Space Anisotropy Search at Colliders
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EMENTARY PARTICLES AND FIELDS Theory
Space Anisotropy Search at Colliders I. S. Karpikov*, D. A. Tlisov** , and D. V. Kirpichnikov*** Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, 117312 Russia Received October 24, 2017
Abstract—In the framework of model with Lorentz violation (LV) we discuss a physical observables for q q¯ pair production at lepton–lepton colliders and describe the experimental signal to be detected. We obtain a conservative limits on Lorentz-violating dimensionless coupling for quark sector from LEP data. We also make a phenomenological prediction for LV model at the future lepton collider. DOI: 10.1134/S1063778818020114
1. INTRODUCTION The problem of space-time anisotropy is a great challenge of high energy physics. The attempts to measure the space anisotropy for a relatively low energy scale are widely performed by an astrophysical experimental searches. Nevertheless, the ability to search fundamental properties of space-time on a high energy scales appears with LHC launching. A violation of Lorentz invariance is one of the possible reason of space anisotropy. There are various self-consistent setups of quantum gravity which admit the violation of Lorentz invariance: a models of quantum loop gravity [1, 2], string model setups [3, 4], a models of Horava-Lifshitz with extra spatial derivatives [5–7], the models of the analogue gravity [8]. The most general Lorentz-violating (LV) Lagrangian with gauge invariant renormalizable terms was performed by [9, 10] for the particles of standard model (SM). The former framework is known as Standard-Model Extension (SME) of Alan Kosteletsky. The current constraints on SME parameters are presented in [11]. In particular, the limits for leptons have been set at the level of 10−6 −10−20 . A very recent result [12] claims that CP T -even coefficients for LV in the quark sector (e.g. for u and d quarks) can be bounded at the level about 10−5 −10−6 from HERA experimental data on deep inelastic scattering (DIS) of e− p. A framework of SME has been explored carefully also in the context of Tevatron collider phenomenology. In particular Ref. [13] provides the bounds on CP T -even LV couplings of top quark from dependence of the tt¯ production cross-section on sideral time as the orientation of the D0 detector *
E-mail: [email protected] E-mail: [email protected] *** E-mail: [email protected] **
changes with the rotation of the Earth. Test of CP T odd symmetry violation for B-mesons was performed in Refs. [14, 15]. However the limits on CP T -even LV coupling (cQ(U,D) )ZZAB for quarks hasn’t been obtained yet. In the present paper we discuss a possible implication of the SME phenomenology for quark sector at a lepton–lepton colliders. Namely, we calculate the production cross-section of q q¯ pair via γ and Z 0 boson for the SME couplings that affect the quark field. The paper is organized as follows. In Sec. 2 we consider general Lagrangian of the SME and perform LV couplings of quarks to be constrained by collider experiment. In Sec. 3 w
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