Thu·Feb 4, 2021Thursday·February 4, 2021

1. 01*

   Implications for First-Order Cosmological Phase Transitions from the Third LIGO-Virgo Observing Run

   Alba Romero🇪🇸 · Katarina Martinovic🇬🇧 · Thomas A. Callister🇺🇸 · Huai-Ke Guo🇺🇸 · Mario Martínez🇪🇸 · Mairi Sakellariadou🇬🇧 · Feng-Wei Yang🇺🇸 · Yue Zhao🇺🇸

   We place constraints on the normalized energy density in gravitational waves from first-order strong phase transitions using data from Advanced LIGO and Virgo's first, second and third observing runs. First, adopting a broken power law model, we place $95\%$ confidence level upper limits simultaneously on the gravitational-wave energy density at 25 Hz from unresolved compact binary mergers, ${\Omega }_{\mathrm{CBC}}<6.1\times 10^{-9}$, and strong first-order phase transitions, ${\Omega }_{\mathrm{BPL}}<4.4\times 10^{-9}$. The inclusion of the former is necessary since we expect this astrophysical signal to be the foreground of any detected spectrum. We then consider two more complex phenomenological models, limiting at 25 Hz the gravitational-wave background due to bubble collisions to ${\Omega }_{\mathrm{pt}}<5.0\times 10^{-9}$ and the background due to sound waves to ${\Omega }_{\mathrm{pt}}<5.8\times 10^{-9}$ at $95\%$ confidence level for phase transitions occurring at temperatures above $10^8$GeV.

   hep-phgr-qcPRL(2021)·80 citations
2. 02*

   Open Quantum Systems for Quarkonia

   Xiaojun Yao🇺🇸

   I review recent applications of the open quantum system framework in the understanding of quarkonium suppression in heavy-ion collisions, which has been used as a probe of the quark-gluon plasma for decades. The derivation of the Lindblad equations for quarkonium in both the quantum Brownian motion and the quantum optical limits and their semiclassical counterparts is explained. The hierarchy of time scales assumed in the derivation is justified from the separation of energy scales in nonrelativistic effective field theories of QCD. Physical implications of the open quantum system approach are also discussed. Finally, I list some open questions for future studies.

   hep-phhep-exnucl-thInt.J.Mod.Phys.A(2021)·100 citations
3. 03*

   Measuring solar neutrinos over Gigayear timescales with Paleo Detectors

   Natalia Tapia Arellano🇺🇸 · Shunsaku Horiuchi🇺🇸

   Measuring the solar neutrino flux over gigayear timescales could provide a new window to inform the Solar Standard Model as well as studies of the Earth's long-term climate. We demonstrate the feasibility of measuring the time-evolution of the ${}^8$B solar neutrino flux over gigayear timescales using paleo detectors, naturally occurring minerals which record neutrino-induced recoil tracks over geological times. We explore suitable minerals and identify track lengths of 15--30 nm to be a practical window to detect the ${}^8$B solar neutrino flux. A collection of ultra-radiopure minerals of different ages, each some 0.1 kg by mass, can be used to probe the rise of the ${}^8$B solar neutrino flux over the recent gigayear of the Sun's evolution. We also show that models of the solar abundance problem can be distinguished based on the time-integrated tracks induced by the ${}^8$B solar neutrino flux.

   hep-phastro-ph.HEastro-ph.IMastro-ph.SR+1PRD(2021)·20 citations
4. 04*

   Insights into the Emergence of Mass from Studies of Pion and Kaon Structure

   Craig D. Roberts🇨🇳 · David G. Richards🇺🇸 · Tanja Horn🇺🇸 · Lei Chang🇨🇳

   There are two mass generating mechanisms in the standard model of particle physics (SM). One is related to the Higgs boson and fairly well understood. The other is embedded in quantum chromodynamics (QCD), the SM's strong interaction piece; and although responsible for emergence of the roughly 1 GeV mass scale that characterises the proton and hence all observable matter, the source and impacts of this emergent hadronic mass (EHM) remain puzzling. As bound states seeded by a valence-quark and -antiquark, pseudoscalar mesons present a simpler problem in quantum field theory than that associated with the nucleon. Consequently, there is a large array of robust predictions for pion and kaon properties whose empirical validation will provide a clear window onto many effects of both mass generating mechanisms and the constructive interference between them. This has now become significant because new-era experimental facilities, in operation, construction, or planning, are capable of conducting such tests and thereby contributing greatly to resolving the puzzles of EHM. These aspects of experiment, phenomenology, and theory, along with contemporary successes and challenges, are sketched herein, simultaneously highlighting the potential gains that can accrue from a coherent effort aimed at finally reaching an understanding of the character and structure of Nature's Nambu-Goldstone modes.

   hep-phhep-exhep-latnucl-ex+1PPNP(2021)·214 citations
5. 05*

   Anomalies and parities for quintessential and ultra-light axions

   Jihn E. Kim🇰🇷

   We discuss the energy scales of the explicit breaking terms of the global symmetries \USW~ needed for the quinessential axion (QA) and the ultra-light axion (ULA). The appropriate scale of QA is about $10^8$ GeV.

   hep-phastro-ph.COhep-thPLB(2021)·3 citations
6. 06*

   Two-loop leading colour QCD corrections to $q\bar{q}\to \gamma \gamma g$ and $qg\to \gamma \gamma q$

   Bakul Agarwal🇺🇸 · Federico Buccioni🇬🇧 · Andreas von Manteuffel🇺🇸 · Lorenzo Tancredi🇬🇧

   We present the leading colour and light fermionic planar two-loop corrections for the production of two photons and a jet in the quark-antiquark and quark-gluon channels. In particular, we compute the interference of the two-loop amplitudes with the corresponding tree level ones, summed over colours and polarisations. Our calculation uses the latest advancements in the algorithms for integration-by-parts reduction and multivariate partial fraction decomposition to produce compact and easy-to-use results. We have implemented our results in an efficient C++ numerical code. We also provide their analytic expressions in Mathematica format.

   hep-phhep-thJHEP(2021)·70 citations
7. 07*

   Revisiting the production of $J/\psi +{\eta }_c$ via the $e^{+}{e}^{-}$ annihilation within the QCD light-cone sum rules

   Long Zeng🇨🇳 · Hai-Bing Fu🇨🇳 · Dan-Dan Hu🇨🇳 · Ling-Li Chen🇨🇳 · Wei Cheng🇨🇳 · Xing-Gang Wu🇨🇳

   We make a detailed study on the typical production channel of double charmoniums, $e^{+}{e}^{-}\to J/\psi +{\eta }_c$, at the center-of-mass collision energy $\sqrt{s}=10.58$ GeV. The key component of the process is the form factor $F_{\mathrm{VP}}(q^2)$, which has been calculated within the QCD light-cone sum rules (LCSR). To improve the accuracy of the derived LCSR, we keep the $J/\psi$ light-cone distribution amplitude up to twist-4 accuracy. Total cross sections for $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at three typical factorization scales are $\sigma {|}_{{\mu }_s}=22.53_{-3.49}^{+3.46}\mathrm{fb}$, $\sigma {|}_{{\mu }_k}=21.98_{-3.38}^{+3.35}\mathrm{fb}$ and $\sigma {|}_{{\mu }_0}=21.74_{-3.33}^{+3.29}\mathrm{fb}$, respectively. The factorization scale dependence is small, and those predictions are consistent with the BABAR and Belle measurements within errors.

   hep-phPRD(2021)·5 citations
8. 08*

   Generation of quasi-monoenergetic positron beams in chirped laser fields

   Suo Tang🇨🇳

   High energy photons can decay to electron-positron pairs via the nonlinear Breit-Wheeler process when colliding with an intense laser pulse. The energy spectrum of the produced particles is broadened because of the variation of their effective mass in the course of the laser pulse. Applying a suitable chirp to the laser pulse can narrow the energy distribution of the generated electrons and positrons. We present a scenario where a high-energy electron beam is collided with a chirped laser pulse to generate a beam of quasi-monoenergetic $\gamma$-photons, which then decay in a second chirped, UV pulse to produce a quasi-monoenergetic source of high-energy electrons and positrons.

   hep-phPRA(2021)·8 citations
9. 09*

   Importance of fermion loops $W^{+}{W}^{-}$ in elastic scattering

   Antonio Dobado🇪🇸 · Carlos Quezada-Calonge🇪🇸 · Juan José Sanz-Cillero🇪🇸

   We test the assumption that fermion-loop corrections to high energy $W^{+}{W}^{-}$ scattering are negligible when compared to the boson-loop ones. Indeed, we find that, if the couplings of the interactions deviate from their Standard Model values, fermion-loop corrections can in fact become as important or even greater than boson-loop corrections for some particular regions of the parameter space, and both types of loops should be taken into account. Some preliminary results are shown.

   hep-phNucl.Part.Phys.Proc.(2021)·3 citations
10. 10*

    Search for the limits on anomalous neutral triple gauge couplings via $ZZ$ production in the $\ell \ell \nu \nu$ channel at FCC-hh

    Ali Yilmaz🇹🇷

    This paper presents the projections on the anomalous neutral triple gauge couplings ($aNTGC$) via $pp\to ZZ$ production in the 2$\ell$2$\nu$ final state at a 100 TeV proton-proton collider, \verb"FCC-hh". %100 TeV center of mass energy of The realistic \verb"FCC-hh" detector environments and its effects taken into account in the analysis. The study is carried out in the mode where one Z boson decays into a pair of same-flavor, opposite-sign leptons (electrons or muons) and the other one decays to the two neutrinos. The new bounds on the charge-parity (CP)-conserving couplings $C_{\tilde{B}W}/{\Lambda }^4$ and CP-violating couplings $C_{WW}/{\Lambda }^4$, $C_{BW}/{\Lambda }^4$ and $C_{BB}/{\Lambda }^4$ achived at 95\% Confidence Level (C.L.) using the transverse momentum of the dilepton system ($p_T^{\ell \ell }$) are $[-0.042,+0.042]$, $[-0.050,+0.050]$, $[-0.050,+0.050]$, and $[-0.048,+0.048]$ in units of TeV${}^{-4}$, respectively.

    hep-phNPB(2021)·12 citations
11. 11*

    Magnetic dipole moments of the hidden-charm pentaquark states: $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$

    Ulaş Özdem🇹🇷

    In this work, we employ the light-cone QCD sum rule to calculate the magnetic dipole moments of the $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$ pentaquark states by considering them as the diquark-diquark-antiquark and molecular pictures with quantum numbers $J^P={\frac{3}{2}}^{-}$, $J^P={\frac{1}{2}}^{-}$ and $J^P={\frac{1}{2}}^{-}$, respectively. In the analyses, we use the diquark-diquark-antiquark and molecular form of interpolating currents, and photon distribution amplitudes to obtain the magnetic dipole moment of pentaquark states. Theoretical examinations on magnetic dipole moments of the hidden-charm pentaquark states, are essential as their results can help us better figure out their substructure and the dynamics of the QCD as the theory of the strong interaction. As a by product, we extract the electric quadrupole and magnetic octupole moments of the $P_c(4440)$ pentaquark. These values show a non-spherical charge distribution.

    hep-phhep-exhep-latEPJC(2021)·64 citations
12. 12*

    Self-consistent light-front quark model analysis of $B\to D\ell {\nu }_{\ell }$ transition form factors

    Ho-Meoyng Choi (Kyungpook National University)🇰🇷

    We investigate the transition form factors $f_{+}(q^2)$ and $f_{-}(q^2)$ [or $f_0(q^2)$] for the exclusive semileptonic $B\to D\ell {\nu }_{\ell }$ $(\ell =e,\mu ,\tau )$ decays in the standard light-front quark model (LFQM) based on the LF quantization. The common belief is that while $f_{+}(q^2)$ can be obtained without involving any treacherous contributions such as the zero mode and the instantaneous contribution, $f_{-}(q^2)$ receives those treacherous contributions since it involves at least two components of the current, e.g. $(J^{+},J^{-})$ or $(J^{+},{\mathbf{J}}_{\perp })$. Contrary to the common belief, we show in the Drell-Yan ($q^{+}=0$) frame that $f_{-}(q^2)$ obtained from $(J^{+},J^{-})$ gives identical result to $f_{-}(q^2)$ obtained from $(J^{+},{\mathbf{J}}_{\perp })$ without involving such treacherous contributions in the standard LFQM. In our numerical calculations, we obtain the form factors and branching ratios for $B\to D\ell {\nu }_{\ell }$ $(\ell =e,\mu ,\tau )$ and compare with the experimental data as well as other theoretical model predictions. Our results for $\mathrm{Br}(B\to D\ell {\nu }_{\ell })$ show reasonable agreement with the experimental data except for the semitauonic $B^0\to D^{-}\tau {\nu }_{\tau }$ decay. The ratio $\mathcal{R}(D)=\frac{\mathrm{Br}(B\to D\tau {\nu }_{\tau })}{\mathrm{Br}(B\to D{\ell }^{\prime }{\nu }_{{\ell }^{\prime }})}$ $({\ell }^{\prime }=e,\mu )$ is also estimated and compared with the experimental data as well as other theoretical predictions.

    hep-phPRD(2021)·22 citations
13. 13*

    On the structure of the correlation coefficients S(E_e) and U(E_e) of the neutron beta decay

    A. N. Ivanov🇦🇹 · R. Höllwieser🇩🇪 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

    In the standard effective V - A theory of low-energy weak interactions (i.e. in the Standard Model (SM)) we analyze the structure of the correlation coefficients S(E_e) and U(E_e), where E_e is the electron energy. These correlation coefficients were introduced to the electron-energy and angular distribution of the neutron beta decay by Ebel and Feldman ( Nucl. Phys. 4, 213 (1957)) in addition to the set of correlation coefficients proposed by Jackson et al. (Phys. Rev. 106, 517 (1957)). The correlation coefficients $S(E_e)$ and $U(E_e)$ are induced by simultaneous correlations of the neutron and electron spins and electron and antineutrino 3-momenta. These correlation structures do no violate discrete P, C and T symmetries. We analyze the contributions of the radiative corrections of order O(alpha/pi), taken to leading order in the large nucleon mass m_N expansion, and corrections of order O(E_e/m_N), caused by weak magnetism and proton recoil. In addition to the obtained SM corrections we calculate the contributions of interactions beyond the SM (BSM contributions) in terms of the phenomenological coupling constants of BSM interactions by Jackson et al. (Phys. Rev. 106, 517 (1957)) and the second class currents by Weinberg (Phys. Rev. 112, 1375 (1958)).

    hep-phhep-exnucl-exnucl-thPRC(2021)·3 citations
14. 14*

    $\rho$ exchange contribution to neutrinoless double beta decay

    Namit Mahajan🇮🇳

    We consider $\rho$ meson contributions to neutrinoless double beta decay amplitude stemming from the hadronization of the short distance quark-electron currents. These contributions are evaluated within vacuum dominance approximation. The one and two $\rho$ exchange contributions affect the Fermi transition nuclear matrix element in a way that lead to near cancellations in the same chirality, left-left and right-right, short range amplitudes when these new contributions are combined with the conventional short range amplitudes, while the left-right amplitude almost triples. This then necessitates the inclusion of $\rho$ exchange amplitudes in any phenomenological study, like in left-right theories.

    hep-phEPJC(2023)·0 citations
15. 15*

    Contributions to $ZZ{V}^{\ast }$ ($V=\gamma ,Z,Z^{\prime }$) couplings from $CP$ violating flavor changing couplings

    A. I. Hernández-Juárez🇲🇽 · A. Moyotl🇲🇽 · G. Tavares-Velasco🇲🇽

    The one-loop contributions to the trilinear neutral gauge boson couplings $ZZ{V}^{\ast }$ ($V=\gamma ,Z,Z^{\prime }$), parametrized in terms of one $CP$-conserving $f_5^V$ and one $CP$-violating $f_4^V$ form factors, are calculated in models with $CP$-violating flavor changing neutral current couplings mediated by the $Z$ gauge boson and an extra neutral gauge boson $Z^{\prime }$. Analytical results are presented in terms of both Passarino-Veltman scalar functions and closed form functions. Constraints on the vector and axial couplings of the $Z$ gauge boson $\left|g_{VZ}^{tu}\right|<0.0096$ and $\left|g_{VZ}^{tc}\right|<0.011$ are obtained from the current experimental data on the $t\to Zq$ decays. It is found that in the case of the $ZZ{\gamma }^{\ast }$ vertex the only non-vanishing form factor is $f_5^{\gamma }$, which can be of the order of $10^{-3}$, whereas for the $ZZ{Z}^{\ast }$ vertex both form factors $f_5^Z$ and $f_4^Z$ are non-vanishing and can be of the order of $10^{-6}$ and $10^{-5}$, respectively. Our estimates for $f_5^{\gamma }$ and $f_5^Z$ are smaller than those predicted by the standard model, where $f_4^Z$ is absent up to the one loop level. We also estimate the $ZZ{Z^{\prime }}^{\ast }$ form factors arising from both diagonal and non-diagonal $Z^{\prime }$ couplings within a few extension models. It is found that in the diagonal case $f_5^{Z^{\prime }}$ is the only non-vanishing form factor and its real and imaginary parts can be of the order of $10^{-1}-10^{-2}$ and $10^{-2}-10^{-3}$, respectively, with the dominant contributions arising from the light quarks and leptons. In the non-diagonal case $f_5^{Z^{\prime }}$ can be of the order of $10^{-4}$, whereas $f_4^{Z^{\prime }}$ can reach values as large as $10^{-7}-10^{-8}$, with the largest contributions arising from the $Z^{\prime }tq$ couplings.

    hep-phEPJC(2021)·21 citations
16. 16*

    Lifshitz scaling, ringing black holes, and superradiance

    Naritaka Oshita🇨🇦 · Niayesh Afshordi🇨🇦 · Shinji Mukohyama🇯🇵

    We investigate the ringdown waveform and reflectivity of a Lifshitz scalar field around a fixed Schwarzschild black hole. The radial wave equation is modified due to the Lorentz breaking terms, which leads to a diversity of ringdown waveforms. Also, it turns out that Lifshitz waves scattered by the Schwarzschild black hole exhibits superradiance. The Lorentz breaking terms lead to superluminal propagation and high-frequency modes can enter and leave the interior of the Killing horizon where negativity of energy is not prohibited. This allows the Lifshitz waves to carry out additional positive energy to infinity while leaving negative energy inside the Killing horizon, similar to the Penrose process in the ergosphere of a Kerr spacetime. Another interesting phenomenon is emergence of long-lived quasinormal modes, associated with roton-type dispersion relations. These effects drastically modify the greybody factor of a microscopic black hole, whose Hawking temperature is comparable with or higher than the Lifshitz energy scale.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2021)·9 citations
17. 17*

    Parton collisional effect on the conversion of geometry eccentricities into momentum anisotropies in relativistic heavy-ion collisions

    Long Ma🇨🇳 · Guo-Liang Ma🇨🇳 · Yu-Gang Ma🇨🇳

    We explore parton collisional effects on the conversion of geometry eccentricities into azimuthal anisotropies in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV using a multi-phase transport model. The initial eccentricity ${\epsilon }_n$ (n = 2,3) and flow harmonics $v_n$ (n = 2,3) are investigated as a function of the number of parton collisions ($N_{coll}$) during the source evolution of partonic phase. It is found that partonic collisions leads to generate elliptic flow $v_2$ and triangular flow $v_3$ in Pb+Pb collisions. On the other hand, partonic collisions also result in an evolution of the eccentricity of geometry. The collisional effect on the flow conversion efficiency is therefore studied. We find that the partons with larger $N_{coll}$ show a lower flow conversion efficiency, which reflect differential behaviors with respect to $N_{coll}$. It provides an additional insight into the dynamics of the space-momentum transformation during the QGP evolution from a transport model point of view.

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

    Constraints on New Physics in the Electron g-2 from a Search for Invisible Decays of a Scalar, Pseudoscalar, Vector, and Axial Vector

    Yu.M. Andreev🇷🇺 · D. Banerjee🇨🇭 · J. Bernhard🇨🇭 · V.E. Burtsev🇷🇺 · A.G. Chumakov🇷🇺 · D. Cooke🇬🇧 · P. Crivelli🇨🇭 · E. Depero🇨🇭 · A.V. Dermenev🇷🇺 · S.V. Donskov🇷🇺 · R.R. Dusaev🇷🇺 · T. Enik🇷🇺 and 40 other authors

    We performed a search for a new generic $X$ boson, which could be a scalar ($S$), pseudoscalar ($P$), vector ($V$) or an axial vector ($A$) particle produced in the 100 GeV electron scattering off nuclei, $e^{-}Z\to e^{-}ZX$, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such process was found in the full NA64 data set of $2.84\times 10^{11}$ electrons on target. We place new bounds on the $S,P,V,A$ coupling strengths to electrons, and set constraints on their contributions to the electron anomalous magnetic moment $a_e$, $|\Delta a_X|\lesssim 10^{-15}-10^{-13}$ for the $X$ mass region $m_X\lesssim 1$ GeV. These results are an order of magnitude more sensitive compared to the current accuracy on $a_e$ from the electron $g-2$ experiments and recent high-precision determination of the fine structure constant.

    ↳ hep-exhep-phPRL(2021)·73 citations
19. 19*

    Conceptual Design Report for the LUXE Experiment

    Halina Abramowicz🇮🇱 · Uwe Hernandez Acosta🇩🇪 · Massimo Altarelli🇩🇪 · Ralph Assmann🇩🇪 · Zhaoyu Bai🇮🇱 · Ties Behnke🇩🇪 · Yan Benhammou🇮🇱 · Thomas Blackburn🇸🇪 · Stewart Boogert🇬🇧 · Oleksandr Borysov🇩🇪 · Maryna Borysova🇩🇪 · Reinhard Brinkmann🇩🇪 and 79 other authors

    This Conceptual Design Report describes LUXE (Laser Und XFEL Experiment), an experimental campaign that aims to combine the high-quality and high-energy electron beam of the European XFEL with a powerful laser to explore the uncharted terrain of quantum electrodynamics characterised by both high energy and high intensity. We will reach this hitherto inaccessible regime of quantum physics by analysing high-energy electron-photon and photon-photon interactions in the extreme environment provided by an intense laser focus. The physics background and its relevance are presented in the science case which in turn leads to, and justifies, the ensuing plan for all aspects of the experiment: Our choice of experimental parameters allows (i) effective field strengths to be probed at and beyond the Schwinger limit and (ii) a precision to be achieved that permits a detailed comparison of the measured data with calculations. In addition, the high photon flux predicted will enable a sensitive search for new physics beyond the Standard Model. The initial phase of the experiment will employ an existing 40 TW laser, whereas the second phase will utilise an upgraded laser power of 350 TW. All expectations regarding the performance of the experimental set-up as well as the expected physics results are based on detailed numerical simulations throughout.

    ↳ hep-exhep-phquant-phEur.Phys.J.ST(2021)·231 citations
20. 20*

    Large-$N_c$ analysis of two-nucleon neutrinoless double beta decay and charge-independence-breaking contact terms

    Thomas R. Richardson🇺🇸 · Matthias R. Schindler🇺🇸 · Saori Pastore🇺🇸 · Roxanne P. Springer🇺🇸

    The interpretation of experiments that search for neutrinoless double beta decay relies on input from nuclear theory. Cirigliano et al. recently showed that, for the light Majorana exchange formalism, effective field theory calculations require a $nn\to pp{e}^{-}{e}^{-}$ contact term at leading order. They estimated the size of this contribution by relating it to measured charge-independence-breaking (CIB) nucleon-nucleon interactions and making an assumption about the relative sizes of CIB operators. We show that the assumptions underlying this approximation are justified in the limit of the number of colors $N_c$ being large. We also obtain a large-$N_c$ hierarchy among CIB nucleon-nucleon interactions that is in agreement with phenomenological results.

    ↳ nucl-thhep-phPRC(2021)·36 citations
21. 21*

    A deep search for decaying dark matter with XMM-Newton blank-sky observations

    Joshua W. Foster🇺🇸 · Marius Kongsore🇺🇸 · Christopher Dessert🇺🇸 · Yujin Park🇺🇸 · Nicholas L. Rodd🇺🇸 · Kyle Cranmer🇺🇸 · Benjamin R. Safdi🇺🇸

    Sterile neutrinos with masses in the keV range are well-motivated extensions to the Standard Model that could explain the observed neutrino masses while also making up the dark matter (DM) of the Universe. If sterile neutrinos are DM then they may slowly decay into active neutrinos and photons, giving rise to the possibility of their detection through narrow spectral features in astrophysical X-ray data sets. In this work, we perform the most sensitive search to date for this and other decaying DM scenarios across the mass range from 5 to 16 keV using archival XMM-Newton data. We reduce 547 Ms of data from both the MOS and PN instruments using observations taken across the full sky and then use this data to search for evidence of DM decay in the ambient halo of the Milky Way. We determine the instrumental and astrophysical baselines with data taken far away from the Galactic Center, and use Gaussian Process modeling to capture additional continuum background contributions. No evidence is found for unassociated X-ray lines, leading us to produce the strongest constraints to date on decaying DM in this mass range.

    ↳ astro-ph.COastro-ph.HEhep-phPRL(2021)·185 citations
22. 22*

    Substructure at High Speed II: The Local Escape Velocity and Milky Way Mass with Gaia DR2

    Lina Necib🇺🇸 · Tongyan Lin🇺🇸

    Measuring the escape velocity of the Milky Way is critical in obtaining the mass of the Milky Way, understanding the dark matter velocity distribution, and building the dark matter density profile. In Necib $\&$ Lin (2021), we introduced a strategy to robustly measure the escape velocity. Our approach takes into account the presence of kinematic substructures by modeling the tail of the stellar distribution with multiple components, including the stellar halo and the debris flow called the Gaia Sausage (Enceladus). In doing so, we can test the robustness of the escape velocity measurement for different definitions of the "tail" of the velocity distribution, and the consistency of the data with different underlying models. In this paper, we apply this method to the second data release of Gaia and find that a model with at least two components is preferred. Based on a fit with three bound components to account for the disk, relaxed halo, and the Gaia Sausage, we find the escape velocity of the Milky Way at the solar position to be $v_{\mathrm{esc}}=484.6_{-7.4}^{+17.8}$ km/s. Assuming a Navarro-Frenck-White dark matter profile, and taken in conjunction with a recent measurement of the circular velocity at the solar position of $v_c=230\pm 10$ km/s, we find a Milky Way concentration of $c_{200}=13.8_{-4.3}^{+6.0}$ and a mass of $M_{200}=7.0_{-1.2}^{+1.9}\times 10^{11}{M}_{\odot }$, which is considerably lighter than previous measurements.

    ↳ astro-ph.GAhep-phApJ(2022)·27 citations
23. 23*

    Reconstructing the graviton

    Alfio Bonanno🇮🇹 · Tobias Denz🇩🇪 · Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧

    We reconstruct the Lorentzian graviton propagator in asymptotically safe quantum gravity from Euclidean data. The reconstruction is applied to both the dynamical fluctuation graviton and the background graviton propagator. We prove that the spectral function of the latter necessarily has negative parts similar to, and for the same reasons, as the gluon spectral function. In turn, the spectral function of the dynamical graviton is positive. We argue that the latter enters cross sections and other observables in asymptotically safe quantum gravity. Hence, its positivity may hint at the unitarity of asymptotically safe quantum gravity.

    ↳ hep-thgr-qchep-phSciPost Phys.(2022)·127 citations
24. 24*

    Neutrino signal dependence on gamma-ray burst emission mechanism

    Tetyana Pitik🇩🇰 · Irene Tamborra (Niels Bohr Institute)🇩🇰 · Maria Petropoulou (University of Athens)🇬🇷

    Long duration gamma-ray bursts (GRBs) are among the least understood astrophysical transients powering the high-energy universe. To date, various mechanisms have been proposed to explain the observed electromagnetic GRB emission. In this work, we show that, although different jet models may be equally successful in fitting the observed electromagnetic spectral energy distributions, the neutrino production strongly depends on the adopted emission and dissipation model. To this purpose, we compute the neutrino production for a benchmark high-luminosity GRB in the internal shock model, including a dissipative photosphere as well as three emission components, in the jet model invoking internal-collision-induced magnetic reconnection and turbulence (ICMART), in the case of a magnetic jet with gradual dissipation, and in a jet with dominant proton synchrotron radiation. We find that the expected neutrino fluence can vary up to three orders of magnitude in amplitude and peak at energies ranging from $10^4$ to $10^8$ GeV. For our benchmark input parameters, none of the explored GRB models is excluded by the targeted searches carried out by the IceCube and ANTARES Collaborations. However, our work highlights the potential of high-energy neutrinos of pinpointing the underlying GRB emission mechanism and the importance of relying on different jet models for unbiased stacking searches.

    ↳ astro-ph.HEhep-phJCAP(2021)·34 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.