arXiv subjects

Rin Takada

Publications and source records attributed to Rin Takada.

7 recordsLinked to original sources

arXiv2026

Imaginary Rotation Breaks Charge Conjugation in Hot QCD

Starting from the identity $e^{2\pi i J_z}=(-1)^{F}=e^{i\pi Q}$ on the color-singlet physical state space, we derive a density-operator identity that ties imaginary rotation to an imaginary quark chemical potential, $\rho(\Omega_I+2\pi,\theta_q)=\rho(\Omega_I,\theta_q+\pi)$. Hence imaginarily rotating $SU(3)$ QCD at $(\Omega_I,\theta_q)=(2\pi,0)$ is mapped exactly onto the Roberge-Weiss (RW) point $(0,\pi)$, where charge conjugation $C$ is spontaneously broken above the RW endpoint---a conclusion independent of any model or approximation. Minimizing the one-loop effective potential on the rotation axis, we obtain analytically, for three massless flavors, the second-order transition at $\Omega_{I,C}/\pi=(22-2\sqrt{22})/9$, and a subsequent first-order transition at $\Omega_{I,{\rm lock}}/\pi=2/3+2\sqrt{111}/27$. At smaller $\Omega_I$, a continuous degeneracy of the massless one-loop approximation leaves the realization of $C$ undecided; a finite strange-quark mass lifts it. We also state how the exact relations and the on-axis predictions can be tested in lattice QCD.

hep-ph↗

arXiv2026

Long-wavelength amplification of an NLS conserved-charge violation in a one-dimensional Gross-Pitaevskii-Poisson field

Can weak self-gravity be treated as a small, generic perturbation of the integrable one-dimensional cubic nonlinear Schr\"odinger equation? We test this question by following the first nontrivial local NLS charge, $Q_3$. In the Gross-Pitaevskii-Poisson model it obeys the exact identity $\dot Q_3=\kappa F_3$, where $F_3$ is the instantaneous gravitational force on the charge. We quantify the initial violation through the normalized mean-square displacement of $Q_3$. Its curvature coefficient, $A_3={\rm Var}(F_3)/{\rm Var}(Q_3)$, measures the root-mean-square initial speed of the charge in units of the charge's own ensemble width. For a UV-regulated, linearly stable Gaussian initial-data preparation, Wick contraction gives ${\rm Var}(Q_3)=O(L)$ and ${\rm Var}(F_3)=O(L^2)$, hence $A_3=O(L)$. Direct Monte Carlo evaluation of the full nonlinear observables confirms these powers for $16\leq L\leq 512$. The linear growth of $A_3$ means that admitting longer wavelengths makes nominally weak gravity increasingly effective at displacing the NLS charge. Along the Jeans-stable sequence $\kappa_L\propto L^{-2}$, the associated short-time curvature scale is $L^{3/2}$ instead of the $L^2$ benchmark of an infrared-uniform perturbation. This is an equal-time result, not a relaxation-rate or KPZ measurement. The local sound sector contains the Burgers self-coupling required for KPZ, but unscreened gravity also generates a relevant inverse-gradient coupling and, at fixed strength, a Jeans band. A dynamical connection to KPZ therefore requires a projected charge-relaxation calculation and a branch-resolved structure-factor test.

cond-mat.stat-mech↗

arXiv2026

Resonant electromagnetic leptogenesis with coherent heavy-neutrino evolution

We study TeV-scale electromagnetic leptogenesis generated by the gauge-invariant neutrino-dipole operators $O_{NB}$ and $O_{NW}$. The benchmark Wilson coefficients are specified at the renormalization scale $\kappa_N=M_1=1\,\mathrm{TeV}$ and related to their values at $\kappa_{\rm match}=3\,\mathrm{TeV}$ through the coupled one-loop $\nu$SMEFT evolution. The collision network contains the symmetric-phase $1\leftrightarrow3$ and crossed $2\leftrightarrow2$ processes generated by the linear field-strength vertices and the VEV-induced two-body $\gamma$, $Z$, and $W$ channels through the electroweak crossover. We use a factorized leading-moment, momentum-averaged Markovian treatment for two $2\times2$ heavy-flavor density matrices, one for each helicity. Pole-resummed two-state effective couplings enter the lepton and antilepton collision tensors, while the off-diagonal density matrices describe coherent evolution and collision damping. Three resolved flavor charges are coupled to a finite-rate sphaleron equation, yielding the frozen baryon yield $Y_B^{\rm FO}$. For the benchmark $\tilde m^{\rm EM}_1=3.97\times10^{-2}\,\mathrm{eV}$, the decay-only pole prescription, in which only decay contributions enter the absorptive pole matrix, gives the locally optimized positive near-resonant maximum $Y_B^{\rm FO}=+5.50\times10^{-5}$ at $\Delta M=1.29\times10^{-11}\,\mathrm{GeV}$. Adding the thermally averaged crossed-scattering moment to the pole matrix defines the decay-plus-scattering prescription and shifts the maximum to $Y_B^{\rm FO}=+8.44\times10^{-5}$ at $\Delta M=1.83\times10^{-11}\,\mathrm{GeV}$. The corresponding signed mass-splitting curves cross the observed value $Y_B^{\rm obs}$ at $\Delta M=1.68\times10^{-5}\,\mathrm{GeV}$ and $2.34\times10^{-5}\,\mathrm{GeV}$.

hep-ph↗

arXiv2025

Yukawa-assisted charged-lepton dipoles in resonant electromagnetic leptogenesis

We study the charged-lepton dipole contribution that is linear in the neutrino-dipole coefficients $C_{NB,NW}$ and in the renormalizable neutrino Yukawa matrix $Y_\nu$. We consider a resonant EMLG benchmark with dipole-sector coefficients renormalized at $\kappa_N=M_1=1\,\mathrm{TeV}$ and evolved through the coupled one-loop RGE to $\kappa_{\rm match}=3\,\mathrm{TeV}$, a factorized flavor structure, and $\tilde{m}^{\rm EM}_1=3.97\times 10^{-2}\,\mathrm{eV}$. Since these inputs do not determine $Y_\nu$, we impose the conditional width bound $\Gamma_Y^{(0)}\leqslant\epsilon\Gamma_{\rm EM}^{(0)}$ and a vanishing direct ultraviolet charged-lepton dipole, derive the one-loop $\nu$SMEFT leading logarithm, and apply the tree-level electroweak projection and one-loop QED evolution in LEFT. For $\epsilon=10^{-2}$ and two coherently aligned heavy states, the width-only envelopes are $\mathrm{BR}(\mu\to e\gamma)\leqslant2.77\times10^{-28}$, $|d_e|\leqslant5.71\times10^{-37}\,e\,\mathrm{cm}$, and $|\Delta a_\mu|\leqslant1.31\times10^{-21}$. The factorized flavor structure and $C_{NW}/C_{NB}=1.739$ give smaller conditional bounds. The benchmark phase $\phi_{BW}=0$, for which $\rho_{BW}=+1.739$, lies near the charged-lepton photon-dipole blind direction. The vacuum local coefficient contains no resonant pole denominator. The two thermal pole prescriptions enter the low-energy comparison only through the mass splittings selected by the transport calculation, producing a relative change of order $\Delta M/M_1$.

hep-ph↗

arXiv2025

Electromagnetic Leptogenesis -- an EFT-Consistent Analysis via Wilson Coefficients. Part II. Low-Scale, Resonant Regime

We study electromagnetic leptogenesis (EMLG) in the low-scale, resonant regime within a fully effective-field-theory (EFT)--consistent framework. Starting from a UV Lagrangian and performing a one-loop matching to obtain the gauge-invariant dipole operator $O_{NB}$ with its Wilson coefficient $C_{NB}$, we implement the Pilaftsis--Underwood resummation for the self-energy contributions to the CP asymmetries and evolve a flavour covariant transport system across the electroweak window. In the quasi-degenerate limit $M_m-M_i\simeq\varGamma_m/2$, the CP-odd source acquires a Breit--Wigner--form enhancement whereas the washout saturates, with the freeze-out baryon asymmetry achieving $Y_B^{\rm FO}\gtrsim 10^{-10}$ across the strong-washout regime, comfortably above the observed value $Y_B^{\rm obs}\simeq 8.7\times 10^{-11}$. This establishes resonant EMLG at $O(100)~{\rm GeV}$ as a viable EFT-based mechanism for the baryon asymmetry of the Universe.

hep-ph↗

arXiv2025

Electromagnetic Leptogenesis -- an EFT-Consistent Analysis via Wilson Coefficients. Part I. Low-Scale, Non-Resonant Regime

We analyse electromagnetic leptogenesis within the framework of an effective field theory, where the dynamics is governed by the gauge-invariant dipole operator $O_{NB}$. The Wilson coefficient $C_{NB}$ is matched at one loop and renormalisation-group (RG) evolved to the electroweak scale. After electroweak symmetry breaking we compute flavour-dependent two-body decay widths and CP asymmetries for $N\to\nu+\gamma/Z$, and solve the fully flavoured Boltzmann equations. In the $N_1$-dominated regime the freeze-out baryon asymmetry is $Y_B^{\rm FO}\lesssim 10^{-17}$, far below the observed value $Y_B^{\rm obs}\simeq 8.7\times 10^{-11}$. The suppression is structural: gauge invariance forces a Higgs insertion; therefore dipole couplings $\mu\propto v/M_{\Psi}^2$ while the matched coefficient $C_{NB}$ is loop-generated and further reduced by RG running. We note that in the quasi-degenerate limit the self-energy resonance can be operative and suggest a plausible path to $Y_B^{\rm obs}$.

hep-ph↗

arXiv2025

Leptogenesis in the presence of density perturbations

We point out a new effect on the freeze-out process of heavy particles induced by density perturbations in the early universe, which we call ``acoustically driven freeze-out.'' This beyond-linear effect is caused by the exponential decoupling of heavy particles from the thermal bath in the presence of density perturbations, and already at moderately large values $\delta T / \bar{T} = O (10^{-2})$ it cannot be captured by linear perturbation theory. We illustrate this effect with leptogenesis taking the decay and inverse decay of heavy neutrinos into account, and discuss its phenomenological implications. We found that perturbations always enhance the (spatially averaged) values of the final lepton asymmetry, and as a result, constraints on the mass of heavy neutrinos are found to be relaxed in the presence of perturbations.

hep-ph↗