Large primordial lepton flavor asymmetries with almost vanishing total baryon-minus-lepton number can evade the usual BBN and CMB constraints if neutrino oscillations lead to perfect flavor equilibration. Solving the momentum averaged quantum kinetic equations (QKEs) describing neutrino oscillations and interactions, we perform the first systematic investigation of this scenario, uncovering a rich flavor structure in stark contradiction to the assumption of simple flavor equilibration. We find (i) a particular direction in flavor space, ∆$\textit{n}$ ≃ – 2/3 (– 1)∆$\textit{n}$ for normal (inverted) neutrino mass hierarchy, in which the flavor equilibration is efficient and primordial asymmetries are essentially unconstrained, (ii) a minimal washout factor, $$ {\left.\Delta {n}_e^2\right|}_{\textrm{BBN}} $$ $\textit{≤}$ 0.03 (0.016) ∑ $$ {\left.\Delta {n}_{\alpha}^2\right|}_{\textrm{ini}} $$ yielding a conservative estimate for the allowed primordial asymmetries in a generic flavor direction, and (iii) particularly strong or weak washout if one of the initial flavor asymmetries vanishes due to non-adiabatic muon- or electron-driven MSW transitions. These results open up the possibility of a first-order QCD phase transition facilitated by large lepton asymmetries as well as baryogenesis from large and compensated ∆$\textit{n}$ = ∆$\textit{n}$ asymmetries. Our systematic approach of deriving momentum averaged QKEs includes collision terms beyond the damping approximation, energy transfer between the neutrino and electron-photon plasma, and provides a fast and reliable way to investigate the impact of primordial lepton asymmetries at the time of BBN. We publicly release the Mathematica code COFLASY-M on https://github.com/mariofnavarro/COFLASY which solves the QKEs numerically.

Switzerland

Valerie Domcke

Miguel Escudero

United Kingdom

Mario Navarro

United States

Stefan Sandner

Lepton flavor asymmetries: from the early Universe to BBN

We present a new exact solution of Einstein-Maxwell field equations which represents a rotating black hole with both electric and magnetic charges immersed in a universe which itself is also rotating and magnetized, i.e. the dyonic Kerr-Newman black hole in a Melvin-swirling universe.

Italy

Andrea Pinto

Silke Klemm

Adriano Viganò

Kerr-Newman black hole in a Melvin-swirling universe

Gravitational waves (GWs) from compact binary coalescence (CBC) can directly determine the luminosity distance but usually can not obtain information about the redshift. This assumes that the GW source is at the flat background. However, if the GWs are generated in a not flat but accelerating universe, the GWs should carry the information of the curvature spacetime. The expansion of the Universe is accelerating can be interpreted as the existence of the cosmological constant Λ. In this study, we investigate the behavior of gravitational waves in the presence of a cosmological constant in the early universe. We rigorously analyze the merger rate of binary primordial black holes (PBHs) and the corresponding signal-to-noise ratio within the framework of space-borne interferometers (like Laser Interferometer Space Antenn, TAIJI and Tian-Qin). We find that binary PBHs with a total mass of $\textit{M}$ = 1000$\textit{M}$ and a redshift larger than $\textit{z}$ = 500 are the ideal system for studying the effect of the cosmological constant through LISA. By computing the Fisher information matrix, we establish that the cosmological constant can be effectively constrained.

China

Song Li

Wen-Biao Han

Inferring the cosmological constant in early Universe only by gravitational waves

The electric dipole moment is examined in a three-loop neutrino mass model with dark matter originally proposed in Aoki et al. [$\textit{Phys. Rev. Lett.}$ (2009) 051805]. The model contains a $\textit{CP}$-violating phase in the Higgs potential which plays an important role in electroweak baryogenesis and is thus expected to explain the baryon asymmetry of the Universe simultaneously. However, such a $\textit{CP}$-violating phase is severely constrained by the measurements of the electron electric dipole moment (eEDM), and a suppression mechanism for the eEDM is necessary to explain the observed baryon asymmetry while avoiding the constraint. In this paper, we examine neutrino mass, lepton-flavor-violating processes, dark matter, and the eEDM in the model. We show that the eEDM can be suppressed by destructive interference between the $\textit{CP}$-violating phases in the Higgs sector and the dark sector with large $\textit{CP}$-violating phases. We propose some benchmark scenarios including $\textit{O}$(1) $\textit{CP}$-violating phases where tiny neutrino mass and dark matter can be explained while avoiding all current experimental and theoretical constraints. These $\textit{CP}$-violating phases are expected to be large enough to generate the observed baryon asymmetry in the electroweak baryogenesis scenario.

South Korea

Kazuki Enomoto

Japan

Shinya Kanemura

Sora Taniguchi

The electric dipole moment in a model for neutrino mass, dark matter and baryon asymmetry of the Universe

Using high-performance computing, we obtain the wave function of a quantum cosmology model which aims at describing the early moments of the Universe. The model has a Friedmann-Robertson-Walker geometry with positive curvature of the spatial section, and its matter content consists of a massive scalar field conformally coupled to gravity, a radiation perfect fluid and a positive cosmological constant. The Wheeler-DeWitt equation of that model may be written in a form of a bi-dimensional Schrödinger equation with the presence of a potential barrier. After numerically solving this equation we let the wave function evolve until it reaches the potential barrier, either tunneling through or circumventing it. Using the many-worlds interpretation of quantum mechanics, we compute the expectation values of both the scale factor and the scalar field. If we consider that the present Universe was born after tunneling/circumventing the potential barrier, these results may provide a new perspective on the birth of the Universe and the fundamental processes that shaped its early evolution.

Brazil

G.A. Monerat

H.J. Brumatto

G. Oliveira-Neto

F.G. Alvarenga

E.V. Corrêa Silva

A.L.B. Ribeiro

Non-singular birth of the universe: High-performance numerical solutions of the Wheeler-DeWitt equation

We search for the leptonic decay $ D^+\to e^+\nu_{e} $ using an $ e^+e^- $ collision data sample with an integrated luminosity of 20.3 fb $ ^{-1} $ collected with the BESIII detector at a center-of-mass energy of 3.773 GeV. Significant signal is not observed, and an upper limit on the branching fraction of $ D^+\to e^+\nu_{e} $ is set as $ 9.7 \times 10^{-7} $ , at a confidence level of 90%. Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

A. Amoroso

Q. An

Y. Bai

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

R.A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

Z.Y. Chen

S.K. Choi

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

Y.T. Feng

M. Fritsch

C.D. Fu

J.L. Fu

Y.W. Fu

H. Gao

Search for the leptonic decay ${\boldsymbol D^{\bf +}{\bf\to}{\boldsymbol e}^{\bf +}\boldsymbol\nu_{\boldsymbol e}}$ * Supported in part by the National Key R&D Program of China (2023YFA1606000, 2020YFA0406400, 2020YFA0406300), the National Natural Science Foundation of China(NSFC) (11635010, 11735014, 11935015, 11935016, 11875054, 11935018, 12025502, 12035009, 12035013, 12061131003, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265, 12221005, 12225509, 12235017, 12361141819), the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program, the CAS Center for Excellence in Particle Physics (CCEPP), the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U2032104, U1832207), the 100 Talents Program of CAS, the Excellent Youth Foundation of Henan Scientific Commitee (242300421044), the Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology, the German Research Foundation DFG (FOR5327), the Istituto Nazionale di Fisica Nucleare, Italy, the Knut and Alice Wallenberg Foundation (2021.0174, 2021.0299), the Ministry of Development of Turkey (DPT2006K-120470), the National Research Foundation of Korea (NRF-2022R1A2C1092335), the National Science and Technology Fund of Mongolia, the National Science Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources & Institutional Development, Research, and Innovation of Thailand (B16F640076, B50G670107), the Polish National Science Center (2019/35/O/ST2/02907), the Swedish Research Council (2019.04595), the Swedish Foundation for International Cooperation in Research and Higher Education (CH2018-7756), and the US Department of Energy (DE-FG02-05ER41374).

Affleck-Dine baryogenesis generated high baryon density in the early Universe. The baryon chemical potential enhanced the potential barrier and significantly reduced the decay rate of false vacuum, which decreased from infinity at the critical end point to zero at the critical nucleation point. When the decay rate reached zero, the false vacuum of high baryon density quark matter was unlikely to decay and could persist over cosmological time scales. Therefore, primordial quark nuggets (PQNs) could form and survive in the early Universe as the seeds of compact stars. This new mechanism for the formation of PQNs is different from Witten's stable droplet of quark matter.

Jingdong Shao

Hong Mao

Mei Huang

Nanohertz gravitational waves and primordial quark nuggets from dense QCD matter in the early Universe * Supported in part by the National Natural Science Foundation of China (12235016, 12221005), and the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34030000)

We analyze the correlation function in Jackiw–Teitelboim gravity using three approaches: by summing over all geodesics connecting boundary operators, integrating over the region of moduli space determined by the “no-shortcut condition,” and using the formula for the universal spectral density correlation in the <inline-formula><tex-math id='TM0001' notation='LaTeX'>$\tau$</tex-math></inline-formula>-scaling limit. We find that the behaviors of the three results coincide at late times: they all exhibit a &#8220;ramp&#8221; instead of permanent decay. Using the third approach we also confirm that the &#8220;plateau&#8221; appears after <inline-formula><tex-math id='TM0002' notation='LaTeX'>$T_H=2\pi e^{S_0}\widehat{\rho }_0(E)$</tex-math></inline-formula>. Overall, our results are consistent with the spectral form factor analysis. We also calculate the Einstein&#8211;Rosen bridge length <inline-formula><tex-math id='TM0003' notation='LaTeX'>$\langle \ell (T) \rangle$</tex-math></inline-formula> using the three approaches and find that the results are in good agreement with each other. We also find that the <inline-formula><tex-math id='TM0004' notation='LaTeX'>$\langle \ell (T) \rangle$</tex-math></inline-formula> grows as a cubic function in <inline-formula><tex-math id='TM0005' notation='LaTeX'>$T$</tex-math></inline-formula> due to the contribution from geometry including one observable baby universe, and converges to a constant after <inline-formula><tex-math id='TM0006' notation='LaTeX'>$T=T_H$</tex-math></inline-formula>. For the geometry with one baby universe, we compute the size <inline-formula><tex-math id='TM0007' notation='LaTeX'>$\langle b(T) \rangle$</tex-math></inline-formula> of the baby universe and find that it is of the same order as <inline-formula><tex-math id='TM0008' notation='LaTeX'>$\langle \ell (T) \rangle$</tex-math></inline-formula>. This result is consistent with the baby universe emission mechanism previously claimed.

Masayoshi Sato

What Happens Due to the Baby Universe Effect in Jackiw–Teitelboim Gravity? Analysis of Correlation Functions and Einstein–Rosen Bridge Length at Late Time Using Three Approaches

In this paper, we will study the phenomenon of neutrino oscillations when traveling through the gravitational field of a black hole embedded in a spatially homogeneous and isotropic flat universe. Thus, we will compute the phase shift for neutrinos within the McVittie spacetime building upon the description of their geodesic motion. Standard assumptions of ultrarelativistic neutrinos with degeneracy between their energy eigenstates are maintained, while no screening mechanisms are needed; the correctness of our result can therefore be checked against relevant literature limiting scenarios of static isolated Schwarzschild black hole and of the Friedmann universe backgrounds, separately. We will compare and contrast the effects of local galactic and global cosmic physics, accounted for by the black hole mass and the Hubble rate, in the phase shift; its numerical value will be estimated for some realistic scenarios by re-casting it in terms of measurable astrophysical and cosmological parameters. We will identify the range of applicability of our model as for neutrinos sourced in the accelerated expansion phase of the universe, with the roles of the cosmological constant, dark matter and black hole mass scrutinized in the loss of coherence of the wavepackets. Our analysis will allow us to identify similarities and differences in the interaction between neutrinos and <italic>matter</italic> or <italic>gravitational</italic> fields.

Daniele Gregoris

Neutrino oscillations in the background of a black hole embedded in an expanding Universe

In this paper we study the transition rates for the decay of <inline-formula><tex-math id='TM0003' notation='LaTeX'>$W^{\pm }$</tex-math></inline-formula> bosons into leptons in de Sitter spacetime. From the results obtained in the de Sitter geometry we recover the Minkowski limits of the transition rates. We also study the emission of <inline-formula><tex-math id='TM0004' notation='LaTeX'>$W^{\pm }$</tex-math></inline-formula> bosons by leptons, a process that is possible only in the large expansion conditions of the early universe. These results are obtainable due to perturbative methods that allow us to compute the transition amplitudes in the first order of perturbation theory. The resulting probabilities and rates depend on the particle masses and the Hubble parameter. In order to establish finite expressions for the probabilities and transition rates, we make use of dimensional regularization and the minimal subtraction method.

Romania

Amalia Dariana Fodor

Cosmin Crucean

Emission of <italic>W</italic> Bosons by Electrons and Decays of <italic>W</italic> Bosons in the Early Universe