Quantum gravity or string compactification can lead to effective dimension-5 operators in Grand Unified Theories which modify the gauge kinetic terms. We exhaustively discuss the group-theoretic nature of such operators for the popular SU(5), SO(10), and E(6) models. In particular, for SU(5) only a Higgs in the 200 representation can help bring the couplings to unification below the Planck scale and in consistency with proton decay limits while for a supersymmetric version 24, 75, or 200 representations are all acceptable. The results also have a direct application in non-universality of gaugino masses in a class of supersymmetric models where identical group-theoretic features obtain. © 2009 Elsevier B.V. All rights reserved.

J CHAKRABORTTY

A RAYCHAUDHURI

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University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

Dimension-5 corrections to the gauge kinetic term of grand unified theories may capture effects of quantum gravity or string compactification. Such operators modify the usual gauge coupling unification prediction in a calculable manner. Here we examine SU(5), SO(10), and E(6) grand unified theories in the light of all such permitted operators and calculate the impact on the intermediate scales and the unification program. We show that in many cases at least one intermediate scale can be lowered to even 1-10 TeV, where a neutral Z′ and possibly other states are expected. © 2010 The American Physical Society.

Journal	Data powered by TypesetPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Publisher	Data powered by TypesetELSEVIER SCIENCE BV
ISSN	0370-2693
Open Access	Yes