We propose a model that realizes a semivisible dark photon which can contribute to the anomalous magnetic moment (<math><mi>g</mi><mo>−</mo><mn>2</mn></math>) of both electron and muon. In this model, the electron <math><mi>g</mi><mo>−</mo><mn>2</mn></math> is deviated from the Standard Model (SM) prediction by the 1-loop diagrams involving the vectorlike leptons, while that of muon is deviated due to a nonvanishing gauge kinetic mixing with photons. We also argue that the <math><mi>W</mi></math>-boson mass can be deviated from the SM prediction due to the vectorlike lepton loops, so that the value obtained by the CDF II experiment can be explained. Thus, this model simultaneously explains the recent three anomalies in <math><mi>g</mi><mo>−</mo><mn>2</mn></math> of electron and muon as well as the <math><mi>W</mi></math>-boson mass. The constraints on the <math><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> dark photon can be avoided because of the semivisible decay of the dark photon, <math><msup><mi>A</mi><mo>′</mo></msup><mo>→</mo><mn>2</mn><mi>N</mi><mo>→</mo><mn>2</mn><mi>ν</mi><mn>2</mn><mi>χ</mi><mo>→</mo><mn>2</mn><mi>ν</mi><mn>4</mn><mi>e</mi></math>, where <math><mi>N</mi></math> is a SM singlet vectorlike neutrino and <math><mi>χ</mi></math> is a <math><mrow><mi>C</mi><mi>P</mi></mrow></math>-even Higgs boson of the <math><mi>U</mi><mo>(</mo><mn>1</mn><msup><mo>)</mo><mo>′</mo></msup></math> gauge symmetry.

Egypt

Waleed Abdallah

Mustafa Ashry

South Korea

Junichiro Kawamura

Ahmad Moursy

Semivisible dark photon in a model with vectorlike leptons for the <math><mo>(</mo><mi>g</mi><mo>−</mo><mn>2</mn><msub><mo>)</mo><mrow><mi>e</mi><mo>,</mo><mtext> </mtext><mi>μ</mi></mrow></msub></math> and <math><mi>W</mi></math>-boson mass anomalies

We investigate the inflationary cosmology involving an <math><mi>S</mi><mi>U</mi><mo>(</mo><mn>5</mn><mo>)</mo></math> GUT (grand unified theory) singlet scalar with nonminimal coupling to the Ricci scalar. In this scenario the scale of grand unification is set by the inflaton vacuum expectation value when the inflaton rolls down its potential towards its minimum <math><mi>v</mi></math>, thereby relating inflationary dynamics to GUT symmetry breaking with a prediction of <math><mi>r</mi><mo>≃</mo><mn>0.025</mn></math> for the tensor-to-scalar ratio to be tested by the next generation of CMB experiments. We show in this inflationary framework involving an inflection point how a suitable choice of parameters in <math><mi>S</mi><mi>U</mi><mo>(</mo><mn>5</mn><mo>)</mo></math> leads to a bump in the scalar power spectrum with the production of primordial blackholes (PBH) of masses <math><msup><mn>10</mn><mn>17</mn></msup><mi>–</mi><msup><mn>10</mn><mn>18</mn></msup><mtext> </mtext><mtext> </mtext><mi>g</mi></math> (<math><msup><mn>10</mn><mrow><mo>−</mo><mn>16</mn></mrow></msup><mi>–</mi><msup><mn>10</mn><mrow><mo>−</mo><mn>15</mn></mrow></msup><msub><mi>M</mi><mo>⊙</mo></msub></math>). We derive the constraints on the self-quartic and mixed-quartic couplings of the inflaton in <math><mi>S</mi><mi>U</mi><mo>(</mo><mn>5</mn><mo>)</mo></math> that are consistent with the inflationary analysis. Moreover, we also show that this scenario leads to large amplitude induced second-order tensor perturbations propagating as gravitational waves (GWs) with an amplitude <math><msub><mi>Ω</mi><mi>GW</mi></msub><msup><mi>h</mi><mn>2</mn></msup><mo>∼</mo><mn>5</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>10</mn></mrow></msup><mi>–</mi><msup><mn>10</mn><mrow><mo>−</mo><mn>8</mn></mrow></msup></math> and peak frequency <math><mrow><msub><mrow><mi>f</mi></mrow><mrow><mi>peak</mi></mrow></msub><mo>∼</mo><mo>(</mo><mn>0.1</mn><mi>–</mi><mn>300</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>Hz</mi></mrow></math>, which can be detected in the next-generation GW observatories like LISA, BBO, ET, etc. Thus, we unify the <math><mi>S</mi><mi>U</mi><mo>(</mo><mn>5</mn><mo>)</mo></math> framework with PBH via inflection-point inflation showing how the upcoming measurements of PBH and GW will enable us to probe the scale of <math><mi>S</mi><mi>U</mi><mo>(</mo><mn>5</mn><mo>)</mo></math> symmetry breaking, and thereby complementing the laboratory-based experiments. We also discuss scenarios involving the Pati-Salam and trinification gauge groups and its impact on quartic and mixed-quartic couplings that may lead to PBH and detectable GW signals.

Poland

Anish Ghoshal

United States

Qaisar Shafi

Cosmological probes of grand unification: Primordial black holes and scalar-induced gravitational waves

We propose a modification to the standard hybrid inflation model [A. D. Linde, Hybrid inflation, Phys. Rev. D 49, 748 (1994).], that connects a successful hybrid inflation scenario to the standard model Higgs sector, via the electroweak vacuum stability. The proposed model results in an effective inflation potential of a hilltop type, with both the trans-Planckian and sub-Planckian inflation regimes consistent with the recent Planck/BICEP combined results. Reheating via the inflation sector decays to right-handed neutrinos is considered. An upper bound on the reheating temperature <math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>R</mi></mrow></msub><mo>≲</mo><mn>2</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>11</mn></mrow></msup><mo>(</mo><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>13</mn></mrow></msup><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, for large (small) field inflation, will suppress contributions from one-loop quantum corrections to the inflation potential. This may push the neutrino Yukawa couplings to be <math><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></math> and affect the vacuum stability. We show that the couplings of the SM Higgs field to the inflation sector can guarantee the electroweak vacuum stability up to the Planck scale. The so-called hybrid Higgs-inflaton model leads to a positive correction for the Higgs quartic coupling at a threshold scale, which is shown to have a very significant effect in stabilizing the electroweak vacuum. We find that even with <math><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></math> neutrino Yukawa couplings, threshold corrections leave the SM vacuum stability intact.

Merna Ibrahim

Esraa Elkhateeb

Adel M. Awad

Modified hybrid inflation, reheating, and stabilization of the electroweak vacuum

We develop a model of sneutrino inflation that is charged under U(1) B−L  gauge symmetry, in no-scale supergravity framework. The model provides an interesting modification of tribrid inflation. We impose U(1) R  symmetry on the renormalizable level while allow Planck suppressed non-renormalizable operators that break R-symmetry. This plays a crucial role in realizing a Starobinsly-like inflation scenario from one hand. On the other hand it plays an essential role, as well as SUSY breaking effects, in deriving the tiny neutrino masses via TeV inverse seesaw mechanism. Thus, we provide an interpretation for the extremely small value of the μ  S  mass parameter required for inverse seesaw mechanism. We discuss a reheating scenario and possible constraints on the model parameter space in connection to neutrino masses.

No-scale gauge non-singlet inflation inducing TeV scale inverse seesaw mechanism

In this paper we provide a no-scale supergravity scenario of hybrid inflation with R-symmetry being broken maximally. We investigate the inflation dynamics in details in both cases of pure F-term hybrid inflation and when adding constant Fayet-Iliopoulos D-terms. The effective inflation potential is asymptotically flat in a region of the parameter space in both cases. We explore all regions in the parameter space when discussing the constraints from the observables. We point out a connection between inflation, R-symmetry breaking and GUT scales. The moduli backreaction and SUSY breaking effects are investigated in a specific stabilization mechanism. We emphasis that a successful reheating is not affected by R-symmetry breaking, but it has interesting consequences. We study the reheating in flipped GUT model. We argue in favor of Z 2 symmetry associated with flipped GUT models to avoid phenomenologically dangerous operators and allow for decay channels for the inflaton to right-handed neutrinos (sneutrinos).

No-scale hybrid inflation with R-symmetry breaking

We consider a cosmological inflation scenario based on a no-scale supergravity sector with <math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mi>R</mi></msub></math> symmetry. It is shown that a tree level <math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mi>R</mi></msub></math> symmetric superpotential alone does not lead to a slowly rolling scalar potential. A deformation of this tree level superpotential by including an explicit <math><mi>R</mi></math> symmetry breaking term beyond the renormalizable level is proposed. The resulting potential is found to be similar (but not exactly the same) to the one in the Starobinsky inflation model. We emphasize that for successful inflation, with the scalar spectral index <math><msub><mi>n</mi><mi>s</mi></msub><mo>∼</mo><mn>0.96</mn></math> and the tensor-to-scalar ratio <math><mi>r</mi><mo>&lt;</mo><mn>0.08</mn></math>, a correlation between the mass parameters in the superpotential and the vacuum expectation value of the modulus field <math><mi>T</mi></math> in the Kähler potential must be adopted.

Shaaban Khalil

India

Abhijit Kumar Saha

Arunansu Sil

<math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mi>R</mi></msub></math> inspired inflation model in no-scale supergravity

In this paper, we embed the model of flipped GUT sneutrino inflation — in a flipped SU(5) or SO(10) set up — developed by Ellis et al. in a supergravity framework. The GUT symmetry is broken by a waterfall which could happen at early or late stage of the inflationary period. The full field dynamics is thus studied in detail and these two main inflationary configurations are exposed, whose cosmological predictions are both in agreement with recent astrophysical measurements. The model has an interesting feature where the inflaton has natural decay channels to the MSSM particles allowed by the GUT gauge symmetry. Hence it can account for the reheating after the inflationary epoch.

Norway

Tomás Gonzalo

Belgium

Lucien Heurtier

Sneutrino driven GUT inflation in supergravity

We review moduli stabilization in type IIB string theory compactification with fluxes. We focus on KKLT and Large Volume Scenario (LVS). We show that the predicted soft SUSY breaking terms in KKLT model are not phenomenological viable. In LVS, the following result for scalar mass, gaugino mass, and trilinear term is obtained: <math id="M1"><msub><mrow><mi>m</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><msub><mrow><mi>m</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>=</mo><mo>-</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><msub><mrow><mi>m</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math>, which may account for Higgs mass limit if <math id="M2"><msub><mrow><mi>m</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>~</mo><mi>O</mi><mo>(</mo><mn>1.5</mn><mo>)</mo></math> TeV. However, in this case, the relic abundance of the lightest neutralino cannot be consistent with the measured limits. We also study the cosmological consequences of moduli stabilization in both models. In particular, the associated inflation models such as racetrack inflation and Kähler inflation are analyzed. Finally, the problem of moduli destabilization and the effect of string moduli backreaction on the inflation models are discussed.