Graphic of the dead cone effect detected at CERN (European Particle Physics Laboratory) by ALICE (A Large Ion Collider Experiment). The effect occurs when a charm quark (c) in a parton shower loses energy by emitting radiation in the form of gluons (g). For angles smaller than the ratio of the quarks mass (m) and energy (E), the shower displays a dead cone of suppressed radiation around the quark. As the parton shower proceeds, gluons are emitted at smaller angles and the energy of the quark decreases, resulting in larger dead cones of suppressed gluon emission. Quantum chromodynamics predicted the dead cone effect in the 1990s as part of the strong force theory. This result directly confirms this feature of the theory and also exposes the mass of the charm quark.
| px | px | dpi | = | cm | x | cm | = | MB |
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TOP29675989
Source:
達志影像
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RM
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Editorial use only. This image may not be used to state or imply endorsement by CERN or CERN employees of any product, activity or service. Not to be used in a military context.
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