Mon·Aug 16, 2021Monday·August 16, 2021

1. 01*

   Dark Sector Production via Proton Bremsstrahlung

   S. Foroughi-Abari🇨🇦 · A. Ritz🇨🇦

   Experiments using proton beams at high luminosity colliders and fixed target facilities provide impressive sensitivity to new light weakly coupled degrees of freedom. With these experiments in mind, we revisit the production of dark vectors and scalars via proton bremsstrahlung, making use of a model that describes the underlying nucleon scattering cross-section in the forward direction due to pomeron exchange. We compare the resulting distributions and rates with those obtained via variants of the Fermi-Weizsacker-Williams approximation, and provide production rate distributions for a range of beam energies, including those relevant for the proposed Forward Physics Facility at the High Luminosity-LHC.

   hep-phPRD(2022)·59 citations
2. 02*

   Anomaly-free Abelian gauge symmetries with Dirac seesaws

   Nicolás Bernal🇨🇴 · Diego Restrepo🇨🇴

   We perform a systematic analysis of Standard Model extensions with an additional anomaly-free gauge $U(1)$ symmetry, to generate tree-level Dirac neutrino masses. An anomaly-free symmetry demands nontrivial conditions on the charges of the unavoidable new states. An intensive scan was performed, looking for solutions generating neutrino masses by the type-I and type-II tree-level Dirac seesaw mechanism, via operators with dimension 5 and 6, that correspond to active or dark symmetries. Special attention was paid to the cases featuring no extra massless chiral fermions or multicomponent dark matter with unconditional stability.

   hep-phEPJC(2021)·12 citations
3. 03*

   Pole analysis on the doubly charmed meson in $D^0{D}^0{\pi }^{+}$ mass spectrum

   Ling-Yun Dai🇨🇳 · Xiang Sun🇨🇳 · Xian-Wei Kang🇨🇳 · A. P. Szczepaniak🇺🇸 · Jie-Sheng Yu🇨🇳

   In this paper we study the scattering amplitudes of $D^0{D}^0{\pi }^{+}$-$D^{\ast +}{D}^0$ coupled channels based on $K$-matrix within the Chew-Mandelstam formalism. The $D^0{D}^0{\pi }^{+}$ invariant mass spectrum of LHCb is fitted and the pole parameters of the $T_{cc}^{+}$ are extracted. The analysis of pole behavior suggests that the $T_{cc}^{+}$ may originate from a $D^{\ast +}{D}^0$ virtual state and is formed as a result of an interplay between an attractive interaction between $D^0$ and $D^{\ast +}$ and coupling to $D^0{D}^0{\pi }^{+}$ channel.

   hep-phnucl-thPRD(2022)·36 citations
4. 04*

   $R^2$/Higgs inflation and the hierarchy problem

   Pedro G. Ferreira🇬🇧 · Christopher T. Hill🇺🇸 · Johannes Noller🇬🇧 · Graham G. Ross🇬🇧

   We analyse Starobinsky inflation in the presence of the Brout Englert Higgs (BEH) boson with a non-minimal coupling to the Ricci scalar, $R$. The latter induces a coupling of the massive scaleron associated with the $R^2$ term to the BEH boson and this leads to a radiative correction to the BEH mass that must be fine tuned to keep the scalar light. For the case of $R^2$ driven inflation this requires a high level of fine tuning of order 1 part in $10^8$; for the case of Higgs inflation it is very much greater. We consider a scale invariant extension of the $R^2$/Higgs model and find that for $R^2$ driven inflation but not for Higgs inflation the required fine tuning is significantly reduced to one part in $10^{3-4}$. We consider the vacuum stability of the fine tuned model and its reheating and dilaton abundance after inflation. We also discuss possible gravitational wave signals associated with the model and the constraint on the mass of scalar or fermion dark matter candidates if they are produced by the gravitational couplings of the scalaron.

   hep-phastro-ph.CO11 citations
5. 05*

   Angular Distributions for Multi-body Semileptonic Charmed Baryon Decays

   Fei Huang🇨🇳 · Qi-An Zhang🇨🇳

   We perform an analysis of angular distributions in semileptonic decays of charmed baryons $B_1^{(\prime )}\to B_2^{(\prime )}(\to B_3^{(\prime )}{B}_4^{(\prime )}){\ell }^{+}{\nu }_{\ell }$, where the $B_1=({\Lambda }_c^{+},{\Xi }_c^{(0,+)})$ are the SU(3)-antitriplet baryons and $B_1^{\prime }={\Omega }_c^{-}$ is an SU(3) sextet. We will firstly derive analytic expressions for angular distributions using helicity amplitude technique. Based on the lattice QCD results for ${\Lambda }_c^{+}\to \Lambda$ and ${\Xi }_c^0\to {\Xi }^{-}$ form factors and model calculation of the ${\Omega }_c^0\to {\Omega }^{-}$ transition, we predict branching fractions: $\mathcal{B}({\Lambda }_c^{+}\to p{\pi }^{-}{e}^{+}{\nu }_e)=2.48(15)\%$, $\mathcal{B}({\Lambda }_c^{+}\to p{\pi }^{-}{\mu }^{+}{\nu }_{\mu })=2.50(14)\%$, $\mathcal{B}({\Xi }_c\to \Lambda {\pi }^{-}{e}^{+}{\nu }_e)=2.40(30)\%$, $\mathcal{B}({\Xi }_c\to \Lambda {\pi }^{-}{\mu }^{+}{\nu }_{\nu })=2.41(30)\%$, $\mathcal{B}({\Omega }_c\to \Lambda K^{-}{e}^{+}{\nu }_e)=0.362(14)\%$, $\mathcal{B}({\Omega }_c\to \Lambda K^{-}{\mu }^{+}{\nu }_{\nu })=0.350(14)\%$. Besides, we also predict the $q^2$-dependence and angular distributions of these processes, in particular the coefficients for the $\cos n{\theta }_{\ell }$ ($\cos n{\theta }_h$, $\cos n\varphi$) $(n=0,1,2,\cdots )$ terms. This work can provide a theoretical basis for the ongoing experiments at BESIII, LHCb and BELLE-II.

   hep-phEPJC(2022)·21 citations
6. 06*

   Semi-leptonic three-body proton decay modes from light-cone sum rules

   Ulrich Haisch🇩🇪 · Amando Hala🇩🇪

   Using light-cone sum rule techniques, we estimate the form factors which parametrise the hadronic matrix elements that are relevant for semi-leptonic three-body proton decays. The obtained form factors allow us to determine the differential rate for the decay of a proton ($p$) into a positron ($e^{+}$), a neutral pion (${\pi }^0$) and a graviton ($G$), which is the leading proton decay channel in the effective theory of gravitons and Standard Model particles (GRSMEFT). The sensitivity of existing and next-generation neutrino experiments in detecting the $p\to e^{+}{\pi }^{0}G$ signature is studied and the phenomenological implications of our computations for constraints on the effective mass scale that suppresses the relevant baryon-number violating GRSMEFT operator are discussed.

   hep-phhep-exJHEP(2021)·4 citations
7. 07*

   Study of light tetraquark spectroscopy

   Zheng Zhao🇹🇭 · Kai Xu🇹🇭 · Attaphon Kaewsnod🇹🇭 · Xuyang Liu🇹🇭 · Ayut Limphirat🇹🇭 · Yupeng Yan🇹🇭

   We calculate the masses of the $qq\bar{q}\bar{q}$ tetraquark ground state and first radial excited state in a constituent quark model where the Cornell-like potential and one-gluon exchange spin-spin coupling are employed. The three coupling parameters for the Cornell-like potential and one-gluon exchange spin-spin coupling are proposed mass-dependent in accordance with Lattice QCD data, and all model parameters are predetermined by studying light, charmed and bottom mesons. The theoretical predictions for light tetraquarks are compared with the observed exotic meson states in the light-unflavored meson sector, and tentative assignments are suggested. The work suggests that the $f_0(1500)$ and $f_0(1710)$ might be ground light tetraquark states with $J=0$.

   hep-phPRD(2022)·11 citations
8. 08*

   Impact of systematic and amplitude model correlations within and between systems of combined input: A case study with ${\varphi }_2$ ($\alpha$)

   J. Dalseno🇪🇸

   The pursuit of experimental precision in the $CP$-violating weak phase ${\varphi }_2$ ($\alpha$) is not without its challenges, in part due to the need to combine multiple physical observables from various related decay channels, and therein lies a fundamental issue. Similarities in analysis procedures give rise to systematic correlations between the measured inputs constraining ${\varphi }_2$ that must be taken into account to avoid bias. Specifically, in the case of the irreducible model uncertainty accompanying analyses involving the $\rho$ meson, it is demonstrated that ignoring correlations derived from its pole parameters, or indeed even treating correlations individually contained within each decay channel, can ultimately lead to a bias in ${\varphi }_2$ of $\mathcal{O}(1^{\circ })$. Correct treatment on the other hand, markedly reduces wandering of its central value as a function of the model uncertainty strength with the added dividend of a further improved overall uncertainty. Bias in the combination of $B^0\to (\rho \pi {)}^0$ and $B\to \rho \rho$ is also seen to depend on the statistical strength of the former in relation to that of the model uncertainty in the latter. This work can inspire other studies into the points at which systematic correlations beyond those determined in single measurements matter in combinations leading to other $CP$-violating weak phases such as ${\varphi }_1$ ($\beta$), ${\varphi }_3$ ($\gamma$) and ${\varphi }_s$.

   hep-phJHEP(2021)·3 citations
9. 09*

   Misalignment vs Topology in Axion-Like Models

   Aidan Chaumet🇩🇪 · Guy D. Moore🇩🇪

   Cosmological axions, an important dark matter candidate, are generated when a scalar field with a spontaneously broken O(2) invariance develops an explicitly O(2)-breaking tilt cosmologically, leading to coherent production of long-wavelength modes which could be dark matter. It appears that the production efficiency of this mechanism is low, despite possible production from topological structures. To understand this better, we examine production in O(N) generalizations. In particular we highlight the importance of how fast the explicit O(N)-breaking potential turns on.

   hep-ph4 citations
10. 10*

    Mass spectra and decays of open-heavy tetraquark states

    Tao Guo🇨🇳 · Jianing Li🇨🇳 · Jiaxing Zhao🇨🇳 · Lianyi He🇨🇳

    Open-heavy tetraquark states, especially those contain four different quarks have drawn much attention in both theoretical and experimental fields. In the framework of the improved chromomagnetic interaction (ICMI) model, we complete a systematic study on the mass spectra and possible strong decay channels of the $S$-wave open-heavy tetraquark states, $qq\bar{q}\bar{Q}$ ($q=u,d,s$ and $Q=c,b$), with different quantum number $J^P=0^{+}$, $1^{+}$, and $2^{+}$. The parameters in the ICMI model are extracted from the conventional hadron spectra and used directly to predict the mass of tetraquark states. Several compact bound states and narrow resonances are found in both charm-strange and bottom-strange tetraquark sectors, most of them as a product of the strong coupling between the different channels. Our results show the recently discovered four different flavors tetraquark candidates $X_0(2900)$ is probably compact $ud\bar{s}\bar{c}$ state with quantum number $J^P=0^{+}$. The predictions about $X_0(2900)$ and its partners are expected to be better checked with other theories and future experiments.

    hep-phnucl-thPRD(2022)·33 citations
11. 11*

    Self-resonant Dark Matter

    Seong-Sik Kim🇰🇷 · Hyun Min Lee🇰🇷 · Bin Zhu🇨🇳

    We present a novel mechanism for Sommerfeld enhancement for dark matter interactions without the need for light mediators. Considering a model for two-component dark matter with a triple coupling, we find that one of dark matter particles leads to an $u$-channel resonance in dark matter elastic scattering. From the sum of the $u$-channel ladder diagrams, we obtain a Bethe-Salpeter equation with a delay term and identify the Sommerfeld factor from the elastic scattering of two dark matter components for the first time. We discuss the implications of our results for enhancing dark matter self-scattering and annihilation.

    hep-phastro-ph.COastro-ph.GAhep-thJHEP(2021)·7 citations
12. 12*

    Dijet impact factor in DIS at next-to-leading order in the Color Glass Condensate

    Paul Caucal🇺🇸 · Farid Salazar🇺🇸 · Raju Venugopalan🇺🇸

    We compute the next-to-leading order impact factor for inclusive dijet production in deeply inelastic electron-nucleus scattering at small $x_{\mathrm{Bj}}$. Our computation, performed in the framework of the Color Glass Condensate effective field theory, includes all real and virtual contributions in the gluon shock wave background of all-twist lightlike Wilson line correlators. We demonstrate explicitly that the rapidity evolution of these correlators, to leading logarithmic accuracy, is described by the JIMWLK Hamiltonian. When combined with the next-to-leading order JIMWLK Hamiltonian, our results for the impact factor improve the accuracy of the inclusive dijet cross section to $\mathcal{O}({\alpha }_s^2\ln (x_f/x_{\mathrm{Bj}}))$, where $x_f$ is a rapidity factorization scale. These results are an essential ingredient in assessing the discovery potential of inclusive dijets to uncover the physics of gluon saturation at the Electron-Ion Collider.

    hep-phhep-thnucl-thJHEP(2021)·106 citations
13. 13*

    Statistics of Thawing K-essence Dark Energy Models

    Zhiqi Huang🇨🇳

    K-essence is a minimally-coupled scalar field whose Lagrangian density $\mathcal{L}$ is a function of the field value $\varphi$ and the kinetic energy $X=\frac{1}{2}{\partial }_{\mu }\varphi {\partial }^{\mu }\varphi$. In the thawing scenario, the scalar field is frozen by the large Hubble friction in the early universe, and therefore initial conditions are specified. We construct thawing k-essence models by generating Taylor expansion coefficients of $\mathcal{L}(\varphi ,X)$ from random matrices. From the ensemble of randomly generated thawing k-essence models, we select dark energy candidates by assuming negative pressure and non-growth of sub-horizon inhomogeneities. For each candidate model the dark energy equation of state function is fit to the Chevallier-Polarski-Linder parameterization $w(a)\approx w_0+w_a(1-a)$, where $a$ is the scale factor. The thawing k-essence dark models distribute very non-uniformly in the $(w_0,w_a)$ space. About 90\% models cluster in a narrow band in the proximity of a slow-roll line $w_a\approx -1.42{\left(\frac{{\Omega }_m}{0.3}\right)}^{0.64}(1+w_0)$, where ${\Omega }_m$ is the present matter density fraction. This work is a proof of concept that for a certain class of models very non-uniform theoretical prior on $(w_0,w_a)$ can be obtained to improve the statistics of model selection.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2021)·6 citations
14. 14*

    Dark energy interactions near the galactic centre

    David Benisty🇬🇧 · Anne-Christine Davis🇬🇧

    We investigate scalar-tensor theories, motivated by dark energy models, in the strong gravity regime around the black hole at the centre of our galaxy. In such theories general relativity is modified since the scalar field couples to matter. We consider the most general conformal and disformal couplings of the scalar field to matter to study the orbital behavior of the nearby stars around the galactic star center $Sgr{A}^{\ast }$. Markov Chain Monte Carlo (MCMC) simulation yields a bound on the parameters of the couplings of the scalar field to matter. Using Bayesian Analysis yields the first constraints on such theories in the strong gravity regime.

    ↳ astro-ph.COastro-ph.SRgr-qchep-phPRD(2022)·48 citations
15. 15*

    Combined sensitivity of JUNO and KM3NeT/ORCA to the neutrino mass ordering

    KM3NeT Collaboration: S. Aiello · A. Albert · M. Alshamsi · S. Alves Garre · Z. Aly · A. Ambrosone · F. Ameli · M. Andre · G. Androulakis · M. Anghinolfi · M. Anguita · M. Ardid and 263 other authors

    This article presents the potential of a combined analysis of the JUNO and KM3NeT/ORCA experiments to determine the neutrino mass ordering. This combination is particularly interesting as it significantly boosts the potential of either detector, beyond simply adding their neutrino mass ordering sensitivities, by removing a degeneracy in the determination of $\Delta m_{31}^2$ between the two experiments when assuming the wrong ordering. The study is based on the latest projected performances for JUNO, and on simulation tools using a full Monte Carlo approach to the KM3NeT/ORCA response with a careful assessment of its energy systematics. From this analysis, a $5\sigma$ determination of the neutrino mass ordering is expected after 6 years of joint data taking for any value of the oscillation parameters. This sensitivity would be achieved after only 2 years of joint data taking assuming the current global best-fit values for those parameters for normal ordering.

    ↳ hep-exhep-phJHEP(2022)·23 citations
16. 16*

    Newton, entanglement, and the graviton

    Daniel Carney🇺🇸

    Many experiments have recently been proposed to test whether non-relativistic gravitational interactions can generate entanglement. In this note, I consider the extent to which these experiments can test if the graviton exists. Assuming unitarity and Lorentz invariance of the $S$-matrix, I demonstrate that this "Newtonian entanglement" requires the existence of massless bosons, universally coupled to mass, in the Hilbert space of low-energy scattering states. These bosons could be the usual spin-2 gravitons, but in principle there are other possibilities like spin-0 scalar gravitons. I suggest a concept for a more refined experiment to rule these out. The special role of $d=3+1$ spacetime dimensions and the possibility that unitarity is violated by gravity are highlighted.

    ↳ quant-phgr-qchep-phhep-thPRD(2022)·102 citations
17. 17*

    The exact SL(K+3,C) symmetry of string theory

    Sheng-Hong Lai🇹🇼 · Jen-Chi Lee🇹🇼 · Yi Yang🇹🇼

    By using on-shell recursion relation of string scattering amplitudes (SSA), we show that all n-point SSA of the open bosonic string theory can be expressed in terms of the Lauricella functions. This result extends the previous exact SL(K+3,C) symmetry of the 4-point Lauricella SSA (LSSA) of three tachyons and one arbitrary string states to the whole tree-level open bosonic string theory. Moreover, we present three applications of the SL(K+3,C) symmetry on the SSA. They are the solvability of all SSA in terms of one amplitude, the existence of iteration relations among residues of a given SSA so as to soften its hard scattering behavior and finally the re-derivation of infinite linear relations among hard SSA [12].

    ↳ hep-thhep-phPLB(2022)·5 citations
18. 18*

    Natural Selection Rules: New Positivity Bounds for Massive Spinning Particles

    Joe Davighi🇬🇧 · Scott Melville🇬🇧 · Tevong You🇨🇭

    We derive new effective field theory (EFT) positivity bounds on the elastic $2\to 2$ scattering amplitudes of massive spinning particles from the standard UV properties of unitarity, causality, locality and Lorentz invariance. By bounding the $t$ derivatives of the amplitude (which can be represented as angular momentum matrix elements) in terms of the total ingoing helicity, we derive stronger unitarity bounds on the $s$- and $u$-channel branch cuts which determine the dispersion relation. In contrast to previous positivity bounds, which relate the $t$-derivative to the forward-limit EFT amplitude with no $t$ derivatives, our bounds establish that the $t$-derivative alone must be strictly positive for sufficiently large helicities. Consequently, they provide stronger constraints beyond the forward limit and can be used to constrain dimension-6 interactions with a milder assumption about the high-energy growth of the UV amplitude.

    ↳ hep-thhep-phJHEP(2022)·67 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.