53 documents found, page 1 of 6
The SHiP experiment at the proposed CERN SPS Beam Dump Facility
Ahdida, C.; Akmete, A.; Albanese, R.; Alt, J.; Alexandrov, A.; Anokhina, A.; Aoki, S.; Arduini, G.; Atkin, E.; Azorskiy, N.; Back, J. J.; Bagulya, A.
Sensitivity of the SHiP experiment to light dark matter
Ahdida, C.; Akmete, A.; Albanese, R.; Alexandrov, A.; Anokhina, A.; Aoki, S.; Arduini, G.; Atkin, E.; Azorskiy, N.; Back, J. J.; Bagulya, A.Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopt...
New analysis of $\eta\pi$ tensor resonances measured at the COMPASS experiment
JPAC, COMPASS collaboration (235 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.We present a new amplitude analysis of the $\eta\pi$ $D$-wave in $\pi^- p\to \eta\pi^- p$ measured by COMPASS. Employing an analytical model based on the principles of the relativistic $S$-matrix, we find two resonances that can be identified with the $a_2(1320)$ and the excited $a_2^\prime(1700)$, and perform a comprehensive analysis of their pole positions. For the mass and width of the $a_2$ we find $M=(1307...
Light isovector resonances in $\pi^- p \to \pi^-\pi^-\pi^+ p$ at 190 GeV/${\it c}$
COMPASS collaboration (226 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.We have performed the most comprehensive resonance-model fit of π-π-π+ states using the results of our previously published partial-wave analysis (PWA) of a large data set of diffractive-dissociation events from the reaction π-+p→π-π-π++precoil with a 190 GeV/c pion beam. The PWA results, which were obtained in 100 bins of three-pion mass, 0.5<m3π<2.5 GeV/c2, and simultaneously in 11 bins of the reduced four-...
Search for muoproduction of $X (3872)$ at COMPASS and indication of a new state...
COMPASS collaboration (228 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.We have observed exclusive production of the exotic $X(3872)$ hadron in the reaction $\mu^+~N \rightarrow \mu^+ (J\!/\!\psi\pi^+\pi^-)\pi^{\pm}~N'$ using COMPASS data collected with incoming muons of 160~GeV/$c$ and 200~GeV/$c$ momentum. The statistical significance of the $X(3872)$ signal is 6$\sigma$. The shape of the two-pion mass distribution shows disagreement with previous observations. The product of cro...
Longitudinal double-spin asymmetry $A_1^{\rm p}$ and spin-dependent structure f...
COMPASS collaboration (226 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.We present a precise measurement of the proton longitudinal double-spin asymmetry A1p and the proton spin-dependent structure function g1p at photon virtualities 0.006(GeV/c)2<Q2<1(GeV/c)2 in the Bjorken x range of 4×10−5<x<4×10−2 . The results are based on data collected by the COMPASS Collaboration at CERN using muon beam energies of 160GeV and 200GeV . The statistical precision is more than tenfold better th...
Centrality determination of Au + Au collisions at 1.23A GeV with HADES
HADES collaboration (113 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Ramos, S.; Silva, L.The centrality determination for Au+Au collisions at 1.23A GeV, as measured with HADES at the GSI-SIS18, is described. In order to extract collision geometry related quantities, such as the average impact parameter or number of participating nucleons, a Glauber Monte Carlo approach is employed. For the application of this model to collisions at this relatively low centre-of-mass energy of $\sqrt{s_{\mathrm{NN}}...
Deep sub-threshold $\phi$ production in Au+Au collisions
HADES collaboration (114 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Ramos, S.; Silva, L.We present data on charged kaons (K+-) and {\phi} mesons in Au(1.23A GeV)+Au collisions. It is the first simultaneous measurement of K and {\phi} mesons in central heavy-ion collisions below a kinetic beam energy of 10A GeV. The {\phi}/K- multiplicity ratio is found to be surprisingly high with a value of 0.52 +- 0.16 and shows no dependence on the centrality of the collision. Consequently, the different slopes...
Transverse-momentum-dependent Multiplicities of Charged Hadrons in Muon-Deutero...
COMPASS collaboration (226 authors); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality Q2>1 (GeV/c)2, invariant mass of the hadronic system W>5 GeV/c2, Bjorken scaling variable in the range 0.003<x<0.4, fraction of the virtual photon...
$\Sigma^0$ production in proton nucleus collisions near threshold
HADES collaboration (109 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Ramos, S.; Silva, L.The production of Σ0 baryons in the nuclear reaction p (3.5 GeV) + Nb (corresponding to sNN=3.18 GeV) is studied with the detector set-up HADES at GSI, Darmstadt. Σ0 s were identified via the decay Σ0→Λγ with subsequent decays Λ→pπ− in coincidence with a e+e− pair from either external ( γ→e+e− ) or internal (Dalitz decay γ⁎→e+e− ) gamma conversions. The differential Σ0 cross section integrated over the detector...