistency checks including an intricate renormalization group flow analysis which links it with Seiberg's duality transformations. We discuss its implications for building grand unified theories that contain all Standard Model fields as composite degrees of freedom.

hep-th

More on Chiral-Nonchiral Dual Pairs

Expanding upon earlier work of Pouliot and Strassler, we construct chiral magnetic duals to nonchiral supersymmetric electric theories based upon SO(7), SO(8) and SO(9) gauge groups with various numbers of vector and spinor matter superfields. Anomalies are matched and gauge invariant operators are mapped within each dual pair. Renormalization group flows along flat directions are also examined. We find that confining phase quantum constraints in the electric theories are recovered from semiclassical equations of motion in their magnetic counterparts when the dual gauge groups are completely Higgsed.

hep-th

Exact Results in SO(11) SUSY Gauge Theories with Spinor and Vector Matter

We investigate the confining phase vacuum structure of supersymmetric SO(11) gauge theories with one spinor matter field and Nf \le 6 vectors. We describe several useful tricks and tools that facilitate the analysis of these chiral models and many other theories of similar type. The forms of the Nf=5 and Nf=6 quantum moduli spaces are deduced by requiring that they reproduce known results for SU(5) SUSY QCD along the spinor flat direction. After adding mass terms for vector fields and integrating out heavy degrees of freedom, we also determine the dynamically generated superpotentials in the Nf \le 4 quantum theories. We close with some remarks regarding magnetic duals to the Nf \ge 7 electric SO(11) theories.

hep-th

Symplectic SUSY Gauge Theories with Antisymmetric Matter

We investigate the confining phase vacua of supersymmetric $Sp(2\NC)$ gauge theories that contain matter in both fundamental and antisymmetric representations. The moduli spaces of such models with $\NF=3$ quark flavors and $\NA=1$ antisymmetric field are analogous to that of SUSY QCD with $\NF=\NC+1$ flavors. In particular, the forms of their quantum superpotentials are fixed by classical constraints. When mass terms are coupled to $W_{(\NF=3,\NA=1)}$ and heavy fields are integrated out, complete towers of dynamically generated superpotentials for low energy theories with fewer numbers of matter fields can be derived. Following this approach, we deduce exact superpotentials in $Sp(4)$ and $Sp(6)$ theories which cannot be determined by symmetry considerations or integrating in techniques. Building upon these simple symplectic group results, we also examine the ground state structures of several $Sp(4) \times Sp(4)$ and $Sp(6) \times Sp(2)$ models. We emphasize that the top-down approach may be used to methodically find dynamical superpotentials in many other confining supersymmetric gauge theories.

hep-th

Color-Singlet $ψ_Q$ Production at $e^+e^-$ Colliders

We calculate in closed form the complete ${\mathcal O}(α_s^2)$ color-singlet differential cross section for $e^+e^- \to γ^* \to ψ_Q+X$ scattering. The cross section reduces at high energies to a heavy quark fragmentation form. We find that the energy scale at which the approximate fragmentation result becomes reliable exceeds the $ψ_Q$ mass by more than an order of magnitude. We also discuss the color-singlet model's predictions for direct $J/ψ$ angular and energy distributions at CLEO.

hep-ph

Color-octet quarkonia production II

We calculate the lowest order hadronic cross sections for producing colored heavy quark-antiquark pairs in $L=S=0$ and $L=S=1$ configurations. Such $Q\Qbar[{}^1S_0^{(8)}]$ and $Q\Qbar[{}^3P_J^{(8)}]$ states hadronize into $ψ_\Q$ quarkonia at the same order in the NRQCD velocity expansion as previously considered $Q\Qbar[{}^3S_1^{(8)}]$ pairs. Their contributions to prompt Psi and Upsilon production at the Tevatron bring the shapes of theoretical transverse momentum distributions into line with recent CDF measurements. We find that the best fit values for the linear combinations of $Q\Qbar[{}^1S_0^{(8)}]$ and $Q\Qbar[{}^3P_J^{(8)}]$ long distance matrix elements which can be extracted from the data are generally consistent with NRQCD scaling rules.

hep-ph

$K_L \to π^0 e^+ e^-$ and $B \to X_s \ell^+ \ell^-$ Decay in the MSSM

The flavor changing neutral current processes $K_L \to π^0 e^+ e^-$, $B \to X_s e^+ e^-$ and $B \to X_s μ^+ μ^-$ are studied within the minimal supersymmetric extension of the Standard Model. We first examine the rates for these decay modes in the MSSM with a universal soft supersymmetry breaking sector at a Grand Unification scale. We later relax the universality condition and investigate the FCNC transitions in a more general class of models with negligible flavor violation in squark mixing matrices. We find that the MSSM prediction for the kaon channel's branching fraction differs from its Standard Model value by at most 30\% over the entire allowed parameter space. On the other hand, supersymmetric contributions could potentially enhance certain $B \to X_s \ell^+ \ell^-$ observables by more than 100\% relative to Standard Model expectations. The impact of supersymmetry upon the $B$ meson modes is strongly correlated with the MSSM value for the Wilson coefficient of the magnetic moment operator that mediates $B \to X_s γ$.

hep-ph

Prompt Upsilon and Psi Production at LEP

Color-octet contributions to quarkonia production at LEP are studied herein. The short distance formation of heavy quark-antiquark pairs in color-octet configurations via gluon fragmentation processes is significantly enhanced relative to the creation of color-singlet pairs via heavy quark fragmentation. But the subsequent long distance hadronization of these colored pairs into physical quarkonium bound states is suppressed compared to the nonperturbative evolution of their colorless counterparts. We find that the overall LEP rates for gluon fragmentation into prompt Upsilon and Psi vector bosons exceed those from heavy quark fragmentation. Inclusion of the dominant color-octet quarkonium production channel eliminates sizable discrepancies between previous predictions and recent measurements of prompt $Z \to \Jpsi+X$, $Z \to ψ'+X$ and $Z \to Υ+X$ branching fractions.

hep-ph

Color-octet quarkonia production

Gluon fragmentation represents the dominant source of high energy prompt quarkonia at hadron colliders. Fragmentation approximations break down, however, when a quarkonium's transverse momentum becomes comparable to its mass. In this paper, we identify a large class of color-octet diagrams that mediate quarkonia production at all energies and reduce to the dominant set of gluon fragmentation graphs in the high $p_\perp$ limit. They contribute to quarkonia differential cross sections at the same order as color-singlet diagrams and bring theoretical predictions for Upsilon and Psi production at the Tevatron into agreement with experimental measurements. Using recent CDF data, we extract numerical values for bottomonia and charmonia color-octet matrix elements which are consistent with NRQCD scaling rules. We also find that quarkonia generated via the color-octet mechanism are strongly polarized at low as well as high energies. Spin alignment measurements can thus test the color-octet quarkonia production picture.

hep-ph

Spin symmetry predictions for heavy quarkonia alignment

We investigate the implications of spin symmetry for heavy quarkonia production and decay. We first compare spin symmetry predictions for charmonia and bottomonia radiative transitions with data and find they agree quite well. We next use spin symmetry along with nonrelativistic QCD power counting to determine the leading order alignment of P and D-wave orthoquarkonia that are produced through gluon fragmentation. Finally, we discuss a mechanism which may resolve the current factor of 30 discrepancy between theoretical predictions and experimental measurements of prompt $ψ'$ production at the Tevatron. This mechanism involves gluon fragmentation to a subleading Fock component in the $ψ'$ wavefunction and yields 100\% transversely aligned $ψ'$'s to lowest order. Observation of such a large alignment would provide strong support for this resolution to the $ψ'$ problem.

hep-ph

Gluon fragmentation to $^1D_2$ quarkonia

Gluon fragmentation to heavy $J^{PC}=2^{-+}$ quarkonia is studied herein. We compute these D-wave states' polarized fragmentation functions and find that they are enhanced by large numerical prefactors. The prospects for detecting the lowest lying $^1D_2$ charmonium state at the Tevatron are discussed.

hep-ph

Searching for $G^3$ in $t \tbar$ Production

The triple gluon field strength operator $G^3$ represents the only genuinely gluonic CP conserving term which can appear at dimension-6 within an effective strong interaction Lagrangian. Previous studies of this operator have revealed that its effect on gluon scattering is surprisingly difficult to detect. In this article, we analyze the impact of $G^3$ upon top quark pair production. We find that it will generate observable cross section deviations from QCD at the LHC for even relatively small values of its coefficient. Furthermore, $G^3$ affects the transverse momentum distribution of the produced top quarks more strongly at high energies than dimension-6 four-quark and chromomagnetic moment terms in the effective Lagrangian. Top-antitop production at the LHC will therefore provide a sensitive and clean probe for the elusive triple gluon field strength operator.

hep-ph

Gluon fragmentation into polarized charmonium

Gluon fragmentation to $\chicJ(1P)$ followed by single photon emission represents the dominant source of prompt $J/Ψ$'s at the Tevatron for $p_\perp \gtap 6 \GeV$. Since fragmenting gluons are approximately transverse, their products are significantly polarized. We find that gluon fragmentation populates the helicity levels of $\chione$, $\chitwo$ and $J/Ψ$ according to $D_{\chione^{(h=0)}}: D_{\chione^{(|h|=1)}} \simeq 1:1$, $D_{\chitwo^{(h=0)}} : D_{\chitwo^{(|h|=1)}} : D_{\chitwo^{(|h|=2)}} \simeq 1:2.9:6.0$ and $D_{\J^{(h=0)}} : D_{\J^{(|h|=1)}} \simeq 1:3.4$. We also speculate that gluon fragmentation to the radially excited $\chitwo(2P)$ state followed by subsequent radiative decay could represent a large source of $ψ'(2S)$'s and potentially resolve the $ψ'$ deficit problem. A measurement of these states' polarizations would test this idea.

hep-ph