Fri·Jan 6, 2023Friday·January 6, 2023

1. 01*

   Renormalon-chain contributions to two-point correlators of nonlocal quark currents

   S. V. Mikhailov🇷🇺 · N. Volchanskiy🇷🇺

   We calculate, within massless QCD, a two-point correlator of nonlocal (composite) vector quark currents with arbitrary-length chains of the simplest fermion loops being inserted into gluon lines. Within the large $n_f$ (or large ${\beta }_0$) approximation, the correlator defines a perturbative contribution to the leading-twist distribution amplitudes for light mesons. Our results are consistent with a number of special cases in the literature. We consider functionals of the correlator, which are important for the phenomenology, and their properties as function series.

   hep-phPhys.Part.Nucl.Lett.·4 citations
2. 02*

   Search for an Ultraviolet Zero in the Seven-Loop Beta Function of the $\lambda {\varphi }_4^4$ Theory

   Robert Shrock🇺🇸

   We investigate whether the seven-loop beta function of the $\lambda {\varphi }_4^4$ theory exhibits evidence for an ultraviolet zero. In addition to a direct analysis of the beta function, we calculate and study Padé approximants and discuss effects of scheme transformations on the results. Confirming and extending our earlier studies of the five-loop and six-loop beta functions, we find that in the range of $\lambda$ where the perturbative calculation of the seven-loop beta function is reliable, the theory does not exhibit evidence for an ultraviolet zero.

   hep-phhep-thPRD(2023)·4 citations
3. 03*

   Open Charm Mesons and Charmonium states in Magnetized Strange Hadronic Medium at Finite Temperature

   Amal Jahan C.S. · Amruta Mishra🇮🇳

   We investigate the masses of the pseudoscalar ($D$($D^0$, $D^{+}$), $\bar{D}$($\overline{D^0}$, $D^{-}$) and vector open charm mesons ($D^{\ast }$($D^{\ast 0}$, $D^{\ast +}$), ${\bar{D}}^{\ast }$(${\bar{D}}^{\ast 0}$, $D^{\ast -}$) as well as the pseudoscalar (${\eta }_c(1S)$, ${\eta }_c(2S)$) and the vector charmonium states ($J/\psi$, $\psi (2S)$, $\psi (1D)$) in the asymmetric hot strange hadronic medium in the presence of strong magnetic fields. In the magnetized medium, the mass modification of open charm mesons due to their interactions with baryons and the scalar fields ($\sigma$, $\zeta$, and $\delta$) are investigated in a chiral effective model. Moreover, the charged pseudoscalar meson ($D^{\pm }$), as well as the longitudinal component of charged vector meson ($D^{\ast \pm \parallel }$), experience additional positive mass modifications in the magnetic field due to Landau quantization. The effect of the modification of gluon condensates simulated by the medium change of dilaton field $\chi$ on the masses of the charmonia is also calculated in the chiral effective model. At high temperatures, the magnetically induced modifications of scalar fields significantly reduce the in-medium masses of mesons. The effects of magnetically induced spin mixing between the pseudoscalar and the vector mesons are incorporated in our study. The spin mixing result in a positive mass shift for the longitudinal component of the vector mesons and a negative mass shift for the pseudoscalar mesons in the presence of the magnetic field. From the obtained in-medium mass shifts of charmonia and open charm mesons, we have also calculated the partial decay widths of $\psi (1D)$ to $D\bar{D}$, using a light quark pair creation model, namely the ${}^3{P}_0$ model. Spin mixing and strangeness fraction enhance the partial decay width at small magnetic fields.

   hep-phIJMPE(2023)·0 citations
4. 04*

   Strong decays of $P_{\psi }^N(4312{)}^{+}$ to $J/\psi ({\eta }_c)p$ and ${\bar{D}}^{(\ast )}{\Lambda }_c$ within the Bethe-Salpeter framework

   Qiang Li🇨🇳 · Chao-Hsi Chang🇨🇳 · Tianhong Wang🇨🇳 · Guo-Li Wang🇨🇳

   Based on the effective Lagrangian in the heavy quark limit, we calculate the one-boson-exchange interaction kernel of $P_{\psi }^N(4312{)}^{+}$ as the $\bar{D}{\Sigma }_c$ molecular state in isospin-$\frac{1}{2}$. We present the Bethe-Salpeter equation and wave function for the constituent particles to be a (pseudo)scalar meson and a $\frac{1}{2}$ baryon. By solving the Bethe-Salpeter equation, we obtain $P_{\psi }^N(4312{)}^{+}$ as the $\bar{D}{\Sigma }_c$ molecular state with $J^P=(\frac{1}{2}{)}^{-}$. Combining the effective Lagrangian and the obtained BS wave function, the partial decay widths of $P_{\psi }^N(4312{)}^{+}$ to $J/\psi p$, ${\eta }_{c}p$, ${\bar{D}}^{\ast 0}{\Lambda }_c^{+}$ and ${\bar{D}}^0{\Lambda }_c^{+}$ are calculated to be $0.17$, $0.085$, $8.8$, and $0.026$ MeV, respectively, which are roughly consistent with the LHCb experimental measurements and some other theoretical researches. The obtain results indicate the fraction of ${\bar{D}}^{\ast 0}{\Lambda }_c^{+}$ channel amounts to $\sim 90\%$ of $P_{\psi }^N(4312{)}^{+}$, and is a highly promising channel to be discovered in the near future experiments. Our results favor the interpretation of $P_{\psi }^N(4312{)}^{+}$ as the $\bar{D}{\Sigma }_c$ molecular state with $J^P=(\frac{1}{2}{)}^{-}$ and isospin $I=\frac{1}{2}$.

   hep-phhep-exJHEP(2023)·13 citations
5. 05*

   Resolving $R_D$ and $R_{D^{\ast }}$ Anomalies in Adjoint SU(5)

   A. Ismael🇪🇬 · S. Khalil🇪🇬

   We investigate the $R_D$ and $R_{D^{\ast }}$ anomalies in the context of non-minimal $SU(5)$, where Higgs sector is extended by adjoint 45-dimensional multiplet. One of the light spectrum of this model could be the scalar triplet leptoquark that is contained in this multiplet. We demonstrate that this particular scalar leptoquark mediation of the transition $b\to c\tau \nu$ is capable of simultaneously accounting for both $R_D$ and $R_{D^{\ast }}$ anomalies. We further emphasize that another Yukawa coupling controls its contribution to $b\to s{\ell }^{+}{\ell }^{-}$, ensuring that $R_K$ and $R_{K^{\ast }}$ remain consistent with the standard model predictions.

   hep-phJHEP(2023)·3 citations
6. 06*

   Light scalar explanation for 18 TeV GRB 221009A

   Shyam Balaji🇫🇷 · Maura E. Ramirez-Quezada🇯🇵 · Joseph Silk🇫🇷 · Yongchao Zhang🇨🇳

   Recent astrophysical transient Swift J1913.1+1946 may be associated with the $\gamma$-ray burst GRB 221009A. The redshift of this event is $z\simeq 0.151$. Very high-energy $\gamma$-rays (up to 18 TeV) followed the transient and were observed by LHAASO, additionally Carpet-2 detected a photon-like air shower of 251 TeV. Photons of such high energy are expected to readily annihilate with the diffuse extragalactic background light (EBL) before reaching Earth. If the $\gamma$-ray identification and redshift measurements are correct, new physics could be necessary to explain these measurements. This letter provides the first CP-even scalar explanation of the most energetic 18 TeV event reported by LHAASO. In this minimal scenario, the light scalar singlet $S$ mixes with the Standard Model (SM) Higgs boson $h$. The highly boosted $S$ particles are produced in the GRB and then undergo the radiative decay di-photon $S\to \gamma \gamma$ while propagating to Earth. The resulting photons may thus be produced at a remote region without being nullified by the EBL. Hence, the usual exponential reduction of $\gamma$-rays is lifted due to an attenuation that is inverse in the optical depth, which becomes much larger due to the scalar carriers.

   hep-phastro-ph.HEPRD(2023)·17 citations
7. 07*

   On (Scalar QED) Gravitational Positivity Bounds

   Yuta Hamada🇯🇵 · Rinto Kuramochi🇯🇵 · Gregory J. Loges🇯🇵 · Sota Nakajima🇯🇵

   We study positivity bounds in the presence of gravity. We first review the gravitational positivity bound at the tree-level, where it is known that a certain amount of negativity is allowed for the coefficients of higher-derivative operators. The size of these potentially negative contributions is estimated for several tree-level, Reggeized gravitational amplitudes which are unitary at high energies and feature the t-channel pole characteristic of graviton exchange. We also argue for the form of the one-loop Regge amplitude assuming that the branch cut structure associated with the exchange of the graviton and higher-spin particles is reflected. We demonstrate how the one-loop Regge amplitude appears by summing over Feynman diagrams. For our one-loop amplitude proposal, the positivity bounds generically receive a finite contribution from the Regge tower and do not lead to a parametrically small bound on the cut-off scale of the low-energy EFT, consistent with recent studies based on sum rules of the amplitude.

   ↳ hep-thhep-phJHEP(2023)·23 citations
8. 08*

   $0^{+}$ to $2^{+}$ neutrinoless double-$\beta$ decay of ${}^{76}$Ge, ${}^{82}$Se, ${}^{130}$Te and ${}^{136}$Xe in the microscopic interacting boson model}

   J. Ferretti🇫🇮 · R. Magana Vsevolodovna🇮🇹 · J. Kotila🇫🇮 · E. Santopinto🇮🇹

   Here, we study the neutrinoless double-$\beta$ ($0\nu \beta \beta$) decay between the ground state and the first $2^{+}$ state of ${}^{76}\text{mbox}Ge\to {}^{76}\text{mbox}Se$, ${}^{82}\text{mbox}Se\to {}^{82}\text{mbox}Kr$, ${}^{130}\text{mbox}Te\to {}^{130}\text{mbox}Xe$ and ${}^{136}\text{mbox}Xe\to {}^{136}\text{mbox}Ba$ systems. The relevant nuclear matrix elements (NMEs) involved in the process are calculated within the formalism of the microscopic interacting boson model (IBM-2). The IBM-2 has been widely used to obtain predictions for nuclear observables, such as the spectrum, but also to explore the possible emergence of beyond-the-Standard Model effects in the weak interactions of nuclei. Our calculations are carried out by considering the exchange of a Majorana neutrino between two nucleons ($2N$-mechanism). In addition to NMEs, we calculate the associated leptonic phase-space factors (PSFs) using electron radial wave functions, which are obtained by solving numerically the Dirac equation of a screened Coulomb potential that takes into account finite nuclear size. By combining our IBM-2 results for the NMEs with those for the PSFs along with experimental half-life limits, we can set limits on the $⟨\lambda ⟩$ and $⟨\eta ⟩$ couplings of left-right (L-R) models.

   ↳ nucl-thhep-ph2 citations
9. 09*

   A Simple Derivation of the Gertsenshtein Effect

   Andrea Palessandro🇺🇸 · Tony Rothman🇺🇸

   As shown by Gertsenshtein in 1961, an external magnetic field can catalyze the mixing of graviton and photon states in a manner analogous to neutrino-flavor oscillations. We first present a straightforward derivation of the mechanism by a method based on unpublished notes of Freeman Dyson. We next extend his method to include boundary conditions and retrieve the results of Boccaletti et al. from 1970. We point out that, although the coupling between the graviton and photon states is extremely weak, the large magnetic fields around neutron stars $\sim 10^{14}$ G make the Gertsenshtein effect a plausible source of gravitons. We also point out that axion-photon mixing, a subject of active current research, is essentially the same process as the Gertsenshtein effect, and so the general mechanism may be of broad astrophysical and cosmological interest.

   ↳ gr-qcastro-ph.HEhep-phphysics.class-phPhys.Dark Univ.(2023)·30 citations
10. 10*

    Topology and emergent symmetries in dense compact star matter

    Yong-Liang Ma🇨🇳 · Wen-Cong Yang🇨🇳

    It has been found that the topology effect and the possible emergent scale and hidden local flavor symmetries at high density reveal a novel structure of the compact star matter. The $N_f\ge 2$ baryons can be described by the skyrmion in the large $N_c$ limit and there is a robust topology change in the skyrmion matter approach to dense nuclear matter. The hidden scale and local flavor symmetries which are sources introducing the lightest scalar meson -- dilaton -- and lowest lying vector mesons into to nonlinear chiral effective theory are seen to play important roles in understanding the nuclear force. We review in this paper the generalized nuclear effective theory (G$n$EFT), which applicable to nuclear matter from low density to the compact star density, constructed with the robust conclusion from the topology approach to dense matter and emergent scale and hidden local flavor symmetries. The topology change at density larger than two times saturation density $n_0$ encoded in the parameters of the effective field theory is interpreted as the hadron-quark continuity in the sense of Cheshire Cat Principle. A novel feature predicted in this theory that has not been found before is the precocious appearance of the conformal sound velocity in the cores of massive stars, although the trace of the energy-momentum tensor of the system is not zero. That is, in contrast to the usual picture, the cores of massive stars are composed of quasiparticles of fractional baryon charges, neither baryons nor deconfined quarks. Hidden scale and local flavor symmetries emerge and give rise a resolution of the longstanding $g_A$ quench problem in nuclei transition. To illustrate the rationality of the GnEFT, we finally confront the generalized effective field theory to the global properties of neutron star and the data from gravitational wave detections.

    ↳ nucl-thhep-phSymmetry(2023)·14 citations
11. 11*

    Reduced nuclear helicity amplitudes for deuteron electrodisintegration and other processes

    J. Flores🇺🇸 · S.S. Chabysheva🇺🇸 · J.R. Hiller🇺🇸

    We extend the original idea of reduced nuclear amplitudes to capture individual helicity amplitudes and discuss various applications to exclusive processes involving the deuteron. Specifically, we consider deuteron form factors, structure functions, tensor polarization observables, photodisintegration, and electrodisintegration. The basic premise is that nuclear processes at high momentum transfer can be approximated by tree graphs for point-like nucleons supplemented by empirical form factors for each nucleon. The latter represent the internal structure of the nucleon, and incorporate nonperturbative physics, which can allow for early onset of scaling behavior. The nucleon form factors are evaluated at the net momentum transfer experienced by the given nucleon, with use of $G_E$ for a no-flip contribution and $G_M$ for a helicity-flip contribution. Results are compared with data where available. The deuteron photodisintegration asymmetry $\Sigma$ is obtained with a value of $\Sigma (90^{\circ })\simeq -0.06$, which is much closer to experiment than the value of -1 originally expected. The method also provides an estimate of the momentum transfer values required for scaling onset. We find that the deuteron structure function $B$ is a good place to look, above momentum transfers of 10 GeV${}^2$.

    ↳ nucl-thhep-phPRC(2023)·1 citation

* 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.