Valery E. Lyubovitskij

A facility to search for hidden particles at the CERN SPS: the SHiP physics case.

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, [Formula: see text] and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals-scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

Hadronic molecule structure of the Y(3940) and Y(4140)

We report on further evidence that the Y(3940) and the recently observed Y(4140) are heavy hadron molecule states with quantum numbers J{sup PC}=0{sup ++}. The Y(3940) state is considered to be a superposition of D*{sup +}D*{sup -} and D*{sup 0}D*{sup 0}, while the Y(4140) is a bound state of D{sub s}*{sup +} and D{sub s}*{sup -} mesons. For the first time we give predictions for the strong Y(3940){yields}J/{psi}{omega}, Y(4140){yields}J/{psi}{phi} and radiative Y(3940)/Y(4140){yields}{gamma}{gamma} decay widths in a phenomenological Lagrangian approach. Results for the strong J/{psi}V (V={omega}, {phi}) decays clearly support the molecular interpretation of the Y(3940) and Y(4140). The alternative assignment of J{sup PC}=2{sup ++} is also tested, giving similar results for the strong decay widths.

Dilaton in a soft-wall holographic approach to mesons and baryons

We discuss a holographic soft-wall model developed for the description of mesons and baryons with adjustable quantum numbers n, J, L, S. This approach is based on an action which describes hadrons with broken conformal invariance and which incorporates confinement through the presence of a background dilaton field. We show that in the case of the bound-state problem (hadronic mass spectrum) two versions of the model with a positive and negative dilaton profile are equivalent to each other by a special transformation of the bulk field. We also comment on recent works which discuss the dilaton sign in the context of soft-wall approaches.

Light and heavy mesons in a soft-wall holographic approach

We study the mass spectrum and decay constants of light and heavy mesons in a soft-wall holographic approach, using the correspondence of string theory in Anti-de Sitter space and conformal field theory in physical space-time.

Hadronic atoms in QCD + QED

Abstract We review the theory of hadronic atoms in QCD+QED, based on a non-relativistic effective Lagrangian framework. We first provide an introduction to the theory, and then describe several applications: meson–meson, meson–nucleon atoms and meson–deuteron compounds. Finally, we compare the quantum field theory framework used here with the traditional approach, which is based on quantum-mechanical potential scattering.

Generalized parton distributions in AdS/QCD

The nucleon helicity-independent generalized parton distributions of quarks are calculated in the zero skewness case, in the framework of the anti-de Sitter/QCD model. The present approach is based on a matching procedure of sum rules relating the electromagnetic form factors to generalized parton distributions and anti-de Sitter modes.

Strong and radiative decays of the D(s0)*(2317) meson in the DK-molecule picture

We consider a possible interpretation of the new charm-strange meson D* s0 (2317) as a hadronic molecule-a bound state of D and K mesons. Using an effective Lagrangian approach, we calculate the strong D* s0 → D s π 0 and radiative D* s0 → D* s γ decays. A new impact related to the DK molecular structure of the D* s0 (2317) meson is that the presence of u(d) quarks in the D and K mesons gives rise to a direct strong isospin-violating transition D* s0 → D s π 0 in addition to the decay mechanism induced by η - π 0 mixing considered previously. We show that the direct transition dominates over the 17 - π 0 mixing transition in the D* s0 → D s π 0 decay. Our results for the partial decay widths are consistent with previous calculations.

Magnetic moments of heavy baryons in the relativistic three-quark model

The magnetic moments of ground state single, double and triple heavy baryons containing charm or bottom quarks are calculated in a relativistic three-quark model, which, in the heavy-quark limit, is consistent with heavy-quark effective theory and heavy hadron chiral perturbation theory. The internal quark structure of baryons is modeled by baryonic three-quark currents with a spin-flavor structure patterned according to standard covariant baryonic wave functions and currents used in QCD sum rule calculations.

Meson wave function from holographic models

We consider the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence, as has been suggested by Brodsky and Teramond. Two kinds of wave functions, obtained in different holographic Soft-Wall models, are discussed.

Sigma term physics in the perturbative chiral quark model

We apply the perturbative chiral quark model (PCQM) at one loop to analyse meson-baryon sigma-terms. Analytic expressions for these quantities are obtained in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, axial nucleon coupling, strong pion-nucleon form factor) and of only one model parameter (radius of the nucleonic three-quark core). Our result for the piN sigma term of about 45 MeV is in good agreement with the value deduced by Gasser, Leutwyler and Sainio using dispersion-relation techniques and exploiting the chiral symmetry constraints.