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Publication

Measurement of J/psi polarization in pp collisions at root s=7 TeV

Abstract

An angular analysis of the decay J/psi ->mu (+) mu (-) is performed to measure the polarization of prompt J/psi mesons produced in pp collisions at . The dataset corresponds to an integrated luminosity of 0.37 fb(-1) collected with the LHCb detector. The measurement is presented as a function of transverse momentum, p (T), and rapidity, y, of the J/psi meson, in the kinematic region 2 < p (T)< 15 GeV/c and 2.0 < y < 4.5.

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Abstract

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Related concepts (32)

J/psi meson

The _J/psi (J/psi) meson ˈdʒeɪ_ˈsaɪ_ˈmiːzɒn is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as "charmonium" or psions. The _J/Psi is the most common form of charmonium, due to its spin of 1 and its low rest mass. The _J/Psi has a rest mass of 3.0969GeV/c2, just above that of the _charmed eta (2.9836GeV/c2), and a mean lifetime of 7.2e-21s.

Meson

In particle physics, a meson (ˈmiːzɒn,_ˈmɛzɒn) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, they have a meaningful physical size, a diameter of roughly one femtometre (10^−15 m), which is about 0.6 times the size of a proton or neutron. All mesons are unstable, with the longest-lived lasting for only a few tenths of a nanosecond.

Upsilon meson

The Upsilon meson (_Upsilon) is a quarkonium state (i.e. flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered because it is the lightest that can be produced without additional massive particles. It has a lifetime of 1.21e-20s and a mass about 9.46GeV/c2 in the ground state.

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Measurement of J/psi polarization in pp collisions at root s=7 TeV

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