Tue·Sep 22, 2020Tuesday·September 22, 2020

1. 01*

   Missing Member of the $J^{PC}=2^{--}$ Nonet in Extreme Conditions

   J. Y. Süngü🇹🇷 · A. Türkan🇹🇷 · E. Sertbakan🇹🇷 · E. Veli Veliev🇹🇷

   The isoscalar member of the axial-tensor family that should take place in the further states of the PDG is still absent. In this study, analyzes are made as to whether one of the X states whose quantum numbers are unknown in this group, is a candidate for the missing resonance under the assignment $2^3{D}_2$. Moreover, replacing the time evolution operator with the thermal average one, we construct the modified correlator satisfying Thermal QCD sum rules approach. We determine that the hadronic parameters of the considered nonet member are sensitive to the increment of temperature. This knowledge can be helpful to complete the $J^{PC}=2^{--}$ light meson nonet and also explore the hot medium behaviors at upcoming heavy-ion collision experiments.

   hep-ph0 citations
2. 02*

   Fast oscillations, collisionless relaxation, and spurious evolution of supernova neutrino flavor

   Lucas Johns🇺🇸 · Hiroki Nagakura🇺🇸 · George M. Fuller🇺🇸 · Adam Burrows🇺🇸

   Mounting evidence indicates that neutrinos likely undergo fast flavor conversion (FFC) in at least some core-collapse supernovae. Outcomes of FFC, however, remain highly uncertain. Here we study the cascade of flavor-field power from large angular scales in momentum space down to small ones, showing that FFC enhances this process and thereby hastens relaxation. Cascade also poses a computational challenge, which is present even if the flavor field is stable: When power reaches the smallest angular scale of the calculation, error from truncating the angular-moment expansion propagates back to larger scales, to disastrous effect on the overall evolution. Essentially the same issue has prompted extensive work in the context of plasma kinetics. This link suggests new approaches to averting spurious evolution, a problem that presently puts severe limitations on the feasibility of realistic oscillation calculations.

   hep-phastro-ph.HEPRD(2020)·82 citations
3. 03*

   CP Violating $h{W}^{+}{W}^{-}$ Coupling in the Standard Model and Beyond

   Da Huang🇨🇳 · António P. Morais🇵🇹 · Rui Santos🇵🇹

   Inspired by the recent development in determining the property of the observed Higgs boson, we explore the $CP$-violating (CPV) $-c_{\mathrm{CPV}}h{W}^{+\mu \nu }{\tilde{W}}_{\mu \nu }^{-}/v$ coupling in the Standard Model (SM) and beyond, where $W^{\pm \mu \nu }$ and ${\tilde{W}}^{\pm \mu \nu }$ denote the $W$-boson field strength and its dual. To begin with, we show that the leading-order SM contribution to this CPV vertex appears at two-loop level. By summing over the quark flavor indices in the two loop integrals analytically, we can estimate the order of the corresponding Wilson coefficient to be $c_{\mathrm{CPV}}^{\mathrm{SM}}\sim \mathcal{O}(10^{-23})$, which is obviously too small to be probed at the LHC and planned future colliders. Then we investigate this CPV $h{W}^{+}{W}^{-}$ interaction in two Beyond the Standard Model benchmark models: the left-right model and the complex 2-Higgs doublet model (C2HDM). Unlike what happens for the SM, the dominant contributions in both models arise at the one-loop level, and the corresponding Wilson coefficient can be as large as of $\mathcal{O}(10^{-9})$ in the former model and of $\mathcal{O}(10^{-3})$ for the latter. In light of such a large CPV effect in the $h{W}^{+}{W}^{-}$ coupling, we also give the formulae for the leading one-loop contribution to the related CPV $hZZ$ effective operator in the C2HDM. The order of magnitude of the Wilson coefficients in the C2HDM may be within reach of the high-luminosity LHC or planned future colliders.

   hep-phhep-exJHEP(2021)·9 citations
4. 04*

   The mass splitting in an 331-TC coupled Scenario

   A. Doff🇧🇷

   The root of most of the technicolor (TC) problems lies in the way the ordinary fermions acquire their masses, where an ordinary fermion (f) couples to a technifermion (F) mediated by an Extended Technicolor (ETC) boson leading to fermion masses that vary with the ETC mass scale ($M_E$) as $1/M_E^2$. Recently, we discussed a new approach consisting of models where TC and QCD are coupled through a larger theory, in this case the solutions of these equations are modified compared to those of the isolated equations, and TC and QCD self-energies are of the Irregular form, which allows us to build models where ETC boson masses can be pushed to very high energies. In this work we extend these results for 331-TC models, in particular considering a coupled system of Schwinger-Dyson equations, we show that all technifermions of the model exhibit the same asymptotic behavior for TC self-energies. As an application we discuss how the mass splitting of the order $O(100)GeV$ could be generated between the second and third generation of fermions.

   hep-phInt.J.Mod.Phys.A(2020)·0 citations
5. 05*

   Chiral Symmetry Restoration and Deconfinement in the Contact Interaction Model of Quarks with a Parallel Electric and Magnetic Fields

   Aftab Ahmad🇵🇰

   We study the impact of steady, homogeneous, and external parallel electric and magnetic field strength ($eE\parallel eB$), on the chiral symmetry breaking-restoration and confinement-deconfinement phase transitions. We also sketch the phase diagram of quantum chromodynamics (QCD) at finite temperature $T$ and in the presence of background fields. Our unified formalism for this study is based on the Schwinger-Dyson equations, symmetry preserving vector-vector contact interaction model of quarks, and the proper time regularization scheme. At $T=0$, in the purely magnetic case ($eE\to 0$), we observe the well known magnetic catalysis effect. On the other hand, in the pure electric field background ($eB\to 0$), the electric field tends to restore the chiral symmetry and deconfinement above the pseudo-critical electric field $e{E}_c^{\chi ,C}$. In the presence of both $eE$ and $eB$: we find the magnetic catalysis effect in the particular region where $eB$ dominates over $eE$, whereas, we observe the chiral inhibition (or electric chiral rotation) effect, when $eE$ stand over $eB$. At finite $T$, in the pure electric field case, the phenomenon of inverse electric catalysis appears to exist in our model. On the other hand for pure magnetic field background, we notice the magnetic catalysis effect in the mean-field approximation and inverse magnetic catalysis with $eB$-dependent coupling. The combined effect of both $eE$ and $eB$ on the pseudo-critical $T_c^{\chi ,C}$ yields the inverse electromagnetic catalysis, with and without $eB-$dependent effective coupling of the model. Our findings are satisfactory in agreement with already predicted results by lattice simulations and other reliable effective models of QCD.

   hep-phnucl-thCPC(2021)·12 citations
6. 06*

   Probing new physics in semileptonic ${\Sigma }_b$ and ${\Omega }_b$ decays

   Jin-Huan Sheng🇨🇳 · Jie Zhu🇨🇳 · Xiao-Nan Li🇨🇳 · Quan-Yi Hu🇨🇳 · Ru-Min Wang🇨🇳

   Recently, several hints of lepton non-universality have been observed in the semileptonic B meson decays in terms of both in the neutral current ($b\to sl\bar{l}$) and charged current ($b\to cl\overline{{\nu }_l}$) transitions. Motivated by these inspiring results, we perform the analysis of the baryon decays ${\Sigma }_b\to {\Sigma }_{c}l\overline{{\nu }_l}$ and ${\Omega }_b\to {\Omega }_{c}l\overline{{\nu }_l}(l=e,\mu ,\tau )$ which are mediated by $b\to cl\overline{{\nu }_l}$ transitions at the quark level, to scrutinize the nature of new physics (NP) in the model independent method. We first use the experimental measurements of $\mathcal{B}(B\to D^{(\ast )}l\overline{{\nu }_l})$, ${\mathrm{R}}_{D^{(\ast )}}$ and ${\mathrm{R}}_{J/\psi }$ to constrain the NP coupling parameters in a variety of scenarios. Using the constrained NP coupling parameters, we report numerical results on various observables related to the processes ${\Sigma }_b\to {\Sigma }_{c}l\overline{{\nu }_l}$ and ${\Omega }_b\to {\Omega }_{c}l\overline{{\nu }_l}$, such as the branching ratios, the ratio of branching fractions, the lepton side forward-backward asymmetries, the hadron and lepton longitudinal polarization asymmetries and the convexity parameter. We also provide the $q^2$ dependency of these observables and we hope that the corresponding numerical results in this work will be testified by future experiments.

   hep-phPRD(2020)·11 citations
7. 07*

   $e^{+}{e}^{-}\to hhZ$ in the B-L symmetric SSM

   Dan-Dan Cui🇨🇳 · Tai-Fu Feng🇨🇳 · Yu-Li Yan🇨🇳 · Hai-Bin Zhang🇨🇳 · Guo-Zhu Ning🇨🇳 · Jin-Lei Yang🇨🇳

   The double Higgs boson production through $e^{+}{e}^{-}\to hhZ$ is analyzed in the minimal supersymmetric extension of the Standard Model(SM) with the local gauge symmetry $U(1{)}_{B-L}$, where $h$ denotes the lightest Higgs boson with 125 GeV. Considering the constraints from the updated prediction data, we find that the production cross section of this process in the model depends on some parameters strongly.

   hep-phPRD(2020)·1 citation
8. 08*

   Flow coefficients in O-O Al-Al and Cu-Cu collisions at 200 GeV in the fusing color string model

   M.A. Braun🇷🇺 · C. Pajares🇪🇸

   In view of the planning experiments for collisions of light nuclei at RHIC the flow coefficients for O-O, Al-AL and Cu-Cu collisions are studied in the color string percolation model. Our results for $v_2$ are somewhat smaller than predicted by other groups although with the same dependence on centrality. Our obtained $v_3$ lie between predictions of other groups.

   hep-phnucl-thPRC(2021)·0 citations
9. 09*

   Physical constraints derived from FCNC in the 3-3-1-1 model

   N.T.Duy · Takeo Inami🇻🇳 · D.T.Huong

   We investigate several phenomena related to FCNCs in the $\text{3-3-1-1}$ model. The sources of FCNCs at the tree-level from both the gauge and Higgs sectors are clarified. Experiments on the oscillation of mesons most stringently constrain the tree-level FCNCs. The lower bound on the new physics scale is imposed more tightly than in the previous, ${\text{M}}_{\text{new}}>12$ \text{TeV}. Under this bound, the tree-level FCNCs make a negligible contribution to the $\text{Br}(B_s\to {\mu }^{+}{\mu }^{-})$, $\text{Br}(B\to K^{\ast }{\mu }^{+}{\mu }^{-})$ and $\text{Br}(B^{+}\to K^{+}{\mu }^{+}{\mu }^{-})$. The branching ratio of radiative decay $b\to s\gamma$ is enhanced by the ratio $\frac{v}{u}$ via diagrams with the charged Higgs mediation. In contrast, the charged currents of new gauge bosons significantly contribute to the decay process $\mu \to e\gamma$.

   hep-phEPJC(2021)·22 citations
10. 10*

    Probing anomalous quartic $\gamma \gamma \gamma \gamma$ couplings in light-by-light collisions at the CLIC

    S.C. İnan🇹🇷 · A.V. Kisselev🇷🇺

    The anomalous quartic neutral couplings of the $\gamma \gamma \gamma \gamma$ vertex in a polarized light-by-light scattering of the Compton backscattered photons at the CLIC are examined. Both differential and total cross sections are calculated for $e^{+}{e}^{-}$ collision energies 1500 GeV and 3000 GeV. The helicity of the initial electron beams is taken to be $\pm 0.8$. The unpolarized and SM cross sections for the same values of helicities are also estimated. The 95\% C.L. exclusion limits on two anomalous photon couplings ${\zeta }_1$ and ${\zeta }_2$ are calculated. The best bounds on these couplings are found to be $6.85\times 10^{-16}{\mathrm{GeV}}^{-4}$ and $1.43\times 10^{-15}{\mathrm{GeV}}^{-4}$, respectively. The results are compared with the exclusion bounds obtained previously for the LHC and HL-LHC. It is shown that the light-by-light scattering at the CLIC, especially the polarized, has a greater potential to search for the anomalous quartic neutral couplings of the $\gamma \gamma \gamma \gamma$ vertex.

    hep-phhep-exEPJC(2021)·19 citations
11. 11*

    Radiative decays of charged leptons as constraints of unitarity polygons for active-sterile neutrino mixing and CP violation

    Zhi-zhong Xing🇨🇳 · Di Zhang🇨🇳

    We calculate the rates of radiative ${\beta }^{-}\to {\alpha }^{-}+\gamma$ decays for $(\alpha ,\beta )=(e,\mu )$, $(e,\tau )$ and $(\mu ,\tau )$ by taking the {\it unitary} gauge in the $(3+n)$ active-sterile neutrino mixing scheme, and make it clear that constraints on the unitarity of the $3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix $U$ extracted from ${\beta }^{-}\to {\alpha }^{-}+\gamma$ decays in the {\it minimal unitarity violation} scheme differ from those obtained in the canonical seesaw mechanism with $n$ heavy Majorana neutrinos by a factor $5/3$. In such a natural seesaw case we show that the rates of ${\beta }^{-}\to {\alpha }^{-}+\gamma$ can be used to cleanly and strongly constrain the effective apex of a unitarity polygon, and compare its geometry with the geometry of its three sub-triangles formed by two vectors $U_{\alpha i}^{}{U}_{\beta i}^{\ast }$ and $U_{\alpha j}^{}{U}_{\beta j}^{\ast }$ (for $i\ne j$) in the complex plane. We find that the areas of such sub-triangles can be described in terms of the Jarlskog-like invariants of CP violation ${\mathcal{J}}_{\alpha \beta }^{ij}$, and their small differences signify slight unitarity violation of the PMNS matrix $U$.

    hep-phhep-exEPJC(2020)·17 citations
12. 12*

    Charge-dependent flow as evidence of strong electromagnetic fields in heavy-ion collisions

    Andrea Dubla🇩🇪 · Umut Gürsoy🇳🇱 · Raimond Snellings🇳🇱

    The extremely large electromagnetic fields generated in heavy-ion collisions provide access to novel observables that are expected to constrain various key transport properties of the quark-gluon plasma and could help solve one of the outstanding puzzles in QCD: the strong CP problem. In this review we present a brief overview of the theoretical and experimental characterization of these electromagnetic fields. After reviewing the current state, emphasising one of the observables -- the charge-dependent flow -- we discuss the various discrepancies between the measurements and theoretical predictions. Finally, to help resolve the discrepancies, we suggest new measurements and theoretical ideas.

    hep-phhep-exhep-thnucl-exMod.Phys.Lett.A(2020)·36 citations
13. 13*

    Dark Matter as a Solution to Muonic Puzzles

    Maxim Perelstein🇺🇸 · Yik Chuen San🇺🇸

    We propose a simple model in which dark matter particle exchanges mediate a new quantum force between muons and nucleons, resolving the proton charge radius puzzle. At the same time, the discrepancy between the measured anomalous magnetic moment of the muon and the Standard Model prediction can be accommodated, and thermal relic abundance of the dark matter candidate is consistent with observations. The dark matter particle mass is in the MeV range. We show that the model is consistent with a variety of experimental and observational constraints.

    hep-phPRD(2021)·7 citations
14. 14*

    Searching in 2-Dimensional Mass Space for Final States with 2 Invisible Particles

    Georgios Anagnostou🇬🇷

    A method to search for particles of unknown masses in final states with two invisible particles is presented. Searching for final states with missing energy is a challenging task usually performed in the tail of a missing energy related distribution. The search method proposed is based on a 2-Dimensional mass reconstruction of the final state with two invisible particles. Thus, a bump hunting is possible, allowing a stronger signal versus background discrimination. Parameters of the BSM theory can be extracted from the mass distributions, a valuable step towards understanding its true nature. The proof of principle of the method is based on the existing SM top pairs in their dilepton final state. Many interesting topologies including dark matter candidates or heavy top partners can be searched this way at the LHC.

    hep-phJHEP(2021)·1 citation
15. 15*

    The Data Driven Flavour Model

    Luca Merlo🇪🇸

    A bottom-up approach has been adopted to identify a flavour model that agrees with present experimental measurements. The charged fermion mass hierarchies suggest that only the top Yukawa term should be present at the renormalisable level. The flavour symmetry of the Lagrangian including the fermionic kinetic terms and only the top Yukawa is then a combination of U (2) and U(3) factors. Lighter charged fermion and active neutrino masses and quark and lepton mixings arise considering specific spurion fields. The associated phenomenology is investigated and the model turns out to have almost the same flavour protection of the Minimal Flavour Violation, in both quark and lepton sectors. Promoting the spurions to be dynamical fields, the associated scalar potential is also studied and a minimum is identified such that fermion masses and mixings are correctly reproduced.

    hep-phPoS(2021)·0 citations
16. 16*

    Quenching Mechanisms of Photon Superradiance

    Diego Blas🇬🇧 · Samuel J. Witte🇪🇸

    Rapidly rotating black holes are known to develop instabilities in the presence of a sufficiently light boson, a process which becomes efficient when the boson's Compton wavelength is roughly the size of the black hole. This phenomenon, known as black hole superradiance, generates an exponentially growing boson cloud at the expense of the rotational energy of the black hole. For astrophysical black holes with $M\sim \mathcal{O}(10)M_{\odot }$, the superradiant condition is achieved for bosons with $m_b\sim \mathcal{O}(10^{-11})\mathrm{eV}$; intriguingly, photons traversing the intergalactic medium (IGM) acquire an effective mass (due to their interactions with the ambient plasma) which naturally resides in this range. The implications of photon superradiance, i.e. the evolution of the superradiant photon cloud and ambient plasma in the presence of scattering and particle production processes, have yet to be thoroughly investigated. Here, we enumerate and discuss a number of different processes capable of quenching the growth of the photon cloud, including particle interactions with the ambient electrons and back-reactions on the effective mass (arising e.g. from thermal effects, pair-production, ionization of of the local background, and modifications to the dispersion relation from strong electric fields). This work naturally serves as a guide in understanding how interactions may allow light exotic bosons to evade superradiant constraints.

    hep-phastro-ph.COgr-qcPRD(2020)·38 citations
17. 17*

    Theoretical uncertainties for cosmological first-order phase transitions

    Djuna Croon🇨🇦 · Oliver Gould🇫🇮 · Philipp Schicho🇫🇮 · Tuomas V. I. Tenkanen🇨🇭 · Graham White🇯🇵

    We critically examine the magnitude of theoretical uncertainties in perturbative calculations of first-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertainties due to renormalisation scale dependence, which amount to two to three orders-of-magnitude uncertainty in the peak gravitational wave amplitude, relevant to experiments such as LISA. Alternatively, utilising dimensional reduction in a more sophisticated perturbative approach drastically reduces this scale dependence, pushing it to higher orders. Further, this approach resolves other thorny problems with daisy resummation: it is gauge invariant which is explicitly demonstrated for the Standard Model, and avoids an uncontrolled derivative expansion in the bubble nucleation rate.

    hep-phastro-ph.COgr-qchep-thJHEP(2021)·318 citations
18. 18*

    Constraints on Axion-like Particles from a Hard $X$-ray Observation of Betelgeuse

    Mengjiao Xiao🇺🇸 · Kerstin M. Perez🇺🇸 · Maurizio Giannotti🇺🇸 · Oscar Straniero🇮🇹 · Alessandro Mirizzi🇮🇹 · Brian W. Grefenstette🇺🇸 · Brandon M. Roach🇺🇸 · Melania Nynka🇺🇸

    We use the first observation of Betelgeuse in hard $X$-rays to perform a novel search for axion-like particles (ALPs). Betelgeuse is not expected to be a standard source of $X$-rays, but light ALPs produced in the stellar core could be converted back into photons in the Galactic magnetic field, producing a detectable flux that peaks in the hard $X$-ray band ($E_{\gamma }>10\mathrm{keV}$). Using a 50 ks observation of Betelgeuse by the $NuSTAR$ satellite telescope, we find no significant excess of events above the expected background. Using models of the regular Galactic magnetic field in the direction of Betelgeuse, we set a 95% C.L. upper limit on the ALP-photon coupling of $g_{a\gamma }<(0.5-1.8)\times 10^{-11}$ GeV${}^{-1}$ (depending on magnetic field model) for ALP masses $m_a<(5.5-3.5)\times 10^{-11}$ eV.

    ↳ astro-ph.HEhep-phPRL(2021)·70 citations
19. 19*

    Dichotomy of Baryons as Quantum Hall Droplets and Skyrmions In Compact-Star Matter

    Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷

    We review the recent exploration of a possible "domain-wall structure" of compressed baryonic matter in massive compact stars in terms of fractional quantum Hall droplets and skyrmions for baryons in medium. The theoretical framework is anchored on an effective nuclear effective field theory that incorporates two hidden symmetries, flavor local symmetry and scale symmetry conjectured to be dual to the gluons and quarks of QCD. It hints at a basically different, hitherto undiscovered structure of nuclear matter at low as well as high densities. Hidden "genuine dilaton (GD)" symmetry and hidden local symmetry (HLS) gauge-equivalent at low density to nonlinear sigma model capturing chiral symmetry, put together in nuclear effective field theory, are seen to play an increasingly important role in providing hadron-quark duality in baryonic matter. This strongly motivates incorporating both symmetries in formulating "first-principles" approaches to nuclear dynamics encompassing from the nuclear matter density to the highest density stable in the Universe.

    ↳ nucl-thastro-ph.HEhep-phSymmetry(2021)·28 citations
20. 20*

    DM halo morphological types of MW-like galaxies in the TNG50 simulation: Simple, Twisted, or Stretched

    Razieh Emami (Center for Astrophysics, Harvard & Smithsonian)🇺🇸 · Shy Genel🇺🇸 · Lars Hernquist🇺🇸 · Charles Alcock🇺🇸 · Sownak Bose🇺🇸 · Rainer Weinberger🇺🇸 · Mark Vogelsberger🇺🇸 · Federico Marinacci🇮🇹 · Abraham Loeb🇺🇸 · Paul Torrey🇺🇸 · John C. Forbes🇺🇸

    We present a comprehensive analysis of the shape of dark matter (DM) halos in a sample of 25 Milky Way-like galaxies in TNG50 simulation. Using an Enclosed Volume Iterative Method (EVIM), we infer an oblate-to-triaxial shape for the DM halo with the median $T\simeq 0.24$. We group DM halos in 3 different categories. Simple halos (32% of population) establish principal axes whose ordering in magnitude does not change with radius and whose orientations are almost fixed throughout the halo. Twisted halos (32% of population), experience levels of gradual rotations throughout their radial profiles. Finally, stretched halos (36% of population) demonstrate a stretching in their principal axes lengths where the ordering of different eigenvalues change with radius. Subsequently, the halo experiences a "rotation" of $\sim$90 deg where the stretching occurs. Visualizing the 3D ellipsoid of each halo, for the first time, we report signs of re-orienting ellipsoid in twisted and stretched halos. We examine the impact of baryonic physics on DM halo shape through a comparison to dark matter only (DMO) simulations. This suggests a triaxial (prolate) halo. We analyze the impact of substructure on DM halo shape in both hydro and DMO simulations and confirm that their impacts are subdominant. We study the distribution of satellites in our sample. In simple and twisted halos, the angle of satellites' angular momentum with galaxy's angular momentum grows with radius. However, stretched halos show a flat distribution of angles. Overlaying our theoretical outcome on the observational results presented in the literature establishes a fair agreement.

    ↳ astro-ph.GAastro-ph.COastro-ph.HEhep-phApJ(2021)·26 citations
21. 21*

    ${\Lambda }_b\to {\Lambda }^{\ast }(1520){\ell }^{+}{\ell }^{-}$ form factors from lattice QCD

    Stefan Meinel🇺🇸 · Gumaro Rendon🇺🇸

    We present the first lattice QCD determination of the ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ vector, axial vector, and tensor form factors that are relevant for the rare decays ${\Lambda }_b\to {\Lambda }^{\ast }(1520){\ell }^{+}{\ell }^{-}$. The lattice calculation is performed in the ${\Lambda }^{\ast }(1520)$ rest frame with nonzero ${\Lambda }_b$ momenta, and is limited to the high-$q^2$ region. An interpolating field with covariant derivatives is used to obtain good overlap with the ${\Lambda }^{\ast }(1520)$. The analysis treats the ${\Lambda }^{\ast }(1520)$ as a stable particle, which is expected to be a reasonable approximation for this narrow resonance. A domain-wall action is used for the light and strange quarks, while the $b$ quark is implemented with an anisotropic clover action with coefficients tuned to produce the correct $B_s$ kinetic mass, rest mass, and hyperfine splitting. We use three different ensembles of lattice gauge-field configurations generated by the RBC and UKQCD collaborations, and perform extrapolations of the form factors to the continuum limit and physical pion mass. We give Standard-Model predictions for the ${\Lambda }_b\to {\Lambda }^{\ast }(1520){\ell }^{+}{\ell }^{-}$ differential branching fraction and angular observables in the high-$q^2$ region.

    ↳ hep-lathep-exhep-phPRD(2021)·51 citations
22. 22*

    Measurements of branching fractions and CP-violating charge asymmetries in charmless $B$ decays reconstructed in 2019--2020 Belle~II data

    Belle II Collaboration: F. Abudinén🇮🇹 · I. Adachi🇯🇵 · R. Adak🇨🇳 · K. Adamczyk🇵🇱 · P. Ahlburg🇩🇪 · J. K. Ahn🇰🇷 · H. Aihara🇯🇵 · N. Akopov🇦🇲 · A. Aloisio🇮🇹 · F. Ameli🇮🇹 · L. Andricek🇩🇪 · N. Anh Ky🇻🇳 and 534 other authors

    We report on first measurements of branching fractions~($\mathcal{B}$) and CP-violating charge asymmetries~($\mathcal{A}$) in charmless $B$ decays at Belle~II. We use a sample of electron-positron collisions collected in 2019 and 2020 at the ${\rm Y}(4S)$ resonance and corresponding to $34.6$\,fb${}^{-1}$ of integrated luminosity. We use simulation to determine optimized event selections. The $\Delta E$ distributions of the resulting samples, restricted in $M_{\mathrm{bc}}$, are fit to determine signal yields. Signal yields are corrected for efficiencies determined from simulation and control data samples to obtain branching fractions and CP-violating asymmetries for flavour-specific channels. These are the first measurements in charmless decays reported by Belle~II. Results are compatible with known determinations and show detector performance comparable with the best Belle results offering a reliable basis to assess projections for future reach.

    ↳ hep-exhep-ph11 citations
23. 23*

    A Preliminary Determination of the Second Mellin Moment of the Pion's Distribution Amplitude Using the Heavy Quark Operator Product Expansion

    William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Santanu Mondal🇺🇸 · Robert J. Perry🇹🇼 · Yong Zhao🇺🇸

    We explore the feasibility of determining Mellin moments of the pion's light cone distribution amplitude using the heavy quark operator product expansion (HOPE) method. As the first step of a proof of principle study we pursue a determination of the second Mellin moment. We discuss our choice of kinematics which allows us to successfully extract the moment at low pion momentum. We describe the numerical simulation, and describe the data analysis, which leads us to a preliminary determination of the second Mellin moment in the continuum limit in the quenched approximation as $⟨{\xi }^2⟩=0.19(7)$ in the $\overline{\text{MS}}$ scheme at 2 GeV.

    ↳ hep-lathep-ph10 citations
24. 24*

    Collectivity in large and small systems formed in ultrarelativistic collisions

    Rajeev S Bhalerao🇮🇳

    Collective flow of the final-state hadrons observed in ultrarelativistic heavy-ion collisions or even in smaller systems formed in high-multiplicity pp and p/d/${}^3$He-nucleus collisions is one of the most important diagnostic tools to probe the initial state of the system and to shed light on the properties of the short-lived, strongly-interacting many-body state formed in these collisions. Limited, in the initial years, to the study of mainly the directed and elliptic flows -- the first two Fourier harmonics of the single-particle azimuthal distribution -- this field has evolved in recent years into a much richer area of activity. This includes not only higher Fourier harmonics and multiparticle cumulants, but also a variety of other related observables, such as the ridge seen in two-particle correlations, flow decorrelation, symmetric cumulants and event-plane correlators which measure correlations between the magnitudes or phases of the complex flows in different harmonics, coefficients that measure the nonlinear hydrodynamic response, statistical properties, such as the non-Gaussianity of the flow fluctuations, etc. We present a Tutorial Review of the modern flow picture and the various aspects of the collectivity -- an emergent phenomenon in quantum chromodynamics.

    ↳ nucl-thhep-phnucl-exEur.Phys.J.ST(2021)·19 citations
25. 25*

    Gravitational Waves and Dark Radiation from Dark Phase Transition: Connecting NANOGrav Pulsar Timing Data and Hubble Tension

    Yuichiro Nakai🇨🇳 · Motoo Suzuki🇨🇳 · Fuminobu Takahashi🇯🇵 · Masaki Yamada🇯🇵

    Recent pulsar timing data reported by the NANOGrav collaboration may indicate the existence of a stochastic gravitational wave background around $f\sim 10^{-8}$ Hz. We explore a possibility to generate such low-frequency gravitational waves from a dark sector phase transition. Assuming that the dark sector is completely decoupled from the visible sector except via the gravitational interaction, we find that some amount of dark radiation should remain until present. The NANOGrav data implies that the amount of dark radiation is close to the current upper bound, which may help mitigate the so-called Hubble tension. If the existence of dark radiation is not confirmed in the future CMB-S4 experiment, it would imply the existence of new particles feebly interacting with the standard model sector at an energy scale of O(1-100) MeV.

    ↳ astro-ph.COgr-qchep-phPLB(2021)·177 citations
26. 26*

    Vielbein with mixed dimensions and gravitational global monopole in the planar phase of superfluid ${}^3$He

    G.E. Volovik🇫🇮

    The planar phase of superfluid ${}^3$He has Dirac points in momentum space and the analog of Dirac monopole in the real space. Here we discuss the combined effect of Dirac point and Dirac monopole. It is shown that in the presence of the monopole the effective metric acting on Dirac fermions corresponds to the metric produced by the global monopole in general relativity: it is the conical metric. Another consequence is that the primary variable, which gives rise to the effective metric, is the unusual vielbein field in the form of the $4\times 5$ matrix, as distinct from the conventional $4\times 4$ matrix of the tetrad field in tetrad gravity.

    ↳ cond-mat.othergr-qchep-phhep-thPisma Zh.Eksp.Teor.Fiz.(2020)·9 citations
27. 27*

    Sound speed resonance of the stochastic gravitational wave background

    Yi-Fu Cai🇨🇳 · Chunshan Lin🇵🇱 · Bo Wang🇨🇳 · Sheng-Feng Yan🇨🇳

    We propose a novel mechanism to test time variation of the propagation speed of gravitational waves (GWs) in light of GWs astronomy. As the stochastic GWs experience the whole history of cosmic expansion, they encode potential observational evidence of such variation. We report that, one feature of a varying GWs speed is that the energy spectrum of GWs will present resonantly-enhanced peaks if the GWs speed oscillates in time at high-energy scales. Such oscillatory behaviour arises in a wide class of modified gravity theories. The amplitude of these peaks can be at reach by current and forthcoming GWs instruments, hence making the underlying theories falsifiable. This mechanism reveals that probing the variation of GWs speed can be a promising way to search for new physics beyond general relativity.

    ↳ gr-qcastro-ph.COhep-phhep-thPRL(2021)·63 citations
28. 28*

    Decays of an exotic $1^{-+}$ hybrid meson resonance in QCD

    Antoni J. Woss🇬🇧 · Jozef J. Dudek🇺🇸 · Robert G. Edwards🇺🇸 · Christopher E. Thomas🇬🇧 · David J. Wilson🇬🇧

    We present the first determination of the hadronic decays of the lightest exotic $J^{PC}=1^{-+}$ resonance in lattice QCD. Working with SU(3) flavor symmetry, where the up, down and strange quark masses approximately match the physical strange-quark mass giving $m_{\pi }\sim 700$ MeV, we compute finite-volume spectra on six lattice volumes which constrain a scattering system featuring eight coupled channels. Analytically continuing the scattering amplitudes into the complex energy plane, we find a pole singularity corresponding to a narrow resonance which shows relatively weak coupling to the open pseudoscalar--pseudoscalar, vector--pseudoscalar and vector--vector decay channels, but large couplings to at least one kinematically-closed axial-vector--pseudoscalar channel. Attempting a simple extrapolation of the couplings to physical light-quark mass suggests a broad ${\pi }_1$ resonance decaying dominantly through the $b_1\pi$ mode with much smaller decays into $f_1\pi$, $\rho \pi$, ${\eta }^{\prime }\pi$ and $\eta \pi$. A large total width is potentially in agreement with the experimental ${\pi }_1(1564)$ candidate state, observed in $\eta \pi$, ${\eta }^{\prime }\pi$, which we suggest may be heavily suppressed decay channels.

    ↳ hep-lathep-phPRD(2021)·123 citations
29. 29*

    Near-critical supernova outflows and their neutrino signatures

    Alexander Friedland (SLAC)🇺🇸 · Payel Mukhopadhyay (SLAC and Stanford U.)🇺🇸

    We demonstrate that the neutrino-driven outflows inside exploding core-collapse supernovae possess a special property of near-criticality, that is, they are on the edge of forming termination shocks. We derive a novel criterion for the formation of the shock, in terms of the fundamental parameters of the problem: the neutrino luminosity and energy as well as the properties of the protoneutron star. The criterion provides a unified description of the available numerical results and motivates future simulations. The property of near-criticality makes the neutrino signatures of the termination shocks a sensitive diagnostic of the physical conditions around the PNS several seconds into the explosion. The expected signal at DUNE is found to be statistically significant.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thPLB(2022)·16 citations
30. 30*

    Imprints of Axion Superradiance in the CMB

    Diego Blas🇬🇧 · Samuel J. Witte🇪🇸

    Light axions ($m_a\lesssim 10^{-10}$ eV) can form dense clouds around rapidly rotating astrophysical black holes via a mechanism known as rotational superradiance. The coupling between axions and photons induces a parametric resonance, arising from the stimulated decay of the axion cloud, which can rapidly convert regions of large axion number densities into an enormous flux of low-energy photons. In this work we consider the phenomenological implications of a superradiant axion cloud undergoing resonant decay. We show that the low energy photons produced from such events will be absorbed over cosmologically short distances, potentially inducing massive shockwaves that heat and ionize the IGM over Mpc scales. These shockwaves may leave observable imprints in the form of anisotropic spectral distortions or inhomogeneous features in the optical depth.

    ↳ astro-ph.COgr-qchep-phPRD(2020)·33 citations
31. 31*

    Topological Gravity as the Early Phase of Our Universe

    Prateek Agrawal🇬🇧 · Sergei Gukov🇺🇸 · Georges Obied🇺🇸 · Cumrun Vafa🇺🇸

    Motivated by string dualities we propose topological gravity as the early phase of our universe. The topological nature of this phase naturally leads to the explanation of many of the puzzles of early universe cosmology. A concrete realization of this scenario using Witten's four dimensional topological gravity is considered. This model leads to the power spectrum of CMB fluctuations which is controlled by the conformal anomaly coefficients $a,c$. In particular the strength of the fluctuation is controlled by $1/a$ and its tilt by $c{g}^2$ where $g$ is the coupling constant of topological gravity. The positivity of $c$, a consequence of unitarity, leads automatically to an IR tilt for the power spectrum. In contrast with standard inflationary models, this scenario predicts $\mathcal{O}(1)$ non-Gaussianities for four- and higher-point correlators and the absence of tensor modes in the CMB fluctuations.

    ↳ hep-thastro-ph.COhep-ph55 citations
32. 32*

    Event rates for the scattering of weakly interacting massive particles from ${}^{23}$Na and ${}^{40}$Ar

    R. Sahu · V.K.B. Kota

    Detection rates for the elastic and inelastic scattering of weakly interacting massive particles (WIMP) off ${}^{23}$Na are calculated within the framework of Deformed Shell Model (DSM) based on Hartree-Fock states. First the spectroscopic properties like energy spectra and magnetic moments are calculated and compared with experiment. Following the good agreement for these, DSM wave functions are used for obtaining elastic and inelastic spin structure functions, nuclear structure coefficients etc. for the WIMP-${}^{23}$Na scattering. Then, the event rates are also calculated with a given set of supersymmetric parameters. In the same manner, using DSM wavefunctions, nuclear structure coefficients and event rates for elastic scattering of WIMP from ${}^{40}$Ar are also obtained. These results for event rates and also for annual modulation will be useful for the upcoming and future WIMP detection experiments involving detectors with ${}^{23}$Na and ${}^{40}$Ar.

    ↳ nucl-thhep-phParticles(2021)·5 citations
33. 33*

    Gravitational Collider Physics via Pulsar-Black Hole Binaries

    Qianhang Ding🇨🇳 · Xi Tong🇨🇳 · Yi Wang🇨🇳

    We propose to use pulsar-black hole binaries as a probe of gravitational collider physics. Induced by the gravitation of the pulsar, the atomic transitions of the boson cloud around the black hole back-react on the orbital motion. This leads to the deviation of binary period decrease from that predicted by general relativity, which can be directly probed by the Rømer delay of pulsar time-of-arrivals. The sensitivity and accuracy of this approach is estimated for two typical atomic transitions. It is shown that once the transitions happen within the observable window, the pulsar-timing accuracy is almost always sufficient to capture the resonance phenomenon.

    ↳ astro-ph.HEgr-qchep-phhep-thApJ(2021)·36 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.