arXiv subjects

Yakov Mandel

Publications and source records attributed to Yakov Mandel.

3 recordsLinked to original sources

arXiv2026

Sign-Locked Gravitational Baryogenesis from Bulk Viscosity and Cosmological Particle Creation

We study a concrete realization of gravitational baryogenesis in which a small bulk-viscous deformation of an otherwise radiation-dominated early universe generates a sign-definite curvature source. The key point is thermodynamic irreversibility: positive entropy production makes the driving term monotonic and therefore avoids the freeze-out cancellation that suppresses rapidly oscillating or sign-changing sources. Motivated by a simple first-order transfer-function diagnostic, we analyze the standard curvature-current operator $\mathcal{L}_{\rm int}=(c/M^2)\,\partial_\mu R\,J^\mu_{B-L}$ in a near-radiation background with effective pressure $p_{\rm eff}=p-3\zeta H$ and $\zeta=\xi \rho/H$. For $\xi>0$ one finds $R\neq 0$, $\dot R>0$, and a baryon asymmetry $\eta \propto \xi T_D^5/(M^2 \bar M_{\rm Pl}^3)$. We derive the viable $(T_D,M,\xi)$ region, include entropy dilution from a finite viscous epoch, and show that the observed $\eta_{\rm obs}\simeq 8.6\times10^{-11}$ can be reproduced in a parameter region consistent with current cosmological bounds while maintaining EFT control. The highest-scale benchmarks should be read conditionally on a very high reheating scale in view of current tensor limits. A particle-creation sector of heavy GUT-scale fields then provides a phenomenological motivation for the required range $\xi\sim10^{-4}$--$10^{-3}$. We also discuss the known higher-derivative instability of gravitational baryogenesis and the role of stabilized or completed embeddings.

hep-ph↗

arXiv2026

Gravitational Baryogenesis from Entropy Production and Parity Violation: A Unified Framework

We present a unified framework for gravitational baryogenesis combining two mechanisms: (i) an entropy-clock source that generates a sign-definite baryon chemical potential mu_B proportional to d ln S/dt during irreversible entropy production, and (ii) CP violation from a gravitational theta term theta R Rtilde analogous to the QCD vacuum angle. The entropy-clock evades adiabatic cancellation that suppresses purely oscillatory chemical potentials under smooth freeze-out; we quantify this with a universal low-pass transfer function F(x)=1/sqrt(1+x^2), where x=omega*tau_off. A minimal UV completion via a dilaton coupled to the conformal anomaly yields the entropy-clock coupling with decay constant f_sigma ~ 10^17-10^18 GeV. The theta term provides CP violation through interference between topologically distinct gravitational configurations; we estimate an instanton suppression factor kappa_inst ~ 10^-2-10^-1. The combined mechanism predicts Y_B ~ c*kappa*Pi_eff*epsilon_eff, linking the baryon asymmetry to the reheating temperature, the theta angle, and the entropy-production history. For Loop Quantum Cosmology bounces we derive an analytic expression for the circular polarization of the stochastic gravitational-wave background, with |Pi| ~ pi*|theta| for horizon-crossing modes, potentially testable by future space-based detectors.

hep-ph↗

arXiv2026

Baryogenesis from the Thermodynamic Arrow of Time: a Transfer-Function Bound and an Entropy-Clock Mechanism

We formulate a transfer test for baryogenesis driven by time-dependent derivative sources. A zero-mean oscillatory chemical potential convolved with a smooth finite-time kernel is low-pass filtered. For a one-sided exponential effective kernel, the signed response is $I_\varphi(x)=(\cos\varphi-x\sin\varphi)/(1+x^2)$ and the phase-optimized envelope is $F_{\rm amp}(x)=1/\sqrt{1+x^2}$, with $x=\omega\tau_{\rm off}$. Its sharp onset gives a $1/x$ high-frequency tail; smoother turn-ons can suppress more strongly. An integration-by-parts bound shows that rapidly sign-changing sources are controlled by their residual low-frequency component. We then study an entropy-clock ansatz, $\theta_X=\epsilon_X\ln(S/S_0)$, giving $\mu_X=\epsilon_X d\ln S/dt$ during entropy-producing reheating; the yield equation includes entropy dilution. During perturbative matter-dominated reheating, $S\propto a^{15/8}$ and $\Pi=d\ln S/d\ln a=15/8$ before completion. Successful freeze-out requires overlap between entropy production and charge violation. In a Weinberg-operator $B-L$ benchmark this selects $T_R={\cal O}(T_F)$, with $T_F\sim10^{12}$--$10^{13}\,\mathrm{GeV}(0.05\,\mathrm{eV}/\bar m_\nu)^2$. If $T_R\gg T_F$, the source ends before freeze-out and is washed out; if $T_R\ll T_F$, the interaction is never efficient during reheating. For a direct baryon source, $|\epsilon_X\Pi_{\rm eff}|\simeq3.2\times10^{-3}(10^{12}\,\mathrm{GeV}/T_{\rm ov})$; sphaleron reprocessing of a $B-L$ source increases this by $79/28$. With $\Pi=15/8$, this gives $|\epsilon_X|\zeta\simeq1.7\times10^{-3}$ and $4.8\times10^{-3}$, respectively, at $T_{\rm ov}=10^{12}\,\mathrm{GeV}$. The entropy-clock source is phenomenological; a UV completion must explain why the charge-biasing variable tracks $\ln S$ or an equivalent monotonic dissipative variable.

hep-ph↗