Recent hints of lepton flavour universality violation motivate searches for lepton flavour violating b-hadron decays. The LHCb experiment is particularly well suited for for these searches due to its large acceptance, high trigger efficiency and excellent tracking and particle identification capabilities. Recent results from LHCb on searches for the lepton flavour violating decays...
The Lepton Flavour Universality (LFU) anomalies are currently one of the hottest topics in the particle physics community. A combination of recent results from LHCb, Belle and BaBar from semileptonic B decays have shown a discrepancy from the Standard Model prediction of ≈ 4 σ. I will review the latest lepton universality tests with semileptonic B mesons and present the prospects for an...
One of the fundamental properties of the Standard Model (SM) is lepton flavour universality (LFU): particles couple equally to the three lepton generations. Rare decays governed by the $b \to s \ell^+ \ell^-$, which are loop- and CKM-suppressed, are extremely sensitive to New Physics scenarios introducing particles preferentially coupling to the second or third generations, and they have been...
The sensitivity of the decay $B^{0} \to K^{*0} \mu^{+}\mu^{-}$ to effects of beyond the Standard Model is well know. An anomalous behaviour in angular and branching fraction analyses of this decays has been reported, notably in one of the observables with reduced theoretical uncertainties, $P^{\prime}_{5}$. However, the vector-like nature of this pattern could be also explained by...
The equivalence of the three lepton families (except for their mass), known as lepton flavour universality (LFU), is a cornerstone of the Standard Model (SM), which can be violated in New Physics (NP) models by particles that couple preferentially to certain generations of leptons. In the last years, hints of LFU violation have appeared in both tree-level $b\to cl\nu$ and rare $b\to s\ell\ell$...
Measuring the top quark Yukawa coupling is an important test of the standard model (SM) of particle physics and the production of a Higgs boson in association with top quarks (ttH) is the only channel that allows a direct measurement of this SM parameter. This talk will focus on a search for ttH where the Higgs boson decays to bottom quarks and the top quark pair decays hadronically. The data...
Limits on the top squark mass from the LHC experiments have reached the TeV scale in the most favourable scenarios. More experimentally challenging models are now being investigated, such as scenarios predicting complex decay chains and compressed mass spectra.
In this context, the prospects for an ATLAS search for top squark pair production in events with either a Z or a Higgs boson, with the...
We present a search for direct bottom squark pair production using the full 2015-2017 ATLAS dataset in final states containing a large number of b-tagged jets and missing transverse energy. Naturalness considerations suggest that the masses of the superpartners of the third-generation quarks should be around the TeV scale and thus would be produced at a considerable rate at LHC. Depending upon...
In 2012, the ATLAS and CMS Collaborations announced the discovery of a new state with a mass around 125 GeV, compatible with the Standard Model Higgs boson. The measurements of this new particle’s properties are important to test the predictions of the Standard Model.
A measurement of the Higgs-beauty quark coupling through the Higgs boson production associated with a Z or W boson, where H...
We present the results of two measurements that combine the integrated luminosity of about 1.1 inverse attobarn collected by the B factory experiments BaBar and Belle in single physics analyses. The first measurement is a time-dependent $CP$ violation measurement of $B^{0} \to D^{(*)}_{CP} h^{0}$ decays, where $h^{0}$ denotes a light neutral hadron and the $D_{CP}$ meson decays into two-body...
A search for CP violation in the charm sector is performed through a full amplitude analysis of the decay mode $D^0 \rightarrow K^+ K^- \pi^+ \pi^-$. Its complicated resonant structure and the interferences between the various amplitudes together with the unprecedented statistic may offer the opportunity to observe CP violation for the first time in charm mesons. This symmetry breaking is...
Gauge theories play a fundamental role in physics, from high energy (e.g the Standard Model) to condensed matter (e.g. as effective low energy theories of many-body Hamiltonians).
Dimensional mismatch theories are a particular example of this. These models are characterized by gauge fields that live in an higher dimensions than the matter fields.
After an overview of the application of these...
We first sketch the concepts of the lattice regularisation in quantum field theory. This formulation provides a link to statistical mechanics, which enables its treatment by means of Monte Carlo simulations. They lead to non-perturbative numerical measurements of observables, such as the hadron spectrum, from first principle of Quantum Chromodynamics (QCD). We summarise the status of lattice...
In LHCb very rare decays are defined as decays that are forbidden in the Standard Model or with branching ratios smaller than 10-8. These include purely leptonic decays as Bs → µµ, Ks → µµ, Bs → ττ, which are loop decays very suppressed in the Standard Model but can be highly enhanced in new physics scenarios. Predictions for...
Purely baryonic decays of baryons such as $\Lambda_b \rightarrow p \bar{p} n$ and $\Lambda_b \rightarrow \Lambda p \bar{p}$, are predicted by the Standard Model but they have never been observed. Measurements of purely baryonic decays represent a valuable test of assumptions and factorization approach used in theoretical predictions. This contribution describes the first steps and the current...
Radiative $b$-hadron decays are a sensitive probe for new physics and a measurement of the photon polarisation in $b\rightarrow s \gamma$ transitions can help constrain several models of new physics. The methods used by the LHCb collaboration to measure the photon polarisation include the full amplitude analysis of $B \rightarrow K\pi\pi\gamma$ decays, the decay time analysis of $B_s...
The Compact Linear Collider (CLIC) is a mature option for a future electron-positron collider operating at centre-of-mass energies of up to 3 TeV. CLIC will be built and operated in a staged approach where we currently assume three centre-of-mass energy stages, at 380 GeV, 1.5 TeV and 3 TeV. This talk will summarize the status of the CLIC accelerator project, briefly describe the detector...
XENON1T is the world’s largest dual-phase xenon time-projection chamber, searching for dark matter via the nuclear recoils caused by interactions of weakly interacting massive particles (WIMPs) with xenon nucleons. Here a search for the inelastic WIMP-nucleus scattering is presented, whereby the interaction causes a transition to a low-lying excited nuclear state of either 129Xe or...
DARk matter WImp search with liquid xenoN (DARWIN) will be an experiment for direct detection of dark matter using a multi-ton time projection chamber filled with xenon at its core. As a detector searching for rare events, a extremely good understanding of the all possible backgrounds is required, as well as a detailed simulation of all of them to quantify /estimate the expected background...
Having completed the Standard Model but with several important questions still unanswered, the broadest search for leads towards new physics must be undertaken.
Starting from a very precise, high luminosity Z, W, Higgs and top e+e- factory, the Future Circular Colliders based on the CERN infrastructure of circular tunnels complemented with a 100 km ring passing under Lac Léman, will offer the...
The XENON1T experiment searches for Weakly Interacting Massive Particle (WIMP) dark matter candidate with a dual-phase xenon Time Projection Chamber (TPC) located at Laboratori Nazionali del Gran Sasso, Italy, under 3600 m.w.e. overburden. The detector, in operation since summer 2016, employs 3.3 tonnes of liquid xenon, 2 of which are used as target mass. The newest result from 278.8 days of...
One of the flagship projects of next-generation dark matter experiments will be DARWIN (DARk matter WImp search with liquid xenoN). With its 50 (40) tons of total (active) xenon target, DARWIN will be able to explore the entire experimentally accessible parameter space for WIMPs as dark matter candidates. Such a large detector, with its low-energy threshold and ultra low background level, will...
We present the status of the Canted-Cosine-Theta (CCT) design of an FCC-hh / HE-LHC dipole, its magnetic and mechanical properties, as well as its protectability. We will develop on the strengths and challenges of this design and lay out the R&D plan at Paul Scherrer Institute to address the challenges, together with first practical results.
The ArDM experiment is a tonne-scale liquid argon detector for direct WIMPs dark matter search which has been running in dual-phase mode since Dec. 2017. Out of its 1.5 tonne total liquid argon volume, 650 kg constitutes the active target of the dual-phase time projection chamber. The scintillation (S1) and ionization (S2) signals has been successfully detected. The detector response and...
The Canted-Cosine-Theta (CCT) type magnet has been proposed for Future Circular Collider (FCC) design. Its unique geometry lowers the coil stress intrinsically. Nevertheless, the former itself is also a barrier for heat to quickly propagate in case of a quench. To succeed in the magnet design and construction, further investigation is required on its electrothermal behavior. The potential...
The First G-APD Cherenkov Telescope (FACT) is performing unbiased monitoring of nearby bright TeV Blazars. Despite being among the best-studied objects, their TeV emission mechanisms and extreme variability are far from understood. Exploiting the excellent temporal coverage of FACT data, we are performing unprecedented long-term periodicity, variability and correlation studies essential to...
The Canted-Cosine-Theta (CCT) PSI magnet program aims at demonstrating that the CCT technology has the potential for the development of 16 T dipole magnets, required for the “near” future of circular colliders. The first step in this direction is the implementation of a Nb3Sn 1-m-long, 2-layer CCT single-aperture dipole model, referred to as Canted Dipole One (CD1) which is designed to achieve...
The First G-APD Cherenkov Telescope (FACT) monitors bright extragalactic gamma-ray sources.
Since summer 2012 it is operated from remote, and the need for human interaction has continuously been reduced to the point where FACT is now running fully robotic.
In case of any problem or scientifically interesting event, automatic phone calls are initiated. This results in hight duty cycle and fast...
Beam-beam effects are one of the major limitations in past and present hadron colliders. If not understood and well controlled they might result in important particle losses and transverse beam size blow up, with a direct impact on the accelerator performances and discovery potentials. We present in this work the studies of beam-beam effects for the Future Circular Hadron Colliders. We will...
The SST-1M project, a 4 m-diameter Davies Cotton telescope with 9 degrees FoV and a 1296 pixels SiPM camera, is designed to meet the requirements of the next generation of ground based gamma-ray observatory CTA in the energy range above 3 TeV.
In this work, a special emphasis will be given to the commissioning results of the SST-1M camera but also to the latest performance validation tests...
During their passages in the accelerator beam pipe, the charged particles induce electromagnetic wake fields that cause coherent oscillations of the beams. The excited coherent modes may lead to beam instabilities with a consequent limitation of the collider performances. The Landau damping, given by the diversification of oscillation frequencies of the particles in the beams, is a stabilizing...
The high energy cosmic radiation detection (HERD) facility is a space astronomy payload proposed to be installed onboard the future Chinese space station. The University of Geneva is working on the development of a tracking detector made of scintillating fibers read-out by arrays of silicon photomultipliers that could be placed on the four lateral sides of the detector. A mechanical and...
This study aims to use Machine Learning techniques to build models of the evolution of proton beam losses in the Large Hadron Collider for different operational scenarios. The models are trained on LHC 2017 operational data using a Random Forest supervised learning algorithm. From the models and covariance calculations we extract the parameters most contributing to the beam intensity...
The interaction of the proton bunches with its surrounding in the LHC can lead to the production of large amounts of free electrons in the beam pipe. These so-called electron clouds are able to induce coherent beam instabilities by interaction with the proton bunches, effectively limiting the maximal intensity of the beam. We extend a semi-analytical code for the beam transverse oscillation...
The IceCube detector has observed the first clear detection of a diffuse astrophysical high energy neutrino flux, and it is seeing evidence of the first point source, a flaring AGN. IceCube neutrino source searches involve looking for clustering of neutrinos or a strong correlation with known sources observed by other messengers which are also expected to emit a neutrino flux. The most recent...
During operation of the Large Hadron Collider (LHC) in 2017, unprecedentedly fast beam instabilities were observed. The instabilities are thought to have been the result of a complex sequence of events leading to a severe local vacuum degradation, resulting in the production of large amounts of free electrons and ions through beam-induced ionization. Simulation tools have been developed in...
T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment based in Japan. The off-axis muon neutrino beam with energy peaked at ~0.6 GeV is produced at the J-PARC facilities and directed towards the near detector at 280 meters and the far detector Super-Kamiokande at 295 kilometers. A precise knowledge of neutrino interactions is essential for an accurate estimation of the...
At the Paul Scherer Institute, we are developing a novel positive muon beam at low energy with high brightness by compressing the 6-dimensional phase space of a standard surface muon beam.
Muons are stopped in a helium gas target with a density gradient at cryogenic temperature and compressed by making use of complex-shaped B- and E-fields. Compression stages that act along two different...
The GERDA experiment searches for neutrinoless double beta decay of Ge76. The observation of this decay would imply that lepton number is violated in nature. Among the candidate isotopes for neutrinoless double decay, Ge76 is appealing due to its high intrinsic purity and excellent energy resolution. Thanks to the liquid argon veto system along with background discrimination techniques, GERDA...
Muonium, which is a bound state between an antimuon and an electron, is a promising tool to measure the gravitational interaction of antimatter and a second generation particle. To obtain a high muonium formation rate, a superfluid-helium (SFHe) thin film will be used as a target. As the first step to build the high brightness muonium beam, this talk presents the first experiment of muonium...
The Liquid Argon Time Projection Chamber (LAr TPC) is currently the most attractive technology for neutrino oscillation studies. Both single phase and dual phase LAr TPCs are now in the design and prototyping phase in the context of the Deep Underground Neutrino Experiment. The dual phase operation allows to amplify the charge signal, offering several advantages over the single phase.
The...
The Thin-TOF PET (TT-PET) project aims at the construction of a small-animal PET scanner based on silicon monolithic pixel sensors in SiGe BiCMOS technology with 30 ps time-of-flight resolution. The scanner will also measure the photon depth of interaction with 200 $\mu$m precision. This performance will lead to a significant improvement in the image resolution and signal-to-noise ratio with...
SHiP is a new general purpose fixed target facility. In its initial phase, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating $2\times10^{20}$ pot in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived...
The ultracold neutron (UCN) source at PSI converts fast neutrons from a spallation target into UCN via thermalization in D$_{2}$O, subsequent moderation in solid ortho-deuterium (sD$_{2}$), and finally down-scattering on the sD$_{2}$ lattice. However, during normal operation a decline in UCN output is observed. A conditioning process allows to recover the original performance, and in many...
Atomic parity violation experiments are one attempt to look for physics beyond the standard model. An experiment to measure the atomic parity violation electric dipole contribution to the energy transition 7S1/2 and 6D3/2 in singly ionised Radium-226 is currently ongoing. The extraction of the atomic parity violating signature for the measurement requires precise calculations based on...
The magnetic (Zemach) radius of the proton can be determined from the ground-state hyperfine splitting (HFS) of muonic hydrogen, an atom formed by a muon and a proton. At the Paul Scherrer Institute in Villigen, Switzerland, we aim to measure the HFS at the ppm level by means of laser spectroscopy.
Exciting this electric dipole forbidden transition, requires high laser fluence at an unusual...
CMS is a multi-purpose detector constructed to study high-energy particle collisions of the LHC at CERN. An all-silicon pixel tracker system provides CMS with excellent resolution for charged tracks and efficient tagging of b-jets. At the beginning of 2017, a new pixel detector has been installed anticipating the increase of instantaneous luminosity of the LHC to up to...
For operation at the High Luminosity LHC, the ATLAS detector will be upgraded in 2024-2026. Its Inner Tracker will be able to handle pile-up conditions of $\left<\mu\right>=200$ at a trigger rate of 1 MHz. This increases the digital data output to up to 5.12 Gbps per pixel module. The optical to electrical conversion stage, the optoboard, needs to be upgraded in order to cope with this...
The multi-dimensional energy correction for jets arising from bottom-quarks is presented. The study is performed on a simulated dataset of jets produced in 13 TeV proton-proton collisions. The energy correction is computed through a regression based on a deep neural network. The b-jet regression is trained on jet properties and jet composition information. The b-jet energy correction and jet...
At the High Luminosity LHC, the ATLAS trigger and data acquisition (TDAQ) system necessary to select in real-time interesting data will have to deal with severe reconstruction challenges due to due to the unprecedented rates of particle collisions. The Hardware-based Tracking for the Trigger (HTT) is a critical element to deal with these data-taking conditions. It implements track...
In 2017 the first evidence in CMS data of the Higgs boson (originally discovered in 2012 by ATLAS and CMS collaborations) decaying into a pair of b-bbar quarks has been observed with a significance of 3.3 sigma for associated Higgs production with a vector boson. This analysis is dominated by a large background of V+Jets events and therefore multivariate methods are used to classify signal and...
The two photon decay channel is among the most sensitive for Higgs physics at the LHC. In particular, it provides the best precision for the measurement of many Higgs boson properties. The ability to interpret LHC data in this channel relies on accurately modeling the detector response to prompt photons. Fine-tuning the particle detector simulation through the exploitation of clean standard...
The Minimal Supersymmetric Standard Model (MSSM) is today one of the most credited theories for physics Beyond the Standard Model (BSM). However, despite its success in providing a solution to many cosmological and High Energy Physics (HEP) observations, MSSM particles are still elusive today at the Large Hadron Collider (LHC). In this context, the zero lepton SUSY Multijets analysis has a...
Hadronic jets coming from the fragmentation of b-quarks are crucial tools for a number of physics channels at the CERN LHC, ranging from the Higgs physics to searches for physics beyond the Standard Model. We present a technique that allows tuning the simulated response of the CMS detector at the LHC to b-jets. Machine learning algorithms and likelihood fits are used to obtain finely-grained...
