Search For Exotic Particles Research Articles

Extragalactic electromagnetic cascades and cascade gamma-ray emission in magnetic fields of various strength

We discuss the magnetic field influence on diffuse gamma-ray emission from extragalactic electromagnetic cascades initiated by ultra-high energy cosmic rays. Regions in space vary considerably in field strength: it is possibly of 10−12 G and lower in voids, of ∼10−6 G inside galaxies, galactic clusters and groups, of ∼10−7 G around them, and of ∼10−8–10−9 G in filaments. Structures having fields higher than in voids occupy comparatively small fraction of the Universe, so they affect weakly on cascade emission. Still knowledge of this influence may be relevant studying large-scale component of the extragalactic magnetic field and to the search for exotic particles, as in the latter case contribution of all components to extragalactic gamma-ray background should be known, one of which is cascade emission. To study magnetic field effect we simulate particle propagation in homogeneous magnetic field of ∼10−6, 10−9, and 10−12 G and lower. It is found that in fields of ∼10−9 G and lower the spectra of diffuse cascade gamma-rays at energies E ≤ 1017 eV coincide. Thus no specific models of EGMF are required to study contribution of cascade emission in the extragalactic gamma-ray background at E ≤ 1017 eV. In the case of uniform field of 10−6 G (which seems to be unrealistic), this inference is valid in the energy range of ∼107109 eV. Results obtained can be also used studying large-scale component of the extragalactic magnetic field.

Performance of the NA62 trigger system

The NA62 experiment at CERN targets the measurement of the ultra-rare {K}^{+}to {pi}^{+}nu overline{nu} decay, and carries out a broad physics programme that includes probes for symmetry violations and searches for exotic particles. Data were collected in 2016–2018 using a multi-level trigger system, which is described highlighting performance studies based on 2018 data.

HIKE: High Intensity Kaon Experiments at the CERN SPS

The availability of high intensity kaon beams at the CERN SPS North Area gives rise to unique possibilities for sensitive tests of the Standard Model in the quark flavor sector. Precise measurements of the branching ratios for the flavor-changing neutral current decays can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. Building on the success of the NA62 experiment, plans are taking shape at CERN for a comprehensive program that will include experimental phases to measure the branching ratio for to ∼5% and to to ∼20% precision. These planned experiments would also carry out lepton flavor universality tests, lepton number and flavor conservation tests, and perform other precision measurements in the kaon sector, as well as searches for exotic particles in kaon decays. We overview the physics goals, detector requirements, and project status for the next generation of kaon physics experiments at CERN.

Foreword

The International Conference on Kaon Physics 2022 – KAON2022 – was held on September 13-16, 2022 at the Nambu Yoichiro Hall in the Toyonaka Campus of Osaka University, Japan.At the previous KAON2019 which was held in September 2019 at Perugia, it was decided that the next conference will be held in Osaka in September 2022. At that time, nobody knew what the entire world had to go through between the two KAON Conferences. Many other conferences were canceled or postponed, and many have switched to a pure online style. In November 2021, as we saw some hope for having a face-to-face meeting, the International Advisory Committee (IAC) for KAON2022 decided to hold the Conference as scheduled in hybrid style. Still, due to unpredictable variants of the virus and border restrictions, the expected number of attendants had a large uncertainty. The conference had to be prepared for a wide range of possibilities.At the end, however, the Conference had 53 participants attending in person, of which 29 were from 13 countries abroad. We also had 53 people registered for online participation. There were 47 oral presentations of which 25 were given in person, and 19 poster presentations.Oral presentations covered experimental and theoretical aspects of kaon rare decays, semileptonic decays, radiative decays, the CKM matrix, violations in CP, T, CPT, and lepton number, hadron physics, quantum mechanics, exotic particle searches, and future perspectives. We also had review talks on flavor physics in neighboring fields, including theoretical overview, and experiments on B mesons, neutrinos, and muons.The poster session was also held in hybrid style. All the posters were posted physically in the Nambu Hall, and their PDF files were also posted in a virtual poster session room on a platform called Gather. For each poster in the Hall, a rented iPad was hung next to it. Each iPad was connected to Gather, and showed the same poster. Effectively, the iPad served as a window between the real and virtual worlds. Through the window, the presenter and audience could see each other and have discussions just as if they were standing in front of the poster.List of Conference Home Page, Participants, Posters are available in this Pdf.

Scattering of charged particles off monopole\u2013anti-monopole pairs

The Large Hadron Collider is reaching energies never achieved before allowing the search for exotic particles in the TeV mass range. In a continuing effort to find monopoles we discuss the effect of the magnetic dipole field created by a pair of monopole–anti-monopole or monopolium on the successive bunches of charged particles in the beam at LHC.

Search for the X(5568) Exotic State in the CMS Experiment

The search for exotic particles decaying into $$B_s^0\pi^{\pm}$$ , performed in the CMS experiment by the authors of this paper, is described.

Search for Exotic Particles at the NA62 Experiment

The NA62 experiment at the CERN Super Proton Synchrotron (SPS) is currently taking data to measure the ultra-rare decay K + → π + ν ν ¯ . The high-intensity setup, trigger flexibility, detector performance and high-efficiency vetoes make NA62 also suitable for direct searches of long-lived, beyond-the-Standard-Model particles, such as Heavy Neutral Leptons (HNLs), Axion-Like Particles (ALPs) and Dark Photons (DPs); moreover, many rare and forbidden decays are studied at NA62. The status of all these searches is reviewed, together with prospects for future data taking at NA62 after the CERN Long Shutdown 2 (LS2).

A measurement of material in the ATLAS tracker using secondary hadronic interactions in 7 TeV pp collisions

Knowledge of the material in the ATLAS inner tracking detector is crucial in understanding the reconstruction of charged-particle tracks, the performance of algorithms that identify jets containing b-hadrons and is also essential to reduce background in searches for exotic particles that can decay within the inner detector volume. Interactions of primary hadrons produced in pp collisions with the material in the inner detector are used to map the location and amount of this material. The hadronic interactions of primary particles may result in secondary vertices, which in this analysis are reconstructed by an inclusive vertex-finding algorithm. Data were collected using minimum-bias triggers by the ATLAS detector operating at the LHC during 2010 at centre-of-mass energy √s = 7 TeV, and correspond to an integrated luminosity of 19 nb−1. Kinematic properties of these secondary vertices are used to study the validity of the modelling of hadronic interactions in simulation. Secondary-vertex yields are compared between data and simulation over a volume of about 0.7 m3 around the interaction point, and agreement is found within overall uncertainties.

Constraints on Exotic Dipole-Dipole Couplings between Electrons at the Micrometer Scale.

New constraints on exotic dipole-dipole interactions between electrons at the micrometer scale are established, based on a recent measurement of the magnetic interaction between two trapped 88Sr(+) ions. For light bosons (mass≤0.1 eV) we obtain a 90% confidence interval for an axial-vector-mediated interaction strength of |g(A)(e)g(A)(e)/4πℏc|≤1.2×10(-17). Assuming CPT invariance, this constraint is compared to that on anomalous electron-positron interactions, derived from positronium hyperfine spectroscopy. We find that the electron-electron constraint is 6 orders of magnitude more stringent than the electron-positron counterpart. Bounds on pseudoscalar-mediated interaction as well as on torsion gravity are also derived and compared with previous work performed at different length scales. Our constraints benefit from the high controllability of the experimental system which contained only two trapped particles. It therefore suggests a useful new platform for exotic particle searches, complementing other experimental efforts.

Searching for exotic particles in high-energy physics with deep learning.

Collisions at high-energy particle colliders are a traditionally fruitful source of exotic particle discoveries. Finding these rare particles requires solving difficult signal-versus-background classification problems, hence machine-learning approaches are often used. Standard approaches have relied on 'shallow' machine-learning models that have a limited capacity to learn complex nonlinear functions of the inputs, and rely on a painstaking search through manually constructed nonlinear features. Progress on this problem has slowed, as a variety of techniques have shown equivalent performance. Recent advances in the field of deep learning make it possible to learn more complex functions and better discriminate between signal and background classes. Here, using benchmark data sets, we show that deep-learning methods need no manually constructed inputs and yet improve the classification metric by as much as 8% over the best current approaches. This demonstrates that deep-learning approaches can improve the power of collider searches for exotic particles.

Recent results from operation of the ANTARES deep-sea neutrino telescope

The ANTARES neutrino telescope is currently the largest operating water Cherenkov detector and the largest neutrino detector in the Northern hemisphere. It comprises 885 optical modules distributed on 12 detection lines anchored at a depth of 2.5km in the Mediterranean Sea near Toulon, France; at a latitude that accesses a large part of the Galactic Plane, including the Galactic Centre. Its main scientific target is the detection of multi-TeV neutrinos predicted in charged cosmic particle acceleration mechanisms. In addition, ANTARES has developed a range of multi-messenger search strategies to look for correlations with optical counterparts and other cosmic messengers including γ-rays and charged cosmic rays. Other topics of investigation include the search for neutrinos from dark matter annihilation, searches for exotic particles and the measurement of neutrino oscillations. Details of the telescope are discussed together with examples of recently-conducted searches.

Recent results from the ANTARES neutrino telescope

The ANTARES neutrino telescope is currently the largest operating water Cherenkov detector and the largest neutrino detector in the Northern Hemisphere. Its main scientific target is the detection of high-energy (TeV and beyond) neutrinos from cosmic accelerators, as predicted by hadronic interaction models, and the measurement of the diffuse neutrino flux. Its location allows for surveying a large part of the Galactic Plane, including the Galactic Centre.In addition to the standalone searches for point-like and diffuse high-energy neutrino signals, ANTARES has developed a range of multi-messenger strategies to exploit the close connection between neutrinos and other cosmic messengers such as gamma-rays, charged cosmic rays and gravitational waves. This contribution provides an overview of the recently conducted analyses, including a search for neutrinos from the Fermi bubbles region, searches for optical counterparts with the TAToO program, and searches for neutrinos in correlation with gamma-ray bursts, blazars, and microquasars. Further topics of investigation, covering e.g. the search for neutrinos from dark matter annihilation, searches for exotic particles and the measurement of neutrino oscillations, are also reviewed.

Study of ΛΛ correlations and search for H-dibaryon with STAR detector at RHIC

The production of large number of multi-strange hyperons per central nucleus–nucleus collision at RHIC allows us to study hyperon–hyperon interactions through measurement of two particle correlation and search for exotic particles like H-dibaryons. In this article, we discuss analysis details for the measurement of ΛΛ correlation in Au+Au collisions at sNN=200GeV. Fits to different potential models are discussed and the extracted scattering length and effective range are also presented. Finally, we report the progress in searching for the H-dibaryon, a six quark state Jaffe (1977) [1], using its weak decay Λpπ from Au+Au collisions at sNN=200GeV.

High energy neutrino telescopes in the Northern Hemisphere

We review the status and results of the high energy neutrino telescopes in the Northern Hemisphere, namely ANTARES and Baikal (NT200+). After a brief introduction to Neutrino Astronomy, we describe these telescopes in their past and present configurations and report briefly on the results obtained in several areas, such as the search for high energy cosmic neutrino diffuse fluxes and point sources, the indirect search for dark matter, the multimessenger studies and the search for exotic particles, such as monopoles and nuclearites.

Search for new forms of matter in antimatter–matter interactions in the panda experiment

The Panda experiment is a key experiment at FAIR – European Facility for Antiproton and Ion Research, which is in the development stage in Darmstadt (Germany). The physical program of the experiment is focused on the search for exotic particles, research on hadron spectroscopy, the structure of nucleons, nuclear-matter effects, hypernuclei, and in other areas. New experimental forms of matter predicted by theory – glueballs and hybrids – are of great interest. They have not yet been observed. The PANDA facility will be assembled in the storage ring of the HESR antiproton beam. Antiprotons with energy from 1.5 to 15 GeV will be accumulated in the ring. Up to 2·107 interactions/sec are expected on the internal hydrogen (cluster or corpuscular) target. In addition to the high luminosity of the experiment (2·1032 cm–2·sec–1), the beam will be monochromatic. Because of stochastic and electronic cooling, pulsed stretching of the beam is expected to be at the level 10–4–10–5, which makes it possible to measure the mass of the particles with record high resolution 100 keV. Domestic institutes are participating in the development of the PANDA facility.

Looking for magnetic monopoles at LHC with diphoton events

Magnetic monopoles have been a subject of interest since Dirac established the relation between the existence of monopoles and charge quantization. The intense experimental search carried thus far has not met with success. The Large Hadron Collider is reaching energies never achieved before allowing the search for exotic particles in the TeV mass range. In a continuing effort to discover these rare particles we propose here other ways to detect them. We study the observability of monopoles and monopolium, a monopole-antimonopole bound state, at the Large Hadron Collider in the $\gamma \gamma$ channel for monopole masses in the range 500-1000 GeV. We conclude that LHC is an ideal machine to discover monopoles with masses below 1 TeV at present running energies and with 5 fb$^{-1}$ of integrated luminosity.

KM3NeT: Present status and potentiality for the search for exotic particles

The aim of the KM3NeT Project is to build a very large volume (more than 1 km 3) neutrino telescope in the Mediterranean Sea. The up to date status of the project is presented, and the main physics goals are reviewed. The possibility to search for super-massive exotic particles (magnetic monopoles, nuclearites, Q-balls) is addressed in the final part of the paper.

Exotic Particle Searches with STAR at RHIC

We present preliminary results of the STAR experiment at RHIC on exotic particle searches in minimum bias Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. We observe a narrow peak at 1734 $\pm$ 0.5 $\pm$ 5 MeV in the $\Lambda K^0_s$ invariant mass with width consistent with the experimental resolution of about 6 MeV within the errors. The statistical significance can be quantified between 3 and 6 $\sigma$ depending on cuts and methods. If this peak corresponds to a real particle state it would be a candidate for the $N^0$ or the $\Xi^0$ I=1/2 pentaquark states.

Vanishing pentaquarks

After a first inconclusive sighting, the search for exotic particles that consist of five quarks has been hotly pursued in the past few years. But the weight of evidence is now shifting against their existence.

Calibrations of CR39 and Makrofol nuclear track detectors and search for exotic particles

We present the final results of the search for exotic massive particles in the cosmic radiation performed with the MACRO underground experiment. Magnetic monopoles and nuclearites flux upper limits obtained with the CR39 nuclear track subdetector, the scintillation and streamer tube subdetectors are given. Searches at high altitude with the SLIM experiment are in progress.