120507485
A Study Of Generalized Parton Distributions In Position Space
Abstract We present a study of the parton distributions in transverse position or impact parameter space for the chiral odd GPDs of a dressed quark in QED. We also present an analysis of a recent parametrization for the chiral even GPDs inside a proton. We also discuss the region of validity of the parametrizations based on a positivity condition.
124138685
Jet Production in $pp$ Collisions: Dependence on Jet Algorithm
119296844
Generalized parton distributions of the photon
Abstract We present a first calculation of the generalized parton distributions of the photon (both polarized and unpolarized) using overlaps of light-front wave functions at leading order in α and zeroth order in α s ; for non-zero transverse momentum transfer and zero skewness. We present the novel parton content of the photon in transverse position space.
55544629
Universality of TMD correlators
In a high-energy scattering process with hadrons in the initial state, color is involved. Transverse momentum dependent distribution functions (TMDs) describe the quark and gluon distributions in these hadrons in momentum space with the inclusion of transverse directions. Apart from the (anti)-quarks and gluons that are involved in the hard scattering process, additional gluon emissions by the hadrons have to be taken into account as well, giving rise to Wilson lines or gauge links. The TMDs involved are sensitive to the process under consideration and hence potentially nonuniversal due to these Wilson line interactions with the hard process; different hard processes give rise to different Wilson line structures. We will show that in practice only a finite number of universal TMDs have to be considered, which come in different linear combinations depending on the hard process under consideration, ensuring a generalized universality. For quarks this gives rise to three Pretzelocity functions, whereas for gluons a richer structure of functions arises.
118544091
Excitation of an Atom by Twisted Photons
Twisted photon states, or photon states with large ($> \hbar$) angular momentum projection in the direction of motion, can photoexcite atomic final states of differing quantum numbers. If the photon symmetry axis coincides with the center of an atom, there are known selection rules that require exact matching between the quantum numbers of the photon and the photoexcited states. The more general case of arbitrarily positioned beams relaxes the selection rules but produces a distribution of quantum numbers of the final atomic states that is novel and distinct from final states produced by plane-wave photons. Numerical calculations are presented using a hydrogen atom as an example.
116463245
The GPDs of The Photon
We report on a recent calculation of the generalized parton distributions (GPDs) of the photon when the momentum transfer in the transverse direction is non-zero. We use an overlap representation of the photon GPDs in terms of the photon light-front wave functions. We calculate the GPDs at leading order in electromagnetic coupling $\alpha$ and zeroth order in strong coupling $\alpha_s$. We consider also the case when the helicity of the photon is flipped. Fourier transform of the GPDs with respect to the transverse momentum transfer gives the parton distributions of the photon in impact parameter space.
118482889
Quantum Monte Carlo with Coupled-Cluster wave functions
ECT*, Villa Tambosi, I-38123 Villazzano (Trento), Italy(Dated: May 3, 2013)We introduce a novel many body method which combines two powerful many body techniques,viz., quantum Monte Carlo and coupled cluster theory. Coupled cluster wave functions are intro-duced as importance functions in a Monte Carlo method designed for the conﬁguration interactionframework to provide rigorous upper bounds to the ground state energy. We benchmark our methodon the homogeneous electron gas in momentum space. The importance function used is the coupledcluster doubles wave function. We show that the computational resources required in our methodscale polynomially with system size. Our energy upper bounds are in very good agreement withprevious calculations of similar accuracy, and they can be systematically improved by includinghigher order excitations in the coupled cluster wave function.
119254846
Variational theory of hot nucleon matter. II. Spin-isospin correlations and equation of state of nuclear and neutron matter
We apply the variational theory for fermions at finite temperature and high density, developed in an earlier paper, to symmetric nuclear matter and pure neutron matter. This extension generalizes to finite temperatures, the many body technique used in the construction of the zero temperature Akmal-Pandharipande-Ravenhall equation of state. We discuss how the formalism can be used for practical calculations of hot dense matter. Neutral pion condensation along with the associated isovector spin longitudinal sum rule is analyzed. The equation of state is calculated for temperatures less than 30 MeV and densities less than three times the saturation density of nuclear matter. The behavior of the nucleon effective mass in medium is also discussed.
6841250
Quantum Monte Carlo calculations of neutron matter with nonlocal chiral interactions.
We present fully nonperturbative quantum Monte Carlo calculations with nonlocal chiral effective field theory (EFT) interactions for the ground-state properties of neutron matter. The equation of state, the nucleon chemical potentials, and the momentum distribution in pure neutron matter up to one and a half times the nuclear saturation density are computed with a newly optimized chiral EFT interaction at next-to-next-to-leading order. This work opens the way to systematic order by order benchmarking of chiral EFT interactions and ab initio prediction of nuclear properties while respecting the symmetries of quantum chromodynamics.
100464553
Level densities of nickel isotopes: microscopic theory versus experiment
We apply a spin-projection method to calculate microscopically the level densities of a family of nickel isotopes $^{59-64}$Ni using the shell model Monte Carlo approach in the complete $pfg_{9/2}$ shell. Accurate ground-state energies of the odd-mass nickel isotopes, required for the determination of excitation energies, are determined using the Green's function method recently introduced to circumvent the odd particle-number sign problem. Our results are in excellent agreement with recent measurements based on proton evaporation spectra and with level counting data at low excitation energies. We also compare our results with neutron resonance data, assuming equilibration of parity and a spin-cutoff model for the spin distribution at the neutron binding energy, and find good agreement with the exception of $^{63}$Ni.
54611279
Number-conserving theory of nuclear pairing gaps: A global assessment
We study odd-even mass staggering of nuclei, also called pairing gaps, using a Skyrme self-consistent mean-field theory and a numerically exact treatment of the pairing Hamiltonian. We find that the configuration-space Monte Carlo method proposed by Cerf and Martin [Phys. Rev. C 47, 2610 (1993)] offers a practical computational procedure to carry out the numerical solutions in large-dimensional model spaces. Refitting the global strength of the pairing interaction for 443 neutron pairing gaps in our number-conserving treatment, we find the correction to the pairing correlation energies and pairing gaps to have rms values of 0.6 and 0.12 MeV, respectively. The exact treatment provides a significant improvement in the fit to experimental gaps, although it is partially masked by a larger rms error due to deficiencies in other aspects of the theory, such as the mean-field energy functional.