Kresimir Kumericki

Deeply virtual Compton scattering at small

Abstract 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.

x_B

Abstract Combining dispersion and operator product expansion techniques, we derive the conformal partial wave decomposition of the virtual Compton scattering amplitude in terms of complex conformal spin to twist-two accuracy. The perturbation theory predictions for the deeply virtual Compton scattering (DVCS) amplitude are presented in next-to-leading order for both conformal and modified minimal subtraction scheme. Within a conformal subtraction scheme, where we exploit predictive power of conformal symmetry, the radiative corrections are presented up to next-to-next-to-leading order accuracy. Here, because of the trace anomaly, the mixing of conformal moments of generalized parton distributions (GPD) at the three-loop level remains unknown. Within a new proposed parameterization for GPDs, we then study the convergence of perturbation theory and demonstrate that our formalism is suitable for a fitting procedure of DVCS observables.

and the access to the GPD H

We propose a new seesaw model based on a fermionic hypercharge-zero weak quintuplet in conjunction with an additional scalar quadruplet which attains

Towards a fitting procedure for deeply virtual Compton scattering at next-to-leading order and beyond

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.

TeV-scale seesaw mechanism with quintuplet fermions

We utilize the DVCS asymmetry measurements of the HERMES collaboration for access to Compton form factors in the deeply virtual regime and to generalized parton distributions. In particular, the (almost) complete measurement of DVCS observables allows us to map various asymmetries into the space of Compton form factors, where we still rely in this analysis on dominance of twist-two associated Compton form factors. We compare this one-to-one map with local Compton form factor fits and a model dependent global fit.

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

Abstract.We review the phenomenological framework for accessing Generalized Parton Distributions (GPDs) using measurements of Deeply Virtual Compton Scattering (DVCS) from a proton target. We describe various GPD models and fitting procedures, emphasizing specific challenges posed both by the internal structure and properties of the GPD functions and by their relation to observables. Bearing in mind forthcoming data of unprecedented accuracy, we give a set of recommendations to better define the pathway for a precise extraction of GPDs from experiment.

HERMES impact for the access of Compton form factors

A bstractWe examine the stability of minimal dark matter (MDM) particle-candidates in the setup in which they participate in radiative neutrino (Rν) masses. We first point out the existence of an additional renormalizable term in recently proposed RνMDM Lagrangian, which violates the claimed accidental Z2 symmetry and spoils the stability of the fermionic MDM quintuplet component. We then explore the viability of RνMDM variants based on scalar MDM multiplets. There are ubiquitous super-renormalizable terms in the scalar potential which make these scalar multiplets unstable.

GPD phenomenology and DVCS fitting - Entering the high-precision era

We study the LHC potential for discovering TeV-scale SU(2)L 5plet fermions introduced recently to explain small neutrino masses. We show that the Drell-Yan production and the decays of new exotic � leptons are testable at the LHC. Their production is abundant due to nontrivial electroweak gauge charges. For 1 fb −1 of integrated luminosity at the present LHC √ s = 7 TeV, there can be 270 �-� pairs produced for M� = 400 GeV. Besides producing same-sign dilepton events, they could lead, due to a chosen small mixing between heavy and light leptons, to ∼10 golden decays � +++ (� +++ ) → W ± W ± l ± with a specific decay signature.

Critique of Fermionic RνMDM and its Scalar Variants

We have generated a parametrization of the Compton form factor (CFF)

Exotic Seesaw-Motivated Heavy Leptons at the LHC

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