scholarly journals PROBING GRAVITATIONAL INTERACTIONS OF ELEMENTARY PARTICLES

2004 ◽  
Vol 13 (10) ◽  
pp. 2355-2359 ◽  
Author(s):  
JONATHAN L. FENG ◽  
ARVIND RAJARAMAN ◽  
FUMIHIRO TAKAYAMA

The gravitational interactions of elementary particles are suppressed by the Planck scale M*~1018 GeV and are typically expected to be far too weak to be probed by experiments. We show that, contrary to conventional wisdom, such interactions may be studied by particle physics experiments in the next few years. As an example, we consider conventional supergravity with a stable gravitino as the lightest supersymmetric particle. The next-lightest supersymmetric particle (NLSP) decays to the gravitino through gravitational interactions after about a year. This lifetime can be measured by stopping NLSPs at colliders and observing their decays. Such studies will yield a measurement of Newton's gravitational constant on unprecedentedly small scales, shed light on dark matter, and provide a window on the early universe.

2017 ◽  
Vol 32 (15) ◽  
pp. 1740001 ◽  
Author(s):  
Maxim Yu. Khlopov

In the context of the relationship between physics of cosmological dark matter and symmetry of elementary particles, a wide list of dark matter candidates is possible. New symmetries provide stability of different new particles and their combination can lead to a multicomponent dark matter. The pattern of symmetry breaking involves phase transitions in the very early Universe, extending the list of candidates by topological defects and even primordial nonlinear structures.


1990 ◽  
Vol 05 (09) ◽  
pp. 645-651
Author(s):  
JORGE L. LOPEZ ◽  
D.V. NANOPOULOS

We recall the theoretical arguments that led us more than ten years ago to predict that there are only three generations. Quark-lepton mass relations (mb/mτ ≈ 2.8), as universally come out from unified theories at superhigh energies (close to the Planck scale), are the key point. We further argue that fractional deviations from Nν=3 may signal new physics. The supersymmetric decay Z→ÑÑ, with Ñ the lightest neutralino and lightest supersymmetric particle (LSP), easily fits the bill. In the specific case of flipped (SU(5)×U(1)) unification, there is a strong correlation between mt≈ O(90 ± 10) GeV, slepton masses of O(50 GeV) and the closure of the Universe due to Ñ dark matter, while ΔNν ≈ (0.1–0.5).


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jochem Hauser ◽  
Walter Dröscher

Abstract This article, the last in a series of three articles, attempts to unravel the underlying physics of recent experiments regarding the contradictory properties of the neutron lifetime that has been a complete riddle for quite some time. So far, none of the advanced theories beyond the  Standard Models (SMs) of particle physics and cosmology have shown sufficient potential to resolve this mystery. We also try to explain the blatant contradiction between the predictions of particle physics and experiments concerning the nature and properties of the (so far undetected) dark matter and dark energy particles. To this end the novel concepts of both negative and hypercomplex matter (giving rise to the concept of matter flavor) are introduced, replacing the field of real numbers by hypercomplex numbers. This extension of the number system in physics leads to both novel internal symmetries requiring new elementary particles – as outlined in Part I and II, and to novel types of matter. Hypercomplex numbers are employed in place of the widely accepted (but never observed) concept of extra space dimensions – and, hence, also to question the corresponding concept of supersymmetry. To corroborate this claim, we report on the latest experimental searches for novel and supersymmetric elementary particles by direct searches at the Large Hadron Collider (LHC) and other colliders as well as numerous other dedicated experiments that all have come up empty handed. The same holds true for the dark matter search at European Council for Nuclear Research (CERN) [CERN Courier Team, “Funky physics at KIT,” in CERN Courier, 2020, p. 11]. In addition, new experiments looking for dark or hidden photons (e.g., FUNK at Karlsruhe Institute of Technology, CAST at CERN, and ALPS at Desy, Hamburg) are discussed that all produced negative results for the existence of the hitherto unseen but nevertheless gravitationally noticeably dark matter. In view of this contradicting outcome, we suggest a four-dimensional Minkowski spacetime, assumed to be a quasi de Sitter space, dS 1,3, complemented by a dual spacetime, denoted by DdS 1,3, in which the dark matter particles that are supposed to be of negative mass reside. This space is endowed with an imaginary time coordinate, −it and an imaginary speed of light, ic. This means that time is considered a complex quantity, but energy m(ic)2 > 0. With this construction visible and dark matter both represent positive energies, and hence gravitation makes no distinction between these two types of matter. As dark matter is supposed to reside in dual space DdS 1,3, it is principally undetectable in our spacetime. That this is evident has been confirmed by numerous astrophysical observations. As the concept of matter flavor may possibly resolve the contradictory experimental results concerning the lifetime of the neutron [J. T. Wilson, “Space based measurement of the neutron lifetime using data from the neutron spectrometer on NASA’s messenger mission,” Phys. Rev. Res., vol. 2, p. 023216, 2020] this fact could be considered as a first experimental hint for the actual existence of hypercomplex matter. In canonical gravity the conversion of electromagnetic into gravity-like fields (as surmised by Faraday and Einstein) should be possible, but not in cosmological gravity (hence these attempts did not succeed), and thus these conversion fields are outside general relativity. In addition, the concept of hypercomplex mass in conjunction with magnetic monopoles emerging from spin ice materials is discussed that may provide the enabling technology for long sought propellantless space propulsion.


2012 ◽  
Vol 27 (12) ◽  
pp. 1230012 ◽  
Author(s):  
BOBBY SAMIR ACHARYA ◽  
GORDON KANE ◽  
PIYUSH KUMAR

In recent years it has been realized that in string/M theories compactified to four dimensions which satisfy cosmological constraints, it is possible to make some generic predictions for particle physics and dark matter: a nonthermal cosmological history before primordial nucleosynthesis, a scale of supersymmetry breaking which is "high" as in gravity mediation, scalar superpartners too heavy to be produced at the LHC (although gluino production is expected in many cases), and a significant fraction of dark matter in the form of axions. When the matter and gauge spectrum below the compactification scale is that of the MSSM, a robust prediction of about 125 GeV for the Higgs boson mass, predictions for various aspects of dark matter physics, as well as predictions for future precision measurements, can be made. As a prototypical example, M theory compactified on a manifold of G2 holonomy leads to a good candidate for our "string vacuum," with the TeV scale emerging from the Planck scale, a de Sitter vacuum, robust electroweak symmetry breaking, and solutions of the weak and strong CP problems. In this article we review how these and other results were derived, from the key theoretical ideas to the final phenomenological predictions.


Author(s):  
Arttu Rajantie

The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue ‘Higgs cosmology’.


Author(s):  
David DeMille

These lectures aim to explain how certain types of atomic, molecular, and optical physics experiments can have a substantial impact in modern particle physics. A central pedagogical goal is to describe, using only concepts familiar to atomic experimentalists, how new particles can lead to new terms in the atomic or molecular Hamiltonian. Well-motivated examples are discussed, including potential dark matter candidates known as “dark photons”, known and as-yet unknown Higgs bosons, and supersymmetric particles leading to CP violation. The observable effects of new Hamiltonian terms associated with these phenomena are worked out, and state-of-the-art strategies for detecting them, using atomic and molecular experiments, are described for some cases. Remarkably, the sensitivity of atomic/molecular experiments can make it possible to detect new particles even more massive than those that can be created directly at the largest high-energy colliders.


Author(s):  
P. J. E. Peebles

This chapter discusses the particle physicists' considerations of nonbaryonic matter. It takes into account the condition that if this nonbaryonic matter were produced in the hot early stages of expansion of the universe, then its remnant mass density must not exceed that allowed by the relativistic big bang cosmological model (again, assuming the relativistic theory). But it is notable that cosmologists took over the notion of nonbaryonic dark matter before the particle physics community had taken much interest in the astronomers' evidence of the presence of subluminal matter. The nonbaryonic dark matter most broadly discussed in the 1980s came in two varieties, cold and hot. The latter would be one of the known class of neutrinos with rest mass of a few tens of electron volts. The initially hot (meaning rapidly streaming) neutrinos in the early universe would have smoothed the mass distribution, and that smoothing would have tended to cause the first generation of structure to be massive systems that must have fragmented to form galaxies.


Author(s):  
Leonardo Badurina ◽  
Oliver Buchmueller ◽  
John Ellis ◽  
Marek Lewicki ◽  
Christopher McCabe ◽  
...  

We survey the prospective sensitivities of terrestrial and space-borne atom interferometers to gravitational waves generated by cosmological and astrophysical sources, and to ultralight dark matter. We discuss the backgrounds from gravitational gradient noise in terrestrial detectors, and also binary pulsar and asteroid backgrounds in space-borne detectors. We compare the sensitivities of LIGO and LISA with those of the 100 m and 1 km stages of the AION terrestrial AI project, as well as two options for the proposed AEDGE AI space mission with cold atom clouds either inside or outside the spacecraft, considering as possible sources the mergers of black holes and neutron stars, supernovae, phase transitions in the early Universe, cosmic strings and quantum fluctuations in the early Universe that could have generated primordial black holes. We also review the capabilities of AION and AEDGE for detecting coherent waves of ultralight scalar dark matter. AION-REPORT/2021-04 KCL-PH-TH/2021-61, CERN-TH-2021-116 This article is part of the theme issue ‘Quantum technologies in particle physics’.


2021 ◽  
Vol 16 (12) ◽  
pp. T12015
Author(s):  
C. He ◽  
J. Liu ◽  
X. Ren ◽  
X. Shang ◽  
X. Wei ◽  
...  

Abstract Waveform digitizers are key readout instruments in particle physics experiments. In this paper, we present a waveform digitizer for the PandaX dark matter experiments. It supports both external-trigger readout and triggerless readout, accommodating the needs of low rate full-waveform readout and channel-independent low threshold acquisition, respectively. This digitizer is a 8-channel VME board with a sampling rate of 500 MS/s and 14-bit resolution for each channel. A digitizer system consisting of 72 channels has been tested in situ of the PandaX-4T experiment. We report the system performance with real data.


2005 ◽  
Vol 14 (05) ◽  
pp. 751-762 ◽  
Author(s):  
J. D. VERGADOS ◽  
P. QUENTIN ◽  
D. STROTTMAN

The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat universe. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). Thus direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper, we study transitions to the excited states, focusing on the first excited state at 50 keV of Iodine A=127. We find that the transition rate to this excited state is ≼10 percent of the transition to the ground state. So, in principle, the extra signature of the gamma ray following its de-excitation can be exploited experimentally.


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