arXiv subjects

Tommaso Pajero

Publications and source records attributed to Tommaso Pajero.

5 recordsLinked to original sources

arXiv2025

The Timepix4 Beam Telescope

The spatial and temporal performance of a telescope system comprising planar silicon sensors bump-bonded to Timepix4-v2 ASICs are assessed at the CERN SPS using a $180$~GeV/$c$ mixed hadron beam. The pointing resolution at the centre of the telescope is $2.3 \pm 0.1\;\mathrm{μm}$ and $2.4 \pm 0.1\mathrm{μm}$ in x and y directions, respectively. The temporal resolution for the combined timestamps on a track using only the information from the Timepix4 planes is found to be $92 \pm 5$~ps. The telescope is extensively described including its data acquisition system and dedicated software as well as the corrections applied to the raw measurements.

hep-ex↗

arXiv2022

Reconstruction of charged tracks with Timepix4 ASICs

The design of a detector system comprised of four silicon sensors bump-bonded to Timepix4 ASICs is described together with its data acquisition system, operational infrastructure, and dedicated software. The spatial and temporal performance of the system are assessed with a 180 GeV/c mixed hadron beam at the CERN SPS and reported in detail. Particle tracks are reconstructed using time-space measurements from the four detector planes. The spatial hit resolution is assessed to be $(15.5\pm 0.5)$ $μ$m and $(4.5\pm0.3)$ $μ$m for 100 and 300 $μ$m thick sensors, respectively. The timestamps from the detectors are also measured with fine precision, yielding time resolutions of $(452\pm10)$ ps, $(420\pm10)$ ps, $(639\pm10)$ ps, $(631\pm10)$ ps for the two 100 and two 300 $μ$m thick sensors respectively. These measurements are combined to a track time resolution of $(340\pm 5)$ ps.

physics.ins-det↗

arXiv2022

Recent advances in charm mixing and $CP$ violation at LHCb

After playing a pivotal role in the birth of the Standard Model in the 70's, the study of charm physics has undergone a revival during the last decade, triggered by a wealth of precision measurements from the charm and $B$ factories, and from the CDF and especially the LHCb experiments. In this article, we sum up how the unique phenomenology of charmed hadrons can be used to test the Standard Model and we review the latest measurements performed in this field by the LHCb experiment. These include the historic first observations of $CP$ violation and of a nonzero mass difference between the charmed neutral-meson mass eigenstates, the most precise determination of their decay-width difference to date, and a search for time-dependent $CP$ violation reaching the unprecedented precision of $10^{-4}$. These results challenge our comprehension of nonperturbative strong interactions, and their interpretation calls for further studies on both the theoretical and experimental sides. The upcoming upgrades of the LHCb experiment will play a leading role in this quest.

hep-ex↗

arXiv2022

Mixing and $CP$ violation in $D^0 \to K^- π^+$ decays

We review the experimental methods to measure mixing and time-dependent $C\!P$ violation in $D^0$ decays into two hadrons. While these phenomena are usually neglected for $D^0 \to K^- π^+$ decays, this approximation is not always justified. In particular, it produces a bias on the measurement of the parameter $y_{CP}$, when this is performed by relying on $D^0 \to K^- π^+$ decays as a normalisation channel, whose size is around 40% of the precision of the current world average. Finally, we estimate the sensitivity to the weak mixing phases achievable by studying $D^0 \to K^- π^+$ and untagged $D \to K^- π^+$ decays, where $D$ stands for either of the $D^0$ and $\bar{D}^0$ mesons. Contrary to Cabibbo-suppressed $D^0 \to h^+ h^-$ decays, these decay channels allow to measure these phases without final-state dependent nuisance contributions from the decay amplitudes, but their sensitivity is lower by a factor of six.

hep-ph↗

arXiv2019

Measurements of time-dependent $C\!P$ violation and mixing in charm at LHCb

The LHCb experiment has opened the possibility to test mixing and $C\!P$ violation in the charm sector with unprecedented precision thanks to the huge number of charm hadron decays collected, $\mathcal{O}(10^8)$. The first observation of $C\!P$ violation in the decay of charm quarks in March 2019 has been a fundamental achievement. The latest LHCb measurements in the complementary sectors of mixing and time-dependent $C\!P$ violation are illustrated in these proceedings. In particular, a new measurement of the $C\!P$ violation parameter $A_Γ$ with 2015--2016 data that was presented for the first time at this conference is described. In the last section, prospects are given for the improvements in precision expected in the next few years.

hep-ex↗