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A wide range of physical and biological systems, including colloidal magnets, granular spinners, and starfish embryos, are characterized by strongly rotating units that give rise to odd viscosity and odd elasticity. These active systems can be described using a coarse-grained model in which the pairwise forces between particles include a transverse component compared to standard interactions due to a central potential. These non-potential, additional forces, referred to as odd interactions, do not conserve energy or angular momentum and induce rotational motion. Here, we study a two-dimensional crystal composed of inertial Brownian particles that interact via odd forces and are in thermal contact with their environment. We discover that, in the underdamped regime, the energy injected by odd forces can counteract dissipation due to friction, leading to quasi-dissipation-free excitations with finite frequency and wavelength. In the resulting non-equilibrium steady state, the system exhibits angular momentum and velocity correlations. When the strength of the odd forces exceeds a certain threshold or friction is too low, we show that a chiral active crystal with only harmonic springs becomes linearly unstable due to transverse fluctuations. This instability can be mitigated by introducing nonlinear central interactions, which suppress the divergence of short-wavelength velocity fluctuations and allows us to numerically explore the linearly unstable regime. This is characterized by pronounced temporal oscillations in the velocity featuring the existence of vortex structures and kinetic temperature values larger than the thermal temperature.

We propose a new experiment to measure the running of the electromagnetic coupling constant in the space-like region by scattering high-energy muons on atomic electrons of a low- Z target through the elastic process μ e → μ e . The differential cross section of this process, measured as a function of the squared momentum transfer t = q 2 < 0 , provides direct sensitivity to the leading-order hadronic contribution to the muon anomaly a μ HLO . By using a muon beam of 150 GeV, with an average rate of ∼ 1.3 × 10 7 muon/s, currently available at the CERN North Area, a statistical uncertainty of ∼ 0.3% can be achieved on a μ HLO after two years of data taking. The direct measurement of a μ HLO via μ e scattering will provide an independent determination, competitive with the time-like dispersive approach, and consolidate the theoretical prediction for the muon g -2 in the Standard Model. It will allow therefore a firmer interpretation of the measurements of the future muon g -2 experiments at Fermilab and J-PARC.

We propose a new experiment to measure the running of the electromagnetic coupling constant in the space-like region by scattering high-energy muons on atomic electrons of a low-Z target through the elastic process [Formula omitted]. The differential cross section of this process, measured as a function of the squared momentum transfer [Formula omitted], provides direct sensitivity to the leading-order hadronic contribution to the muon anomaly [Formula omitted]. By using a muon beam of 150 GeV, with an average rate of [Formula omitted]1.3 [Formula omitted] muon/s, currently available at the CERN North Area, a statistical uncertainty of [Formula omitted]0.3% can be achieved on [Formula omitted] after two years of data taking. The direct measurement of [Formula omitted] via [Formula omitted] scattering will provide an independent determination, competitive with the time-like dispersive approach, and consolidate the theoretical prediction for the muon g-2 in the Standard Model. It will allow therefore a firmer interpretation of the measurements of the future muon g-2 experiments at Fermilab and J-PARC.

The LHCb experiment will undergo a major upgrade during the second long shutdown (2019 - 2020). The upgrade will concern both the detector and the Data Acquisition system, which are to be rebuilt in order to optimally exploit the foreseen higher event rate. The Event Builder is the key component of the DAQ system, for it gathers data from the sub-detectors and builds up the whole event. The Event Builder network has to manage an incoming data rate of 32 Tb/s from a 40 MHz bunch-crossing frequency, with a cardinality of about 500 nodes. In this contribution we present an Event Builder implementation based on the InfiniBand network technology. This software relies on the InfiniBand verbs, which offers a user space interface to employ the Remote Direct Memory Access capabilities provided by the InfiniBand network devices. We will present the performance of the software on a cluster connected with 100 Gb/s InfiniBand network.

The LHCb experiment at CERN has decided to optimise its physics reach by removing the first level hardware trigger for 2020 and beyond. In addition to requiring fully redesigned front-end electronics this design creates interesting challenges for the data-acquisition and the rest of the online computing system. Such a system can only be realized within realistic cost using as much off-the-shelf hardware as possible. Relevant technologies evolve very quickly and thus the system design is architecture-centred and tries to avoid to depend too much on specific technologies. In this paper we describe the design, the motivations for various choices and the current favoured options for the implementation, and the status of the R&D. We will cover the back-end readout, which contains the only custom-made component, the event-building, the event-filter infrastructure, and storage.

The architecture of the data acquisition system foreseen for the LHCb upgrade, to be installed by 2018, is devised to readout events trigger-less, synchronously with the LHC bunch crossing rate at 40 MHz. Within this approach the readout boards act as a bridge between the front-end electronics and the High Level Trigger (HLT) computing farm. The baseline design for the LHCb readout is an ATCA board requiring dedicated crates. A local area standard network protocol is implemented in the on-board FPGAs to read out the data. The alternative solution proposed here consists in building the readout boards as PCIe peripherals of the event-builder servers. The main architectural advantage is that protocol and link-technology of the event-builder can be left open until very late, to profit from the most cost-effective industry technology available at the time of the LHC LS2.

In this numerical study we simulate burning propagation when the limiting transport mechanisms is the diffusion of oxygen and heat. This situation may be representative of smouldering combustion in the forest ground, when the intricate vegetation structure prevents the onset of large scale convection. The interplay between the diffusion processes results in a dynamical instability with a tendency of the burning front to develop cellular or dendritic patterns. The length scale associated with the observed patterns results to be a combination of the diffusion lengths associated with the two competing processes.

In this paper we present a method to calculate Casimir Forces for non equilibrium systems with long range correlations. The origin of the force are the fluctuating fields, and the modification that the external, macroscopic objects induce in the spectrum of the fluctuations. The method is first illustrated with a simple model: a reaction-diffusion non-equilibrium system with an structure factor that possesses a characteristic length. The second part of the paper deals with a granular fluid where correlations are long ranged at all scales. In the first case the hydrodynamic fluctuations are confined by two plates, while in the second one the confinement comes from two immobile large and heavy particles. In both cases Casimir forces are calculated, and their properties analyzed. [PUBLICATION ABSTRACT]

Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb −1 , collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) resonance, is observed in the decay modes$$ \\mathrm{X}(3842)\\to {D}^0{\\overline{D}}^0 $$X 3842 → D 0 D ¯ 0 and X(3842) → D + D − . The mass and the natural width of this state are measured to be$$ \\begin{array}{l}{m}_{X(3842)}=3842.71\\pm 0.16\\pm 0.12\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{X(3842)}=2.79\\pm 0.51\\pm 0.35\\ MeV,\\hfill \\end{array} $$m X 3842 = 3842.71 ± 0.16 ± 0.12 M e V / c 2 , Γ X 3842 = 2.79 ± 0.51 ± 0.35 M e V , where the first uncertainty is statistical and the second is systematic. The observed mass and narrow natural width suggest the interpretation of the new state as the unobserved (spin-3 ψ 3 1 3 D 3 ) charmonium state. In addition, prompt hadroproduction of the ψ (3770) and χ 2 (3930) states is observed for the first time, and the parameters of these states are measured to be$$ \\begin{array}{l}{m}_{\\psi (3770)}=3778.1\\pm 0.7\\pm 0.6\\ MeV/{c}^2,\\hfill \\\ {}{m}_{\\chi_2(3930)}=3921.9\\pm 0.6\\pm 0.2\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{\\chi_2(3930)}=36.6 \\pm 1.9 \\pm 0.9\\ MeV,\\hfill \\end{array} $$m ψ 3770 = 3778.1 ± 0.7 ± 0.6 M e V / c 2 , m χ 2 3930 = 3921.9 ± 0.6 ± 0.2 M e V / c 2 , Γ χ 2 3930 = 36.6 ± 1.9 ± 0.9 M e V , where the first uncertainty is statistical and the second is systematic.