Efficiency and timing performance of the MuPix7 high-voltage monolithic active pixel sensor

The MuPix7 is a prototype high voltage monolithic active pixel sensor with 103 times 80 um2 pixels thinned to 64 um and incorporating the complete read-out circuitry including a 1.25 Gbit/s differential data link. Using data taken at the DESY electron test beam, we demonstrate an efficiency of 99.3% and a time resolution of 14 ns. The efficiency and time resolution are studied with sub-pixel resolution and reproduced in simulations.Comment: 7 pages, 13 figures, submitted to Nucl.Instr.Meth.

Nuevos enfoques teóricos en los estudios sobre literatura del Siglo de Oro

Este trabajo parte del Encuentro de investigadores sobre “Nuevos enfoques teóricos en los estudios sobre Literatura del Siglo de Oro” desarrollado en el VIII Congreso de la AISO (Santiago de Compostela, 7-11 de julio de 2008).This work is part of the researchers encounter on ‘’New Theorical Approaches in the Studies on Golden Age Literature’’ developed in the VIII AISO Congress. (Santiago de Compostela, 7-11 July, 2008)

Probing Physics beyond the Standard Model: A Search for Lepton-Flavour-Violating Z→ℓτZ\to\ell\tau Decays with the ATLAS Experiment

In the Standard Model (SM), lepton flavour is conserved in all interactions. Hence, any observation of lepton flavour violation (LFV) would be an unambiguous sign of physics beyond the SM (BSM), and LFV processes are predicted by numerous BSM models. One way to search for LFV is in the decay of gauge bosons. In the search presented here, the decay of the $Z$ boson to an $e\tau$ or $\mu\tau$ pair is investigated using the full Run 2 $pp$ collision data set at $\sqrt{s}$ of 13 TeV recorded by the ATLAS experiment at the LHC. The analysis exploits $\tau$ decays into hadrons and - for the first time in this channel in ATLAS - into leptons. A key ingredient to the search is the usage of a neural net to differentiate between signal and background events in order to make optimum use of the data. Combined with about 8 billion $Z$ decays recorded by ATLAS in Run 2 of the LHC, the strongest constraints to date are set with $\mathcal{B}(Z\to e\tau)<5.0\times 10^{-6}$ and $\mathcal{B}(Z\to\mu\tau)<6.5\times 10^{-6}$ at 95% confidence level - finally superseding the limits set by the LEP experiments more than two decades ago

Probing Physics beyond the Standard Model: A Search for Lepton-Flavour-Violating Z→ℓτZ\to\ell\tau Decays with the ATLAS Experiment

In the Standard Model, lepton flavour is conserved in all interactions. Hence, any observation of lepton flavour violation would be an unambiguous sign of physics beyond the Standard Model as predicted in numerous extensions. One way to search for lepton flavour violation is in the decay of gauge bosons. In the search presented here, the decay of the $Z$ boson to an electron-tau or muon-tau pair is investigated using the full Run 2 proton-proton collision data set at a centre-of-mass energy of 13 TeV recorded by the ATLAS experiment at the Large Hadron Collider. The analysis exploits tau decays into leptons and is combined with a similar analysis on hadronically decaying tau leptons. A key ingredient to the search is the usage of a neural net to differentiate between signal and background events in order to make optimum use of the data. Combined with about 8 billion $Z$ decays recorded by ATLAS in Run 2, the strongest constraints to date are set with $\mathcal{B}(Z\to e\tau)<5.0\times 10^{-6}$ and $\mathcal{B}(Z\to\mu\tau)<6.5\times 10^{-6}$ at 95% confidence level - finally superseding the limits set by the OPAL and DELPHI experiments more than two decades ago

ATLAS Results with Beauty Mesons

A broad range of measurements involving $B$ mesons are performed with the ATLAS experiment at the Large Hadron Collider, of which a selection is discussed in this note. This includes a measurement of the relative $B_c^\pm$ to $B^\pm$ production cross section in $pp$ collisions at a centre-of-mass energy $\sqrt{s}$ of 8 TeV, as well as the latest results on the branching ratios of the rare decays $B^0_s\to\mu^+\mu^-$ and $B^0\to\mu^+\mu^-$ using $pp$ collisions recorded at $\sqrt{s}=$ 7, 8 and 13 TeV. Furthermore, accurate measurements of mixing and CP violation in $B_s^0 \to J/\psi\, \phi$ decays are performed. The latest results on the CP violating phase $\phi_s$ and other parameters describing the decay obtained at $\sqrt{s}=$ 7, 8 and 13 TeV are reported

ATLAS measurements of CP violation and rare decays processes with beauty mesons

The ATLAS experiment has a rich B physics program including measurements of CP violation in B meson decays and studies of rare FCNC decays of B mesons as sensitive probes of physics beyond the SM. In this talk, recent studies of the CP violating phase {\phi}_{s} in B^{0}_{s}{\to} J/{\Psi}{\phi} and of the rare decay of B^{0} and B^{0}_{s} to muon pairs are highlighted

Status of the Mu3e Experiment at PSI

The Mu3e experiment aims to search for the lepton-flavour violating decay $\mu^+\rightarrow\ \text{e}^+ \text{e}^+ \text{e}^-$ with a sensitivity to one signal decay in $10^{16}$ muon decays at a muon stopping rate of $2\times 10^9 \frac{\mu}{\text{s}}$. With currently available rates of $10^8 \frac{\mu}{\text{s}}$, a sensitivity on the branching ratio of $10^{-15}$ is the aim of the first phase. This will allow for tests of new physics models with enhanced branching ratios for lepton-flavour violating processes with an unprecedented precision. The experiment must be operated at very high muon rates all the while suppressing the background of the decay $\mu^+\rightarrow\ \text{e}^+ \text{e}^- \text{e}^+ \overline{\nu}_\mu \nu_\text{e}$ and accidental electron-positron combinations. Therefore, a tracking detector made of thin pixel sensors with additional scintillating fibres and tiles for precise time measurement will be built. The development of the subdetectors is ongoing while detector construction is still in preparation

Search for invisible Higgs-boson decays in events with vector-boson fusion signatures using 139 fb-1 of proton-proton data recorded by the ATLAS experiment

A direct search for Higgs bosons produced via vector-boson fusion and subsequently decaying into invisible particles is reported. The analysis uses 139 fb−1 of pp collision data at a centre-of-mass energy of s√ = 13 TeV recorded by the ATLAS detector at the LHC. The observed numbers of events are found to be in agreement with the background expectation from Standard Model processes. For a scalar Higgs boson with a mass of 125 GeV and a Standard Model production cross section, an observed upper limit of 0.145 is placed on the branching fraction of its decay into invisible particles at 95% confidence level, with an expected limit of 0.103. These results are interpreted in the context of models where the Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross section of weakly interacting massive particles and nucleons. Invisible decays of additional scalar bosons with masses from 50 GeV to 2 TeV are also studied, and the derived upper limits on the cross section times branching fraction decrease with increasing mass from 1.0 pb for a scalar boson mass of 50 GeV to 0.1 pb at a mass of 2 TeV

Search for new phenomena in final states with photons, jets and missing transverse momentum in pp collisions at √s =13 TeV with the ATLAS detector

A search for new phenomena has been performed in final states with at least one isolated high-momentum photon, jets and missing transverse momentum in proton--proton collisions at a centre-of-mass energy of 13~TeV. The data, collected by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of . The experimental results are interpreted in a supersymmetric model in which pair-produced gluinos decay into neutralinos, which in turn decay into a gravitino, at least one photon, and jets.No significant deviations from the predictions of the Standard Model are observed. Upper limits are set on the visible cross section due to physics beyond the Standard Model, and lower limits are set on the masses of the gluinos and neutralinos, all at 95\% confidence level