Daekyoung Kang
A5073907153- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Superconducting Materials and Applications
- Atomic and Molecular Physics
- Quantum, superfluid, helium dynamics
- Particle Accelerators and Free-Electron Lasers
- Nuclear physics research studies
- Astrophysics and Cosmic Phenomena
- Strong Light-Matter Interactions
- Quantum Information and Cryptography
- Spectroscopy and Laser Applications
- Radiation Detection and Scintillator Technologies
- Physics of Superconductivity and Magnetism
- Astronomy and Astrophysical Research
- Magnetic confinement fusion research
- Black Holes and Theoretical Physics
- Health and Well-being Studies
- Solar and Space Plasma Dynamics
- Advanced Thermodynamics and Statistical Mechanics
Fudan University
2018-2025
Korea University
2002-2024
Institute of Modern Physics
2018-2024
The Ohio State University
2007-2023
Auburn University
2023
Thomas Jefferson National Accelerator Facility
2022
University of Aveiro
2021
Los Alamos National Laboratory
2013-2018
Korea Research Institute of Standards and Science
2017
Seoul National University
2017
Systems consisting of identical bosons with a large scattering length satisfy universal relations determined by 2-body physics that are similar to those for fermions two spin states. They require the momentum distribution have large-momentum 1/k^4 tail and radio-frequency transition rate high-frequency 1/omega^{3/2} tail, both which proportional contact. Identical also additional 3-body involve contact, measures probability 3 particles being very close together. The coefficients contact in...
We present a new computation of $S$-wave color-singlet nonrelativistic QCD matrix elements for the $J/\ensuremath{\psi}$ and ${\ensuremath{\eta}}_{c}$. compute leading order in heavy-quark velocity $v$ relative ${v}^{2}$. Our is based on electromagnetic decay rates ${\ensuremath{\eta}}_{c}$ potential model that employs Cornell potential. include relativistic corrections to rates, resumming class all orders $v$, find they significantly increase values $v$. This could have important...
A set of universal relations between various properties any few-body or many-body system consisting fermions with two spin states and a large but finite scattering length have been derived by Shina Tan. We derive generalizations the Tan for two-channel model near Feshbach resonance that includes molecular state whose detuning energy controls length. use quantum field theory methods, including renormalization operator product expansion, to these relations. They reduce as is made increasingly large.
Universal relations that hold for any state provide powerful constraints on systems consisting of fermions with two spin states interacting a large scattering length. In radio-frequency (rf) spectroscopy, the mean shift in rf frequency and large-frequency tail transition rate are proportional to contact, which measures density pairs small separations. We show these universal can be derived extended by using short-time operator product expansion quantum field theory. This is general method...
We predict cross sections in deep inelastic scattering (DIS) for the production of two jets---one along proton beam direction created by initial-state radiation (ISR) and another final-state after hard collision. Our results include fixed-order corrections a summation large logarithms up to next-to-next-to-leading logarithmic accuracy resummed perturbation theory. make predictions three versions DIS event shape 1-jettiness, each which constrains hadronic final states be well collimated into...
We present two methods for computing dimensionally regulated nonrelativistic QCD heavy-quarkonium matrix elements that are related to the second derivative of wave function at origin. The first method makes use a hard-cutoff regulator as an intermediate step and requires knowledge only function. It involves significant cancellation is obstacle achieving high numerical accuracy. more direct yields result identical Gremm-Kapustin relation, but it limited in potential models. can be generalized...
It has been suggested in Ref. [A. E. Bondar and V. L. Chernyak, Phys. Lett. B 612, 215 (2005)] that the disagreement between theoretical calculations experimental observations for rate process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}+{\ensuremath{\eta}}_{c}$ at $B$ factories might be resolved by using light-cone method to take into account relative momentum of heavy-quark antiquark quarkonia. The result production cross section is almost an order-of-magnitude...
The COMPASS experiment at the CERN SPS has studied diffractive dissociation of negative pions into π−π−π+ final state using a 190 GeV/c pion beam hitting lead target. A partial wave analysis been performed on sample 420 000 events taken values squared 4-momentum transfer t′ between 0.1 and 1 GeV2/c2. well-known resonances a1(1260), a2(1320), π2(1670) are clearly observed. In addition, data show significant natural-parity exchange production resonance with spin-exotic quantum numbers JPC=1−+...
We present a LO evaluation of helicity densities valence, Δuv+Δdv, non-strange sea, Δu¯+Δd¯, and strange quarks, Δs (assumed to be equal Δs¯). They have been obtained from the inclusive asymmetry A1,d semi-inclusive asymmetries A1,dπ+, A1,dπ−, A1,dK+, A1,dK− measured in polarised deep inelastic muon–deuteron scattering. The full deuteron statistics COMPASS (years 2002–2004 2006) has used. data cover range Q2>1(GeV/c)2 0.004<x<0.3. Both are found good agreement with previous measurements....
In a recent experiment with ultracold trapped $^{85}\mathrm{Rb}$ atoms, Makotyn et al. studied quantum-degenerate Bose gas in the unitary limit where its scattering length is infinitely large. We show that observed momentum distributions are compatible universal relation expresses high-momentum tail terms of two-body contact ${C}_{2}$ and three-body ${C}_{3}$. determine densities for number density $n$ to be ${\mathcal{C}}_{2}\ensuremath{\approx}20{n}^{4/3}$...
We present a precise measurement of the deuteron longitudinal spin asymmetry A1d and spin-dependent structure function g1d at Q2<1(GeV/c)2 4×10−5<x<2.5×10−2 based on data collected by COMPASS experiment CERN during years 2002 2003. The statistical precision is tenfold better than that previous in this region. measured are found to be consistent with zero whole range x.
The 3-body recombination rate at threshold for distinguishable atoms with large negative pair scattering lengths is calculated in the zero-range approximation. only parameters this limit are 3 and Efimov parameter, which can be complex valued. We provide semi-analytic expressions cases of 2 or equal we obtain numerical results general case different lengths. Our result applied to three lowest hyperfine states Lithium-6 atoms. Comparisons recent experiments indications loss features...
We construct line shapes for the $X(3872)$, which generalize Flatt\'e and zero-range that have been considered previously. These are associated with scattering amplitudes exactly unitary real values of interaction parameters can be derived from a renormalizable quantum field theory. The new used to discriminate between alternative binding mechanisms in $X(3872)$ is generated either dynamically by charm-meson interactions or resonance near ${D}^{*0}{\overline{D}}^{0}$ threshold. If identified...
We present the centrality dependence of proton and deuteron rapidity distributions in Ru+Ru collisions at $400A\mathrm{MeV}.$ Data are compared with isospin quantum molecular dynamics (IQMD) calculations under various assumptions on nucleon-nucleon cross section medium. The spectra both particles can be reproduced by IQMD a free for most central collisions. ratio baryon asymmetric collision systems shows incomplete mixing partial transparency projectile target nuclei this beam energy.
For identical bosons with a large scattering length, the dependence of 3-body recombination rate on collision energy is determined in zero-range limit by universal functions single scaling variable. There are six for angular momentum zero and one function each higher partial wave. We calculate these solving Skorniakov--Ter-Martirosian equation. The results as good agreement previous from Schroedinger equation 4He atoms. can be used to at nonzero temperature. obtain an excellent fit data...
The gluon polarisation in the nucleon has been determined by detecting charm production via D0 meson decay to charged K and π polarised muon scattering off a longitudinally deuteron target. data were taken COMPASS Collaboration at CERN between 2002 2006 correspond an integrated luminosity of 2.8 fb−1. dominant underlying process is photon–gluon fusion cc¯ pair. A leading order QCD approach gives average 〈Δg/g〉x=−0.49±0.27(stat)±0.11(syst) scale μ2≈13(GeV/c)2 momentum fraction 〈x〉≈0.11....
A bstract The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energy. particularly predictive model for self-interactions is resonant short-range interactions with an S-wave scattering length much larger than range. velocity dependence cross section in such a provides excellent fit to self-interaction sections inferred from dark-matter halos galaxies and clusters if mass about 19 GeV 17 fm. Such makes...
We present a simple observation about soft amplitudes and functions appearing in factorizable cross sections ee , ep pp collisions that has not clearly been made previous literature, namely, the hemisphere appear event shape distributions e + − → dijets deep inelastic scattering (DIS), Drell–Yan (DY) processes are equal perturbation theory up to O ( α s 2 ) even though individual may have opposite sign imaginary parts due changing complex pole prescriptions eikonal propagators for incoming...
The leading-order parton processes that produce a dilepton with large transverse momentum predict the polarization should increase for almost any choice of quantization axis spin virtual photon. rate approach to complete depends on axis. We propose axes optimize approach. They are determined by and direction jet provides most balancing momentum.
A new narrow three-atom loss resonance associated with an Efimov trimer crossing the threshold has recently been discovered in a many-body system of ultracold $^{6}\mathrm{Li}$ atoms three lowest hyperfine spin states at magnetic field near 895 G. O'Hara and coworkers have used measurements three-body recombination rate this region to determine complex parameter physics. Using as input, we calculate universal predictions for spectrum above 600 G where all scattering lengths are large. We...
We present an analytic $$ \mathcal{O}\left({\alpha}_s\right) calculation of cross sections in deep inelastic scattering (DIS) dependent on event shape, 1-jettiness, that probes final states with one jet plus initial state radiation. This is the first entirely for a DIS shape section at this order. results differential and cumulative 1-jettiness sections, express both terms structure functions not only usual variables x, Q 2 but also τ. Combined previous log resummation, predictions are...