Michael Williams
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
Research Interests
Michael Williams has a total of 1000 co-authors. Here are the top co-authors by number of shared publications:
- Philip Ilten
University of Cincinnati
124 shared publications - Adrián Casais Vidal
Massachusetts Institute of Technology
112 shared publications - Alexandre Brea Rodriguez
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL)
112 shared publications - Biplab Dey
Eötvös Loránd University
112 shared publications - Daniel Johnson
University of Birmingham
112 shared publications - Eli Ben Haim
Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Sorbonne Université, CNRS/IN2P3
112 shared publications
Latest Publications
- Open Access
- 26 October 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (10)
Search for CP violation in D+ → ϕπ+ decays
A bstract: A search for charge-parity ( CP ) violation in the Cabibbo-suppressed D + → ϕπ + decay is presented, using proton-proton collision data corresponding to an integrated luminosity of 6 fb − 1 , collected at a centre-of-mass energy of 13 TeV with the LHCb detector during Run 2. An abundant sample of $$ {D}^{+}\to {K}_{\mathrm{S}}^0{\pi}^{+} $$ decays is employed to correct for asymmetries arising from the production of the charmed meson and from detection effects associated with the charged pion accompanying the ϕ meson. Asymmetries induced by interference of multiple processes, such as neutral kaon mixing, regeneration of neutral kaons, and interference between the Cabibbo-favoured $$ {D}^{+}\to {\overline{K}}^0{\pi}^{+} $$ and the doubly Cabibbo-suppressed D + → K 0 π + decay, are subtracted. The direct CP asymmetry in the D + → ϕπ + decay is measured to be $$ {a}_{CP}\left({D}^{+}\to \phi {\pi}^{+}\right)=\left(0.1\pm 4.9\left(\mathrm{stat}\right)\pm 2.4\left(\mathrm{syst}\right)\right)\times {10}^{-4}. $$ For the first time at a hadron collider, the modulus of the ratio and the relative strong phase of the D + → K 0 π + to $$ {D}^{+}\to {\overline{K}}^0{\pi}^{+} $$ decay amplitudes are also investigated. Two-dimensional confidence intervals are reported for these parameters.- 26 October 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (10)
Open AccessSearch for CP violation in D+ → ϕπ+ decays
A bstract: A search for charge-parity ( CP ) violation in the Cabibbo-suppressed D + → ϕπ + decay is presented, using proton-proton collision data corresponding to an integrated luminosity of 6 fb − 1 , collected at a centre-of-mass energy of 13 TeV with the LHCb detector during Run 2. An abundant sample of $$ {D}^{+}\to {K}_{\mathrm{S}}^0{\pi}^{+} $$ decays is employed to correct for asymmetries arising from the production of the charmed meson and from detection effects associated with the charged pion accompanying the ϕ meson. Asymmetries induced by interference of multiple processes, such as neutral kaon mixing, regeneration of neutral kaons, and interference between the Cabibbo-favoured $$ {D}^{+}\to {\overline{K}}^0{\pi}^{+} $$ and the doubly Cabibbo-suppressed D + → K 0 π + decay, are subtracted. The direct CP asymmetry in the D + → ϕπ + decay is measured to be $$ {a}_{CP}\left({D}^{+}\to \phi {\pi}^{+}\right)=\left(0.1\pm 4.9\left(\mathrm{stat}\right)\pm 2.4\left(\mathrm{syst}\right)\right)\times {10}^{-4}. $$ For the first time at a hadron collider, the modulus of the ratio and the relative strong phase of the D + → K 0 π + to $$ {D}^{+}\to {\overline{K}}^0{\pi}^{+} $$ decay amplitudes are also investigated. Two-dimensional confidence intervals are reported for these parameters. - Open Access
- 5 October 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (10)
Evidence for the decay $ {B}_s^0\to {\phi \eta}^{\prime } $A bstract: Using a dataset corresponding to an integrated luminosity of 9 fb − 1 collected in proton-proton collisions between 2011 and 2018 by the LHCb experiment, evidence is found for the decay $$ {B}_s^0\to {\phi \eta}^{\prime } $$ with 3 . 5 σ significance. The branching ratio relative to the $$ {B}_s^0\to \phi \phi $$ decay is determined to be ℛ = (3 . 56 ± 0 . 79 ± 0 . 18 ± 0 . 06) × 10 − 2 . This corresponds to a branching fraction, $$ \mathcal{B}\left({B}_s^0\to {\phi \eta}^{\prime}\right)=\left(0.66\pm 0.15\pm 0.03\pm 0.02\right)\times {10}^{-6} $$ where, in both cases, the first uncertainty is statistical, the second systematic, and the third due to external branching fractions.- 5 October 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (10)
Open AccessEvidence for the decay $ {B}_s^0\to {\phi \eta}^{\prime } $A bstract: Using a dataset corresponding to an integrated luminosity of 9 fb − 1 collected in proton-proton collisions between 2011 and 2018 by the LHCb experiment, evidence is found for the decay $$ {B}_s^0\to {\phi \eta}^{\prime } $$ with 3 . 5 σ significance. The branching ratio relative to the $$ {B}_s^0\to \phi \phi $$ decay is determined to be ℛ = (3 . 56 ± 0 . 79 ± 0 . 18 ± 0 . 06) × 10 − 2 . This corresponds to a branching fraction, $$ \mathcal{B}\left({B}_s^0\to {\phi \eta}^{\prime}\right)=\left(0.66\pm 0.15\pm 0.03\pm 0.02\right)\times {10}^{-6} $$ where, in both cases, the first uncertainty is statistical, the second systematic, and the third due to external branching fractions. - Open Access
- 4 September 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (9)
Search for τ− → μ−μ+μ− decays at the LHCb experiment with Run 2 data
A bstract: A search for the lepton-flavour-violating decay τ − → μ − μ + μ − is carried out using data collected by the LHCb experiment between 2016 and 2018 in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 . An upper limit of 1 . 9 (2 . 3) × 10 − 8 is set at the 90% (95%) confidence level on the branching fraction of the decay.
- 4 September 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (9)
Open AccessSearch for τ− → μ−μ+μ− decays at the LHCb experiment with Run 2 data
A bstract: A search for the lepton-flavour-violating decay τ − → μ − μ + μ − is carried out using data collected by the LHCb experiment between 2016 and 2018 in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 . An upper limit of 1 . 9 (2 . 3) × 10 − 8 is set at the 90% (95%) confidence level on the branching fraction of the decay.
- Open Access
- 19 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Measurement of the local and nonlocal amplitudes in B+ → K+μ+μ− decays
A bstract: This paper presents a thorough study of the local and nonlocal amplitudes in B + → K + μ + μ − transitions through an amplitude analysis of the dimuon mass spectrum of the decay. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb − 1 collected by the LHCb experiment during Run1 and Run2. This measurement employs a model that describes both one-particle and two-particle nonlocal amplitudes across the entirety of the dimuon mass spectrum, enabling the determination of both short- and long-distance contributions to the decay. The compatibility of the Wilson coefficient combinations $$ {C}_9+{C}_9^{\prime } $$ and $$ {C}_{10}+{C}_{10}^{\prime } $$ with the Standard Model prediction is found to vary between 1 . 6 σ and 4 σ , depending on the choice of local form factors.- 19 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Open AccessMeasurement of the local and nonlocal amplitudes in B+ → K+μ+μ− decays
A bstract: This paper presents a thorough study of the local and nonlocal amplitudes in B + → K + μ + μ − transitions through an amplitude analysis of the dimuon mass spectrum of the decay. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb − 1 collected by the LHCb experiment during Run1 and Run2. This measurement employs a model that describes both one-particle and two-particle nonlocal amplitudes across the entirety of the dimuon mass spectrum, enabling the determination of both short- and long-distance contributions to the decay. The compatibility of the Wilson coefficient combinations $$ {C}_9+{C}_9^{\prime } $$ and $$ {C}_{10}+{C}_{10}^{\prime } $$ with the Standard Model prediction is found to vary between 1 . 6 σ and 4 σ , depending on the choice of local form factors. - Open Access
- 6 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Measurement of CP asymmetries in $ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $ and $ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $ decaysA bstract: Measurements of the combined CP asymmetries in $$ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $$ and $$ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $$ decays are made using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . The measurements are found to be $$ {\displaystyle \begin{array}{l}{A}_{CP}\left({\overline{B}}^0\to {D}_s^{-}{D}^{+}\right)=0.0009\pm 0.0053\pm 0.0040,\\ {}{A}_{CP}\left({\overline{B}}_s^0\to {D}_s^{-}{D}^{-}\right)=0.103\pm 0.053\pm 0.010,\end{array}} $$ where the first and second uncertainties are statistical and systematic, respectively. This is the first measurement of this asymmetry in $$ {\overline{B}}_s^0 $$ decays, and the most precise measurement to date for $$ {\overline{B}}^0 $$ decays. Both measurements are found to be consistent with CP symmetry.- 6 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Open AccessMeasurement of CP asymmetries in $ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $ and $ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $ decaysA bstract: Measurements of the combined CP asymmetries in $$ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $$ and $$ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $$ decays are made using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . The measurements are found to be $$ {\displaystyle \begin{array}{l}{A}_{CP}\left({\overline{B}}^0\to {D}_s^{-}{D}^{+}\right)=0.0009\pm 0.0053\pm 0.0040,\\ {}{A}_{CP}\left({\overline{B}}_s^0\to {D}_s^{-}{D}^{-}\right)=0.103\pm 0.053\pm 0.010,\end{array}} $$ where the first and second uncertainties are statistical and systematic, respectively. This is the first measurement of this asymmetry in $$ {\overline{B}}_s^0 $$ decays, and the most precise measurement to date for $$ {\overline{B}}^0 $$ decays. Both measurements are found to be consistent with CP symmetry. - Open Access
- 5 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Observation of the charmless purely baryonic decay $ {\Lambda}_b^0\to \Lambda p\overline{p} $A bstract: A search for the charmless purely baryonic decay $$ {\Lambda}_b^0\to \Lambda p\overline{p} $$ is performed using proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of $$ \sqrt{s}=13 $$ TeV and corresponding to an integrated luminosity of 6 . 0 fb − 1 . The signal decay is observed with a significance of 5.1 standard deviations. Its branching fraction is measured for the first time, relative to that of the topologically similar decay $$ {\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-} $$ . Contributions from intermediate charmonium resonances decaying to the $$ p\overline{p} $$ and K + K − final states are explicitly excluded with a requirement on the invariant mass of the companion hadron system, $$ m\left(h\overline{h}\right)<2.85 $$ GeV, where h stands for a proton or a charged kaon. The relative branching fraction is found to be $$ \frac{\mathcal{B}\left({\Lambda}_b^0\to \Lambda p\overline{p}\right)}{\mathcal{B}\left({\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-}\right)}=\left(5.1\pm {1.3}_{\left(\mathrm{stat}\right)}\pm {0.3}_{\left(\mathrm{syst}\right)}\right)\times {10}^{-2}. $$- 5 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Open AccessObservation of the charmless purely baryonic decay $ {\Lambda}_b^0\to \Lambda p\overline{p} $A bstract: A search for the charmless purely baryonic decay $$ {\Lambda}_b^0\to \Lambda p\overline{p} $$ is performed using proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of $$ \sqrt{s}=13 $$ TeV and corresponding to an integrated luminosity of 6 . 0 fb − 1 . The signal decay is observed with a significance of 5.1 standard deviations. Its branching fraction is measured for the first time, relative to that of the topologically similar decay $$ {\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-} $$ . Contributions from intermediate charmonium resonances decaying to the $$ p\overline{p} $$ and K + K − final states are explicitly excluded with a requirement on the invariant mass of the companion hadron system, $$ m\left(h\overline{h}\right)<2.85 $$ GeV, where h stands for a proton or a charged kaon. The relative branching fraction is found to be $$ \frac{\mathcal{B}\left({\Lambda}_b^0\to \Lambda p\overline{p}\right)}{\mathcal{B}\left({\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-}\right)}=\left(5.1\pm {1.3}_{\left(\mathrm{stat}\right)}\pm {0.3}_{\left(\mathrm{syst}\right)}\right)\times {10}^{-2}. $$ - Open Access
- 5 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Measurement of γ using B± → DK± and B± → Dπ± decays with $ D\to {K}_{\mathrm{S}}^0{\pi}^{+}{\pi}^{-} $ and $ D\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $A bstract: A measurement of the CKM angle γ using the decay channels B ± → DK ± and B ± → Dπ ± , where the D meson decays to $$ D\to {K}_{\mathrm{S}}^0{\pi}^{+}{\pi}^{-} $$ or $$ D\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $$ , is performed with a data sample corresponding to an integrated luminosity of 5.8 fb − 1 , collected during 2024 by the upgraded LHCb experiment. CP violation is observed through a difference in the distributions of the Dalitz plot of the D decay between the B + and B − mesons. The CKM angle γ is determined to be γ = (68 . 1 ± 6 . 7) ° . Other parameters related to the examined B meson decay modes are also measured. This is the first measurement of the CKM angle γ using the upgraded LHCb detector.- 5 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Open AccessMeasurement of γ using B± → DK± and B± → Dπ± decays with $ D\to {K}_{\mathrm{S}}^0{\pi}^{+}{\pi}^{-} $ and $ D\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $A bstract: A measurement of the CKM angle γ using the decay channels B ± → DK ± and B ± → Dπ ± , where the D meson decays to $$ D\to {K}_{\mathrm{S}}^0{\pi}^{+}{\pi}^{-} $$ or $$ D\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $$ , is performed with a data sample corresponding to an integrated luminosity of 5.8 fb − 1 , collected during 2024 by the upgraded LHCb experiment. CP violation is observed through a difference in the distributions of the Dalitz plot of the D decay between the B + and B − mesons. The CKM angle γ is determined to be γ = (68 . 1 ± 6 . 7) ° . Other parameters related to the examined B meson decay modes are also measured. This is the first measurement of the CKM angle γ using the upgraded LHCb detector. - Open Access
- 3 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Angular analysis of the B+ → π+μ+μ− decay
A bstract: This paper presents the first measurement of the forward-backward asymmetry, A FB , and the flat term, F H , that parameterise the angular distribution of the B + → π + μ + μ − decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb − 1 , collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the J/ψ and ψ (2 S ) narrow charmonium resonances. The Standard Model predictions lie within the obtained 68% confidence level interval in the high-mass and within the 99% interval in the low-mass region.
- 3 August 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (8)
Open AccessAngular analysis of the B+ → π+μ+μ− decay
A bstract: This paper presents the first measurement of the forward-backward asymmetry, A FB , and the flat term, F H , that parameterise the angular distribution of the B + → π + μ + μ − decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb − 1 , collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the J/ψ and ψ (2 S ) narrow charmonium resonances. The Standard Model predictions lie within the obtained 68% confidence level interval in the high-mass and within the 99% interval in the low-mass region.
- Open Access
- 29 July 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (7)
Machine learning techniques for jet reconstruction at LHCb and application to the search for $ H\to b\overline{b} $ and $ H\to c\overline{c} $ in $ \sqrt{s}=13 $ TeV pp collisionsA bstract: Two machine learning techniques for jet measurements at the LHCb experiment are presented: a regression-based method for jet-energy calibration and a deep neural network algorithm for jet flavour tagging, distinguishing between b -quark, c -quark, and light parton jets. These techniques are applied to a search for inclusive $$ H\to b\overline{b} $$ and $$ H\to c\overline{c} $$ decays using a LHCb dataset corresponding to an integrated luminosity of 1.6 fb − 1 . The observed (expected) 95% confidence level upper limits correspond to 6.6 (11.1) times the SM cross-section for the $$ H\to b\overline{b} $$ process, and 1003 (1834) times the SM cross-section for the $$ H\to c\overline{c} $$ process.- 29 July 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (7)
Open AccessMachine learning techniques for jet reconstruction at LHCb and application to the search for $ H\to b\overline{b} $ and $ H\to c\overline{c} $ in $ \sqrt{s}=13 $ TeV pp collisionsA bstract: Two machine learning techniques for jet measurements at the LHCb experiment are presented: a regression-based method for jet-energy calibration and a deep neural network algorithm for jet flavour tagging, distinguishing between b -quark, c -quark, and light parton jets. These techniques are applied to a search for inclusive $$ H\to b\overline{b} $$ and $$ H\to c\overline{c} $$ decays using a LHCb dataset corresponding to an integrated luminosity of 1.6 fb − 1 . The observed (expected) 95% confidence level upper limits correspond to 6.6 (11.1) times the SM cross-section for the $$ H\to b\overline{b} $$ process, and 1003 (1834) times the SM cross-section for the $$ H\to c\overline{c} $$ process.