Collider Constraints on Massive Gravitons

Abstract

Abstract We explore the potential for discovering massive graviton-like spin-2 particles, interacting with standard model fields. These particles are produced in collisions involving photons at the Large Hadron Collider (LHC) and electron-positron ( $$e^{+}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> $$e^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> </mml:math> ) collisions. Our investigation utilizes an effective theory, both with and without universal couplings. Specifically, we focus on a massive graviton, denoted as G, that is coupled to the electromagnetic field. The decay of G leads to a resonant excess of diphotons over the light-by-light scattering continuum at the LHC, as well as triphoton final states in $$e^{+}e^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> </mml:math> colliders. By analyzing existing data, we establish the exclusion limits on the graviton-photon coupling, reaching down to approximately $$g_{G\gamma } \approx 1\text{--}0.05 \, \text{TeV}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Gγ</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≈</mml:mo> <mml:mn>1</mml:mn> <mml:mtext>–</mml:mtext> <mml:mn>0.05</mml:mn> <mml:mspace/> <mml:msup> <mml:mrow> <mml:mtext>TeV</mml:mtext> </mml:mrow> <mml:mrow> <mml:mn>−1</mml:mn> </mml:mrow> </mml:msup> </mml:math> for graviton masses ranging from $$m_{G}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>G</mml:mi> </mml:mrow> </mml:msub> </mml:math> $$\approx $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>≈</mml:mo> </mml:math> 100 MeV to 2 TeV. With their expected full integrated, in the low-mass range, significant enhancements are anticipated at Belle II, potentially improving these bounds by a factor of 100. Conversely, at higher masses, the High-Luminosity Large Hadron Collider (HL-LHC) is expected to enhance limits by a factor of 4.