Exchange and correlation effects on drag in low density electron bilayers: Coulomb and virtual-optical-phonon-mediated electron-electron interaction

We investigate the effect of exchange and correlation (xc) in low-density electron bilayers. Along with the direct Coulomb interaction, the effective electron-electron interaction mediated by the exchange of virtual polar optical (PO) phonons is considered. We find that the introduction of xc corrections results in a significant enhancement of the transresistivity and qualitative changes in its temperature dependence. The virtual PO-phonon contribution behaves similarly to the Coulomb drag and reduces noticeably the total drag thereby resulting in a better agreement with the recent experimental findings.Comment: 5 pages, 4 figures, Int. Conf. EP2DS-1

Measurements of Electroweak Top Production at the LHC

The production of a single top quark at LHC may occur through charged-current electroweak interactions, i.e. via three different processes: the s-channel exchange of a virtual W boson, the t-channel exchange of a virtual W boson and the associated production of a top quark and a W boson (tW). In this paper a review of the measurements of the single-top production made both at ATLAS and CMS will be shown.Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 201

Pion dominance in RPV SUSY induced neutrinoless double beta decay

At the quark level there are basically two types of contributions of R-parity violating SUSY (RPV SUSY) to neutrinoless double beta decay: the short-range contribution involving only heavy virtual superpartners and the long-range one with the virtual squark and neutrino. Hadronization of the effective operators, corresponding to these two types of contributions, may in general involve virtual pions in addition to the close on-mass-shell nucleons. It is known that the short-range contribution is dominated by the pion exchange. In the present paper we show that this is also true for the long-range RPV SUSY contribution and, therefore, the RPV SUSY contributes to the neutrinoless double beta decay dominantly via charged pion exchange between the decaying nucleons.Comment: 7 pages, 1 figure. Minor corrections, several comments and references adde

Laser-catalyzed spin-exchange process in a Bose-Einstein condensate

We show theoretically that it is possible to optically control collective spin-exchange processes in spinor Bose condensates through virtual photoassociation. The interplay between optically induced spin exchange and spin-dependent collisions provides a flexible tool for the control of atomic spin dynamics, including enhanced or inhibited quantum spin oscillations, the optically-induced ferromagnetic-to-antiferromagnetic transition, and coherent matter-wave spin conversion.Comment: 4 pages, 4 figure

Deep inelastic scattering and "elastic" diffraction

We examine the total cross section of virtual photons on protons, $\sigma_{\gamma^* p}(W^2,Q^2)$, at low $x \cong Q^2/W^2 \ll 1$ and its connection with ``elastic'' diffractive production $\gamma^*_{T,L}p \to X^{J=1}_{T,L} p$ in the two-gluon exchange dynamics for the virtual forward Compton scattering amplitude. Solely based on the generic structure of two-gluon exchange, we establish that the cross section is described by the (imaginary part of the) amplitude for forward scattering of $q \bar q$ vector states, $(q \bar q)^{J=1}_{T,L} p \to (q \bar q)^ {J=1}_{T,L} p$. The generalized vector dominance/color dipole picture (GVD/CDP) is accordingly established to only rest on the two-gluon-exchange generic structure. This is explicitly seen by the sum rules that allow one to directly relate the total cross section to the cross section for elastic diffractive forward production, $\gamma^*_{T,L} p\to (q \bar q)^{J=1}_{T,L} p$, of vector states.Comment: 24 pages, latex file with three eps figures. BI-TP 2002/2

The virtual photon approximation for three-body interatomic Coulombic decay

Interatomic Coulombic decay (ICD) is a mechanism which allows microscopic objects to rapidly exchange energy. When the two objects are distant, the energy transfer between the donor and acceptor species takes place via the exchange of a virtual photon. On the contrary, recent ab initio calculations have revealed that the presence of a third passive species can significantly enhance the ICD rate at short distances due to the effects of electronic wave function overlap and charge transfer states [Phys. Rev. Lett. 119, 083403 (2017)]. Here, we develop a virtual photon description of three-body ICD, showing that a mediator atom can have a significant influence at much larger distances. In this regime, this impact is due to the scattering of virtual photons off the mediator, allowing for simple analytical results and being manifest in a distinct geometry-dependence which includes interference effects. As a striking example, we show that in the retarded regime ICD can be substantially enhanced or suppressed depending on the position of the ICD-inactive object, even if the latter is far from both donor and acceptor species

SUSY-QCD Corrections to Higgs Boson Production at Hadron Colliders

We analyze the next-to-leading order SUSY-QCD corrections to the production of Higgs particles at hadron colliders in supersymmetric extensions of the Standard Model. Besides the standard QCD corrections due to gluon exchange and emission, genuine supersymmetric corrections due to the virtual exchange of squarks and gluinos are present. At both the Tevatron and the LHC, these corrections are found to be small in the Higgs-strahlung, Drell-Yan-like Higgs pair production and vector boson fusion processes.Comment: 11 pages, latex, 3 figures, numerical analysis extended, one figure and one reference adde

On the coupling of two quantum dots through a cavity mode

The effective coupling of two distant quantum dots through virtual photon exchange in a semiconductor microcavity is studied. The experimental conditions for strong coupling and its manifestation in the spectra of emission are analyzed.Comment: 2 pages, 1 figur