Search

This paper presents the first results of the study of high-energy electron and muon neutrino charged-current interactions in the FASER$\nu$ emulsion/tungsten detector of the FASER experiment at the LHC. A subset of the FASER$\nu$ volume, which corresponds to a target mass of 128.6~kg, was exposed to neutrinos from the LHC $pp$ collisions with a centre-of-mass energy of 13.6~TeV and an integrated luminosity of 9.5 fb$^{-1}$. Applying stringent selections requiring electrons with reconstructed energy above 200~GeV, four electron neutrino interaction candidate events are observed with an expected background of $0.025^{+0.015}_{-0.010}$, leading to a statistical significance of 5.2$\sigma$. This is the first direct observation of electron neutrino interactions at a particle collider. Eight muon neutrino interaction candidate events are also detected, with an expected background of $0.22^{+0.09}_{-0.07}$, leading to a statistical significance of 5.7$\sigma$. The signal events include neutrinos with energies in the TeV range, the highest-energy electron and muon neutrinos ever detected from an artificial source. The energy-independent part of the interaction cross section per nucleon is measured over an energy range of 560--1740 GeV (520--1760 GeV) for $\nu_e$ ($\nu_{\mu}$) to be $(1.2_{-0.7}^{+0.8}) \times 10^{-38}~\mathrm{cm}^{2}\,\mathrm{GeV}^{-1}$ ($(0.5\pm0.2) \times 10^{-38}~\mathrm{cm}^{2}\,\mathrm{GeV}^{-1}$), consistent with Standard Model predictions. These are the first measurements of neutrino interaction cross sections in those energy ranges.

The Forward Search Experiment (FASER) at CERN's Large Hadron Collider (LHC) has recently directly detected the first collider neutrinos. Neutrinos play an important role in all FASER analyses, either as signal or background, and it is therefore essential to understand the neutrino event rates. In this study, we update previous simulations and present prescriptions for theoretical predictions of neutrino fluxes and cross sections, together with their associated uncertainties. With these results, we discuss the potential for possible measurements that could be carried out in the coming years with the FASER neutrino data to be collected in LHC Run 3 and Run 4., Comment: 19 pages, 10 figures

The effect of school closures on the spread of COVID-19 has been discussed among experts and the general public since those measures have been taken only a few months after the start of the pandemic in 2020. Within this study, the JuneGermany framework, is used to quantify the impact of school closures in the German state Rhineland Palatinate using an agent-based simulation approach. It was found that the simulations predicts a reduction of the number of infections, hospitalizations as well as death by a factor of 2.5 compared to scenarios, where no school closures are enforced, during the second wave between October 2020 and February 2021, Comment: 5 pages, 3 figures

During the COVID-19 pandemic, a large variance of incidence rates on local level, e.g. cities and districts, within one country has been observed, while the same non-pharmaceutical measures have been taken to control the spread of the virus. This variance in incidence rates triggered the question, if the spread of incidence rates can be explained only by statistical processes and the local population statistics or if indeed other factors, e.g. local information campaigns, have to be considered. Within this paper we study the expected spread of incidence rates in the German State of Rhineland Palatinate during the second COVID-19 wave using an agent based simulation and find that the spread of incidence rates can be solely explained by population statistics and further statical effects., Comment: 5 Pages, 3 Figures

The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Specifically, discussions focus on cavities with relatively small volumes, which are currently employed in the search for axions. In this context, we propose a novel experimental scheme that enables the detection of gravitational waves in the GHz regime, which could originate, for example, from primordial black hole mergers. The scheme is based on synchronous measurements of cavity signals from multiple devices operating in magnetic fields at distant locations. While gravitational wave signatures might be detectable in individual cavities, distinguishing them from noise is highly challenging. By analyzing the correlation among signals from several, possibly geographically separated cavities, it is not only possible to significantly enhance the signal-to-noise ratio but also to investigate the source of those gravitational wave signatures. In the context of this proposal, a first demonstration experiment with one superconducting cavity is currently conducted, which is the basis of the proposed data-analysis approaches. On this basis the prospects of GravNet (Global Network of Cavities to Search for Gravitational Waves) are outlined in the paper., Comment: 9 pages

We show the first results of a new cavity based haloscope searching for dark photons with masses around $34~\mu\text{eV}$. Dark photons are hypothetical vector particles and a compelling dark matter candidate. Having the same quantum numbers as photons a kinematic mixing between both is expected, leading to conversions from dark photons to standard model photons, where the photon frequency depends on the dark photon mass. For wavelengths in the microwave regime resonators are typically used to enhance the signal. A new experiment is setup at the University of Mainz. In this paper we present the initial results from the new setup searching for dark photons utilising a 8.3 GHz copper cavity at LHe temperatures. Limits on the kinetic mixing parameter $\chi < (6.20 \pm 3.15^\text{(exp.)} \pm 9.65^\text{(SG)}) \cdot 10^{-14}$ at 95\% CL are set at a single frequency as proof of concept. Finally the next steps of the experiment and expected sensitivity are detailed., Comment: 6 pages

Axions and axion-like particles are hypothetical particles predicted in extensions of the standard model and are promising cold dark matter candidates. The Any Light Particle Search (ALPS II) experiment is a light-shining-through-the-wall experiment that aims to produce these particles from a strong light source and magnetic field and subsequently detect them through a reconversion into photons. With an expected rate $\sim$ 1 photon per day, a sensitive detection scheme needs to be employed and characterized. One foreseen detector is based on a transition edge sensor (TES). Here, we investigate machine and deep learning algorithms for the rejection of background events recorded with the TES. We also present a first application of convolutional neural networks to classify time series data measured with the TES., Comment: 11 pages, 5 figures, accepted for publication in Annals of Physics. Contribution to the Patras 2022 Workshop on Axions, WIMPs, and WISPs

We report the first direct observation of neutrino interactions at a particle collider experiment. Neutrino candidate events are identified in a 13.6 TeV center-of-mass energy $pp$ collision data set of 35.4 fb${}^{-1}$ using the active electronic components of the FASER detector at the Large Hadron Collider. The candidates are required to have a track propagating through the entire length of the FASER detector and be consistent with a muon neutrino charged-current interaction. We infer $153^{+12}_{-13}$ neutrino interactions with a significance of 16 standard deviations above the background-only hypothesis. These events are consistent with the characteristics expected from neutrino interactions in terms of secondary particle production and spatial distribution, and they imply the observation of both neutrinos and anti-neutrinos with an incident neutrino energy of significantly above 200 GeV., Comment: Submitted to PRL on March 24 2023

The June software package is an open-source framework for the detailed simulation of epidemics based on social interactions in a virtual population reflecting age, gender, ethnicity, and socio-economic indicators in England. In this paper, we present a new version of the framework specifically adapted for Germany, which allows the simulation of the entire German population using publicly available information on households, schools, universities, workplaces, and mobility data for Germany. Moreover, JuneGermany incorporates testing and vaccination strategies within the population as well as the simultaneous handling of several different virus strains. First validation tests of the framework have been performed for the state of Rhineland Palatinate based on data collected between October 2020 and December 2020 and then extrapolated to March 2021, i.e. the end of the second wave., Comment: 10 pages, 11 figures

The future Large Hadron Electron Collider (LHeC) would enable collisions of an intense electron beam with either protons or heavy ions at the High Luminosity-Large Hadron Collider (HL- LHC). With a center of mass energy greater than a TeV and a high luminosity, the LHeC would be a new-generation collider for deep-inelastic scattering (DIS) and a significant facility for precise Higgs physics, complementing pp and electron-positron colliders. Anomalous hadronic decay signatures of the Higgs Boson, such as those into three or more partons, are challenging to detect at the LHC due to high background rates, but they may be observable at the LHeC. This paper presents the expected sensitivity of the LHeC for the decay channels $H \rightarrow 3jets$ and $H \rightarrow 4jets$, assuming an integrated luminosity of 1 ab$^{-1}$. Our analysis indicates that upper limits on the branching ratio of the Higgs Boson of 0.35 and 0.17 at 95% confidence limit for these processes are possible., Comment: 8 pages

The LHC newly-discovered resonant structures around 7 GeV, such as the $X(6900)$, could be responsible for the observed excess in light-by-light scattering between 5 and 10 GeV. We show that the ATLAS data for light-by-light scattering may indeed be explained by such a state with the $\gamma \gamma$ branching ratio of order of $10^{-4}$. This is much larger than the value inferred by the vector-meson dominance, but agrees quite well with the tetraquark expectation for the nature of this state. Further light-by-light scattering data in this region, obtained during the ongoing Run-3 and future Run-4 of the LHC, are required to pin down these states in $\gamma\gamma$ channel., Comment: 5 pages, 2 figures, to appear in the proceedings of the XVth Quark confinement and the Hadron spectrum conference, August 1st - 6th, 2022, Stavanger, Norway

Several experiments have been proposed in the recent years to study the nature of tau neutrinos, in particular aiming for a first observation of tau anti-neutrinos, more stringent upper limit on its anomalous magnetic moment as well as new constrains on the strange-quark content of the nucleon. We propose here a new low-cost neutrino experiment at the CERN North area, named NaNu (North Area NeUtrino), compatible with the realization of the future SHADOWS and HIKE experiments at the same experimental area., Comment: 7 pages, 6 figures

The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Most concepts foresee moderate magnetic fields in rather small volumes, similar to those which are currently employed for axion-like particle searches. We propose to use the magnet system of the Compact Muon Solenoid (CMS) experiment after the high luminosity phase of the LHC as a key component for a future detector for gravitational waves in the MHz frequency range. In this paper we briefly discuss a possible cavity concept which can be integrated into CMS and additionally provide a first estimation of its possible sensitivity., Comment: 4 pages, 2 figures

The LHCb Collaboration has recently discovered a structure around 6.9 GeV in the double-$J/\psi$ mass distribution, possibly a first fully-charmed tetraquark state $X(6900)$. Based on vector-meson dominance (VMD) such a state should have a significant branching ratio for decaying into two photons. We show that the recorded LHC data for the light-by-light scattering may indeed accommodate for such a state, with a $\gamma \gamma$ branching ratio of order of $10^{-4}$, which is larger even than the value inferred by the VMD. The spin-parity assignment $0^{-+}$ is in better agreement with the VMD prediction than $0^{++}$, albeit not significantly at the current precision. Further light-by-light scattering data in this region, clarifying the nature of this state, should be obtained in the Run 3 and probably in the high-luminosity phase of the LHC (Run 4 etc.)., Comment: 6 pages, 4 figures

FASER, the ForwArd Search ExpeRiment, is an experiment dedicated to searching for light, extremely weakly-interacting particles at CERN's Large Hadron Collider (LHC). Such particles may be produced in the very forward direction of the LHC's high-energy collisions and then decay to visible particles inside the FASER detector, which is placed 480 m downstream of the ATLAS interaction point, aligned with the beam collisions axis. FASER also includes a sub-detector, FASER$\nu$, designed to detect neutrinos produced in the LHC collisions and to study their properties. In this paper, each component of the FASER detector is described in detail, as well as the installation of the experiment system and its commissioning using cosmic-rays collected in September 2021 and during the LHC pilot beam test carried out in October 2021. FASER will start taking LHC collision data in 2022, and will run throughout LHC Run 3., Comment: 92 pages, 72 Figures

The strong-coupling constant is determined from the low-momentum region of the transverse-momentum distribution of $Z$ bosons produced through the Drell-Yan process, using predictions at third order in perturbative QCD. The analysis employs a measurement performed in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 1.96$ TeV with the CDF experiment. The determined value of the strong coupling at the reference scale corresponding to the $Z$-boson mass is $\alpha_S(m_Z) = 0.1191^{+0.0013}_{-0.0016}$., Comment: Included O($\alpha_S^3$) matching, simultaneous fit of PDFs and $\alpha_S$, and additional uncertainties related to QED, non perturbative effects, and matching to fixed order. Version published by EPJC

The future Large Hadron electron Collider (LHeC) would allow collisions of an intense electron beam with protons or heavy ions at the High Luminosity-Large Hadron Collider (HL-LHC). Owing to a center of mass energy greater than a TeV and very high luminosity (~1 ab{-1}), the LHeC would not only be a new generation collider for deep-inelastic scattering (DIS) but also an important facility for precision Higgs physics, complementary to pp and e+ e- colliders. Previously, it has been found that uncertainties of 0.8% and 7.4% can be achieved on the Higgs boson coupling strength to b- and c-quarks respectively. These results were obtained in the fast simulation frameworks for the LHeC detector. Focusing on the dominant Higgs boson decay channel, H to bb, the present work aims to give a comparison of these results with a fully simulated detector. We present our results in this study using the publicly available ATLAS software infrastructure. Based on state-of-the art reconstruction algorithms, a novel analysis of the bb decay could be performed leading to an independent verification of the existing results to an exceptionally high precision., Comment: 9 pages, 11 figures

FASER is a new experiment designed to search for new light weakly-interacting long-lived particles (LLPs) and study high-energy neutrino interactions in the very forward region of the LHC collisions at CERN. The experimental apparatus is situated 480 m downstream of the ATLAS interaction-point aligned with the beam collision axis. The FASER detector includes four identical tracker stations constructed from silicon microstrip detectors. Three of the tracker stations form a tracking spectrometer, and enable FASER to detect the decay products of LLPs decaying inside the apparatus, whereas the fourth station is used for the neutrino analysis. The spectrometer has been installed in the LHC complex since March 2021, while the fourth station is not yet installed. FASER will start physics data taking when the LHC resumes operation in early 2022. This paper describes the design, construction and testing of the tracking spectrometer, including the associated components such as the mechanics, readout electronics, power supplies and cooling system.

The search for weakly interacting, light particles that couple to photons received significant attention in recent years. When those particles are produced at high energies, they lead to two, nearly collinear photons after their decay and hence can be detected by an electromagnetic calorimeter system. The typical dominant background in searches for those high energetic weakly particles are single, high energetic photons, which leave similar signatures in a standard calorimeter system. One promising approach to separate signal from background events is to employ a dedicated pre-shower detector in front of the calorimeter that can distinguish one- and two-photon signatures. In this work we present a conceptual design of such detector which is able to separate one from two collinear photon signatures with efficiencies between 20% to 80% for two photons separated by 0.1mm to 2mm, respectively, with energies above 300 GeV and a background rejection of more than 90%. Our pre-shower detector design has an active surface area of 10cm x 10cm, a depth of 230mm and is based on Micromegas detectors, thus offering a cost effective solution., Comment: 8 pages, 6 figures

The FASER experiment is a new small and inexpensive experiment that is placed 480 meters downstream of the ATLAS experiment at the CERN LHC. FASER is designed to capture decays of new long-lived particles, produced outside of the ATLAS detector acceptance. These rare particles can decay in the FASER detector together with about 500-1000 Hz of other particles originating from the ATLAS interaction point. A very high efficiency trigger and data acquisition system is required to ensure that the physics events of interest will be recorded. This paper describes the trigger and data acquisition system of the FASER experiment and presents performance results of the system acquired during initial commissioning.

The application of cryogenic single photon detectors has found great use in high precision particle physics experiments such as ALPS (Any Light Particle Search) II, which implements it for fundamental studies to search for new particles. ALPS II is a light-shining-through-a-wall experiment searching for axion-like-particles, which couple to photons. The extremely low rate of photons generated by the conversion of such axion-like-particles necessitates a detector setup capable of low energy (~ 1 eV; as dictated by cavity optics) single photon detection with high efficiency and an ultra-low background level, with long-term stability. This can be realised by a Transition Edge Sensor (TES) setup with low-temperature SQUID readout., Comment: Proceedings contribution to EPS-HEP 2021, submitted to Proceedings of Science

We discuss the sensitivity of the $\gamma\gamma \to \tau^+\tau^-$ process in ultraperipheral Pb+Pb collisions at LHC energies on the anomalous magnetic moment of $\tau$ lepton ($a_\tau$). We derive the corresponding cross sections considering semi-leptonic decays of both leptons in the fiducial volume of ATLAS and CMS detectors. The expected limits on $a_\tau$ with the existing Pb+Pb dataset are found to be better by a factor of two comparing to current best experimental limits and can be further improved by another factor of two at High Luminosity LHC. In addition, our results for tau lepton electric dipole moment, $d_\tau$, can be competitive with the current best limits that were obtained by the Belle experiment., Comment: Submission to SciPost, XXVIII International Workshop on Deep-Inelastic Scattering and Related Subjects, 12-16 April 2021, presented by Mariola Klusek-Gawenda

Particle production from secondary proton-proton collisions, commonly referred to as pile-up, impair the sensitivity of both new physics searches and precision measurements at LHC experiments. We propose a novel algorithm, PUMA, for identifying pile-up objects with the help of deep neural networks based on sparse transformers. These attention mechanisms were developed for natural language processing but have become popular in other applications. In a realistic detector simulation, our method outperforms classical benchmark algorithms for pile-up mitigation in key observables. It provides a perspective for mitigating the effects of pile-up in the high luminosity era of the LHC, where up to 200 proton-proton collisions are expected to occur simultaneously., Comment: 17 pages, 6 figures, final published version