Search results for "QC770"
showing 10 items of 270 documents
Elliptic flow and $$R_{AA}$$ of $$\text {D}$$ mesons at FAIR comparing the UrQMD hybrid model and the coarse-graining approach
2019
The European physical journal / C Particles and fields C 79(1), 52 (2019). doi:10.1140/epjc/s10052-019-6537-6
Maximal Flavour Violation: a Cabibbo mechanism for leptoquarks
2018
We propose a mechanism that allows for sizeable flavour violation in quark-lepton currents, while suppressing flavour changing neutral currents in quark-quark and lepton-lepton sectors. The mechanism is applied to the recently proposed 4321 renormalizable model, which can accommodate the current experimental anomalies in $B$-meson decays, both in charged and neutral currents, while remaining consistent with all other indirect flavour and electroweak precision measurements and direct searches at high-$p_T$. To support this claim, we present an exhaustive phenomenological survey of this fully calculable UV complete model and highlight the rich complementarity between indirect and direct searc…
Effective Majorana mass matrix from tau and pseudoscalar meson lepton number violating decays
2018
An observation of any lepton number violating process will undoubtedly point towards the existence of new physics and indirectly to the clear Majorana nature of the exchanged fermion. In this work, we explore the potential of a minimal extension of the Standard Model via heavy sterile fermions with masses in the $[ 0.1 - 10]$ GeV range concerning an extensive array of "neutrinoless" meson and tau decay processes. We assume that the Majorana neutrinos are produced on-shell, and focus on three-body decays. We conduct an update on the bounds on the active-sterile mixing elements, $|U_{\ell_\alpha 4} U_{\ell_\beta 4}|$, taking into account the most recent experimental bounds (and constraints) a…
Spin alignment and violation of the OZI rule in exclusive ω and ϕ production in pp collisions
2014
Exclusive production of the isoscalar vector mesons $\omega$ and $\phi$ is measured with a 190 GeV$/c$ proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable $x_{F}$ of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on $x_{F}$ and on the invariant mass $M_{p\mathrm{V}}$ of the system formed by fast proton $p_\mathrm{fast}$ and vector meson $V$ is discussed in terms of diffractive production of $p_\mathrm{fast}V$ resonances in competition with central production. The measurement of the spin density matrix element $\rho_{00}$ of the vector mesons…
Measurement of azimuthal hadron asymmetries in semi-inclusive deep inelastic scattering off unpolarised nucleons
2014
Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS muon beam at $160$ GeV/c and a $^6$LiD target. The amplitudes of the three azimuthal modulations $\cos\phi_h$, $\cos2\phi_h$ and $\sin\phi_h$ were obtained binning the data separately in each of the relevant kinematic variables $x$, $z$ or $p_T^{\,h}$ and binning in a three-dimensional grid of these three variables. The amplitudes of the $\cos \phi_h$ and $\cos 2\phi_h$ modulations show strong kinematic dependencies both for positive and negative hadrons.
Monopole production via photon fusion and Drell-Yan processes: MADGRAPH implementation and perturbativity via velocity-dependent coupling and magneti…
2018
In this work we consider point-like monopole production via photon-fusion and Drell-Yan processes in the framework of an effective U(1) gauge field theory obtained from conventional models describing the interaction of spin 0, 1/2, 1 magnetically-charged fields with ordinary photons, upon electric-magnetic dualisation. We present arguments based on such dualities which support the conjecture of an effective monopole-velocity-dependent magnetic charge. For the cases of spin-1/2 and spin-1 monopoles, we also include a magnetic-moment term kappa, which is treated as a new phenomenological parameter and, together with the velocity-dependent coupling, allows for a perturbative treatment of the c…
Electroweak Higgs production with HiggsPO at NLO QCD
2017
We present the HiggsPO UFO model for Monte Carlo event generation of electroweak $VH$ and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet $p_T$ for new physics searches in VBF Higg…
Leptogenesis from oscillations and dark matter
2019
An extension of the Standard Model with Majorana singlet fermions in the 1–100 GeV range can explain the light neutrino masses and give rise to a baryon asymmetry at freeze-in of the heavy states, via their CP-violating oscillations. In this paper we consider extending this scenario to also explain dark matter. We find that a very weakly coupled B−L gauge boson, an invisible QCD axion model, and the singlet majoron model can simultaneously account for dark matter and the baryon asymmetry.
Spin-dependence of gravity-mediated dark matter in warped extra-dimensions
2021
We study the spin-dependence of Dark Matter (DM) particles which interact gravitationally with the Standard Model (SM) in an extra-dimensional Randall-Sundrum scenario. We assume that both the Dark Matter and the Standard Model are confined to the TeV (Infra-red) brane and only interact via gravitational mediators, namely Kaluza-Klein gravitons and the radion. We analyze the different DM annihilation channels and find that it is possible to achieve the presently observed relic abundance of Dark Matter, $\Omega_{\rm DM}$, within the freeze-out mechanism for DM particles of spin 0, 1/2 and 1. We study the region of the model parameter space for which $\Omega_{\rm DM}$ is achieved and compare …
Phenomenology of scotogenic scalar dark matter
2020
We reexamine the minimal Singlet + Triplet Scotogenic Model, where dark matter is the mediator of neutrino mass generation. We assume it to be a scalar WIMP, whose stability follows from the same $\mathbb{Z} _{2}$ symmetry that leads to the radiative origin of neutrino masses. The scheme is the minimal one that allows for solar and atmospheric mass scales to be generated. We perform a full numerical analysis of the signatures expected at dark matter as well as collider experiments. We identify parameter regions where dark matter predictions agree with theoretical and experimental constraints, such as neutrino oscillations, Higgs data, dark matter relic abundance and direct detection searche…