String Unification of Particle Physics and Cosmology

String uniﬁcation of particle physics and cosmology

I. Antoniadis Albert Einstein Center, University of Bern LPTHE, Sorbonne Universit´e,CNRS Paris Session in Honor of Dimitri Nanopoulos’ Retirement Texas A&M University, College Station, 15 May 2019

I. Antoniadis (TexasA&M, 15 May 2019) 1 / 16 I. Antoniadis (TexasA&M, 15 May 2019) 2 / 16 I. Antoniadis (TexasA&M, 15 May 2019) 3 / 16 I. Antoniadis (TexasA&M, 15 May 2019) 4 / 16 A pleasant and fruitful collaboration

Met in California in 1985 one paper in collaboration with Costas Kounnas Intensive collaboration while fellow at CERN 1986-88 Phenomenology of four-dimensional strings eﬀective action, model building, ﬁnite temperature string cosmology and non-critical strings Continued a few years after my return in Paris Ongoing again recently ···

Here: Flipped SU(5) and linear dilaton background [10]

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15 papers found, 15 of them citeable (published or arXiv)

Citation summary results Citeable papers Published only Total number of papers analyzed: 15 15 Total number of citations: 2,681 2,681 Average citations per paper: 178.7 178.7 Breakdown of papers by citations: Renowned papers (500+) 2 2 Famous papers (250-499) 2 2 Very well-known papers (100-249) 5 5 Well-known papers (50-99) 2 2 Known papers (10-49) 3 3 Less known papers (1-9) 1 1 Unknown papers (0) 0 0

hHEP index [?] 14 14

I. Antoniadis (TexasA&M, 15 May 2019) 6 / 16 1 Noncompact Symmetries and Vanishing of the Cosmological Constant Ignatios Antoniadis (SLAC), C. Kounnas (UC, Berkeley), Dimitri V. Nanopoulos (CERN & UC, Santa Cruz). Published in Phys.Lett. 162B (1985) 309-316 Detailed record - Cited by 22 records

2 The Low-energy Effective Field Theory From Four-dimensional Superstrings Ignatios Antoniadis (CERN & Crete U.), John R. Ellis (CERN), E. Floratos (Crete U.), Dimitri V. Nanopoulos (Wisconsin U., Madison), T. Tomaras (Crete U.). Published in Phys.Lett. B191 (1987) 96-102 Detailed record - Cited by 87 records

3 On the Possibility of Avoiding Singularities by Dilaton Emission Ignatios Antoniadis, G.F.R. Ellis, John R. Ellis (CERN), C. Kounnas (LBL, Berkeley), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B191 (1987) 393-398 Detailed record - Cited by 9 records

4 Supersymmetric Flipped SU(5) Revitalized Ignatios Antoniadis, John R. Ellis (CERN), J.S. Hagelin (Maharishi U. of Management), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B194 (1987) 231-235 Detailed record - Cited by 542 records

5 Universality of the Mass Spectrum in Closed String Models Ignatios Antoniadis, John R. Ellis (CERN), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B199 (1987) 402-406 Detailed record - Cited by 50 records

I. Antoniadis (TexasA&M, 15 May 2019) 7 / 16

6 GUT Model Building with Fermionic Four-Dimensional Strings Ignatios Antoniadis (CERN), John R. Ellis (CERN & SLAC), J.S. Hagelin (Maharishi U. of Management), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B205 (1988) 459-465 Detailed record - Cited by 205 records

7 An Improved SU(5) x U(1) Model from Four-Dimensional String Ignatios Antoniadis, John R. Ellis (CERN), John S. Hagelin (Maharishi U. of Management), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B208 (1988) 209-215, Addendum: Phys.Lett. B213 (1988) 562 Detailed record - Cited by 218 records

8 Cosmological String Theories and Discrete Inflation Ignatios Antoniadis, C. Bachas, John R. Ellis (CERN), Dimitri V. Nanopoulos (Wisconsin U., Madison). Published in Phys.Lett. B211 (1988) 393-399 Detailed record - Cited by 296 records

9 An Expanding Universe in String Theory Ignatios Antoniadis, C. Bachas (Ecole Polytechnique), John R. Ellis (CERN), Dimitri V. Nanopoulos (Texas A-M). Published in Nucl.Phys. B328 (1989) 117-139 Detailed record - Cited by 297 records

10 The Flipped SU(5) x U(1) String Model Revamped Ignatios Antoniadis, John R. Ellis, J.S. Hagelin, Dimitri V. Nanopoulos (CERN). Published in Phys.Lett. B231 (1989) 65-74 Detailed record - Cited by 524 records

I. Antoniadis (TexasA&M, 15 May 2019) 8 / 16

11 A New Approach to Supersymmetry Breaking in Superstring Models Ignatios Antoniadis (Ecole Polytechnique), John R. Ellis (CERN), A.B. Lahanas (Athens U.), Dimitri V. Nanopoulos (Texas A-M). Published in Phys.Lett. B241 (1990) 24-30 Detailed record - Cited by 33 records

12 Comments on cosmological string solutions Ignatios Antoniadis (Ecole Polytechnique), C. Bachas, John R. Ellis (CERN), Dimitri V. Nanopoulos (Texas A-M & HARC, Woodlands). Published in Phys.Lett. B257 (1991) 278-284 Detailed record - Cited by 104 records

13 LEP data and the light gluino window Ignatios Antoniadis (Ecole Polytechnique), John R. Ellis (CERN), Dimitri V. Nanopoulos (Texas A-M & HARC, Woodlands). Published in Phys.Lett. B262 (1991) 109-112 Detailed record - Cited by 49 records

14 String threshold corrections and flipped SU(5) Ignatios Antoniadis (Ecole Polytechnique & CERN), John R. Ellis (CERN), R. Lacaze (Saclay), Dimitri V. Nanopoulos (Texas A-M & HARC, Woodlands & CERN). Published in Phys.Lett. B268 (1991) 188-196 Detailed record - Cited by 128 records

15 The Price of deriving the Standard Model from string Ignatios Antoniadis (Ecole Polytechnique & CERN), John R. Ellis (CERN), S. Kelley (Texas A-M & HARC, Woodlands), D.V. Nanopoulos (Texas A-M & HARC, Woodlands & CERN). Published in Phys.Lett. B272 (1991) 31-35 Detailed record - Cited by 117 records

I. Antoniadis (TexasA&M, 15 May 2019) 9 / 16 Connect string theory to the real world

Is it a tool for strong coupling dynamics or a theory of fundamental forces? If theory of Nature can it describe both particle physics and cosmology?

I. Antoniadis (TexasA&M, 15 May 2019) 10 / 16 Flipped SU(5): motivations

Framework: 4d heterotic strings in the 2d free-fermionic formulation describing the internal (6,22)-dim compactification with parameters the boundary conditions and corresponding coefficients IA-Bachas-Kounnas-Windey ’86, ABK ’86, AB ’87; Kawai-Lewellen-Tye ’86, ’87 Ideal for models of (supersymmetric) Grand Unification: all non-abelian gauge couplings equal at the string scale large rank (≤ 22) to embed the Standard Model or GUT extensions gauge group representations: fundamental and antisymmetric However no massless adjoints to break the GUT group Flipped SU(5): a minimal variation of SU(5) to bypass the problem

I. Antoniadis (TexasA&M, 15 May 2019) 11 / 16 Flipped SU(5): the model

matter representations: exchange dc and uc between 5¯ and 10 => ¯ c c c c 5¯f = (u , L), 10F = [Q, d , ν ], l , extra U(1): SU(5) × U(1) ¯ Higgs representations: 10H + 10H¯, 5h + 5h¯ SU(5) × U(1) → SU(3) × SU(2) × U(1) via hHi = hH¯i= 6 0 along νc , ν¯c H H¯ ¯ c 5h = (dh, h2), 5h¯ = (dh , h1) contain the electroweak higges h1, h2 General superpotential invariant under H → −H in presence of singlets φ

c 3 W = λd FFh+λuF f¯h¯+λe l f¯ h+λ4HHh+λ5H¯H¯h¯+λ6F H¯φ+λ7hh¯φ+λ8φ λ , λ => doublet-triplet splitting with GUT masses d dc + d¯ d¯c 4 5 h H h¯ H¯

λu => mu = mν c however see-saw mechanism with ν and φ via λ6 and λ8

I. Antoniadis (TexasA&M, 15 May 2019) 12 / 16 Flipped SU(5): properties of the model

gauge coupling uniﬁcation

1 8 2 15α1 Y = Q5 + Q1 => sin θw = 15 5 16α1 + 24α5 2 3 SU(5) × U(1) embedded in SO(10) => α1 = α5 => sin θw = 8 Yukawa couplings and fermion masses only one generation has tree level couplings

λt = g5 => mt ∼< 190 GeV the rest of the couplings via VEVs of singlets `ala Froggatt Nielsen −2 due to an anomalous U(1) D-term at a scale of order 10 × Mstring

I. Antoniadis (TexasA&M, 15 May 2019) 13 / 16 Cosmological string solutions

string frame: ﬂat metric and dilaton linear in time φ = −QX 0

exact conformal ﬁeld theory: X 0 acquires a 2d background charge 2iQ changing its central charge to 1 − 12Q2

−2φ Einstein frame: gµν = e ηµν => linear expanding Universe

2 2 2 2 1 QX 0 ds = −dt + t d~x in FRW coordinates t = Q e and φ = − ln(Qt) solution valid for any dimension In d = 4 one can also add space curvature κ ≥ 0 replacing xi by a SU(2) WZW model of level k √ describing a 3-metric on S3 and an axion a = 2Q2 κt dr 2 ds2 = −dt2 + t2 + r 2(dθ2 + sin2 θdϕ2) κ = 1/(2Q2k) 1 − κr 2

I. Antoniadis (TexasA&M, 15 May 2019) 14 / 16 Linear dilaton background

Non-critical string 6 central charge: c = 4 − 12Q2 − + c = 26 (bosonic string) k + 2 I 4 cˆ = 4 − 8Q2 − +c ˆ = 10 (superstring) k + 2 I

=> more internal dimensions than critical stringc ˆI > 6 Q = 0 => static Einstein universe Q 6= 0 => R = 6(1 + κ)/t2 initial singularity at t = 0 but string propagation well deﬁned study of string propagation in the linear in time dilaton background spectrum, partition function, amplitudes using screening operators due to the background charge

I. Antoniadis (TexasA&M, 15 May 2019) 15 / 16 Conclusions

My collaboration with Dimitri: Great physics, continuous ﬂow of ideas and great fun

ΧΡΟΝΙΑ ΠΟΛΛΑ ΔΗΜΗΤΡΗ

THANK YOU FOR OUR COLLABORATION

I. Antoniadis (TexasA&M, 15 May 2019) 16 / 16