Gluino

In supersymmetry, a gluino (symbol

) is the hypothetical supersymmetric partner of a gluon.

In supersymmetric theories, gluinos are Majorana fermions and interact via the strong force as a color octet.[1] Gluinos have a lepton number 0, baryon number 0, and spin 1/2.

Experimentally, gluinos have been the one of the most promising SUSY particle candidates to be discovered since the production cross-section is the highest among SUSYs in the energy-frontier hadron colliders such as Tevatron and the Large Hadron Collider (LHC).[2] The experimental signatures are typically a pair-produced gluinos and their cascade decays. In models of supersymmetry that conserve R-parity, gluinos eventually decay into the undetected lightest super-symmetric particle with many quarks (looking as jets) and the standard model gauge bosons or Higgs bosons. In the R-parity violating scenarios, gluinos can either decay promptly into multiple jets, or be long-lived leaving anomalous sign of "displaced decay vertices" from the interaction point where they are generated.

Though there has been no sign of gluinos observed so far, the strongest limit has been set by LHC (ATLAS/CMS) where up to minimum 1 TeV and maximum 2 TeV in gluino mass has been excluded.[3][4]

Footnotes

  1. ^ As there are eight gluons of different color combinations, there are eight gluinos of different color combinations, too.
  2. ^ Lincoln, Don (2013-07-03). "Supersymmetric glue: the search for gluinos". CERN. cms.web.cern.ch. Retrieved 28 April 2016.
  3. ^ "SupersymmetryPublicResults < AtlasPublic < TWiki". twiki.cern.ch. Retrieved 21 April 2019.
  4. ^ "PhysicsResultsSUS < CMSPublic < TWiki". twiki.cern.ch. Retrieved 21 April 2019.
Exotic baryon

Exotic baryons are a type of hadron (bound states of quarks and gluons) with half-integer spin, but have a quark content different to the three quarks (qqq) present in conventional baryons. An example would be pentaquarks, consisting of four quarks and one antiquark (qqqqq̅).

So far, the only observed exotic baryons are the pentaquarks P+c(4380) and P+c(4450), discovered in 2015 by the LHCb collaboration.Several types of exotic baryons that require physics beyond the Standard Model have been conjectured in order to explain specific experimental anomalies. There is no independent experimental evidence for any of these particles. One example is supersymmetric R-baryons, which are bound states of 3 quarks and a gluino. The lightest R-baryon is denoted as S0 and consists of an up quark, a down quark, a strange quark and a gluino. This particle is expected to be long lived or stable and has been invoked to explain ultra-high-energy cosmic rays. Stable exotic baryons are also candidates for strongly interacting dark matter.

It has been speculated by futurologist Ray Kurzweil that by the end of the 21st century it might be possible by using femtotechnology to create new chemical elements composed of exotic baryons that would eventually constitute a new periodic table of elements in which the elements would have completely different properties than the regular chemical elements.

Gauge boson

In particle physics, a gauge boson is a force carrier, a bosonic particle that carries any of the fundamental interactions of nature, commonly called forces. Elementary particles, whose interactions are described by a gauge theory, interact with each other by the exchange of gauge bosons—usually as virtual particles.

All known gauge bosons have a spin of 1. Therefore, all known gauge bosons are vector bosons.

Gauge bosons are different from the other kinds of bosons: first, fundamental scalar bosons (the Higgs boson); second, mesons, which are composite bosons, made of quarks; third, larger composite, non-force-carrying bosons, such as certain atoms.

Gaugino

In supersymmetry theories of particle physics, a gaugino is the hypothetical fermionic supersymmetric field quantum (superpartner) of a gauge field, as predicted by gauge theory combined with supersymmetry. All gauginos have spin 1/2, except for gravitino (spin 3/2).

In the minimal supersymmetric extension of the standard model the following gauginos exist:

The gluino (symbol g͂) is the superpartner of the gluon, and hence carries color charge.

The gravitino (symbol G͂) is the supersymmetric partner of the graviton.

Three winos (symbol W͂± and W͂3) are the superpartners of the W bosons of the SU(2)L gauge fields.

The bino is the superpartner of the U(1) gauge field corresponding to weak hypercharge.Sometimes the term "electroweakinos" is used to refer to winos and binos and on occasion also higgsinos.

Glossary of string theory

This page is a glossary of terms in string theory, including related areas such as supergravity, supersymmetry, and high energy physics.

G̃ (disambiguation)

G̃ or g̃ is the letter G with a tilde.

G̃ or g̃ may also mean:

g̃, a gluino

G̃, a gravitino

Higher-dimensional supergravity

Higher-dimensional supergravity is the supersymmetric generalization of general relativity in higher dimensions. Supergravity can be formulated in any number of dimensions up to eleven. This article focuses upon supergravity (SUGRA) in greater than four dimensions.

Index of physics articles (G)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

Lightest Supersymmetric Particle

In particle physics, the lightest supersymmetric particle (LSP) is the generic name given to the lightest of the additional hypothetical particles found in supersymmetric models. In models with R-parity conservation, the LSP is stable; in other words, the LSP cannot decay into any Standard Model particle, since all SM particles have the opposite R-parity. There is extensive observational evidence for an additional component of the matter density in the Universe that goes under the name dark matter. The LSP of supersymmetric models is a dark matter candidate and is a weakly interacting massive particle (WIMP).

List of particles

This article includes a list of the different types of atomic and sub-atomic particles found or hypothesized to exist in the whole of the universe, categorized by type. Properties of the various particles listed are also given, as well as the laws that the particles follow. For individual lists of the different particles, see the list below.

Michael Dine

Michael Dine (born 12 August 1953, Cincinnati, Ohio) is an American theoretical physicist, specializing in elementary particle physics, supersymmetry, string theory, and physics beyond the Standard Model.

Mikhail Shifman

Mikhail "Misha" Arkadyevich Shifman (Russian: Михаи́л Арка́дьевич Ши́фман; born 4 April 1949) is a theoretical physicist (high energy physics), formerly at Institute for Theoretical and Experimental Physics, Moscow, currently Ida Cohen Fine Professor of Theoretical Physics, William I. Fine Theoretical Physics Institute, University of Minnesota.

Minimal Supersymmetric Standard Model

The Minimal Supersymmetric Standard Model (MSSM) is an extension to the Standard Model that realizes supersymmetry. MSSM is the minimal supersymmetrical model as it considers only "the [minimum] number of new particle states and new interactions consistent with phenomenology". Supersymmetry pairs bosons with fermions, so every Standard Model particle has a superpartner yet undiscovered. If we find these superparticles, it equates to discovering such particles as dark matter, could provide evidence for grand unification, and provide hints as to whether string theory describes nature. The failure to find evidence for supersymmetry using the Large Hadron Collider suggests a leaning to abandon it.

Naturalness (physics)

In physics, naturalness is the property that the dimensionless ratios between free parameters or physical constants appearing in a physical theory should take values "of order 1" and that free parameters are not fine-tuned. That is, a natural theory would have parameter ratios with values like 2.34 rather than 234000 or 0.000234.

The requirement that satisfactory theories should be "natural" in this sense is a current of thought initiated around the 1960s in particle physics. It is an aesthetic criterion, not a physical one, that arises from the seeming non-naturalness of the standard model and the broader topics of the hierarchy problem, fine-tuning, and the anthropic principle. However it does tend to suggest a possible area of weakness or future development for current theories such as the Standard Model, where some parameters vary by many orders of magnitude, and which require extensive "fine-tuning" of their current values of the models concerned. The concern is that it is not yet clear whether these seemingly exact values we currently recognize, have arisen by chance (based upon the anthropic principle or similar) or whether they arise from a more advanced theory not yet developed, in which these turn out to be expected and well-explained, because of other factors not yet part of particle physics models.

The concept of naturalness is not always compatible with Occam's razor, since many instances of "natural" theories have more parameters than "fine-tuned" theories such as the Standard Model. Naturalness in physics is closely related to the issue of fine-tuning, and over the past decade many scientists argued that the principle of naturalness is a specific application of Bayesian statistics.

R-hadron

R-hadrons are hypothetical particles composed of a Supersymmetric particle and at least one quark.

Ryan Rohm

Ryan Milton Rohm (born 22 December 1957, Gastonia, North Carolina) is an American string theorist. He is one of four physicists known as the Princeton string quartet, and is responsible for the development of heterotic string theory along with David Gross, Jeffrey A. Harvey and Emil Martinec, the other members of the Princeton String Quartet.

Rohm studied physics and mathematics at North Carolina State University (NCSU) with bachelor's degree in 1980 and received a Ph.D. in physics from Princeton University in 1985. He was a postdoc from 1985 to 1988 at Caltech. From 1988 to 1995 he was an assistant professor at Boston University. In 1997 he earned a master's degree in computer science at NCSU. Since 1998 he has worked on experimental neutrino physics in the KamLAND experiment and at the Triangle Universities Nuclear Laboratory (TUNL). Since 1997 he has also been an adjunct professor at the University of North Carolina at Chapel Hill.

Split supersymmetry

In particle physics, split supersymmetry is a proposal for physics beyond the Standard Model. It was proposed separately in three papers. The first by James Wells in June 2003 in a more modest form that mildly relaxed the assumption about naturalness in the Higgs potential. In May 2004 Nima Arkani-Hamed and Savas Dimopoulos argued that naturalness in the Higgs sector may not be an accurate guide to propose new physics beyond the Standard Model and argued that supersymmetry may be realized in a different fashion that preserved gauge coupling unification and has a dark matter candidate. In June 2004 Gian Giudice and Andrea Romanino argued from a general point of view that if one wants gauge coupling unification and a dark matter candidate, that split supersymmetry is one amongst a few theories that exists.

The new light (~TeV) particles in Split Supersymmetry (beyond the Standard Models particles) are

The Lagrangian for Split Supersymmetry is constrained from the existence of high energy supersymmetry. There are five couplings in Split Supersymmetry: the Higgs quartic coupling and four Yukawa couplings between the Higgsinos, Higgs and gauginos. The couplings are set by one parameter, , at the scale where the supersymmetric scalars decouple. Beneath the supersymmetry breaking scale, these five couplings evolve through the renormalization group equation down to the TeV scale. At a future Linear collider, these couplings could be measured at the 1% level and then renormalization group evolved up to high energies to show that the theory is supersymmetric at an exceedingly high scale.

Superpartner

In particle physics, a superpartner (also sparticle) is a class of hypothetical elementary particles. Supersymmetry is one of the synergistic theories in current high-energy physics that predicts the existence of these “shadow" particles.When considering extensions of the Standard Model, the s- prefix from sparticle is used to form names of superpartners of the Standard Model fermions (sfermions), e.g. the stop squark. The superpartners of Standard Model bosons have an -ino (bosinos) appended to their name, e.g. gluino, the set of all gauge superpartners are called the gauginos.

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