Fri·Jan 29, 2021Friday·January 29, 2021

1. 01*

   RGE effects on the LFV scale from meson decays

   Marcela González🇨🇱 · Sergey Kovalenko🇨🇱 · Nicolás A. Neill🇨🇱 · Jonatan Vignatti🇨🇱

   We consider the lepton-flavor violating (LFV) lepton-quark dimension-6 operators and analyze their contributions to the LFV leptonic decays of vector, pseudoscalar, and scalar neutral mesons $M\to {\ell }_1{\ell }_2$ as well as to $\mu (\tau )\to \ell ee,\ell \gamma \gamma$ decays. These operators contribute to the purely leptonic processes via quark loop. On the basis of quark-hadron duality, we relate these loops to the appropriate meson-exchange contributions. In this way, we extract lower bounds on the individual scales of the studied LFV operators from the experimental and phenomenological limits on the leptonic decays of mesons and leptons. As a byproduct, we shall obtain new limits on the LFV leptonic decays of flavored mesons from the experimental bounds on the three-body lepton decays. We study the effects of QED and QCD radiative corrections to the LFV lepton-quark operators in question. We derive for them the one-loop matrix of the RGE evolution and examine its effect on the previously derived tree-level limits on these operators. We show that the QED corrections are particularly relevant due to operator mixing. Specifically, for some of them the limits on their individual LFV scales improve by up to 3 orders of magnitude.

   hep-phEPJC(2022)·4 citations
2. 02*

   Testing hilltop supernatural inflation with gravitational waves

   Chia-Min Lin🇨🇳

   The scale of small-field inflation cannot be constrained via primordial gravitational waves through measurement of tensor-to-scalar ratio $r$. In this study, I show that if cosmic strings are produced after symmetry breaking at the end of hilltop supernatural inflation, this small-field inflation model can be tested through the production of gravitational waves from cosmic strings. Future experiments of gravitational wave detectors will determine or further constrain the parameter space in the model.

   hep-phastro-ph.COhep-thJCAP(2021)·3 citations
3. 03*

   Top-quark pair production in association with a $W^{\pm }$ gauge boson in the POWHEG-BOX

   F. Febres Cordero🇺🇸 · M. Kraus🇺🇸 · L. Reina🇺🇸

   We present a new Monte Carlo event generator for the production of a top-quark pair in association with a $W^{\pm }$ boson at hadron colliders in the POWHEG-BOX framework. We consider the next-to-leading-order QCD corrections to the $pp\to t\bar{t}{W}^{\pm }$ cross section, corresponding to the $\mathcal{O}({\alpha }_s^3\alpha )$ and $\mathcal{O}({\alpha }_s{\alpha }^3)$ terms in the perturbative expansion of the parton-level cross section, and model the decays of $W$ and top quarks at leading order retaining spin correlations. The fixed-order QCD calculation is further interfaced with the Pythia8 parton-shower event generator via the POWHEG method as implemented in the POWHEG-BOX. The corresponding code is now part of the public repository of the POWHEG-BOX. We perform a comparison of different event generators for both the case of inclusive production and the case of the two same-sign leptons signature at the Large Hadron Collider operating at a center-of-mass energy of $13$ TeV. We investigate theoretical uncertainties in the modelling of the fiducial volume stemming from missing higher-order corrections, the different parton shower matching schemes, and the modelling of decays. We find that the subleading contribution at $\mathcal{O}({\alpha }_s{\alpha }^3)$ is particularly sensitive to differences in the matching scheme and higher-order parton shower effects. We observe that in particular jet observables can differ quite visibly although these differences play only a subordinate role in the description of physical observables once all contributions are combined.

   hep-phhep-exPRD(2021)·52 citations
4. 04*

   Importance of the heavy-quarks longitudinal structure function measurements at future circular collider energies

   G.R.Boroun🇮🇷

   In this article, we consider the ratio of structure functions for heavy quark pair production at low values of $x$. The importance of this ratio for charm and beauty pair production is examined according to the Hadron Electron Ring Accelerator (HERA) data. The behavior of these ratios considers due to the hard-pomeron behavior of the gluon distribution function. The results are in good agreement with respect to the HERA data. Expanding this data to the range of new energies underscore the importance of these measurements for heavy quarks. The ratio of charm and beauty structure functions at the proposed Large Hadron electron Collider (LHeC) is considered as a function of invariant center-of-mass energy. For top pair production this ratio is extracted with known kinematics of the LHeC and Future Circular Collider electron-hadron (FCC-eh) colliders. Comparison of the results obtained for the ratio of top structure functions in LHeC and FCC-eh are proportional to the specified inelasticity $y$ range.

   hep-phCPC(2021)·5 citations
5. 05*

   Influence of gluon behavior on heavy-quark pair production

   G.R.Boroun🇮🇷 · B.Rezaei

   We check the impact of the gluon distribution due to the number of active flavor employed in the calculation of heavy-quark deep-inelastic scattering (DIS) electro-production on the reduced cross section and structure functions determined in the leading order (LO) and next-to-leading order (NLO) quantum chromodynamics (QCD) analysis using the Hadron Electron Ring Accelerator (HERA) combined data. The charm and beauty structure functions are determined and compared with the HERA combined data. The results are in good agreement with respect to the experimental data. We also compare the obtained charm and bottom structure functions with the results from CTEQ6.6 [Phys.Rev.D{\bf78}, 013004(2008)] and NNPDF3.1[Eur.Phys.J.C{\bf77}, 663(2017)] parameterization models. The effect of gluon density on these calculations depends on the number of active flavor at asymptotical values of the momentum transfer $Q^2$. Also, in the HERA kinematic range, the ratio of $F_2^{c\overline{c}}/F_2$ and $F_2^{b\overline{b}}/F_2$ are obtained. These results and comparison with the HERA combined data demonstrate that the suggested method can be applied in analysis of new colliders.

   hep-phEPL(2021)·4 citations
6. 06*

   On the four-quark operator matrix elements for the lifetime of ${\Lambda }_b$

   Zhen-Xing Zhao🇨🇳 · Xiao-Yu Sun🇨🇳 · Fu-Wei Zhang🇨🇳 · Zhi-Peng Xing🇨🇳

   Heavy quark expansion can nicely explain the lifetime of ${\Lambda }_b$. However, there still exist sizable uncertainties from the four-quark operator matrix elements of ${\Lambda }_b$ in $1/m_b^3$ corrections, which describe the spectator effects. In this work, these four-quark operator matrix elements are investigated using full QCD sum rules for the first time. At the QCD level, contributions from up to dimension-6 four-quark operators are considered. Our method of calculating high-dimensional operator matrix elements is promising to be used to resolve the ${\Omega }_c$ lifetime puzzle.

   hep-phEPJC(2024)·8 citations
7. 07*

   CP-Symmetry in Scattering of Neutrinos from Nuclei

   R.B. Begzhanov🇺🇿 · R.S. Sharafiddinov🇺🇿

   The elastic scattering of longitudinal and transversal neutrinos on a spinless nucleus have been discussed taking into account the charge, magnetic, anapole and electric dipole moments of fermions and their weak neutral currents. Compound structure of the neutrino interaction cross section with nuclei have been defined. Invariance of the considered process concerning the C - and P-operations have been investigated in the polarization type dependence.

   hep-phnucl-thBull.Russ.Acad.Sci.Phys.(2000)·0 citations
8. 08*

   New Developments in Relativistic Fluid Dynamics with spin

   Samapan Bhadury🇮🇳 · Jitesh Bhatt🇮🇳 · Amaresh Jaiswal🇮🇳 · Avdhesh Kumar🇮🇳

   In this work, we briefly review the progress made in the formulation of hydrodynamics with spin with emphasis on the application to the relativistic heavy-ion collisions. In particular, we discuss the formulation of hydrodynamics with spin for perfect-fluid and the first order viscous corrections with some discussion on the calculation of spin kinetic coefficients. Finally, we apply relativistic hydrodynamics with spin to the relativistic heavy-ion collisions to calculate the spin polarization of $\Lambda$-particles.

   hep-phnucl-thEur.Phys.J.ST(2021)·50 citations
9. 09*

   Phase diagram for strongly interacting matter in the presence of a magnetic field using the Polyakov-Nambu-Jona-Lasinio model with magnetic field dependent coupling strengths

   João Moreira🇵🇹 · Pedro Costa🇵🇹 · Tulio E. Restrepo🇧🇷

   We study the phase diagram for strongly interacting matter using the 't Hooft determinant extended Nambu--Jona-Lasinio model with a Polyakov loop in the light and strange quark sectors (\emph{up}, \emph{down} and \emph{strange}) focusing on the effect of a magnetic field dependence of the coupling strengths of these interactions. This dependence was obtained so as to reproduce recent lattice QCD results for the magnetic field dependence of the quarks dynamical masses. A finite magnetic field is known to induce several additional first-order phase transition lines with the respective Critical End Points (CEP) in the temperature-quark chemical potential phase diagram when compared to the zero magnetic field case. A study of the magnetic field dependence in the range $eB=0-0.6{\mathrm{GeV}}^2$ of the location of these CEPs reveals that the initial one as well as several of the new ones only survive up to a critical magnetic field. Only two remain in the upper limit of the studied magnetic field strength. A comparison of the results obtained with versions of the model with and without Polyakov loop is also done. We also found that the inclusion of the magnetic field dependence on the coupling strengths, while not changing the qualitative features of the phase diagram, affects the location of these CEPs. The comparison of results with and without a regularization cutoff in the medium part of the integrals does not show a significant change.

   hep-phEPJA(2021)·14 citations
10. 10*

    Rescattering mechanism of weak decays of double-charm baryons

    Jia-Jie Han🇨🇳 · Hua-Yu Jiang🇨🇳 · Wei Liu🇨🇳 · Zhen-Jun Xiao🇨🇳 · Fu-Sheng Yu🇨🇳

    The doubly charmed baryon ${\Xi }_{cc}^{++}$ was recently observed by LHCb via the decay processes of ${\Xi }_{cc}^{++}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+}$ and ${\Xi }_c^{+}{\pi }^{+}$. These discovery channels were successfully predicted in the framework that the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects. In this paper, we illustrate the above framework in details by systematic studies on the two-body baryonic decays ${\mathcal{B}}_{cc}\to {\mathcal{B}}_{c}P$ involving the doubly charmed baryons ${\mathcal{B}}_{cc}=({\Xi }_{cc}^{++},{\Xi }_{cc}^{+},{\Omega }_{cc}^{+})$, the singly charmed baryons ${\mathcal{B}}_c=({\mathcal{B}}_{\bar{3}},{\mathcal{B}}_6)$ and the light pseudoscalar mesons $P=(\pi ,K,{\eta }_{1,8})$.

    hep-phhep-exCPC(2021)·42 citations
11. 11*

    Heavy quark expansion of ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ form factors beyond leading order

    Marzia Bordone🇩🇪

    I review the parametrisation of the full set of ${\Lambda }_b\to {\Lambda }^{\ast }(1520)$ form factors in the framework of Heavy Quark Expansion, including next-to-leading-order $\mathcal{O}({\alpha }_s)$ and, for the first time, next-to-leading-power $\mathcal{O}(1/m_b)$ corrections. The unknown hadronic parameters are obtained by performing a fit to recent lattice QCD calculations. I investigate the compatibility of the Heavy Quark Expansion and the current lattice data, finding tension between these two approaches in the case of tensor and pseudo-tensor form factors, whose origin could come from an underestimation of the current lattice QCD uncertainties and higher order terms in the Heavy Quark Expansion.

    hep-phSymmetry(2021)·15 citations
12. 12*

    Precise limits on the charge-$2/3$ $U_1$ vector leptoquark

    Arvind Bhaskar🇮🇳 · Diganta Das🇮🇳 · Tanumoy Mandal🇮🇳 · Subhadip Mitra🇮🇳 · Cyrin Neeraj🇮🇳

    The $U_1$ leptoquark is known to be a suitable candidate for explaining the semileptonic $B$-decay anomalies. We derive precise limits on its parameter space relevant for the anomalies from the current LHC high-$p_{\mathrm{T}}$ dilepton data. We consider an exhaustive list of possible $B$-anomalies-motivated simple scenarios with one or two new couplings that can also be used as templates for obtaining bounds on more complicated scenarios. To obtain precise limits, we systematically consider all possible $U_1$ production processes that can contribute to the dilepton searches, including the resonant pair and single productions, nonresonant $t$-channel $U_1$ exchange, as well as its large interference with the Standard Model background. We demonstrate how the inclusion of resonant production contributions in the dilepton signal can lead to appreciably improved exclusion limits. We point out new search channels of $U_1$ that can act as unique tests of the flavour-motivated models. The template scenarios can also be used for future $U_1$ searches at the LHC. We compare the LHC limits with other relevant flavour bounds and find that a TeV-scale $U_1$ can accommodate both $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies while satisfying all the bounds.

    hep-phhep-exPRD(2021)·50 citations
13. 13*

    Top quark contribution to two-loop helicity amplitudes for $Z$ boson pair production in gluon fusion

    Christian Brønnum-Hansen🇩🇪 · Chen-Yu Wang🇩🇪

    We compute the top quark contribution to the two-loop amplitude for on-shell $Z$ boson pair production in gluon fusion, $gg\to ZZ$. Exact dependence on the top quark mass is retained. For each phase space point the integral reduction is performed numerically and the master integrals are evaluated using the auxiliary mass flow method, allowing fast computation of the amplitude with very high precision.

    hep-phPoS(2022)·32 citations
14. 14*

    Classical resummation and breakdown of strong-field QED

    T. Heinzl🇬🇧 · A. Ilderton🇬🇧 · B. King🇬🇧

    QED perturbation theory has been conjectured to break down in sufficiently strong backgrounds, obstructing the analysis of strong-field physics. We show that the breakdown occurs even in classical electrodynamics, at lower field strengths than previously considered, and that it may be cured by resummation. As a consequence, an analogous resummation is required in QED. A detailed investigation shows, for a range of observables, that unitarity removes diagrams previously believed to be responsible for the breakdown of QED perturbation theory.

    hep-phPRL(2021)·43 citations
15. 15*

    $t-b-\tau$ Yukawa Unification in Non-Holomorphic MSSM

    Yaşar Hiçyılmaz🇬🇧

    We show that in the CMSSM with the non-holomorphic soft SUSY breaking terms, the Yukawa coupling unification of the third family fermions at the GUT scale, called $t-b-\tau$ Yukawa unification (YU), is possible under the recent collider and Dark Matter results. The YU parameter can also be found $R_{tb\tau }\approx 1$, called perfect unification. We find that the squark masses exceed 3 TeV while the stau can be considerably lighter. In the case of YU, the $\tan \beta$ is in the interval $[46,55]$. We obtain bino-like dark matter (DM) of mass in the range of $0.6$ TeV $\lesssim m_{{\chi }_1^0}\lesssim 1.3$ TeV where the recent Dark Matter direct detection limits are also satisfied. We also identify A-resonance solutions which reduce the relic abundance of LSP neutralino down to the ranges compatible with the current Planck measurements.

    hep-phJHEP(2021)·6 citations
16. 16*

    Probing bino NLSP at lepton colliders

    Junmou Chen🇨🇳 · Chengcheng Han🇨🇳 · Jin Min Yang🇨🇳 · Mengchao Zhang🇨🇳

    We consider a scenario where light bino is the next-to-lightest supersymmetric particle (NLSP) and gravitino/axino is the lightest superysmmetric particle (LSP). For a bino mass less than or around hundred GeV, it can be pair produced at the future lepton colliders through $t-$channel slepton exchange, subsequently decaying into a gravitino/axino plus a photon. We study the prospects to look for such binos at the future colliders and find that a bino mass around 100 GeV can be probed at the $2\sigma$ ($5\sigma$) level for a slepton below 2 TeV (1.5 TeV) with a luminosity 3 $a{b}^{-1}$. For a bino mass around 10 GeV, a slepton mass less than 4 TeV (3 TeV) can be probed at the $2\sigma$ ($5\sigma$) level, which is much beyond the reach of the LHC for direct slepton searches.

    hep-phPRD(2021)·9 citations
17. 17*

    A modified in-medium evolution equation with color coherence

    João Barata🇪🇸 · Fabio Domínguez🇪🇸 · Carlos Salgado🇪🇸 · Víctor Vila🇫🇷

    QCD jets produced in heavy-ion collisions at LHC or RHIC energies partially evolve inside the produced hot and dense quark gluon plasma, offering unique opportunities to study QCD splitting processes in different backgrounds. Induced (modified) splittings are expected to be the most relevant mechanism driving the modifications of in-medium jets compared to vacuum jets for a wide sets of observables. Although color coherence among different emitters has been identified as an essential mechanism in studies of the {\it QCD antenna radiation}, it is usually neglected in the multi-gluon medium-induced cascade. This independent gluon emission approximation can be analytically proved to be valid in the limit of very large media, but corrections or modifications to it have not been computed before in the context of the evolution (or rate) equation describing the gluon cascade. We propose a modified evolution equation that includes corrections due to the interference of subsequent emitters. In order to do so, we first compute a modified splitting kernel following the usual procedure of factorizing it from the subsequent Brownian motion. The calculation is performed in the two-gluon configuration with no overlapping formation times, that is expected to provide the first correction to the completely independent picture.

    hep-phJHEP(2021)·32 citations
18. 18*

    Linkage of Dirac Neutrinos to Dark U(1) Gauge Symmetry

    Ernest Ma (UC Riverside)🇺🇸

    It is shown how a mechanism which allows naturally small Dirac neutrino masses is linked to the existence of dark matter through an anomaly-free U(1) gauge symmetry of fermion singlets.

    hep-phPLB(2021)·16 citations
19. 19*

    Fully Geant4 compatible package for the simulation of Dark Matter in fixed target experiments

    M. Bondi🇮🇹 · A. Celentano🇮🇹 · R. R. Dusaev🇷🇺 · D. V. Kirpichnikov🇷🇺 · M. M. Kirsanov🇷🇺 · N. V. Krasnikov🇷🇺 · L. Marsicano🇮🇹 · D. Shchukin

    We present the package for the simulation of DM (Dark Matter) particles in fixed target experiments. The most convenient way of this simulation (and the only possible way in the case of beam-dump) is to simulate it in the framework of the program for tracing particles in the experimental setup. One of the most popular such programs is Geant4. Specifically, the package includes the processes of DM particles production via electron and muon bremsstrahlung off nuclei, resonant in-flight positron annihilation on atomic electrons and gamma to ALP (axion-like particles) conversion on nuclei. Four types of DM mediator particles are considered: vector, scalar, pseudoscalar and axial vector. In particular, for bremsstrahlung the total cross sections are calculated at exact tree level (ETL). The code handles both the case of invisible DM mediator decay and of visible decay into $e^{+}{e}^{-}$ (or into $\gamma \gamma$ in the case of ALP). The software consists of a collection of different classes, inheriting from the Geant4 framework classes, thus the expected use of this package is to include it in a Geant4-based code for the simulation of particles propagation and interaction in the detector. As an example of its usage, we discuss the results obtained from the simulation of a typical active beam-dump experiment, considering $5\times 10^{12}$ 100 GeV electrons impinging on a lead/plastic scintillator active thick target, showing the expected sensitivity for the four types of DM mediator particles mentioned above.

    hep-phComput.Phys.Commun.(2021)·46 citations
20. 20*

    Modern status of heavy quark sum rules in QCD

    Stephan Narison (LUPM-CNRS/Univ Montpellier, FR and iHEPMAD-Univ. Antananarivo, MG)🇫🇷

    We briefly report the modern status of heavy quark sum rules (HQSR) based on stability criteria by emphasizing the recent progresses for determining the QCD parameters (alpha_s, m_{c,b} and gluon condensates)where their correlations have been taken into account. The results: alpha_s(M_Z)=0.1181(16)(3), m_c(m_c)=1286(16) MeV, m_b(m_b)=4202(7) MeV,<alpha_s G^2> = (6.49+-0.35)10^-2 GeV^4, < g^3 G^3 >= (8.2+-1.0) GeV^2 <alpha_s G^2> and the ones from recent light quark sum rules are summarized in Table 2. One can notice that the SVZ value of <alpha_s G^2> has been underestimated by a factor 1.6, <g^3 G^3> is much bigger than the instanton model estimate, while the four-quark condensate which mixes under renormalization is incompatible with the vacuum saturation which is phenomenologically violated by a factor (2~4). The uses of HQSR for molecules and tetraquarks states are commented.

    hep-phhep-exhep-lathep-th+1Nucl.Part.Phys.Proc.(2021)·8 citations
21. 21*

    Wave Dark Matter

    Lam Hui (Columbia University)🇺🇸

    We review the physics and phenomenology of wave dark matter: a bosonic dark matter candidate lighter than about 30 eV. Such particles have a de Broglie wavelength exceeding the average inter-particle separation in a galaxy like the Milky Way, and are well described as classical waves. We outline the particle physics motivations for them, including the QCD axion and ultra-light axion-like-particles such as fuzzy dark matter. The wave nature of the dark matter implies a rich phenomenology: (1) Wave interference leads to order unity density fluctuations on de Broglie scale. A manifestation is vortices where the density vanishes and around which the velocity circulates. There is one vortex ring per de Broglie volume on average. (2) For sufficiently low masses, soliton condensation occurs at centers of halos. The soliton oscillates and random walks, another manifestation of wave interference. The halo/subhalo abundance is suppressed at small masses, but the precise prediction from numerical wave simulations remains to be determined. (3) For ultra-light ~$10^{-22}$ eV dark matter, the wave interference substructures can be probed by tidal streams/gravitational lensing. The signal can be distinguished from that due to subhalos by the dependence on stream orbital radius/image separation. (4) Axion detection experiments are sensitive to interference substructures for moderately light masses. The stochastic nature of the waves affects the interpretation of experiments and motivates the measurement of correlation functions. Current constraints and open questions, covering detection experiments and cosmological/galactic/black-hole observations, are discussed.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1Ann.Rev.Astron.Astrophys.(2021)·563 citations
22. 22*

    Cosmological test of an extended quintessence model

    Gong Cheng🇨🇳 · Fengquan Wu🇨🇳 · Xuelei Chen🇨🇳

    We investigate the cosmological observational test of the extended quintessence model, i.e. a scalar-tensor gravity model with a scalar field potential serving as dark energy, by using the Planck 2018 cosmic microwave background (CMB) data, together with the baryon acoustic oscillations (BAO) and redshift-space distortion (RSD) data. As an example, we consider the model with a Brans-Dicke kinetic term $\frac{\omega (\varphi )}{\varphi }{\varphi }_{;\mu }{\varphi }^{;\mu }$ and a quadratic scalar potential $V(\varphi )=A+B(\varphi -{\varphi }_0)+\frac{C}{2}(\varphi -{\varphi }_0{)}^2$, which reduces to general relativity (GR) in the limit $\omega (\varphi )\to \infty$, and the cosmological constant in the limit $B=C=0$. In such a model the scalar field typically rolls down the potential and oscillates around the minimum of $V(\varphi )$. We find that the model parameter estimate for the CMB+BAO+RSD data set is given by $\lg \alpha =-3.6_{-0.54}^{+0.66}(68\%)$, corresponding to $3.8\times 10^5<{\omega }_0<9.5\times 10^7(68\%)$, and $\lg C=4.9\pm 1.4(68\%)$. However, the GR $\Lambda$CDM model can fit the data almost as good as this extended quintessence model, and is favored by the Akaike information criterion (AIC). The variation of the gravitational constant since the epoch of Recombination is constrained to be $0.97<G_{\mathrm{rec}}/G_0<1.03(1\sigma )$. In light of recent report that the CMB data favors a closed universe, we consider the case with non-flat geometry in our fit, and find that the mean value of ${\Omega }_k$ shifts a little bit from $-0.049$ to $-0.036$, and the parameters in our model are not degenerate with ${\Omega }_k$.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·4 citations
23. 23*

    Forecast for cosmological parameter estimation with gravitational-wave standard sirens from the LISA-Taiji network

    Ling-Feng Wang🇨🇳 · Shang-Jie Jin🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    LISA and Taiji are expected to form a space-based gravitational-wave (GW) detection network in the future. In this work, we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network. We simulate the standard siren data based on a scenario with configuration angle of $40^{\circ }$ between LISA and Taiji. Three models for the population of massive black hole binary (MBHB), i.e., pop III, Q3d, and Q3nod, are considered to predict the events of MBHB mergers. We find that, based on the LISA-Taiji network, the number of electromagnetic (EM) counterparts detected is almost doubled compared with the case of single Taiji mission. Therefore, the LISA-Taiji network's standard siren observation could provide much tighter constraints on cosmological parameters. For example, solely using the standard sirens from the LISA-Taiji network, the constraint precision of $H_0$ could reach $1.3\%$. Moreover, combined with the CMB data, the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy, e.g., the constraint precision of $w$ reaches about $4\%$, which is comparable with the result of CMB+BAO+SN. It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future.

    ↳ gr-qcastro-ph.COhep-phSCPMA(2022)·86 citations
24. 24*

    Celestial-Body Focused Dark Matter Annihilation Throughout the Galaxy

    Rebecca K.Leane🇺🇸 · Tim Linden🇸🇪 · Payel Mukhopadhyay🇺🇸 · Natalia Toro🇺🇸

    Indirect detection experiments typically measure the flux of annihilating dark matter (DM) particles propagating freely through galactic halos. We consider a new scenario where celestial bodies "focus" DM annihilation events, increasing the efficiency of halo annihilation. In this setup, DM is first captured by celestial bodies, such as neutron stars or brown dwarfs, and then annihilates within them. If DM annihilates to sufficiently long-lived particles, they can escape and subsequently decay into detectable radiation. This produces a distinctive annihilation morphology, which scales as the product of the DM and celestial body densities, rather than as DM density squared. We show that this signal can dominate over the halo annihilation rate in $\gamma$-ray observations in both the Milky Way Galactic center and globular clusters. We use \textit{Fermi} and H.E.S.S. data to constrain the DM-nucleon scattering cross section, setting powerful new limits down to $\sim 10^{-39}$cm${}^2$ for sub-GeV DM using brown dwarfs, which is up to nine orders of magnitude stronger than existing limits. We demonstrate that neutron stars can set limits for TeV-scale DM down to about $10^{-47}$cm${}^2$.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2021)·93 citations
25. 25*

    Dispersive analysis of low energy ${\gamma }^{\ast }N\to \pi N$ process

    Xiong-Hui Cao (Peking U. and Peking U., SKLNPT)🇨🇳 · Yao Ma (Peking U. and Peking U., SKLNPT)🇨🇳 · Han-Qing Zheng (Peking U. and Peking U., SKLNPT and CICQM, Beijing)🇨🇳

    We use a dispersion representation based on unitarity and analyticity to study the low energy ${\gamma }^{\ast }N\to \pi N$ process in the $S_{11}$ channel. Final state interactions among the $\pi N$ system are critical to this analysis. The left-hand part of the partial wave amplitude is imported from $\mathcal{O}(p^2)$ chiral perturbation theory result. On the right-hand part, the final state interaction is calculated through Omnès formula in $S$ wave. It is found that a good numerical fit can be achieved with only one subtraction parameter, and the eletroproduction experimental data of multipole amplitudes $E_{0+},S_{0+}$ in the energy region below $\Delta (1232)$ are well described when the photon virtuality $Q^2\le 0.1{\mathrm{GeV}}^2$.

    ↳ nucl-thhep-phPRD(2021)·9 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.