Thu·Jul 2, 2020Thursday·July 2, 2020

1. 01*

   Separation of Quark Flavors using DVCS Data

   Marija Cuic🇭🇷 · Kresimir Kumericki🇭🇷 · Andreas Schafer🇩🇪

   Using the available data on deeply virtual Compton scattering (DVCS) off protons and utilizing neural networks enhanced by the dispersion relation constraint, we determine six out of eight leading Compton form factors in the valence quark kinematic region. Furthermore, adding recent data on DVCS off neutrons, we separate contributions of up and down quarks to the dominant form factor, thus paving the way towards a three-dimensional picture of the nucleon.

   hep-phhep-exPRL(2020)·56 citations
2. 02*

   Mirror neutrons as dark matter in the Mirror Twin Two Higgs Doublet Model

   Hugues Beauchesne🇮🇱

   In addition to being a solution to the little hierarchy problem, the Mirror Twin Higgs provides a natural setting for Asymmetric Dark Matter. In its incarnation with only one Higgs doublet and its mirror copy, dark matter would however almost certainly consist mostly of mirror atoms, which is severely ruled out by constraints on dark matter self-interactions. By adding a second Higgs doublet and its mirror, the vevs of the different Higgses can be arranged such that dark matter consists mostly of mirror neutrons, which is cosmologically viable. In this paper, it is shown that current constraints from colliders, flavour and cosmology can accommodate such a vev structure with little increase in the necessary tuning.

   hep-phJHEP(2020)·21 citations
3. 03*

   Neutrino decoherence from quantum gravitational stochastic perturbations

   Thomas Stuttard🇩🇰 · Mikkel Jensen🇩🇰

   Neutrinos undergoing stochastic perturbations as they propagate experience decoherence, damping neutrino oscillations over distance. Such perturbations may result from fluctuations in space-time itself if gravity is a quantum force, including interactions between neutrinos and virtual black holes. In this work we model the influence of heuristic neutrino-virtual black hole interaction scenarios on neutrino propagation and evaluate the resulting signals in astrophysical and atmospheric neutrinos. We demonstrate how these effects can be represented in the framework of open quantum systems, allowing experimental constraints on such systems to be connected to quantum gravitational effects. Finally, we consider the energy-dependence of such Planck scale physics at energies observed in current neutrino experiments, and show that sensitivity to Planck scale physics well below the `natural' expectation is achievable in certain scenarios.

   hep-phgr-qchep-exPRD(2020)·52 citations
4. 04*

   Dynamical Mass Generation in Wick Cutkosky Model

   Tajdar Mufti🇵🇰

   Studying extent of dynamical generation of mass in a quantum field theory, which may have non-perturbative attributes, is an essential step towards complete understanding of the theory. It has historic relevance to interactions including fermions. However, as search of further fundamental scalars continues, inquiring into the possibility of dynamical generation of mass becomes crucial for scalars with masses much lower than the electroweak scale. This paper addresses Yukawa interaction between a complex doublet field, conveniently named the Higgs, and a scalar singlet studied in terms of correlation functions and the dynamical masses produced in the parameter space of the model. The study is conducted using the method of Dyson Schwinger equation. The Higgs is found to be receiving negative squared masses while the scalar singlet field receives positive squared mass. Higgs propagators are found to be significantly more sensitive to couplings in comparison to the scalar propagators. The vertices are relatively more stable against the cutoff used in comparison to the propagators and dynamically generated masses. No indication of a critical coupling is found within the explored range of coupling values. The model is found to have strong cutoff effects until the cutoff is raised to 100 TeV. The model suggests no sign of triviality.

   hep-phhep-th0 citations
5. 05*

   Boosted jet techniques for a supersymmetric scenario with gravitino LSP

   Akanksha Bhardwaj🇮🇳 · Juhi Dutta🇩🇪 · Partha Konar🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Santosh Kumar Rai🇮🇳

   Search for compressed supersymmetry at multi-TeV scale, in the presence of a light gravitino dark matter, can get sizable uplift while looking into the associated fat-jets with missing transverse momenta as a signature of the boson produced in the decay process of much heavier next-to-lightest sparticle. We focus on the hadronic decay of the ensuing Higgs and/or $Z$ boson giving rise to at least two fat-jets and $\text{slashed}{E}_T$ in the final state. We perform a detailed background study adopting a multivariate analysis using a boosted decision tree to provide a robust investigation to explore the discovery potential for such signal at 14 TeV LHC considering different benchmark points satisfying all the theoretical and experimental constraints. This channel provides the best discovery prospects with most of the benchmarks discoverable within an integrated luminosity of $\mathcal{L}=200$ fb${}^{-1}$. Kinematic observables are investigated in order to distinguish between compressed and uncompressed spectra having similar event yields.

   hep-phJHEP(2020)·9 citations
6. 06*

   Active-sterile neutrino mixing constraint using reactor antineutrinos with the ISMRAN set-up

   S. P. Behera🇮🇳 · D. K. Mishra🇮🇳 · L. M. Pant🇮🇳

   In this work, we present an analysis of the sensitivity to the active-sterile neutrino mixing with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up at very short baseline. In this article, we have considered the measurement of electron antineutrino induced events employing a single detector which can be placed either at a single position or moved between near and far positions from the given reactor core. Results extracted in the later case are independent of the theoretical prediction of the reactor anti-neutrino spectrum and detector related systematic uncertainties. Our analysis shows that the results obtained from the measurement carried out at a combination of the near and far detector positions are improved significantly at higher $\Delta m_{41}^2$ compared to the ones obtained with the measurement at a single detector position only. It is found that the best possible combination of near and far detector positions from a 100 MW${}_{th}$ power DHRUVA research reactor core are 7 m and 9 m, respectively, for which ISMRAN set-up can exclude in the range 1.4 $e{V}^2\le \Delta m_{41}^2\le$ 4.0 $e{V}^2$ of reactor antineutrino anomaly region along with the present best-fit point of active-sterile neutrino oscillation parameters. At those combinations of detector positions, the ISMRAN set-up can observe the active sterile neutrino oscillation with a 95$\%$ confidence level provided that ${\sin }^{2}2{\theta }_{14}\ge 0.09$ at $\Delta m_{41}^2$ = 1 eV${}^2$ for an exposure of 1 ton-yr. The active-sterile neutrino mixing sensitivity can be improved by about 22\% at the same exposure by placing the detector at near and far distances of 15 m and 17 m, respectively, from the compact proto-type fast breeder reactor (PFBR) facility which has a higher thermal power of 1250 MW${}_{th}$.

   hep-phnucl-exnucl-thphysics.ins-detPRD(2020)·15 citations
7. 07*

   Reduction of Feynman Integrals in the Parametric Representation III: Integrals with Cuts

   Wen Chen🇨🇦

   Phase space cuts are implemented by inserting Heaviside theta functions in the integrands of momentum-space Feynman integrals. By directly parametrizing theta functions and constructing integration-by-parts (IBP) identities in the parametric representation, we provide a systematic method to reduce integrals with cuts. Since the IBP method is available, it becomes possible to evaluate integrals with cuts by constructing and solving differential equations.

   hep-phEPJC(2020)·19 citations
8. 08*

   Implications of $A_4$ modular symmetry on Neutrino mass, Mixing and Leptogenesis with Linear Seesaw

   Mitesh Kumar Behera🇮🇳 · Subhasmita Mishra🇮🇳 · Shivaramakrishna Singirala🇮🇳 · Rukmani Mohanta🇮🇳

   The present work is inspired by the application of $A_4$ modular symmetry in the linear seesaw framework, which restricts the use of multiple flavon fields. Linear seesaw is realized with six heavy $SU(2{)}_L$ singlet fermion superfields and a weighton in a supersymmetric framework. The non-trivial transformation of Yukawa couplings under the $A_4$ modular symmetry helps to explore the neutrino phenomenology with a specific flavor structure of the mass matrix. We discuss the phenomena of neutrino mixing and show that the obtained mixing angles and CP violating phase in this framework are compatible with the observed $3\sigma$ range of the current oscillation data. In addition, we also investigate the non-zero CP asymmetry from the decay of lightest heavy fermion superfield to explain the preferred phenomena of baryogenesis through leptogenesis including flavor effects.

   hep-phPhys.Dark Univ.(2022)·83 citations
9. 09*

   Exact SMEFT formulation and expansion to $\mathcal{O}(v^4/{\Lambda }^4)$

   Chris Hays🇬🇧 · Andreas Helset🇩🇰 · Adam Martin🇺🇸 · Michael Trott🇩🇰

   The Standard Model Effective Field Theory (SMEFT) theoretical framework is increasingly used to interpret particle physics measurements and constrain physics beyond the Standard Model. We investigate the truncation of the effective-operator expansion using the geometric formulation of the SMEFT, which allows exact solutions, up to mass-dimension eight. Using this construction, we compare the exact solution to the expansion at $\mathcal{O}(v^2/{\Lambda }^2)$, partial $\mathcal{O}(v^4/{\Lambda }^4)$ using a subset of terms with dimension-6 operators, and full $\mathcal{O}(v^4/{\Lambda }^4)$, where $v$ is the vacuum expectation value and $\Lambda$ is the scale of new physics. This comparison is performed for general values of the coefficients, and for the specific model of a heavy U(1) gauge field kinetically mixed with the Standard Model. We additionally determine the input-parameter scheme dependence at all orders in $v/\Lambda$, and show that this dependence increases at higher orders in $v/\Lambda$.

   hep-phJHEP(2020)·67 citations
10. 10*

    Newly discovered ${\Xi }_c^0$ resonances and their parameters

    S. S. Agaev🇦🇿 · K. Azizi🇮🇷 · H. Sundu🇹🇷

    The aim of the present article is investigation of the newly observed resonances ${\Xi }_c(2923{)}^0$, ${\Xi }_c(2939{)}^0$, and ${\Xi }_c(2965{)}^0$ which are real candidates to charm-strange baryons. To this end, we calculate the mass and pole residue of the ground-state and excited $1P$ and $2S$ spin- flavor-sextet baryons ${\Xi }_c^{\prime 0}$, ${\Xi }_c^{\prime 0}(1/2^{-})$ and ${\Xi }_c^{\prime 0}(1/2^{+})$ with quark content $csd$, respectively. The masses and pole residues of the ground-state and excited spin-$3/2$ baryons ${\Xi }_c^{\star 0}$ are found as well. Spectroscopic parameters of these particles are computed in the context of the QCD two-point sum rule method. Widths of the excited baryons are evaluated through their decays to final states ${\Lambda }_c^{+}{K}^{-}$ and . These processes are explored by means of the full QCD light-cone sum rule method necessary to determine strong couplings at relevant vertices. Obtained predictions for the masses and widths of the four excited baryons, as well as previous results for $1P$ and $2S$ flavor-antitriplet spin-1/2 particles ${\Xi }_c^0$ are confronted with available experimental data on ${\Xi }_c^0$ resonances to fix their quantum numbers. Our comparison demonstrates that the resonances ${\Xi }_c(2923{)}^0$ and ${\Xi }_c(2939{)}^0$ can be considered as $1P$ excitations of the spin-$1/2$ flavor-sextet and spin-$3/2$ baryons, respectively. The resonance ${\Xi }_c(2965{)}^0$ may be interpreted as the excited $2S$ state of either spin- flavor-sextet or antitriplet baryon.

    hep-phhep-exhep-latEPJA(2021)·17 citations
11. 11*

    Missing in Axion: where are XENON1T's big black holes?

    Djuna Croon🇨🇦 · Samuel D. McDermott🇺🇸 · Jeremy Sakstein🇺🇸

    We pioneer the black hole mass gap as a powerful new tool for constraining new particles. A new particle that couples to the Standard Model---such as an axion---acts as an additional source of loss in the cores of population-III stars, suppressing mass lost due to winds and quenching the pair-instability. This results in heavier astrophysical black holes. As an example, using stellar simulations we show that the solar axion explanation of the recent XENON1T excess implies astrophysical black holes of ~ 56 MS, squarely within the black hole mass gap predicted by the Standard Model.

    hep-phastro-ph.COastro-ph.GAastro-ph.HE+1Phys.Dark Univ.(2021)·36 citations
12. 12*

    Precision tests of fundamental physics with $\eta$ and ${\eta }^{\prime }$ mesons

    Liping Gan🇺🇸 · Bastian Kubis🇩🇪 · Emilie Passemar🇺🇸 · Sean Tulin🇨🇦

    Decays of the neutral and long-lived $\eta$ and ${\eta }^{\prime }$ mesons provide a unique, flavor-conserving laboratory to test low-energy Quantum Chromodynamics and search for new physics beyond the Standard Model. They have drawn world-wide attention in recent years and have inspired broad experimental programs in different high-intensity-frontier centers. New experimental data will offer critical inputs to precisely determine the light quark mass ratios, $\eta$-${\eta }^{\prime }$ mixing parameters, and hadronic contributions to the anomalous magnetic moment of the muon. At the same time, it will provide a sensitive probe to test potential new physics. This includes searches for hidden photons, light Higgs scalars, and axion-like particles that are complementary to worldwide efforts to detect new light particles below the GeV mass scale, as well as tests of discrete symmetry violation. In this review, we give an update on theoretical developments, discuss the experimental opportunities, and identify future research needed in this field.

    hep-phhep-exnucl-exnucl-thPhys.Rept.(2022)·179 citations
13. 13*

    Long range dark matter self-interactions and plasma instabilities

    Robert Lasenby🇺🇸

    So far, the observed effects of dark matter are compatible with it having purely gravitational interactions. However, in many models, dark matter has additional interactions with itself, with the Standard Model, and/or with additional hidden sector states. In this paper, we discuss models in which dark matter interacts through a light vector mediator, giving rise to a long-ranged force between dark matter particles. Coherent scattering effects through this force can lead to the exponential growth of small perturbations, in analogy to electromagnetic plasma instabilities. These instabilities can be significant at couplings many orders of magnitude below those for which the usual particle-by-particle constraints on dark matter self-interactions apply. While this possibility has been noted in the literature, we provide the first systematic study of such instabilities, including the case where the mediator has finite mass. The latter is relevant for models of kinetically mixed `dark photon' mediators, which represent an important target for proposed dark matter detection experiments. Our analyses are of the growth of small perturbations, so do not immediately provide observational constraints on dark matter models - however, they do motivate further study of large regions of parameter space.

    hep-phastro-ph.COJCAP(2020)·41 citations
14. 14*

    The effective field theory of low scale see-saw at colliders

    Anke Biekötter🇬🇧 · Mikael Chala🇪🇸 · Michael Spannowsky🇬🇧

    We study the Standard Model effective field theory ($\nu$SMEFT) extended with operators involving right-handed neutrinos, focussing on the regime where the right-handed neutrinos decay promptly on collider scales to a photon and a Standard Model neutrino. This scenario arises naturally for right-handed neutrinos with masses of the order $m_N\sim 0.1\dots 10\text{GeV}$. We limit the relevant dimension-six operator coefficients using LEP and LHC searches with photons and missing energy in the final state as well as pion and tau decays. While bounds on new physics contributions are generally in the TeV scale for order one operator coefficients, some coefficients, however, remain very poorly constrained or even entirely evade bounds from current data. Consequently, we identify such weakly constrained scenarios and propose new searches for rare top and tau decays involving photons to probe potential new physics in the $\nu$SMEFT parameter space. Our analysis highlights the importance of performing dedicated searches for new rare tau and top decays.

    hep-phEPJC(2020)·27 citations
15. 15*

    Heavy $Z^{\prime }$ Bosons in the Secluded $U(1{)}^{\prime }$ Model at Hadron Colliders

    M. Frank (Concordia U., Canada)🇨🇦 · L. Selbuz (Ankara U., Turkey)🇹🇷 · I. Turan (METU, Turkey)🇹🇷

    We study $Z^{\prime }$ phenomenology at hadron colliders in an $U(1{)}^{\prime }$ extended MSSM. We choose a $U(1{)}^{\prime }$ model with a secluded sector, where the tension between the electroweak scale and developing a large enough mass for $Z^{\prime }$ is resolved by incorporating three additional singlet superfields into the model. We perform a detailed analysis of the production, followed by decays, including into supersymmetric particles, of a $Z^{\prime }$ boson with mass between 4 and 5.2 TeV, with particular emphasis on its possible discovery. We select three different scenarios consistent with the latest available experimental data and relic density constraints, and concentrate on final signals with two leptons, four leptons and six leptons. Including the SM background from processes with two, three or four vector bosons, we show the likelihood of observing a $Z^{\prime }$ boson is not promising for the HL-LHC at 14 TeV. While at 27 and 100 TeV, the situation is more optimistic, and we devise specific benchmark scenarios which could be observed.

    hep-phEPJC(2021)·4 citations
16. 16*

    Primordial Black-Hole Mimicker in Quadratic Gravity as Dark Matter

    Ufuk Aydemir🇨🇳

    We discuss the astrophysical and cosmological implications of having primordial thermal 2-2-hole remnants as dark matter. Thermal 2-2-holes emanate in quadratic gravity as horizonless classical solutions for ultracompact distributions of relativistic thermal gas. In contrast to a large 2-2-hole that imitates the thermodynamic behaviour of a black hole, a small 2-2-hole at late stages of evaporation behaves as a stable remnant with the mass approaching a minimal value. These remnants as all dark matter can satisfy the corresponding observational constraints provided that both the formation and remnant masses are relatively small. The parameter space for the remnant mass is probed through possible remnant mergers that would produce strong fluxes of high-energy astrophysical particles; the high-energy photon and neutrino data appear to favor towards the Planck-mass remnants, pointing to the strong-coupling scenario for the quantum theory of quadratic gravity. The formation mass, on the other hand, is constrained by the early-universe cosmology, which turns out to require 2-2-holes to evolve into the remnant state before Big Bang Nucleosynthesis.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-ph+1PoS(2020)·1 citation
17. 17*

    Study of freeze-out dynamics of strange hadrons

    Sushant K. Singh🇮🇳 · Purabi Ghosh🇮🇳 · Jajati K. Nayak🇮🇳

    We study the chemical freeze-out dynamics of strange particles ($K,\Lambda ,\Sigma$) from a homogeneous and isotropically expanding hadronic system of $\pi ,K,\rho ,N,\Lambda$ and $\Sigma$ with zero net baryon density. We use the momentum integrated Boltzmann equation and study their evolution over the bulk hadronic matter, a condition being similar to the one created at top RHIC and LHC energies. The cross-sections, which are input to the equations, are taken either from phenomenological models or parameterized by comparing against experimental data. From this microscopic calculation we find that these strange particles freeze-out near transition temperature $\approx T_c$ due to large relaxation time. The continuous cease of the inelastic processes due to gradual fall in the temperature and decrease in the number density, thus lead to early freeze out of strange hadrons $K,\Lambda$ and $\Sigma$ which happens sequentially near $T_c$. However, freeze-out of these strange species near Tc appears as a sudden and simultaneous process, which is mostly predicted by thermal model while explaining the yield of identified particles at RHIC and LHC energies.

    ↳ nucl-thhep-exhep-phnucl-exPRD(2021)·8 citations
18. 18*

    Spin tensor and pseudo-gauges: from nuclear collisions to gravitational physics

    Enrico Speranza🇩🇪 · Nora Weickgenannt🇩🇪

    The relativistic treatment of spin is a fundamental subject which has an old history. In various physical contexts it is necessary to separate the relativistic total angular momentum into an orbital and spin contribution. However, such decomposition is affected by ambiguities since one can always redefine the orbital and spin part through the so-called pseudo-gauge transformations. We analyze this problem in detail by discussing the most common choices of energy-momentum and spin tensors with an emphasis on their physical implications, and study the spin vector which is a pseudo-gauge invariant operator. We review the angular momentum decomposition as a crucial ingredient for the formulation of relativistic spin hydrodynamics and quantum kinetic theory with a focus on relativistic nuclear collisions, where spin physics has recently attracted significant attention. Furthermore, we point out the connection between pseudo-gauge transformations and the different definitions of the relativistic center of mass. Finally, we consider the Einstein-Cartan theory, an extension of conventional general relativity, which allows for a natural definition of the spin tensor.

    ↳ nucl-thhep-phhep-thEPJA(2021)·122 citations
19. 19*

    Fluctuation and Dissipation from a Deformed String/Gauge Duality Model

    Nathan G. Caldeira🇧🇷 · Eduardo Folco Capossoli🇧🇷 · Carlos A. D. Zarro🇧🇷 · Henrique Boschi-Filho🇧🇷

    Using a Lorentz invariant deformed string/gauge duality model at finite temperature we calculate the thermal fluctuation and the corresponding linear response, verifying the fluctuation-dissipation theorem. The deformed AdS${}_5$ is constructed by the insertion of an exponential factor $\exp (k/r^2)$ in the metric. We also compute the string energy and the mean square displacement in order to investigate the ballistic and diffusive regimes. Furthermore we have studied the dissipation and the linear response in the zero temperature scenario.

    ↳ hep-thhep-phPRD(2020)·11 citations
20. 20*

    Sensitivity of ${}^{229}$Th nuclear clock transition to variation of the fine-structure constant

    Pavel Fadeev🇩🇪 · Julian C. Berengut🇦🇺 · Victor V. Flambaum🇦🇺

    Peik and Tamm [Europhys. Lett. 61, 181 (2003)] proposed a nuclear clock based on the isomeric transition between the ground state and the first excited state of thorium-229. This transition was recognized as a potentially sensitive probe of possible temporal variation of the fine-structure constant, $\alpha$. The sensitivity to such a variation can be determined from measurements of the mean-square charge radius and quadrupole moment of the different isomers. However, current measurements of the quadrupole moment are yet to achieve an accuracy high enough to resolve non-zero sensitivity. Here we determine this sensitivity using existing measurements of the change in the mean-square charge radius, coupled with the ansatz of constant nuclear density. The enhancement factor for $\alpha$ variation is $K=-(0.82\pm 0.25)\times 10^4$. For the current experimental limit, $\delta \alpha /\alpha \lesssim 10^{-17}$ per year, the corresponding frequency shift is $\sim 200$ Hz per year. This shift is six orders of magnitude larger than the projected accuracy of the nuclear clock, paving the way for increased accuracy of the determination of $\delta \alpha$ and interaction strength with low-mass scalar dark matter. We verify that the constant-nuclear-density ansatz is supported by nuclear theory and propose how to verify it experimentally. We also consider a possible effect of the octupole deformation on the sensitivity to $\alpha$ variation, and calculate the effects of $\alpha$ variation in a number of Mössbauer transitions.

    ↳ physics.atom-phhep-phnucl-thPRA(2020)·65 citations
21. 21*

    Analytical Results for the Classical and Quantum Tsallis Hadron Transverse Momentum Spectra: the Zeroth Order Approximation and beyond

    Trambak Bhattacharyya🇷🇺 · Alexandru S. Parvan🇷🇺

    We derive the analytical expressions for the first and second order terms in the hadronic transverse momentum spectra obtained from the Tsallis normalized (Tsallis-1) statistics. We revisit the zeroth order quantum Tsallis distributions and obtain the corresponding analytical closed form expressions. It is observed that unlike the classical case, the analytical closed forms of the zeroth order quantum spectra do not resemble the phenomenological distributions used in the literature after $q\to q^{-1}$ substitution, where $q$ is the Tsallis entropic parameter. However, the factorization approximation increases the extent of similarity.

    ↳ nucl-thhep-exhep-phEPJA(2021)·7 citations
22. 22*

    Constraining the Charge-Sign and Rigidity-Dependence of Solar Modulation

    Ilias Cholis🇺🇸 · Dan Hooper🇺🇸 · Tim Linden🇸🇪

    Our ability to identify the sources of cosmic rays and understand how these particles propagate through the interstellar medium is hindered by the combined effects of the solar wind and its embedded magnetic field, collectively known as solar modulation. In this paper, we build upon our previous work to model and constrain the effects of solar modulation on the cosmic-ray spectrum, using data from AMS-02 and BESS Polar II collected between 2007 and 2012, during which the heliospheric magnetic field was in a state of negative polarity. Our model uses measurements of the heliospheric magnetic field and the tilt angle of the heliospheric current sheet to accurately predict the effects of solar modulation as a function of time, charge, and rigidity. By incorporating data from a period of negative polarity, we have been able to robustly observe and constrain the charge-dependent effects of solar modulation.

    ↳ astro-ph.HEastro-ph.SRhep-phphysics.space-phJCAP(2022)·30 citations
23. 23*

    Evidence for gravitational-wave dominated emission in the central engine of short GRB 200219A

    Hou-Jun Lü🇨🇳 · Yong Yuan🇨🇳 · Lin Lan🇨🇳 · Bin-Bin Zhang🇨🇳 · Jin-Hang Zou🇨🇳 · Zong-Kai Peng🇨🇳 · Jun Shen🇨🇳 · Yun-Feng Liang🇨🇳 · Xiang-Gao Wang🇨🇳 · En-Wei Liang🇨🇳

    GRB 200219A is a short gamma-ray burst (GRB) with an extended emission (EE) lasting $\sim 90$s. By analyzing data observed with the {\em Swift}/BAT and {\em Fermi}/GBM, we find that a cutoff power-law model can adequately fit the spectra of the initial short pulse with ${\mathrm{E}}_{\mathrm{p}}=1387_{-134}^{+232}$ keV. More interestingly, together with the EE component and early X-ray data, it exhibits plateau emission smoothly connected with a $\sim t^{-1}$ segment and followed by an extremely steep decay. The short GRB composed of those three segments is unique in the {\em Swift} era and is very difficult to explain with the standard internal/external shock model of a black hole central engine, but could be consistent with the prediction of a magnetar central engine from the merger of an NS binary. We suggest that the plateau emission followed by a $\sim t^{-1}$ decay phase is powered by the spin-down of a millisecond magnetar, which loses its rotation energy via GW quadrupole radiation. Then, the abrupt drop decay is caused by the magnetar collapsing into a black hole before switching to EM-dominated emission. This is the first short GRB for which the X-ray emission has such an intriguing feature powered by a magnetar via GW-dominated radiation. If this is the case, one can estimate the physical parameters of a magnetar, the GW signal powered by a magnetar and the merger-nova emission are also discussed.

    ↳ astro-ph.HEhep-phApJL(2020)·18 citations
24. 24*

    Study of a possibility of observation of hidden-bottom pentaquark resonances in bottomonium photoproduction on protons and nuclei near threshold

    E. Ya. Paryev🇷🇺

    We study the ${\rm Y}(1S)$ meson photoproduction on protons and nuclei at the near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies $E_{\gamma }$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of ${\rm Y}(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct ($\gamma p\to {\rm Y}(1S)p$) and two-step ($\gamma p\to P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$) ${\rm Y}(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary reaction $\gamma p\to {\rm Y}(1S)p$ and for branching ratios of the decays $P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$. We also calculate an analogous functions for photoproduction of ${\rm Y}(1S)$ mesons on ${}^{12}$C and ${}^{208}$Pb target nuclei in the near-threshold center-of-mass beam energy region of 9.0--11.4 GeV by considering respective incoherent direct ($\gamma N\to {\rm Y}(1S)N$) and two-step ($\gamma p\to P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$, $\gamma n\to P_b^0(11080,11125,11130)\to {\rm Y}(1S)n$) ${\rm Y}(1S)$ production processes within a nuclear spectral function approach. We show that a detailed scan of the ${\rm Y}(1S)$ total photoproduction cross section on a proton and nuclear targets in the near-threshold energy region in future high-precision experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the U.S. and China should give a definite result for or against the existence of the non-strange hidden-bottom pentaquark states $P_{bi}^{+}$ and $P_{bi}^0$ ($i=$1, 2, 3) as well as clarify their decay rates.

    ↳ nucl-thhep-phnucl-ex18 citations
25. 25*

    Why can hadronic stars convert into strange quark stars with larger radii

    Alessandro Drago🇮🇹 · Giuseppe Pagliara🇮🇹

    The total binding energy of compact stars is the sum of the gravitational binding energy $(BE{)}_g$ and the nuclear binding energy $(BE{)}_n$, the last being related to the microphysics of the interactions. While the first is positive (binding) both for hadronic stars and for strange quark stars, the second is large and negative for hadronic stars (anti-binding) and either small and negative (anti-binding) or positive (binding) for strange quark stars. A hadronic star can convert into a strange quark star with a larger radius because the consequent reduction of $(BE{)}_g$ is over-compensated by the large increase in $(BE{)}_n$. Thus, the total binding energy increases due to the conversion and the process is exothermic. Depending on the equations of state of hadronic matter and quark matter and on the baryonic mass of the star, the contrary is obviously also possible, namely the conversion of hadronic stars into strange quark stars having smaller radii, a situation more often discussed in the literature. We provide a condition that is sufficient and in most of the phenomenologically relevant cases also necessary in order to form strange quark stars with larger radii while satisfying the exothermicity request. Finally, we compare the two schemes in which quark stars are produced (one having large quark stars and the other having small quark stars) among themselves and with the third-family scenario and we discuss how present and future data can discriminate among them.

    ↳ nucl-thastro-ph.HEhep-phPRD(2020)·22 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.