Few-Body Systems

List of Papers (Total 127)

Studies of Deuteron Breakup Reactions in Deuteron–Deuteron Collisions at 160 MeV with BINA

A rich set of differential cross section of the three-body $$^{2}$$H(d,dp)n breakup reaction at 160 MeV deuteron beam energy has been measured over a large range of the available phase space. The experiment was performed at KVI in Groningen, the Netherlands, using the BINA detector. The cross-section data for the breakup reaction have been normalized to the simultaneously...

Efimov States in an Ultracold Gas: How it Happened in the Laboratory

In the year 2005, we obtained first evidence for the existence of weakly bound quantum states of three resonantly interacting particles, as predicted 35 years earlier by Vitaly Efimov. In our laboratory, the striking signature of an Efimov state was a giant three-body loss resonance observed in a gas of cesium atoms that was evaporatively cooled to temperatures of about 10...

Application of Semilocal Coordinate-Space Regularized Chiral Forces to Elastic Nd Scattering and Breakup

We solve three-nucleon (3N) Faddeev equations with nucleon–nucleon (NN) and three-nucleon forces (3NF) derived consistently in the framework of chiral perturbation theory, taking the semilocal coordinate-space regularized chiral N$$^4$$LO NN potential supplemented by the chiral N$$^2$$LO 3NF regularized in the same way. Based on these solutions the nucleon–deuteron (Nd) elastic...

Constituent-Quark Model with Pionic Contributions: Electromagnetic $${\varvec{N\rightarrow \varDelta }}$$ Transition

We report on ongoing work to determine the pion-cloud contribution to the electromagnetic $$N\rightarrow \varDelta$$ transition form factors. The starting point is an SU(6) spin-flavor symmetric constituent-quark model with instantaneous confinement that is augmented by dynamical pions which couple directly to the quarks. This system is treated in a relativistically invariant...

From Few to Many Body Degrees of Freedom

Here, I focus on the use of microscopic, few-body techniques that are relevant in the many-body problem. These methods can be divided into indirect and direct. In particular, indirect methods are concerned with the simplification of the many-body problem by substituting the full, microscopic interactions by pseudopotentials which are designed to reproduce collisional information...

Evaluating Polarization Data

A method is presented, which ensures that different polarization observables describing one reaction channel are consistent with each other. Using the connection of the observables to the same underlying reaction amplitudes, a constrained estimate of the observables is carried out using a Markov Chain Monte Carlo method. Initial results indicate that the new estimates are...

A New Feature of the Efimov-Like Structure in the Hadron System: Long-Range Force as a Recoil Effect

On the three-body kinematics, we investigate the threshold behavior which appears not only at the three-body break-up threshold (3BT), but also at the quasi two-body threshold (Q2T) for the reactions: $$A+(BC)\rightarrow A+B+C$$, and $$(ABC)\rightarrow A+(BC)$$, respectively. Recently, the author proposed a general particle $${transfer}$$ (GPT) potential which appears, not only...

Entanglement in Spatial Adiabatic Processes for Interacting Atoms

We study the dynamics of the non-classical correlations for few atom systems in the presence of strong interactions for a number of recently developed adiabatic state preparation protocols. We show that entanglement can be created in a controlled fashion and can be attributed to two distinct sources, the atom–atom interaction and the distribution of atoms among different traps.

The 3D Entangled Structure of the Proton: Transverse Degrees of Freedom in QCD, Momenta, Spins and More

Light-front quantized quark and gluon states (partons) play a dominant role in high energy scattering processes. Initial state hadrons are mixed ensembles of partons, while produced pure partonic states appear as mixed ensembles of hadrons. The transition from collinear hard physics to the 3D structure including partonic transverse momenta is related to confinement which links...

Wilson Lines and Webs in Higher-Order QCD

Wilson lines have a number of uses in non-abelian gauge theories. A topical example in QCD is the description of radiation in the soft or collinear limit, which must often be resummed to all orders in perturbation theory. Correlators involving a pair of Wilson lines are known to exponentiate in terms of special Feynman diagrams called “webs”. I will show how this language can be...

Experimentally Accessible Invariants Encoded in Interparticle Correlations of Harmonically Trapped Ultra-cold Few-Fermion Mixtures

A system of a two-flavour mixture of ultra-cold fermions confined in a one-dimensional harmonic trap is studied. Using the well-known properties of the centre-of-mass frame we present a numerical method of obtaining energetic spectra in this frame for an arbitrary mass ratio of fermionic species. We identify a specific invariant encoded in many-body correlations which may be...

Hyperspherical Harmonics Expansion on Lagrange Meshes for Bosonic Systems in One Dimension

A one-dimensional system of bosons interacting with contact and single-Gaussian forces is studied with an expansion in hyperspherical harmonics. The hyperradial potentials are calculated using the link between the hyperspherical harmonics and the single-particle harmonic-oscillator basis while the coupled hyperradial equations are solved with the Lagrange-mesh method. Extensions...

Symmetries for Light-Front Quantization of Yukawa Model with Renormalization

In this work we discuss the Yukawa model with the extra term of self-interacting scalar field in $$D=1+3$$ dimensions. We present the method of derivation the light-front commutators and anti-commutators from the Heisenberg equations induced by the kinematical generating operator of the translation $$P^{+}$$. Mentioned Heisenberg equations are the starting point for obtaining...

Heavy-Ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell–Yan Production

We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that $$\varUpsilon (nS)$$, $$J/\psi$$ and...

Three-Body Halo States in Effective Field Theory: Renormalization and Three-Body Interactions in the Helium-6 System

In this paper we study the renormalization of Halo effective field theory applied to the Helium-6 halo nucleus seen as an $$\alpha$$–neutron–neutron three-body state. We include the $$0^+$$ dineutron channel together with both the $$3/2^-$$ and $$1/2^-$$ neutron–$$\alpha$$ channels into the field theory and study all of the six lowest-order three-body interactions that are...

Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)

The measurement of Single Transverse-Spin Asymmetries, $$A_N$$, for various quarkonium states and Drell–Yan lepton pairs can shed light on the orbital angular momentum of quarks and gluons, a fundamental ingredient of the proton-spin puzzle. The AFTER@LHC proposal combines a unique kinematic coverage and large luminosities thanks to the Large Hadron Collider beams to deliver...

Physical and Nonphysical Modes in the Light Front Formulation for the LC Gauge and the Lorentz Gauge Conditions

The models with free vector fields are analyzed on the light-front hypersurface. The massive vector model—Proca model—can be quantized unambiguously within the novel LF procedure, though it leads to singular terms in $$x^{+}$$ coordinate. Also the modified models, where the Lorentz condition and the LC gauge conditions are explicitly induced by the Lagrange multipliers, are...

Meson Spectroscopy from Lattice QCD

Some recent progress in using lattice QCD to perform first-principles calculations of the spectra of mesons is discussed. In particular, I highlight some new results on resonances, near-threshold states and related scattering phenomena—this is a theoretically and experimentally interesting area where we have made significant advances in the last few years.

Relativistic Model of Hamiltonian Renormalization for Bound States and Scattering Amplitudes

We test the renormalization group procedure for effective particles on a model of fermion–scalar interaction based on the Yukawa theory. The model is obtained by truncating the Yukawa theory to just two Fock sectors in the Dirac front form of Hamiltonian dynamics, a fermion, and a fermion and a boson, for the purpose of simple analytic calculation that exhibits steps of the...

Production of $$\varvec{\eta }_{\varvec{c}}, \varvec{\chi }_{\varvec{c}}$$ and $$\varvec{\chi }_{\varvec{b}}$$ Mesons in Proton–(Anti)Proton Collisions

A multitude of precise measurements of $$J/\psi , \psi (2S)$$ and $$\Upsilon (nS)$$ ($$\hbox {n} = 1, 2, 3$$) production cross sections and polarizations have been conducted in recent years. These make the investigation of feed-down decays from heavier states crucial to fully comprehend their production mechanisms. Also the study of new, so far unmeasured quarkonium states is...

Invariant Coordinates in Breakup Reactions

Systematic experimental studies of few-nucleon systems expose various dynamical ingredients which play an important role in correct description of observables, such as three-nucleon force, Coulomb force and relativistic effects. A large set of existing experimental data for $$^1H(d, p p)n$$ reaction allows for systematic investigations of these dynamical effects, which vary with...

Parametrization of the Transverse Momentum Dependent Light-Front Correlator for Gluons

We study the transverse momentum dependent light-front correlator for gluons. At the operator level this is expressed as a matrix element containing nonlocal field strength operators and gauge links bridging the nonlocality. We parametrize the leading (twist-2) gluon–gluon correlator in terms of transverse momentum dependent distribution functions for unpolarized, vector and...