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Name

Jessica Prisciandaro

Position

Former member
Member from January 2018 to December 2020

Research statement

Experimentalist working on the CMS experiment at CERN. Current activities are a) search for long-lived Heavy Neutral Leptons, b) search for long-lived massive charged particles (HSCP), and c) silicon tracker calibration and operation

Projects

Research directions:

Data analysis in HEP, astroparticle and GW experiments
Detector commissioning, operation and data processing

Experiments and collaborations:

CMS

Active projects

CMS Tracker commissioning and performance assessment

Christophe Delaere

The CMS silicon strip tracker is the largest device of its type ever built. There are 24244 single-sided micro-strip sensors covering an active area of 198m2.
Physics performance of the detector are being constantly assessed and optimized as new data comes.
Members of UCL are playing a major role in the understanding of the silicon strip tracker and in the maintenance and development of the local reconstruction code.

External collaborators: CMS tracker collaboration.

Non-active projects

Particle Identification with ionization energy loss in the CMS experiment at the LHC

Giacomo Bruno

The CMS detector at the LHC can be used to identify particles via the measurement of their ionization energy loss. The sub-detectors that have provided so far useful information for this experimental technique are the silicon strip tracker and the pixel detectors. Identification of low momentum hadrons and detection of new exotic massive long-lived charged particles have all benefited from this experimental method. Members of UCL pioneered this technique in the early LHC times and have been developing the tools for its use and calibration. Since 2010 particle identification with ionization energy loss has been the basis of the CMS inclusive search for new massive long-lived charged particles, which has been providing the most stringent and model-independent limits existing to date on any model of new physics predicting such particles.

External collaborators: CMS collaboration.

Search for long-lived heavy neutral leptons with CMS

Giacomo Bruno

Many well motivated new physics extensions of the SM include new particles whose decay width is very small and hence have a decay length which is macroscopic. One very attractive and minimal extension of the standard model is one with right-handed neutrinos with Majorana masses below the electroweak scale (low scale see-saw). This addition is able to generate both the light neutrino masses and the baryon asymmetry of the universe via low scale leptogenesis. In what is probably the most studied model that invokes the low scale seesaw, the Neutrino Minimal Standard Model [2], one of the three right-handed neutrinos is a dark matter candidate. A large allowed region of phase space for right handed neutrinos spans masses between 1 and 50 GeV with corresponding lifetimes (cτ) ranging from 10^3 to 10^-4 m. For higher masses the right handed neutrino basically decays promptly and for lower masses the probability that it decays within the detector volume is virtually zero thus giving rise to missing transverse momentum in the detector. These latter two extreme cases can be captured experimentally by standard searches at the general purpose LHC experiments, while the intermediate case is the natural target of the so-called “displaced” searches, which are highly peculiar and challenging analyses at the LHC in high demand for dedicated data reconstruction tools in order to extend their sensitivity. We intend to search for long-lived sterile neutrinos decaying at displaced vertices into a charged light lepton and hadrons. A fundamental ingredient of this search is the identification of charged tracks emerging from highly displaced vertices.

Search for massive long-lived charged particles with the CMS detector at the LHC

Giacomo Bruno

The CMS detector at the LHC is used to search for yet unobserved heavy (mass >100 GeV/c$^2$), long-lived (lifetime > 1 ns), electrically charged particles, called generically HSCPs.
HSCPs can be distinguished from Standard Model particles by exploiting their unique signature: very high momentum and low velocity. These features are a consequence of their high mass and the relatively limited LHC collision energy. Two experimental techniques are used to identify such hypothetical heavy and low-velocity particles: the measurement of the ionization energy loss rate using the all-silicon tracker detector and the time-of-flight measurement with the muon detectors.

UCL members have developed the ionization energy loss identification technique and have lead the CMS HSCP search since 2010, when the first HSCP paper became one of the first published LHC search papers. Updated results, using the 2011 dataset, were then published followed by a comprehensive paper including also searches for fractional and multiply-charged particles published using the full CMS Run-1 dataset. The results obtained by analysing the 2015 Run 2 data at 13 TeV have also been published.

The analysis, which is very inclusive, doesn't find evidence of HSCP. It currently excludes, among various models, the existence of quasi-stable gluinos, predicted by certain realizations of supersymmetry, and Drell-Yan-produced staus with masses lower than about 1.3 TeV and 350 GeV, respectively. These and the other limits set by the analysis are the most stringent to date. The CMS HSCP papers total to date more than 300 citations.

Publications in IRMP

All my publications on Inspire

Number of publications as IRMP member: 3

2022

CP3-22-38: Strategies and performance of the CMS silicon tracker alignment during LHC Run~2

Tumasyan, Armen and others

[Abstract] [PDF] [Local file] [Journal] [Dial] [Full text]
Published in Nucl. Instrum. Meth. A
Refereed paper. August 12.

2020

CP3-20-40: Search for nonresonant Higgs boson pair production in the 4 leptons plus 2 b jets final state in proton-proton collisions at √s = 13 TeV

CMS Collaboration

[Full text]
Public experimental note. August 2.

2019

CP3-19-10: Searching for Long-Lived Particles beyond the Standard Model at the Large Hadron Collider

Alimena, Juliette and others

[Abstract] [PDF] [Journal] [Dial]
"White paper" of the LLP community.
Refereed paper. March 12.