Sigma (disambiguation)

Sigma is a letter of the Greek alphabet.

Sigma may also refer to:

Companies

• Sigma TV, a television channel in Cyprus
• Sigma Company, an Australian pharmaceutical company
• Sigma Corporation, a Japanese camera and lens manufacturer
• Sigma Company Limited, a Hungarian debt management company
• Sigma-Aldrich, an American chemical company
• Sigma Designs, Inc., a US semiconductor manufacturer
• SIGMA (verification service), Nielsen Media Research's tracking system for videos
• Sigma Sport, a German manufacturer of electronic sports equipment
• Sigma AB, Swedish IT consultancy company
• Telkomsigma or Sigma Cipta Caraka, an Indonesian ICT business solution provider

Mathematics

• Summation operator forming a series in mathematics Σ
• Standard deviation in statistics σ
• Divisor function in number theory σ
• Sigma-algebra (σ-algebra, σ-field) in set theory
• A busy beaver function in computability theory Σ
• $\Sigma^0_n$ or $\Sigma^1_n$, sets in the analytical hierarchy
• $\Sigma^P_i$, a set in the polynomial hierarchy
• Harish-Chandra's σ function
• Weierstrass sigma function

Science

• Stefan-Boltzmann constant of radiation in physics σ
• Sigma factor of RNA polymerase in biology σ
• In the Hammett equation, the electronic substituent constant σ for activation of substituted arenes
• Sigma baryon, a class of baryons in particle physics
• Pauli matrices in quantum physics
• Cross section σ in physics
• Sigma bond in chemistry σ
• Sigma receptor, a subtype of opioid receptor
• Electrical conductivity, a measure of a material's ability to conduct electricity σ
• Stress (mechanics), the force per unit area applied by internal forces of a material σ

Products

• Sigma (sailplane)
• Mitsubishi Sigma (disambiguation)
• GM Sigma platform, a mid-size car automobile platform from General Motors Corporation
• Smith & Wesson Sigma, a firearm
• Sigma Guitars
• The SDS Sigma series of computers from Scientific Data Systems

Video games

• Sigma (Mega Man X), the main villain in the Mega Man X video game series
• Ninja Gaiden Sigma, a PlayStation 3 title in the Ninja Gaiden video game series
• Sigma, a character in the BioShock 2 downloadable content pack "Minerva's Den"
• Sigma Harmonics, a video game

Other

• Sigma (couch), an ancient Roman couch used for banquets
• Sigma, Capiz, a municipality in the Philippines
• The Six Sigma quality management program
• Ood Sigma, a fictional character from the Doctor Who series
• SK Sigma Olomouc, Czech association football team
• Space City Sigma, a 1980s Indian science fiction TV series
• Sigma class corvette, a naval ship