Adam Martin
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Adam Martin has a total of 1000 co-authors. Here are the top co-authors by number of shared publications:
- Antonio Delgado
University of Notre Dame
21 shared publications - Runqing Wang
University of Notre Dame
9 shared publications - Kenneth Lane
Department of Physics Boston University 590 Commonwealth Avenue 02215 Boston Massachusetts
8 shared publications - Baradhwaj Coleppa
Indian Institute of Technology Gandhinagar
6 shared publications - Carlos Alvarado
Department of Physics, University of Notre Dame, 225 Nieuwland Hall, Notre Dame, Indiana 46556, USA
6 shared publications - Elizabeth H. Simmons
Department of Physics and Astronomy Michigan State University East Lansing U.S.A
6 shared publications
Latest Publications
- Open Access
- 9 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11)
EFT validity and truncation uncertainty from few nuisance parameters
A bstract: An observable in an Effective Field Theory (EFT) is an expansion in a set of small parameters, no different than any other perturbation series. Truncating such a series expansion leaves the leading dropped term as the dominant source of error, and that term itself contains a calculable portion. We explore the partial calculation of this next-order error, available at dim-6 2 in SMEFT with no additional tools needed to simulate it, and explore how to efficiently use that partial calculation to model the next-order uncertainty in full using a minimal number of nuisance parameters. This estimate of the uncertainty of the EFT signal rate naturally imposes EFT validity by ensuring that bounds are driven by kinematic regions where truncation uncertainties are parametrically smaller than the signal. We incorporate the calculable dim-6 2 piece into the signal and cover the remaining higher-dimension uncertainty with a small set of nuisance parameters derived from a scan over Wilson-coefficient values. Our algorithm to determine the relevant nuisance parameters and distributions is automation-friendly and applies to arbitrary truncation choices. We then provide multiple examples of its implementation in high-energy collider processes focused on SMEFT truncated at 𝒪(Λ −2 ), where the dim-6 2 piece is used to estimate the full 𝒪(Λ −4 ) dependence. In the examples considered here the reduction of nuisance parameters is appreciable, generically reducing the nuisance parameter count by an order of magnitude compared to naïve estimates.
- 9 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11)
Open AccessEFT validity and truncation uncertainty from few nuisance parameters
A bstract: An observable in an Effective Field Theory (EFT) is an expansion in a set of small parameters, no different than any other perturbation series. Truncating such a series expansion leaves the leading dropped term as the dominant source of error, and that term itself contains a calculable portion. We explore the partial calculation of this next-order error, available at dim-6 2 in SMEFT with no additional tools needed to simulate it, and explore how to efficiently use that partial calculation to model the next-order uncertainty in full using a minimal number of nuisance parameters. This estimate of the uncertainty of the EFT signal rate naturally imposes EFT validity by ensuring that bounds are driven by kinematic regions where truncation uncertainties are parametrically smaller than the signal. We incorporate the calculable dim-6 2 piece into the signal and cover the remaining higher-dimension uncertainty with a small set of nuisance parameters derived from a scan over Wilson-coefficient values. Our algorithm to determine the relevant nuisance parameters and distributions is automation-friendly and applies to arbitrary truncation choices. We then provide multiple examples of its implementation in high-energy collider processes focused on SMEFT truncated at 𝒪(Λ −2 ), where the dim-6 2 piece is used to estimate the full 𝒪(Λ −4 ) dependence. In the examples considered here the reduction of nuisance parameters is appreciable, generically reducing the nuisance parameter count by an order of magnitude compared to naïve estimates.
- Open Access
- 18 September 2026
- Published by Springer Nature in The European Physical Journal C
- Vol. 86 (9) , 1084
Probing EFT breakdown in the tails of $W^+ W^-$ observablesWe test clipping effective field theory (EFT) simulations as a method of ensuring EFT validity. The procedure imposes that, at the level of the simulation, the invariant mass of a $$W^+W^-$$ pair $$M_{WW}$$ is less than the new physics scale $$\Lambda $$ . We compare this to two other methods, comparison bin by bin of dimension-6 and dimension-8 squared contributions and implementing a cut on data. We find that setting $$M_{WW} < \Lambda $$ is not strict enough to ensure that the hierarchy of EFT operators is respected for dimension-6 and dimension-8 contributions. We also show that, even when using a stricter cut on $$M_{WW}$$ , due to different correlations between $$M_{WW}$$ and $$M_{e\mu }$$ at different EFT orders, the bins in $$M_{e\mu }$$ (the invariant mass of the leptons originating from W decays) used in an EFT fit may not truly be in the regime of EFT validity when performing a dimension-6 fit with $$M_{WW} < \Lambda $$ . We also explore the correlations of three transverse mass observables: $$M_{T1}, M_{T2}$$ and $$M_{T3}$$ , finding that $$M_{T1}$$ and $$M_{T3}$$ follow the $$M_{WW}$$ distribution more closely than $$M_{e\mu }$$ . We present sensitivity studies using both the $$M_{T3}$$ distribution and $$M_{e\mu }$$ distribution. We test implementing an experimental cut on $$M_{T3}$$ in place of clipping the EFT simulation at $$M_{WW} < \Lambda $$ . We finally comment that adding $$M_{WW} < \Lambda $$ cuts only to the EFT simulation could be interpreted as modifying the SMEFT expansion by a form factor and could therefore impact the model independence of EFT fits under this procedure.- 18 September 2026
- Published by Springer Nature in The European Physical Journal C
- Vol. 86 (9) , 1084
Open AccessProbing EFT breakdown in the tails of $W^+ W^-$ observablesWe test clipping effective field theory (EFT) simulations as a method of ensuring EFT validity. The procedure imposes that, at the level of the simulation, the invariant mass of a $$W^+W^-$$ pair $$M_{WW}$$ is less than the new physics scale $$\Lambda $$ . We compare this to two other methods, comparison bin by bin of dimension-6 and dimension-8 squared contributions and implementing a cut on data. We find that setting $$M_{WW} < \Lambda $$ is not strict enough to ensure that the hierarchy of EFT operators is respected for dimension-6 and dimension-8 contributions. We also show that, even when using a stricter cut on $$M_{WW}$$ , due to different correlations between $$M_{WW}$$ and $$M_{e\mu }$$ at different EFT orders, the bins in $$M_{e\mu }$$ (the invariant mass of the leptons originating from W decays) used in an EFT fit may not truly be in the regime of EFT validity when performing a dimension-6 fit with $$M_{WW} < \Lambda $$ . We also explore the correlations of three transverse mass observables: $$M_{T1}, M_{T2}$$ and $$M_{T3}$$ , finding that $$M_{T1}$$ and $$M_{T3}$$ follow the $$M_{WW}$$ distribution more closely than $$M_{e\mu }$$ . We present sensitivity studies using both the $$M_{T3}$$ distribution and $$M_{e\mu }$$ distribution. We test implementing an experimental cut on $$M_{T3}$$ in place of clipping the EFT simulation at $$M_{WW} < \Lambda $$ . We finally comment that adding $$M_{WW} < \Lambda $$ cuts only to the EFT simulation could be interpreted as modifying the SMEFT expansion by a form factor and could therefore impact the model independence of EFT fits under this procedure. - Open Access
- 14 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8) , 126
Higgs decays to four leptons to $ \mathcal{O}\left(1/{\Lambda}^4\right) $ in SMEFTA bstract: We study the decays $$ h\to \ell \overline{\ell}\left(Z\to {\ell}^{\prime }{\overline{\ell}}^{\prime}\right) $$ and $$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ within the SMEFT framework and including effects up to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ , where Λ is the new physics scale suppressing higher dimensional operators. To work to this order, we must include the square of dimension-six operators and the interference of dimension-eight operators with the Standard Model. We study angular asymmetries and other differential decay observables and determine which are most sensitive to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ effects. While new kinematic structures arising in higher dimensional operators have the potential to induce novel angular dependency, we find this does not occur for $$ h\to \ell \overline{\ell}\left(Z\to {\ell}^{\prime }{\overline{\ell}}^{\prime}\right) $$ . For $$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ , new angular dependencies do arise at $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ , though they require a fully reconstructible (meaning we can go to the Higgs rest frame) final state. For non-reconstructible final states such as $$ \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ , we must study Higgs production and decay together with the appropriate observables, which we find obscures the new angular effects.- 14 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8) , 126
Open AccessHiggs decays to four leptons to $ \mathcal{O}\left(1/{\Lambda}^4\right) $ in SMEFTA bstract: We study the decays $$ h\to \ell \overline{\ell}\left(Z\to {\ell}^{\prime }{\overline{\ell}}^{\prime}\right) $$ and $$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ within the SMEFT framework and including effects up to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ , where Λ is the new physics scale suppressing higher dimensional operators. To work to this order, we must include the square of dimension-six operators and the interference of dimension-eight operators with the Standard Model. We study angular asymmetries and other differential decay observables and determine which are most sensitive to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ effects. While new kinematic structures arising in higher dimensional operators have the potential to induce novel angular dependency, we find this does not occur for $$ h\to \ell \overline{\ell}\left(Z\to {\ell}^{\prime }{\overline{\ell}}^{\prime}\right) $$ . For $$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ , new angular dependencies do arise at $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ , though they require a fully reconstructible (meaning we can go to the Higgs rest frame) final state. For non-reconstructible final states such as $$ \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ , we must study Higgs production and decay together with the appropriate observables, which we find obscures the new angular effects. - Open AccessHiggs decays to four leptons to $\mathcal{O}(1/Λ^4)$ in SMEFTWe study the decays $h \to \ell \bar{\ell} \left(Z \to \ell' \bar{\ell'}\right)$ and $h\to\ell\barν_\ellν_{\ell'}\bar{\ell'}$ within the SMEFT framework and including effects up to $\mathcal O(1/Λ^4)$, where $Λ$ is the new physics scale suppressing higher dimensional operators. To work to this order, we must include the square of dimension-six operators and the interference of dimension-eight operators with the Standard Model. We study angular asymmetries and other differential decay observables and determine which are most sensitive to $\mathcal O(1/Λ^4)$ effects. While new kinematic structures arising in higher dimensional operators have the potential to induce novel angular dependency, we find this does not occur for $h\to\ell\bar{\ell}\left(Z\xrightarrow{}\ell'\bar{\ell'}\right)$. For $h \to \ell \barν_\ell ν_{\ell'} \bar{\ell'}$, new angular dependencies do arise at $\mathcal O(1/Λ^4)$, though they require a fully reconstructible (meaning we can go to the Higgs rest frame) final state. For non-reconstructible final states such as $\ell \barν_\ell ν_{\ell'} \bar{\ell'}$, we must study Higgs production and decay together with the appropriate observables, which we find obscures the new angular effects.Open AccessHiggs decays to four leptons to $\mathcal{O}(1/Λ^4)$ in SMEFTWe study the decays $h \to \ell \bar{\ell} \left(Z \to \ell' \bar{\ell'}\right)$ and $h\to\ell\barν_\ellν_{\ell'}\bar{\ell'}$ within the SMEFT framework and including effects up to $\mathcal O(1/Λ^4)$, where $Λ$ is the new physics scale suppressing higher dimensional operators. To work to this order, we must include the square of dimension-six operators and the interference of dimension-eight operators with the Standard Model. We study angular asymmetries and other differential decay observables and determine which are most sensitive to $\mathcal O(1/Λ^4)$ effects. While new kinematic structures arising in higher dimensional operators have the potential to induce novel angular dependency, we find this does not occur for $h\to\ell\bar{\ell}\left(Z\xrightarrow{}\ell'\bar{\ell'}\right)$. For $h \to \ell \barν_\ell ν_{\ell'} \bar{\ell'}$, new angular dependencies do arise at $\mathcal O(1/Λ^4)$, though they require a fully reconstructible (meaning we can go to the Higgs rest frame) final state. For non-reconstructible final states such as $\ell \barν_\ell ν_{\ell'} \bar{\ell'}$, we must study Higgs production and decay together with the appropriate observables, which we find obscures the new angular effects.
- Open Access
- 2 November 2025
- Published by Elsevier in Nuclear Physics B
- Vol. 1021
Phenomenology of fractionally charged particles: Two reps are better than one
- 2 November 2025
- Published by Elsevier in Nuclear Physics B
- Vol. 1021
Open AccessPhenomenology of fractionally charged particles: Two reps are better than one
- Open Access
- 25 August 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (8) , 1-21
Non-factorizable superamplitudes for massive $ \mathcal{N} $ = 1 superstatesIn this paper we study non-factorizable $$ \mathcal{N} $$ = 1 superamplitudes for massive chiral superstates. We demonstrate how little group scaling and the supersymmetric Ward identities determine the form of non-factorizable massless superamplitudes, then extrapolate to massive superamplitudes by requiring they reduce to the massless form when we send all masses to zero. This technique does not depend on whether or not the superstates are self-conjugate (so that the fermionic components are either Dirac or Majorana) or whether the superamplitude is dressed with a form-factor.- 25 August 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (8) , 1-21
Open AccessNon-factorizable superamplitudes for massive $ \mathcal{N} $ = 1 superstatesIn this paper we study non-factorizable $$ \mathcal{N} $$ = 1 superamplitudes for massive chiral superstates. We demonstrate how little group scaling and the supersymmetric Ward identities determine the form of non-factorizable massless superamplitudes, then extrapolate to massive superamplitudes by requiring they reduce to the massless form when we send all masses to zero. This technique does not depend on whether or not the superstates are self-conjugate (so that the fermionic components are either Dirac or Majorana) or whether the superamplitude is dressed with a form-factor. - Open Access
Phenomenology of Fractionally Charged Particles: Two Reps Are Better Than One
We continue our study of fractionally charged particles (FCPs) -- particles carrying electric charge a multiple of $e/6$. Discovering an FCP would inform us about both Standard Model physics (what the true gauge group and the one-form global symmetry are) and Beyond the Standard Model physics (ruling out many unified theories), which makes them a high-stakes target for collider searches. Here we find that with two FCPs there are vastly richer phenomenologies compared to the single-particle extensions we previously studied. Stringent constraints on colored FCPs can be dramatically weakened when decays are open; conversely the cross sections of the least visible species can be enlarged by up to $\sim 10^3$, increasing their discovery potential enormously at the LHC and milliQan. Overall, these simple models motivate performing searches for FCPs produced along with jets or leptons, and highlight 'free' discovery potential in reanalyzing existing missing-energy datasets for low-quality tracks.Open AccessPhenomenology of Fractionally Charged Particles: Two Reps Are Better Than One
We continue our study of fractionally charged particles (FCPs) -- particles carrying electric charge a multiple of $e/6$. Discovering an FCP would inform us about both Standard Model physics (what the true gauge group and the one-form global symmetry are) and Beyond the Standard Model physics (ruling out many unified theories), which makes them a high-stakes target for collider searches. Here we find that with two FCPs there are vastly richer phenomenologies compared to the single-particle extensions we previously studied. Stringent constraints on colored FCPs can be dramatically weakened when decays are open; conversely the cross sections of the least visible species can be enlarged by up to $\sim 10^3$, increasing their discovery potential enormously at the LHC and milliQan. Overall, these simple models motivate performing searches for FCPs produced along with jets or leptons, and highlight 'free' discovery potential in reanalyzing existing missing-energy datasets for low-quality tracks. - Open Access
- 12 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-40
Dimension-8 operators in W+W− production via gluon fusion
We investigate the impact of dimension-8 operators on W + W − production at the LHC for the incoming gluon-gluon channel. To this end, we have identified all dimension-8 CP-even operators contributing to the process in question, and computed the corresponding tree-level helicity amplitudes for fully-leptonic decays of the W bosons. These are implemented in the program MCFM-RE, which automatically incorporates the effect of a jet-veto to reduce the otherwise overwhelming $$ t\overline{t} $$ background. We find that, unless we break the hierarchy of the effective field theory (EFT), the interference of the dimension-8 operators with the Standard Model is negligible across the considered distributions. This justifies including the square of dimension-6 operators when performing EFT fits with this channel. We then present new constraints on CP-even and CP-odd dimension-6 operators within the EFT regime. Lastly, we postulate a scenario in which the hierarchy of the EFT is broken, justified by the strong constraints on dimension-6 operators from existing on-shell Higgs data. In this scenario, we discuss the constraints that can be reasonably set on CP-even dimension-8 operators with current and future data. We remark that the effect of the jet-veto on the ability to constrain new physics in the W + W − channel is quite dramatic and must be properly taken into account.- 12 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-40
Open AccessDimension-8 operators in W+W− production via gluon fusion
We investigate the impact of dimension-8 operators on W + W − production at the LHC for the incoming gluon-gluon channel. To this end, we have identified all dimension-8 CP-even operators contributing to the process in question, and computed the corresponding tree-level helicity amplitudes for fully-leptonic decays of the W bosons. These are implemented in the program MCFM-RE, which automatically incorporates the effect of a jet-veto to reduce the otherwise overwhelming $$ t\overline{t} $$ background. We find that, unless we break the hierarchy of the effective field theory (EFT), the interference of the dimension-8 operators with the Standard Model is negligible across the considered distributions. This justifies including the square of dimension-6 operators when performing EFT fits with this channel. We then present new constraints on CP-even and CP-odd dimension-6 operators within the EFT regime. Lastly, we postulate a scenario in which the hierarchy of the EFT is broken, justified by the strong constraints on dimension-6 operators from existing on-shell Higgs data. In this scenario, we discuss the constraints that can be reasonably set on CP-even dimension-8 operators with current and future data. We remark that the effect of the jet-veto on the ability to constrain new physics in the W + W − channel is quite dramatic and must be properly taken into account. - Open Access
Non-factorizable Superamplitudes for Massive N = 1 Superstates
In this paper we study non-factorizable N = 1 superamplitudes for massive chiral superstates. We demonstrate how little group scaling and the supersymmetric Ward identities determine the form of non-factorizable massless superamplitudes, then extrapolate to massive superamplitudes by requiring they reduce to the massless form when we send all masses to zero. This technique does not depend on whether or not the superstates are self-conjugate (so that the fermionic components are either Dirac or Majorana) or whether the superamplitude is dressed with a form-factor.
Open AccessNon-factorizable Superamplitudes for Massive N = 1 Superstates
In this paper we study non-factorizable N = 1 superamplitudes for massive chiral superstates. We demonstrate how little group scaling and the supersymmetric Ward identities determine the form of non-factorizable massless superamplitudes, then extrapolate to massive superamplitudes by requiring they reduce to the massless form when we send all masses to zero. This technique does not depend on whether or not the superstates are self-conjugate (so that the fermionic components are either Dirac or Majorana) or whether the superamplitude is dressed with a form-factor.
- Open Access
- 6 February 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (2) , 1-33
Energy-enhanced dimension eight SMEFT effects in VBF Higgs production
We study Higgs boson production via vector boson fusion at the LHC, focusing on the process pp → H + jj and capturing the leading energy-enhanced contributions within the Standard Model Effective Field Theory (SMEFT) up to order 1/Λ4. Employing energy-scaling arguments, we predict the magnitude of each higher-dimensional operator’s contribution. Utilizing the geometric formulation of SMEFT, our analysis incorporates dimension-eight operators not previously considered. We find that the kinematics of vector boson fusion — characterized by two highly forward jets — tend to suppress contributions from higher-dimensional operators, requiring a lower scale Λ for SMEFT effects to become observable. This suggests that the SMEFT remains valid for lower Λ than expected. Combined with the fact that LEP constrains the dimension-six operators with the most considerable impact on vector boson fusion, a regime exists where dimension-eight operators can have significant effects. In many cases, these dimension-eight operators also influence associated production processes like pp → HV(jj), though differences in analysis cuts and kinematics mean this is not always the case. Our findings provide insights that could refine the search for SMEFT signals in collider experiments.
- 6 February 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (2) , 1-33
Open AccessEnergy-enhanced dimension eight SMEFT effects in VBF Higgs production
We study Higgs boson production via vector boson fusion at the LHC, focusing on the process pp → H + jj and capturing the leading energy-enhanced contributions within the Standard Model Effective Field Theory (SMEFT) up to order 1/Λ4. Employing energy-scaling arguments, we predict the magnitude of each higher-dimensional operator’s contribution. Utilizing the geometric formulation of SMEFT, our analysis incorporates dimension-eight operators not previously considered. We find that the kinematics of vector boson fusion — characterized by two highly forward jets — tend to suppress contributions from higher-dimensional operators, requiring a lower scale Λ for SMEFT effects to become observable. This suggests that the SMEFT remains valid for lower Λ than expected. Combined with the fact that LEP constrains the dimension-six operators with the most considerable impact on vector boson fusion, a regime exists where dimension-eight operators can have significant effects. In many cases, these dimension-eight operators also influence associated production processes like pp → HV(jj), though differences in analysis cuts and kinematics mean this is not always the case. Our findings provide insights that could refine the search for SMEFT signals in collider experiments.