Related papers: Off-diagonal Helicity Density Matrix Elements for …
We review here the physics of purely leptonic decays of pi-, K-, D+, Ds+, and B- pseudoscalar mesons. The measured decay rates are related to the product of the relevant weak interaction based CKM matrix element of the constituent quarks…
We explore a scenario where Dark Matter (DM) couples to the Standard Model mainly via a scalar mediator ${\cal S}$ that is odd under a $Z_2$ symmetry, leading to interesting collider signatures. In fact, if linear interactions with the…
We study the pair production of charginos in e+e- collisions followed by the decay via R-parity violating LQD operators. We determine the complete matrix element squared for chargino decays via LQD or LLE operators. We find regions in MSSM…
The DELPHI detector at LEP is particularly suited for hadron identification and for the identification of b-initiated jets. This note presents recent results based on such characteristics.
Searches for pair-produced charginos, neutralinos and scalar fermions decaying via R-parity violating / /\' and /\'' couplings with the OPAL detector at LEP are presented at sqrt(s)=189 GeV. Partial updates using data up to the highest…
We use the available data on $<dN/dy>$ and $<\it{p}_T>$ for the identified hadrons including $\pi^{+}+\pi^{-}$, $K^{+}+K^{-}$, $p+\overline{p}$, $K^*(892)^0$ and $\varphi$-mesons, registered at midrapidity ($\vert y\vert < 0.5)$ in central…
A search for pair-produced vector-like quarks using events with exactly one lepton ($e$ or $\mu$), at least four jets including at least one $b$-tagged jet, and large missing transverse momentum is presented. Data from proton-proton…
Measurements of light hadron production in ultrarelativistic nuclear collisions provide essential insight into final-state effects arising from both hot and cold nuclear matter. They probe collective behavior, hadronization via…
The first evidence of spin alignment of vector mesons ($K^{*0}$ and $\phi$) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element $\rho_{00}$ is measured at midrapidity ($|y| <$ 0.5) in…
Vector mesons are key probes of the hot and dense state of strongly interacting matter produced in heavy ion collisions. Their dileptonic decay channel is particularly suitable for these studies, since dileptons have negligible final state…
The lepton pair production via the quark-antiquark annihilation subprocess in collisions of beam antiproton with the proton target at E_beam = 14 GeV (which corresponds to the center-of-mass energy of the p pbar system E_cm = 5.3 GeV) is…
We evaluate the cross sections for the production of vector mesons in exclusive ultraperipheral proton-ion collisions at LHC. We find that the rates are high enough to study the energy and momentum transfer dependence of vector mesons -…
Using a relativistic transport model to describe the expansion of the fire-cylinder formed in the initial stage of heavy-ion collisions at SPS/CERN energies, we study the production of dileptons with mass below about 1 GeV from these…
In reference to the recently observed high Q^2, large x events in deep-inelastic positron-proton scattering at HERA, various leptoquark and supersymmetric scenarios are discussed. We study the impact of virtual leptoquark or R-parity…
Continuing our previous study of Deeply Virtual Meson Production (DVMP) at twist-3 accuracy, we derive compact expressions for all helicity amplitudes. We perform a phenomenological analysis of the helicity-amplitude ratio…
We present a unified Dyson-Schwinger equation treatment of static and electromagnetic properties of pseudoscalar and vector mesons, and scalar and axial-vector diquark correlations, based upon a vector-vector contact-interaction. A basic…
A search is presented for the pair-production of heavy vector-like quarks in the lepton+jets final state using 140 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}= 13$ TeV collected with the ATLAS detector. The search is optimised for…
The complete density matrix for all polarization configurations in the process B--> t tbar, where B is an off--shell Z or photon and t is the top quark, is calculated numerically including oneloop QCD corrections, i.e. virtual and real…
Results on elastic vector meson production at HERA are presented in the framework of perturbative QCD. The energy dependence of the cross section for J/Psi photoproduction and for rho electroproduction is studied. A full polarisation…
We update present bounds on the helicity of the neutrinos produced in muon decay, including e+ e- -> fbar f LEP 2 data. These significantly reduce the limits derived from all the other electroweak precision data. In Standard Model…