From 4510d7ac30f830f1f3ecff0d09b2e9bea3dac416 Mon Sep 17 00:00:00 2001 From: Rocky Bala Garg Date: Mon, 9 Feb 2026 12:01:53 -0800 Subject: [PATCH 1/5] Create VertexingResolution.yml --- projects/VertexingResolution.yml | 43 ++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 projects/VertexingResolution.yml diff --git a/projects/VertexingResolution.yml b/projects/VertexingResolution.yml new file mode 100644 index 0000000..5d68e6e --- /dev/null +++ b/projects/VertexingResolution.yml @@ -0,0 +1,43 @@ +--- +name: Overcoming Vertex Reconstruction Limitations under the High-Density HL-LHC Pileup Environment +postdate: 2026-02-09 +categories: + - Tracking/Vertexing +durations: + - 3 months + - 6 months +experiments: + - LHC/HL-LHC/ACTS +skillset: + - Python + - C++ +status: + - Available +project: + - IRIS-HEP +location: + - Any +commitment: + - Full time +program: + - IRIS-HEP fellow +shortdescription: Overcoming Vertex Reconstruction Limitations under the High-Density HL-LHC Pileup Environment +description: > + Current vertex reconstruction algorithms at the LHC show a significant loss of efficiency in high-density environments + when the longitudinal separation between vertices falls below ~0.5 mm. The origin of this inefficiency is not well + understood. Given a typical vertex position resolution of ~50 μm, vertices separated by more than ~150 μm (~3σ) should, + in principle, be cleanly reconstructible. The observed performance degradation, therefore, points to limitations in the + reconstruction algorithms rather than to intrinsic detector resolution. + This project aims to identify the root cause of this inefficiency and to develop an improved vertex reconstruction strategy + suitable for the high-pileup conditions expected at the High-Luminosity LHC. The first phase will perform a detailed + characterization of vertex reconstruction performance for nearby vertices as a function of their separation, with a particular + focus on events in which one of two close-by vertices fails to be reconstructed. This will include detailed event displays + and a step-by-step analysis of the vertex seeding and reconstruction chain in failure cases, in order to pinpoint the + algorithmic features responsible for inefficiency in resolving close-by vertices separated by more than 3σ from each other. + In the second phase, the insights gained from this study will be used to design and implement targeted algorithmic improvements, + with the goal of significantly enhancing vertex reconstruction efficiency in high-density pileup environments at the HL-LHC. +contacts: + - name: Ariel Schwartzman + email: sch.slac.stanford@gmail.com + - name: Rocky Bala Garg + email: rbgarg@stanford.edu From f21f9fd804cf5f062e425b4008975d463d0d01a0 Mon Sep 17 00:00:00 2001 From: "pre-commit-ci[bot]" <66853113+pre-commit-ci[bot]@users.noreply.github.com> Date: Mon, 9 Feb 2026 20:02:19 +0000 Subject: [PATCH 2/5] [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --- projects/VertexingResolution.yml | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/projects/VertexingResolution.yml b/projects/VertexingResolution.yml index 5d68e6e..b6707c8 100644 --- a/projects/VertexingResolution.yml +++ b/projects/VertexingResolution.yml @@ -24,18 +24,18 @@ program: shortdescription: Overcoming Vertex Reconstruction Limitations under the High-Density HL-LHC Pileup Environment description: > Current vertex reconstruction algorithms at the LHC show a significant loss of efficiency in high-density environments - when the longitudinal separation between vertices falls below ~0.5 mm. The origin of this inefficiency is not well - understood. Given a typical vertex position resolution of ~50 μm, vertices separated by more than ~150 μm (~3σ) should, - in principle, be cleanly reconstructible. The observed performance degradation, therefore, points to limitations in the + when the longitudinal separation between vertices falls below ~0.5 mm. The origin of this inefficiency is not well + understood. Given a typical vertex position resolution of ~50 μm, vertices separated by more than ~150 μm (~3σ) should, + in principle, be cleanly reconstructible. The observed performance degradation, therefore, points to limitations in the reconstruction algorithms rather than to intrinsic detector resolution. - This project aims to identify the root cause of this inefficiency and to develop an improved vertex reconstruction strategy - suitable for the high-pileup conditions expected at the High-Luminosity LHC. The first phase will perform a detailed - characterization of vertex reconstruction performance for nearby vertices as a function of their separation, with a particular - focus on events in which one of two close-by vertices fails to be reconstructed. This will include detailed event displays - and a step-by-step analysis of the vertex seeding and reconstruction chain in failure cases, in order to pinpoint the - algorithmic features responsible for inefficiency in resolving close-by vertices separated by more than 3σ from each other. - In the second phase, the insights gained from this study will be used to design and implement targeted algorithmic improvements, - with the goal of significantly enhancing vertex reconstruction efficiency in high-density pileup environments at the HL-LHC. + This project aims to identify the root cause of this inefficiency and to develop an improved vertex reconstruction strategy + suitable for the high-pileup conditions expected at the High-Luminosity LHC. The first phase will perform a detailed + characterization of vertex reconstruction performance for nearby vertices as a function of their separation, with a particular + focus on events in which one of two close-by vertices fails to be reconstructed. This will include detailed event displays + and a step-by-step analysis of the vertex seeding and reconstruction chain in failure cases, in order to pinpoint the + algorithmic features responsible for inefficiency in resolving close-by vertices separated by more than 3σ from each other. + In the second phase, the insights gained from this study will be used to design and implement targeted algorithmic improvements, + with the goal of significantly enhancing vertex reconstruction efficiency in high-density pileup environments at the HL-LHC. contacts: - name: Ariel Schwartzman email: sch.slac.stanford@gmail.com From fc96ac9c02a6f996bbe7d6157cf4061ad5a5b35f Mon Sep 17 00:00:00 2001 From: Rocky Bala Garg Date: Wed, 11 Feb 2026 14:45:09 -0800 Subject: [PATCH 3/5] Update VertexingResolution.yml --- projects/VertexingResolution.yml | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/projects/VertexingResolution.yml b/projects/VertexingResolution.yml index b6707c8..2c94931 100644 --- a/projects/VertexingResolution.yml +++ b/projects/VertexingResolution.yml @@ -7,7 +7,9 @@ durations: - 3 months - 6 months experiments: - - LHC/HL-LHC/ACTS + - LHC + - HL-LHC + - ACTS skillset: - Python - C++ From 5e94fb94057f7574cdc5041b54c405f4a99bd24a Mon Sep 17 00:00:00 2001 From: David Lange Date: Mon, 2 Mar 2026 10:55:52 +0100 Subject: [PATCH 4/5] Fix HL-LHC to HLLHC in VertexingResolution.yml --- projects/VertexingResolution.yml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/projects/VertexingResolution.yml b/projects/VertexingResolution.yml index 2c94931..bf7b24a 100644 --- a/projects/VertexingResolution.yml +++ b/projects/VertexingResolution.yml @@ -8,7 +8,7 @@ durations: - 6 months experiments: - LHC - - HL-LHC + - HLLHC - ACTS skillset: - Python From 0ea66e4daa5f9f52637c9bb48ae325c1fea0bd14 Mon Sep 17 00:00:00 2001 From: David Lange Date: Mon, 2 Mar 2026 11:00:20 +0100 Subject: [PATCH 5/5] Update experiments list in VertexingResolution.yml --- projects/VertexingResolution.yml | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/projects/VertexingResolution.yml b/projects/VertexingResolution.yml index bf7b24a..3cb2a92 100644 --- a/projects/VertexingResolution.yml +++ b/projects/VertexingResolution.yml @@ -7,7 +7,8 @@ durations: - 3 months - 6 months experiments: - - LHC + - CMS + - ATLAS - HLLHC - ACTS skillset: