A search for rare B→ Dμ+ μ− decays

Journal of Instrumentation

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using ???????? collision data at

arXiv preprint arXiv:2404.19510

The four decays, , are observed for the first time using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of , corresponding to an integrated luminosity of . By considering the decay as reference channel, the following branching fraction ratios are measured to be, $$\frac{\cal{B} (\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} \rm{D}^{-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Lambda_c^{+} \rm \overline{D}^0 {K}^{-})} = {0.282}\pm{0.016}\pm{0.016}\pm{0.005}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} \rm {D}^{-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm {D}^{-} {K}^{-})} = {0.460}\pm{0.052}\pm{0.028}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} \rm {D}^{*-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm {D}^{-} {K}^{-})} = {2.261}\pm{0.202}\pm{0.129}\pm{0.046}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} \rm D^{*-} K^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm D^{-} K^{-})} = {0.896}\pm{0.137}\pm{0.066}\pm{0.018},$$ where the first uncertainties are statistical, the second are systematic, and the third are due to uncertainties in the branching fractions of intermediate particle decays. These initial observations mark the beginning of pentaquark searches in these modes, with more data set to become available following the LHCb upgrade.

arXiv preprint arXiv:2310.12278

The production rate of baryons relative to mesons in collisions at a center-of-mass energy TeV is measured by the LHCb experiment. The ratio of to production cross-sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the value measured in collisions, and increases by a factor of with increasing multiplicity. At relatively low transverse momentum, the ratio of to cross-sections is higher than what is measured in collisions, but converges with the ratio as the momentum increases. These results imply that the evolution of heavy quarks into final-state hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with a statistical hadronization model and implications for the mechanisms enforcing quark confinement are discussed.

Physical Review C

The production of η and η′ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.02 and 13 TeV and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16 TeV. The studies are performed in center-of-mass (cm) rapidity regions 2.5< y c. m.< 3.5 (forward rapidity) and− 4.0< y c. m.<− 3.0 (backward rapidity) defined relative to the proton beam direction. The η and η′ production cross sections are measured differentially as a function of transverse momentum for 1.5< p T< 10 GeV and 3< p T< 10 GeV, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for η and η′ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of η …

Journal of High Energy Physics

A measurement of CP-violating observables in B±→ D* K±and B±→ D* π±decays is made where the photon or neutral pion from the D*→ Dγ or D*→ Dπ 0 decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D→ π+ π− or D→ K+ K−. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb− 1. The B±→ D* K±and B±→ D* π±CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle γ, resulting in a measurement of γ=(). The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.

Physical Review Letters

A measurement of time-dependent CP violation in the decays of B 0 and B 0 mesons to the final states J/ψ (→ μ+ μ−) K S 0, ψ (2S)(→ μ+ μ−) K S 0 and J/ψ (→ e+ e−) K S 0 with K S 0→ π+ π− is presented. The data correspond to an integrated luminosity of 6 fb− 1 collected at a center-of-mass energy of√ s= 13 TeV with the LHCb detector. The CP-violation parameters are measured to be S ψK S 0= 0.717±0.013 (stat)±0.008 (syst) and C ψK S 0= 0.008±0.012 (stat)±0.003 (syst). This measurement of S ψK S 0 represents the most precise single measurement of the CKM angle β to date and is more precise than the current world average. In addition, measurements of the CP-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed.

Journal of Instrumentation

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using ???????? collision data at

Physical review letters

The decay-time-dependent C P asymmetry in B s 0→ J/ψ (→ μ+ μ−) K+ K− decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 6 fb− 1, collected with the LHCb detector at a center-of-mass energy of 13 TeV. Using a sample of approximately 349 000 B s 0 signal decays with an invariant K+ K− mass in the vicinity of the ϕ (1020) resonance, the C P-violating phase ϕ s is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B s 0− Bs 0 system, Δ Γ s, and the difference of the average B s 0 and B 0 meson decay widths, Γ s− Γ d. The values obtained are ϕ s=− 0.039±0.022±0.006 rad, Δ Γ s= 0.0845±0.0044±0.0024 ps− 1, and Γ s− Γ d=− 0.05 6− 0.0015+ 0.0013±0.0014 ps− 1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements to date and are consistent with …

arXiv preprint arXiv:1612.08110

A search for the charmless decay is performed using collision data collected by the LHCb experiment at centre-of-mass energies of and TeV, corresponding to an integrated luminosity of 3 fb. No signal is observed and upper limits on the branching fraction are set to at and at confidence level.

JOURNAL OF HIGH ENERGY PHYSICS

Null, N., Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinén, F., Ackernley, T., et al.(2024). Study of Bc⁺→ χc π⁺ decays. JOURNAL OF HIGH ENERGY PHYSICS, 2024 (2)[10.1007/jhep02 (2024) 173].

European Physical Journal C

Hadrons are systems of quarks bound by the strong interaction, described at the fundamental level by quantum chromodynamics (QCD). The production and decay of hadrons involve the nonperturbative regime of QCD, making calculations challenging. Much progress has been made in recent years in experimental and theoretical studies of beauty mesons, with the aim of testing the Standard Model and

Physical review letters

The decay-time-dependent C P asymmetry in B s 0→ J/ψ (→ μ+ μ−) K+ K− decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 6 fb− 1, collected with the LHCb detector at a center-of-mass energy of 13 TeV. Using a sample of approximately 349 000 B s 0 signal decays with an invariant K+ K− mass in the vicinity of the ϕ (1020) resonance, the C P-violating phase ϕ s is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B s 0− Bs 0 system, Δ Γ s, and the difference of the average B s 0 and B 0 meson decay widths, Γ s− Γ d. The values obtained are ϕ s=− 0.039±0.022±0.006 rad, Δ Γ s= 0.0845±0.0044±0.0024 ps− 1, and Γ s− Γ d=− 0.05 6− 0.0015+ 0.0013±0.0014 ps− 1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements to date and are consistent with …

arXiv preprint arXiv:2401.07564

In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.

Journal of High Energy Physics

A measurement of CP-violating observables in B±→ D* K±and B±→ D* π±decays is made where the photon or neutral pion from the D*→ Dγ or D*→ Dπ 0 decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D→ π+ π− or D→ K+ K−. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb− 1. The B±→ D* K±and B±→ D* π±CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle γ, resulting in a measurement of γ=(). The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.

arXiv preprint arXiv:2402.01336

Measurements of the branching fraction ratio with and decays, denoted and , are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 of collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the and decay modes. The combination of the results yields The result is compatible with previous measurements of the branching fractions and predictions based on the Standard Model.

Physical review letters

A measurement of time-dependent C P violation in the decays of B 0 and B 0 mesons to the final states J/ψ (→ μ+ μ−) K S 0, ψ (2 S)(→ μ+ μ−) K S 0 and J/ψ (→ e+ e−) K S 0 with K S 0→ π+ π− is presented. The data correspond to an integrated luminosity of 6 fb− 1 collected at a center-of-mass energy of s= 13 TeV with the LHCb detector. The C P-violation parameters are measured to be S ψ K S 0= 0.717±0.013 (stat)±0.008 (syst) and C ψ K S 0= 0.008±0.012 (stat)±0.003 (syst). This measurement of S ψ K S 0 represents the most precise single measurement of the CKM angle β to date and is more precise than the current world average. In addition, measurements of the C P-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed.

arXiv preprint arXiv:2402.05523

The first observation of the decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9fb, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the channel is measured to be $$ \frac{ {\cal{B}}( B_c^+ \to J/\psi \pi^+\pi^0 ) } { {\cal{B}}( B_c^+ \to J/\psi \pi^+ ) } = 2.80 \pm 0.15 \pm 0.11 \pm 0.16 \,, $$ where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for and decays, which are used to determine the detection efficiency. The mass spectrum is found to be consistent with the dominance of an intermediate contribution in accordance with a model based on QCD factorisation.

Journal of High Energy Physics

The production of ψ (2S) mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of= 8. 16 TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb− 1. The prompt and nonprompt ψ (2S) production cross-sections and the ratio of the ψ (2S) to J/ψ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt ψ (2S) is observed to be more suppressed compared to pp collisions than the prompt J/ψ production, while the nonprompt productions have similar suppression factors.

arXiv preprint arXiv:2402.14975

The LHCb collaboration measures production of the exotic hadron (3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state (2) suggests that the exotic (3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify (3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.

The first observation of the B+ c→ J/ψπ+ π0 decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb− 1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV. The ratio of its branching fraction relative to the B+ c→ J/ψπ+ channel is measured to be

Journal of High Energy Physics

Differential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to final states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at= 13 TeV and with an integrated luminosity of 140 fb− 1. The data are corrected for the effects of detector inefficiency and resolution and are compared to state-of-the-art Monte Carlo event generator predictions. The differential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model effective field theory.

Journal of High Energy Physics

A search for nonresonant Higgs boson pair production in the final state is performed using 140 fb− 1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier κ λ but also of the quartic HHVV (V= W, Z) coupling modifier κ 2V. No significant excess above the expected background from Standard Model processes is observed. An observed upper limit μ HH< 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are− 1.4< κ λ< 6.9 and− 0.5< κ 2V< 2.7, assuming …

Journal of High Energy Physics

A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139 fb− 1 of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired final states. A single control region is used to constrain the normalisation of the WZ+ jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models …

Journal of High Energy Physics

Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb− 1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and …

Journal of high energy physics

This paper presents a measurement of the production cross-section of a boson in association with - or -jets, in proton-proton collisions at TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 140 fb. Inclusive and differential cross-sections are measured for events containing a boson decaying into electrons or muons and produced in association with at least one -jet, at least one -jet, or at least two -jets with transverse momentum GeV and rapidity . Predictions from several Monte Carlo generators based on next-to-leading-order matrix elements interfaced with a parton-shower simulation, with different choices of flavour schemes for initial-state partons, are compared with the measured cross-sections. The results are also compared with novel predictions, based on infrared and collinear safe jet flavour dressing algorithms. Selected -jet observables, optimized for sensitivity to intrinsic-charm, are compared with benchmark models with different intrinsic-charm fractions.

Journal of High Energy Physics

New GeV-scale dark forces coupling predominantly to quarks offer novel signatures that can be produced directly and searched for at high-luminosity colliders. We compute the photon-proton and electron-proton cross sections for producing a GeV-scale gauge boson arising from a U (1) B gauge symmetry. Our calculation relies on vector meson dominance and a phenomenological model for diffractive scattering used for vector-meson photoproduction. The parameters of our phenomenological model are fixed by performing a Markov Chain Monte Carlo fit to existing exclusive photoproduction data for ω and ϕ mesons. Our approach can be generalized to other GeV-scale dark gauge forces.

Journal of high energy physics

Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum in the range 8<< 15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial-and final-state radiation. The relative transverse activity classifier,, is used to group events according to their UE activity, where is the charged-particle multiplicity per event in the transverse region and is the mean …

Journal of High Energy Physics

We explain how equivariant localization may be applied to AdS/CFT to compute various BPS observables in gravity, such as central charges and conformal dimensions of chiral primary operators, without solving the supergravity equations. The key ingredient is that supersymmetric AdS solutions with an R-symmetry are equipped with a set of equivariantly closed forms. These may in turn be used to impose flux quantization and compute observables for supergravity solutions, using only topological information and the Berline-Vergne-Atiyah-Bott fixed point formula. We illustrate the formalism by considering AdS 5× M 6 and AdS 3× M 8 solutions of D= 11 supergravity. As well as recovering results for many classes of well-known supergravity solutions, without using any knowledge of their explicit form, we also compute central charges for which explicit supergravity solutions have not been constructed.

Journal of High Energy Physics

Differential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to final states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at= 13 TeV and with an integrated luminosity of 140 fb− 1. The data are corrected for the effects of detector inefficiency and resolution and are compared to state-of-the-art Monte Carlo event generator predictions. The differential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model effective field theory.

Journal of High Energy Physics

A search for nonresonant Higgs boson pair production in the final state is performed using 140 fb− 1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier κ λ but also of the quartic HHVV (V= W, Z) coupling modifier κ 2V. No significant excess above the expected background from Standard Model processes is observed. An observed upper limit μ HH< 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are− 1.4< κ λ< 6.9 and− 0.5< κ 2V< 2.7, assuming …

Journal of High Energy Physics

A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139 fb− 1 of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired final states. A single control region is used to constrain the normalisation of the WZ+ jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models …

Journal of high energy physics

Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum in the range 8<< 15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial-and final-state radiation. The relative transverse activity classifier,, is used to group events according to their UE activity, where is the charged-particle multiplicity per event in the transverse region and is the mean …

Journal of High Energy Physics

Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb− 1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and …

Journal of high energy physics

This paper presents a measurement of the production cross-section of a boson in association with - or -jets, in proton-proton collisions at TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 140 fb. Inclusive and differential cross-sections are measured for events containing a boson decaying into electrons or muons and produced in association with at least one -jet, at least one -jet, or at least two -jets with transverse momentum GeV and rapidity . Predictions from several Monte Carlo generators based on next-to-leading-order matrix elements interfaced with a parton-shower simulation, with different choices of flavour schemes for initial-state partons, are compared with the measured cross-sections. The results are also compared with novel predictions, based on infrared and collinear safe jet flavour dressing algorithms. Selected -jet observables, optimized for sensitivity to intrinsic-charm, are compared with benchmark models with different intrinsic-charm fractions.

Journal of High Energy Physics

Differential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to final states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at= 13 TeV and with an integrated luminosity of 140 fb− 1. The data are corrected for the effects of detector inefficiency and resolution and are compared to state-of-the-art Monte Carlo event generator predictions. The differential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model effective field theory.

Journal of High Energy Physics

A search for nonresonant Higgs boson pair production in the final state is performed using 140 fb− 1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier κ λ but also of the quartic HHVV (V= W, Z) coupling modifier κ 2V. No significant excess above the expected background from Standard Model processes is observed. An observed upper limit μ HH< 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are− 1.4< κ λ< 6.9 and− 0.5< κ 2V< 2.7, assuming …

Journal of High Energy Physics

A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139 fb− 1 of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired final states. A single control region is used to constrain the normalisation of the WZ+ jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models …

Journal of High Energy Physics

Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb− 1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and …

Journal of high energy physics

This paper presents a measurement of the production cross-section of a boson in association with - or -jets, in proton-proton collisions at TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 140 fb. Inclusive and differential cross-sections are measured for events containing a boson decaying into electrons or muons and produced in association with at least one -jet, at least one -jet, or at least two -jets with transverse momentum GeV and rapidity . Predictions from several Monte Carlo generators based on next-to-leading-order matrix elements interfaced with a parton-shower simulation, with different choices of flavour schemes for initial-state partons, are compared with the measured cross-sections. The results are also compared with novel predictions, based on infrared and collinear safe jet flavour dressing algorithms. Selected -jet observables, optimized for sensitivity to intrinsic-charm, are compared with benchmark models with different intrinsic-charm fractions.

Journal of High Energy Physics

The flow of shape eigenmodes of the small fluctuation operator around BPS 2-vortex solutions is calculated, as a function of the intervortex separation 2d. For the rotationally-invariant 2-vortex, with d= 0, there are three discrete modes; the lowest is non-degenerate and the upper two are degenerate. As d increases, the degeneracy splits, with one eigenvalue increasing and entering the continuous spectrum, and the other decreasing and asymptotically coalescing with the lowest eigenvalue, where they jointly become the eigenvalue of the 1-vortex radial shape mode. The behaviour of the eigenvalues near d= 0 is clarified using a perturbative analysis, and also in light of the 2-vortex moduli space geometry.