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Un pequeño radio de carga de protones de un experimento de dispersión de electrones-protones
W Xiong1, A Gasparian2, H Gao1
1Duke University and Triangle Universities Nuclear Laboratory, Durham, NC, USA.
Nature
|November 8, 2019
Resumen
El rompecabezas del radio de protones persiste, pero este estudio
Área de la Ciencia:
- Física atómica, molecular y óptica
- Física nuclear
- La electrodinámica cuántica
Sus antecedentes:
- El radio de carga del protón (rp) se determina tradicionalmente por la dispersión electrón-protón y la espectroscopia de hidrógeno.
- Una discrepancia, conocida como el "rompecabezas de radio de protones", surgió en 2010 debido a los resultados de los experimentos de hidrógeno muónico.
- Las mediciones espectroscópicas recientes sobre el hidrógeno ordinario también muestran discrepancias, lo que indica problemas sin resolver.
Objetivo del estudio:
- Para medir con precisión el radio de carga del protón utilizando un nuevo método de dispersión de electrones-protones.
- Abordar el actual "rompecabezas del radio del protón" proporcionando nuevos datos experimentales.
- Investigar la discrepancia entre los diferentes valores experimentales y teóricos de rp.
Principales métodos:
- Empleó un experimento de dispersión de electrones-protones de alta precisión en el Laboratorio Jefferson (PRad).
- Utilizó un método libre de espectrómetro magnético para superar las limitaciones de experimentos anteriores.
- Implementado un objetivo de gas de hidrógeno sin ventanas para mediciones en ángulos de dispersión hacia adelante muy pequeños.
Principales resultados:
- Se midió el radio de carga del protón como rp = 0.831 ± 0.007 femtómetros.
- Este resultado es más pequeño que las mediciones de dispersión de electrones-protones de alta precisión más recientes.
- El valor medido es 2,7 desviaciones estándar más pequeñas que el promedio de todos los resultados de dispersión de electrones-protones anteriores.
Conclusiones:
- La nueva medición apoya los valores de radio de carga de protones más pequeños obtenidos de los experimentos de hidrógeno muónico.
- Los hallazgos se alinean con la constante de Rydberg revisada, una constante fundamental en la física.
- Esta investigación contribuye a resolver el antiguo "rompecabezas del radio del protón".
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