DOCSLIB.ORG

Hidden Worlds of Fundamental Particles David Curtin, and Raman Sundrum

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hidden Worlds of Fundamental Particles David Curtin, and Raman Sundrum Hidden worlds of fundamental particles David Curtin, and Raman Sundrum Citation: Physics Today 70, 6, 46 (2017); View online: https://doi.org/10.1063/PT.3.3594 View Table of Contents: http://physicstoday.scitation.org/toc/pto/70/6 Published by the American Institute of Physics Articles you may be interested in In the digital age, physics students and professors prefer paper textbooks Physics Today 70, 30 (2017); 10.1063/PT.3.3657 Commentary: Surviving scientist burnout Physics Today 70, 10 (2017); 10.1063/PT.3.3675 Microscopy without lenses Physics Today 70, 50 (2017); 10.1063/PT.3.3693 As student labor movements grow, scientists turn activist Physics Today 70, 32 (2017); 10.1063/PT.3.3623 Kamifusen, the self-inflating Japanese paper balloon Physics Today 70, 78 (2017); 10.1063/PT.3.3437 A bridge between undergraduate and doctoral degrees Physics Today 70, 50 (2017); 10.1063/PT.3.3464 David Curtin is a postdoctoral research associate and Raman Sundrum is a professor in the department of physics, both at the University of Maryland in College Park. HIDDEN WORLDS of fundamental particles David Curtin and Raman Sundrum Spectacular bursts of particles that seem to appear out of nowhere may shed light on some of nature’s most profound mysteries. hy is there something rather than nothing? It’s a incredible cancellation among unrelated W parameters. There exist more attractive question so basic and so vast in scope that it seems solutions, including supersymmetry and beyond the realm of quantitative inquiry. And yet surprisingly, it is the Higgs boson as a composite particle, that also predict high-energy signatures a question that can be framed and at least partially answered in the of new physics at the Large Hadron Col- study of particle physics. lider (LHC). Second, stuff exists only because at The standard model (SM) is our current theory of matter some point in the early universe, there was one extra particle and its interactions. Written in the language of relativistic quan- of SM matter for every one billion matter–antimatter pairs. That tum field theory, it has stood up to several decades of tests at tiny excess is all that remains today, and it must have been cre- high-energy colliders. We know, however, that it cannot be the ated dynamically in the primordial plasma of the Big Bang. In complete description of the universe, in large part because in the SM, that process—baryogenesis—is too weak by many or- several important regards it fails to answer the something- ders of magnitude; evidently, additional particles and interac- versus-nothing question. tions must have been present. Theorists have suggested many Material existence is connected to three fundamental mys- possibilities, including additional Higgs bosons and modified teries. First, why can matter clump to form a rich array of struc- Higgs couplings that could be detected at the LHC. tures without collapsing into black holes? The requisite weak- Third, strong interlocking evidence from a multitude of as- ness of gravity arises because the particles that make up everyday trophysical and cosmological observations suggests that dark matter are incredibly light. In the SM, the mass of all funda- matter makes up about 80% of the matter in the universe. We mental particles must be less than the electroweak mass, whose have no definitive knowledge of what it is or how it connects value of a few hundred GeV/c2 follows from the physics of the to the SM. The most popular theories predict a tiny interaction Higgs boson. However, when the effects of gravity are taken of dark matter with ordinary matter. Such a coupling would into account, the SM electroweak scale receives quantum con- enable direct detection by nuclear recoils in sensitive detectors tributions on the order of the Planck mass, 1018 GeV/c2. That and indirect detection in cosmic-ray data that show evidence puzzling discrepancy of scale is called the hierarchy problem. of dark-matter annihilation into SM particles. In the SM, a particle’s lightness is recovered only thanks to an The hierarchy problem, the riddle of matter–antimatter 46 PHYSICS TODAY | JUNE 2017 (GHOST) RIDERS IN THE SKY by Christopher Arabadjis, 2009. HIDDEN WORLDS Hidden-sector production Energy asymmetry, and the nature of dark matter drive much of ex- perimental and theoretical particle physics. Many experimen- Mediator tal searches for answers to those mysteries are proceeding vig- orously, but so far with null results across the board. That doesn’t a mean nothing is to be discovered. On the contrary, the null re- sults may well point us toward the true nature of the universe. There could be hidden sectors—additional particles and Higgs forces—with only tiny couplings to the SM. Far from being in- b consequential, those new sectors can address all three big mys- teries. Their signatures are subtle and easily missed, but luck- ily, their hidden nature is also the key to their discovery. Invisible long-lived particles (LLPs) can be produced at collid- c ers and decay into energetic SM particles after traveling an ap- Standard Hidden model sector preciable distance. Can we catch those revealing flashes? A tale of two frontiers Hidden-sector slow decay Physicists built the LHC in part to access new physics at mass scales higher than those characteristic of the SM. However, new FIGURE 1. PORTALS TO HIDDEN SECTORS. The diagram represents physics may be concealed, not by virtue of high mass, but by the energies of possible hidden-sector states in relation to those of very small couplings to the SM. We use the term “hidden sec- the standard model. Colored arrows indicate possible transitions tors” to refer to such disconnected non-SM matter and forces, between states. At the Large Hadron Collider, hidden-sector states which can arise robustly within the framework of quantum can be created by means of the production and decay of heavy field theories. mediators (a), exotic decays of the Higgs boson (b), or small direct (c) Like the push for higher energy, the investigation of hidden couplings . Once produced, the states decay through the same portals. Hidden-sector states have long lifetimes because the direct sectors with tiny couplings to visible particles has important couplings are small or because energy must be borrowed, courtesy historical precedent. Neutrinos are almost massless, and nowa- of the Heisenberg uncertainty principle, to excite the intermediate days they are understood to be related to charged leptons (elec- mediator or Higgs boson. trons, muons, and taus) through their shared weak interaction. Wolfgang Pauli postulated their existence in 1930 to restore conservation of momentum to beta decay, but their direct de- such a tiny keyhole, the decay can take a relatively long time. tection via scattering off nuclei wasn’t achieved until 1956, when That is what makes LLPs and their spectacular decays a hall- large neutrino fluxes from nuclear reactors became available. mark of hidden sectors. The discovery of the ghost-like neutrino sector was only the beginning, and those elusive particles still aren’t done confus- Solving mysteries ing us. For example, we know that neutrinos have masses and Searching for the flashes of LLP decays at the LHC and other oscillate from one type to another, which is not accounted for colliders will be a major enterprise. It will require dedicated in the SM. analyses and maybe new detectors, but it is well worth the ef- New hidden sectors can be connected to the SM by small fort. Here are just a few examples of how new sectors with hid- but nonzero couplings called portals. Figure 1 illustrates the den states address the three big mysteries. most important types. Portal couplings are small for several Let’s start with the hierarchy problem. As shown in figure 2, reasons. For example, symmetries can give rise to quantum me- known solutions cancel the top quark’s large quantum contri- chanical selection rules that force interactions between the SM bution to the Higgs (and thus electroweak) mass by introduc- and a hidden sector to proceed by means of a heavy and there- ing partners related to the top by a symmetry. In the case of fore hard-to-access mediator state. The mediator is not part of supersymmetry, the top partners take part in the SM’s strong the SM but interacts with both the SM and hidden sectors. interaction, so they should be produced in large numbers at It’s possible for some SM states—most importantly the pho- the LHC. ton and the Higgs boson—to function as a mediator. Although We haven’t found any sign of those partners yet, but another the structure of the theory makes the Higgs-portal and photon- solution, called neutral naturalness,3 relies on hidden valleys,4 portal couplings smaller than ordinary SM couplings, they are which are a family of theories that are essentially cousins of readily made much larger than the couplings of other types of quantum chromodynamics (QCD), the theory of the SM’s strong portals. Furthermore, accelerators produce lots of Higgs bosons interactions. Hidden valleys give rise to low-energy bound and photons. In rough analogy to an oscillating neutrino, a states; in analogy to SM protons and pions, they are called hid- photon could transform into a hidden photon and interact with den hadrons. In theories of neutral naturalness, the top partner hidden states.1 The Higgs boson, with a mass of 125 GeV/c2, is does not interact via the SM strong force, but it does interact heavy enough to sometimes decay directly into the hidden sec- via those hidden cousins of QCD.
Load more

Recommended publications
  • Axion Portal ⌘ [Weinberg, Wilczek, KSVZ, DFSZ] 4 EFT for a (Neutral) Dark Sector
    Snowmass RF6 - August 12, 2020 Dark Sector Portals at High Intensity Adam Ritz University of Victoria – New physics in a dark sector Empirical evidence for new physics, e.g. neutrino mass, dark matter, arguably points to a dark/hidden sector (but not directly to a specific mass scale) mediators Standard Model Dark Sector May contain light states, if UV Physics sufficiently weakly coupled • Neutrino mass - (HL)(HL)/ΛUV • DM - WIMPs etc Discoverability frontier IR Physics Direct • Neutrino mass - light (RH) singlets searches • DM - axions, sterile neutrinos, etc Energy Frontier Visibility Frontier ➠ Dark sectors present a huge model-space a priori, but an EFT approach to the mediator channel allows for a classification (large community effort over past decade) EFT for a (neutral) dark sector mediators Standard Model Dark Sector (+ gravity) There are just three UV-complete relevant or marginal “portals” to a SM-neutral hidden sector, unsuppressed by the (possibly large) new physics scale Λ c 1 = n (SM) (med) = + L ⇤n Ok Ol Lportals O ⇤ n=k+l 4 ✓ ◆ X− ✏ µ⌫ 2 ij 1 = B A0 H†H(AS + λS ) Y L¯ HN ++ −2 µ⌫ − − N i j OO ⇤ Vector portal Higgs portal Neutrino portal ✓ ◆◆ [Okun; Galison & Manohar; [Patt & Wilczek] Holdom; Foot et al] Many more UV-sensitive interactions at dim # 5 "3 EFT for a (neutral) dark sector mediators Standard Model Dark Sector (+ gravity) There are just three UV-complete relevant or marginal “portals” to a SM-neutral hidden sector, unsuppressed by the (possibly large) new physics scale ! c 1 = n (SM) (med) = + L ⇤n Ok Ol Lportals
    [Show full text]
  • Axions & Wisps
    FACULTY OF SCIENCE AXIONS & WISPS STEPHEN PARKER 2nd Joint CoEPP-CAASTRO Workshop September 28 – 30, 2014 Great Western, Victoria 2 Talk Outline • Frequency & Quantum Metrology Group at UWA • Basic background / theory for axions and hidden sector photons • Photon-based experimental searches + bounds • Focus on resonant cavity “Haloscope” experiments for CDM axions • Work at UWA: Past, Present, Future A Few Useful Review Articles: J.E. Kim & G. Carosi, Axions and the strong CP problem, Rev. Mod. Phys., 82(1), 557 – 601, 2010. M. Kuster et al. (Eds.), Axions: Theory, Cosmology, and Experimental Searches, Lect. Notes Phys. 741 (Springer), 2008. P. Arias et al., WISPy Cold Dark Matter, arXiv:1201.5902, 2012. [email protected] The University of Western Australia 3 Frequency & Quantum Metrology Research Group ~ 3 staff, 6 postdocs, 8 students Hosts node of ARC CoE EQuS Many areas of research from fundamental to applied: Cryogenic Sapphire Oscillator Tests of Lorentz Symmetry & fundamental constants Ytterbium Lattice Clock for ACES mission Material characterization Frequency sources, synthesis, measurement Low noise microwaves + millimetrewaves …and lab based searches for WISPs! Core WISP team: Stephen Parker, Ben McAllister, Eugene Ivanov, Mike Tobar [email protected] The University of Western Australia 4 Axions, ALPs and WISPs Weakly Interacting Slim Particles Axion Like Particles Slim = sub-eV Origins in particle physics (see: strong CP problem, extensions to Standard Model) but become pretty handy elsewhere WISPs Can be formulated as: Dark Matter (i.e. Axions, hidden photons) ALPs Dark Energy (i.e. Chameleons) Low energy scale dictates experimental approach Axions WISP searches are complementary to WIMP searches [email protected] The University of Western Australia 5 The Axion – Origins in Particle Physics CP violating term in QCD Lagrangian implies neutron electric dipole moment: But measurements place constraint: Why is the neutron electric dipole moment (and thus θ) so small? This is the Strong CP Problem.
    [Show full text]
  • Stabilized Singlets in Supergravity As a Source of the Μ-Parameter
    IASSNS-HEP-97-137 CERN-TH/98-75 RU-97-97 hep-ph/9803310 March 1998 Stabilized Singlets in Supergravity as a Source of the µ-parameter Christopher Kolda 1, Stefan Pokorski 2,3 and Nir Polonsky 4 1 School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540, USA 2 CERN Theory Division, CH-1211 Geneva 23, Switzerland 3 Institute of Theoretical Physics, Warsaw University, H˙oza 69, 00-681 Warsaw, Poland 4 Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA Abstract Within the context of supergravity-coupled supersymmetry, fields which are gauge and global singlets are usually considered anathema. Their vacuum ex- pectation values are shifted by quadratically divergent tadpole diagrams which are cutoff at the Planck scale, destabilizing the classical potential and driving the singlet field to large values. We demonstrate a new and generic mechanism which stabilizes the singlet in the presence of an extended gauge symmetry. Such a symmetry will be broken down to the Standard Model by the super- gravity interactions near the scale of spontaneous supersymmetry-breaking in the hidden-sector (∼ 1010−11 GeV). The resulting singlet expectation value is stabilized and naturally of order the gravitino mass, providing therefore a weak-scale mass for the Higgs fields of the supersymmetric Standard Model (a µ-parameter). The resulting low-energy theory is the minimal supersymmetric Standard Model, with all new fields decoupling at the intermediate scale. One of the primary motivations for low-energy supersymmetry (SUSY) is the stabilization of the weak scale (mW ) against quadratic divergences which appear at the quantum level and can drive mW up to the Planck scale (MP ).
    [Show full text]
  • The Future of Dark Matter and Dark Forces
    THE FUTURE OF DARK MATTER AND DARK FORCES International Symposium on the Future of Physics and Astronomy T. D. Lee Institute, Shanghai Jiao Tong University Jonathan Feng, University of California, Irvine 16 September 2017 16 Sep 2017 Feng 1 A HAPPY OCCASION Birthplace of my father in 1937 16 Sep 2017 Feng 2 DARK MATTER • “The Future of Physics and Astronomy”: Identifying dark matter is a central problem in both fields, and appreciation of its importance has grown rapidly in recent years 1997 2007 2017 LHC LHC LHC Gauge Hierarchy GaugeHierarchy GaugeHierarchy StandardModel Dark Matter Higgs Boson Higgs Boson Higgs Boson Dark Matter 16 Sep 2017 Feng 3 CLASSIC CANDIDATES • Three excellent candidates: sterile neutrinos, axions, WIMPs • Axions are highly motivated by the strong CP problem Peccei, Quinn (1977); Wilczek (1978); Weinberg (1978) • For axion DM, if θi ~1, then 12 fa ~ 10 GeV ma ~ 1-100 µeV Graham, Irastorza, Lamoreaux, Lindner, van Bibber (2016) 16 Sep 2017 Feng 4 LATEST RESULTS: ADMX G2 van Bibber (2017) 16 Sep 2017 Feng 5 WIMPs The WIMP Miracle WIMP Searches X q _ X q Feng (2008) • The WIMP miracle motivates diverse experiments that are (unfortunately) bigger, longer, and more expensive 16 Sep 2017 Feng 6 DIRECT DETECTION EXPERIMENTS (2013) Asymmetric nDM ~ nB 16 Sep 2017 Feng 7 LATEST RESULTS: PandaX-II 16 Sep 2017 Feng 8 RECENT DEVELOPMENTS • In the last few years, these classic candidates have been generalized to broad classes of dark matter Axions à Axion-like Particles (ALPs) à Ultralight DM WIMPs à WIMPless DMà Hidden Sector
    [Show full text]
  • The Beryllium Anomaly and New Physics
    THE BERYLLIUM ANOMALY AND NEW PHYSICS New Physics at the Intensity Frontier CERN-EPFL-Korea Theory Institute Jonathan Feng, University of California, Irvine 21 February 2017 21 Feb 2017 Feng 1 OUTLINE A. J. Krasznhorkay et al., “Observation of Anomalous Internal Pair Creation in 8Be: A Possible Indication of a Light, Neutral Boson,” 1504.01527 [nucl-ex], PRL 116, 042501 (2016) J. Feng et al., “Protophobic Fifth Force Interpretation of the Observed Anomaly in 8Be Nuclear Transitions,” 1604.07411 [hep-ph], PRL 117, 071803 (2016) J. Feng et al., “Particle Physics Models for the 17 MeV Anomaly in Beryllium Nuclear Decays,” 1608.03591 [hep-ph], PRD 95, 035017 (2017) Jonathan Bart Iftah Susan Jordan Tim Flip Feng Fornal Galon Gardner Smolinsky Tait Tanedo 21 Feb 2017 Feng 2 NEW PHYSICS AT THE INTENSITY FRONTIER • There are currently many outstanding puzzles: neutrino masses, gauge hierarchy, strong CP, flavor, dark matter, baryogenesis, dark energy,... • Some of these motivate searches for new particles and forces at high energies: the energy frontier • But some also motivate searches for new physics that is light, but weakly coupled: the intensity frontier • Of particular interest here are connections to dark matter 21 Feb 2017 Feng 3 DARK MATTER AT THE INTENSITY FRONTIER !!! 21 Feb 2017 Feng 4 DARK SECTORS • All evidence for dark matter is gravitational. Perhaps it’s in a hidden sector, composed of particles with no SM gauge interactions (electromagnetic, weak, strong) Visible Dark Sector Sector • The dark sector may have a rich structure with matter and forces of its own Lee, Yang (1956); Kobsarev, Okun, Pomeranchuk (1966); Blinnikov, Khlopov (1982); Foot, Lew, Volkas (1991); Hodges (1993); Berezhiani, Dolgov, Mohapatra (1995); Pospelov, Ritz, Voloshin (2007); Feng, Kumar (2008);..
    [Show full text]
  • Glueball Dark Matter in Non-Standard Cosmologies
    Prepared for submission to JHEP Glueball dark matter in non-standard cosmologies Bobby S. Acharya,a;b Malcolm Fairbairn,a Edward Hardyb;c aKings College London, Strand, London, WC2R 2LS, United Kingdom bAbdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy cDepartment of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL, United Kingdom E-mail: [email protected], [email protected], [email protected] Abstract: Hidden sector glueball dark matter is well motivated by string theory, compact- ifications of which often have extra gauge groups uncoupled to the visible sector. We study the dynamics of glueballs in theories with a period of late time primordial matter domina- tion followed by a low final reheating temperature due to a gravitationally coupled modulus. Compared to scenarios with a high reheating temperature, the required relic abundance is possible with higher hidden sector confinement scales, and less extreme differences in the entropy densities of the hidden and visible sectors. Both of these can occur in string derived models, and relatively light moduli are helpful for obtaining viable phenomenology. We also study the effects of hidden sector gluinos. In some parts of parameter space these can be the dominant dark matter component, while in others their abundance is much smaller than that of glueballs. Finally, we show that heavy glueballs produced from energy in the hidden sector prior to matter domination can have the correct relic abundance if they are sufficiently
    [Show full text]
  • Data-Driven Background Estimation Study for Stealth Supersymmetry
    UNIVERSIDAD SAN FRANCISCO DE QUITO USFQ Colegio de Ciencias e Ingenier´ıas Data-driven background estimation study for stealth supersymmetry searches in events with structure-rich jets and low missing energy in pp collisions at 8 TeV Particle Physics Proyecto de investigaci´on Santiago Rafael Paredes S´aenz F´ısica Trabajo de titulaci´onpresentado como requisito para la obtenci´ondel t´ıtulode Licenciatura en F´ısica Quito, 21 de diciembre de 2015 2 UNIVERSIDAD SAN FRANCISCO DE QUITO USFQ Colegio de Ciencias e Ingenier´ıas HOJA DE CALIFICACION´ DE TRABAJO DE TITULACION´ Data-driven background estimation study for stealth supersymmetry searches in events with structure-rich jets and low missing energy in pp collisions at 8 TeV Santiago Rafael Paredes S´aenz Calificaci´on: Nombre del profesor, T´ıtuloacad´emico: Edgar Carrera, Ph.D. Firma del profesor: Quito, 22 de diciembre de 2015 3 Derechos de Autor Por medio del presente documento certifico que he le´ıdo todas las Pol´ıticas y Manuales de la Universidad San Francisco de Quito USFQ, incluyendo la Pol´ıticade Propiedad Intelectual USFQ, y estoy de acuerdo con su contenido, por lo que los dere- chos de propiedad intelectual del presente trabajo quedan sujetos a lo dispuesto en esas Pol´ıticas. Asimismo, autorizo a la USFQ para que realice la digitalizaci´ony publicaci´onde este trabajo en el repositorio virtual, de conformidad a lo dispuesto en el Art. 144 de la Ley Org´anicade Educaci´onSuperior. Firma del estudiante: Nombres y apellidos: Santiago Rafael Paredes S´aenz C´odigo: 00103811 C´edulade Identidad: 1713475893 Lugar y fecha: Quito, diciembre de 2015 4 RESUMEN En vista de que las b´usquedasde supersimetr´ıaconcentradas en encontrar energ´ıa faltante no han sido exitosas hasta el momento, modelos alternativos c´omola super- simetr´ıasigilosa, que permiten poca, o ninguna, energ´ıafaltante han tomado mucho inter´es.
    [Show full text]
  • Dark Glueballs and Their Ultralight Axions
    Dark glueballs and their ultralight axions James Halverson, Brent D. Nelson, and Gustavo Salinas Department of Physics, Northeastern University, Boston, MA 02115-5000 USA Fabian Ruehle Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK Dark gauge sectors and axions are well-motivated in string theory. We demonstrate that if a confining gauge sector gives rise to dark glueballs that are a fraction of the dark matter, and the associated axion has a decay constant near the string scale, then this axion is ultralight and naturally realizes the fuzzy dark matter scenario with a modest tuning of a temperature ratio. Astrophysical observations constrain the size of the glueball component relative to the axionic component, while electric dipole moments constrain mixing with the QCD axion. Extended gauge and axion sectors are ubiquitous in the dark glueball problem is simultaneously eliminated. string theory and provide natural candidates for hidden Constraints on the model arising from astrophysics and sector dark matter. More specifically, gauge groups may electric dipole moment measurements are considered in have high rank, and gauge sectors that interact only via sections III A and III B, respectively. Finally, in sec- gravity, moduli, or axions are common. While not all tion IV, we discuss the scenario in a string theory con- string axions are necessarily associated with gauge sec- text, and consider how many of the assumptions made, tors, each gauge sector must couple via its field strength and conclusion drawn, are supported by broad arguments to some subset of the axions due to the dynamical nature in string theory.
    [Show full text]
  • Strongly Coupled Hidden Sector
    KANAZAWA-10-13 Electroweak and Conformal Symmetry Breaking by a Strongly Coupled Hidden Sector 1, 2, 1, 1, Martin Holthausen, ∗ Jisuke Kubo, y Kher Sham Lim, z and Manfred Lindner x 1Max-Planck-Institut f¨urKernphysik, 69117 Heidelberg, Germany 2Institute for Theoretical Physics, Kanazawa University, Kanazawa 920-1192, Japan Abstract The LHC and other experiments show so far no sign of new physics and long-held beliefs about naturalness should be critically reexamined. We discuss therefore in this paper a model with a combined breaking of conformal and electroweak symmetry by a strongly coupled hidden sector. Even though the conformal symmetry is anomalous, this may still provide an explanation of the smallness of electroweak scale compared to the Planck scale. Specifically we start from a classically conformal model, in which a strongly coupled hidden sector undergoes spontaneous chiral symmetry breaking. A coupling via a real scalar field transmits the breaking scale to the Standard Model Higgs and triggers electroweak symmetry breaking. The model contains dark matter candidates in the form of dark pions, whose stability is being guaranteed by the flavor symmetry of hidden quark sector. We study its relic abundance and direct detection prospects with the Nambu-Jona-Lasinio method and discuss the phase transition in the dark sector as well as in the electroweak sector. arXiv:1310.4423v2 [hep-ph] 15 Jan 2014 ∗ [email protected] y [email protected] z [email protected] x [email protected] 1 I. INTRODUCTION At the present level of our understanding, nature has (at least) three fundamental scales: the Planck scale MP l, where gravitational interactions become strong, the QCD scale ΛQCD at which the interactions of quantum chromodynamics (QCD) grow strong and the elec- troweak (EW) scale v = 246 GeV, around where - in the absence of the Higgs - the longitu- dinal gauge boson interactions would have become strong.
    [Show full text]
  • Statistical Coupling Constants from Hidden Sector Entanglement
    Statistical coupling constants from hidden sector entanglement Vijay Balasubramanian1;2∗, Jonathan J. Heckman1†, Elliot Lipeles1‡, and Andrew P. Turner1§ 1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 2Theoretische Natuurkunde, Vrije Universiteit Brussel and International Solvay Institutes, Pleinlaan 2, B-1050 Brussels, Belgium Abstract String theory predicts that the couplings of Nature descend from dynamical fields. All known string-motivated particle physics models also come with a wide range of possible extra sectors. It is common to posit that such moduli are frozen to a background value, and that extra sectors can be nearly completely decoupled. Performing a partial trace over all sectors other than the visible sector generically puts the visible sector in a mixed state, with coupling constants drawn from a quantum statistical ensemble. An observable consequence of this entanglement between visible and extra sectors is that the reported values of couplings will appear to have an irreducible variance. Including this variance in fits to experimental data arXiv:2012.09182v3 [hep-th] 9 Mar 2021 gives an important additional parameter that can be used to distinguish this scenario from the case where couplings are treated as fixed parameters. There is a consequent interplay between energy range and precision of an experiment that allows an extended reach for new physics. ∗e-mail: [email protected] †e-mail: [email protected] ‡e-mail: [email protected] §e-mail: [email protected] 1 Introduction The coupling constants of Nature are not truly \constant." This, at least, is what string theory predicts since such parameters descend from background values of moduli fields, the low energy remnants of higher-dimensional quantum gravity in our 4D world.
    [Show full text]
  • The Everpresent Eta-Problem: Knowledge of All Hidden Sectors
    Preprint typeset in JHEP style - HYPER VERSION ITFA10-44 The everpresent η-problem: knowledge of all hidden sectors required Sjoerd Hardemana, Johannes M. Oberreuterb, Gonzalo A. Palmac, Koenraad Schalma and Ted van der Aalsta aInstituut-Lorentz for Theoretical Physics, Universiteit Leiden Niels Bohrweg 2, Leiden, The Netherlands bInstituut voor Theoretische Fysica, Universiteit van Amsterdam Science Park 904, Amsterdam, The Netherlands cPhysics Department, FCFM, Universidad de Chile Blanco Encalada 2008, Santiago, Chile Email: [email protected], [email protected], [email protected], [email protected], [email protected] Abstract: We argue that the η-problem in supergravity inflation cannot be solved without knowledge of the ground state of hidden sectors that are gravitationally coupled to the inflaton. If the hidden sector breaks supersymmetry independently, its fields cannot be stabilized during cosmological evolution of the inflaton. We show that both the subsequent dynamical mixing between sectors as well as the lightest mass of the hidden sector are set by the scale of supersymmetry breaking in the hidden sector. The true cosmological η-parameter arises from a linear combination of the lightest mode of the hidden sector with the inflaton. Generically, either the true η deviates considerably from the na¨ıve η implied by the inflaton sector alone, or one has to consider a multifield model. Only if the lightest mass in the hidden sector is much larger than the inflaton mass and if the inflaton mass is much larger than the scale of hidden sector supersymmetry breaking, is the effect of the hidden sector on the slow-roll dynamics of the inflaton negligible.
    [Show full text]
  • Recent Progress in Search for Dark Sector Signatures M.A
    Recent Progress in Search for Dark Sector Signatures M.A. Deliyergiyev ∗ † ∗Department of Experimental Particle Physics, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia, and †Department of High Energy Nuclear Physics, Institute of Modern Physics, CAS, Nanchang Road 509, 730000 Lanzhou, China Submitted to Open Physics Many difficulties are encountered when attempting to pinpoint a clusters, the rotation curves of galaxies, large scale structure common origin for several observed astrophysical anomalies, and simulations and observations from high-z supernovae, collid- when assessing their tension with existing exclusion limits. These ing clusters of galaxies, gravitational lensing and so on [4, 6]. include systematic uncertainties affecting the operation of the de- Over the last 15 years we have established with very high tectors, our knowledge of their response, astrophysical uncertainties, confidence that the matter density (visible and dark) accounts and the broad range of particle couplings that can mediate interac- 1 tion with a detector target. Particularly interesting astrophysical for only 27% of the critical value ΩM + ΩΛ ≈ 1 , so the rest is evidence has motivated a search for dark-photon, and focused our attributed to the vacuum energy density, and thus to the cos- attention on a Hidden Valleys model with a GeV-scale dark sector mological constant. Moreover, we have concluded from CMB that produces exciting signatures. Results from recent underground data that the Universe has a dark, or vacuum, energy density experiments are also considered. ΩΛ, of 0.73, which seems to be eerily uniform – smoothly dis- There is a `light' hidden sector (dark sector), present in many mod- tributed through space, and persistent (non-diluting) through els of new physics beyond the Standard Model, which contains a time.
    [Show full text]