Fri·Oct 28, 2022Friday·October 28, 2022

1. 01*

   Muon g-2 and a Geocentric New Field

   Hooman Davoudiasl🇺🇸 · Robert Szafron🇺🇸

   Light scalars can in principle couple to both bulk matter and fermion spin, with hierarchically disparate strengths. Storage ring measurements of fermion electromagnetic moments via spin precession can be sensitive to such a force, sourced by the Earth. We discuss how this force could lead to a deviation of the measured muon anomalous magnetic moment, $g-2$, from the Standard Model prediction. Due to its different parameters, the proposed JPARC muon $g-2$ experiment can provide a direct test of our hypothesis. A future search for the proton electric dipole moment can have good sensitivity for the coupling of the assumed scalar to nucleon spin. We also argue that supernova constraints on axion-muon coupling may not be applicable in our framework.

   hep-phhep-exPRL(2023)·13 citations
2. 02*

   Statistical Patterns of Theory Uncertainties

   Aishik Ghosh🇺🇸 · Benjamin Nachman🇺🇸 · Tilman Plehn🇩🇪 · Lily Shire🇺🇸 · Tim M.P. Tait🇺🇸 · Daniel Whiteson🇺🇸

   A comprehensive uncertainty estimation is vital for the precision program of the LHC. While experimental uncertainties are often described by stochastic processes and well-defined nuisance parameters, theoretical uncertainties lack such a description. We study uncertainty estimates for cross-section predictions based on scale variations across a large set of processes. We find patterns similar to a stochastic origin, with accurate uncertainties for processes mediated by the strong force, but a systematic underestimate for electroweak processes. We propose an improved scheme, based on the scale variation of reference processes, which reduces outliers in the mapping from leading order to next-to-leading-order in perturbation theory.

   hep-phSciPost Phys.Core(2023)·21 citations
3. 03*

   On Asymptotic Universality of Strong Interactions at Large Distances

   Vladimir A. Petrov🇷🇺

   We propose a generalisation of the Pomeranchuk theorem which argues that elastic cross-sections should show a universal energy dependence: difference of integrated elastic cross-sections of any pair of initial channels has to disappear at high enough energy

   hep-phPhys.Part.Nucl.Lett.(2023)·0 citations
4. 04*

   Estimates of exchange topological contributions and $CP$-violating observables in ${\Lambda }_b\to \Lambda \varphi$ decay

   Zhou Rui🇨🇳 · Jia-Ming Li🇨🇳 · Chao-Qi Zhang🇨🇳

   The penguin-dominated two-body weak decay of ${\Lambda }_b\to \Lambda \varphi$ is studied based on the perturbative QCD approach. In addition to the penguin emission diagrams, the penguin exchange and $W$ exchange ones are also accounted for. It is found that the penguin exchange contribution is in fact important and comparable to the penguin emission one, while the $W$ exchange contribution is highly Cabibbo-Kobayashi-Maskawa (CKM) suppressed. The predicted branching ratio, $\mathcal{B}({\Lambda }_b\to \Lambda \varphi )=6.9_{-2.0-1.6}^{+1.9+1.8}\times 10^{-6}$, is larger than the previous theoretical estimates but in comparison with the data from Particle Data Group at the level of 1 standard deviation. We also explore some pertinent decay asymmetry parameters that characterize the angular decay distributions. The inclusion of the $W$ exchange contribution provides the nonzero weak phase difference,consequently, allowing us to estimate the direct $CP$ violation and true triple product asymmetries in the concerned process. The numerical results demonstrate that the direct $CP$ violation is at the level of a few percent, and the true triple product asymmetries are also predicted to be tiny, of order $10^{-2}-10^{-4}$. The observed small $CP$-violating observables have shown no significant deviations from zero. Our predictions will be subject to stringent tests with precise data from LHCb in the future.

   hep-phhep-exPRD(2023)·15 citations
5. 05*

   Flow of charge and heat in thermal QCD within the weak magnetic field limit: A BGK model approach

   Anowar Shaikh🇮🇳 · Shubhalaxmi Rath🇮🇳 · Sadhana Dash🇮🇳 · Binata Panda🇮🇳

   We have computed the charge and heat transport coefficients of hot QCD matter by solving the relativistic Boltzmann transport equation using the BGK model approximation with a modified collision integral in the weak magnetic field regime. This modified collision integral enhances both charge and heat transport phenomena which can be understood by the large values of the above-mentioned coefficients in comparison to the relaxation collision integral. We have also presented a comparative study of coefficients like the electrical conductivity (${\sigma }_{el}$), Hall conductivity (${\sigma }_H$), thermal conductivity ($\kappa$) and Hall-type thermal conductivity(${\kappa }_H$) in weak and strong magnetic fields in the BGK model approximation. The effects of weak magnetic field and finite chemical potential on the transport coefficients have been explored using a quasiparticle model. Moreover, we have also studied the effects of weak magnetic field and finite chemical potential on Lorenz number, Knudsen number, specific heat, elliptic flow and Wiedemann-Franz law.

   hep-phhep-thnucl-thPRD(2023)·11 citations
6. 06*

   Cumulants from short-range correlations and baryon number conservation - next-to-leading order

   Michał Barej🇵🇱 · Adam Bzdak🇵🇱

   We calculate the baryon number cumulants within acceptance with short-range correlations and global baryon number conservation in terms of cumulants in the whole system without baryon conservation. We extract leading and next-to-leading order terms of the large baryon number limit approximation. Our results extend the findings of Refs. [1,2]. These approximations are checked to be very close to the exact results.

   hep-phhep-exnucl-exnucl-thPRC(2023)·5 citations
7. 07*

   Spin-dependent sub-GeV Inelastic Dark Matter-electron scattering and Migdal effect: (I). Velocity Independent Operator

   Jiwei Li🇨🇳 · Liangliang Su🇨🇳 · Lei Wu🇨🇳 · Bin Zhu🇨🇳

   The ionization signal provide an important avenue of detecting light dark matter. In this work, we consider the sub-GeV inelastic dark matter and use the non-relativistic effective field theory (NR-EFT) to derive the constraints on the spin-dependent DM-electron scattering and DM-nucleus Migdal scattering. Since the recoil electron spectrum of sub-GeV DM is sensitive to tails of galactic DM velocity distributions, we also compare the bounds on corresponding scattering cross sections in Tsallis, Empirical and standard halo models. With the XENON1T data, we find that the exclusion limits of the DM-proton/neutron and DM-electron scattering cross sections for exothermic inelastic DM are much stronger that those for the endothermic inelastic DM. Each limits of the endothermic inelastic DM can differ by an order of magnitude at most in three considered DM velocity distributions.

   hep-phJCAP(2023)·38 citations
8. 08*

   Thermodynamic properties of non-Hermitian Nambu--Jona-Lasinio models

   Alexander Felski🇩🇪 · Alireza Beygi🇩🇪 · S. P. Klevansky🇩🇪

   We investigate the impact of non-Hermiticity on the thermodynamic properties of interacting fermions by examining bilinear extensions to the $3+1$ dimensional $SU(2)$-symmetric Nambu--Jona-Lasinio (NJL) model of quantum chromodynamics at finite temperature and chemical potential. The system is modified through the anti-$PT$-symmetric pseudoscalar bilinear $\bar{\psi }{\gamma }_5\psi$ and the $PT$-symmetric pseudovector bilinear $i{B}_{\nu }\bar{\psi }{\gamma }_5{\gamma }^{\nu }\psi$, introduced with a coupling $g$. Beyond the possibility of dynamical fermion mass generation at finite temperature and chemical potential, our findings establish model-dependent changes in the position of the chiral phase transition and the critical end-point. These are tunable with respect to $g$ in the former case, and both $g$ and $|B|/B_0$ in the latter case, for both lightlike and spacelike fields. Moreover, the behavior of the quark number, entropy, pressure, and energy densities signal a potential fermion or antifermion excess compared to the standard NJL model, due to the pseudoscalar and pseudovector extension respectively. In both cases regions with negative interaction measure $I=ϵ-3p$ are found. Future indications of such behaviors in strongly interacting fermion systems, for example in the context of neutron star physics, may point toward the presence of non-Hermitian contributions. These trends provide a first indication of curious potential mechanisms for producing non-Hermitian baryon asymmetry. In addition, the formalism described in this study is expected to apply more generally to other Hamiltonians with four-fermion interactions and thus the effects of the non-Hermitian bilinears are likely to be generic.

   hep-phhep-thnucl-thPRD(2023)·4 citations
9. 09*

   Anatomy of ${\Lambda }_c^{+}$ semileptonic decays

   Chao-Qiang Geng🇨🇳 · Xiang-Nan Jin🇨🇳 · Chia-Wei Liu🇨🇳

   We present a systematic study of ${\Lambda }_c^{+}\to {\mathcal{B}}_q{\ell }^{+}{\nu }_{\ell }$ with ${\mathcal{B}}_q=(\Lambda ,n)$ and $\ell =(e,\mu )$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD (LQCD). With the HBM, we find that the branching fractions and polarization asymmetries of the daughter baryon $\Lambda$ are $\mathcal{B}({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e,\Lambda {\mu }^{+}{\nu }_{\mu },n{\ell }^{+}{\nu }_{\ell })=(3.78\pm 0.25,3.67\pm 0.23,0.40\pm 0.04)\%$ and ${\alpha }_{\Lambda }({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e,\Lambda {\mu }^{+}{\nu }_{\mu })=(-82.6,-82.3)\%$, respectively. From the LQCD, we obtain that ${\alpha }_{\Lambda }({\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e,{\mu }^{+}{\nu }_{\mu })=(-87.4\pm 1.0,-87.2\pm 1.0)\%$. We also explore the time-reversal asymmetries due to new physics beyond the standard model. All our results are consistent with the current experimental data, while some of them are accessible to the experiments at BESIII and Belle II.

   hep-phhep-exPRD(2023)·13 citations
10. 10*

    Schwinger particle production: Rapid switch off of the external field versus dynamical assistance

    I. A. Aleksandrov🇷🇺 · D. G. Sevostyanov🇷🇺 · V. M. Shabaev🇷🇺

    We consider the process of electron-positron pair production in the presence of strong electric backgrounds being rapidly switched on and off and examine the total particle yield. For sufficiently sharp field profiles, the particle number can be substantially enhanced. It is demonstrated that this enhancement is quite similar to the phenomenon of dynamical assistance by a weak high-frequency field superimposed on a strong background. Both these mechanisms are analyzed by means of exact numerical computations, worldline instanton approach, and the locally-constant field approximation. We identify the time scale of the switching profile leading to the pair-production enhancement and argue that the particle yield is highly unlikely to be increased by shaping the switch off of realistic laser pulses. On the other hand, we confirm that it is feasible to observe the dynamically assisted Schwinger effect by adding a rapidly oscillating field to a strong electric background.

    hep-phhep-thPRD(2025)·15 citations
11. 11*

    Lighting Electroweak-Violating ALP-Lepton Interactions at $e^{+}{e}^{-}$ and $ep$ Colliders

    Chih-Ting Lu🇨🇳

    Recently, Altmannshofer, Dror and Gori (2022) claimed there is a four-point interaction, $W$-$\ell$-$\nu$-$a$, in the electroweak-violating scenario of axion-like particle (ALP) and lepton interactions which plays a critical role in searching for ALPs from ${\pi }^{\pm }$, $K^{\pm }$ mesons and $W$ boson decays because of the novel energy enhancements. Inspired by this interesting finding, we first propose new t-channel processes, $e^{+}{e}^{-}\to {\nu }_{e}a\overline{{\nu }_e}$ and $e^{-}p\to {\nu }_{e}aj$, for electrophilic ALPs ($e$ALPs) which also involve $W$-$\ell$-$\nu$-$a$ four-point interaction and have obvious energy enhancement behaviors in their cross sections when the collision energy is increasing. On the other hand, heavier $e$ALPs mainly decay to a photon pair induced by the chiral anomaly instead of an electron-positron pair. Therefore, studies of these t-channel processes with a photon pair plus missing energy at $e^{+}{e}^{-}$ and $ep$ colliders open a new door to search for $e$ALPs at high energy colliders. The proposed search strategies are not only aiming to generate a larger production rate of ALPs, but also trying to distinguish electroweak-violating ALP-lepton interactions from electroweak-preserving ones.

    hep-phPRD(2023)·23 citations
12. 12*

    Freezing-in hadrophilic dark matter at low reheating temperatures

    Prudhvi N. Bhattiprolu🇺🇸 · Gilly Elor🇩🇪 · Robert McGehee🇺🇸 · Aaron Pierce🇺🇸

    If the reheating temperature at the end of inflation is low, of order 10 MeV, then dark matter produced through ultraviolet freeze-in has a large direct detection cross section. We study such a scenario in which dark matter is hadrophilic. This leads to dark matter-nucleon scattering cross sections of interest for near-future experiments for dark matter masses in the range of 100 keV-100 MeV. We explore how these predictions vary if reheating is non-instantaneous.

    hep-phJHEP(2023)·64 citations
13. 13*

    Dark photon and dark $Z$ mediated $B$ meson decays

    Alakabha Datta🇺🇸 · A. Hammad🇰🇷 · Danny Marfatia🇺🇸 · Lopamudra Mukherjee🇺🇸 · Ahmed Rashed🇺🇸

    We study flavor changing neutral current decays of $B$ and $K$ mesons in the dark $U(1{)}_D$ model, with the dark photon/dark $Z$ mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$, with $\ell =\mu ,e$, and $B_s\to \varphi {\mu }^{+}{\mu }^{-}$, the allowed parameter space is ruled out by measurements of atomic parity violation, $K^{+}\to {\mu }^{+}+invisible$ decay, and $B_s-{\overline{B}}_s$ mixing, among others. To evade constraints from low energy data, we extend the model to allow for (1) additional invisible $Z_D$ decay, (2) a direct vector coupling of $Z_D$ to muons, and (3) a direct coupling of $Z_D$ to both muons and electrons, with the electron coupling fine-tuned to cancel the $Z_D$ coupling to electrons via mixing. We find that only the latter case survives all constraints.

    hep-phhep-exJHEP(2023)·22 citations
14. 14*

    Weak-Scale Higgs Inflation

    Wen Yin🇯🇵

    The present measurement of the standard model (SM) parameters suggests that the Higgs effective potential has a maximum at the intermediate scale, and the electroweak (EW) vacuum is not absolutely stable. The simplest possibility for absolute EW stability may be introducing a very large Higgs-Ricci scalar non-minimal coupling. In this extension of the SM, I study the cosmic inflation driven by the Higgs field. Since the resulting Hubble parameter happens to be around the weak scale, I call this scenario $weak\text{-}scaleHiggsinflation$. It is pointed out that the cosmic-microwave background normalization of the scalar density perturbation can be enhanced compared with the conventional Higgs inflation prediction, thanks to the potential maximum predicted by the SM. It turns out in the Palatini formulation of the gravity with various higher dimensional terms suppressed by the scale close to the Planck scale that the inflation is successful, with a prediction of the running of the spectral index, ${\alpha }_s=-(3-4)\times 10^{-3}$, which can be tested in the future. I also argue the UV (in)sensitivity of the prediction, the fact that the parameter region for successful inflation is very close to the criticality for potential shapes for eternal and non-eternal inflation, and the phenomenological applications.

    hep-phgr-qcJCAP(2024)·15 citations
15. 15*

    Dynamics of Confined Monopoles and Similarities with Confined Quarks

    Gia Dvali🇩🇪 · Juan Valbuena-Bermudez🇩🇪 · Michael Zantedeschi🇩🇪

    In this work, we study the annihilation of a pair of `t Hooft-Polyakov monopoles due to confinement by a string. We analyze the regime in which the scales of monopoles and strings are comparable. We compute the spectrum of the emitted gravitational waves and find it to agree with the previously calculated point-like case for wavelengths longer than the system width and before the collision. However, we observe that in a head-on collision, monopoles are never re-created. Correspondingly, not even once the string oscillates. Instead, the system decays into waves of Higgs and gauge fields. We explain this phenomenon by the loss of coherence in the annihilation process. Due to this, the entropy suppression makes the recreation of a monopole pair highly improbable. We argue that in a similar regime, analogous behaviour is expected for the heavy quarks connected by a QCD string. There too, instead of re-stretching a long string after the first collapse, the system hadronizes and decays in a high multiplicity of mesons and glueballs. We discuss the implications of our results.

    ↳ hep-thgr-qchep-lathep-phPRD(2023)·16 citations
16. 16*

    Loading a relativistic kappa distribution in particle simulations

    Seiji Zenitani · Shin'ya Nakano

    A procedure for loading particle velocities from a relativistic kappa distribution in particle-in-cell (PIC) and Monte Carlo simulations is presented. It is based on the rejection method and the beta prime distribution. The rejection part extends earlier method for the Maxwell-Juttner distribution, and then the acceptance rate reaches ~95%. Utilizing the generalized beta prime distributions, we successfully reproduce the relativistic kappa distribution, including the power-law tail. The derivation of the procedure, mathematical preparations, comparison with other procedures, and numerical tests are presented.

    ↳ physics.plasm-phastro-ph.HEhep-phphysics.comp-phPhys.Plasmas(2022)·2 citations
17. 17*

    Superluminal propagation from IR physics

    Asuka Ito🇯🇵 · Teruaki Suyama🇯🇵

    One may believe that front velocities of waves in a given theory coincide with the UV limit of phase velocities for any dispersion relations. This implies that IR physics is irrelevant to the discussion of propagation speed of waves. We first consider a theory that contains higher spatial derivatives in the wave equation and prove that front velocities coincide with the UV limit of phase velocities, at least, if parity is conserved. However, we also show that front velocities do not coincide with the UV limit of phase velocities in general dispersion relations. We explicitly give several examples in which front velocities are superluminal owing to an IR or intermediate energy scale property of dispersion relations even if the UV limit of phase velocities is luminal. Our finding conveys the important caution that not only UV physics but also IR physics can be significant to superluminality.

    ↳ hep-thhep-phPRD(2023)·0 citations
18. 18*

    Light nuclei production in pp and pA collisions in the Baryon Canonical Ensemble

    Natasha Sharma🇮🇳 · Lokesh Kumar🇮🇳 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱

    The increase in yields of light nuclei with charged particle multiplicity, as reported by the ALICE collaboration at CERN in p-p and p-Pb collisions at the LHC energy is investigated in the thermal hadron resonance gas model. The model is extended to account for exact baryon number conservation. The focus is on the production of protons, deuterons, ${}^3$He, and ${}_{\Lambda }^3$H. A very good description of proton and deuteron yields is obtained as a function of charged particle multiplicity in the mid-rapidity region using the same fixed temperature as in central Pb-Pb collisions. The yields of light nuclei ${}^3$He and ${}_{\Lambda }^3$H though qualitatively explained as a function of multiplicity, are lower than the model expectation. One of the possible reasons could be that for ${}^3$He and ${}_{\Lambda }^3$H, the chemical equilibrium is not yet reached at small multiplicities.

    ↳ nucl-thhep-phPRC(2023)·9 citations
19. 19*

    Neutrinos from the Brightest Gamma-Ray Burst?

    Kohta Murase🇺🇸 · Mainak Mukhopadhyay🇺🇸 · Ali Kheirandish🇺🇸 · Shigeo S. Kimura🇯🇵 · Ke Fang🇺🇸

    We discuss implications that can be obtained by searches for neutrinos from the brightest gamma-ray burst, GRB 221009A. We derive constraints on GRB model parameters such as the cosmic-ray loading factor and dissipation radius, taking into account both neutrino spectra and effective areas. The results are strong enough to constrain proton acceleration near the photosphere, and we find that the single burst limits are comparable to those from stacking analysis. Quasithermal neutrinos from subphotospheres and ultrahigh-energy neutrinos from external shocks are not yet constrained. We show that GeV-TeV neutrinos originating from neutron collisions are detectable, and urge dedicated analysis on these neutrinos with DeepCore and IceCube as well as ORCA and KM3NeT.

    ↳ astro-ph.HEhep-phApJL(2022)·80 citations
20. 20*

    Renormalization Group for Non-minimal ${\varphi }^{2}R$ Couplings and Gravitational Contact Interactions

    Dumitru Ghilencea🇷🇴 · Christopher T. Hill🇺🇸

    Theories of scalars and gravity, with an Einstein-Hilbert term and non-minimal interactions, $M^{2}R/2-\alpha {\varphi }^{2}R/12$, have graviton exchange induced contact interactions. These modify the renormalization group, leading to a discrepancy between the conventional calculations in the Jordan frame that ignore this effect (and are found to be incorrect), and the Einstein frame in which $\alpha$ does not exist. Thus, the calculation of quantum effects in the Jordan and Einstein frames does not generally commute with the transition from the Jordan to the Einstein frame. In the Einstein frame, though $\alpha$ is absent, for small steps in scale $\delta \mu /\mu$ infinitesimal contact terms $\sim \delta \alpha$ are induced, that are then absorbed back into other couplings by the contact terms. This modifies the $\beta$-functions in the Einstein frame. We show how correct results can be obtained in a simple model by including this effect.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2023)·13 citations
21. 21*

    Centrality dependence of proton and light nuclei yields as a consequence of baryon annihilation in the hadronic phase

    Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸

    The centrality dependence of the $p/\pi$ ratio measured by the ALICE Collaboration in 5.02 TeV Pb-Pb collisions indicates a statistically significant suppression with the increase of the charged particle multiplicity once the centrality-correlated part of the systematic uncertainty is eliminated from the data. We argue that this behavior can be attributed to baryon annihilation in the hadronic phase. By implementing the $B\bar{B}\leftrightarrow 5\pi$ reaction within a generalized partial chemical equilibrium framework, we estimate the annihilation freeze-out temperature at different centralities, which decreases with increasing charged multiplicity and yields $T_{\mathrm{ann}}=132\pm 5$ MeV in 0-5% most central collisions. This value is considerably below the hadronization temperature of $T_{\mathrm{had}}\sim 160$ MeV but above the thermal (kinetic) freeze-out temperature of $T_{\mathrm{kin}}\sim 100$ MeV. Baryon annihilation reactions thus remain relevant in the initial stage of the hadronic phase but freeze out before (pseudo-)elastic hadronic scatterings. One experimentally testable consequence of this picture is a suppression of various light nuclei to proton ratios in central collisions of heavy ions.

    ↳ nucl-thhep-phnucl-exPLB(2022)·16 citations
22. 22*

    QFT in AdS instead of LSZ

    Balt C. van Rees🇫🇷 · Xiang Zhao🇫🇷

    The boundary correlation functions for a QFT in a fixed AdS background should reduce to S-matrix elements in the flat-space limit. We consider this procedure in detail for four-point functions. With minimal assumptions we rigorously show that the resulting S-matrix element obeys a dispersion relation, the non-linear unitarity conditions, and the Froissart-Martin bound. QFT in AdS thus provides an alternative route to fundamental QFT results that normally rely on the LSZ axioms.

    ↳ hep-thhep-phPRL(2023)·53 citations
23. 23*

    Angular Momentum Loss Due to Tidal Effects in the Post-Minkowskian Expansion

    Carlo Heissenberg🇸🇪

    We calculate the tidal corrections to the loss of angular momentum in a two-body collision at leading Post-Minkowskian order from an amplitude-based approach. The eikonal operator allows us to efficiently combine elastic and inelastic amplitudes, and captures both the contributions due to genuine gravitational-wave emissions and those due to the static gravitational field. We calculate the former by harnessing powerful collider-physics techniques such as reverse-unitarity, thereby reducing them to cut two-loop integrals, and validate the result with an independent calculation in the Post-Newtonian limit. For the latter, we can employ the results of arXiv:2203.11915 where static-field effects were calculated for generic gravitational scattering events using the leading soft graviton theorem.

    ↳ hep-thgr-qchep-phPRL(2023)·36 citations
24. 24*

    Impact of freeze-in on dark matter isocurvature

    Nicola Bellomo🇺🇸 · Kim V. Berghaus🇺🇸 · Kimberly K. Boddy🇺🇸

    Dark matter freeze-in is a compelling cosmological production mechanism in which all or some of the observed abundance of dark matter is generated through feeble interactions it has with the Standard Model. In this work we present the first analysis of freeze-in dark matter fluctuations and consider two benchmark models: freeze-in through the direct decay of a heavy vector boson and freeze-in through pair annihilation of Standard Model particles in the thermal bath. We provide a theoretical framework for determining the impact of freeze-in on curvature and dark matter isocurvature perturbations. We determine freeze-in dark matter fluid properties from first principles, tracking its evolution from its relativistic production to its final cold state, and calculate the evolution of the dark matter isocurvature perturbation. We find that in the absence of initial isocurvature, the freeze-in production of dark matter does not source isocurvature. However, for an initial isocurvature perturbation seeded by inflation, the nonthermal freeze-in process may allow for a fraction of the isocurvature to persist, in contrast to the exponential suppression it receives in the case of thermal dark matter. In either case, the evolution of the curvature mode is unaffected by the freeze-in process. We show sensitivity projections of future cosmic microwave background experiments to the amplitude of uncorrelated, totally anticorrelated, and totally correlated dark matter isocurvature perturbations. From these projections, we infer the sensitivity to the abundance of freeze-in dark matter that sustains some fraction of the primordial isocurvature.

    ↳ astro-ph.COhep-phhep-thJCAP(2023)·17 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.