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# Forward Physics Facility - Kickoff Meeting

Europe/Zurich
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Participants
• Agustin Sabio Vera
• Ahmed Ismail
• Akitaka Ariga
• Albert De Roeck
• Ameen Ismail
• Andrea Coccaro
• Anna Sfyrla
• Baha Balantekin
• Ben Nachman
• Brian Batell
• Brian Petersen
• Brooks Thomas
• Carlo Enrico Pandini
• Carlo Giunti
• Carlos Perez de los Heros
• Charles Timmermans
• Chiara Rizzi
• Chris Hill
• Christopher Hearty
• Claire Antel
• Claire Lee
• Cristian Baldenegro Barrera
• Cynolter Gábor
• Danny Marfatia
• Deion Elgin Fellers
• Dennis Soldin
• Digesh Raut
• Dipan Sengupta
• EK NARAYAN PAUDEL
• Fatemeh Taghavi-shahri
• Fei Huang
• Felix Kling
• Florian Urs Bernlochner
• Fnu Karan Kumar
• Francesco Giuli
• Francis Halzen
• Francisco Martínez López
• Frank Golf
• Frank Krauss
• Gianluigi Arduini
• Giovanni De Lellis
• Giuseppe Iacobucci
• Grigorios Chachamis
• Guanghui Zhou
• Gustavo Gil Da Silveira
• Hallsie Reno
• Hans Peter Dembinski
• Hassane Hamdaoui
• Herbi Dreiner
• Hidetoshi Otono
• Holger Schulz
• Hsin-Chia Cheng
• Hye-Sung Lee
• Iftah Galon
• Ina Sarcevic
• Jakob Salfeld-Nebgen
• James Beacham
• Jamie Boyd
• Janusz Chwastowski
• Jason Kumar
• Jeffrey Gao
• John Osborne
• John Stupak
• Jonathan Feng
• Jonathan Gall
• Jongkuk Kim
• Josu Hernandez
• juan carlos Helo
• Keith Dienes
• Kento Asai
• Kevin Kelly
• Kristof Schmieden
• Krzysztof Jodłowski
• LINGFENG LI
• Ljiljana Morvaj
• Luca Lavezzo
• Luis Anchordoqui
• Marco Dallavalle
• Maria Vittoria Garzelli
• Mario Campanelli
• Mariusz Przybycien
• Martin Hirsch
• Matt LeBlanc
• Matthew Daniel Citron
• Mauro Valli
• Meshkat Rajaee
• Michaela Queitsch-Maitland
• Milind Diwan
• Osamu Sato
• Patrick deNiverville
• Patrick Foldenauer
• Percy Cáceres
• Piotr Kotko
• Pouya Bakhti
• Pyungwon Ko
• Rafal Maselek
• Ralph Engel
• Roman Pasechnik
• Roshan Mammen Abraham
• Rouven Essig
• Ruben Conceição
• Saeid Foroughi Abari
• Sascha Mehlhase
• Savannah Rose Shively
• Sebastian Trojanowski
• Serap TILAV
• Sergey Ostapchenko
• Sho Iwamoto
• Shufang Su
• Spencer Chang
• Steven Lowette
• Sumit Ghosh
• Takashi Shimomura
• Tanguy Pierog
• Tania Robens
• Tao Han
• Tao Xu
• Tevong You
• Thomas Gaisser
• Thomas Rizzo
• Tianlu Yuan
• Tomoko Ariga
• Torbjörn Sjöstrand
• Tyler Smith
• Valery Khoze
• vernon barger
• Victor Goncalves
• Vishvas Pandey
• Weidong Bai
• Wlodek Guryn
• Yasaman Farzan
• Yongchao Zhang
• Yongsoo Jho
• Yosuke Takubo
• Yu Seon Jeong
• Yu-Dai Tsai
• Zoltan Trocsanyi
• Zoltán Péli
Jonathan Lee Feng, Maria Vittoria Garzelli, Felix Kling
• Monday, November 9
• Introduction and Overview
Convener: Jonathan Lee Feng (University of California Irvine (US))
• 1
FPF Overview
Speaker: Jonathan Lee Feng (University of California Irvine (US))
• 2
FPF Civil Engineering: Initial Study
Speaker: Jonathan Gall (CERN)
• 3
Infrastructure Requirements and Particle Fluxes and Environment
Speaker: Jamie Boyd (CERN)
• Discussion / Coffee Break
• BSM Physics Opportunities and Experiments
Convener: Felix Kling (SLAC)
• 4
BSM Physics Overview
Speaker: Ahmed Ismail
• 5
FASER2 and potential connection with the FPF
Speaker: Brian Petersen (CERN)
• 6
Talk: FASERnu 2 and potential connection with the FPF
Speaker: Dr Akitaka Ariga (Universitaet Bern (CH))
• 7
Talk: SND@LHC and potential connection with the FPF
Speaker: Giovanni De Lellis (Universita e sezione INFN di Napoli (IT))
• 8
Talk: MilliQan and potential connection with the FPF
Speaker: Chris Hill (Ohio State University (US))
• Discussion / Coffee Break
• Dark Sectors and Cosmology
Convener: Jonathan Lee Feng (University of California Irvine (US))
• 9
FORMOSA & Forward-DUNE - Looking Forward to Millicharged Dark Sectors and New Neutrino Physics

We identify potentially the world's most sensitive location to search for millicharged particles in the 10 MeV to 100 GeV mass range: the forward region at the LHC. We propose constructing a scintillator-based experiment, FORward MicrOcharge SeArch (FORMOSA) in this location, and estimate the corresponding sensitivity projection. We show that FORMOSA can discover millicharged particles in a large and unexplored parameter space, and study strongly interacting dark matter that cannot be detected by ground-based direct-detection experiments. The newly proposed LHC Forward Physics Facility (FPF) provides an ideal structure to host the full FORMOSA experiment.
This talk is based on arXiv:2010.07941 & arXiv:1812.03998.
I will also discuss the new idea of studying neutrino physics at FPF with the newly proposed Forward-DUNE experiment.

Speaker: Dr Yu-Dai Tsai (Fermilab)
• 10
Potential for BSM and Neutrino Physics at FORMOSA

In this talk, I will present some additional physics potential of FORMOSA, that not only provides leading sensitivity to MCPs but also is extremely sensitive to other forms of exotica beyond the standard model (BSM), such as heavy neutrinos and DM with a large electric dipole moment (EDM). Furthermore, we expect a sizable number of interactions of TeV-energy neutrinos in FORMOSA, providing additional opportunities for neutrino physic in the far forward direction.

Speaker: Mr Saeid Foroughi (University of Victoria)
• 11
Light Dark Matter at the Forward Physics Facility

Light sub-GeV dark matter particles interacting through a kinetically mixed dark photon may be copiously produced in the far-forward region at the LHC. These dark matter particles may then be detected through their scattering off electrons. We show that thousands of scattering events may be detected in the HL-LHC era by a 10-ton emulsion detector placed on the beam collision axis 500 m from the ATLAS interaction point in the proposed Forward Physics Facility. We consider the leading backgrounds from neutrino-electron scattering, neutrino quasi-elastic scattering, charged current deep inelastic scattering, and muon-induced photon pair production. With an upstream magnet to mitigate low-energy muons and optimized cuts on the electron energy and direction, we find that such an emulsion detector can probe the entire thermal relic region for masses mA' between 10 and 100 MeV.

Speaker: Brian Thomas Batell
• 12
Looking for light new particles with secondary production in the far-forward region of the LHC

One of the primary aims of the Forward Physics Facility (FPF) would be to search for highly-displaced decays of light and long-lived particles (LLPs) produced in proton-proton collisions at the LHC. These searches are, however, limited to new particles with decay lengths similar to or larger than the baseline of the FPF. We will discuss how this basic constraint can be overcome in models that go beyond the simplest BSM scenarios thanks to a possible secondary production of LLPs right in front of the detector. A similar mechanism would allow one to treat the FPF as a high-energy neutrino beam-dump experiment to probe BSM couplings of the SM neutrinos.

Speaker: Krzysztof Jodlowski (National Centre for Nuclear Research)
• 13
Collider signatures of minimal freeze in models

We propose simple freeze-in models where the observed dark matter abundance is explained via the decay of an electrically charged and/or coloured parent particle into Feebly Interacting Massive Particles (FIMP). The parent particle is long-lived and yields a wide variety of LHC signatures depending on its lifetime and quantum numbers. We assess the current constraints and future high luminosity reach of these scenarios at the LHC from searches for heavy stable charged particles, disappearing tracks, displaced vertices and displaced leptons. We show that the LHC constitutes a powerful probe of freeze-in dark matter and can further provide interesting insights on the validity of vanilla baryogenesis and leptogenesis scenarios. We also discuss how future experiments like FASER and Mathusla can probe these models.

Speaker: Dipan Sengupta (UC San Diego)
• 14
Freeze-in Dark Matter in U(1) extended Standard Model and Lifetime Frontier Experiments

In the context of a well-motivated gauged U(1) extension of the Standard Model, we introduce a non-thermal dark matter whose interaction is too weak to allow it to be in thermal equilibrium with the Standard Model particles, and its relic density is determined by the freeze-in mechanism through a light mediator that is the extra U(1) gauge boson. We discuss a complementarity between the cosmological constraint on this dark matter physics and the planned/proposed Lifetime Frontier experiments to search for a long-lived particle.

Speaker: Nobuchika Okada (University of Alabama)
• 15
Hunting Inflaton at FASER

We consider the nonminimal quartic inflation in a classically conformal U(1)$_X$ extended SM. We show that if the inflaton mass and its mixing angle with the SM Higgs field lie in a suitable range, the FASER experiment can search for the inflaton at the High Luminosity (HL)-LHC. Also because of the classical conformal invariance, the inflationary predictions and the LHC search for the U(1)$_X$ gauge boson ($Z^\prime$) resonance are complementary. Therefore, three independent experiments, namely, the inflaton search at the FASER, the $Z^\prime$ boson resonance search at the HL-LHC and the precision measurement of the inflationary predictions, are complementary to test our inflation scenario.

Speaker: Dr Digesh Raut (University of Delaware)
• Long-Lived Particles
Convener: Felix Kling (SLAC)
• 16
Long Lived Light Supersymmetric Neutralinos

We have investigated the search sensitivity to long lived light neutralinos, with masses below a few GeV down to 10s of MeV, at various forward detectors. The can be produced at the LHC via rare decays of standard mesons or via rare Z-boson decays. The neutralinos decay to a lighter meson plus a charged lepton, which can be observed. We have studied a large set of proposed experiments: ANUBIS; AL3X; CODEX-b; Faser1,2; MATHUSLA, MOEDAL-MAPP1,2; SHiP; but also ATLAS.

Speaker: Herbi Dreiner (Bonn University)
• 17
Pinning down the Flavour Structure of Hidden Photons

Extensions of the Standard Model with an abelian gauge group are constrained by gauge anomaly cancellation, fermion masses and mixing angles. These constraints only allow for a limited number of $U(1)_X$ groups. We categorise these extensions and determine the allowed textures of Yukawa and Majorana mass matrices. If neutrinos are Dirac, the only possible choice satisfying all conditions is the $U(1)_{B-L}$ group, whereas all other $U(1)_X$ extensions require Majorana masses. This generically results in flavour changing couplings of the $X$ gauge boson to neutrinos. In the future, FASER$\nu$ 2 could play a crucial role in constraining these groups from searching for deviations of the flavour composition of the incoming neutrino flux from the SM prediction.

Speaker: Patrick Foldenauer
• 18
Opportunities for probing $U(1)_{T3R}$ with light mediators

We consider strategies for using new datasets to probe
scenarios in which light right-handed SM fermions couple
to a new gauge group, $U(1)_{T3R}$. This scenario
provides a natural explanation for the light flavor
sector scale, and a motivation for sub-GeV dark matter.
There is parameter space which is currently allowed, but
we find that much of it can be probed with future
experiments. In particular, experiments which search for displaced visible
decay or invisible decay, cosmological and
astrophysical observations, neutrino experiments can all play a role. Still,
there is a small region of parameter space which even
these upcoming experiments will not be able to probe.

Speaker: Sumit Ghosh (Texas A & M University)
• 19
Dark Photon from Light Scalar Boson Decays at FASER

FASER is one of the promising experiments which search for long-lived particles in beyond standard models.
In this paper, we focus on dark photon associating with an additional U(1) gauge symmetry, and also a scalar boson
breaking this U(1) gauge symmetry.
We study the sensitivity to the dark photon originated from U(1)-breaking scalar decays.
We find that sizable number of the dark photon signatures can be expected
in wider parameter space
than previous studies.

Speakers: Takashi Shimomura (University of Miyazaki), Takashi Shimomura (University of Valencia), Takashi Shimomura
• 20
Probe Light Scalars in 2HDMs at FASER

Two Higgs Doublet Model (2HDM) offers a prototype for models with an extended Higgs sector beyond that of the Standard Model. It provides a rich spectrum of scalars, some of them can be relatively light with relatively weak couplings. Complementary to the usual searches for extra scalars at high energy colliders, FASER offers a unique opportunity to study those relatively long lived light scalars. Given all the existing theoretical and experimental constraints, we consider the light CP-even and CP-odd scalars in the four different types of 2HDMs, and examine the parameter window which can be probed at FASER.

Speaker: Shuailong Li
• 21
Long-lived Sterile Neutrinos at the LHC in Effective Field Theory

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 via higher-dimensional operators arising from potentially new, decoupled physics. We study scenarios where sterile neutrinos are predominantly produced via rare charm and bottom mesons decays at LHC experiments. If sterile neutrinos are long-lived, their decay can lead to displaced vertices which can be reconstructed. We investigate the search sensitivities for the ATLAS/CMS detector, the future far-detector experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA, and MoEDAL-MAPP, and at the proposed fixed-target experiment SHiP. We focus on HNL production and decay from dimension-six operators involving quarks in the $\nu$SMEFT Lagrangian and perform simulations to determine the potential reach of high-luminosity LHC experiments in probing these EFT operators.

Speaker: Guanghui Zhou (University of Massachusetts Amherst)
• 22
Search for sterile neutrino with light gauge interactions: recasting collider, beam-dump, and neutrino telescope searches

We investigate features of the sterile neutrinos in the presence of a light gauge boson $X$ that couples to the neutrino sector. The novel bounds on the active-sterile neutrino mixings $| U_{\ell 4} |^2$, especially for muon and tau flavors ($l = \mu, \tau$), from various collider and fixed target experiments in intensity frontiers are explored. Also, taking into account the additional decay channel of the sterile neutrino into a light gauge boson ($\nu_4 \to \nu_\ell e^+ e^-$), we explore and constrain a parameter space for low energy excess in neutrino oscillation experiments.

Speaker: Yongsoo Jho
• 23
LLP and neutrino mass models

In this talk I will discuss the connection of different neutrino mass models with long-lived particles (LLPs). We will also discuss the prospects of the LHC and several recent experimental proposals to search for these LLPs.

Speaker: Dr juan carlos Helo (Universidad de La Serena)
• QCD and Neutrinos
Convener: Maria Vittoria Garzelli
• 24
Neutral Current Neutrino Interactions at FASERnu

Charged current neutrino interactions have been extensively studied in the context of various experiments, including FASER$\nu$. The presence of a charged lepton in the final state allows for easy identification of candidate signal events and incoming beam energy reconstruction. Neutral current neutrino interaction on the other hand have a neutrino in the final state. This imposes two challenges: a) differentiating signal from background, which is primarily neutral hadron induced in FASER$\nu$ and b) reconstructing incoming beam energy when the final state has missing energy. In this work we propose to use machine learning tools to identify and reconstruct signal events. We show how a suitable choice of event observables and proper training of the neural network can allow us to constrain NC neutrino cross-section in the 100GeV - a few TeV range. We convert this cross-section sensitivity to limits on neutrino NSI.

Speaker: Roshan Mammen Abraham (Oklahoma State University)
• 25
DsTau (NA65) Experiment at CERN-SPS

Tau neutrino is the least known particle of the Standard Model, first discovered by DONUT experiment in 2001. In DONUT, using tau neutrino interaction cross section was measured with large systematical (~50%) and statistical (~30%) errors. The main source of systematical error is due to a poor knowledge of the tau neutrino flux from Ds decays. The DsTau experiment at CERN-SPS has been proposed to measure an inclusive differential cross-section of a 𝐷𝑠 production with a consecutive decay to tau lepton in p-A interactions. The goal of experiment is to reduce the systematic uncertainty from 50% to 10%. The accurate measurement of the cross-section is not only important for future neutrino experiments but also for testing the Lepton Flavour Universality (LFU) of Standard Model. In addition to the tau neutrino production study, DsTau can also study charmed particle production in proton interactions. About 10^5 charm events are expected to be detected in DsTau. The detector is based on nuclear emulsion providing a sub-micron resolution for the detection of short length and small “kink” decays. Therefore, it is very suitable to search for peculiar decay topologies (“double kink”) of Ds→τ →X.

After successful pilot runs and data analysis, CERN had approved the DsTau project as a new experiment NA65 in 2019. About an order of magnitude more data than the pilot runs will be collected in physics runs scheduled in 2021-2022. In this talk, the results of the pilot run data analysis will be presented and the prospect for physics runs in 2021-2022 will be given.

Speaker: Osamu Sato (Nagoya University (JP))
• 26
Prompt neutrinos in the forward region at the LHC

We calculate the prompt muon and tau neutrino (and antineutrino) number of events in the far forward region at the LHC. In a region as such, the heavy quark decay dominates the tau neutrino production. The hadronic charm and bottom hadron production cross section is evaluated at the next-to-leading order in perturbative QCD. The intrinsic transverse momentum of the initial partons becomes important in this region and is modeled with a Gaussian function, with the parameter determined by fitting to the LHCb experimental data. The heavy quark fragmentation is described by the Peterson fragmentation function. Thousands of charged current tau (anti)neutrino events can be expected for a 1 m long lead neutrino detector located 480 m down the stream for pp collision at a center-of-mass energy $\sqrt{s}$ = 14 TeV and an integrated luminosity L = 3000 fb$^{−1}$. However, the uncertainties from the perturbative QCD higher-order corrections are large in the neutrino event distribution.

Speaker: Dr Weidong Bai (University of Iowa)
• 27
Tau neutrino oscillations in the far forward rapidities

In the very forward region of the LHC, a number of tau neutrinos can be produced mostly from the $D_s^\pm$ decay. For an integrated luminosity of 3000 $\rm fb^{-1}$ at the HL-LHC, thousands of charged current tau neutrino events are expected in a detector of $\rm m^3$ size. It will allow the study of the mixing between sterile neutrinos and tau neutrinos with the fact that the possible specifics of the experiments at the Forward Physics Facility would be insensitive to oscillation between the standard model neutrinos. We will present a case-study of tau neutrino oscillations considering a 3+1 neutrino model with three active neutrinos and a sterile neutrino with a testable parameter set and discuss the potential and challenges for its investigation.

Speaker: Yu Seon Jeong (University of Iowa (US))
• 28
Discovery potential of FASERnu with contained vertex and through-going events

The FASER$\nu$ detector is a newly proposed detector whose main mission is to detect neutrino flux from the collision of the proton beams at the ATLAS Interaction Point (IP) during run III of the LHC in 2021-2023. We show that this detector can also test certain beyond standard model scenarios, especially the ones in which the neutrino interaction with matter fields can produce new unstable particles decaying back into charged leptons. Such scenarios are also motivated by the MiniBooNE anomaly. The detector will be located 480 m away from the interaction point such that neutrinos have to cross 10 meters of concrete and 90 meters of soil before reaching the detector. We show that if the new physics involves multi-muon production by neutrinos scattering off matter fields, including the neutrino flux interactions in the rock before the detector in the analysis ({\it i.e.,} accounting for the through-going muon pairs) can significantly increase the effective mass of the detector to search for new physics. We develop a model that can give rise to such multi-muon signal.

Speaker: Prof. Yasaman Farzan (IPM)
• 29
High-energy muons at the Forward Physics Facility

Muons produced at the LHC are the only Standard Model species besides neutrinos that can reach in large numbers the Forward Physics Facility. A combination of their typical high energy and very precise experimental tools to study their flux and interactions will open up a possibility for new exciting searches in this unique low-background environment. In the talk, we will mention a few such opportunities that could initiate further discussions about a possible far-forward muon-physics program at the LHC.

Speaker: Sebastian Trojanowski
• 30
Mueller-Navelet jets phenomenology

We give a short review of recent Mueller-Navelet jets studies at the LHC and we propose new related observables to be used as probes of the BFKL dynamics.

Speaker: Grigorios Chachamis (LIP, Lisbon)
• 31
QCD measurements at the LHC to solve the Muon Puzzle in cosmic ray showers
Speaker: Dr Hans Peter Dembinski (TU Dortmund)
• Tuesday, November 10
• Implications for Parton Distribution Functions
Convener: Grigorios Chachamis (LIP, Lisbon)
• 32
QCD for inclusive forward charm production at the LHC
Speaker: Pavel Nadolsky (Southern Methodist University)
• 33
(n)PDF issues and opportunities at the Forward Physics Facility
Speaker: Maria Vittoria Garzelli
• 34
Further thoughts..... & Discussion
Speaker: Dr Grigorios Chachamis (LIP, Lisbon)
• Implications for general-purpose MC event generators and non-perturbative uncertainties
Convener: Holger Schulz (University of Durham)
• 35
Forward Physics in PYTHIA 8
Speaker: Torbjorn Sjostrand (Lund University (SE))
• 36
General Purpose MC Forward Physics
Speaker: Frank Martin Krauss (University of Durham (GB))
• 37
Further thoughts..... & Discussion
Speaker: Dr Holger Schulz (University of Durham)
• Inplications for Cosmic Ray Physics and generators
Convener: Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE))
• 38
Forward production in MC generators: constraints from other observables and relevance for high energy cosmic ray studies
Speaker: Sergey Ostapchenko (Frankfurt Institute for Advanced Studies (FIAS))
• 39
Forward hadronization: the key of muon production in air showers
Speaker: Dr Tanguy Pierog (KIT)
• 40
Further thoughts..... & Discussion
Speaker: Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE))
• Implications for the modelization of the Physics of Cosmic and Atmospheric Neutrinos
Convener: Mary Hall Reno
• 41
IceCube and Forward Charm Production
Speaker: Francis Halzen (University of Wisconsin)
• 42
Muon and Neutrino Fluxes in IceCube
Speaker: Dennis Soldin (University of Wuppertal)
• 43
Further thoughts..... & Discussion
Speaker: Mary Hall Reno
• Summary and Conclusions
Convener: The organizers
• 44
Summary and conclusions
Speaker: Felix Kling (SLAC)