Fri·May 13, 2022Friday·May 13, 2022

1. 01*

   Search for baryon junctions in photonuclear processes and isobar collisions at RHIC

   Nicole Lewis🇺🇸 · Wendi Lv🇨🇳 · Mason Alexander Ross🇺🇸 · Chun Yuen Tsang🇺🇸 · James Daniel Brandenburg🇺🇸 · Zi-Wei Lin🇺🇸 · Rongrong Ma🇺🇸 · Zebo Tang🇨🇳 · Prithwish Tribedy🇺🇸 · Zhangbu Xu🇺🇸

   During the early development of Quantum Chromodynamics, it was proposed that baryon number could be carried by a non-perturbative Y-shaped topology of gluon fields, called the gluon junction, rather than by the valence quarks as in the QCD standard model. A puzzling feature of ultra-relativistic nucleus-nucleus collisions is the apparent substantial baryon excess in the midrapidity region that could not be adequately accounted for in most conventional models of quark and diquark transport. The transport of baryonic gluon junctions is predicted to lead to a characteristic exponential distribution of net-baryon density with rapidity and could resolve the puzzle. In this context we point out that the rapidity density of net-baryons near midrapidity indeed follows an exponential distribution with a slope of $-0.61\pm 0.03$ as a function of beam rapidity in the existing global data from A+A collisions at AGS, SPS and RHIC energies. To further test if quarks or gluon junctions carry the baryon quantum number, we propose to study the absolute magnitude of the baryon vs. charge stopping in isobar collisions at RHIC. We also argue that semi-inclusive photon-induced processes ($\gamma +p$/A) at RHIC kinematics provide an opportunity to search for the signatures of the baryon junction and to shed light onto the mechanisms of observed baryon excess in the mid-rapidity region in ultra-relativistic nucleus-nucleus collisions. Such measurements can be further validated in A+A collisions at the LHC and $e+p$/A collisions at the EIC.

   hep-phnucl-exnucl-thEPJC(2024)·37 citations
2. 02*

   Towards a full description of MeV dark matter decoupling: a self-consistent determination of relic abundance and $N_{\mathrm{eff}}$

   Xiaoyong Chu🇦🇹 · Jui-Lin Kuo🇺🇸 · Josef Pradler🇦🇹

   Thermal dark matter at the MeV mass-scale has its abundance set during the highly non-trivial epochs of neutrino decoupling and electron annihilation. The technical obstacles attached to solving Boltzmann equations of multiple interacting sectors being both relativistic and non-relativistic have to-date prevented the full treatment of this problem. Here, for the first time, we calculate the freeze-out of light dark matter, taking into account the energy transfer between the dark sector, neutrinos, and the electromagnetically interacting plasma from annihilation and elastic scattering processes alike. We develop a numerically feasible treatment that allows to track photon and neutrino temperatures across freeze-out and to arrive at a precision prediction of $N_{\mathrm{eff}}$ for arbitrary branching ratios of the dark matter annihilation channels. In addition, our treatment resolves for the first time the dark matter temperature evolution across freeze-out involving three sectors. It enters in the efficiency of velocity-dependent annihilation channels and for a flavor-blind $p$-wave annihilation into electron- and neutrino-pairs of all generations, we find the present Planck data excludes a complex scalar dark matter particle of mass of $m_{\varphi }\le 7$ MeV.

   hep-phastro-ph.HEPRD(2022)·31 citations
3. 03*

   Gravitational waves from neutrino mass genesis

   Pasquale Di Bari🇬🇧

   The discovery of gravitational waves opens new opportunities to test BSM physics. In particular, the production of a stochastic background of primordial gravitational waves could provide a signature of the generation of the right-right Majorana neutrino mass term necessary, within type-I seesaw mechanism, to explain lightness of neutrinos and their mixing parameters. I will discuss the possibility that such a generation occurs during a strong first order phase transition within Majoron models [1]. As well known, this can indeed produce a stochastic background of gravitational waves. The scale of the phase transition can or cannot coincide with the seesaw scale. In the latter case a low scale phase transition, occurring in the pre-recombination era, might be tested at very low frequencies ($10^{-9}$--$10^{-6}\mathrm{Hz}$). Even though the signal can hardly reproduce the NANOGrac putative signal such new physics at low scale might help ameliorating the tensions in the $\Lambda$CDM cosmological model (e.g., the Hubble tension). I will also discuss how a phase transition might be responsible for the generation of dark matter in the form of dark neutrinos coupling to the seesaw neutrinos via Higgs induced right handed-right handed neutrino mixing [2].

   hep-phPoS(2022)·0 citations
4. 04*

   Combining nonperturbative transverse momentum dependence with TMD evolution

   J. O. Gonzalez-Hernandez🇮🇹 · T. C. Rogers🇺🇸 · N. Sato🇺🇸

   Central to understanding the nonpertubative, intrinsic partonic nature of hadron structure are the concepts of transverse momentum dependent (TMD) parton distribution and fragmentation functions. A TMD factorization approach to the phenomenology of semi-inclusive processes that includes evolution, higher orders, and matching to larger transverse momentum, is ultimately necessary for reliably connecting with phenomenologically extracted nonperturbative structures, especially when widely different scales are involved. In this paper, we will address some of the difficulties that arise when phenomenological techniques that were originally designed for very high energy applications are extended to studies of hadron structures, and we will solidify the connection between standard high energy TMD implementations and the more intuitive, parton model based approaches to phenomenology that emphasize nonperturbative hadron structure. In the process, we will elaborate on differences between forward and backward TMD evolution, which in the context of this paper we call "bottom-up" and "top-down" approaches, and we will explain the advantages of a bottom-up strategy. We will also emphasize and clarify the role of the integral relations that connect TMD and collinear correlation functions. We will show explicitly how they constrain the nonperturbative "$g$-functions" of standard Collins-Soper-Sterman (CSS) implementations of TMD factorization. This paper is especially targeted toward phenomenologists and model builders who are interested in merging specific nonperturbative models and calculations (including lattice QCD) with TMD factorization at large $Q$. Our main result is a recipe for incorporating nonperturbative models into TMD factorization, and for constraining their parameters in a way that matches to perturbative QCD and evolution.

   hep-phhep-exnucl-exnucl-thPRD(2022)·23 citations
5. 05*

   Dirac dark matter, neutrino masses, and dark baryogenesis

   Diego Restrepo🇨🇴 · Andrés Rivera🇨🇴 · Walter Tangarife🇺🇸

   We present a gauged baryon number model as an example of models where all new fermions required to cancel out the anomalies help to solve phenomenological problems of the standard model (SM). Dark fermion doublets, along with the iso-singlet charged fermions, in conjunction with a set of SM-singlet fermions, participate in the generation of small neutrino masses through the Dirac-dark Zee mechanism. The other SM-singlets explain the dark matter in the Universe, while their coupling to an inert singlet scalar is the source of the $CP$ violation. In the presence of a strong first-order electroweak phase transition, this "dark" $CP$ violation allows for a successful electroweak baryogenesis mechanism.

   hep-phPRD(2022)·6 citations
6. 06*

   Fermion Mass Hierarchy and Mixing in simplified Grand Gauge-Higgs Unification

   Nobuhito Maru🇯🇵 · Haruki Takahashi🇯🇵 · Yoshiki Yatagai🇯🇵

   Grand gauge-Higgs unification of five dimensional SU(6) gauge theory on an orbifold $S^1/Z_2$ with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on the boundaries and some massive bulk fermions coupling to the SM fermions are introduced. The number of the bulk fermions is reduced compared to the previous model, which reproduces the generation mixing of the SM fermions in addition to the SM fermion mass hierarchy by mild tuning the bulk masses and parameters of the localized gauge kinetic terms.

   hep-phhep-thJ.Phys.G(2023)·4 citations
7. 07*

   Towards the discovery of novel $B_c$ states: radiative and hadronic transitions

   B. Martín-González🇪🇸 · P. G. Ortega🇪🇸 · D. R. Entem🇪🇸 · F. Fernández🇪🇸 · J. Segovia🇪🇸

   The properties of the $B_c$-meson family ($c\bar{b}$) are still not well determined experimentally because the specific mechanisms of formation and decay remain poorly understood. Unlike heavy quarkonia, i.e. the hidden heavy quark-antiquark sectors of charmonium ($c\bar{c}$) and bottomonium ($b\bar{b}$), the $B_c$-mesons cannot annihilate into gluons and they are, consequently, more stable. The excited $B_c$ states, lying below the lowest strong-decay $BD$-threshold, can only undergo through radiative decays and hadronic transitions to the $B_c$ ground state, which then decays weakly. As a result of this, a rich spectrum of narrow excited states below the $BD$-threshold appear, whose total widths are two orders of magnitude smaller than those of the excited levels of charmonium and bottomonium. In a different article, we determined bottom-charmed meson masses using a non-relativistic constituent quark model which has been applied to a wide range of hadron physical observables, and thus the model parameters are completely constrained. Herein, continuing to our study of the $B_c$ sector, we calculate the relevant radiative decay widths and hadronic transition rates between $c\bar{b}$ states which are below $BD$-threshold. This shall provide the most promising signals for discovering excited $B_c$ states that are below the lowest strong-decay $BD$-threshold. Finally, our results are compared with other models to measure the reliability of the predictions and point out differences.

   hep-phhep-exhep-latnucl-ex+1PRD(2022)·27 citations
8. 08*

   A method for approximating optimal statistical significances with machine-learned likelihoods

   Ernesto Arganda🇪🇸 · Xabier Marcano🇪🇸 · Víctor Martín Lozano🇩🇪 · Anibal D. Medina🇦🇷 · Andres D. Perez🇦🇷 · Manuel Szewc🇦🇷 · Alejandro Szynkman🇦🇷

   Machine-learning techniques have become fundamental in high-energy physics and, for new physics searches, it is crucial to know their performance in terms of experimental sensitivity, understood as the statistical significance of the signal-plus-background hypothesis over the background-only one. We present here a simple method that combines the power of current machine-learning techniques to face high-dimensional data with the likelihood-based inference tests used in traditional analyses, which allows us to estimate the sensitivity for both discovery and exclusion limits through a single parameter of interest, the signal strength. Based on supervised learning techniques, it can perform well also with high-dimensional data, when traditional techniques cannot. We apply the method to a toy model first, so we can explore its potential, and then to a LHC study of new physics particles in dijet final states. Considering as the optimal statistical significance the one we would obtain if the true generative functions were known, we show that our method provides a better approximation than the usual naive counting experimental results.

   hep-phastro-ph.IMhep-exphysics.data-anEPJC(2022)·17 citations
9. 09*

   Partial wave analysis for the in-hadron condensate

   Pianpian Qin🇨🇳 · Zhan Bai🇨🇳 · Muyang Chen🇨🇳 · Si-xue Qin🇨🇳

   In-hadron condensates, defined as the scalar form factors at zero-momentum transfer, are investigated for flavor-symmetric mesons in pseudoscalar and vector channels under the rainbow-ladder truncation within the Dyson-Schwinger equations framework. We confirm the efficiency of the in-hadron condensates in describing the effects of dynamical chiral symmetry breaking from both global and structural perspectives by comparing the meson masses, the dimensionless in-hadron condensates, and the partial wave decompositions of in-hadron condensates as functions of current-quark mass. From partial wave analysis, we infer $\pi (1300)$ is a radial excitation dominated by $s$ waves and $\rho (1450)$ is not a $p$ wave-dominated excitation. This work provides a new insight into the studies of hadron properties with partial wave analysis for the in-hadron condensates.

   hep-phPRD(2022)·4 citations
10. 10*

    The vector boson transverse momentum distributions

    Ignazio Scimemi🇪🇸

    The transverse momentum dependent distributions (TMD) are an essential part of the factorization theorems in vector boson production. They are non-perturbative, double scale dependent functions that asymptotically match onto collinear parton distributions functions (PDF). Once TMD are expressed using PDF, one observes that they are sensitive to the choice and quality of PDF sets (PDF bias). A solution to this problem is found and discussed. Nevertheless the main source of error on vector boson spectra still comes from PDF uncertainty propagation.

    hep-phhep-exnucl-exnucl-th1 citation
11. 11*

    A new viable mass region of Dark matter and Dirac neutrino mass generation in a scotogenic extension of SM

    Nilavjyoti Hazarika🇮🇳 · Kalpana Bora🇮🇳

    We propose a scotogenic extension of the Standard Model which can provide a scalar Dark Matter candidate in the new, theoretically previously unaddressed, intermediate region ($200\le M_{DM}\le 550$ GeV) and also generate light Dirac neutrino masses. In this framework, the standard model is extended by three gauge singlet fermions, two singlet scalar fields, and one additional scalar doublet, all of which are odd under $Z_2\times Z_4$ discrete symmetry. These additional symmetries prevent the singlet fermions from obtaining Majorana mass terms along with providing the stability to the dark matter candidate. It is known that in the case of the scalar singlet DM model, the only region which is not yet excluded is a narrow region close to the Higgs resonance $m_S\simeq \frac{m_h}{2}$ - others ruled out from different experimental and theoretical bounds. In the case of the Inert doublet model, the mass region ($\sim 60$-$80$ GeV) and the high mass region (heavier than $550$ GeV) are allowed. This motivates us to explore a parameter range in the intermediate-mass region $M_W\le M_{DM}\le 550$ GeV, which we do in a scotogenic extension of SM with a scalar doublet and scalar singlets. The dark matter in our model is a mixture of singlet and doublet scalars. We constrain the allowed parameter space of the model using Planck bound on present dark matter relic abundance, neutrino mass, and the latest bound on spin-independent DM-nucleon scattering cross-section from XENON1T experiment. Our model may provide a viable DM candidate in the new, previously unexplored mass range ($200\le M_{DM}\le 550$ GeV), if this new window for the DM candidate mass is detected in future experiments, along with explanation of Dirac mass of neutrinos, since so far there is no strong evidence in support of Majorana nature of neutrino mass.

    hep-phInt.J.Mod.Phys.A(2023)·9 citations
12. 12*

    Muon-electron backward scattering: a prime example for endpoint singularities in SCET

    Guido Bell🇩🇪 · Philipp Böer🇩🇪 · Thorsten Feldmann🇩🇪

    We argue that energetic muon-electron scattering in the backward direction can be viewed as a template case to study the resummation of large logarithms related to endpoint divergences appearing in the effective-theory formulation of hard-exclusive processes. While it is known since the mid sixties that the leading double logarithms from QED corrections resum to a modified Bessel function on the amplitude level, the modern formulation in Soft-Collinear Effective Theory (SCET) shows a surprisingly complicated and iterative pattern of endpoint-divergent convolution integrals. In contrast to the bottom-quark induced $h\to \gamma \gamma$ decay, for which a renormalized factorization theorem has been proposed recently, we find that rapidity logarithms generate an infinite tower of collinear-anomaly exponents. This can be understood as a generic consequence of the underlying $2\to 2$ kinematics. Using endpoint refactorization conditions for the collinear matrix elements, we show how the Bessel function is reproduced in the effective theory from consistency relations between quantities in a "bare" factorization theorem.

    hep-phJHEP(2022)·48 citations
13. 13*

    Dispersive bounds for local form factors in ${\Lambda }_b\to \Lambda$ transitions

    Thomas Blake🇬🇧 · Stefan Meinel🇺🇸 · Muslem Rahimi🇩🇪 · Danny van Dyk🇩🇪

    We investigate the ten independent local form-factors relevant to the $b$-baryon decay ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$, combining information of lattice QCD and dispersive bounds. We propose a novel parametrization of the form factors in terms of orthonormal polynomials that diagonalizes the form factor contributions to the dispersive bounds. This is a generalization of the unitarity bounds developed for meson-to-meson form-factors. In contrast to ad-hoc parametrizations of these form factors, our parametrization provides a degree of control of the form-factor uncertainties at large hadronic recoil. This is of phenomenological interest for theoretical predictions of, e.g., ${\Lambda }_b\to \Lambda \gamma$ and ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ decay processes.

    hep-phhep-latPRD(2023)·39 citations
14. 14*

    Decay properties of $N(1535)$ in the holographic QCD

    Akihiro Iwanaka🇯🇵 · Daisuke Fujii🇯🇵 · Atsushi Hosaka🇯🇵

    We study one pion emission decay of the first excited state of the nucleon with negative parity $N(1535)\equiv N^{\ast }$ in the holographic model of QCD. The excited state is described as a vibrational mode along the extra $z$ direction in the five-dimensional space-time of the model. We have obtained an analytic formula for the axial coupling of $g_A^{N{N}^{\ast }}$. The off-diagonal axial coupling is obtained at the decaying pion momentum $|\mathbf{k}|=448$ MeV as $g_A^{N{N}^{\ast }}\sim 0.32$, and hence a partial decay width ${\Gamma }_{N^{\ast }\to \pi N}\sim 30$ MeV, which is smaller than but reasonably compared to the experimental data.

    hep-phPRD(2022)·9 citations
15. 15*

    Renormalization-group improved Higgs to two gluons decay rate

    Gauhar Abbas🇮🇳 · Astha Jain🇮🇳 · Vartika Singh🇮🇳 · Neelam Singh🇮🇳

    We investigate the renormalization-group scale and scheme dependence of the $H\to gg$ decay rate at the order N${}^4$LO in the renormalization-group summed perturbative theory, which employs the summation of all renormalization-group accessible logarithms including the leading and subsequent four sub-leading logarithmic contributions to the full perturbative series expansion. Moreover, we study the higher-order behaviour of the $H\to gg$ decay width using the asymptotic Padé approximant method in four different renormalization schemes. Furthermore, the higher-order behaviour is independently investigated in the framework of the asymptotic Padé-Borel approximant method where generalized Borel-transform is used as an analytic continuation of the original perturbative expansion. The predictions of the asymptotic Padé-Borel approximant method are found to be in agreement with that of the asymptotic Padé approximant method. Finally, we provide the $H\to gg$ decay rate at the order N${}^5$LO in the fixed-order ${\Gamma }_{{\mathrm{N}}^5\mathrm{LO}}={\Gamma }_0(1.8375\pm 0.047_{{\alpha }_s(M_Z),1\%}\pm 0.0004_{M_t}\pm 0.0066_{M_H}\pm 0.0036_{\mathrm{P}}\pm 0.007_{\text{s}}\pm 0.0005_{sc}),$ and ${\Gamma }_{\mathrm{RGS}{\mathrm{N}}^5\mathrm{LO}}={\Gamma }_0(1.841\pm 0.047_{{\alpha }_s(M_Z),1\%}\pm 0.0005_{M_t}\pm 0.0066_{M_H}\pm 0.0002_{\mu }\pm 0.0027_{\mathrm{P}}\pm 0.001_{sc})$ in the renormalization-group summed perturbative theories.

    hep-phhep-exEur.Phys.J.Plus(2024)·9 citations
16. 16*

    ${\Lambda }_b\to p,N^{\ast }(1535)$ Form Factors from QCD Light-Cone Sum Rules

    Ke-Sheng Huang🇨🇳 · Wei Liu🇨🇳 · Yue-Long Shen🇨🇳 · Fu-Sheng Yu🇨🇳

    In this work we calculate the transition form factors of ${\Lambda }_b$ decaying into proton and $N^{\ast }(1535)$ ($J^P={1/2}^{+}$ and ${1/2}^{-}$ respectively), within the framework of light-cone sum rules with the distribution amplitudes (DAs) of ${\Lambda }_b$-baryon. In the hadronic representation of the correlation function, we have isolated both the proton and the $N^{\ast }(1535)$ states so that the ${\Lambda }_b\to p,N^{\ast }(1535)$ form factors can be evaluated simultaneously. Due to the less known properties of baryons, we investigate three interpolating currents of the light baryons and five parametrization models for DAs of ${\Lambda }_b$. Numerically, our predictions on the ${\Lambda }_b\to p$ form factors and the branching fractions of ${\Lambda }_b\to p\ell \nu$ from the Ioffe or the tensor currents are consistent with the Lattice simulation and the results from the light-baryon sum rules, as well as the experimental data of $Br({\Lambda }_b^0\to p{\mu }^{-}\bar{\nu })$. The predictions on the form factors of ${\Lambda }_b\to N^{\ast }(1535)$ are very sensitive to the choice of the interpolating currents so that the relevant measurement could be helpful to clarify the properties of baryons.

    hep-phhep-exEPJC(2023)·18 citations
17. 17*

    Higher-order QCD corrections to ${\rm Y}$ decay into double charmonia

    Yu-Dong Zhang🇨🇳 · Wen-Long Sang🇨🇳 · Hong-Fei Zhang🇨🇳

    In this work, we study the exclusive decay of ${\rm Y}$ into $J/\psi$ in association with ${\eta }_c$ (${\chi }_{c0,1,2}$). The decay widths for different helicity configurations are evaluated up to QCD next-to-leading order within the nonrelativistic QCD framework. We find that the QCD corrections notably mitigate the renormalization scale dependence of the decay widths for all the processes. The branching fraction of ${\rm Y}\to J/\psi +{\chi }_{c1}$ is obtained as $3.73_{-2.06-1.19}^{+5.10+0.10}\times 10^{-6}$, which agrees well with the Belle measurement, i.e., $\mathrm{Br}({\rm Y}\to J/\psi +{\chi }_{c1})=(3.90\pm 1.21\pm 0.23)\times 10^{-6}$. For the other processes, our results of the branching fractions are compatible with the upper limits given by the Belle experiments, except for ${\rm Y}(2S)\to J/\psi +{\chi }_{c1}$, where some tension exists between theory and experiment. Having the polarized decay widths, we study the $J/\psi$ polarization, which turn out to be independent of any nonperturbative parameters. Further, according to our calculation, it is promising to measure all the processes at Super B factory thanks to the high luminosity.

    hep-phhep-exPRL(2022)·5 citations
18. 18*

    Notes on QED Corrections in Weak Decays

    Roman Zwicky🇬🇧

    In these lecture notes the basics of QED corrections to hadronic decays are reviewed with special emphasis on conceptual (e.g. counting and tracking of infrared sensitive logs) rather than numerical aspects. General matters are illustrated for the cases of increased complexity and decreased inclusiveness: $e^{+}{e}^{-}\to hadrons$, the leptonic decay ${\pi }^{+}\to {\ell }^{+}\bar{\nu }$ and the semileptonic decay $B\to \pi {\ell }^{+}\bar{\nu }$. The non-trivial and ongoing efforts of including structure dependence are very briefly outlined.

    hep-phhep-latSymmetry(2021)·9 citations
19. 19*

    Supernova fast flavor conversions in 1+1D : Influence of mu-tau neutrinos

    Francesco Capozzi🇪🇸 · Madhurima Chakraborty🇮🇳 · Sovan Chakraborty🇮🇳 · Manibrata Sen🇩🇪

    In the dense supernova environment, neutrinos can undergo fast flavor conversions which depend on the large neutrino-neutrino interaction strength. It has been recently shown that both their presence and outcome can be affected when passing from the commonly used three neutrino species approach to the more general one with six species. Here, we build up on a previous work performed on this topic and perform a numerical simulation of flavor evolution in both space and time, assuming six neutrino species. We find that the results presented in our previous work remain qualitatively the same even for flavor evolution in space and time. This emphasizes the need for going beyond the simplistic approximation with three species when studying fast flavor conversions.

    hep-phPRD(2022)·25 citations
20. 20*

    Ultra-wide Bandwidth Observations of 19 pulsars with Parkes telescope

    Z. R. Zhou🇨🇳 · J. B. Wang🇨🇳 · N. Wang🇨🇳 · G. Hobbs🇦🇺 · S. Q. Wang🇨🇳

    Flux densities are basic observation parameters to describe pulsars. In the most updated pulsar catalog, 24% of the listed radio pulsars have no flux density measurement at any frequency. Here, we report the first flux density measurements, spectral indices, pulse profiles, and correlations of the spectral index with pulsar parameters for 19 pulsars employing the Ultra-Wideband Low (UWL) receiver system installed on the Parkes radio telescope. The results for spectral indices of 17 pulsars are in the range between -0.6 and -3.10. The polarization profiles of thirteen pulsars are shown. There is a moderate correlation between the spectral index and spin frequency. For most pulsars detected, the S/N ratio of pulse profile is not high, so DM, Faraday rotation measure (RM), and polarization can not be determined precisely. Twenty-nine pulsars were not detected in our observations. We discuss the possible explanations for why these pulsars were not detected.

    ↳ astro-ph.HEastro-ph.GAastro-ph.SRhep-phRes.Astron.Astrophys.(2022)·1 citation
21. 21*

    Consistency study of high- and low-accreting Mg ii quasars: No significant effect of the Fe ii to Mg ii flux ratio on the radius-luminosity relation dispersion

    Narayan Khadka🇺🇸 · Michal Zajaček🇨🇿 · Swayamtrupta Panda🇵🇱 · Mary Loli Martínez-Aldama🇨🇱 · Bharat Ratra🇺🇸

    We use observations of 66 reverberation-measured \Mgii\ quasars (QSOs) in the redshift range $0.36\le z\le 1.686$ -- a subset of the 78 QSOs we previously studied that also have \rfe\ (flux ratio parameter of UV \Feii\ to \Mgii\ that is used as an accretion-rate proxy) measurements -- to simultaneously constrain cosmological model parameters and QSO 2-parameter and 3-parameter radius-luminosity ($R-L$) relation parameters in six different cosmological models. We find that these QSO $R-L$ relation parameters are independent of the assumed cosmological model and so these QSOs are standardizable through the $R-L$ relations. Also: (1) With the 2-parameter $R-L$ relation, we find that the low-\rfe\ and high-\rfe\ data subsets obey the same $R-L$ relation within the error bars. (2) Extending the 2-parameter $R-L$ relation to a 3-parameter one does not result in the hoped-for reduction in the intrinsic dispersion of the $R-L$ relation. (3) Neither of the 3-parameter $R-L$ relations provide a significantly better fit to the measurements than does the 2-parameter $R-L$ relation. These are promising results for the on-going development of \Mgii\ cosmological probes. The first and third of these results differ significantly from those we found elsewhere from analyses of reverberation-measured \hb\ QSOs.

    ↳ astro-ph.COgr-qchep-phMNRAS(2022)·27 citations
22. 22*

    VLBI observations of VIK J2318-3113, a quasar at z = 6.44

    Y. Zhang🇨🇳 · T. An🇨🇳 · A. Wang🇺🇸 · S. Frey🇨🇳 · L. I. Gurvits🇳🇱 · K. E. Gabanyi🇭🇺 · K. Perger🇭🇺 · Z. Paragi🇳🇱

    The nature of jets in active galactic nuclei (AGN) in the early Universe and their feedback to the host galaxy remain a highly topical question. Observations of the radio structure of high-redshift AGNs enabled by very long baseline interferometry (VLBI) provide indispensable input into studies of their properties and role in the galaxies' evolution. Up to now, only five AGNs at redshift $z>6$ have been studied with the VLBI technique. VIKJ2318-3113 is a recently discovered quasar at z = 6.44 that has not been imaged with VLBI before the current work. Here we present the first VLBI imaging results of this high-redshift quasar, with the aim of corroborating its high-resolution appearance with the physical model of the object. We carried out VLBI phase-referencing observations of VIKJ2318-3113 using the Very Long Baseline Array at two frequencies, 1.6 and 4.7 GHz, and obtained the first view at the radio structure on the milliarcsecond scale. The source was clearly detected at 1.6 GHz. We found that almost all of its radio emission comes from the pc-scale core region. Our dual-frequency observations constrain the spectral index and brightness temperature of the radio core. Its properties are similar to those of other known high-redshift radio-loud AGNs.

    ↳ astro-ph.COastro-ph.HEhep-exhep-phAstron.Astrophys.(2022)·12 citations
23. 23*

    Emergent Early Universe Cosmology from BFSS Matrix Theory

    Suddhasattwa Brahma🇬🇧 · Robert Brandenberger🇨🇦 · Samuel Laliberte🇨🇦

    The BFSS matrix model is a suggested non-perturbative definition of string theory. Starting from a thermal state of this matrix model, we show how space and time can emerge dynamically. Results from the IKKT matrix model indicate that the $SO(9)$ symmetry of space is spontaneously broken to $SO(3)\times SO(6)$, with the three-dimensional subspace becoming large. Given this initial state for the universe, we show that cosmological perturbations and gravitational waves with scale-invariant spectra are generated, without the need of postulating an early phase of cosmological inflation. The Big Bang singularity is automatically resolved.

    ↳ hep-thastro-ph.COgr-qchep-phInt.J.Mod.Phys.D(2022)·11 citations
24. 24*

    Prospects for Higgs boson and new scalar resonant production searches in ttbb final state at the LHC

    Petr Mandrik🇷🇺

    In this article we probe resonant associated production of a Standard Model Higgs boson with new heavy scalar resonant in proton-proton collisions at a center-of-mass energy $\sqrt{s}=13$ TeV. The Higgs boson and new scalar resonant are required to decay into a pair of bottom quarks and a pair of top quarks, respectively. Semileptonic decay of top quarks is considered. The searches are projected into operation conditions of the Large Hadron Collider during Run II data taking period at a center-of-mass energy of 13 TeV using Monte Carlo generated events, realistic detector response simulation and available Open Data samples. Analysis strategies are summarized and machine learning approach using Deep Neural Network is proposed to resolve ambiguous in jets assignment and improve kinematic reconstruction of signal events. Sensitivity of the CMS detector is estimated as 95% expected upper limits on the product of the production cross section and the branching fractions of the searched process.

    ↳ hep-exhep-phNPB(2023)·0 citations
25. 25*

    Towards glueball masses of large-$N$ $\mathrm{SU}(N)$ pure-gauge theories without topological freezing

    Claudio Bonanno🇮🇹 · Massimo D'Elia🇮🇹 · Biagio Lucini🇬🇧 · Davide Vadacchino🇬🇧

    In commonly used Monte Carlo algorithms for lattice gauge theories the integrated autocorrelation time of the topological charge is known to be exponentially-growing as the continuum limit is approached. This $topological\text{freezing}$, whose severity increases with the size of the gauge group, can result in potentially large systematics. To provide a direct quantification of the latter, we focus on $\mathrm{SU}(6)$ Yang--Mills theory at a lattice spacing for which conventional methods associated to the decorrelation of the topological charge have an unbearable computational cost. We adopt the recently proposed $paralleltemperingonboundaryconditions$ algorithm, which has been shown to remove systematic effects related to topological freezing, and compute glueball masses with a typical accuracy of $2-5\%$. We observe no sizeable systematic effect in the mass of the first lowest-lying glueball states, with respect to calculations performed at nearly-frozen topological sector.

    ↳ hep-lathep-phhep-thPLB(2022)·53 citations
26. 26*

    Superradiant evolution of the shadow and photon ring of Sgr A${}^{\star }$

    Yifan Chen🇨🇳 · Rittick Roy🇨🇳 · Sunny Vagnozzi🇬🇧 · Luca Visinelli🇨🇳

    Ultralight bosons can affect the dynamics of spinning black holes (BHs) via superradiant instability, which can lead to a time evolution of the supermassive BH shadow. We study prospects for witnessing the superradiance-induced BH shadow evolution, considering ultralight vector and tensor fields. We introduce two observables sensitive to the shadow time-evolution: the shadow drift, and the variation in the azimuthal angle lapse associated to the photon ring autocorrelation. The two observables are shown to be highly complementary, depending on the observer's inclination angle. Focusing on the supermassive object Sgr A${}^{\star }$ we show that both observables can vary appreciably over human timescales of a few years in the presence of superradiant instability, leading to signatures which are well within the reach of the Event Horizon Telescope for realistic observation times (but benefiting significantly from extended observation periods), and paving the way towards probing ultralight bosons in the $\sim 10^{-17}\mathrm{eV}$ mass range.

    ↳ astro-ph.HEgr-qchep-phPRD(2022)·150 citations
27. 27*

    Non-Invertible Chiral Symmetry and Exponential Hierarchies

    Clay Cordova🇺🇸 · Kantaro Ohmori🇯🇵

    We elucidate the fate of classical symmetries which suffer from abelian Adler-Bell-Jackiw anomalies. Instead of being completely destroyed, these symmetries survive as non-invertible topological global symmetry defects with worldvolume anyon degrees of freedom that couple to the bulk through a magnetic one-form global symmetry as in the fractional hall effect. These non-invertible chiral symmetries imply selection rules on correlation functions and arise in familiar models of massless quantum electrodynamics and models of axions (as well as their non-abelian generalizations). When the associated bulk magnetic one-form symmetry is broken by the propagation of dynamical magnetic monopoles, the selection rules of the non-invertible chiral symmetry defects are violated non-perturbatively. This leads to technically natural exponential hierarchies in axion potentials and fermion masses.

    ↳ hep-thhep-phPRX(2023)·267 citations
28. 28*

    Doubly peaked induced stochastic gravitational wave background : Testing baryogenesis from primordial black holes

    Nilanjandev Bhaumik🇮🇳 · Anish Ghoshal🇵🇱 · Marek Lewicki🇵🇱

    Hawking evaporation of primordial black holes (PBHs) can facilitate the generation of matter-antimatter asymmetry. We focus on ultra-low mass PBHs that briefly dominate the universe and evaporate before the big bang nucleosynthesis. We propose a novel test of this scenario by detecting its characteristic doubly peaked gravitational wave (GW) spectrum in future GW observatories. Here the first order adiabatic perturbation from inflation and from the isocurvature perturbations due to PBH distribution, source tensor perturbations in second-order and lead to two peaks in the induced GW background. These resonant peaks are generated at the beginning of standard radiation domination in the presence of a prior PBH-dominated era. This unique GW spectral shape would provide a smoking gun signal of non-thermal baryogenesis from evaporating PBHs, which is otherwise impossible to test in laboratory experiments due to the very high energy scales involved or the feeble interaction of the dark sector with the visible sector.

    ↳ astro-ph.COgr-qchep-phJHEP(2022)·99 citations
29. 29*

    An Effective Bias Expansion for 21 cm Cosmology in Redshift Space

    Wenzer Qin🇺🇸 · Katelin Schutz🇨🇦 · Aaron Smith🇺🇸 · Enrico Garaldi🇩🇪 · Rahul Kannan🇺🇸 · Tracy R. Slatyer🇺🇸 · Mark Vogelsberger🇺🇸

    A near-future detection of the 21cm signal from the epoch of reionization will provide unique opportunities to probe the underlying cosmology, provided that such cosmological information can be extracted with precision. To this end, we further develop effective field theory (EFT) inspired techniques for the 21cm brightness temperature field during the epoch of reionization, incorporating renormalized bias and a treatment of redshift space distortions. Notably, we confirm that in redshift space, measures of the 21cm brightness, e.g the power spectrum, should have irreducible contributions that lack a bias coefficient and therefore contain direct, astrophysics-free information about the cosmological density field; in this work, we study this effect beyond linear order. To validate our theoretical treatment, we fit the predicted EFT Fourier-space shapes to the THESAN suite of hydrodynamical simulations of reionization at the field level, where the considerable number of modes prevents overfitting. We find agreement at the level of a few percent between the 21cm power spectrum from the EFT fits and simulations over the wavenumber range $k\lesssim 0.8$ h/Mpc and neutral fraction $x_{\mathrm{HI}}\gtrsim 0.4$, which is imminently measurable by the Hydrogen Epoch of Reionization Array (HERA) and future experiments. The ability of the EFT to describe the 21cm signal extends to simulations that have different astrophysical prescriptions for reionization as well as simulations with interacting dark matter.

    ↳ astro-ph.COhep-phPRD(2022)·32 citations
30. 30*

    From Rotating to Charged Black Holes and Back Again

    Lars Aalsma🇺🇸 · Gary Shiu🇺🇸

    The mild form of the Weak Gravity Conjecture (WGC) requires higher derivative corrections to extremal charged black holes to increase their charge-to-mass ratio. This allows decay via emission of a smaller extremal black hole. In this paper, we investigate if similar constraints hold for extremal rotating black holes. We do so by considering the leading higher derivative corrections to the four-dimensional Kerr black hole and five-dimensional Myers-Perry black hole. We use a known mapping of these rotating solutions to a four-dimensional non-rotating dyonic Kaluza-Klein black hole and impose the WGC on this charged solution. Going back again to the rotating solutions, this fixes the sign of the corrections to the rotating extremality bounds. The sign of the corrections is non-universal, depending on the black hole under consideration. We argue that this is not at odds with black hole decay, because of the presence of a superradiant instability that persists in the extremal limit. When this instability is present, the WGC is implied for the four-dimensional charged black hole.

    ↳ hep-thgr-qchep-phJHEP(2022)·18 citations
31. 31*

    A perfect fluid hydrodynamic picture of domain wall velocities at strong coupling

    Romuald A. Janik🇵🇱 · Matti Jarvinen🇰🇷 · Hesam Soltanpanahi🇵🇱 · Jacob Sonnenschein🇮🇱

    We show that for a range of strongly coupled theories with a first order phase transition, the domain wall or bubble velocity can be expressed in a simple way in terms of a perfect fluid hydrodynamic formula, and thus in terms of the equation of state. We test the predictions for the domain wall velocities using the gauge/gravity duality.

    ↳ hep-thhep-phPRL(2022)·35 citations
32. 32*

    Double Hawking temperature: from black hole to de Sitter

    G.E. Volovik🇫🇮

    The double Hawking temperature $T=2T_H$ appears in some approaches to the Hawking radiation, when the radiation is considered in terms of the quantum tunneling. We consider the origin of such temperature for the black hole horizon and also for the cosmological horizon in de Sitter spacetime. In case the black hole horizon, there are two contributions to the tunneling process of radiation, each being governed by the temperature $T=2T_H$. These processes are coherently combined to produce the radiation with the Hawking temperature $T_H$. This can be traditionally interpreted as the pair creation of two entangled particles, of which one goes towards the centre of the black hole, while the other one escapes from the black hole. In case of the cosmological horizon, the temperature $T=2T_H$ is physical. While the creation of the entangled pair is described by the Hawking temperature, the de Sitter spacetime allows for the another process, in which only single (non-entangled) particle inside the cosmological horizon is created. This process is characterized by the local temperature $T=2T_H$. Such single particle process takes place also outside the black hole horizon, but it is exponentially suppressed.

    ↳ gr-qchep-phUniverse(2022)·8 citations
33. 33*

    Notes on the experimental observation of the Unruh effect

    Morgan H. Lynch🇮🇱

    The incorporation of classical general relativity into quantum field theory yields a surprising result -- thermodynamic particle production. One such phenomenon, known as the Unruh effect, causes empty space to effervesce a thermal bath of particles when viewed by an observer undergoing uniformly accelerated motion. These systems will have a Rindler horizon which produces this Unruh radiation at the Fulling-Davies-Unruh temperature. For accelerated charges, the emission and absorption of this radiation will imprint the FDU temperature on photons emitted in the laboratory. Each of these photons will also change the Rindler horizon in accordance with the Bekenstein-Hawking area-entropy law. In this essay, we will discuss these aspects of acceleration-induced thermality which have been experimentally observed in a high energy channeling experiment carried out by CERN-NA63.

    ↳ gr-qchep-phhep-th3 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.