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Kresimir Kumericki

Publications and source records attributed to Kresimir Kumericki.

26 records · Page 2Linked to original sources
arXiv2011

Accessing GPDs from experiment --- potential of a high-luminosity EIC ---

We discuss modeling of generalized parton distributions (GPDs), their access from present experiments, and the phenomenological potential of an electron-ion collider. In particular, we present a comparison of phenomenological models of GPD H, extracted from hard exclusive meson and photon production. Specific emphasis is given to the utilization of evolution effects at moderate x_Bj in a future high-luminosity experiment within a larger Q^2 lever arm.

hep-ph↗
arXiv2010

Deeply virtual Compton scattering at small x_B and the access to the GPD H

We give a partonic interpretation for the deeply virtual Compton scattering (DVCS) measurements of the H1 and ZEUS collaborations in the small-x_B region in terms of generalized parton distributions. Thereby we have a closer look at the skewness effect, parameterization of the t-dependence, revealing the chromomagnetic pomeron, and at a model dependent access to the anomalous gravitomagnetic moment of nucleon. We also quantify the reparameterization of generalized parton distributions resulting from the inclusion of radiative corrections up to next-to-next-to-leading order. Beyond the leading order approximation, our findings are compatible with a `holographic' principle that would arise from a (broken) SO(2,1) symmetry. Utilizing our leading-order findings, we also perform a first model dependent dispersion relation fit of HERMES and JLAB DVCS measurements. From that we extract the generalized parton distribution H on its cross-over line and predict the beam charge-spin asymmetry, measurable at COMPASS.

hep-ph↗
arXiv2010

Towards a global analysis of generalized parton distributions

We discuss the complexity of GPD phenomenology, comment on the technological needs for a global analysis, and report on model and neural network fits to the photon electroproduction off unpolarized proton. We also point out that Radyushkin's double distribution ansatz is a `holographic' GPD model.

hep-ph↗
arXiv2009

The Isgur-Wise Function within a Modified Heavy-Light Chiral Quark Model

We consider the Isgur-Wise function xi(omega) within a new modified version of a heavy-light chiral quark model. While early versions of such models gave too small absolute value of the slope, namely xi'(1) of about -0.4 to -0.3, we show how extended version(s) may lead to values around -1, in better agreement with recent measurements. This is obtained by introducing a new mass parameter in the heavy quark propagator. We also shortly comment on the consequences for the decay modes B --> D D-bar.

hep-ph↗
arXiv2009

DVCS and the skewness effect at small x

We analyze small-x DVCS data using flexible GPD models and compare our outcome with the full Shuvaev transformation. We point out that the full Shuvaev transform is a model that is equivalent to a conformal GPD and a minimalist ``dual'' parameterization. Some mathematical subtleties of conformal representations are recalled. We also comment on a speculation of a factorization breakdown in DVCS.

hep-ph↗
arXiv2008

New Dipole Penguin Contribution to K --> pi pi decays

We point out that the standard chromomagnetic penguin dipole operator has a counterpart corresponding to off-shell momenta for external quarks. By employing the chiral quark model, we show that this new dipole penguin operator has the same bosonisation as the standard Q_6 operator. Accordingly, this new operator enlarges by ~ 5 % the referent Q_6 contribution, which gives the dominant contribution to the CP-violating ratio epsilon'/epsilon and also gives an important contribution to the Delta I = 1/2 amplitude.

hep-ph↗
arXiv2008

Sum rules and dualities for generalized parton distributions: is there a holographic principle?

To leading order approximation, the physical content of generalized parton distributions (GPDs) that is accessible in deep virtual electroproduction of photons or mesons is contained in their value on the cross-over trajectory. This trajectory separates the t-channel and s-channel dominated GPD regions. The underlying Lorentz covariance implies correspondence between these two regions through their relation to GPDs on the cross-over trajectory. This point of view leads to a family of GPD sum rules which are a quark analogue of finite energy sum rules and it guides us to a new phenomenological GPD concept. As an example, we discuss the constraints from the JLab/Hall A data on the dominant u-quark GPD H. The question arises whether GPDs are governed by some kind of holographic principle.

hep-ph↗