Tue·Jan 19, 2021Tuesday·January 19, 2021

1. 01*

   Cosmological chirality and magnetic fields from parity violating particle decays

   Tanmay Vachaspati (ASU)🇺🇸 · Alexander Vilenkin (Tufts)🇺🇸

   We estimate the chirality of the cosmological medium due to parity violating decays of standard model particles, focusing on the example of tau leptons. The non-trivial chirality is however too small to make a significant contribution to the cosmological magnetic field via the chiral-magnetic effect.

   hep-phastro-ph.COhep-thPRD(2021)·3 citations
2. 02*

   Analytical study on the Applicability of Ultra Generalized Exponential Hyperbolic Potential to Predict the Mass Spectra of the Heavy Mesons

   E. P. Inyang · E. P. Inyang · J.E.Ntibi · E. E. Ibekwe · E. S. William

   We solved the Klein-Gordon equation analytically using the Nikiforov-Uvarov method to obtain the energy eigenvalues and corresponding wavefunction in terms of Laguerre polynomials with the ultra generalized exponential hyperbolic potential. The present results are applied for calculating the mass spectra of heavy mesons such as charmonium (cc) and bottomonium (cc) for different quantum states. The present potential provides excellent results in comparison with experimental data with a maximum error of and work of other researchers.

   hep-phmath-phmath.MPquant-ph1 citation
3. 03*

   Testing CPT violation, entanglement and gravitational interactions in particle mixing with trapped ions

   Antonio Capolupo🇮🇹 · Salvatore Marco Giampaolo🇭🇷 · Aniello Quaranta🇮🇹

   By analyzing the analogies between the effective system of $N$ spins described by the Ising Hamiltonian and the phenomenon of the self--gravity in mixed particle systems, we show that cooled ions held in a segmented ion trap and exposed to a magnetic field gradient can simulate the proposed mechanism of mutual interaction in mixed neutrino system. We show that with trapped ions one can reproduce the expected corrections to the flavor transitions and the $CPT$ violation induced by gravity on flavor fields, which may have played an important role in the early stages of the universe. The results presented are experimentally testable. They indicate that ions confined in microtraps can represent a new tool to test fundamental phenomena of nature.

   hep-phEPJC(2021)·8 citations
4. 04*

   Self-interacting Inelastic Dark Matter in the light of XENON1T excess

   Manoranjan Dutta (1)🇮🇳 · Satyabrata Mahapatra (1)🇮🇳 · Debasish Borah (2)🇮🇳 · Narendra Sahu (1) ((1) Indian Institute of Technology Hyderabad, (2) Indian Institute of Technology Guwahati)🇮🇳

   We propose a self-interacting inelastic dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. Two quasi-degenerate Majorana fermion DM interact within themselves via a light hidden sector massive gauge boson and with the standard model particles via gauge kinetic mixing. We also consider an additional long-lived singlet scalar which helps in realising correct dark matter relic abundance via a hybrid setup comprising of both freeze-in and freeze-out mechanisms. While being consistent with the required DM phenomenology along with sufficient self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via inelastic down scattering of heavier DM component into the lighter one. All these requirements leave a very tiny parameter space keeping the model very predictive for near future experiments.

   hep-phastro-ph.COhep-exPRD(2021)·37 citations
5. 05*

   Precision dispersive approaches versus unitarized Chiral Perturbation Theory for the lightest scalar resonances $\sigma /f_0(500)$ and $\kappa /K_0^{\ast }(700)$

   J. R. Peláez🇪🇸 · A. Rodas🇺🇸 · J. Ruiz de Elvira🇨🇭

   For several decades, the $\sigma /f_0(500)$ and $\kappa /K_0^{\ast }(700)$ resonances have been subject to long-standing debate. Both their existence and properties were controversial until very recently. In this tutorial review we compare model-independent dispersive and analytic techniques versus unitarized Chiral Perturbation Theory, when applied to the lightest scalar mesons $\sigma /f_0(500)$ and $\kappa /K_0^{\ast }(700)$. Generically, the former have settled the long-standing controversy about the existence of these states, providing a precise determination of their parameters, whereas unitarization of chiral effective theories allows us to understand their nature, spectroscopic classification and dependence on QCD parameters. Here we review in a pedagogical way their uses, advantages and caveats.

   hep-phEur.Phys.J.ST(2021)·42 citations
6. 06*

   Studying the ${\bar{D}}_{1}K$ molecule in the Bethe-Salpeter equation approach

   Jing-Juan Qi🇨🇳 · Zhen-Yang Wang🇨🇳 · Zhu-Feng Zhang🇨🇳 · Xin-Heng Guo🇨🇳

   We interpret the $X_1(2900)$ as an $S$-wave ${\bar{D}}_{1}K$ molecular state in the Bethe-Salpeter equation approach with the ladder and instantaneous approximations for the kernel. By solving the Bethe-Salpeter equation numerically with the kernel containing one-particle-exchange diagrams and introducing three different form factors (monopole, dipole, and exponential form factors) in the verties, we find the bound state exists. We also study the decay width of the decay $X_1(2900)$ to $D^{-}{K}^{+}$.

   hep-phEPJC(2021)·23 citations
7. 07*

   Journey to the Bound States

   Paul Hoyer🇫🇮

   Guided by the observed properties of hadrons I formulate a perturbative bound state method for QED and QCD. The expansion starts with valence Fock states ($e^{+}{e}^{-},q\bar{q},qqq,gg$) bound by the instantaneous interaction of temporal gauge ($A^0=0$). The method is tested on Positronium atoms at rest and in motion, including hyperfine splitting at $O({\alpha }^4)$, electromagnetic form factors and deep inelastic scattering. Relativistic binding is studied for QED in $D=1+1$ dimensions, demonstrating the frame independence of the DIS electron distribution and its sea for $x_{bj}\to 0$. In QCD a homogeneous solution of Gauss' constraint in $D=3+1$ implies $O({\alpha }_s^0)$ confining potentials for $q\bar{q},q\bar{q}g,qqq$ and $gg$ states, whereas $q\bar{q}q\bar{q}$ is unconfined. Meson states lie on linear Regge trajectories and have the required frame dependence. A scalar bound state with vanishing four-momentum causes spontaneous chiral symmetry breaking when mixed with the vacuum. These lecture notes assume knowledge of field theory methods, but not of bound states. Brief reviews of existing bound state methods and Dirac electron states are included. Solutions to the exercises are given in the Appendix.

   hep-phnucl-thSpringerBriefs in Physics (Springer, 2021)·12 citations
8. 08*

   CP violation with GeV-scale Majorana neutrino in ${\Lambda }_b\to ({\Lambda }_c^{+},p^{+}){\pi }^{+}{\mu }^{-}{\mu }^{-}$ decays

   Diganta Das🇮🇳 · Jaydeb Das🇮🇳

   We explore the possibility of CP violation in baryonic ${\Lambda }_b\to ({\Lambda }_c^{+},p^{+}){\pi }^{+}{\mu }^{-}{\mu }^{-}$ decays which are mediated by two Majorana sterile neutrino and are $|\Delta L|=2$ lepton number violating processes. Appreciable CP asymmetry can be obtained if there are two on-shell Majorana neutrinos that are quasi-degenerate in mass with the mass difference of the order of average decay widths. We find that given the present constraints on the heavy to light mixing element $|V_{\mu N}|$, the ${\Lambda }_b\to p^{+}{\pi }^{+}{\mu }^{-}{\mu }^{-}$ and ${\Lambda }_b\to {\Lambda }_c^{+}{\pi }^{+}{\mu }^{-}{\mu }^{-}$ decay rates are suppressed but could be within the experimental reach at the LHC. If searches of the modes are performed, then experimental limits on the rates can be translated to constraints on the Majorana neutrino mass $m_N$ and heavy to light mixing element squared $|V_{\mu N}{|}^2$. We show that the constraints on the $(m_N,|V_{\mu N}{|}^2)$ parameter space coming from the $|\Delta L|=2$ baryonic decays are complementary to the bounds coming from other processes.

   hep-phPRD(2021)·8 citations
9. 09*

   Neutrino-4 anomaly: oscillations or fluctuations?

   C. Giunti🇮🇹 · Y.F. Li🇨🇳 · C.A. Ternes🇮🇹 · Y.Y. Zhang🇨🇳

   We present a deep study of the Neutrino-4 data aimed at finding the statistical significance of the large-mixing short-baseline neutrino oscillation signal claimed by the Neutrino-4 collaboration at more than $3\sigma$. We found that the results of the Neutrino-4 collaboration can be reproduced approximately only by neglecting the effects of the energy resolution of the detector. Including these effects, we found that the best fit is obtained for a mixing that is even larger, close to maximal, but the statistical significance of the short-baseline neutrino oscillation signal is only about $2.7\sigma$ if evaluated with the usual method based on Wilks' theorem. We show that the large Neutrino-4 mixing is in strong tension with the KATRIN, PROSPECT, STEREO, and solar ${\nu }_e$ bounds. Using a more reliable Monte Carlo simulation of a large set of Neutrino-4-like data, we found that the statistical significance of the Neutrino-4 short-baseline neutrino oscillation signal decreases to about $2.2\sigma$. We also show that it is not unlikely to find a best-fit point that has a large mixing, even maximal, in the absence of oscillations. Therefore, we conclude that the claimed Neutrino-4 indication in favor of short-baseline neutrino oscillations with very large mixing is rather doubtful.

   hep-phhep-exPLB(2021)·55 citations
10. 10*

    Same-Sign Dilepton Signature in the Inert Doublet Model

    Fa-Xin Yang🇨🇳 · Zhi-Long Han🇨🇳 · Yi Jin🇨🇳

    In this paper, we perform a detailed analysis on the same-sign dilepton signature in the inert doublet model. Focusing on the low dark matter mass region, we randomly scan the corresponding parameter space. Viable samples allowed by various constraints are obtained, among which twenty benchmark points are selected for further collider signature study. At hadron colliders, the same-sign dilepton signature is produced via $pp\to W^{\pm \ast }{W}^{\pm \ast }jj\to H^{\pm }{H}^{\pm }jj$ with the leptonic decay mode $H^{\pm }\to H{W}^{\pm }(\to l^{\pm }\nu )$, where $H$ is the dark matter candidate. We investigate the testability of this signal at the high-luminosity LHC (HL-LHC) and the proposed 27 TeV high-energy LHC (HE-LHC). According to our simulation, the HL-LHC with $\mathcal{L}=3a{b}^{-1}$ can hardly probe this signal. Meanwhile, for the HE-LHC with $\mathcal{L}=15a{b}^{-1}$, it is promising to obtain a $5\sigma$ significance when $250\text{GeV}\lesssim m_{H^{\pm }}-m_H\lesssim 300$ GeV with dark matter mass $m_H\sim 60$ or 71 GeV.

    hep-phCPC(2021)·11 citations
11. 11*

    Model-independent Veltman Condition, Naturalness and the Little Hierarchy Problem

    Fayez Abu-Ajamieh🇫🇷

    We adopt a bottom-up Effective Field Theory (EFT) approach to derive a model-independent Veltman condition to cancel the quadratic divergences in the Higgs mass. We show using the equivalence theorem that all deviations in the Higgs couplings to the W and Z from the SM predictions should vanish. We argue based on tree-level unitarity, that any new physics that naturally cancels the quadratic divergences should be ~19 TeV. We show that the level of fine-tuning required is O(0.1- 1%) unless the UV sector has a symmetry that forces the satisfaction of the model-independent Veltman condition, in which case all fine-tuning is eliminated. We also conjecture that if no new physics that couples to the Higgs is found up to ~ 19 TeV, or if the Higgs couplings to the SM particles conform to the SM predictions, then either the Higgs does not couple to any UV sector or is fine-tuned.

    hep-phCPC(2022)·17 citations
12. 12*

    Chiral effective Lagrangian for excited heavy-light mesons from QCD

    Qing-Sen Chen🇨🇳 · Hui-Feng Fu🇨🇳 · Yong-Liang Ma🇨🇳 · Qing Wang🇨🇳

    We derive the chiral effective Lagrangian for excited heavy-light mesons from QCD under proper approximations. We focus on the chiral partners with $j_l^P={\frac{3}{2}}^{+}$ and $j_l^P={\frac{3}{2}}^{-}$ which amounts to ($1^{+},2^{+}$) and ($1^{-},2^{-}$) states respectively. The low energy constants including the masses of the chiral partners are calculated. The calculated spectrum for the excited mesons are found roughly consistent with experimental data. In addition, our results indicate that quantum numbers of $B_J(5970)$ can be identified with $1^{-}$ or $2^{-}$.

    hep-phCommun.Theor.Phys.(2021)·1 citation
13. 13*

    Complementary Searches of Low Mass Non-Abelian Vector Dark Matter, Dark Photon and Dark $Z^{\prime }$

    Raymundo Ramos🇹🇼 · Van Que Tran🇨🇳 · Tzu-Chiang Yuan🇹🇼

    We present a novel study of the non-abelian vector dark matter candidate $W^{\prime }$ with a MeV$-$GeV low mass range, accompanied by a dark photon $A^{\prime }$ and a dark $Z^{\prime }$ of similar masses in the context of a simplified gauged two-Higgs-doublet model. The model is scrutinized by taking into account various experimental constraints including dark photon searches, electroweak precision data, relic density of dark matter together with its direct and indirect searches, mono-jet and Higgs collider physics from LHC. The viable parameter space of the model consistent with all experimental and theoretical constraints is exhibited. While a dark $Z^{\prime }$ can be the dominant contribution in the relic density due to resonant annihilation of dark matter, a dark photon is crucial to dark matter direct detection. We demonstrate that the parameter space can be further probed in the near future by sub-GeV dark matter experiments like CDEX, NEWS-G and SuperCDMS.

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

    Heavy-hadron molecular spectrum from light-meson exchange saturation

    Fang-Zheng Peng🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Mao-Jun Yan🇨🇳 · Manuel Pavon Valderrama🇨🇳

    If known, the spectrum of heavy-hadron molecules will be a key tool to disentangle the nature of the exotic states that are being discovered in experiments. Here we argue that the general features of the molecular spectrum can be deduced from the idea that the short-range interaction between the heavy hadrons is effectively described by scalar and vector meson exchange, i.e. the $\sigma$, $\omega$ and $\rho$ mesons. By means of a contact-range theory where the couplings are saturated by the aforementioned light mesons we are indeed able to postdict the $X(3872)$ (as a $D^{\ast }\bar{D}$ molecule) from the three $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ pentaquarks (as $\bar{D}{\Sigma }_c$ and ${\bar{D}}^{\ast }{\Sigma }_c$ molecules). We predict a $J^{PC}=1^{--}$ $D{\bar{D}}_1$ molecule at $4240-4260\mathrm{MeV}$ which might support the hypothesis that the $Y(4260)$ is at least partly molecular. The extension of these ideas to the light baryons requires minor modifications, after which we recover approximate SU(4)-Wigner symmetry in the two-nucleon system and approximately reproduce the masses of the deuteron and the virtual state.

    hep-phhep-exhep-latnucl-thPRD(2022)·33 citations
15. 15*

    Next-to-leading power threshold corrections for finite order and resummed colour-singlet cross sections

    Melissa van Beekveld🇳🇱 · Eric Laenen🇳🇱 · Jort Sinninghe Damsté🇳🇱 · Leonardo Vernazza🇮🇹

    We study next-to-leading-power (NLP) threshold corrections in colour-singlet production processes, with particular emphasis on Drell-Yan (DY) and single-Higgs production. We assess the quality of the partonic and hadronic threshold expansions for each process up to NNLO. We determine numerically the NLP leading-logarithmic (LL) resummed contribution in addition to the leading-power next-to-next-to-leading logarithmic (LP NNLL) resummed DY and Higgs cross sections, matched to NNLO. We find that the inclusion of NLP logarithms is numerically more relevant than increasing the precision to N${}^3$LL at LP for these processes. We also perform an analytical and numerical comparison of LP NNLL + NLP LL resummation in soft-collinear effective theory and direct QCD, where we achieve excellent analytical and numerical agreement once the NLP LL terms are included in both formalisms. Our results underline the phenomenological importance of understanding the NLP structure of QCD cross sections.

    hep-phJHEP(2021)·45 citations
16. 16*

    The Flavor of UV Physics

    Sebastian Bruggisser🇩🇪 · Ruth Schäfer🇩🇪 · Danny van Dyk🇩🇪 · Susanne Westhoff🇩🇪

    New physics not far above the TeV scale should leave a pattern of virtual effects in observables at lower energies. What do these effects tell us about the flavor structure of a UV theory? Within the framework of Standard Model Effective Field Theory (SMEFT), we resolve the flavor structure of the Wilson coefficients in a combined analysis of top-quark and $B$-physics observables. Our fit to LHC and $b$-factory measurements shows that combining top and bottom observables is crucial to pin down possible sources of flavor symmetry breaking from UV physics. Our analysis includes the full analytic expansion of SMEFT coefficients in Minimal Flavor Violation and a detailed study of SMEFT effects in $b\to s$ flavor transitions.

    hep-phhep-exJHEP(2021)·89 citations
17. 17*

    Z_c -like spectra from QCD Laplace sum rules at NLO

    R.M. Albuquerque (FAT-Univ. Rio de Janeiro, BR)🇧🇷 · S. Narison (LUPM-CNRS Montpellier, FR and iHEPMAD-Univ. Antananarivo, MG)🇫🇷 · D. Rabetiarivony (iHEPMAD-Univ. Antananarivo, MG)🇲🇬

    We present a global analysis of the observed Z_c, Z_cs and future Z_css-like spectra using the inverse Laplace transform (LSR) version of QCD spectral sum rules (QSSR) within stability criteria. Integrated compact QCD expressions of the LO spectral functions up to dimension-six condensates are given. Next-to-Leading Order (NLO) factorized perturbative contributions are included. We re-emphasize the importance to include PT radiative corrections (though numerically small) for heavy quark sum rules in order to justify the (ad hoc) definition and value of the heavy quark mass used frequently at LO in the literature. We also demonstrate that, contrary to a naïve qualitative 1/N_c counting, the two-meson scattering contributions to the four-quark spectral functions are numerically negligible confirming the reliability of the LSR predictions. Our results are summarized in Tables III to VI. The Z_c(3900) and Z_cs(3983) spectra are well reproduced by the T_c(3900) and T_cs(3973) tetramoles (superposition of quasi-degenerated molecules and tetraquark states having the same quantum numbers and with almost equal couplings to the currents). The Z_c(4025) or Z_c(4040) state can be fitted with the D*_0D_1 molecule having a mass 4023(130) MeV while the Z_cs bump around 4.1 GeV can be likely due to the (D^*_s0D_1+ D^*_0D_s1) molecules. The Z_c(4430) can be a radial excitation of the Z_c(3900) weakly coupled to the current, while all strongly coupled ones are in the region (5634-6527) MeV. The double strange tetramole state T_css which one may identify with the future Z_css is predicted to be at 4064(46) MeV. It is remarkable to notice the regular mass-spliitings of the tetramoles due to SU(3) breakings M_{T_cs}-M_{T_c}= M_{T_css}-M_{T_cs= (73- 91) MeV.

    hep-phhep-exhep-latnucl-thPRD(2021)·52 citations
18. 18*

    The relic neutrino composition as seen from Earth

    Anton N. Baushev🇷🇺

    Being generated, the relic neutrino background contained equal fractions of electron ${\nu }_e$, muon ${\nu }_{\mu }$, and taon ${\nu }_{\tau }$ neutrinos. We show that the gravitational field of our Galaxy and other nearby cosmic objects changes this composition near the Solar System, enriching it with the heaviest neutrino $n{u}_3$. This mass state is almost free of the electron component (only $\sim 2\%$ of ${\nu }_e$) and contains more muon component than the tau one. As a result, the relic background becomes enriched with taon and particularly muon neutrinos. The electron relic neutrinos are the rarest for a terrestrial observer: instead of $1/3$, the relic background may contain only $\gtrsim 20\%$ of them.

    hep-phastro-ph.COastro-ph.HEhep-thAstron.Rep.(2020)·4 citations
19. 19*

    Velocity-dependent J-factors for annihilation radiation from cosmological simulations

    Erin Board🇺🇸 · Nassim Bozorgnia🇨🇦 · Louis E. Strigari🇺🇸 · Robert J. J. Grand🇩🇪 · Azadeh Fattahi🇬🇧 · Carlos S. Frenk🇬🇧 · Federico Marinacci🇮🇹 · Julio F. Navarro🇨🇦 · Kyle A. Oman🇬🇧

    We determine the dark matter pair-wise relative velocity distribution in a set of Milky Way-like halos in the Auriga and APOSTLE simulations. Focusing on the smooth halo component, the relative velocity distribution is well-described by a Maxwell-Boltzmann distribution over nearly all radii in the halo. We explore the implications for velocity-dependent dark matter annihilation, focusing on four models which scale as different powers of the relative velocity: Sommerfeld, s-wave, p-wave, and d-wave models. We show that the J-factors scale as the moments of the relative velocity distribution, and that the halo-to-halo scatter is largest for d-wave, and smallest for Sommerfeld models. The J-factor is strongly correlated with the dark matter density in the halo, and is very weakly correlated with the velocity dispersion. This implies that if the dark matter density in the Milky Way can be robustly determined, one can accurately predict the dark matter annihilation signal, without the need to identify the dark matter velocity distribution in the Galaxy.

    ↳ astro-ph.COastro-ph.GAhep-phJCAP(2021)·28 citations
20. 20*

    Axial $U_A(1)$ Anomaly: a New Mechanism to Generate Massless Bosons

    Vicente Azcoiti🇪🇸

    Prior to the establishment of $QCD$ as the correct theory describing hadronic physics, it was realized that the essential ingredients of the hadronic world at low energies are chiral symmetry and its spontaneous breaking. Spontaneous symmetry breaking is a non-perturbative phenomenon and thanks to massive $QCD$ simulations on the lattice we have at present a good understanding on the vacuum realization of the non-abelian chiral symmetry as a function of the physical temperature. As far as the $U_A(1)$ anomaly is concerned, and especially in the high temperature phase, the current situation is however far from satisfactory. The first part of this article is devoted to review the present status of lattice calculations, in the high temperature phase of $QCD$, of quantities directly related to the $U_A(1)$ axial anomaly. In the second part I will analyze some interesting physical implications of the $U_A(1)$ anomaly, recently suggested, in systems where the non-abelian axial symmetry is fulfilled in the vacuum. More precisely I will argue that, if the $U_A(1)$ symmetry remains effectively broken, the topological properties of the theory can be the basis of a mechanism, other than Goldstone's theorem, to generate a rich spectrum of massless bosons at the chiral limit.

    ↳ hep-lathep-phhep-thSymmetry(2021)·6 citations
21. 21*

    Non-tensorial Gravitational Wave Background in NANOGrav 12.5-Year Data Set

    Zu-Cheng Chen🇨🇳 · Chen Yuan🇨🇳 · Qing-Guo Huang🇨🇳

    We perform the first search for an isotropic non-tensorial gravitational-wave background (GWB) allowed in general metric theories of gravity in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 12.5-year data set. By modeling the GWB as a power-law spectrum, we find strong Bayesian indication for a spatially correlated process with scalar transverse (ST) correlations whose Bayes factor versus the spatially uncorrelated common-spectrum process is $107\pm 7$, but no statistically significant evidence for the tensor transverse, vector longitudinal and scalar longitudinal polarization modes. The median and the $90\%$ equal-tail amplitudes of ST mode are ${\mathcal{A}}_{\mathrm{ST}}=1.06_{-0.28}^{+0.35}\times 10^{-15}$, or equivalently the energy density parameter per logarithm frequency is ${\Omega }_{\mathrm{GW}}^{\mathrm{ST}}=1.54_{-0.71}^{+1.21}\times 10^{-9}$, at frequency of 1/year.

    ↳ astro-ph.COgr-qchep-phhep-thSCPMA(2021)·81 citations
22. 22*

    Precessing magnetars as central engines in short gamma-ray bursts

    Arthur G. Suvorov🇩🇪 · Kostas D. Kokkotas🇩🇪

    Short gamma-ray bursts that are followed by long-duration X-ray plateaus may be powered by the birth, and hydrodynamic evolution, of magnetars from compact binary coalescence events. If the rotation and magnetic axes of the system are not orthogonal to each other, the star will undergo free precession, leading to fluctuations in the luminosity of the source. In some cases, precession-induced modulations in the spin-down power may be discernible in the X-ray flux of the plateau. In this work, 25 X-ray light curves associated with bursts exhibiting a plateau are fitted to luminosity profiles appropriate for precessing, oblique rotators. Based on the Akaike Information Criterion, 16 (64 per cent) of the magnetars within the sample display either moderate or strong evidence for precession. Additionally, since the precession period of the star is directly tied to its quadrupolar ellipticity, the fits allow for an independent measure of the extent to which the star is deformed by internal stresses. Assuming these deformations arise due to a mixed poloidal-toroidal magnetic field, we find that the distribution of magnetic-energy ratios is bimodal, with data points clustering around energetically equal and toroidally dominated partitions. Implications of this result for gravitational-wave emission and dynamo activity in newborn magnetars are discussed.

    ↳ astro-ph.HEhep-phMNRAS(2021)·27 citations
23. 23*

    Phase transition of four-dimensional lattice ${\varphi }^4$ theory with tensor renormalization group

    Shinichiro Akiyama🇯🇵 · Yoshinobu Kuramashi🇯🇵 · Yusuke Yoshimura🇯🇵

    We investigate the phase transition of the four-dimensional single-component ${\varphi }^4$ theory on the lattice using the tensor renormalization group method. We have examined the hopping parameter dependence of the bond energy and the vacuum condensation of the scalar field $⟨\varphi ⟩$ at a finite quartic coupling $\lambda$ on large volumes up to $V=1024^4$ in order to detect the spontaneous breaking of the ${\mathbb{Z}}_2$ symmetry. Our results show that the system undergoes the weak first-order phase transition at a certain critical value of the hopping parameter. We also make a comparative study of the three-dimensional ${\varphi }^4$ theory and find that the properties of the phase transition are consistent with the universality class of the three-dimensional Ising model.

    ↳ hep-lathep-phhep-thPRD(2021)·29 citations
24. 24*

    Charge-Swapping Q-balls and Their Lifetimes

    Qi-Xin Xie🇨🇳 · Paul M. Saffin🇬🇧 · Shuang-Yong Zhou🇨🇳

    For scalar theories accommodating spherically symmetric Q-balls, there are also towers of quasi-stable composite Q-balls, called charge swapping Q-balls (CSQs). We investigate the properties, particularly the lifetimes, of these long-lived CSQs in 2+1D and 3+1D using numerical simulations with efficient second order absorbing boundary conditions. We find that the evolution of a CSQ typically consists of 4 distinct stages: initial relaxation, first plateau (CSQ stage), fast decay and second plateau (oscillon stage). We chart the lifetimes of CSQs for different parameters of the initial conditions and of the potential, and show the attractor behavior and other properties of the CSQs.

    ↳ hep-thastro-ph.COhep-phJHEP(2021)·27 citations
25. 25*

    Spinning-off stringy electro-magnetic memories

    Alice Aldi🇮🇹 · Massimo Bianchi🇮🇹 · Maurizio Firrotta🇮🇹

    We extend and generalise the string corrections to the EM memory to the Type I superstring including spin effects. Very much as in the simpler bosonic string context, the relevant corrections are non-perturbative in ${\alpha }^{\prime }$, slowly decaying (as $1/R$) at large distances and modulated in retarded time $u=t-R$. For spin $N$ states in the first Regge trajectory they entail a sequence of $N$ derivatives wrt $u$ on the `parent' $N=0$ amplitude. We also briefly discuss how to include loop effects, that broaden and shift the string resonances, and how to modify our analysis for macroscopic semi-classical quasi-BPS coherent states, whose collisions may lead to detectable string memory signals in viable Type I models.

    ↳ hep-thhep-phNPB(2022)·12 citations
26. 26*

    Manifestation of Hidden Symmetries in Baryonic Matter: From Finite Nuclei to Neutron Stars

    Mannque Rho🇫🇷 · Yong-Liang Ma🇨🇳

    The hadron-quark/gluon duality formulated in terms of a topology change at a density $n\text{gsim}2n_0$ $n_0\simeq 0.16$fm${}^{-3}$ is found to describe the core of massive compact stars in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor like deconfined quarks. This can be considered as the Cheshire-Cat mechanism~\cite{CC} for the hadron-quark continuity arrived at bottom-up from skyrmions that is equivalent to the "MIT-bag"-to-skyrmion continuity arrived at top-down from quarks/gluons. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise both to the long-standing "effective $g_A^{\ast }\approx 1$" in nuclear Gamow-Teller transitions at $\text{lsim}{n}_0$ and to the pseudo-conformal sound velocity $v_{pcs}^2/c^2\approx 1/3$ at $\text{gsim}3n_0$. It is suggested that what has been referred to, since a long time, as "quenched $g_A$" in light nuclei reflects what leads to the dilaton-limit $g_A^{\mathrm{DL}}=1$ at near the (putative) infrared fixed point of scale invariance. These properties are confronted with the recent observations in Gamow-Teller transitions and in astrophysical observations.

    ↳ nucl-thastro-ph.HEhep-phMod.Phys.Lett.A(2021)·28 citations
27. 27*

    Comment on "${\Lambda }_{c}N$ interaction in leading order covariant chiral effective field theory"

    J. Haidenbauer🇩🇪 · G. Krein🇧🇷

    Song et al. [Phys. Rev. C 102, 065208 (2020)] presented results for the ${\Lambda }_{c}N$ interaction based on an extrapolation of lattice simulations by the HAL QCD Collaboration at unphysical quark masses to the physical point via covariant chiral effective field theory. We point out that their predictions for the ${}^3{D}_1$ partial wave disagree with available lattice results. We discuss the origin of that disagreement and present a comparison with predictions from conventional (non-relativistic) chiral effective field theory.

    ↳ nucl-thhep-ph4 citations
28. 28*

    Contribution of the QCD $\Theta$-term to nucleon electric dipole moment

    Tanmoy Bhattacharya🇺🇸 · Vincenzo Cirigliano🇺🇸 · Rajan Gupta🇺🇸 · Emanuele Mereghetti🇺🇸 · Boram Yoon (Los Alamos National Laboratory)🇺🇸

    We present a calculation of the contribution of the $\Theta$-term to the neutron and proton electric dipole moments using seven 2+1+1-flavor HISQ ensembles. We also estimate the topological susceptibility for the 2+1+1 theory to be ${\chi }_Q=(66(9)(4)\mathrm{MeV}{)}^4$ in the continuum limit at $M_{\pi }=135$ MeV. The calculation of the nucleon three-point function is done using Wilson-clover valence quarks. The CP-violating form factor $F_3$ is calculated by expanding in small $\Theta$. We show that lattice artifacts introduce a term proportional to $a$ that does not vanish in the chiral limit, and we include this in our chiral-continuum fits. A chiral perturbation theory analysis shows that the $N(0)\pi (0)$ state should provide the leading excited state contribution, and we study the effect of such a state. Detailed analysis of the contributions to the neutron and proton electric dipole moment using two strategies for removing excited state contamination are presented. Using the excited state spectrum from fits to the two-point function, we find $d_n^{\Theta }$ is small, $|d_n^{\Theta }|\lesssim 0.01\overline{\Theta }e$ fm, whereas for the proton we get $|d_p^{\Theta }|\sim 0.02\overline{\Theta }e$ fm. On the other hand, if the dominant excited-state contribution is from the $N\pi$ state, then $|d_n^{\Theta }|$ could be as large as $0.05\overline{\Theta }e$ fm and $|d_p^{\Theta }|\sim 0.07\overline{\Theta }e$ fm. Our overall conclusion is that present lattice QCD calculations do not provide a reliable estimate of the contribution of the $\Theta$-term to the nucleon electric dipole moments, and a factor of ten higher statistics data are needed to get better control over the systematics and possibly a $3\sigma$ result.

    ↳ hep-lathep-phPRD(2021)·67 citations
29. 29*

    Scattering Amplitudes and Conservative Binary Dynamics at $\mathcal{O}(G^4)$

    Zvi Bern🇺🇸 · Julio Parra-Martinez🇺🇸 · Radu Roiban🇺🇸 · Michael S. Ruf🇩🇪 · Chia-Hsien Shen🇺🇸 · Mikhail P. Solon🇺🇸 · Mao Zeng🇬🇧

    Using scattering amplitudes, we obtain the potential contributions to conservative binary dynamics in general relativity at fourth post-Minkowskian order, $\mathcal{O}(G^4)$. As in previous lower-order calculations, we harness powerful tools from the modern scattering amplitudes program including generalized unitarity, the double copy, and advanced multiloop integration methods, in combination with effective field theory. The classical amplitude involves polylogarithms with up to transcendental weight two and elliptic integrals. We derive the radial action directly from the amplitude, and determine the corresponding Hamiltonian in isotropic gauge. Our results are in agreement with known overlapping terms up to sixth post-Newtonian order, and with the probe limit. We also determine the post-Minkowskian energy loss from radiation emission at $\mathcal{O}(G^3)$ via its relation to the tail effect.

    ↳ hep-thgr-qchep-phPRL(2021)·398 citations
30. 30*

    Gravitational Bremsstrahlung from Reverse Unitarity

    Enrico Herrmann🇺🇸 · Julio Parra-Martinez🇺🇸 · Michael S. Ruf🇩🇪 · Mao Zeng🇬🇧

    We compute the total radiated momentum carried by gravitational waves during the scattering of two spinless black holes at the lowest order in Newton's constant, $\mathcal{O}(G^3)$, and all orders in velocity. By analytic continuation into the bound state regime, we obtain the $\mathcal{O}(G^3)$ energy loss in elliptic orbits. This provides an essential step towards the complete understanding of the third-post-Minkowskian binary dynamics. We employ the formalism of Kosower, Maybee, and O'Connell (KMOC) which relates classical observables to quantum scattering amplitudes and derive the relevant integrands using generalized unitarity. The subsequent phase-space integrations are performed via the reverse unitarity method familiar from collider physics, using differential equations to obtain the exact velocity dependence from near-static boundary conditions.

    ↳ hep-thgr-qchep-phPRL(2021)·195 citations
31. 31*

    E Pluribus Unum Ex Machina: Learning from Many Collider Events at Once

    Benjamin Nachman🇺🇸 · Jesse Thaler🇺🇸

    There have been a number of recent proposals to enhance the performance of machine learning strategies for collider physics by combining many distinct events into a single ensemble feature. To evaluate the efficacy of these proposals, we study the connection between single-event classifiers and multi-event classifiers under the assumption that collider events are independent and identically distributed (IID). We show how one can build optimal multi-event classifiers from single-event classifiers, and we also show how to construct multi-event classifiers such that they produce optimal single-event classifiers. This is illustrated for a Gaussian example as well as for classification tasks relevant for searches and measurements at the Large Hadron Collider. We extend our discussion to regression tasks by showing how they can be phrased in terms of parametrized classifiers. Empirically, we find that training a single-event (per-instance) classifier is more effective than training a multi-event (per-ensemble) classifier, as least for the cases we studied, and we relate this fact to properties of the loss function gradient in the two cases. While we did not identify a clear benefit from using multi-event classifiers in the collider context, we speculate on the potential value of these methods in cases involving only approximate independence, as relevant for jet substructure studies.

    ↳ physics.data-anhep-exhep-phstat.MLPRD(2021)·51 citations
32. 32*

    Self-gravitating Vector Dark Matter

    Peter Adshead🇺🇸 · Kaloian D. Lozanov🇺🇸

    We derive the non-relativistic limit of a massive vector field. We show that the Cartesian spatial components of the vector behave as three identical, non-interacting scalar fields. We find classes of spherical, cylindrical, and planar self-gravitating vector solitons in the Newtonian limit. The gravitational properties of the lowest-energy vector solitons$-$the gravitational potential and density field$-$depend only on the net mass of the soliton and the vector particle mass. In particular, these self-gravitating, ground-state vector solitons are independent of the distribution of energy across the vector field components, and are indistinguishable from their scalar-field counterparts. Fuzzy Vector Dark Matter models can therefore give rise to halo cores with identical observational properties to the ones in scalar Fuzzy Dark Matter models. We also provide novel hedgehog vector soliton solutions, which cannot be observed in scalar-field theories. The gravitational binding of the lowest-energy hedgehog halo is about three times weaker than the ground-state vector soliton. Finally, we show that no spherically symmetric solitons exist with a divergence-free vector field.

    ↳ gr-qcastro-ph.COhep-phPRD(2021)·57 citations
33. 33*

    Gopakumar-Vafa Hierarchies in Winding Inflation and Uplifts

    Federico Carta🇬🇧 · Alessandro Mininno🇪🇸 · Nicole Righi🇩🇪 · Alexander Westphal🇩🇪

    We propose a combined mechanism to realize both winding inflation and de Sitter uplifts. We realize the necessary structure of competing terms in the scalar potential not via tuning the vacuum expectation values of the complex structure moduli, but by a hierarchy of the Gopakumar-Vafa invariants of the underlying Calabi-Yau threefold. To show that Calabi-Yau threefolds with the prescribed hierarchy actually exist, we explicitly create a database of all the genus $0$ Gopakumar-Vafa invariants up to total degree $10$ for all the complete intersection Calabi-Yau's up to Picard number $9$. As a side product, we also identify all the redundancies present in the CICY list, up to Picard number $13$. Both databases can be accessed at this link: https://www.desy.de/~westphal/GV_CICY_webpage/GVInvariants.html .

    ↳ hep-thastro-ph.COhep-phJHEP(2021)·24 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.