Searching for long-lived particles at the LHC and beyond: Eighth workshop of the LHC LLP Community

Session

New ideas

19 Nov 2020, 14:00

Virtually, worldwide

Conveners

New ideas: 1

• James Beacham (Duke University (US))
• Carlos Vazquez Sierra (Nikhef National institute for subatomic physics (NL))

New ideas: 2

• James Beacham (Duke University (US))
• Carlos Vazquez Sierra (Nikhef National institute for subatomic physics (NL))

New ideas: 3

• Rebeca Gonzalez Suarez (Uppsala University (SE))
• Katherine Pachal (Duke University (US))

37. Exotic Higgs decays into displaced jets at the LHeC (12'+3')

Zeren Simon Wang (National Tsing Hua University)

19/11/2020, 14:00

Abstract: Profiling the Higgs boson requires the study of its non-standard decay modes. In this work we discuss the prospects of the Large Hadron electron Collider (LHeC) to detect scalar particles with masses >= 10 GeV produced from decays of the Standard Model (SM) Higgs boson. These scalar particles decay mainly to bottom pairs, and in a vast portion of the allowed parameter space they...

3. Probing Dark Matter with Disappearing Tracks at the LHC (12'+3')

Prof. Alexander Belyaev (University of Southampton & Rutherford Appleton Laboratory)

19/11/2020, 14:15

Models where dark matter is a part of an electroweak multiplet feature charged particles with macroscopic lifetimes due to the charged-neutral mass split of the order of pion mass. At the Large Hadron Collider, the ATLAS and CMS experiments will identify these charged particles as disappearing tracks, since they decay into a massive invisible dark matter candidate and a very soft charged...

5. Enhancing Sensitivities to Long-lived Particles with High Granularity Calorimeters at the LHC (12'+3')

Jia Liu (Peking University)

19/11/2020, 14:30

The search for long-lived particles (LLP) is an exciting physics opportunity in the upcoming runs of the Large Hadron Collider. In this paper, we focus on a new search strategy of using the High Granularity Calorimeter (HGCAL), part of the upgrade of the CMS detector, in such searches. In particular, we demonstrate that the high granularity of the calorimeter allows us to see ``shower tracks"...

10. New directions in BSM searches at FASER and beyond (12'+3')

Sebastian Trojanowski

19/11/2020, 14:45

A new far-forward physics program has recently been approved at the LHC to probe displaced decays of light and long-lived particles, as well as to study interactions of high-energy neutrinos in the FASER experiment. This also opens up a new direction in the LHC searches that could be continued in the longer time-scale during the HL-LHC phase. In this talk, we will focus on further BSM...

15. Extending the reach of FASER, MATHUSLA, and SHiP towards smaller lifetimes using secondary particle production (12'+3')

Krzysztof Jodlowski (National Centre for Nuclear Research)

19/11/2020, 15:20

Many existing or proposed intensity-frontier search experiments look for decay signatures of light long-lived particles (LLPs), highly displaced from the interaction point. This approach is, however, limited to new particles with decay lengths similar to or larger than the baseline of those experiments. We will discuss how this basic constraint can be overcome in BSM models that go beyond the...

38. R-parity Violation and Light Neutralinos at ANUBIS and MAPP (12'+3')

Julian Günther

19/11/2020, 15:35

n R-parity-violating supersymmetry the lightest neutralino can be very light, even massless. For masses in the range 500 MeV to 4.5 GeV the neutralino can be produced in hadron collisions from rare meson decays via an R-parity violating coupling, and subsequently decay to a lighter meson and a charged lepton. Due to the small neutralino mass and for small R-parity violating coupling the...

12. Probing the long lived heavy neutrinos at the colliders (12'+3')

Arindam Das (Osaka University)

19/11/2020, 15:50

The neutrino oscillation experiment has clearly pointed out that the Standard Model neutrinos have tiny masses and their flavors are mixed. There are a plenty of models which explain the mechanism of the generation of the neutrino mass. In this talk we will discuss about the simple neutrino mass generation process at the TeV scale which is often called the seesaw mechanism and its...

2. Long-lived Sterile Neutrinos at the LHC in Effective Field Theory (12'+3')

Mr Guanghui Zhou (University of Massachusetts Amherst)

19/11/2020, 16:05

We study the prospects of a displaced-vertex search of sterile neutrinos at the Large Hadron Collider (LHC) in the framework of the neutrino-extended Standard Model Effective Field Theory. The production and decay of sterile neutrinos can proceed via the standard active-sterile neutrino mixing in the weak current, as well as through higher-dimensional operators arising from decoupled new...

1. Fast convolutional neural networks for identifying long-lived particles in a high-granularity calorimeter (12'+3')

Juliette Alimena (CERN)

19/11/2020, 16:20

We present a first proof of concept to directly use neural network based pattern recognition to trigger on distinct calorimeter signatures from displaced particles, such as those that arise from the decays of exotic long-lived particles. The study is performed for a high granularity forward calorimeter similar to the planned high granularity calorimeter for the high luminosity upgrade of the...

16. Dark Pion Searches at Colliders and High Intensities (12'+3')

LINGFENG LI (HKUST)

19/11/2020, 16:35

We plan to study the phenomenology and experimental searches of the dark pions, which are the lightest hadrons in a hidden sector confining gauge theory. Such a scenario arises in many extensions of the Standard Model (SM). We consider that the leading interactions between the light hidden sector quarks and the SM particles come from the mixing of the light hidden quarks with heavy electroweak...

13. A new trigger for hadronic showers in the CMS muon system sensitive to particles with large lifetimes (12'+3')

Sven Dildick (Rice University (US))

19/11/2020, 16:50

Long-lived particles are predicted in many extensions beyond the standard model. They often have unique signatures in the detector. A particularly interesting model considers long-lived particles decaying hadronically just in front of or inside the CMS muon system. These particles are capable of producing large shower of hits in the muon chambers. Due to bandwidth limitations the current muon...

44. Uniting low-scale leptogeneses (12'+3')

Juraj Klaric (EPFL - Ecole Polytechnique Federale Lausanne (CH))

19/11/2020, 17:05

In this talk we will demonstrate that what was previously considered as different mechanisms of baryon asymmetry generation involving two right-handed Majorana neutrinos with masses far below the GUT scale -- leptogenesis via neutrino oscillations and resonant leptogenesis -- are actually united. We show that the observed baryon asymmetry can be generated for all experimentally allowed values...

6. Identifying the Origin of Long-Lived Particles with MATHUSLA and CMS (12'+3')

Jared Barron (University of Toronto)

19/11/2020, 17:40

MATHUSLA is a proposed large-volume displaced vertex (DV) detector, situated on the surface above CMS and designed to search for long-lived particles (LLPs) produced at the HL-LHC. We show that a discovery of LLPs at MATHUSLA would not only prove the existence of BSM physics, it would also uncover the theoretical origin of the LLPs, despite the fact that MATHUSLA gathers no energy or momentum...

4. Probing the High-Quality QCD Axion (12'+3')

Soubhik Kumar (University of Maryland)

19/11/2020, 17:55

Motivated by the Strong CP and the Axion Quality problem, I will consider heavier variants of the QCD axion which has a large and uncharted parameter space where it is long-lived. By focusing on the defining axionic coupling to gluons, I will evaluate the prospect of discovery of GeV-scale axions at the HL-LHC relying on the CMS track trigger upgrade. I will also comment on vetoing possible...

7. LLP and multi-lepton signatures from neutrino mass models (12'+3')

Dr juan carlos Helo (Universidad de La Serena)

19/11/2020, 18:10

We will discuss multi-lepton signals of LNV that can arise with experimentally interesting rates in certain loop models of neutrino mass generation. Interestingly, in such models the observed smallness of the active neutrino masses, together with the high-multiplicity of the final states, leads in large parts of the viable parameter space to the prediction of long-lived charged particles. We...

8. Searching for Bino-Stop Coannihilation Region in Open Data with Displaced Tracks (12'+3')

Haipeng An (Tsinghua University)

19/11/2020, 18:25

Light top quark superpartners are the key ingredients for supersymmetric models to solve the electroweak hierarchy problem. The compressed region of the parameter space that $m_{\tilde t_1} \approx m_{\chi^0_1}$ is notoriously difficult to search. In this region, if the LSP neutralino is pure bino, $\tilde t_1$ can be long-lived, which produces displaced vertices in detectors. We propose to...

9. Charming ALPs (12'+3')

Christiane Scherb (Universität Mainz)

19/11/2020, 18:40

We explore the phenomenology of a pseudo-Nambu-Goldstone bosons of a spontaneous broken global U(1) symmetry, axion-like particles (ALPs), with flavour violating couplings to up-quarks and vanishing couplings to down-quarks and leptons. Such a scenario is motivated by a confining ‘dark QCD’ UV completion. For light ALPs the phenomenology is governed by the couplings to charm- and up-quarks....

40. Detecting signatures of heavy displaced with input hit-level features (12'+3')

Kim Albertsson

19/11/2020, 18:55

Long-lived massive particles, predicted in numerous Standard Model extensions, are a particularly difficult target for online event reconstruction. This work presents a study of detecting signatures of heavy displaced vertices in a collider experiment based on input hit-level features. Preliminary results from the classification of events of a benchmark supersymmetric signal will be presented...