Reply to ``Comment on `Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions' ''

We demonstrate that in the process of deducing the constraint on the electroweak mixing angle $\theta_{W}$ in our paper, we have indeed been working with three mass scales while implementing (331) model.Comment: Revtex, 3pages, Reply to hep-ph/9902448, Submitted to Phys. Rev.

The Polarized and Unpolarized Photon Content of the Nucleon

The equivalent photon content of polarized and unpolarized nucleons (protons, neutrons), utilized in Weizs\"acker--Williams approximations, are presented. For this purpose a new expression for the elastic photon component of a polarized nucleon is derived. The inelastic photon components are obtained from the corresponding momentum evolution equations subject to the boundary conditions of their vanishing at some low momentum scale. The resulting photon asymmetries, important for estimating cross section asymmetries in photon induced subprocesses are also presented for some typical relevant momentum scales.Comment: LaTeX, 16 pages, 6 figure

Towards a first estimate of the gluon Sivers function from ANA_N data in pppp collisions at RHIC

Within a generalized parton model approach, with inclusion of spin and intrinsic transverse momentum effects, we show how the latest, highly precise, midrapidity data on the transverse single spin asymmetry measured in $pp\to\pi^0\, X$ by the PHENIX Collaboration at RHIC [1], can be used to get a first estimate on the still poorly known gluon Sivers distribution. To this end we also adopt the present information on the quark Sivers functions, as extracted from semi-inclusive deeply inelastic scattering data. This analysis updates a previous study by some of us where a first bound on this distribution was obtained [2].Comment: RevTex4, 10 pages, 7 eps figures. V2: discussion on the process dependence of the quark Sivers function, with two new plots (Fig. 4), added in Section II. One reference added. Results unchanged. Matches the published versio

Probing the transverse dynamics and polarization of gluons inside the proton at the LHC

Transverse momentum dependent gluon distributions encode fundamental information on the structure of the proton. Here we show how they can be accessed in heavy quarkonium production in proton-proton collisions at the LHC. In particular, their first determination could come from the study of an isolated J/? or ? particle, produced back to back with a photon

Delineating the polarized and unpolarized photon distributions of the nucleon in eN collisions

The production rates of lepton-photon and dimuon pairs at the HERA collider and the HERMES experiment are evaluated in the leading order equivalent photon approximation. It is shown that the production rates are sufficient to facilitate the extraction of the polarized and unpolarized equivalent photon distributions of the proton and neutron in the available kinematical regions. It is pointed out that these results indicate the possibility of additional, independent, tests concerning the unpolarized and polarized structure functions F_{1,2}^N and g_{1,2}^N, respectively, of the nucleon.Comment: Final version, to appear in Eur. Phys.

Comment on ``Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions''

We point out that if the majoron-like scheme is implemented within a 331 model, there must exist at least three different mass scales for the scalar vacuum expectation values in the model.Comment: 4 pages, no figures, Revtex. To be published in Physical Review

Probing the Perturbative NLO Parton Evolution in the Small-xx Region

A dedicated test of the perturbative QCD NLO parton evolution in the very small-$x$ region is performed. We find a good agreement with recent precision HERA-data for $F_2^p(x,Q^2)$, as well as with the present determination of the curvature of $F_2^p$. Characteristically, perturbative QCD evolutions result in a positive curvature which increases as $x$ decreases. Future precision measurements in the very small $x$-region, $x<10^{-4}$, could provide a sensitive test of the range of validity of perturbative QCDComment: Revised version, to appear in EPJ

Dijet imbalance in hadronic collisions

The imbalance of dijets produced in hadronic collisions has been used to extract the average transverse momentum of partons inside the hadrons. In this paper we discuss new contributions to the dijet imbalance that could complicate or even hamper this extraction. They are due to polarization of initial state partons inside unpolarized hadrons that can arise in the presence of nonzero parton transverse momentum. Transversely polarized quarks and linearly polarized gluons produce specific azimuthal dependences of the two jets that in principle are not suppressed. Their effects cannot be isolated just by looking at the angular deviation from the back-to-back situation, rather they enter jet broadening observables. In this way they directly affect the extraction of the average transverse momentum of unpolarized partons that is thought to be extracted. We discuss appropriately weighted cross sections to isolate the additional contributions.Comment: 15 pages, 2 figures; revised version, published in Phys. Rev.