6533b7dcfe1ef96bd12733cd

RESEARCH PRODUCT

Measurement of the chi(b) (3 P) mass and of the relative rate of chi(b1) (1 P) and chi(b2) (1 P) production

subject

description

The production of $\chi_b$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $\sqrt{s}=7$ and $8$ TeV and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $\chi_b$ mesons are identified through their decays to $\Upsilon(1S)\gamma$ and $\Upsilon(2S)\gamma$ using photons that converted to $e^+e^-$ pairs in the detector. The $\chi_b(3P)$ meson mass, and the relative prompt production rate of $\chi_{b1}(1P)$ and $\chi_{b2}(1P)$ mesons as a function of the $\Upsilon(1S)$ transverse momentum in the $\chi_b$ rapidity range 2.0< $y$<4.5, are measured. Assuming a mass splitting between the $\chi_{b1}(3P)$ and the $\chi_{b2}(3P)$ states of 10.5 MeV/$c^2$, the mass of the $\chi_{b1}(3P)$ meson is \begin{equation*} m(\chi_{b1}(3P))= 10515.7^{+2.2}_{-3.9}(stat) ^{+1.5}_{-2.1}(syst) MeV/c^2. \end{equation*} The production of χ$_{b}$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $ \sqrt{s} $ =7 and 8 TeV and corresponding to an integrated luminosity of 3.0 fb$^{−1}$. The χ$_{b}$ mesons are identified through their decays to ϒ(1S)γ and ϒ(2S)γ using photons that converted to e$^{+}$ e$^{−}$ pairs in the detector. The relative prompt production rate of χ$_{b1}$(1P) and χ$_{b2}$(1P) mesons is measured as a function of the ϒ(1S) transverse momentum in the χ$_{b}$ rapidity range 2.0 < y <4.5. A precise measurement of the χ$_{b}$ (3P) mass is also performed. Assuming a mass splitting between the χ$_{b1}$(3P) and the χ$_{b2}$(3P) states of 10.5 MeV/c$^{2}$, the measured mass of the χ$_{b1}$(3P) meson is The production of $\chi_b$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $\sqrt{s}=7$ and $8$ TeV and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $\chi_b$ mesons are identified through their decays to $\Upsilon(1S)\gamma$ and $\Upsilon(2S)\gamma$ using photons that converted to $e^+e^-$ pairs in the detector. The relative prompt production rate of $\chi_{b1}(1P)$ and $\chi_{b2}(1P)$ mesons is measured as a function of the $\Upsilon(1S)$ transverse momentum in the $\chi_b$ rapidity range $2.0<y<4.5$. A precise measurement of the $\chi_b(3P)$ mass is also performed. Assuming a mass splitting between the $\chi_{b1}(3P)$ and the $\chi_{b2}(3P)$ states of 10.5 MeV/$c^2$, the measured mass of the $\chi_{b1}(3P)$ meson is $ m(\chi_{b1}(3P))= 10515.7^{+2.2}_{-3.9}(stat) ^{+1.5}_{-2.1}(syst) MeV/c^2.$