Models based on Universal Extra Dimensions predict Kaluza-Klein (KK) excitations of all Standard Model (SM) particles. We examine the pair production of KK excitations of top-and bottom-quarks at the Large Hadron Collider. Once produced, the KK top/bottom quarks can decay to b-quarks, leptons and the lightest KK-particle, γ 1 , resulting in 2 b-jets, two opposite sign leptons and missing transverse momentum, thereby mimicing top-pair production. We show that, with a proper choice of kinematic cuts, an integrated luminosity of 100 fb -1 would allow a discovery for an inverse radius upto R -1 = 750GeV. © 2010 SISSA, Trieste, Italy.

ANINDYA DATTA

Physics

D CHOUDHURY

K GHOSH

Fulltext

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

Journal of High Energy Physics

In universal extra-dimensional models a conserved Z2 parity ensures the stability of the lightest Kaluza-Klein particle, a potential dark-matter candidate. Boundary-localized kinetic terms, in general, do not preserve this symmetry. We examine, in the presence of such terms, the single production of Kaluza-Klein excitations of the neutral electroweak gauge bosons and their decay to zero-mode fermion-antifermion pairs. We explore how experiments at the Large Hadron Collider at CERN can constrain the boundary-localized kinetic terms for different choices of the compactification radius. © 2013 American Physical Society.

Physical Review D - Particles, Fields, Gravitation and Cosmology

Universal extra-dimensional models with boundary localized kinetic terms: Probing at the LHC

In universal extra-dimensional models a conserved Z(2) parity ensures the stability of the lightest Kaluza-Klein particle, a potential dark-matter candidate. Boundary-localized kinetic terms, in general, do not preserve this symmetry. We examine, in the presence of such terms, the single production of Kaluza-Klein excitations of the neutral electroweak gauge bosons and their decay to zero-mode fermion-antifermion pairs. We explore how experiments at the Large Hadron Collider at CERN can constrain the boundary-localized kinetic terms for different choices of the compactification radius. DOI: 10.1103/PhysRevD.87.076002

Physical Review D

The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed. © SISSA 2010.

Search for Higgs bosons of the Universal Extra Dimensions at the Large Hadron Collider

Some of the cleanest signals for new physics in the early runs of the LHC will involve strongly produced particles which give rise to multiple leptons by undergoing cascade decays through weakly interacting states to stable particles. Some of the most spectacular final states will involve three or more leptons, multiple jets and generally missing energy-momentum as well. A triad of the most interesting models of new physics which induce such signals is known to consist of (i) supersymmetry with R-parity conservation, (ii) a universal extra dimension with conservation of KK-parity, and (iii) little Higgs models with conserved T-parity. Similar signals could also arise if the standard model is augmented with a fourth sequential generation of heavy fermions. We study all these possibilities and show that a judiciously chosen set of observables, critically involving the number of identifiable jets and leptons, can collectively provide distinct footprints for each of these models. In fact, simple pairwise correlation of such observables can enable unambiguous identification of the underlying model, even with a relatively small data sample.

Multijet discriminators for new physics in leptonic signals at the LHC

The minimal universal extra dimension (mUED) model respects the Kaluza-Klein (KK) parity (-1)n, where n is the KK number. However, it is possible to have interactions located at only one of the two fixed points of the S1/Z2 orbifold. Such asymmetric interactions violate the KK parity. This kills the cold dark matter component of UED but also removes the upper bound on the inverse compactification radius, and thus nonobservation of the KK excitations even at the Large Hadron Collider does not necessarily invalidate the model. Apart from the decay of the lightest n=1 KK excitation, this leads to collider signals which are markedly different from those in the mUED scenario. The phenomenological consequences of such KK-parity violating terms are explored. © 2009 The American Physical Society.

Universal extra dimension: Violation of Kaluza-Klein parity

The upper limit on the mass of the lightest CP-even neutral Higgs in the minimal supersymmetric standard model is around 135 GeV for soft supersymmetry breaking masses in the 1 TeV range. We demonstrate that this upper limit may be sizably relaxed if supersymmetry is embedded in extra dimensions. We calculate, using the effective potential technique, the radiative corrections to the lightest Higgs mass induced by the Kaluza-Klein towers of quarks and squarks with one and two compactified directions. We observe that the lightest Higgs may comfortably weigh around 200 GeV (300 GeV) with one (two) extra dimension(s). © 2007 Elsevier B.V. All rights reserved.

Nuclear Physics B

Extra-dimensional relaxation of the upper limit of the lightest supersymmetric neutral Higgs mass

In a five-dimensional model with one universal extra dimension, signals for a pair of n = 1 Kaluza-Klein excitations could be easily observed at a future e(+)e(-) collider if the process in question is kinematically allowed. However, these signals would prove difficult to distinguish from those predicted in other models, such as those with an extended gauge symmetry or supersymmetry. A much better power of discrimination is provided by the fact that the same machine could also produce the n = 2 gauge bosons gamma(2) and Z(2) as resonances in fermion pair production without any upgrade in the collision energy root s. Assuming a fixed root s-as is expected at upcoming e(+)e(-) machines-we investigate the role of beam radiation in helping to excite such resonances through radiative returns. We then show how these resonances could yield unambiguous signals for a universal extra dimension, if taken in conjunction with the production of Z(1) pairs, identified by their decays to leptons and missing transverse energy.

Journal	Data powered by TypesetJournal of High Energy Physics
Publisher	Data powered by TypesetSPRINGER
ISSN	1126-6708
Open Access	No