Description
Conveners:
Liron Barak (Tel Aviv University)
Lisa Benato (Universität Hamburg)
Dario Buttazzo (INFN Pisa)
Annapaola de Cosa (ETH)
Contact: eps23-conveners-t10 @desy.de
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,...
The Mu2e experiment, currently under construction at Fermilab, will search for neutrinoless mu->e conversion in the field of an aluminum atom. A clear signature of this charged lepton flavor violating two-body process is given by the monoenergetic conversion electron of 104.97 MeV produced in the final state.
An 8 GeV/c pulsed proton beam interacting on a tungsten target will produce the...
Some say SUSY is dead, because LHC has not discovered it yet. But is this
really true? It turns out that the story is more subtle. SUSY can be 'just
around the corner', even if no signs of it has been found and a closer
look is needed to quantify the impact of LHC limits and their implications
for future colliders. In this contribution, a study of prospects for SUSY
based on scanning...
A resonant structure has been observed at ATOMKI in the invariant mass of electron-positron pairs, produced after excitation of nuclei such as $^8$Be and $^4$He by means of proton beams. Such a resonant structure can be interpreted as the production of an hypothetical particle (X17) whose mass is around 17 MeV.
The MEG-II experiment at the Paul Scherrer Institut whose primary physics goal is...
Charged lepton flavor violation (CLFV) is an unambiguous signature of new physics. In the Belle experiment, we study various CLFV signatures, which include $\tau$ leptons in the final state. In this presentation, we report searches for CLFV in $\Upsilon(1S) \to \ell^{\pm}\ell^{\prime\mp}$ and $\chi_{bJ}(1P)\to \ell^{\pm}\ell^{\prime\mp}$ decays, where $\ell,\ell^\prime =e, \mu, \tau$ using ...
Supersymmetric models with low electroweak fine-tuning are more prevalent on the string landscape than fine-tuned models. We assume a fertile patch of landscape vacua containing the minimal supersymmetric standard model (MSSM) as a low-energy EFT. Such models are characterized by light higgsinos in the mass range of a few hundred GeV whilst top squarks are in the 1-2.5 TeV range. Other...
The existence of the magnetic monopole has eluded physicists for centuries. The NOvA Far Detector (FD), used for neutrino oscillation searches, also has the ability to identify magnetic monopoles. With a surface area of 4,100 m$^2$ and a location near the earth’s surface, the 14 kt FD provides us with the unique opportunity to be sensitive to potential low-mass monopoles unable to penetrate...
Electric dipole moments (EDMs) of elementary particles are powerful probes of CP-violating New Physics (NP). In the context of a general two-Higgs doublet model (2HDM) which due to lack of any ad hoc discrete symmetry possesses complex extra Yukawa couplings that can help explain baryon asymmetry of the Universe (BAU), we discuss their NP contribution to EDMs of lepton and quarks. In...
We study the impact of three different BSM models in the charge asymmetry defined for the 2SS$\ell$ (with $\ell= e, \mu$) with jets ($n_j\geq2$) final state at the LHC, at $\sqrt{s}=13$ TeV, where the main SM contribution is the $t\bar{t}W$ production. We consider the impact of a heavy neutral scalar/pseudoscalar arising from a 2HDM model; a simplified RPV MSSM model with electrowikino...
Several physics scenarios beyond the Standard Model predict the existence of new particles that can subsequently decay into a pair of Higgs bosons. These include pairs of SM-like Higgs bosons (HH) as well as asymmetric decays into two scalars of different masses (SH). This talk summarises ATLAS searches for resonant HH and SH production with LHC Run 2 data. Several final states are considered,...
An overview of the results of searches for massive new resonances by the CMS Collaboration is presented. The results include searches for resonances such as W' and Z' particles decaying to final states with top quarks as well as charged Higgs boson searches. The CMS search program covers a variety of final states targeting different new physics models including extended Higgs sectors. The...
In the Standard Model, one doublet of complex scalar fields is the minimal content of the Higgs sector in order to achieve spontaneous electroweak symmetry breaking. However, several theories beyond the Standard Model predict a non-minimal Higgs sector and introduce charged scalar fields that do not exist in the Standard Model. As a result, singly- and doubly-charged Higgs bosons would be a...
The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable of solely explaining some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs-like bosons. The current status of...
Following the potential discovery of new heavy particles at the LHC or a future collider, it will be crucial to determine their properties and the nature of the underlying Physics. Of particular interest is the possibility of Beyond-the-Standard-Model (BSM) scalar trilinear couplings.
In this talk, I will consider as a specific example the scalar top (stop) trilinear coupling parameter,...
Axion-like particles (ALPs) are gauge-singlet under the Standard Model (SM) and appear in many well-motivated extensions of the SM. Since they arise as pseudo-Nambu-Goldstone bosons of an approximate axion shift-symmetry, the masses of ALPs can naturally be much smaller than the energy scale of the underlying UV model, making them an attractive target for the Large Hadron Colloder (LHC) and...
Many theories beyond the Standard Model predict new phenomena giving rise to multijet final states. These jets could originate from the decay of a heavy resonance into SM quarks or gluons, or from more complicated decay chains involving additional resonances that decay e.g. into leptons. Also of interest are resonant and non-resonant hadronic final states with jets originating from a dark...
Many new physics models and Standard Model extensions like, additional symmetries and forces, compositeness, extra dimensions, extended Higgs sectors, supersymmetry, dark sectors and dark matter particles, are expected to manifest themselves in final states with hadronic jets. This talk will present recent searches for new phenomena in such final states using the full Run II luminosity...
The role of the Parton Distribution Functions (PDF) is crucial not only in the precise determination of the SM parameters, but also in the interpretation of new physics searches at the LHC. In this talk we show the potential of global PDF analyses to inadvertently ‘fit away’ signs of new physics, by identifying specific scenarios in which the PDFs may completely absorb signs of new physics,...
We study the influence of theoretical systematic uncertainties due to the quark density on LHC experimental searches for Z'-bosons.
Using an approach originally proposed in the context of the ABMP16 PDF set for the high-x behaviour of the quark density, we presents results on differential cross section and Forward-Backward asymmetry observables commonly used to study Z' signals in dilepton channels.
The Large Hadron-electron Collider and the Future Circular Collider in electron-hadron mode [1] will make possible the study of DIS in the TeV regime providing electron-proton collisions with per nucleon instantaneous luminosities of $10^{34}$ cm$^{−2}$s$^{−1}$. We review the possibilities for detection of physics beyond the SM in these experiments, focusing on feebly interacting particles...
Precision studies of the properties of the Higgs and gauge bosons may provide a unique window for the discovery of new physics at the LHC. New phenomena can in particular be revealed in the search for lepton-flavor-violating or exotic decays of the Higgs bosons, as well as in their possible couplings to hidden-sector states that do not interact under Standard Model gauge transformations. This...
Resonances in multi-boson final states (VVV, VV, VH, HH and HY, where V = W, Z and Y is a new scalar particle) with the CMS detector are presented. The results are based on the large dataset collected during Run 2 of the LHC at a centre-of-mass energy of 13 TeV. The analyses are optimised for high sensitivity over a large range in resonance mass. Many of the relevant backgrounds are estimated...
Leptoquarks are hypothetical particles that appear in many theoretical extensions of the Standard Model. They are predicted to mediate interactions between quarks and leptons, bridging the gap between the two fundamental classes of particles. Other theoretical models such as supersymmetry, introduce a link between bosons and fermions, predicting also additional particles such as stops. Both...
Many theories beyond the Standard Model predict new phenomena, such as heavy vectors or scalar, vector-like quarks, and leptoquarks in final states containing bottom or top quarks. Such final states offer great potential to reduce the Standard Model background, although with significant challenges in reconstructing and identifying the decay products and modelling the remaining background. The...
We present results for new heavy fermions at CMS. The results include searches for third-generation quark and lepton partners with vector-like properties. The results are based on the large dataset collected during Run 2 of the LHC at a centre-of-mass energy of 13 TeV. We search for these particles in a wide range of masses using several categories of reconstructed objects, from mulit-leptonic...
Many theories beyond the Standard Model predict new phenomena, such as Z', W' bosons, KK gravitons, or heavy leptons, in final states with isolated, high-pT leptons (e/mu/tau) or photons. Searches for new physics with such signatures, produced either resonantly or non-resonantly, are performed using the ATLAS experiment at the LHC. This includes a novel search that exploits the lepton-charge...
Many new physics models, such as the Sequential Standard Model, Grand Unified Theories, models of extra dimensions, or models with eg. leptoquarks or vector-like leptons, predict heavy mediators at the TeV energy scale. We present recent results of such searches in leptonic and photonic final states obtained using data recorded by the CMS experiment at Run-II of the LHC.
The physics program of the Higgs factory will focus on measurements of the 125 GeV Higgs boson, with the Higgs-strahlung process being the dominant production channel at 250 GeV. However, production of extra light scalars is still not excluded by the existing experimental data, provided their coupling to the gauge bosons is sufficiently suppressed. Fermion couplings of such a scalar could also...
The electron-positron stage of the Future Circular Collider (FCC-ee) is a precision frontier factory for Higgs, electroweak, flavour, top quark, and QCD physics. It is designed to operate in a 91-km circular tunnel built at CERN, and will serve as the first step towards O(100 TeV) proton-proton collisions. In addition to an essential Higgs program, the FCC-ee offers unique and powerful...
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This talk will review a number of these scenarios and present the expectations for searches at an electron-positron collider such as the International Linear Collider.
The cases discussed include SUSY...
Future e$^+$e$^-$ colliders, thanks to their clean environment and triggerless operation, offer a unique opportunity to search for long-lived particles (LLPs) at sub-TeV energies. Considered in this contribution are promissing prospects for LLP searches offered by the International Large Detector (ILD), with a Time Projection Chamber (TPC) as the core of its tracking systems, providing almost...
Muon colliders offer enormous potential for the exploration of the particle physics frontier, representing the unique possibility of combining the high centre-of-mass energy and luminosity of hadron colliders with very precise measurements of lepton machines. They provide an unprecedented physics reach from Standard Model (SM) processes to new physics beyond the SM. The contribution presented...
Exotic beyond the Standard Model signatures, such as long-lived particles or high-mass resonances, are prime examples of the physics potential of a high-energy muon collider. These experimental signatures impose significant constraints on the detector design and requirements on the event reconstruction techniques employed to analyse the data.
For example: dedicated track reconstruction...
The Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) features a sophisticated two-level triggering system composed of the Level 1 (L1), instrumented by custom-design hardware boards, and the High-Level Trigger (HLT), a software based trigger based on the complete event information and full detector resolution. The CMS L1 Trigger relies on separate calorimeter and muon...
We present the results from searches for SUSY signatures produced via the electroweak interaction. All searches use proton-proton collision data at a centre-of-mass energy of 13 TeV, recorded with the CMS detector during Run II of the LHC operations. The analyzed data correspond to an integrated luminosity of 137/fb. The results are interpreted within simplified models of electroweakino or...
Various theories beyond the Standard Model predict new, long-lived particles with unique signatures which are difficult to reconstruct and for which estimating the background rates is also a challenge. Signatures from displaced and/or delayed decays anywhere from the inner detector to the muon spectrometer, as well as those of new particles with fractional or multiple values of the charge of...
The direct production of electroweak SUSY particles, including sleptons, charginos, and neutralinos, is a particularly interesting area with connections to dark matter and the naturalness of the Higgs mass. The small production cross-sections and challenging experimental signatures lead to difficult searches. This talk will highlight the most recent results of searches performed by the ATLAS...
Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. Naturalness arguments favour supersymmetric partners of the gluons and third generation quarks with masses light enough to be produced at the LHC. This talk will present the latest results of searches conducted by the...
Many models beyond the standard model predict new particles with long lifetimes, such that the position of their decay is measurably displaced from their production vertex, and particles giving rise to other non-conventional signatures. We present recent results of searches for long-lived particles and other non-conventional signatures obtained using data recorded by the CMS experiment at...
There have been a lot of developments on identification of heavy objects decaying hadronically though large-size jets and tau leptons using machine learning techniques. These techniques have revolutionized searches for Supersymmetry at the LHC. In this talk, recent searches for Supersymmetry using heavy object tagging and tau leptons will be presented. The results are obtained from the...
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 that are shielded against SM backgrounds, and are therefore displaced from the proton-proton collision point. The CODEX-b detector, planned to be placed behind a thick...
The latest results of searches for supersymmetry in photonic final states with the CMS experiment will be presented. The analyses are based on the full dataset of proton-proton collisions collected during the Run 2 of the LHC at a center-of-mass energy of 13 TeV. The results are interpreted in models including the stealth SUSY models and gauge mediated supersymmetry breaking models.
SHADOWS (Search for Hidden And Dark Objects With the SPS) is a
proposed proton beam-dump experiment for the search of a large variety
of feeble-interacting particles (FIP) at the CERN SPS. It will exploit the
potential for searches and discoveries at the intensity frontier offered by
the upgrade of the ECN3 beam line.
SHADOWS, will be located off-axis, which allows the optimisation of...
Hidden sectors can help explain many important hints for new physics, but the large variety of viable models is a challenge for the model-independent interpretation of experimental light hidden particle searches. Standard techniques such as simplified models or effective field theories (EFTs) typically envision minimalist hidden sectors with only a single new particle, and it is not always...
Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. With increasing mass bounds on MSSM scenarios other non-minimal variations of supersymmetry become increasingly interesting. This talk will present the latest results of searches conducted by the ATLAS experiment...
Results from the CMS experiment are presented for supersymmetry searches targeting so-called compressed spectra, with small mass splittings between the different supersymmetric partners. Such a spectrum presents unique experimental challenges. This talk describes the new techniques utilized by CMS to address such difficult scenarios. The searches use proton-proton collision data at the center...
The idea that new physics could take the form of feebly interacting particles (FIPs) - particles with a mass below the electroweak scale, but which may have evaded detection due to their tiny couplings or very long lifetime - has gained a lot of attraction in the last decade, and numerous experiments have been proposed to search for such particles. It is important, and now very timely, to...
This talk presents a model independent search for an additional heavy, mostly sterile, neutral lepton (HNL) which is capable of mixing with the Standard Model tau neutrino with a mixing strength of $|U_{\tau 4}|^{2}$, corresponding to the square of the extended Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix element. HNLs are hypothetical particles predicted by many beyond-Standard-Model...
The smallness of neutrino masses, together with neutrino oscillations could be pointing to physics beyond the standard model, can be naturally accommodated by the so-called "seesaw" mechanism, in which new Heavy Neutral Majorana Leptons (HNL) are postulated. Several models with HNLs exist that incorporate the seesaw mechanism, sometimes also providing a DM candidate or giving a possible...
Neutrinos are the most elusive particles known. Heavier sterile neutrinos mixing with the Standard Model partners might solve the mystery of the baryon asymmetry of the universe and take part in the mass generation mechanism for the light neutrinos. Future lepton colliders, including e+e− Higgs factories, as well as multi-TeV electron and muon machines, will provide the farthest search reach...
MicroBooNE is an 85-tonne active mass liquid argon time projection chamber (LArTPC) at Fermilab. With an excellent calorimetric, spatial and energy resolution, the detector was exposed to two neutrino beams between 2015 and 2020. These characteristics make MicroBooNE a powerful detector not just to explore neutrino physics, but also for Beyond the Standard Model (BSM) physics. Recently,...
The Short-Baseline Near Detector (SBND) is a 112-ton liquid argon time projection chamber (LArTPC) detector located 110-meters downstream the Booster Neutrino Beam target at Fermilab. As the near detector of the Short-Baseline Neutrino Program, SBND is especially sensitive to any new particles produced in the beam. In addition to the excellent spatial and energy resolution of the LArTPC...
As the planning phases for a high-energy muon collider move into a new era, the issue of what new physics could be discovered becomes crucial. The discovery of neutrino oscillations has shown that neutrinos are massive and mixed, necessitating an extension of the Standard Model. In these extensions, neutrinos can acquire new interactions, namely neutrino non-standard interactions. On the other...
