The CKM unitarity problem: a trace of new physics at the TeV scale?
Tóm tắt
After the recent high precision determinations of $$V_{us}$$ and $$V_{ud}$$, the first row of the CKM matrix shows more than $$4\sigma $$ deviation from unitarity. Two possible scenarios beyond the Standard Model can be investigated in order to fill the gap. If a 4th non-sequential quark $$b'$$ (a vector-like weak isosinglet) participates in the mixing, with $$\vert V_{ub'} \vert \sim 0.04$$, then its mass should be no more than 6 TeV or so. A different solution can come from the introduction of the gauge horizontal family symmetry $$SU(3)_\ell $$ acting between the lepton families and spontaneously broken at the scale of about 6 TeV. Since the gauge bosons of this symmetry contribute to muon decay in interference with Standard Model, the Fermi constant is slightly smaller than the muon decay constant so that unitarity is recovered. Also the neutron lifetime problem, that is about $$4\sigma $$ discrepancy between the neutron lifetimes measured in beam and trap experiments, is discussed in the light of the these determinations of the CKM matrix elements.
Tài liệu tham khảo
J.C. Hardy, I.S. Towner, Phys. Rev. C 91(2), 025501 (2015). arXiv:1411.5987 [nucl-ex]
J. Hardy, I.S. Towner, PoS CKM 2016, 028 (2016)
V. Tishchenko et al., [MuLan Collaboration], Phys. Rev. D 87(5), 052003 (2013). arXiv:1211.0960 [hep-ex]
M. Moulson, PoS CKM 2016, 033 (2017). arXiv:1704.04104 [hep-ex]
M. Tanabashi et al., [Particle Data Group], Phys. Rev. D 98(3), 030001 (2018)
S. Aoki et al., [FLAG], Eur. Phys. J. C 77(2), 112 (2017). arXiv:1607.00299 [hep-lat]
W.J. Marciano, A. Sirlin, Phys. Rev. Lett. 96, 032002 (2006). arXiv:hep-ph/0510099
C.Y. Seng, M. Gorchtein, H.H. Patel, M.J. Ramsey-Musolf, Phys. Rev. Lett. 121(24), 241804 (2018). arXiv:1807.10197 [hep-ph]
A. Bazavov et al., [Fermilab Lattice and MILC Collaborations], Phys. Rev. D 99(11), 114509 (2019). arXiv:1809.02827 [hep-lat]
S. Aoki et al., [Flavour Lattice Averaging Group]. arXiv:1902.08191 [hep-lat]
M. Di Carlo, D. Giusti, V. Lubicz et al., Phys. Rev. D 100(3), 034514 (2019). arXiv:1904.08731 [hep-lat]
A. Czarnecki, W.J. Marciano, A. Sirlin, Phys. Rev. D 100(7), 073008 (2019). arXiv:1907.06737 [hep-ph]
E. Kuflik, Y. Nir, T. Volansky, Phys. Rev. Lett. 110(9), 091801 (2013). arXiv:1204.1975 [hep-ph]
B. Belfatto, Z. Berezhiani (in preparation)
L. Lavoura, J.P. Silva, Phys. Rev. D 47, 1117 (1993)
Z.G. Berezhiani, Phys. Lett. B 129, 99 (1983)
Z.G. Berezhiani, Phys. Lett. B 150, 177 (1985)
Z.G. Berezhiani, J.L. Chkareuli, JETP Lett. 35, 612 (1982)
Z.G. Berezhiani, J.L. Chkareuli, Sov. J. Nucl. Phys. 37, 618 (1983)
Z.G. Berezhiani, J.L. Chkareuli, Sov. J. Nucl. Phys. 52, 383 (1990)
Z.G. Berezhiani, M.Y. Khlopov, Z. Phys. C 49, 73 (1991)
Z.G. Berezhiani, M.Y. Khlopov, Sov. J. Nucl. Phys. 51, 739 (1990)
Z.G. Berezhiani, M.Y. Khlopov, Sov. J. Nucl. Phys. 52, 60 (1990)
Z. Berezhiani, A. Rossi, Nucl. Phys. B 594, 113 (2001). arXiv:hep-ph/0003084
S.F. King, G.G. Ross, Phys. Lett. B 574, 239 (2003). arXiv:hep-ph/0307190
Z. Berezhiani, F. Nesti, JHEP 0603, 041 (2006). arXiv:hep-ph/0510011
P. Binetruy, S. Lavignac, P. Ramond, Nucl. Phys. B 477, 353 (1996). arXiv:hep-ph/9601243
E. Dudas, C. Grojean, S. Pokorski, C.A. Savoy, Nucl. Phys. B 481, 85 (1996). arXiv:hep-ph/9606383
Z. Berezhiani, Z. Tavartkiladze, Phys. Lett. B 396, 150 (1997). arXiv:hep-ph/9611277
Z. Berezhiani, Z. Tavartkiladze, Phys. Lett. B 409, 220 (1997). arXiv:hep-ph/9612232
B. Belfatto, Z. Berezhiani, Eur. Phys. J. C 79(3), 202 (2019). arXiv:1812.05414 [hep-ph] (see also B. Belfatto, PoS EPS -HEP2017, 660 (2017))
Z. Berezhiani, G.R. Dvali, Phys. Lett. B 450, 24 (1999). arXiv:hep-ph/9811378
A. Pich, Prog. Part. Nucl. Phys. 75, 41 (2014). arXiv:1310.7922 [hep-ph]
M. Gonzalez-Alonso, O. Naviliat-Cuncic, N. Severijns, Prog. Part. Nucl. Phys. 104, 165 (2019). arXiv:1803.08732 [hep-ph]
I.S. Towner, J.C. Hardy, Rep. Prog. Phys. 73, 046301 (2010)
A. Czarnecki, W.J. Marciano, A. Sirlin, Phys. Rev. Lett. 120, 202002 (2018). arXiv:1802.01804 [hep-ph]
D. Mund et al., Phys. Rev. Lett. 110, 172502 (2013). arXiv:1204.0013 [hep-ex]
M.A.-P. Brown et al., Phys. Rev. C 97(3), 035505 (2018). arXiv:1712.00884 [nucl-ex]
B. Märkisch et al., Phys. Rev. Lett. 122(24), 242501 (2019). arXiv:1812.04666 [nucl-ex]
A. Serebrov, A. Fomin, Phys. Procedia 17, 19 (2011)
G.L. Greene, P. Geltenbort, Sci. Am. 314, 36 (2016)
W. Mampe et al., JETP Lett. 57, 82 (1993)
A.P. Serebrov et al., Phys. Lett. B 605, 72 (2005). arXiv:nucl-ex/0408009
A.P. Serebrov et al., Phys. Rev. C 78, 035505 (2008). arXiv:nucl-ex/0702009 [NUCL-EX]
A. Pichlmaier et al., Phys. Lett. B 693, 221 (2010)
A. Steyerl et al., Phys. Rev. C 85, 065503 (2012)
S. Arzumanov et al., Phys. Lett. B 745, 79 (2015)
A.P. Serebrov et al., Phys. Rev. C 97(5), 055503 (2018). arXiv:1712.05663 [nucl-ex]
V.F. Ezhov et al., JETP 107, 11 (2018). arXiv:1412.7434 [nucl-ex]
R.W. Pattie Jr. et al., Science 360(6389), 627 (2018). arXiv:1707.01817 [nucl-ex]
J. Byrne et al., Europhys. Lett. 33, 187 (1996)
A.T. Yue et al., Phys. Rev. Lett. 111(22), 222501 (2013). arXiv:1309.2623 [nucl-ex]
Z. Berezhiani, L. Bento, Phys. Rev. Lett. 96, 081801 (2006). arXiv:hep-ph/0507031
Z. Berezhiani, L. Bento, Phys. Lett. B 635, 253 (2006). arXiv:hep-ph/0602227
Z. Berezhiani, Eur. Phys. J. C 64, 421 (2009). arXiv:0804.2088 [hep-ph]
Z. Berezhiani, Eur. Phys. J. C 79(6), 484 (2019). arXiv:1807.07906 [hep-ph]
Z. Berezhiani, LHEP 158, 1 (2019). https://doi.org/10.31526/LHEP.1.2019.118. arXiv:1812.11089 [hep-ph]
A. Anselm, Z. Berezhiani, Nucl. Phys. B 484, 97 (1997). arXiv:hep-ph/9605400
Z. Berezhiani, A. Rossi, Nucl. Phys. Proc. Suppl. 101, 410 (2001). arXiv:hep-ph/0107054
G. D’Ambrosio, G.F. Giudice, G. Isidori, A. Strumia, Nucl. Phys. B 645, 155 (2002). arXiv:hep-ph/0207036
Z. Berezhiani, Phys. Lett. B 417, 287 (1998)
Z. Berezhiani, Int. J. Mod. Phys. A 19, 3775 (2004)
Z. Berezhiani, Through the looking-glass: Alice’s adventures in mirror world. In eds. by M. Shifman et al. I. Kogan Memorial Volume From Fields to Strings, Circumnavigating Theoretical Physics, vol 3 (World Scientific, 2005), pp. 2147–2195. arXiv:hep-ph/0508233
Z. Berezhiani, Eur. Phys. J. ST 163, 271 (2008)
R. Cerulli et al., Eur. Phys. J. C 77(2), 83 (2017). arXiv:1701.08590 [hep-ex]
A. Addazi et al., Eur. Phys. J. C 75(8), 400 (2015). arXiv:1507.04317 [hep-ex]