Fri·Jul 9, 2021Friday·July 9, 2021

1. 01*

   Axion-like particles from primordial black holes shining through the Universe

   Francesco Schiavone (Bari Univ.)🇮🇹 · Daniele Montanino (Lecce Univ. & INFN Lecce)🇮🇹 · Alessandro Mirizzi (Bari Univ. & INFN Bari)🇮🇹 · Francesco Capozzi (Virginia Tech.)🇺🇸

   We consider a cosmological scenario in which the very early Universe experienced a transient epoch of matter domination due to the formation of a large population of primordial black holes (PBHs) with masses $M\lesssim 10^9\text{g}$, that evaporate before Big Bang nucleosynthesis. In this context, Hawking radiation would be a non-thermal mechanism to produce a cosmic background of axion-like particles (ALPs). We assume the minimal scenario in which these ALPs couple only with photons. In the case of ultralight ALPs ($m_a\lesssim 10^{-9}\text{eV}$) the cosmic magnetic fields might trigger ALP-photon conversions, while for masses $m_a\gtrsim 10\text{eV}$ spontaneous ALP decay in photon pairs would be effective. We investigate the impact of these mechanisms on the cosmic X-ray background, on the excess in X-ray luminosity in Galaxy Clusters, and on the process of cosmic reionization.

   hep-phastro-ph.COJCAP(2021)·41 citations
2. 02*

   New leptons with exotic decays: collider limits and dark matter complementarity

   Guilherme Guedes🇪🇸 · José Santiago🇪🇸

   We describe current and future hadron collider limits on new vector-like leptons with exotic decays. We consider the possibility that, besides standard decays, the new leptons can also decay into a Standard Model charged lepton and a stable particle like a dark photon. To increase their applicability, our results are given in terms of arbitrary branching ratios in the different decay channels. In the case that the dark photon is stable at cosmological scales we discuss the interplay between the dark photon and the vector-like lepton in generating the observed dark matter relic abundance and the complementarity of collider searches and dark matter phenomenology.

   hep-phJHEP(2022)·53 citations
3. 03*

   Vector-meson production and vector meson dominance

   Yin-Zhen Xu🇨🇳 · Si-Yang Chen🇨🇳 · Zhao-Qian Yao🇨🇳 · Daniele Binosi🇮🇹 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇨🇳

   We consider the fidelity of the vector meson dominance (VMD) assumption as an instrument for relating the electromagnetic vector-meson production reaction $e+p\to e^{\prime }+V+p$ to the purely hadronic process $V+p\to V+p$. Analyses of the photon vacuum polarisation and the photon-quark vertex reveal that such a VMD Ansatz might be reasonable for light vector-mesons. However, when the vector-mesons are described by momentum-dependent bound-state amplitudes, VMD fails for heavy vector-mesons: it cannot be used reliably to estimate either a photon-to-vector-meson transition strength or the momentum dependence of those integrands that would arise in calculations of the different reaction amplitudes. Consequently, for processes involving heavy mesons, the veracity of both cross-section estimates and conclusions based on the VMD assumption should be reviewed, e.g., those relating to hidden-charm pentaquark production and the origin of the proton mass.

   hep-phhep-exhep-latnucl-ex+1EPJC(2021)·66 citations
4. 04*

   Decay processes of a pseudoscalar $D(2900)$

   Brenda B. Malabarba🇧🇷 · K. P. Khemchandani🇧🇷 · A Martinez Torres🇧🇷

   We study the decay properties of a $D(2900)$ state, with spin-parity $0^{-}$, whose existence was proposed in an earlier study of the $DK\bar{K}$ and coupled channel system. It was found in the former work that a $D$-meson appears with a mass of about 2900 MeV from the three-body dynamics while the charmless subsystem of the pseudoscalar mesons forms the $f_0(980)$ resonance. Motivated by the recent experimental investigations of $D$-mesons around 3000 MeV, we now study the two-body decays of $D(2900)$. We find that the nature of the said state sets the main decay channels to be $D^{\ast }\pi$, $D_s^{\ast }\bar{K}$ and $D_{s0}^{\ast }(2317)\bar{K}$. It turns out that decay width to the last one is the largest, making the $D_{s0}^{\ast }(2317)\bar{K}$ system to be the most favorable one to look for a signal of $D(2900)$. We compare the decay properties of our state with those of the $D$-meson states, proposed within quark models, near 3000 MeV. We hope that our findings and discussions can be useful for the future experimental investigations of charm mesons around 3000 MeV.

   hep-phPRD(2021)·5 citations
5. 05*

   Densities of States and the CKN Bound

   Nikita Blinov🇺🇸 · Patrick Draper🇺🇸

   The holographic principle implies that quantum field theory overcounts the number of independent degrees of freedom in quantum gravity. An argument due to Cohen, Kaplan, and Nelson (CKN) suggests that the number of degrees of freedom well-described by QFT is even smaller than required by holographic bounds, and CKN interpreted this result as indicative of a correlation between the UV and IR cutoffs on QFT. Here we consider an alternative interpretation in which the QFT degrees of freedom are depleted as a function of scale. We use a simple recipe to estimate the impact of depleted densities of states on precision observables, including the Lamb shift and lepton $g-2$. Although these observables are not sensitive to the level of depletion motivated by gravitational considerations, the phenomenological exercises also provide an interesting test of quantum field theory that is independent of underlying quantum gravity assumptions. A depleted density of states can also render the QFT vacuum energy UV-insensitive, reconciling the success of QFT in describing ordinary particle physics processes and its apparent failure in predicting the cosmological constant.

   hep-phhep-thPRD(2021)·26 citations
6. 06*

   Study muon g-2 at two-loop level in the $U(1{)}_X$SSM

   Shu-Min Zhao🇨🇳 · Lu-Hao Su🇨🇳 · Xing-Xing Dong🇨🇳 · Tong-Tong Wang🇨🇳 · Tai-Fu Feng🇨🇳

   The new experiment data of muon g-2 is reported by the workers at Fermilab National Accelerator Laboratory(FNAL). Combined with the previous Brookhaven National Laboratory(BNL) E821 result, the departure from the standard model prediction is about 4.2 $\sigma$. It strengthens our faith in the new physics. $U(1{)}_X$SSM is the U(1) extension of the minimal supersymmetric standard model, where we study the electroweak corrections to the anomalous magnetic dipole moment of muon from the one-loop diagrams and some two-loop diagrams possessing important contributions. These two-loop diagrams include Barr-Zee type, rainbow type and diamond type. The virtual supersymmetric particles in these two-loop diagrams are chargino, scalar neutrino, neutralino, scalar lepton, which are supposed not very heavy to make relatively large corrections. We obtain the Wilson coefficients of the dimension 6 operators inducing the anomalous magnetic dipole moment of muon. The numerical results can reach $25\times 10^{-10}$ and even larger.

   hep-phJHEP(2022)·36 citations
7. 07*

   Semileptonic $B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\bar{\nu }}_{\ell }$ decay with $\pi \pi$ invariant mass spectrum

   Shang-Yuu Tsai🇨🇳 · Yu-Kuo Hsiao🇨🇳

   BELLE has recently reported the measurement of the branching fraction of the semileptonic $B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\bar{\nu }}_{\ell }$ decay, where $\ell$ represents an electron or a muon. With the new information on the $\pi \pi$ invariant mass spectrum, we extract $|V_{ub}|=(3.31\pm 0.61)\times 10^{-3}$ in agreement with those from the other exclusive $B$ decays. In particular, we determine the non-resonant $B\to \pi \pi$ transition form factors, and predict the non-resonant branching fraction $\mathcal{B}(B^{-}\to {\pi }^{+}{\pi }^{-}{\ell }^{-}{\bar{\nu }}_{\ell })=(3.5\pm 1.4_{-2.4}^{+4.3})\times 10^{-5}$, which is accessible to the BELLEII and LHCb experiments.

   hep-phhep-exCPC(2026)·9 citations
8. 08*

   Power corrections and gradient expansion in QED transport theory

   Stefano Carignano🇪🇸 · Cristina Manuel🇪🇸

   The hard thermal loop (HTL) effective field theory of QED can be derived from the classical limit of transport theory, corresponding to the leading term in a gradient expansion of the quantum approach. In this paper, we show that power corrections to the HTL effective Lagrangian of QED can also be obtained from transport theory by including higher orders in such gradient expansion. The gradient expansion is increasingly infrared (IR) divergent, but the correction that we compute is IR finite. We employ dimensional regularization, and show that this result comes after a cancellation of divergencies between the vacuum and medium contributions. While the transport framework is an effective field theory of the long distance physics of the plasma, we show that it correctly reproduces the correct QED ultraviolet divergencies associated with the photon wave function renormalization.

   hep-phPRD(2021)·6 citations
9. 09*

   The decay $\tau \to K^{-}\eta {\nu }_{\tau }$ in the extended Nambu-Jona-Lasinio model taking into account the meson interaction in the final state

   M. K. Volkov🇷🇺 · A. A. Pivovarov🇷🇺

   The branching fraction of the decay $\tau \to K^{-}\eta {\nu }_{\tau }$ has been calculated by using the extended Nambu-Jona-Lasinio model taking into account the meson interaction in the final state. The contact term and the channel with the intermediate ground $K^{\ast }(892)$ and first radially excited state $K^{\ast }(1410)$ have been calculated. For the purpose of describing the meson interaction in the final state, the triangle diagram with three mesons has been considered. The cutoff parameter of divergent integrals of the meson loop is equal to the appropriate parameter used in our previous work to describe the decay $\tau \to K^{-}{\pi }^0{\nu }_{\tau }$. Thereby, the present work does not set any additional arbitrary parameters. The obtained results are in satisfactory agreement with the experimental data.

   hep-phPisma Zh.Eksp.Teor.Fiz.(2021)·2 citations
10. 10*

    Diluting quark flavor hierarchies using dihedral symmetry

    Ayushi Srivastava🇮🇳 · Miguel Levy🇵🇹 · Dipankar Das🇮🇳

    We present a $D_4$ flavored extension of the SM which provides an intuitive reasoning for the masses and mixing patterns in the quark sector. In our model, the Cabibbo mixing angle stems purely from the scalar sector dynamics. In fact, the orders of magnitude of the CKM matrix elements are readily obtained from the hierarchical nature of the vacuum expectation values. Moreover, we also show that the smallness of the off-Cabibbo elements in the CKM matrix is strongly connected to the heaviness of the third generation of quarks.

    hep-phEPJC(2022)·3 citations
11. 11*

    Photoproduction of possible pentaquark states ${\Lambda }_b^0(5912)$ and ${\Lambda }_b^0(5920)$ in the $\gamma p\to {\Lambda }_b^{0(\ast )}{B}^{+}$ reactions

    Yin Huang🇨🇳 · Hong Qiang Zhu🇨🇳

    In this work, we report on a theoretical study of possible pentaquark states ${\Lambda }_b^0(5912)$ and ${\Lambda }_b^0(5920)$ in the $\gamma p\to {\Lambda }_b^{0(\ast )}{B}^{+}$ reactions within an effective Lagrangian approach. In addition to the contributions from the $s$-channel nucleon pole and $t$-channel ${\bar{B}}^{\ast -}$ exchange, the contact term contribution are also included. Our theoretical approach is based on the chiral unitary theory where the ${\Lambda }_b^0(5912)$ and ${\Lambda }_b^0(5920)$ resonances are dynamically generated. Within the coupling constants of the ${\Lambda }_b^0(5912)$ and ${\Lambda }_b^0(5920)$ to $\bar{B}p$ and ${\bar{B}}^{\ast }p$ channels obtained from chiral unitary theory, the total and differential cross sections of the $\gamma p\to {\Lambda }_b^{0(\ast )}{B}^{+}$ are evaluated. Our calculation indicates that the cross section for $\gamma p\to {\Lambda }_b^0(5912)B^{+}$ and $\gamma p\to {\Lambda }_b^0(5920)B^{+}$ reactions are of the order of 0.0164 nb and 0.00527 nb,respectively. If measured in future experiments, such as Electron-Ion Collider in China (EicC) or US(US-EIC), the predicted total cross sections and specific features of the angular distributions can be used to test the (molecular) nature of the ${\Lambda }_b^0(5912)$ and ${\Lambda }_b^0(5920)$ that they may be pentaquark states.

    hep-phPRD(2021)·8 citations
12. 12*

    Zooming in on eV-MeV Scale Sterile Neutrinos in light of Neutrinoless Double Beta Decay

    Tapoja Jha🇮🇳 · Sarif Khan🇩🇪 · Manimala Mitra🇮🇳 · Ayon Patra🇮🇳

    The existence of light sterile neutrinos, as predicted in several models, can help to explain a number of observations starting from dark mater to recent anomalies in short baseline experiments. In this paper we consider two models - Left-Right Symmetric Zee model and Extended Seesaw model, that can naturally accommodate the presence of light sterile neutrinos in the eV to MeV mass scale. We perform a detailed study on the neutrinoless double beta decay process which receives major contributions from diagrams involving these light sterile neutrinos. Considering a number of theoretical and experimental constraints, including light neutrino masses and mixings, unitarity of the mixing matrix etc., we compare our predicted values of the half-life of neutrinoless double beta decay with the experimental limits. This can put significant constraints on the neutrino mass, active-sterile neutrino mixing and several other important parameters in these models.

    hep-phhep-exPRD(2022)·6 citations
13. 13*

    QED factorization of two-body non-leptonic and semi-leptonic $B$ to charm decays

    Martin Beneke🇩🇪 · Philipp Böer🇩🇪 · Gael Finauri🇩🇪 · K. Keri Vos🇳🇱

    The QCD$\times$QED factorization is studied for two-body non-leptonic and semi-leptonic $B$ decays with heavy-light final states. These non-leptonic decays, like ${\bar{B}}_{(s)}^0\to D_{(s)}^{+}{\pi }^{-}$ and ${\bar{B}}_d^0\to D^{+}{K}^{-}$, are among the theoretically cleanest non-leptonic decays as penguin loops do not contribute and colour-suppressed tree amplitudes are suppressed in the heavy-quark limit or even completely absent. Advancing the theoretical calculations of such decays requires therefore also a careful analysis of QED effects. Including QED effects does not alter the general structure of factorization which is analogous for both semi-leptonic and non-leptonic decays. For the latter, we express our result as a correction of the tree amplitude coefficient $a_1$. At the amplitude level, we find QED effects at the sub-percent level, which is of the same order as the QCD uncertainty. We discuss the phenomenological implications of adding QED effects in light of discrepancies observed between theory and experimental data, for ratios of non-leptonic over semi-leptonic decay rates. At the level of the rate, ultrasoft photon effects can produce a correction up to a few percent, requiring a careful treatment of such effects in the experimental analyses.

    hep-phJHEP(2021)·54 citations
14. 14*

    Non-Abelian Electric Field Correlator at NLO for Dark Matter Relic Abundance and Quarkonium Transport

    Tobias Binder🇯🇵 · Kyohei Mukaida🇯🇵 · Bruno Scheihing-Hitschfeld🇺🇸 · Xiaojun Yao🇺🇸

    We perform a complete next-to-leading order calculation of the non-Abelian electric field correlator in a SU($N_c$) plasma, which encodes properties of the plasma relevant for heavy particle bound state formation and dissociation, and is different from the correlator for the heavy quark diffusion coefficient. The calculation is carried out in the real-time formalism of thermal field theory and includes both vacuum and finite temperature contributions. By working in the $R_{\xi }$ gauge, we explicitly show the results are gauge independent, infrared and collinear safe. The renormalization group equation of this electric field correlator is determined by that of the strong coupling constant. Our next-to-leading order calculation can be directly applied to any dipole singlet-adjoint transition of heavy particle pairs. For example, it can be used to describe dissociation and (re)generation of heavy quarkonia inside the quark-gluon plasma well below the melting temperature, as well as heavy dark matter pairs (or charged co-annihilating partners) in the early universe.

    hep-phastro-ph.COnucl-thJHEP(2022)·56 citations
15. 15*

    Is the existence of a $J/\psi J/\psi$ bound state plausible?

    Xiang-Kun Dong🇨🇳 · Vadim Baru🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Alexey Nefediev🇷🇺 · Bing-Song Zou🇨🇳

    In a recent measurement LHCb reported pronounced structures in the $J/\psi J/\psi$ spectrum. One of the various possible explanations of those is that they emerge from non-perturbative interactions of vector charmonia. It is thus important to understand whether it is possible to form a bound state of two charmonia interacting through the exchange of gluons, which hadronise into two pions at the longest distance. In this paper, we demonstrate that, given our current understanding of hadron-hadron interactions, the exchange of correlated light mesons (pions and kaons) is able to provide sizeable attraction to the di-$J/\psi$ system, and it is possible for two $J/\psi$ mesons to form a bound state. As a side result we find from an analysis of the data for the $\psi (2S)\to J/\psi \pi \pi$ transition including both $\pi \pi$ and $K\bar{K}$ final state interactions an improved value for the $\psi (2S)\to J/\psi$ transition chromo-electric polarisability: $|{\alpha }_{\psi (2S)J/\psi }|=(1.8\pm 0.1)\text{mbox}{GeV}^{-3}$, where the uncertainty also includes the one induced by the final state interactions.

    hep-phhep-exhep-latSci.Bull.(2021)·66 citations
16. 16*

    Dirac Masses and Mixings in the (geo)SM(EFT) and Beyond

    Jim Talbert🇩🇰 · Michael Trott🇩🇰

    We report a set of exact formulae for computing Dirac masses, mixings, and CP-violation parameter(s) from 3$\times$3 Yukawa matrices $Y$ valid when $Y{Y}^{†}\to U^{†}Y{Y}^{†}U$ under global $U(3{)}_{Q_L}$ flavour symmetry transformations $U$. The results apply to the Standard Model Effective Field Theory (SMEFT) and its `geometric' realization (geoSMEFT). We thereby complete, in the Dirac flavour sector, the catalogue of geoSMEFT parameters derived at all orders in the $\sqrt{2⟨H^{†}H⟩}/\Lambda$ expansion. The formalism is basis-independent, and can be applied to models with decoupled ultraviolet flavour dynamics, as well as to models whose infrared dynamics are not minimally flavour violating. We highlight these points with explicit examples and, as a further demonstration of the formalism's utility, we derive expressions for the renormalization group flow of quark masses, mixings, and CP-violation at all mass dimension and perturbative loop orders in the (geo)SM(EFT) and beyond.

    hep-phJHEP(2021)·12 citations
17. 17*

    Charged Higgs Prospects In Extended Gauge Models

    Baradhwaj Coleppa🇮🇳 · Gokul B. Krishna🇮🇳 · Agnivo Sarkar🇮🇳

    In this paper, we explore the collider phenomenology of the charged Higgs boson in the context of a generic Beyond Standard Model scenario with extended gauge and scalar sectors. In such scenarios, the charged Higgs boson can decay via the $W^{{}^{\prime }}Z/W{Z}^{{}^{\prime }}$ channels. We formulate a search strategy for the $H^{\pm }$ in the channel $\sigma (gb\to H^{\pm }t)\mathcal{B}\mathcal{R}(H^{\pm }\to W^{\prime }Z)$ considering the interesting cascade decay chain $H^{\pm }\to W^{{}^{\prime }}Z\to W^{\pm }ZZ$. We find that the charged Higgs can be discovered in final states with multiple hard leptons and/ or b-quarks which future LHC experiments with sufficiently large luminosity ($\mathcal{L}=1000f{b}^{-1}$ and above) can probe.

    hep-phEPJC(2023)·3 citations
18. 18*

    Complementarity between dark matter direct searches and CE$\nu$NS experiments in $U(1{)}^{\prime }$ models

    Leon M. G. de la Vega🇲🇽 · L. J. Flores🇲🇽 · Newton Nath🇲🇽 · Eduardo Peinado🇲🇽

    We explore the possibility of having a fermionic dark matter candidate within $U(1{)}^{\prime }$ models for CE$\nu$NS experiments in light of the latest COHERENT data and the current and future dark matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under $U(1{)}^{\prime }$ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CE$\nu$NS experiments and dark matter direct detection searches to explore dark matter as well as $Z^{\prime }$ boson parameter space. Depending on numerous other constraints arising from the beam dump, LHCb, BABAR, and the forthcoming reactor experiment proposed by the SBC collaboration, we explore the allowed region of $Z^{\prime }$ portal dark matter.

    hep-phhep-exJHEP(2021)·43 citations
19. 19*

    Novel constraints on fifth forces and ultralight dark sector with asteroidal data

    Yu-Dai Tsai🇺🇸 · Youjia Wu🇺🇸 · Sunny Vagnozzi🇮🇹 · Luca Visinelli🇨🇳

    We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a new gauge field (dark photon) or a baryon-coupled scalar, we estimate the sensitivity reach for the fifth force coupling strength and mediator mass in the mass range $m\simeq (10^{-21}-10^{-15})\mathrm{eV}$, near the ``fuzzy'' dark matter region. Our estimated sensitivity is comparable to leading limits from equivalence principle tests, potentially exceeding these in a specific mass range. Furthermore, we set new constraints on Yukawa gravity. The fifth force-induced precession increases with the orbital semi-major axis in the limit of a small mass $m$, motivating the study of objects further away from the Sun. We discuss future prospects for extending our study to more than a million asteroids, including NEOs, main-belt asteroids, Hildas, and Jupiter Trojans, as well as trans-Neptunian objects and exoplanets.

    hep-phastro-ph.COastro-ph.EPgr-qcJCAP(2023)·51 citations
20. 20*

    A Large-$N$ Expansion for Minimum Bias

    Andrew J. Larkoski🇺🇸 · Tom Melia🇯🇵

    Despite being the overwhelming majority of events produced in hadron or heavy ion collisions, minimum bias events do not enjoy a robust first-principles theoretical description as their dynamics are dominated by low-energy quantum chromodynamics. In this paper, we present a novel expansion scheme of the cross section for minimum bias events that exploits an ergodic hypothesis for particles in the events and events in an ensemble of data. We identify power counting rules and symmetries of minimum bias from which the form of the squared matrix element can be expanded in symmetric polynomials of the phase space coordinates. This expansion is entirely defined in terms of observable quantities, in contrast to models of heavy ion collisions that rely on unmeasurable quantities like the number of nucleons participating in the collision, or tunes of parton shower parameters to describe the underlying event in proton collisions. The expansion parameter that we identify from our power counting is the number of detected particles $N$ and as $N\to \infty$ the variance of the squared matrix element about its mean, constant value on phase space vanishes. With this expansion, we show that the transverse momentum distribution of particles takes a universal form that only depends on a single parameter, has a fractional dispersion relation, and agrees with data in its realm of validity. We show that the constraint of positivity of the squared matrix element requires that all azimuthal correlations vanish in the $N\to \infty$ limit at fixed center-of-mass energy, as observed in data. The approach we follow allows for a unified treatment of small and large system collective behavior, being equally applicable to describe, e.g., elliptic flow in PbPb collisions and the "ridge" in pp collisions.

    hep-phhep-exhep-thnucl-ex+1JHEP(2021)·7 citations
21. 21*

    Two A4 modular symmetries for Tri-Maximal 2 mixing

    Ivo de Medeiros Varzielas🇵🇹 · João Lourenço🇵🇹

    We construct lepton flavour models based on two $A_4$ modular symmetries. The two $A_4$ are broken by a bi-triplet field to the diagonal $A_4$ subgroup, resulting in an effective modular $A_4$ flavour symmetry with two moduli. We employ these moduli as stabilisers, that preserve distinct residual symmetries, enabling us to obtain Tri-Maximal 2 (TM2) mixing with a minimal field content (without flavons).

    hep-phNPB(2022)·35 citations
22. 22*

    Uncovering an Axion Mechanism with the EDM Portfolio

    Jordy de Vries🇳🇱 · Patrick Draper🇺🇸 · Kaori Fuyuto🇺🇸 · Jonathan Kozaczuk🇺🇸 · Benjamin Lillard🇺🇸

    Effective field theory arguments suggest that if BSM sectors contain new sources of CP-violation that couple to QCD, these sources will renormalize the $\theta$ term and frustrate ultraviolet solutions to the strong CP problem. Simultaneously, they will generate distinctive patterns of low-energy electric dipole moments in hadronic, nuclear, atomic, and molecular systems. Observing such patterns thus provides evidence that strong CP is solved by an infrared relaxation mechanism. We illustrate the renormalization of $\theta$ and the collections of EDMs generated in a several models of BSM physics, confirming effective field theory expectations, and demonstrate that measurements of ratios of electric dipole moments at planned experiments can provide valuable input on the resolution of the strong CP problem.

    hep-phhep-exPRD(2021)·29 citations
23. 23*

    Strong clustering of primordial black holes from Affleck-Dine mechanism

    Masahiro Kawasaki🇯🇵 · Kai Murai🇯🇵 · Hiromasa Nakatsuka🇯🇵

    Primordial black hole (PBH) is a fascinating candidate for the origin of binary merger events observed by LIGO-Virgo collaboration. The spatial distribution of PBHs at formation is an important feature to estimate the merger rate. We investigate the clustering of PBHs formed by Affleck-Dine (AD) baryogenesis, where dense baryon bubbles collapse to form PBHs. We found that formed PBHs show a strong clustering due to the stochastic dynamics of the AD field. Including the clustering, we evaluate the merger rate and isocurvature perturbations of PBHs, which show significant deviations from those without clustering.

    ↳ astro-ph.COhep-phJCAP(2021)·15 citations
24. 24*

    Analytic Tadpole Coefficients of One-loop Integrals

    Bo Feng🇨🇳 · Tingfei Li🇨🇳 · Xiaodi Li🇨🇳

    One remaining problem of unitarity cut method for one-loop integral reduction is that tadpole coefficients can not be straightforward obtained through this way. In this paper, we reconsider the problem by applying differential operators over an auxiliary vector $R$. Using differential operators, we establish the corresponding differential equations for tadpole coefficients at the first step. Then using the tensor structure of tadpole coefficients, we transform the differential equations to the recurrence relations for undetermined tensor coefficients. These recurrence relations can be solved easily by iteration, and we can obtain analytic expressions of tadpole coefficients for arbitrary one-loop integrals.

    ↳ hep-thhep-phJHEP(2021)·23 citations
25. 25*

    Memory efficient finite volume schemes with twisted boundary conditions

    Eduardo I. Bribian🇪🇸 · Jorge Luis Dasilva Golan🇪🇸 · Margarita Garcia Perez🇪🇸 · Alberto Ramos🇪🇸

    In this paper we explore a finite volume renormalization scheme that combines three main ingredients: a coupling based on the gradient flow, the use of twisted boundary conditions and a particular asymmetric geometry, that for $SU(N)$ gauge theories consists on a hypercubic box of size $l^2\times (Nl{)}^2$, a choice motivated by the study of volume independence in large $N$ gauge theories. We argue that this scheme has several advantages that make it particularly suited for precision determinations of the strong coupling, among them translational invariance, an analytic expansion in the coupling and a reduced memory footprint with respect to standard simulations on symmetric lattices, allowing for a more efficient use of current GPU clusters. We test this scheme numerically with a determination of the $\Lambda$ parameter in the $SU(3)$ pure gauge theory. We show that the use of an asymmetric geometry has no significant impact in the size of scaling violations, obtaining a value ${\Lambda }_{\overline{MS}}\sqrt{8t_0}=0.603(17)$ in good agreement with the existing literature. The role of topology freezing, that is relevant for the determination of the coupling in this particular scheme and for large $N$ applications, is discussed in detail.

    ↳ hep-lathep-phhep-thEPJC(2021)·15 citations
26. 26*

    Proton number fluctuations in partial chemical equilibrium

    Boris Tomasik🇨🇿 · Paula Hillmann🇩🇪 · Marcus Bleicher🇩🇪

    We calculate volume-independent ratios of cumulants of the net-proton number distribution up to sixth order in a fireball that cools down after the chemical freeze-out. A hadron resonance gas model is used together with the assumption of partial chemical equilibrium, which fixes the number of observed stable hadrons after the chemical freeze-out. It is shown that due to only weak departure from the statistical Boltzmann distribution, also the volume-independent ratios of higher-order cumulants of the net-proton number show only weak dependence on the temperature. This observation supports the possibility to measure non-critical cumulants at chemical freeze-out even after subsequent cooling in the hadronic phase. Cumulants of the net-baryon number behave similarly, while those for the kaon number vary more strongly with the temperature. Our results are relevant for the current fluctuation studies of the RHIC-BES runs.

    ↳ nucl-thhep-phPRC(2021)·6 citations
27. 27*

    The weak-gravity bound and the need for spin in asymptotically safe matter-gravity models

    Gustavo P. de Brito🇩🇰 · Astrid Eichhorn🇩🇰 · Rafael Robson Lino dos Santos🇩🇰

    We discover a weak-gravity bound in scalar-gravity systems in the asymptotic-safety paradigm. The weak-gravity bound arises in these systems under the approximations we make, when gravitational fluctuations exceed a critical strength. Beyond this critical strength, gravitational fluctuations can generate complex fixed-point values in higher-order scalar interactions. Asymptotic safety can thus only be realized at sufficiently weak gravitational interactions. We find that within truncations of the matter-gravity dynamics, the fixed point lies beyond the critical strength, unless spinning matter, i.e., fermions and vectors, is also included in the model.

    ↳ gr-qchep-phhep-thJHEP(2021)·50 citations
28. 28*

    Three-body dynamics of the $a_1(1260)$ resonance from lattice QCD

    Maxim Mai🇺🇸 · Andrei Alexandru🇺🇸 · Ruairí Brett🇺🇸 · Chris Culver🇬🇧 · Michael Döring🇺🇸 · Frank X. Lee🇺🇸 · Daniel Sadasivan🇺🇸

    Resonant hadronic systems often exhibit a complicated decay pattern in which three-body dynamics play a relevant or even dominant role. In this work we focus on the $a_1(1260)$ resonance. For the first time, the pole position and branching ratios of a three-body resonance are calculated from lattice QCD using one-, two-, and three-meson interpolators and a three-body finite-volume formalism extended to spin and coupled channels. This marks a new milestone for ab-initio studies of ordinary resonances along with hybrid and exotic hadrons involving three-body dynamics.

    ↳ hep-lathep-phnucl-thPRL(2021)·78 citations
29. 29*

    Asymmetric reheating from a symmetric inflationary potential

    James M. Cline🇨🇦 · Jean-Samuel Roux🇨🇦

    We explore a model of two-field inflation with nonminimal kinetic terms in which two identical matter sectors decoupled from each other may reheat to different temperatures while preserving the symmetry of the Lagrangian. This scenario is motivated by mirror dark matter models in which the temperature of the mirror sector is constrained to be $T^{\prime }\lesssim 0.5T$ by big bang nucleosynthesis and the cosmic microwave background. For a given class of nonminimal kinematic terms, we find that the symmetric field trajectory $X=Y$ is a repeller solution, such that any randomly-occurring asymmetry in the initial conditions is amplified by many orders of magnitude during inflation, far beyond what canonical power-law models can achieve. Isocurvature fluctuations are strongly suppressed in this model, but a $\mathcal{O}(0.03$--$0.07$) tensor-to-scalar ratio could be observed in the near future. The range of potential parameters compatible with {\it Planck} constraints is shown to be much larger than in corresponding single-field models. This occurs through a mechanism for lowering the spectral index that we dub CTHC: curved trajectory at horizon crossing.

    ↳ astro-ph.COhep-phPRD(2022)·8 citations
30. 30*

    Scale-invariance, dynamically induced Planck scale and inflation in the Palatini formulation

    Ioannis D. Gialamas🇬🇷 · Alexandros Karam🇪🇪 · Thomas D. Pappas🇨🇿 · Antonio Racioppi🇪🇪 · Vassilis C. Spanos🇬🇷

    We present two scale invariant models of inflation in which the addition of quadratic in curvature terms in the usual Einstein-Hilbert action, in the context of Palatini formulation of gravity, manages to reduce the value of the tensor-to-scalar ratio. In both models the Planck scale is dynamically generated via the vacuum expectation value of the scalar fields.

    ↳ gr-qchep-phhep-thJ.Phys.Conf.Ser.(2021)·18 citations
31. 31*

    Non-conformal attractor in boost-invariant plasmas

    Chandrodoy Chattopadhyay🇺🇸 · Sunil Jaiswal🇮🇳 · Lipei Du🇺🇸 · Ulrich Heinz🇺🇸 · Subrata Pal🇮🇳

    We study the dissipative evolution of (0+1)-dimensionally expanding media with Bjorken symmetry using the Boltzmann equation for massive particles in relaxation-time approximation. Breaking conformal symmetry by a mass induces a non-zero bulk viscous pressure in the medium. It is shown that even a small mass (in units of the local temperature) drastically modifies the well-known attractor for the shear Reynolds number previously observed in massless systems. For generic nonzero particle mass, neither the shear nor the bulk viscous pressure relax quickly to a non-equilibrium attractor; they approach the hydrodynamic limit only late, at small values of the inverse Reynolds numbers. Only the longitudinal pressure, which is a combination of thermal, shear and bulk viscous pressures, continues to show early approach to a far-off-equilibrium attractor, driven by the rapid longitudinal expansion at early times. Second-order dissipative hydrodynamics based on a gradient expansion around locally isotropic thermal equilibrium fails to reproduce this attractor.

    ↳ nucl-thhep-phphysics.plasm-phPLB(2022)·62 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.