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

19 Jun 2023, 12:00 → 23 Jun 2023, 20:20 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

James Beacham (Duke University (US))

https://cern.ch/longlivedparticles

-------------- LLP13 --------------

The thirteenth LLP Community workshop will occur from 19 to 23 June, 2023, at CERN.

It will take place in-person, for the first time in several years!

Please join us for the hottest-and-latest in LLPs around the globe.

Highlights:

-- CERN Colloquium by Jonathan Feng on Monday at 16:30 in the Main Auditorium, arranged in conjunction with our workshop:

https://indico.cern.ch/event/1288976/

-- Welcome reception Monday evening at 18:30

-- Workshop dinner at Luigia Academy on Tuesday at 19:00

-- Visits to MilliQan (LHC Point 5, near CMS) or LHCb / planned-CODEX-b (LHC Point 8) on Thursday morning

N.B.: The workshop is in fully plenary mode, including the working group / brainstorming sessions, but the room we're using varies from day to day and sometimes session to session. Make sure to double-check the location before each day begins.

N.B.B.: On Tuesday and Wednesday morning we will start the day with coffee and croissants at 9:30, i.e., we all meet for breakfast on those days.

Previous workshops can be found here.

Organizers:

Sai Neha Santpur
Audrey Kvam
Karri Folan Di Petrillo
Lisa Benato
Juliette Alimena
Nishita Desai
Andrii Usachov
Louis Henry
Mason Proffitt
Carlos Vazquez Sierra
Federico Leo Redi
Matthew Citron
José Francisco Zurita
Louie Corpe
James Beacham
Albert De Roeck

Booking form LLP Workshop 2023.docx

Booking form LLP Workshop 2023.pdf

Monday 19 June

1 Welcome and introduction

Speaker: James Beacham (Duke University (US))

Beacham_LLP13_Thirteenth_Community_Workshop_Intro_2023June19.pdf

Intro_GMT20230619-110829_Recording_1920x1080.mp4

Intro_GMT20230619-110829_Recording.cc.vtt

Intro_GMT20230619-110829_Recording.m4a

Intro_GMT20230619-110829_Recording.transcript.vtt

New LLP results from ATLAS and CMS

Conveners: Audrey Katherine Kvam (University of Massachusetts (US)), Lisa Benato (Hamburg University (DE))

ATLASCMS_GMT20230619-125352_Recording_1920x1080.mp4

ATLASCMS_GMT20230619-125352_Recording.cc.vtt

ATLASCMS_GMT20230619-125352_Recording.m4a

ATLASCMS_GMT20230619-125352_Recording.transcript.vtt

2 ATLAS: Displaced vertex with jets

Speaker: David Rousso (University of Cambridge (GB))

LLP Workshop DV Jets.pdf

3 CMS: Inelastic dark matter

Speaker: Andre Frankenthal (Princeton University (US))

Frankenthal_CMS_iDM_LLP13Workshop.pdf

4 ATLAS: Micro-displaced muons

Speaker: Melissa Yexley (University of London (GB))

myexley_ATLAS_microdisplacedmuons_13LLPworkshop.pdf

14:15 Coffee

New LLP results from ATLAS and CMS

Conveners: Audrey Katherine Kvam (University of Massachusetts (US)), Lisa Benato (Hamburg University (DE))

ATLASCMS_GMT20230619-125352_Recording_1920x1080.mp4

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ATLASCMS_GMT20230619-125352_Recording.transcript.vtt

5 ATLAS: Vertexing for non-prompt photons

Speaker: Devanshu Kiran Panchal (University of Texas at Austin (US))

dpanchal_LLP13_talk.pdf

6 CMS: Disappearing tracks

Speaker: Viktor Kutzner (Hamburg University (DE))

llp13-sus-21-006.pdf

7 ATLAS: Performance of the reconstruction of large impact parameter tracks in the inner detector of ATLAS

Speaker: Hamza Hanif (Simon Fraser University (CA))

lrt_llp_workshop.pdf

8 CMS: Long-lived HNLs with displaced jet tagger

Speaker: Haifa Rejeb Sfar (The State University of New York SUNY (US))

HSFAR_LLP13_workshop.pdf

9 Workshop photo

16:10 Break and transition

10 CERN Colloquium: Jonathan Feng — Long-Lived Particles and the Future of Particle Physics

We've organized a special CERN Colloquium by Jonathan Feng in conjunction with our LLP13 workshop. More detail can be found here: https://indico.cern.ch/event/1288976/

Speaker: Jonathan Lee Feng (University of California Irvine (US))

2306cerncolloquium.pdf

11 Welcome reception

Tuesday 20 June

09:30 Coffee and croissants

Working group session: Reinterpretations of LLP results: new trends

Conveners: Carlos Vazquez Sierra (Universidade de Santiago de Compostela (ES)), Dr Louie Corpe (Laboratoire de Physique de Clermont (LPC))

12 ATLAS dE/dX reinterpretation materials feedback (inc. discussion)

Speakers: Prof. Andre Lessa (CCNH - Univ. Federal do ABC), Dr Louie Corpe (Laboratoire de Physique de Clermont (LPC))

GMT20230620-080835_Recording_3348x1400.mp4

GMT20230620-080835_Recording.cc.vtt

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GMT20230620-080835_Recording.transcript.vtt

HSCP-Recast.pdf

13 ATLAS SimpleAnalysis for LLPs

Speaker: Yvonne Ng (Deutsches Elektronen-Synchrotron (DE))

SimpleAnalysis LLP talk.pdf

14 Long-lived particle phenomenology in the 2HDM+a model

Higgs decays displaced from the primary interaction vertex represent a striking experimental signature that is actively searched for by the ATLAS, CMS and LHCb collaborations. We point out that signals of this type naturally appear in the context of the 2HDM+$a$ model if the mixing angle $\theta$ of the two CP-odd weak spin-0 eigenstates is tiny and the dark matter (DM) sector is either decoupled or kinematically inaccessible. Utilising two suitable benchmark scenarios, we determine the constraints on the parameter space of the 2HDM+$a$ model that are set by the existing LHC searches for long-lived particles (LLPs) in Higgs decays. We find that depending on the precise mass spectrum of the spin-0 states, mixing angles $\theta$ in the ballpark of a few $10^{-8}$ to $10^{-5}$ can be excluded based on LHC Run II data. This finding emphasises the unique role that searches for displaced signatures can play in constraining the parameter space of the 2HDM+$a$ model. The ensuing DM phenomenology is also discussed. In particular, we show that parameter choices leading to an interesting LLP phenomenology can simultaneously explain the DM abundance observed in today's Universe in a natural way.

Speaker: Luc Schnell (Max Planck Institute for Physics)

2HDM+a LLP.pdf

15 Validation of reinterpretation material for ATLAS search for displaced hadronic jets

The ATLAS search for displaced hadronic jets in the calorimeters (arXiv:2203.01009) produced as part of its re-interpretation material, an efficiency map for selecting events in the signal region, which exploits only truth-level kinematic properties of the LLPs.

As part of a master's project, we have sought to validate this map by recovering the ATLAS results of efficiencies and constraint on the cross section of the benchmark Hidden Sector mode, as published in arXiv:2203.01009. Using samples generated with $MadGraph5\_aMC@NLO$, we have seen that the map is accurate in the high-lifetime regime, but breaks down at low lifetimes.

In this talk we will briefly describe the map and our checks of it. We will conclude on the possible improvement we can make and on the future of the project, and see in what extend it would be useful to have a recipe that comes with a benchmark LLP models used by ATLAS and CMS.

Speaker: Thomas Chehab

%0AValidation of reinterpretation material for ATLAS_ LLP_workshop.pdf

16 Discussion

12:05 Lunch

New ideas in LLP phenomenology: Session 1

Conveners: Audrey Kvam (University of Massachusetts (US)), Dr José Francisco Zurita (IFIC - Univ. of Valencia and CSIC (ES))

17 Measuring lepton number violation at colliders

The heavy neutrino Majorana mass term appearing in low-scale seesaw models violates lepton number. Therefore, heavy neutral leptons are not only characterised by their mass and coupling strength but also by the amount of lepton number violation they induce. I discuss the merits of different benchmark models for this scenario and present the potential to measure lepton number violation in long-lived heavy neutrino decays via heave neutrino-antineutrino oscillations.

Speaker: Jan Hajer (Universidade de Lisboa)

GMT20230620-110411_Recording_1832x982.mp4

GMT20230620-110411_Recording.m4a

GMT20230620-110411_RecordingnewChat.txt

GMT20230620-110411_Recording.transcript.vtt

Measuring lepton number violation at colliders

18 Reinterpretation of searches of LLPs from meson decays

This work presents a simple and quick method to reinterpret models predicting long-lived particles (LLPs) produced from meson decays. The proposed method avoids the need for Monte-Carlo simulations and the implementation of detector geometries and experimental cuts, significantly reducing the computation time of typical recasting and reinterpretation works. The only required inputs are theoretical, allowing calculation of the production and decay rates of the LLPs. The method assumes that the LLPs in the models arise from mesons with similar mass and lifetime and have a lab-frame decay length significantly larger than the distance between the interaction point and the detector. As an example, we use this method to reinterpret exclusion bounds on heavy neutral leptons (HNLs) in the minimal “3+1” scenario into those on HNLs within a general effective-field-theory framework and into axion-like particles. The results reproduce existing findings and obtain new exclusion bounds from past experimental data from CHARM and Belle.

Speaker: Rebeca Beltran (IFIC (CSIC-UV))

LLP13_Reinterpretation_Rebeca.pdf

19 Heavy neutral lepton searches in cosmic ray beam dump experiments

In this talk, we discuss the possibility of testing Heavy Neutral Leptons (HNLs) in "cosmic ray beam-dumps": setups where high-energy incident cosmic rays impinge on the Earth's atmosphere and then on the Earth's surface. We focus on HNL production from atmospherically produced parent meson decays and discuss these in the context of a possible explanation of the appearing Cherenkov showers observed by the SHALON Cherenkov telescope and the ultra-high energy anomalous events detected by the ANITA neutrino experiment. We then discuss two proposed experimental setups with improved sensitivities, namely a Cherenkov telescope pointing at a sub-horizontal angle and shielded by the mountain cliff at Mount Thor, and a geostationary satellite that observes a part of the Sahara desert. Our results show that the Mount Thor experiment can test hitherto unexplored HNL parameter space below the kaon mass; while the geostationary satellite experiment can significantly increase the HNL parameter space coverage in the mass range from 10 MeV to 2 GeV and test neutrino mixing $|U_{\alpha4}|^2$ down to $10 ^{-11}$ for masses around 300 MeV.

Speaker: Baibhab Pattnaik (IFIC (University of Valencia, CSIC))

HNL_CR

LLP13_HNL (1).pdf

20 Simplified framework for long-lived particles at neutrino facilities

Modern-day accelerator neutrino facilities are excellent venues for searches for new-physics particles. Many distinct new-physics models predict overlapping signatures and phenomenology in these experiments. In this work, we advocate for the adoption of simplified frameworks when studying these types of new-physics signatures, which are characterized by a small number of primary variables, including particle masses, lifetimes, and production and decay modes/rates that most directly control signal event rates and kinematics. In particular, taking the example of long-lived particles that decay inside a neutrino detector as a test case, we study formulate and study simplified frameworks in the context of light scalars/fermions produced in kaon decays which then decay into final states containing an electron-positron pair. We show that using these simplified frameworks can allow for individual experimental analyses to be applicable to a wide variety of specific model scenarios. As a side benefit, we demonstrate that using this approach can allow for the T2K collaboration, by reinterpreting its search for Heavy Neutral Leptons, to be capable of setting world-leading limits on the Higgs-Portal Scalar model. Furthermore, we argue the simplified framework interpretation can serve as a bridge to model identification in the hopeful detection of a new-physics signal. As an illustration, we perform a first determination of the likelihood that, in the presence of a new-physics signal in a detector like the DUNE ND-GAr, multiple different new-physics hypotheses (such as the Higgs-Portal Scalar and Heavy Neutral Lepton ones) can be disentangled. We demonstrate that this model discrimination is favorable for some portions of detectable new-physics parameter space but for others, it is more challenging.

Speaker: Wenjie Huang

LLPNu_Simplifield_Model.pdf

21 Emerging jet probes of exotic Higgs decays

A strongly interacting dark sector with long-lived dark mesons (lifetimes between few centimeters and few meters) can give rise to emerging jets, which have been sought by the CMS collaboration.

In this talk I would describe the validation of the CMS emerging jet search using the publicly available material. We will interpretate this search in the context of Exotic Higgs decays, setting relevant constraints to the branching fraction of a Higgs boson into two dark quarks.

Speaker: Juliana Carrasco (IFIC (UV-CSIC))

EJs_llpw.pdf

14:40 Coffee

New ideas in LLP phenomenology: Session 2

Conveners: Dr José Francisco Zurita (IFIC - Univ. of Valencia and CSIC (ES)), Mason Proffitt (University of Washington (US))

22 Updating bounds on R-parity-violating supersymmetry with a long-lived light bino

In supersymmetric models with R-parity-violation (RPV), light neutralinos with masses in the GeV-scale or below that are necessarily bino-like are still allowed by various constraints, as they decay via RPV couplings. These RPV couplings are in general constrained to be small, and hence such light binos, if produced e.g. at a beam-dump or collider experiment, appear as displaced vertices or missing energy at the detector level. The same signatures have been extensively searched for at various experiments, in the theoretical context of sterile neutrinos which mix with active neutrinos. In this work, we recast both past and present experiments' sensitivities to sterile neutrinos, and hence obtain new bounds on RPV couplings associated with a light bino. We find experiments such as FASER and Super-Kamiokande can exclude values of RPV couplings orders of magnitude stronger than the current bounds in several benchmark scenarios.

Speaker: Martin Schürmann

audio1586811691.m4a

LLP13 - HNL-Bino Recasting.pdf

recording.conf

Screenshot[1]-01.png

video1586811691.mp4

23 Long-lived ALPs in top final states

We investigate the discovery potential for long-lived particles produced in association with a top-antitop quark pair at the (High-Luminosity) LHC. Compared to inclusive searches for a displaced vertex, top-associated signals offer new trigger options and an extra handle to suppress background. We propose a search strategy for a displaced di-muon vertex decaying in the tracking chambers, calorimeters or muon chambers, in addition to a reconstructed top-antitop pair. Such a signature is predicted in many models with new light scalars or pseudo-scalars, which generically couple more strongly to top quarks than to light quarks. For axion-like particles with masses above the di-muon threshold and below the $b\bar{b}$ threshold, we find that the (High-Luminosity) LHC can probe effective top-quark couplings as small as $c_{tt}/f_a = 0.03~(0.01)~$TeV$^{-1}$ and proper decay lengths as long as $10~(400)$ m, with data corresponding to an integrated luminosity of 150 fb$^{-1}$ (3 ab$^{-1}$). In this talk I will present a summary of the analysis, including signal and background kinematics, the event selection, and predictions for LHC Run 2 and High-Luminosity LHC.

Speaker: Lovisa Rygaard (Deutsches Elektronen-Synchrotron (DE))

LLPworkshop-2.pdf

24 Light scalars at FASER

In this talk, I will show the prospect of detecting light CP-even and CP-odd scalars at FASER and FASER 2. Considering a model-independent framework describing the most general interactions between a CP-even or CP-odd scalar and SM particles using the notation of coupling modifiers in the effective Lagrangian, we develop the general formalism for scalar production and decay. We then analyze the FASER and FASER 2 reaches of light scalars in the large tanβ region of the Type-I two Higgs double model as a case study

Speaker: Wei Su (Sun Yat-sen University)

LLP_CERN_2023_WeiSu.pdf

25 Vectorlike leptons and long-lived bosons at the LHC

Long-lived particles are a prime target of searches in current and upcoming LHC runs. In my talk, I will discuss a renormalizable theory that includes a heavy weak- singlet vectorlike lepton that decays into a long-lived pseudoscalar boson and a tau lepton. I will show that this can be the dominant decay mode of the vectorlike lepton provided the pseudoscalar couplings deviate from the case of a Nambu-Goldstone boson. The electroweak production of vectorlike leptons leads to a rich phenomenol- ogy at colliders, including signals with many taus or photons. I will analyze in detail the case where the pseudoscalar has a decay length of a few meters and thus would typically deposit energy in the muon chambers of the CMS or ATLAS detectors.

Speaker: Elias Bernreuther (Fermilab)

llp13_vlls_llps.pdf

26 Plenary: Axions, ALPs, and LLPs

Zoom: https://cern.zoom.us/j/69803628929?pwd=bCtiYjVDdWtJUXNmZi9IRVIxUkJRZz09

Speaker: Prof. Martin Bauer (IPPP Durham)

GMT20230620-145544_Recording_1344x768.mp4

GMT20230620-145544_Recording.m4a

GMT20230620-145544_Recording.transcript.vtt

LLP 2023_MartinBauer.pdf

27 Workshop dinner at Luigia Academy

For those who will walk over, we propose to meet at R1 at 18:30 and walk over. It should be about a 10 minute walk through entrance C.

Wednesday 21 June

09:30 Coffee and croissants

Working group session: What would we do with 200 MCHF (or more) for LLPs, at the LHC and beyond?

Conveners: Albert De Roeck (CERN), Juliette Alimena (DESY)

28 discussion

Beacham_UV_Sky_Ideas_LLP13_2023June21.pdf

deroeck_LLP13_discussion_v1.pdf

deroeck_LLP13_discussion_v1.pdf

deroeck_LLP13_discussion_v1.pptx

GMT20230621-080902_Recording_1920x1080.mp4

GMT20230621-080902_Recording.m4a

GMT20230621-080902_RecordingnewChat.txt

GMT20230621-080902_Recording.transcript.vtt

live google doc

12:00 Lunch

Experimental LLP project panoply: Session 1

Conveners: Carlos Vazquez Sierra (Universidade de Santiago de Compostela (ES)), Sai Neha Santpur (Univ. of California Santa Barbara (US))

29 Update on the CODEX-b Experiment

The High Luminosity LHC will be a tremendous opportunity to search for long lived particles (LLPs) from an extended hidden/dark sector, feebly connected to the known SM sector. Such LLP searches will require special detectors, placed far away from the proton-proton collision point and shielded against SM backgrounds. The CODEX-b detector, to be placed behind a thick shielding wall inside the LHCb cavern, around 25m from the LHCb interaction point, provides a novel solution. On the journey to construction of the full detector, a demonstrator (CODEX-𝛽) is foreseen for installation and operation during LHC Run 3. This talk will present the latest developments and will focus on the status and plans for CODEX-𝛽.

Speaker: Titus Mombächer (CERN)

GMT20230621-113308_Recording_1920x1080.mp4

GMT20230621-113308_Recording.m4a

GMT20230621-113308_RecordingnewChat.txt

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LLP13_CODEXbeta_presentation.pdf

30 Update on the planned Forward Physics Facility

Speaker: Jamie Boyd (CERN)

FPF_LLP13_21.6.23.pdf

31 New physics searches using ProtoDUNE and the CERN SPS accelerator

Speaker: Laura Molina Bueno (Univ. of Valencia and CSIC (ES))

molina_LLP2023_21062023.pdf

32 New results for searches of exotic decays with NA62 in beam-dump mode

The NA62 experiment at CERN took data in 2016–2018 with the main goal of measuring the $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay. We report on the search for visible decays of exotic mediators from data taken in "beam-dump" mode with the NA62 experiment. The NA62 experiment can be run as a "beam-dump experiment" by removing the Kaon production target and moving the upstream collimators into a "closed" position. More than $10^{17}$ protons on target have been collected in this way during a week-long data-taking campaign by the NA62 experiment. We report on new results from analysis of this data, with a particular emphasis on Dark Photon and Axion-like particle Models.

Speaker: Alina Kleimenova (EPFL - Ecole Polytechnique Federale Lausanne (CH))

lhc_llp2023_na62_kleimenova.pdf

14:55 Coffee

Experimental LLP project panoply: Session 2

Conveners: Louis Henry (EPFL - Ecole Polytechnique Federale Lausanne (CH)), Matthew Daniel Citron (University of California Davis (US))

33 SHiP

Speaker: Oliver Lantwin (INFN Napoli)

GMT20230621-134700_Recording_1920x1080.mp4

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olantwin_230621.pdf

34 FLArE

Speaker: Matteo Vicenzi (INFN e Universita Genova (IT))

FLArE_LLP13Worshop_20230621.pdf

35 Probing new physics at the LUXE experiment

The proposed LUXE experiment (LASER Und XFEL Experiment) at DESY, Hamburg, using the electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the standard model. In this talk we show that by leveraging the large photon flux generated at LUXE, one can probe axion-like-particles (ALPs) up to a mass of 350 MeV and with photon coupling of 3×10−6 GeV−1. This reach is comparable to the background-free projection from NA62. In addition, we will discuss other probes of new physics such as ALPs-electron coupling.

Speaker: Ivo Schulthess (DESY)

LLP13_schulthessIvo_final.pdf

36 Searches for beyond the standard model physics with the ArgoNeuT Experiment

ArgoNeuT was a 0.24-ton Liquid Argon Time Projection Chamber (LArTPC) neutrino detector at Fermilab running from 2009 to 2010. It was located along the NuMI neutrino beam upstream of the MINOS near detector and collected six months of data in anti-neutrino beam mode. ArgoNeuT’s dataset has been used to perform numerous first neutrino cross-section measurements on argon. It can also be used to probe physics beyond the standard model resulting from high-energy proton fixed-target collisions in the NuMI beam. ArgoNeuT has recently performed searches for millicharged particles, tau-coupled heavy neutral leptons, and heavy QCD axions leveraging the unique capabilities of ArgoNeuT and the MINOS near detector. In each case these searches were the first of their kind in LArTPC neutrino detectors and resulted in leading constraints on the respective parameter spaces. This talk will present an overview of the results of each of these analyses and discuss prospects for future beyond the standard model searches with ArgoNeuT.

Speaker: Patrick Green (University of Oxford (GB))

ArgoNeuT_LLP_23.06.21.pdf

37 Semi-visible dark photons at the NA64 experiment

Beyond the minimal kinetically-mixed dark photon scenarios predicting fully visible and fully invisible mediator decays, next-to-minimal theories have been considered as compelling frameworks for thermal dark matter and some low-energy anomalies, as the muon g-2.
This talk will showcase the potential of the NA64 experiment in the exploration of rich dark sectors in which the dark photon is semi-visible. The NA64 invisible results have been re-interpreted in the context of two inelastic dark matter models to account for the different signal signature, entailing both missing energy and visible final states.

Speaker: Martina Mongillo (ETH Zurich (CH))

SemivisibleDP_NA64_Mongillo.pdf

Thursday 22 June

38 Visits to MilliQan or LHCb/CODEX-b

LLP13_visits.pdf

12:00 Lunch

Experimental LLP project panoply: Session 3

Conveners: Andrii Usachov (Nikhef National institute for subatomic physics (NL)), Sai Neha Santpur (Univ. of California Santa Barbara (US))

39 LLPs in MoEDAL-MAPP

The unprecedented collision energy of the LHC has opened up a new discovery regime. The first LHC dedicated search experiment, MoEDAL, has inaugurated the lifetime frontier being optimised for searches of long-lived particles. MoEDAL is designed to search highly ionising particle avatars of new physics using proton and heavy-ion collisions at the LHC. The upgrade for MoEDAL at Run 3 - the MAPP detector (MoEDAL Apparatus for Penetrating Particles) - will extend the physics reach to include feebly interacting, long-lived messengers of physics beyond the Standard Model. This will allow us to explore a number of models of new physics, including dark sector models, in a complementary way to that of the main LHC detectors. The presentation will focus on recent results and plans for the LHC Run 3.

Speaker: Dr Vasiliki Mitsou (Univ. of Valencia and CSIC (ES))

Mitsou-MoEDAL.pdf

40 Search for feebly-interacting particles with SND@LHC at CERN

SND@LHC is a compact experiment proposed to exploit the high flux of energetic neutrinos of all flavours from the LHC in a hitherto unexplored pseudo-rapidity region of 7.2 < 𝜂 < 8.4, complementary to all the other experiments at the LHC. The experiment is located 480 m downstream of IP1 in the unused TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target mass of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The configuration allows efficiently distinguishing between all three neutrino flavours, opening a unique opportunity to probe physics of heavy flavour production at the LHC in the region that is not accessible to ATLAS, CMS and LHCb. This region is of particular interest also for future circular colliders and for predictions of very high-energy atmospheric neutrinos. The physics programme includes studies of charm production, and lepton universality tests in the neutral sector. The detector concept is also well suited to searching for Feebly Interacting Particles via signatures of scattering in the detector target. The first phase aims at operating the detector throughout LHC Run 3 to collect a total of 250 fb−1. The experiment was installed in the TI18 tunnel at CERN and has collected its first data in 2022. A new era of collider neutrino physics has started.

Speaker: Maksym Ovchynnikov (Leiden University (NL))

13th_LLP_workshop_22_06_2023.pdf

41 The Run 3 milliQan detector: status, plans and first data

We will update on the status of the Run 3 milliQan detector that was installed over YETS 2022-23 and is currently being commissioned with LHC Run 3 pp collision data. A first look at these data will be presented.

Speaker: Michael Carrigan (Ohio State University (US))

MilliQan-LLP13.pdf

MilliQan-LLP13.pptx

42 Beyond-the-Standard Model searches with FASER

Speaker: John Anders (CERN)

FASER_LLP2023.pdf

43 First neutrino physics at colliders with FASER

FASER, the ForwArd Search ExpeRiment, is an LHC experiment located 480 m downstream of the ATLAS interaction point, along the beam collision axis. FASER and its sub-detector FASERnu have two physics goals: (1) to detect and study TeV-energy neutrinos, the most energetic neutrinos ever detected from a human-made source, and (2) to search for new light and very weakly-interacting particles. FASER was designed, constructed, installed, and commissioned during 2019-2022 and has been taking physics data since the start of LHC Run 3 in July 2022. This talk will present the status of the experiment, including detector design, detector performance, and first neutrino physics results from Run 3 data.

Speaker: Tomohiro Inada (Tsinghua University (CN))

2023FASER_LLP_Nu.pdf

15:10 Coffee

Experimental LLP project panoply: Session 4

Conveners: Lisa Benato (Hamburg University (DE)), Matthew Daniel Citron (University of California Davis (US))

44 FACET

Speakers: Aldo Penzo (infn), Aldo Penzo (University of Iowa (US))

LLP13-AP_22June2023.pdf

45 Installation of ANUBIS prototype tracker in the ATLAS cavern

The ANUBIS concept foresees instrumenting the ceiling and service shafts above the ATLAS experiment with tracking stations in order to search for LLPs with decay lengths of O(10m) and above. After a brief review of the physics case for the first complete prototype detector module proANUBIS, its installation in the ATLAS experimental cavern for data taking in 2023 will be presented.

Speaker: Dr Louie Corpe (Laboratoire de Physique de Clermont (LPC))

LCORPE_LLPWorkshop2023_ANUBIS_June2023.pdf

46 DAMSA

Speaker: Prof. Jae Yu (University of Texas at Arlington (US))

yu-damsa-at-pip2-llp2023-062223.pdf

yu-damsa-at-pip2-llp2023-062223.pptx

47 MATHUSLA

Speaker: Emma Torro Pastor (Univ. of Valencia and CSIC (ES))

Mathusla_13LHCLLP_June2023.pdf

Friday 23 June

Working group session: Comfortable, independent breakfast

New ideas in LLP phenomenology: Session 3

Conveners: Juliette Alimena (DESY), Louis Henry (EPFL - Ecole Polytechnique Federale Lausanne (CH))

48 Exploiting exotic LHC datasets for long-lived new particle searches

The LHC experiments collect not only the well-known proton-proton collision data but additionally also parking and scouting datasets as well as heavy-ion and low-pileup data. These datasets have a mild $p_T$ trigger threshold in common which might be beneficial for soft and long-lived new physics searches. I compare the discovery potential of such datasets using a GeV scale long-lived axion-like particles as an example.

Speaker: Jan Hajer (Universidade de Lisboa)

audio1917805340.m4a

Exploiting exotic LHC datasets for long-lived new particle searches

recording.conf

video1917805340.mp4

49 Testing neutrino dipole portal with long-lived particle detectors at the LHC

We discuss the potential of using detectors aimed for searching long-lived particles~(LLP) at the high-luminosity LHC run, to probe the neutrino dipole models. This is achieved by taking the heavy neutral leptons~(HNL) of the models as candidates of the LLPs. Taking into account the dipole couplings to the weak bosons, $d_{W,Z}$, which control the production of the HNLs at the LHC, we discuss the reach on the electromagnetic dipole couplings, $d_\gamma$, by searching for a single high-energy photon at LLP detectors. Four typical scenarios are considered in this paper, scenario A, B with $d_{W}=0$ or $d_{Z}=0$, and scenario C, D with $d_{W,Z}\gg d_\gamma$. We show the sensitivity on $d_\gamma$, can be fairly different depending on the relations between the $d_{W,Z}$ and $d_\gamma$. And the LLP detectors can potentially extend the sensitivity on dipole couplings during the High-luminosity runs of the LHC in certain scenarios.

Speaker: Wei Liu (Nanjing University of Science and Technology)

talk-Dipole-LLP.pdf

10:40 Coffee

New ideas in LLP phenomenology: Session 4

Conveners: Juliette Alimena (DESY), Louis Henry (EPFL - Ecole Polytechnique Federale Lausanne (CH))

50 Can we discover lepton number violation with LHC far detectors?

Two classes of far detectors have been proposed or are under operation at the LHC.
The first class is a series of neutrino detectors that are sensitive to light active neutrinos via either charged-current or neutral-current interactions; exemplary ideas are FASER$\nu$, SND@LHC, and FLArE. Another type aims primarily at looking for displaced decays of long-lived particles (LLPs) into charged final-state particles, including ANUBIS and FASER. In this work, we propose searches for probing lepton number violation associated with a Majorana active/sterile neutrino, for the first time with these experiments, which, if discovered, would be a clear signature of new physics beyond the Standard Model. With Monte-Carlo simulation, we find that while the neutrino detectors, unfortunately, are estimated to have signal-event rates orders of magnitude below $\mathcal{O}(1)$, some LLP far detectors such as ANUBIS, if upgraded, would be most promising for discovering a Majorana sterile neutrino of mass $\mathcal{O}(\text{1})$ GeV in certain so-far unexcluded parameter space. In this exploratory work, we emphasize on the importance of leveraging the LHC far detectors for purposes beyond the planned ones, such as searching for lepton number violation.

Speaker: Zeren Simon Wang (National Tsing Hua University)

audio1617269619.m4a

LNV_fardetectors.pdf

recording.conf

video1617269619.mp4

51 Environmentally aware displaced vertices

Dynamical theories of dark energy predict new degrees of freedom with particular environmental sensitivity to avoid constraints on fifth forces. We show that the similar, yet complementary multi-purpose detector setup of the ATLAS and CMS experiments provides a unique opportunity to place sensitivity on such scenarios in a narrow, yet relevant parameter range. Furthermore, our investigation gives rise to a novel phenomenological signature involving displaced vertices that the LHC experiments can pursue to exploit their complementary detector design from a BSM perspective. [arXiv:2304.08118]

Speakers: Clare Burrage (University of Nottingham), Spyros Argyropoulos (Albert Ludwigs Universitaet Freiburg (DE))

LLP2023.pdf

Experimental LLP project panoply: Session 5

Conveners: Andrii Usachov (Nikhef National institute for subatomic physics (NL)), Mason Proffitt (University of Washington (US))

52 CMS delayed jet trigger performance in Run 3

Speaker: Sai Neha Santpur (Univ. of California Santa Barbara (US))

CMSDelayedjets_LLP13_Neha-2.pdf

GMT20230623-095304_Recording_1920x1080.mp4

GMT20230623-095304_Recording.m4a

GMT20230623-095304_Recording.transcript.vtt

53 CMS: Run 3 Long Lived Particle Trigger with the CMS HCAL

Speaker: Gillian Baron Kopp (Princeton University (US))

LLP13_HCALtrigger_GKopp.pdf

54 Opportunity to search for the BSM physics at the ICARUS detector

The proposed Short-Baseline Neutrino (SBN) physics program at Fermilab will deliver rich and compelling physics opportunities, including the ability to resolve a class of experimental anomalies in neutrino physics. The main physics program of ICARUS detector, which functions as the far detector of the SBN program, is to deliver the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels and definitively resolve the LSND anomaly. Apart from sterile neutrino search, thanks to the superb performance of the detector and ideal location to detect the beam coming from on-axis BNB as well as off-axis NuMI beam, the ICARUS detector can provide an excellent opportunity to study other Beyond Standard Model (BSM) physics scenarios, such as dark matter (DM). In this, we will talk about the opportunity to search for BSM physics at the ICARUS detector at SBN.

Speaker: Animesh Chatterjee (University of Pittsburgh (US))

BSMSearch_ICARUS_LLP13_Chatterjee.pdf

55 Status of SUBMET at J-PARC

Electric charge quantization is a long-standing question in particle physics. While fractionally charged particles (millicharged particles hereafter) have typically been thought to preclude the possibility of Grand Unified Theories (GUTs), well-motivated dark-sector models have been proposed to predict the existence of millicharged particles while preserving the possibility for unification. Such models can contain a rich internal structure, providing candidate particles for dark matter. A number of experiments have searched for millicharged particles (𝜒s), but in the parameter space of the charge (𝑄) and mass ($𝑚_\chi$), the region of $𝑚_\chi>0.1$ $\rm{GeV}/c^2$ and $𝑄<10^{−3}𝑒$ is largely unexplored.

SUB-Millicharge ExperimenT (SUBMET) has been proposed to search for sub-millicharged particles using 30 GeV proton fixed-target collisions at J-PARC. The detector is composed of two layers of stacked scintillator bars and PMTs, and is proposed to be installed 280 m from the target. The main background is expected to be a random coincidence between the two layers due to dark counts in PMTs and the radiation from the surrounding materials, which can be reduced significantly using the timing of the proton beam. With $N_{POT}=5\times10^{21}$, the experiment provides sensitivity to 𝜒s with the charge down to $8×10^{−5}𝑒$ in $m_\chi<0.2$ $\rm{GeV}/c^2$ and $10^{−3}𝑒$ in $𝑚_\chi>1.6$ $\rm{GeV}/c^2$. This is the regime largely uncovered by the previous experiments.

Speaker: Jae Hyeok Yoo (Korea University (KR))

20230623_Jae_submet_llp13.pdf

56 Farewell