Does a meson that's made of a charm-antistrange quark pair exist? If so, what's it called?
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Executive summary
Yes — a meson composed of a charm quark and an antistrange quark exists and is conventionally called the D_s (D-sub-s) meson, with the positively charged ground state usually written D_s^+ and its antiparticle D_s^-; experimental collaborations such as ALICE routinely report measurements of D_s^+ production in high-energy collisions [1]. These charm–strange mesons are part of the family of D mesons and have multiple spin and excitation states that experimentalists and theorists study to probe hadronisation and the strong force [2] [3].
1. What the particle is and how it’s named
The particle formed by a charm quark (c) bound to an antistrange quark (s̄) is called a D_s meson; the positively charged member of that family is denoted D_s^+ (containing c s̄) while its charge-conjugate partner is D_s^- (containing c̄ s) — these are classified among the “open-charm” mesons rather than hidden-charm charmonium states [3] [2].
2. How experiments see it and why it matters
Large collider experiments have measured D_s^+ production and behaviour in a variety of environments; for example the ALICE collaboration reported production of D_s^+ mesons in Pb–Pb collisions at √s_NN = 5.02 TeV, using those yields to probe hadronisation mechanisms such as charm-quark recombination with abundant strange quarks in the quark–gluon plasma [1]. Such measurements are interpreted with transport and hydrodynamic models to test whether charm quarks hadronise via fragmentation in the vacuum or recombine with light quarks in the medium, with the D_s^+/D^0 ratios providing a sensitive observable [1].
3. Variants, excitations and a short taxonomy
The D_s system is not a single single-state object but a family: ground-state pseudoscalars (D_s), vector excitations (D_s^*), and several excited states have been observed or searched for, and historically experiments have catalogued several D_s versions differing by spin and mass; reporting notes that “physicists had known of four versions” before additional surprises appeared [3] [2]. Experimental programmes at CERN and elsewhere continue to refine masses, widths and decay modes to decide whether some observed peaks are conventional quark–antiquark mesons or more exotic structures.
4. Decays and phenomenology that tie to other fields
D_s mesons participate in weak decays and can be used as probes of weak-interaction couplings and hadronic effects; for instance, D_s^+ decays to τ^+ ντ with an appreciable branching fraction, a channel cited in discussions about kinematics of tau decays and the lightest charm-containing hadrons [4]. Their decay patterns and lifetimes are complicated by strong-interaction binding effects, which make precision theoretical calculations of charm decays challenging and a subject of active research [5].
5. Alternative interpretations and exotic neighbours
While the c s̄ combination is uncontroversial and corresponds to the D_s mesons, recent LHC experiments have also revealed exotic states — tetraquarks and molecular-like resonances — that blur the simple quark–antiquark picture; LHCb and CMS have reported tetraquark-like states containing charm in configurations that do not reduce to a single c s̄ pair, reminding that not all peaks in D-containing final states are necessarily conventional D_s excitations [6] [7]. Thus experimental context and amplitude analyses are necessary to assign a observed peak to a canonical D_s meson rather than an exotic multiquark state [8].
6. What sources show and what they do not
Contemporary CERN reporting and science journalism explicitly name and measure D_s^+ mesons and discuss their role in heavy-ion physics and spectroscopy [1] [2] [8], and other summaries note the established existence of multiple D_s states [3]. The provided sources do not attempt a full PDG-style listing of all D_s excitations or give every mass and width value, so precise numerical properties and the latest world averages are not asserted here because they are not contained in the supplied reporting [3] [8].