Wed·Sep 7, 2022Wednesday·September 7, 2022

1. 01*

   Enhanced $B_q\to \ell {\ell }^{\prime }$ and $B\to (K,\pi )\ell {\ell }^{\prime }$ in light of $(g-2{)}_{\mu }$

   Wei-Shu Hou🇹🇼 · Girish Kumar🇹🇼 · Sven Teunissen🇹🇼

   We study lepton flavor violating (LFV) $B$ decays in a general two Higgs doublet model with sub-TeV exotic scalars. Two different parameter spaces are explored: one dominated by extra top Yukawa coupling ${\rho }_{tt}$, the other by LFV couplings relevant for the muon $g-2$ anomaly. In the first case, flavor constraints such as $\ell \to {\ell }^{\prime }\gamma$, $h\to \ell {\ell }^{\prime }$ imply LFV $B$ decays are far below experimental sensitivities. The second case needs to be close to the alignment limit, but $B_q\to \tau \mu$ and $B\to (K,\pi )\tau \mu$ rates can lie within the sensitivities of Belle II and LHCb Upgrade II. Neutral $B$ meson mixings and $B,K,\pi \to \ell \nu$ decays provide important flavor constraints on parameter space. $B$ decays involving $e$-$\tau$ violation are constrained by $\mu \to e$ processes.

   hep-phPRD(2023)·3 citations
2. 02*

   Determination of the structure of the $K\to \pi \pi \pi$ amplitudes from recent data

   G. D'Ambrosio🇮🇹 · M. Knecht🇫🇷 · S. Neshatpour🇮🇹

   This Letter provides a new determination of the ten real coefficients that describe the structure of the $K\to \pi \pi \pi$ amplitudes in the limit where isospin is conserved and complex phases, due to either CP violation or final-state rescattering, are neglected. This determination is obtained through a fit to the data on the Dalitz-plot structures and partial-decay rates collected during the last twenty years by several high-precision experiments. The fitting procedure and the way the experimental data have been handled in the fit are discussed in detail. Our fit leads to a more precise determination of the coefficients describing the linear and quadratic slopes of the $K\to \pi \pi \pi$ amplitudes.

   hep-phPLB(2022)·19 citations
3. 03*

   Anisotropic pressure of magnetized quark matter with anomalous magnetic moment

   Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳 · Pradip Roy🇮🇳 · Sourav Sarkar🇮🇳

   We investigate magnetic field $(eB)$ dependence of constituent quark mass, the longitudinal and transverse pressure as well as the magnetization and magnetic susceptibility of strongly interacting quark matter. We employ the two-flavour Polyakov Nambu--Jona-Lasinio model with the inclusion of the anomalous magnetic moment (AMM) of the quarks at finite temperature $(T)$ and finite quark chemical potential $({\mu }_q)$ capturing different stages of chiral phase transition. We find that the transverse pressure, magnetization and magnetic susceptibility become highly oscillatory for large values of $eB$ in the chiral symmetry broken phase. However the oscillations cease to occur at higher values of $T$ and ${\mu }_q$ when chiral symmetry is (partially) restored and the anisotropic nature of the pressure becomes significant even at smaller values of $eB$. As the inclusion of AMM of the quarks leads to inverse magnetic catalysis of the transition temperature we observe that the variations of transverse pressure, magnetization and magnetic susceptibility are significantly modified in the vicinity of the chiral transition temperature. Furthermore, above the chiral transition temperature the magnetic susceptibility is found to remain positive for a wide range of $eB$ indicating a paramagnetic character of the strongly interacting quark matter. Finally, we have also examined the magnetism of strongly interacting matter in the quarkyonic phase. The obtained results could be useful for a magnetohydrodynamic evolution of hot and dense matter created in heavy-ion collisions.

   hep-phnucl-thPRD(2022)·22 citations
4. 04*

   Forward-backward asymmetry induced $CP$ asymmetry of $B^{\pm }\to {\pi }^{\pm }{\pi }^{+}{\pi }^{-}$

   Ya-Rui Wei🇨🇳 · Zhen-Hua Zhang🇨🇳

   $CP$ violation of the decay $B^{\pm }\to {\pi }^{\pm }{\pi }^{+}{\pi }^{-}$ in the $f_0(500)-\rho (770{)}^0$ interfering region is analyzed. The forward-backward asymmetries (FBAs) and the corresponding $CP$ asymmetries FB-$CP$As are particularly investigated. To isolate the $CP$V caused by the interference of different partial wave more cleanly, we also introduce the direct-$CP$V-subtracted FB-$CP$A. Based on the LHCb data, we extract the FBAs, FB-$CP$As, direct-$CP$V-subtracted FB-$CP$A, as well as the regional $CP$As with invariant mass of the ${\pi }^{+}{\pi }^{-}$ pair in the range 0.2 GeV/$c^2<\sqrt{s_{\text{low}}}<1.8$ GeV/$c^2$. It is found that the (direct-$CP$V-subtracted) FB-$CP$As are quite large in the $f_0(500)-\rho (770{)}^0$ interfering region, which confirms that the interference of the intermediate resonances $f_0(500)$ and $\rho (770{)}^0$ plays an important role for the $CP$ violation of the three-body decay channel $B^{\pm }\to {\pi }^{\pm }{\pi }^{+}{\pi }^{-}$.

   hep-phhep-exPRD(2022)·9 citations
5. 05*

   Quark-model relations among TMDs in the parton model

   F. Aslan🇺🇸 · S. Bastami🇺🇸 · A. Mahabir🇺🇸 · A. Tandogan🇺🇸 · P. Schweitzer🇺🇸

   The covariant parton model (CPM) is a consequent application of the parton model concept to the nucleon structure. In this model, there is a choice to put quarks either in a pure-spin state or in a mixed-spin state. We show that the mixed-spin version of the CPM does not support the quark-model relations among transverse momentum dependent parton distributions (TMDs) which were shown to hold in a large class of quark models. One can enforce the quark-model relations to be valid in the CPM by imposing a condition which is equivalent to putting the quarks in a pure-spin state. This gives a complementary perspective on the connection of the pure- and mixed-spin state CPM versions, and provides a fresh view on the question whether the quark-model relations could be realized in QCD as "approximate relations" with some useful numerical accuracy.

   hep-phnucl-thPRD(2022)·4 citations
6. 06*

   Coupling Constant $g_{{\Lambda }_b{B}_s\Lambda }$ using the Baryonic ${\bar{B}}_s^0\to p\bar{\Lambda }{K}^{-}$ Decay

   S. Rafibakhsh🇮🇷 · H. Mehraban🇮🇷

   We study the three-body baryonic B decay ${\bar{B}}_s^0\to p\bar{\Lambda }{K}^{-}$ within the framework of the pole model via the baryonic ${\Lambda }_b$ pole. In our calculation, we require the strong coupling constant $g_{{\Lambda }_b{B}_s\Lambda }$ and investigate if $g_{{\Lambda }_b{B}_s\Lambda }=10.49\pm 1.57$ is adopted, the branching ratio agrees with the experimental result, reported by the LHCb collaboration.

   hep-ph0 citations
7. 07*

   In-medium properties of light vector and axial-vector mesons: effects of Dirac sea

   Pallabi Parui🇮🇳 · Amruta Mishra🇮🇳

   The in-medium masses of the light vector, ${\rho }^{0,\pm }$, $\omega$ and the light axial-vector, $A_1^{0,\pm }$ mesons, are studied in the magnetized nuclear matter, accounting for the effects of the Dirac sea. The in-medium partial decay widths for the $A_1\to \rho \pi$ channels, are studied from the in-medium masses of the initial and the final state particles, by applying a phenomenological Lagrangian to account for the $A_1\rho \pi$ interaction vertices. The masses calculated within the QCD sum rule framework, are obtained in terms of the light quark ($\sim ⟨\bar{q}q⟩$) and the scalar gluon condensates ($\sim ⟨G^2⟩$), as well as the light four-quark condensate ($\sim ⟨\bar{q}q{⟩}^2$). The condensates are calculated within the chiral $SU(3)$ model in terms of the medium modified scalar fields. The effects of magnetic fields are incorporated through the Landau energy levels of protons, anomalous magnetic moments (AMMs) of the nucleons in the nuclear matter, in addition to the magnetized Dirac sea contribution, within the chiral effective model. The enhancement (reduction) of the light quark condensates with magnetic field, is called (inverse) magnetic catalysis. The effects of magnetic fields on the in-medium hadronic decay widths of the $A_1$ mesons, are observed to be significant through the Dirac sea effect, accounting for the AMMs of the nucleons. This may affect the light mesons production in the non-central, heavy-ion collision experiments, where estimated magnetic field is very large.

   hep-ph6 citations
8. 08*

   Cross-channel constraints on resonant antikaon-nucleon scattering

   Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳 · Michael Doering🇺🇸 · Maxim Mai🇺🇸

   Chiral perturbation theory and its unitarized versions have played an important role in our understanding of the low-energy strong interaction. Yet, so far, such studies typically deal exclusively with perturbative or nonperturbative channels. In this letter, we report on the first global study of meson-baryon scattering up to one-loop order. It is shown that covariant baryon chiral perturbation theory, including its unitarization for the negative strangeness sector, can describe meson-baryon scattering data remarkably well. This provides a highly non-trivial check on the validity of this important low-energy effective field theory of QCD. We show that the $\bar{K}N$ related quantities can be better described in comparison with those of lower-order studies, and with reduced uncertainties due to the stringent constraints from the $\pi N$ and $KN$ phase shifts. In particular, we find that the two-pole structure of $\Lambda (1405)$ persists up to one-loop order reinforcing the existence of two-pole structures in dynamically generated states.

   hep-phhep-exnucl-exnucl-thPRL(2023)·60 citations
9. 09*

   Enhancement of Direct $CP$ asymmetry in $Z^{\prime }$ models

   Shireen Niteen Gangal🇮🇳

   We consider $CP$-violating $Z^{\prime }$ models to account for the anomalies in $b\to s\ell \ell$ decays. Using the updated constraints from lepton flavor universality (LFU) violating ratios, $b\to s\mu \mu$ $CP$-conserving and $CP$-violating observables, $B_s-{\bar{B}}_s$ mixing and neutrino trident we obtain the favored parameter space of two classes of $Z^{\prime }$ models generating the `1D' new physics scenarios with $C_9^{\mathrm{NP}}<0$ and $C_9^{\mathrm{NP}}=-C_{10}^{\mathrm{NP}}$. We show that the predictions of direct $CP$ asymmetry $A_{CP}$ in $B^{+}\to K^{+}\mu \mu$ decays close to the $c\bar{c}$ resonance region can be used to detect the presence of new $CP$ violating phases in the $Z^{\prime }$ couplings.The favored $1\sigma$ parameter space of $Z^{\prime }$ models generating the scenario $C_9^{\mathrm{NP}}<0$ allows for an enhancement in the integrated $A_{CP}$ in $q^2=[8,9]\mathrm{Ge}{\mathrm{V}}^2$ bin up to $\pm 10\%$ and in the $q^2=[6,7]\mathrm{Ge}{\mathrm{V}}^2$ bin up to $\pm 5\%$. We find that for a negative value of the phase of $J/\psi$ resonance, although such an enhancement is possible in $Z^{\prime }$ models generating the scenario $C_9^{\mathrm{NP}}=-C_{10}^{\mathrm{NP}}$, the favored parameter space prefers only positive values of $A_{CP}$. Hence, a future measurement of direct $CP$ asymmetry in these bins can potentially constrain the size of new $CP$ violating phases, and help in distinguishing between the two classes of $Z^{\prime }$ models.

   hep-phPRD(2024)·6 citations
10. 10*

    Constraint of $\xi$-moments calculated with QCD sum rules on the pion distribution amplitude models

    Tao Zhong🇨🇳 · Zhi-Hao Zhu🇨🇳 · Hai-Bing Fu🇨🇳

    So far, the behavior of the pionic leading-twist distribution amplitude (DA) ${\varphi }_{2;\pi }(x,\mu )$ $-$ which is universal physical quantity and enters the high-energy processes involving pion based on the factorization theorem $-$ has not been completely consistent. The form of ${\varphi }_{2;\pi }(x,\mu )$ is usually described by phenomenological models and constrained by the experimental data of the exclusive processes containing pion or the moments calculated with the QCD sum rules and lattice QCD theory. Obviously, an appropriate model is very important for us to determine the exact behavior of ${\varphi }_{2;\pi }(x,\mu )$. In this paper, by adopting the least squares method to fit the $\xi$-moments calculated with QCD sum rules based on the background field theory, we perform an analysis for several commonly used models of the pionic leading-twist DA in the literature, such as the truncation form of the Gegenbauer polynomial series, the light-cone harmonic oscillator model, the form from the Dyson-Schwinger equations, the model from the light-front holographic AdS/QCD and a simple power-law parametrization form.

    hep-phCPC(2023)·10 citations
11. 11*

    Probing CP Violation in Neutrino-antineutrino Oscillations with Non-unitary Flavor Mixing

    Yilin Wang🇨🇳 · Shun Zhou🇨🇳

    If massive neutrinos are Majorana particles, then the lepton number should be violated and neutrino-antineutrino oscillations will take place. In this talk, we present the properties of CP violation in neutrino-antineutrino oscillations with a non-unitary leptonic flavor mixing matrix, which naturally arises in the type-I seesaw model due to the mixing between light and heavy Majorana neutrinos. Taking into account current experimental bounds on the leptonic unitarity violation, we show that the CP asymmetries induced by the non-unitary mixing parameters can significantly deviate from those in the unitarity limit.

    hep-phPoS(2022)·0 citations
12. 12*

    Synchrotron radiation by slowly rotating fermions

    Matteo Buzzegoli🇺🇸 · Jonathan D. Kroth🇺🇸 · Kirill Tuchin🇺🇸 · Nandagopal Vijayakumar🇺🇸

    We study the synchrotron radiation emitted by a charged fermion, rotating as a part of a larger system, in a constant magnetic field $B$ parallel to the axis of rotation. The rotation is classical and independent of the magnetic field. The angular velocity of rotation $\Omega$ is assumed to be much smaller than the inverse magnetic length $\sqrt{qB}$ which allows us to ignore the boundary effects at $r=1/\Omega$. We refer to such rotation as slow, even though in absolute value it may be an extremely rapid rotation. Using the exact solution of the Dirac equation we derived the intensity of electromagnetic radiation, its spectrum and chirality. We demonstrate by explicit numerical calculation that the effect of rotation on the radiation intensity increases with the particle energy. Depending on the relative orientation of the vectors $\mathbf{\Omega }$ and $\mathbf{B}$ and the sign of the electric charge, the rotation can either strongly enhance or strongly suppress the radiation.

    hep-phastro-ph.HEhep-thPRD(2023)·11 citations
13. 13*

    Resonant leptoquark at NLO with POWHEG

    Luca Buonocore🇨🇭 · Admir Greljo🇨🇭 · Peter Krack🇨🇭 · Paolo Nason🇮🇹 · Nudzeim Selimovic🇨🇭 · Francesco Tramontano🇮🇹 · Giulia Zanderighi🇩🇪

    Recent progress in calculating lepton density functions inside the proton and simulating lepton showers laid the foundations for precision studies of resonant leptoquark production at hadron colliders. Direct quark-lepton fusion into a leptoquark is a novel production channel at the LHC that has the potential to probe a unique parameter space for large masses and couplings. In this work, we build the first Monte Carlo event generator for a full-fledged simulation of this process at NLO for production, followed by a subsequent decay using the POWHEG method and matching to the parton showers utilizing HERWIG. The code can handle all scalar leptoquark models with renormalisable quark-lepton interactions. We then comprehensively study the differential distributions, including higher-order effects, and asses the corresponding theoretical uncertainties. We also quantify the impact of the improved predictions on the projected (HL-)LHC sensitivities and initiate the first exploration of the potential at the FCC-hh. Our work paves the way toward performing LHC searches using this channel.

    hep-phJHEP(2022)·26 citations
14. 14*

    Generalized quasi, Ioffe-time, and pseudo quark distributions of the pion in the Nambu--Jona-Lasinio model

    Vanamali Shastry🇵🇱 · Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸

    We analyze the generalized quasi, Ioffe-time, and pseudo distributions of the valence quarks in the pion at the quark model scale. We use the framework of the Nambu-Jona-Lasinio model and investigate the basic question of how fast the pion has to move to effectively reach the infinite momentum limit, where the approach can provide the information on the generalized parton distribution functions. We consider both the vector distributions and the transversity distributions, related to the spin densities. With the developed analytic expressions, we conclude that to effectively approach the infinite momentum limit, one roughly needs the pion momenta of the order of $\sim 3$GeV. We also explore polynomiality of the quasi distributions and study the generalized quasi form factors. The issue of separability of the transverse and longitudinal dynamics in the model is studied with the help of the generalized Ioffe-time distributions, with the conclusion that the breaking is not substantial, unless the momentum transfer $t$ is large. We also provide an estimate of the range of the Ioffe-time values needed to obtain the generalized parton distributions with a reasonable accuracy. Our model results, which are analytic or semi-analytic, provide a valuable insight into the theoretical formalism and illustrate the intricate features of the investigated distributions.

    hep-phhep-latPRD(2022)·15 citations
15. 15*

    Spacelike thermal correlators are almost time-independent

    Simon Caron-Huot🇨🇦 · Guy D. Moore🇩🇪

    We show that, in relativistic field theories, the thermal correlation function of N bosonic operators <O_1(x_1,t_1) O_2(x_2,t_2) .. O_N(x_N,t_N)> at sufficiently spacelike-separated points shows exponentially weak dependence on the time variables t_1,...,t_N, when the space separations are held fixed. For classical thermal field theory, the time dependence vanishes when all points are spacelike separated

    hep-phPRD(2022)·7 citations
16. 16*

    Blazar constraints on neutrino-dark matter scattering

    James M. Cline🇨🇦 · Shan Gao🇨🇦 · Fangyi Guo🇨🇦 · Zhongan Lin🇨🇦 · Shiyan Liu🇨🇦 · Matteo Puel🇨🇦 · Phillip Todd🇨🇦 · Tianzhuo Xiao🇨🇦

    Neutrino emission in coincidence with gamma rays has been observed from the blazar TXS 0506+056 by the IceCube telescope. Neutrinos from the blazar had to pass through a dense spike of dark matter (DM) surrounding the central black hole. The observation of such a neutrino implies new upper bounds on the neutrino-DM scattering cross section as a function of DM mass. The constraint is stronger than existing ones for a range of DM masses, if the cross section rises linearly with energy. For constant cross sections, competitive bounds are also possible, depending on details of the DM spike.

    hep-phastro-ph.COastro-ph.HEPRL(2023)·68 citations
17. 17*

    Neutrino masses, flavor anomalies and muon $\mathbf{g}-2$ from dark loops

    Ricardo Cepedello🇩🇪 · Pablo Escribano🇪🇸 · Avelino Vicente🇪🇸

    The lepton sector of the Standard Model is at present haunted by several intriguing anomalies, including an emerging pattern of deviations in $b\to s\ell \ell$ processes, with hints of lepton flavor universality violation, and a discrepancy in the muon anomalous magnetic moment. More importantly, it cannot explain neutrino oscillation data, which necessarily imply the existence of non-zero neutrino masses and lepton mixings. We propose a model that accommodates all the aforecited anomalies, induces neutrino masses and provides a testable dark matter candidate. This is achieved by introducing a dark sector contributing to the observables of interest at the 1-loop level. Our setup provides a very economical explanation to all these open questions in particle physics and is compatible with the current experimental constraints.

    hep-phPRD(2023)·13 citations
18. 18*

    Love symmetry

    Panagiotis Charalambous🇺🇸 · Sergei Dubovsky🇺🇸 · Mikhail M. Ivanov🇺🇸

    Perturbations of massless fields in the Kerr-Newman black hole background enjoy a (``Love'') SL$(2,\mathbb{R})$ symmetry in the suitably defined near zone approximation. We present a detailed study of this symmetry and show how the intricate behavior of black hole responses in four and higher dimensions can be understood from the SL$(2,\mathbb{R})$ representation theory. In particular, static perturbations of four-dimensional black holes belong to highest weight SL$\left(2,\mathbb{R}\right)$ representations. It is this highest weight property that forces the static Love numbers to vanish. We find that the Love symmetry is tightly connected to the enhanced isometries of extremal black holes. This relation is simplest for extremal charged spherically symmetric (Reissner-Nordström) solutions, where the Love symmetry exactly reduces to the isometry of the near horizon AdS${}_2$ throat. For rotating (Kerr-Newman) black holes one is lead to consider an infinite-dimensional SL$\left(2,\mathbb{R}\right)⋉\hat{U}(1{)}_{\mathcal{V}}$ extension of the Love symmetry. It contains three physically distinct subalgebras: the Love algebra, the Starobinsky near zone algebra, and the near horizon algebra that becomes the Bardeen-Horowitz isometry in the extremal limit. We also discuss other aspects of the Love symmetry, such as the geometric meaning of its generators for spin weighted fields, connection to the no-hair theorems, non-renormalization of Love numbers, its relation to (non-extremal) Kerr/CFT correspondence and prospects of its existence in modified theories of gravity.

    ↳ hep-thastro-ph.HEgr-qchep-phJHEP(2022)·117 citations
19. 19*

    Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization

    Volodymyr Biloshytskyi🇩🇪 · En-Hung Chao🇩🇪 · Antoine Gérardin🇫🇷 · Jeremy R. Green🇮🇪 · Franziska Hagelstein🇩🇪 · Harvey B. Meyer🇩🇪 · Julian Parrino🇩🇪 · Vladimir Pascalutsa🇩🇪

    Lattice QCD calculations of the hadronic vacuum polarization (HVP) have reached a precision where the electromagnetic (e.m.) correction can no longer be neglected. This correction is both computationally challenging and hard to validate, as it leads to ultraviolet (UV) divergences and to sizeable infrared (IR) effects associated with the massless photon. While we precisely determine the UV divergence using the operator-product expansion, we propose to introduce a separation scale $\Lambda \sim 400$MeV into the internal photon propagator, whereby the calculation splits into a short-distance part, regulated in the UV by the lattice and in the IR by the scale $\Lambda$, and a UV-finite long-distance part to be treated with coordinate-space methods, thereby avoiding power-law finite-size effects altogether. In order to predict the long-distance part, we express the UV-regulated e.m. correction to the HVP via the forward hadronic light-by-light (HLbL) scattering amplitude and relate the latter via a dispersive sum rule to ${\gamma }^{\ast }{\gamma }^{\ast }$ fusion cross-sections. Having tested the relation by reproducing the two-loop QED vacuum polarization (VP) from the tree-level ${\gamma }^{\ast }{\gamma }^{\ast }\to e^{+}{e}^{-}$ cross-section, we predict the expected lattice-QCD integrand resulting from the ${\gamma }^{\ast }{\gamma }^{\ast }\to {\pi }^0$ process.

    ↳ hep-lathep-phJHEP(2023)·31 citations
20. 20*

    Anomalous transport from equilibrium partition functions

    Eugenio Megias🇪🇸

    We summarize recent advances in the application of the equilibrium partition function formalism for the study of the transport coefficients of relativistic fluids induced by quantum anomalies, at first and second order in the hydrodynamic expansion. We provide results for theories with Abelian and non-Abelian chiral fermions, and discuss some features of the corresponding constitutive relations.

    ↳ hep-thcond-mat.str-elhep-phNucl.Part.Phys.Proc.(2023)·0 citations
21. 21*

    Static spherical vacuum solutions in the bumblebee gravity model

    Rui Xu🇨🇳 · Dicong Liang🇨🇳 · Lijing Shao🇨🇳

    The bumblebee gravity model is a vector-tensor theory of gravitation where the vector field nonminimally couples to the Ricci tensor. By investigating the vacuum field equations with spherical symmetry, we find two families of black-hole (BH) solutions in this model: one has a vanishing radial component of the vector field and the other has a vanishing radial component of the Ricci tensor. When the coupling between the vector field and the Ricci tensor is set to zero, the first family becomes the Reissner-Nordström solution while the second family degenerates to the Schwarzschild solution with the vector field being zero. General numerical solutions in both families are obtained for nonzero coupling between the vector field and the Ricci tensor. Besides BH solutions, we also reveal the existence of solutions that have a nonvanishing $tt$-component of the metric on the supposed event horizon where the $rr$-component of the metric diverges while the curvature scalars are finite. These solutions are not supported by existing observations but present certain properties that are of academic interests. We conclude the study by putting the BH solutions into tests against the Solar-system observations and the images of supermassive BHs.

    ↳ gr-qchep-phhep-thphysics.comp-phPRD(2023)·108 citations
22. 22*

    Scale-invariant enhancement of gravitational waves during inflation

    Atsuhisa Ota🇨🇳 · Misao Sasaki🇯🇵 · Yi Wang🇨🇳

    The inflationary 1-loop tensor power spectrum from an excited spectator scalar field is calculated. Recent studies on primordial black holes suggest that the inflationary curvature perturbation may be huge on small scales. An enhanced curvature perturbation may arise from a drastic enhancement of spectator scalar field fluctuations. In this letter, using the in-in formalism, we calculate 1-loop quantum corrections to primordial gravitational waves by such an excited spectator field with a sharp peak in momentum space. We find scale-invariant loop corrections in this full quantum setup, in contrast to the sharply peaked corrections in the previously calculated scalar-induced tensor modes. Especially, on super Hubble scales, the primordial gravitational waves are also amplified, which can be understood as a Bogolyubov transformation of the vacuum due to the excited scalar field. This mechanism allows us to probe the scalar field properties on extremely short-distance scales with the current and future cosmic microwave background and gravitational wave experiments, opening a novel window for inflationary cosmology.

    ↳ astro-ph.COgr-qchep-phhep-thMod.Phys.Lett.A(2023)·28 citations
23. 23*

    "Pseudo-Conformal" Sound Speed in the Core of Compact Stars

    Mannque Rho🇫🇷

    We present the argument that "pseudo-conformal" symmetry permeates from low density near nuclear matter to high density in the core of massive neutron stars. As a support of this argument, we describe how the quenched $g_A\approx 1$ in nuclei and the sound speed $v_s^2/c^2\approx 1/3$ in compact stars are controlled by emerging scale invariance in nuclear interactions. In our description, quasi-baryons could "masquerade" de-confined quarks in the interior of compact stars.

    ↳ nucl-thastro-ph.HEhep-phSymmetry(2022)·13 citations
24. 24*

    Holographic model for the first order phase transition in the composite Higgs boson scenario

    Oleg O. Novikov🇷🇺 · Andrey A. Shavrin🇷🇺

    The composite Higgs model assumes that the Higgs field arises as the pseudo-Goldstone mode corresponding to a dynamical symmetry breaking in a new strongly coupled sector. We present a soft-wall holographic model where such symmetry breaking occurs as a first order phase transition. In this case the bubble nucleation in the early universe becomes possible. To study the homogeneous solutions in the models of this type we present the perturbation theory approach. We estimate the gravitational wave spectrum produced during the nucleation phase and find it to be detectable with the planned gravitational wave detectors.

    ↳ hep-thgr-qchep-phPRD(2023)·2 citations
25. 25*

    Non-minimally coupled Natural Inflation: Palatini and Metric formalism with the recent BICEP/Keck

    Nilay Bostan🇺🇸

    In this work, we show the effect of the non-minimal coupling $\xi {\varphi }^{2}R$ on the inflationary parameters by considering the single-field inflation and present the inflationary predictions of the appealing potential for the particle physics viewpoint: Natural Inflation, an axion-like inflaton which has a cosine-type periodic potential and the inflaton naturally emerges as a pseudo-Nambu-Goldstone boson with a spontaneously broken global symmetry. We present the inflationary predictions for this potential, $n_s$, $r$, and $\alpha =\mathrm{d}{n}_s/\mathrm{d}\ln k$. In addition, we assume standard thermal history after inflation, and using this, for considered potential, we show compatible regions for the $n_s$, $r$ within the recent BICEP/Keck results.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2023)·17 citations
26. 26*

    Non-perturbative production of fermionic dark matter from fast preheating

    Juraj Klaric🇧🇪 · Andrey Shkerin🇺🇸 · Georgios Vacalis🇬🇧

    We investigate non-perturbative production of fermionic dark matter in the early universe. We study analytically the gravitational production mechanism accompanied by the coupling of fermions to the background inflaton field. The latter leads to the variation of effective fermion mass during preheating and makes the resulting spectrum and abundance sensitive to its parameters. Assuming fast preheating that completes in less than the inflationary Hubble time and no oscillations of the inflaton field after inflation, we find an abundant production of particles with energies ranging from the inflationary Hubble rate to the inverse duration of preheating. The produced fermions can account for all observed dark matter in a broad range of parameters. As an application of our analysis, we study non-perturbative production of heavy Majorana neutrino in the model of Palatini Higgs inflation.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2023)·11 citations
27. 27*

    A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck

    Juan S. Cruz🇩🇰 · Florian Niedermann🇸🇪 · Martin S. Sloth🇩🇰

    We examine further the ability of the New Early Dark Energy model (NEDE) to resolve the current tension between the Cosmic Microwave Background (CMB) and local measurements of $H_0$ and the consequences for inflation. We perform new Bayesian analyses, including the current datasets from the ground-based CMB telescopes Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT), and the BICEP/Keck telescopes, employing an updated likelihood for the local measurements coming from the S$H_0$ES collaboration. Using the S$H_0$ES prior on $H_0$, the combined analysis with Baryonic Acoustic Oscillations (BAO), Pantheon, Planck and ACT improves the best-fit by $\Delta {\chi }^2=-15.9$ with respect to $\Lambda$CDM, favors a non-zero fractional contribution of NEDE, $f_{\mathrm{NEDE}}>0$, by $4.8\sigma$, and gives a best-fit value for the Hubble constant of $H_0=72.09$ km/s/Mpc (mean $71.48_{-0.81}^{+0.79}$ with $68\%$ C.L.). A similar analysis using SPT instead of ACT yields consistent results with a $\Delta {\chi }^2=-23.1$ over $\Lambda$CDM, a preference for non-zero $f_{\mathrm{NEDE}}$ of $4.7\sigma$ and a best-fit value of $H_0=71.77$ km/s/Mpc (mean $71.43_{-0.84}^{+0.84}$ with $68\%$ C.L.). We also provide the constraints on the inflation parameters $r$ and $n_s$ coming from NEDE, including the BICEP/Keck 2018 data, and show that the allowed upper value on the tensor-scalar ratio is consistent with the $\Lambda$CDM bound, but, as also originally found, with a more blue scalar spectrum implying that the simplest curvaton model is now favored over the Starobinsky inflation model.

    ↳ astro-ph.COhep-phhep-thJCAP(2023)·43 citations

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