16th Marcel Grossmann Meeting- MG16 1 Gravitational Anomalies, Dark Matter and Leptogenesis Sarben Sarkar Dept. of Physics, Kingโs College London, UK References: M de Cesare, N E Mavromatos, S Sarkar, Eur. Phys. J C 75 514 (2015) T Bossingham, N E Mavromatos, S Sarkar, Eur Phys J C 78 113 (2018) T Bossingham, N E Mavromatos and S Sarkar, Eur. Phys. J. C 79 50 (2019) N E Mavromatos and S Sarkar, Universe 5, no. 1:5 https://doi.org/10.3390/5010005 N E Mavromatos and S Sarkar, Eur. Phys. C 80 558 (2020) J Ellis, N E Mavromatos and S Sarkar, Phys. Lett. B 725 407 (2013)
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Gravitational Anomalies, Dark Matter and Leptogenesis
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16th Marcel Grossmann Meeting-MG16 1
Gravitational Anomalies, Dark Matter and Leptogenesis
Sarben SarkarDept. of Physics, Kingโs College London, UK
References: M de Cesare, N E Mavromatos, S Sarkar, Eur. Phys. J C 75 514 (2015)T Bossingham, N E Mavromatos, S Sarkar, Eur Phys J C 78 113 (2018)T Bossingham, N E Mavromatos and S Sarkar, Eur. Phys. J. C 79 50 (2019)N E Mavromatos and S Sarkar, Universe 5, no. 1:5 https://doi.org/10.3390/5010005N E Mavromatos and S Sarkar, Eur. Phys. C 80 558 (2020)J Ellis, N E Mavromatos and S Sarkar, Phys. Lett. B 725 407 (2013)
Bosonic gravitational multiplet of strings consists of a โข graviton, ๐๐๐โข spin 0 scalar field ๐ฝ the dilatonโข spin 1 antisymmetric gauge field ๐ฉ๐๐ with gauge invariant
โข Model leads to acceptable leptogenesis at thetree level, owing to Majorana nature of ๐ต which is taken to be very heavyโข Freeze out of N at ๐ป = ๐ป๐ซ.โข B-L conservation converts ๐ซ๐ณ to ๐ซ๐ฉโข ๐ฉ๐ = ๐๐๐โข Non-zero ๐ฉ๐ backgroundโข The underlying torsion connects this model
where ๐ = ๐๐ต๐ป, and ๐ ๐ = ๐ or ๐ ๐ = ๐,๐.
โข Gravitational background๐๐๐ = ๐, ๐๐๐= โ๐๐ ๐ ๐น๐๐, space Cartesianโข Generation of lepton asymmetry due to CP and CPTV
tree-level decays:โข ๐ต โ ๐,๐8, ๐๐๐ channel 1โข ๐ต โ ๐8๐,, ๐๐๐ channel 2where ๐ยฑ are charged leptons, ๐ ๐ are active (anti)neutrinosโข For ๐ฝ โ ๐ the decay rates of ๐ต differ for channels 1
and 2 leading to a lepton asymmetry which freezes out at ๐ป๐ซ.
For ๐~๐๐,๐ and ๐๐ต = ๐ถ ๐๐๐ ๐ป๐๐ฝ and ๐ฉ๐~๐. ๐๐ด๐๐ฝ forphenomenologically acceptable leptogenesis to occur at
๐ป๐ซ~๐๐๐ป๐๐ฝ
Gravitational axions as Dark Matter I
l Peccei and Quinn solution of strong CP problemโ โ ๐ ๐ ๐ถ๐
๐๐ ๐ป๐ ๐ฎ โง ๐ฎ
where the ๐ vacuum parameter becomes a field and ๐ฎ is the QCD gauge field 2-form (R D Peccei and H R. Quinn, Phys Rev. Lett 38 1440 (1977))
Standard procedure: select a vacuum with ๐ ๐ = ๐ with a fluctuation a ๐
l Move away from Goldstone axion a ๐ฅ ๐ญ๐จ gravitational axion b ๐ whose couplings are determined by the Planck scale
l Classical torsionful spacetime manifold characterised by:torsion 2-from
with ๐ and ๐ the gauge connection 1-forms for ๐ผ ๐ ๐๐ and SU(3)c,๐ธ = ๐ธ๐๐๐ and ๐ธ๐๐=
๐๐๐ธ๐, ๐ธ๐ .
Equation of motion with respect to ๐๐๐ gives that the torsion satisfies๐ฃ๐๐๐ = โ ๐ฟ๐
๐๐บ๐๐๐๐ โ๐ ๐ฑ ๐๐ ๐
where ๐ฑ ๐๐ ๐ = ๐๐ฟ๐๐ธ๐ ๐ธ๐๐ฟ๐. (See also R Utiyama, Phys Rev 101, 1597 (1956); T W B Kibble, J Math Phys 2 212(1961);D W Sciama, Monthly Not. Roy, Astr. Soc. 113 34 (1953); F W Hehl, Gen Rel Grav 4 333 (1973); E Cartan, Riemannian Geometry in an Orthogoanl Frame (World Scientific, 2001), O Casillo-Feliso;a et al. Phys Rev D 91 085017 (2015) )
Anomalies(cf S Basilakos et al. PRD 101 045001 (2020)
M J Duncan, N Kaloper, K A Olive, Nucl. Phys. B387 215 (1992))
โข The gravitational anomaly (GA) may not be cancelledin the early universe in a quantum theory of gravity.
โข The gauge anomaly though can be designed to cancel for asuitable GUT theory. Anomaly cancellation is necessary for the theories to be renormalizable.
โข GA implies breakdown of diffeomorphism lnvarianceand hence local Lorentz invariance (LIV)
โข LIV allows a non-zero ๐ฝrequired for our leptogenesis model
โข The Kalb-Ramond axion could play the role of a QCD axionand so be axionic dark matter (M Lattanzi and S Mercuri, Phys Rev D81 125015 (2010))