New physics and tau $g-2$ using LHC heavy ion collisions

Abstract

The anomalous magnetic moment of the tau lepton $a_{\tau }=(g_{\tau }-2)/2$ strikingly evades measurement, but is highly sensitive to new physics such as compositeness or supersymmetry. We propose using ultraperipheral heavy ion collisions at the LHC to probe modified magnetic $\delta a_{\tau }$ and electric dipole moments $\delta d_{\tau }$. We introduce a suite of one electron/muon plus track(s) analyses, leveraging the exceptionally clean photon fusion $\gamma \gamma \to \tau \tau$ events to reconstruct both leptonic and hadronic tau decays sensitive to $\delta a_{\tau },\delta d_{\tau }$. Assuming 10% systematic uncertainties, the current 2 nb${}^{-1}$ lead-lead dataset could already provide constraints of $-0.0080<a_{\tau }<0.0046$ at 68% CL. This surpasses 15 year old lepton collider precision by a factor of three while opening novel avenues to new physics.

5 pages, 3 figures + bibliography and appendices

References in corpus (17)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Measurement of the fine-structure constant as a test of the Standard Model
• New determination of the fine structure constant and test of the quantum electrodynamics
• A new evaluation of the hadronic vacuum polarisation contributions to the muon anomalous magnetic moment and to $\mathbf{\alpha }({\mathbf{m}}_{\mathbf{Z}}^2)$
• Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast })$ with a semileptonic tagging method
• Axion-like particles, lepton-flavor violation and a new explanation of $a_{\mu }$ and $a_e$
• Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast })$ with a semileptonic tagging method
• Measurement of the exclusive $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$ process in proton--proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Possibility of Determining $\tau$ Lepton Electromagnetic Moments in $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ Process at the CERN-LHC
• Splitting Mass Spectra and Muon g-2 in Higgs-Anomaly Mediation
• Detection of two-photon exclusive production of supersymmetric pairs at the LHC
• Reconciling dark matter, $R_{K^{(\ast )}}$ anomalies and $(g-2{)}_{\mu }$ in an $L_{\mu }-L_{\tau }$ scenario
• Novel method for the direct measurement of the tau lepton dipole moments
• $H\to {\tau }^{+}{\tau }^{-}\gamma$ as a Probe of the $\tau$ Magnetic Dipole Moment
• Feasibility at the LHC, FCC-he and CLIC for sensitivity estimates on anomalous $\tau$-lepton couplings
• High energy photon interactions at the LHC
• A New Approach for Measuring the Muon Anomalous Magnetic Moment and Electric Dipole Moment

Cited by in corpus (27)

• Anomalous electromagnetic moments of $\tau$ lepton in $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ reaction in Pb+Pb collisions at the LHC
• gamma-UPC: Automated generation of exclusive photon-photon processes in ultraperipheral proton and nuclear collisions with varying form factors
• Observation and measurement of forward proton scattering in association with lepton pairs produced via the photon fusion mechanism at ATLAS
• Tau Neutrinos in the Next Decade: from GeV to EeV
• Observation of the $\gamma \gamma \to \tau \tau$ process in Pb+Pb collisions and constraints on the $\tau$-lepton anomalous magnetic moment with the ATLAS detector
• Towards testing the magnetic moment of the tau at one part per million
• Overview of high-density QCD studies with the CMS experiment at the LHC
• Observation of $\gamma \gamma$ $\to$ $\tau \tau$ in proton-proton collisions and limits on the anomalous electromagnetic moments of the $\tau$ lepton
• Forbidden Dark Matter Annihilations into Standard Model Particles
• Opportunities for new physics searches with heavy ions at colliders
• Observation of $\tau$ lepton pair production in ultraperipheral lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Report on Progress in Physics: Observation of the Breit-Wheeler Process and Vacuum Birefringence in Heavy-Ion Collisions
• Leptonic anomalous magnetic moments in $\nu$SMEFT
• Exciting Ions: a Systematic Treatment of Ultraperipheral Heavy Ion Collisions with Nuclear Breakup
• Radiative lepton mass and muon $g-2$ with suppressed lepton flavor and CP violations
• A new calculation of semi-exclusive axion-like particle production at the LHC
• Minimal realization of light thermal Dark Matter
• New opportunities at the photon energy frontier
• Strategy to measure tau $g-2$ via photon fusion in LHC proton collisions
• Tau $g-2$ at $e^{-}{e}^{+}$ colliders with momentum dependent form factor
• Light new physics and the $\tau$ lepton dipole moments: prospects at Belle II
• Extended thermal cycling of ATLAS ITk strip modules with and without stress mitigating interposers
• Polarized tau decay and CP violation in ultraperipheral heavy-ion collisions
• Feasibility of tau g-2 measurements in ultra-peripheral collisions of heavy ions
• Probing the Tau Anomalous Magnetic Moment at Colliders: From Ultra-Peripheral Collisions to the Precision Frontier
• Upcgen: a Monte Carlo simulation program for dilepton pair production in ultra-peripheral collisions of heavy ions
• Linearly Polarized Photon Fusion as a Precision Probe of the Tau Lepton Dipole Moments at Lepton Colliders