Physicists observe rare photon production at LHC, confirming standard model predictions
Researchers at CERN have directly observed a rare process where photons are produced alongside jets through electroweak interactions—a phenomenon predicted by physics theory but never clearly seen before. The finding validates core models of particle behavior and strengthens confidence in detector precision, with implications for future searches for physics beyond current theory.
Originaltitel: Measurements of electroweak production of a photon in association with two jets in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV
A bstract The first observation of electroweak production of a photon in association with two forward jets in proton-proton collisions is presented. The measurement uses data recorded by the CMS experiment at the LHC during 2016–2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . The analysis is performed in a region enriched in photon production via vector boson fusion, with a requirement on the transverse momentum of the photon to exceed 200 GeV. The cross section is measured to be $$ {202}_{-32}^{+36} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>202</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>32</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>36</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> fb, at a significance with respect to the null hypothesis that exceeds five standard deviations. This is in agreement with the standard model prediction of $$ {177}_{-12}^{+13} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>177</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>12</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> fb. Differential cross sections are measured as a function of various observables. Limits are set on dimension-6 effective field theory operators that contribute to the WWγ interaction. The observed 95% confidence intervals for the corresponding Warsaw basis Wilson coefficients c W and c HWB are [ − 0 . 11 , 0 . 16] and [ − 1 . 6 , 1 . 5], respectively.