LHCb unveils new particles July 5, 2016 Please Register or Log in to view the hidden image! A view of the LHCb experimental cavern. Credit: Claudia Marcelloni/CERN On 28 June, the LHCb collaboration reported the observation of three new "exotic" particles and the confirmation of the existence of a fourth one in data from the Large Hadron Collider (LHC). These particles seem to be formed by four quarks (the fundamental constituent of the matter inside all the atoms of the universe): two quarks and two antiquarks (that is, a tetraquark). Due to their non-standard quark content, the newly observed particles have been included in the broad category of so-called exotic particles, although their exact theoretical interpretation is still under study. Please Register or Log in to view the hidden image! The image shows the data (black dots) of the mass distribution resulting from the association of the J/ψ and φ mesons, where the contribution of the four exotic particles is put into evidence by the four peaking structures at the bottom. Credit: CERN Read more at: http://phys.org/news/2016-07-lhcb-unveils-particles.html#jCp
http://arxiv.org/pdf/1606.07898v1.pdf EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) Amplitude analysis of B+ → J/ψφK+ decays Abstract The first full amplitude analysis of B+ → J/ψφK+ with J/ψ → µ +µ −, φ → K+K− decays is performed with a data sample of 3 fb−1 of pp collision data collected at √ s = 7 and 8 TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into φK+, and four J/ψφ structures are observed, each with significance over 5 standard deviations. The quantum numbers of these structures are determined with significance of at least 4 standard deviations. The lightest is best described as a D± s D∗∓ s cusp, but a resonant interpretation is also possible with mass consistent with, but width much larger than, previous measurements of the claimed X(4140) state. The model includes significant contributions from a number of expected kaon excitations, including the first observation of the K∗ (1680)+ → φK+ transition.
http://phys.org/news/2016-07-lhc-highs.html It's full speed ahead for the Large Hadron Collider (LHC), as it shatters its own records one after the other, achieving record luminosity, record numbers of bunches and a record beam lifespan. Some 2076 bunches of 120 billion protons are currently circulating in the ring in each direction. At the end of June, beams were maintained in the accelerator for a record 37 consecutive hours! But the main indicator of success for the operators is luminosity, the measurement of the number of potential collisions in a given time period. On 29 June, peak luminosity (the number of potential collisions per second and per surface unit) exceeded 1034cm-2s-1. This number may not mean much to most of us, but it made the LHC operators very proud as it corresponds to the ultimate objective defined by those who originally designed this huge machine! Read more at: http://phys.org/news/2016-07-lhc-highs.html#jCp
