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Title: The eejj excess signal at the LHC and constraints on leptogenesis

Abstract

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy E{sub 6}-based models to investigate if they can explain both the recently detected excess eejj signal at CMS and leptogenesis. The eejj excess can be explained from the decay of the right-handed gauge bosons (W{sub R}) with mass ∼ TeV in certain variants of the LRSM (with g{sub L}≠g{sub R}). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the W{sub R} mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However, certain lepton number violating scattering processes involving the right-handed Higgs triplet and the right-handed neutrinos can stay in equilibrium till the electroweak phase transition and can washout the lepton asymmetry generated in the resonant leptogenesis scenario for mass range of W{sub R} as indicated by the CMS excess signal. Thus in such a scenario one needs to invoke post-sphaleron baryogenesis to explain the observed baryon asymmetry of the universe. Next, we consider three effective low energy subgroups of the superstring inspired E{sub 6} model having a number of additional exotic fermionsmore » which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of E{sub 6} too cannot explain both the eejj excess signal and leptogenesis simultaneously.« less

Authors:
 [1];  [1];  [2]; ;  [1]
  1. Physical Research Laboratory,Navrangpura, Ahmedabad 380 009 (India)
  2. (India)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22458375
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 09; Other Information: PUBLISHER-ID: JCAP09(2015)035; OAI: oai:repo.scoap3.org:11780; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; BARYONS; CERN LHC; CMS DETECTOR; HIGGS BOSONS; LEPTON NUMBER; NEUTRINOS; PARTICLE PRODUCTION; PHASE TRANSFORMATIONS; SCATTERING; SIGNALS; SUPERSTRING MODELS; SUPERSYMMETRY; TEV RANGE; TRIPLETS; UNIVERSE; YUKAWA POTENTIAL

Citation Formats

Dhuria, Mansi, Hati, Chandan, Indian Institute of Technology Gandhinagar,Chandkheda, Ahmedabad 382 424, Rangarajan, Raghavan, and Sarkar, Utpal. The eejj excess signal at the LHC and constraints on leptogenesis. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/09/035.
Dhuria, Mansi, Hati, Chandan, Indian Institute of Technology Gandhinagar,Chandkheda, Ahmedabad 382 424, Rangarajan, Raghavan, & Sarkar, Utpal. The eejj excess signal at the LHC and constraints on leptogenesis. United States. doi:10.1088/1475-7516/2015/09/035.
Dhuria, Mansi, Hati, Chandan, Indian Institute of Technology Gandhinagar,Chandkheda, Ahmedabad 382 424, Rangarajan, Raghavan, and Sarkar, Utpal. Fri . "The eejj excess signal at the LHC and constraints on leptogenesis". United States. doi:10.1088/1475-7516/2015/09/035.
@article{osti_22458375,
title = {The eejj excess signal at the LHC and constraints on leptogenesis},
author = {Dhuria, Mansi and Hati, Chandan and Indian Institute of Technology Gandhinagar,Chandkheda, Ahmedabad 382 424 and Rangarajan, Raghavan and Sarkar, Utpal},
abstractNote = {We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy E{sub 6}-based models to investigate if they can explain both the recently detected excess eejj signal at CMS and leptogenesis. The eejj excess can be explained from the decay of the right-handed gauge bosons (W{sub R}) with mass ∼ TeV in certain variants of the LRSM (with g{sub L}≠g{sub R}). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the W{sub R} mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However, certain lepton number violating scattering processes involving the right-handed Higgs triplet and the right-handed neutrinos can stay in equilibrium till the electroweak phase transition and can washout the lepton asymmetry generated in the resonant leptogenesis scenario for mass range of W{sub R} as indicated by the CMS excess signal. Thus in such a scenario one needs to invoke post-sphaleron baryogenesis to explain the observed baryon asymmetry of the universe. Next, we consider three effective low energy subgroups of the superstring inspired E{sub 6} model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of E{sub 6} too cannot explain both the eejj excess signal and leptogenesis simultaneously.},
doi = {10.1088/1475-7516/2015/09/035},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 09,
volume = 2015,
place = {United States},
year = {Fri Sep 11 00:00:00 EDT 2015},
month = {Fri Sep 11 00:00:00 EDT 2015}
}
  • We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy E{sub 6}-based models to investigate if they can explain both the recently detected excess eejj signal at CMS and leptogenesis. The eejj excess can be explained from the decay of the right-handed gauge bosons (W{sub R}) with mass ∼ TeV in certain variants of the LRSM (with g{sub L}≠ g{sub R}). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the W{sub R} mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the contextmore » of the LRSM for relatively large Yukawa couplings. However, certain lepton number violating scattering processes involving the right-handed Higgs triplet and the right-handed neutrinos can stay in equilibrium till the electroweak phase transition and can washout the lepton asymmetry generated in the resonant leptogenesis scenario for mass range of W{sub R} as indicated by the CMS excess signal. Thus in such a scenario one needs to invoke post-sphaleron baryogenesis to explain the observed baryon asymmetry of the universe. Next, we consider three effective low energy subgroups of the superstring inspired E{sub 6} model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of E{sub 6} too cannot explain both the eejj excess signal and leptogenesis simultaneously.« less
  • If the seesaw mechanism is responsible for neutrino masses, an important question for physics beyond the standard model is the scale of B-L symmetry breaking responsible for the right-handed neutrino masses. Assuming this scale to be in the TeV range makes it accessible at the LHC. Here we discuss the compatibility of low-scale B-L symmetry with leptogenesis as the mechanism for understanding the origin of matter, and whether a direct collider probe of this mechanism is possible. We find that successful leptogenesis implies a lower bound M{sub Z}'>=2.6 TeV, which is in the LHC reach. Moreover, it may be possiblemore » to directly probe leptogenesis via a difference in the number of positive and negative like-sign dilepton events originating from right-handed neutrino decays.« less
  • We explore direct collider probes of the resonant leptogenesis mechanism for the origin of matter. We work in the context of theories where the standard model (SM) is extended to include an additional gauged U(1) symmetry broken at the TeV scale, and where the light neutrinos obtain mass through a type I seesaw at this scale. The CP asymmetry that generates the observed matter-antimatter asymmetry manifests itself in a difference between the number of positive and negative like-sign dileptons N(l{sup +}l{sup +})-N(l{sup -}l{sup -}) that arise in the decay of the new Z{sup '} gauge boson to two right-handed neutrinosmore » N, and their subsequent decay to leptons. The relatively low efficiency of resonant leptogenesis in this class of models implies that the CP asymmetry, {epsilon}, is required to be sizable, i.e., of order one. In particular, from the sign of the baryon asymmetry of the Universe, an excess of antileptons is predicted. We identify the domains in M{sub Z}{sup '}-M{sub N} space where such a direct test is possible and find that with 300 fb{sup -1} of data and no excess found, the LHC can set the 2{sigma} exclusion limit {epsilon} < or approx. 0.22.« less
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