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A few-body type computation is performed for a three-charge-particle collision with participation of a slow antiproton rm{p} and a muonic muonium atom (true muonium), i.e. a bound state of two muons (\\mu+}\\mu-}) in its ground state. The total cross section of the following reaction \\rm p}+(\\mu+}\\mu-}) \\rightarrow \\bar{\\rm{H}}_{\\mu} + \\mu-}, where muonic anti-hydrogen \\rm{H}}_{\\mu}=(\\bar{\\rm p}\\mu+})} is a bound state of an antiproton and positive muon, is computed in the framework of a set of coupled two-component Faddeev-Hahn-type equation. A better known negative muon transfer low energy three-body reaction: \\rm t}+} + ({\\rm d}+}\\mu-})\\rightarrow ({\\rm t}+}\\mu-}) + {\\rm d}+} is also computed as a test system. Here, t super(+) is triton and d super(+) is deuterium.

Antiproton production in cosmic-ray and accelerator environments is a critical input for indirect dark-matter searches and for probing beyond–Standard Model physics. Existing “classic” parameterizations, while widely used, suffer from inconsistencies with energy–momentum conservation and require piecewise formulas to cover different kinematic regions, often underestimating the overall production rate. We introduce a unified parameterization based on modeling the collision as p+xp→p¯+X (x>1) where the effective multiplicity factor x encapsulates multi–nucleon interactions in the target system. This approach naturally enforces kinematic constraints, yields a continuous description across the full angular range, and eliminates the need for ad hoc switching between formulas.

Using proton-antiproton collision data corresponding to an integrated luminosity of 8.8 fb -1 collected in Tevatron Run 2, CDF performed a high precision measurement of the W mass. This result, 80433.5±6.4±6.9 MeV, is the most precise so far, and shows a discrepancy of 76 with Standard Model expectations.

In this work we propose a new method to measure the evolution of the neutron skin thickness between different isotopes. We consider antiproton–nucleus interactions close to the production threshold of ΛΛ̅ and Σ − Λ̅ pairs. At low energies, ΛΛ̅ pairs are produced in p̅ + p collisions, while Σ − Λ̅ pairs can only be produced in p̅ + n interactions. Measuring these cross sections provides information on the neutron skin thickness.

The Facility for Antiproton and Ion Research, FAIR, is presently under construction near Darmstadt, Germany. Among other large-scale installations, the P ¯ ANDA (Antiproton annihilations in Darmstadt) experiment is designed to address pertinent questions of the strong interaction in the non-perturbative region. At P ¯ ANDA, an antiproton beam, with momenta between 1.5 GeV/c and 15 GeV/c, circulating in the high-energy storage ring HESR will interact with internal targets. High interaction rates and unprecedented momentum resolusion will allow for a high discovery potential and precision experiments. The detector system of P ¯ ANDA is optimised to meet the challenges of high-resolution hadron spectroscopy in formation and production with very good background suppression. At the same time, it meets the requirements of other parts of the physics program such as hyperon and hadron structure physics. The detector is reviewed and physics goals are presented.

A bstract We compute the decay spectrum for dark matter (DM) with masses above the scale of electroweak symmetry breaking, all the way to the Planck scale. For an arbitrary hard process involving a decay to the unbroken standard model, we determine the prompt distribution of stable states including photons, neutrinos, positrons, and antiprotons. These spectra are a crucial ingredient in the search for DM via indirect detection at the highest energies as being probed in current and upcoming experiments including IceCube, HAWC, CTA, and LHAASO. Our approach improves considerably on existing methods, for instance, we include all relevant electroweak interactions.

The coherent photoproduction of J/ψ and ψ′ mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J/ψ is reconstructed using the dilepton (l+l-) and proton–antiproton decay channels, while for the ψ′ the dilepton and the l+l-π+π- decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb-1. The results are compared with theoretical models for coherent J/ψ and ψ′ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6×10-4, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J/ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.

Hyperon production in \\(pp YY\\) reactions is one of the main parts of the \\(P\\)ANDA physics program. By colliding antiprotons and protons with HESR at FAIR, antihyperon hyperon pairs can be produced via the annihilation of light antiquark quark pairs and the production of \\(ss\\) pairs. Feasibility studies have been performed for a set of \\(pp YY\\) reactions. Reconstruction rates for these reactions at \\(P\\)ANDA have been estimated. In particular, the feasibility of measuring spin observables in the \\(pp _^+ _^-\\) reaction at p beam = 7.0 GeV/c is presented.

We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of single-inclusive hadron production data in electron–positron annihilation. This determination, performed at leading, next-to-leading, and next-to-next-to-leading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient χ2 minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higher-order QCD corrections significantly improves the description of the data, especially in the small-z region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.