Heat is transported through the outermost 30% of the Sun's interior by overturning convective motions. These motions are evident at the Sun's surface in the form of two characteristic cellular structures: granules and supergranules (~1000 and ~30,000 kilometers across, respectively). The existence of much larger cells has been suggested by both theory and observation for more than 45 years. We found evidence for giant cellular flows that persist for months by tracking the motions of supergranules. As expected from the effects of the Sun's rotation, the flows in these cells are clockwise around high pressure in the north and counterclockwise in the south and transport angular momentum toward the equator, maintaining the Sun's rapid equatorial rotation.

No abstract

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.

Search for supersymmetry in events with a τ lepton pair and missing transverse momentum in proton-proton collisions at √ s = 13 TeVThe CMS Collaboration * AbstractA search for the electroweak production of supersymmetric particles in proton-proton collisions at a center-of-mass energy of 13 TeV is presented in final states with a τ lepton pair. Both hadronic and leptonic decay modes are considered for the τ leptons. Scenarios involving the direct pair production of τ sleptons, or their indirect production via the decays of charginos and neutralinos, are investigated. The data correspond to an integrated luminosity of 35.9 fb −1 collected with the CMS detector in 2016. The observed number of events is consistent with the standard model background expectation. The results are interpreted as upper limits on the cross section for τ slepton pair production in different scenarios. The strongest limits are observed in the scenario of a purely left-handed low mass τ slepton decaying to a nearly massless neutralino. Exclusion limits are also set in the context of simplified models of chargino-neutralino and chargino pair production with decays to τ leptons, and range up to 710 and 630 GeV, respectively. Event reconstruction uses a particle-flow (PF) algorithm [50], combining information from the tracker, calorimeter, and muon systems to identify charged and neutral hadrons, photons, electrons, and muons in an event. The missing transverse momentum, p miss T , is computed as the −0.7 0.5 ± 0.1 ±0.2 2.1 ± 1.2 ±1.2 3.2 ± 1.2 ±1.4 6.2 ± 0.2 ±0.6 3.9 ± 0.2 ±0.6 <0.1 4 1j − 23 0.3 ± 0.3 +0.8 −0.3 <0.1 <0.1 0.4 ± 0.3 ±0.3 0.1 ± 0.0 +0.4 −0.1 0.9 ± 0.8 ±0.8 1.6 ± 0.9 ±1.2 1.8 ± 0.1 ±0.5 0.5 ± 0.1 ±0.4 <0.1 0 44 45 B The CMS Collaboration

Fixed-target experiments using primary electron beams can be powerful discovery tools for light dark matter in the sub-GeV mass range. The Light Dark Matter eXperiment (LDMX) is designed to measure missing momentum in high-rate electron fixed-target reactions with beam energies of 4 GeV to 16 GeV. A prerequisite for achieving several important sensitivity milestones is the capability to efficiently reject backgrounds associated with few-GeV bremsstrahlung, by twelve orders of magnitude, while maintaining high efficiency for signal. The primary challenge arises from events with photo-nuclear