A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on $6.8\times {10}^6$ positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to $\sim 250\mathrm{GeV}$, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

The LHCb experiment has been taking data at the Large Hadron Collider (LHC) at CERN since the end of 2009. One of its key detector components is the Ring-I

Neutrinoless double beta decay is a process that violates lepton number conservation. It is predicted to occur in extensions of the standard model of particle physics. This Letter reports the results from phase I of the Germanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope ${}^{76}\mathrm{Ge}$. Data considered in the present analysis have been collected between November 2011 and May 2013 with a total exposure of 21.6 kg yr. A blind analysis is performed. The background index is about $1\times {10}^{-2}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$ after pulse shape discrimination. No signal is observed and a lower limit is derived for the half-life of neutrinoless double beta decay of ${}^{76}\mathrm{Ge}$, $T_{1/2}^{0\nu }>2.1\times {10}^{25}\mathrm{yr}$ (90% C.L.). The combination with the results from the previous experiments with ${}^{76}\mathrm{Ge}$ yields $T_{1/2}^{0\nu }>3.0\times {10}^{25}\mathrm{yr}$ (90% C.L.).

The quantum numbers of the $X(3872)$ meson are determined to be $J^{PC}=1^{++}$ based on angular correlations in $B^{+}\to X(3872)K^{+}$ decays, where $X(3872)\to {\pi }^{+}{\pi }^{-}J/\psi$ and $J/\psi \to {\mu }^{+}{\mu }^{-}$. The data correspond to $1.0{\mathrm{fb}}^{-1}$ of $pp$ collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements $J^{PC}=2^{-+}$ is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the $X(3872)$ state.

A search for the rare decays $B_s^0\to {\mu }^{+}{\mu }^{-}$ and $B^0\to {\mu }^{+}{\mu }^{-}$ is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise $1.1{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=8\mathrm{TeV}$ and $1.0{\mathrm{fb}}^{-1}$ at $\sqrt{s}=7\mathrm{TeV}$. We observe an excess of $B_s^0\to {\mu }^{+}{\mu }^{-}$ candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is $5.3\times {10}^{-4}$ corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of $\mathcal{B}(B_s^0\to {\mu }^{+}{\mu }^{-})=({3.2}_{-1.2}^{+1.5})\times {10}^{-9}$, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of $B^0\to {\mu }^{+}{\mu }^{-}$ candidates is consistent with the background expectation, giving an upper limit of $\mathcal{B}(B^0\to {\mu }^{+}{\mu }^{-})<9.4\times {10}^{-10}$ at 95% confidence level.