Fri·Sep 11, 2020Friday·September 11, 2020

1. 01*

   Elastic positivity vs extremal positivity bounds in SMEFT: a case study in transversal electroweak gauge-boson scatterings

   Kimiko Yamashita🇨🇳 · Cen Zhang🇨🇳 · Shuang-Yong Zhou🇨🇳

   The positivity bounds, derived from the axiomatic principles of quantum field theory (QFT), constrain the signs of Wilson coefficients and their linear combinations in the Standard Model Effective Field Theory (SMEFT). The precise determination of these bounds, however, can become increasingly difficult as more and more SM modes and operators are taken into account. We study two approaches that aim at obtaining the full set of bounds for a given set of SM fields: 1) the traditional elastic positivity approach, which exploits the elastic scattering amplitudes of states with arbitrarily superposed helicities as well as other quantum numbers, and 2) the newly proposed extremal positivity approach, which constructs the allowed coefficient space directly by using the extremal representation of convex cones. Considering the electroweak gauge-bosons as an example, we demonstrate how the best analytical and numerical positivity bounds can be obtained in several ways. We further compare the constraining power and the efficiency of various approaches, as well as their applicability to more complex problems. While the new extremal approach is more constraining by construction, we also find that it is analytically easier to use, numerically much faster than the elastic approach, and much more applicable when more SM particle states and operators are taken into account. As a byproduct, we provide the best positivity bounds on the transversal quartic-gauge-boson couplings, required by the axiomatic principles of QFT, and show that they exclude $\approx 99.3\%$ of the parameter space currently being searched at the LHC.

   hep-phhep-exhep-thJHEP(2021)·72 citations
2. 02*

   Probing lepton number violating interactions in rare kaon decays

   Frank F. Deppisch🇬🇧 · Kåre Fridell🇩🇪 · Julia Harz🇩🇪

   We investigate the possibility to probe lepton number violating (LNV) operators in the rare kaon decay $K\to \pi \nu \nu$. Performing the analysis in the Standard Model effective field theory with only light active Majorana neutrinos, we determine the current limits on the corresponding LNV physics scale from the past E949 experiment at BNL as well as the currently operating experiments NA62 at CERN and KOTO at J-PARC. We focus on the specific signature of scalar currents in $K\to \pi \nu \nu$ arising from the LNV nature of the operators and study the effect on the experimental sensitivity, stressing the need for dedicated searches for beyond the SM currents. We find that the rare kaon decays probe high operator scales ${\Lambda }_{\text{LNV}}\approx 15$ to $20$ TeV in different quark and neutrino flavours compared to neutrinoless double beta decay. Furthermore, we comment that the observation of LNV in kaon decays can put high-scale leptogenesis under tension. Finally, we discuss the connection with small radiatively generated neutrino masses and show how the severe constraints therefrom can be evaded in a minimal ultraviolet-complete scenario featuring leptoquarks.

   hep-phJHEP(2020)·53 citations
3. 03*

   $J/\psi$-$p$ Scattering Length from the Total and Differential Photoproduction Cross Sections

   Lubomir Pentchev (Thomas Jefferson National Accelerator Facility, Newport News, Virginia, USA)🇺🇸 · Igor I. Strakovsky (The George Washington University, Washington, D.C., USA)🇺🇸

   The $J/\psi$-$p$ scattering length, ${\alpha }_{J/\psi p}$, can be extracted from the $J/\psi$ photoproduction cross section near threshold using the Vector Meson Dominance (VMD) model to relate the reaction $\gamma p\to J/\psi p$ to $J/\psi p\to J/\psi p$. Such estimates based on experimental data result in values for $|{\alpha }_{J/\psi p}|$, which are much lower than most of the theoretical predictions. In this work, we study the relations between the different results, depending on the use of the total or the differential cross sections, and the method of extrapolating the data to threshold in the case of a low-statistics data sample, such as the near threshold $J/\psi$ photoproduction dataset. We estimate a range for $|{\alpha }_{J/\psi p}|$ of $0.003$ to $0.025$~fm as extracted from experimental data within the VMD model and discuss possible reasons for such lower values compared to the theoretical results.

   hep-phhep-exnucl-exnucl-thEPJA(2021)·37 citations
4. 04*

   The State of the Art in Constraining Axion-to-Nucleon Coupling and Non-Newtonian Gravity from Laboratory Experiments

   V. M. Mostepanenko🇷🇺 · G. L. Klimchitskaya🇷🇺

   Constraints on the Yukawa-type corrections to Newton's gravitational law and on the coupling constant of axionlike particles to nucleons obtained from different laboratory experiments are reviewed and compared. The constraints on non-Newtonian gravity under discussion cover the wide interaction range from nanometers to millimeters and follow from the experiments on neutron scattering, measuring the Casimir force and Cavendish-type experiments. The constraints on the axion-to-nucleon coupling constant following from the magnetometer measurements, Cavendish-type experiments, Casimir physics, and experiments with beams of molecular hydrogen are considered which refer to the region of axion masses from $10^{-10}$ eV to 200 eV. Particular attention is given to the recent constraints obtained from measuring the Casimir force at nanometer separation distance between the test bodies. Several proposed experiments focused on constraining the non-Newtonian gravity, axionlike particles and other hypothetical weakly interacting particles, such as chameleons and symmetrons, are discussed.

   hep-phUniverse(2020)·37 citations
5. 05*

   Non-Abelian axial anomaly, axial-vector duality, and the pseudoscalar glueball

   Sergey Khlebtsov🇷🇺 · Yaroslav Klopot🇷🇺 · Armen Oganesian🇷🇺 · Oleg Teryaev🇷🇺

   We generalize the dispersive approach to axial anomaly by A.D. Dolgov and V.I. Zakharov to a non-Abelian case with arbitrary photon virtualites. We derive the anomaly sum rule for the singlet current and obtain the ${\pi }^0,\eta ,{\eta }^{\prime }\to \gamma {\gamma }^{\ast }$ transition form factors. Using them, we established the behavior of a nonperturbative gluon matrix element $⟨0|G\tilde{G}|\gamma {\gamma }^{\ast }(q^2)⟩$ in both spacelike and timelike regions. We found a significant contribution of the non-Abelian axial anomaly to the processes with one virtual photon, comparable to that of the electromagnetic anomaly. The duality between the axial and the vector channels was observed: the values of duality intervals and mixing parameters in the axial channel were related to vector resonances' masses and residues. The possibility of a light pseudoscalar glueball-like state is conjectured.

   hep-phhep-thPRD(2021)·9 citations
6. 06*

   Qualities of axion and LSP in Pati-Salam unification with $Z_4^R\times Z_N$ symmetry

   Junichiro Kawamura🇺🇸 · Stuart Raby🇺🇸

   In this paper we construct supersymmetric Pati-Salam (PS) models containing the minimal supersymmetric standard model and an invisible axion. The models include two discrete symmetries, ${\mathbb{Z}}_4^R\times {\mathbb{Z}}_N$, which maintain the $quality$ of the accidental Peccei-Quinn (PQ) symmetry and thus the solution to the strong CP problem. We require that the discrete anomaly conditions are satisfied for both ${\mathbb{Z}}_4^R\times G_{\mathrm{PS}}^2$ and ${\mathbb{Z}}_N\times G_{\mathrm{PS}}^2$. The vacuum expectation value of the PQ field spontaneously breaks all the discrete symmetries. R-parity is violated if any of the PQ field(s) has an odd charge under ${\mathbb{Z}}_4^R$. We present two explicit models which we refer to as a minimal model where R-parity violation is extremely suppressed, and a non-minimal model where R-parity violation is significant. In the latter model, the neutralino becomes unstable even if it is the Lightest Supersymmetric Particle (LSP), and, in addition, there are new low-energy vector-like states. In both examples, R-parity violation is sufficiently suppressed such that the proton is stable.

   hep-phhep-thPRD(2021)·8 citations
7. 07*

   Trimaximal neutrino mixing from scotogenic $A_4$ family symmetry

   Gui-Jun Ding🇨🇳 · Jun-Nan Lu🇨🇳 · Jose W. F. Valle🇪🇸

   We propose a flavour theory of leptons implementing an $A_4$ family symmetry. Our scheme provides a simple way to derive trimaximal neutrino mixing from first principles, leading to simple and testable predictions for neutrino mixing and CP violation. Dark matter mediates neutrino mass generation, as in the simplest scotogenic model.

   hep-phPLB(2021)·26 citations
8. 08*

   In-medium transverse momentum broadening effects on di-jet observables

   Martin Rohrmoser · Krzysztof Kutak · Andreas van Hameren · Wiesław Płaczek · Konrad Tywoniuk

   Heavy ion collisions at high energies can be used as an interesting way to recreate and study the medium of the quark-gluon plasma (QGP). We particularly investigate the jets produced in hard binary collisions and their interactions with a tentative medium. These jets were obtained numerically from the Monte-Carlo simulations of hard collisions using the KATIE-algorithm [1], where parton momenta within the colliding nucleons were describe by means of unintegrated parton distribution functions (uPDF). We evolved these jets within a medium that contains both, transverse kicks (yielding a broadening in momentum transvers to the jet-axis) as well as medium induced radiation within the MINCAS-algorithm [2] following the works of [3,4]. We produce qualitative results for the decorrelation of dijets. In particular, we study deviations from a transverse momentum broadening that follows a Gaussian distribution. [1] A. van Hameren, Comput.Phys.Commun. 224 (2018) 371-380 [2] K. Kutak, W. Płaczek, R. Straka, Eur.Phys.J. C79 (2019) no.4, 317 [3] J.-P. Blaizot, F. Dominguez, E. Iancu, Y. Mehtar-Tani, JHEP 1301 (2013) 143 [4] J.-P. Blaizot, F. Dominguez, E. Iancu, Y. Mehtar-Tani, JHEP 1406 (2014) 075

   hep-phPoS(2021)·1 citation
9. 09*

   Sensitivity of strange quark polarization to flavor SU(3) symmetry breaking

   Ali Khorramian🇮🇷 · Elliot Leader🇬🇧 · Dimiter Stamenov🇧🇬 · Amir Shabanpour🇮🇷

   The polarized strange quark puzzle concerns the fact that the polarized strange quark density extracted from polarized inclusive deep inelastic scattering data is significantly negative, whereas it is zero or slightly positive when extracted from a combined analysis of polarized semi-inclusive and inclusive deep inelastic data. SU(3) flavor symmetry, which, it is generally accepted, is not an exact symmetry, plays an important role in the inclusive analysis, and all the extracted polarized quark densities depend, to some extent, on the level of symmetry breaking introduced. But by far the most sensitive to the breaking is the strange quark density. In this paper we present a NLO QCD analysis of the world data on polarized inclusive DIS data on protons, neutrons and deuterons, including the final JLAB CLAS/EG1b data on the proton and deuteron, and study the sensitivity of the strange quark polarization to the breaking of flavor SU(3).

   hep-phhep-exPRD(2021)·7 citations
10. 10*

    Multiplicity dependence of (multi-)strange baryons in the canonical ensemble with phase shift corrections

    Jean Cleymans🇿🇦 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱 · Natasha Sharma🇮🇳

    The increase in strangeness production with charged particle multiplicity, as seen by the ALICE collaboration at CERN in p-p, p-Pb and Pb-Pb collisions, is investigated in the hadron resonance gas model taking into account interactions among hadrons using S-matrix corrections based on known phase shift analyses. Strangeness conservation is taken into account in the framework of the canonical strangeness ensemble. A very good description is obtained for the variation of the strangeness content in the final state as a function of the number of charged hadrons in the mid-rapidity region using the same fixed temperature value as obtained in the most central Pb-Pb collisions. It is shown that the number of charged hadrons is linearly proportional to the volume of the system. For small multiplicities the canonical ensemble with local strangeness conservation restricted to mid-rapidity leads to a stronger suppression of (multi-)strange baryons than seen in the data. This is compensated by introducing a global conservation of strangeness in the whole phase-space which is parameterized by the canonical correlation volume larger than the fireball volume at the mid-rapidity. The results on comparing the hadron resonance gas model with and without S-matrix corrections, are presented in detail. It is shown that the interactions introduced by the phase shift analysis via the S-matrix formalism are essential for a better description of the yields data.

    hep-phhep-exPRC(2021)·57 citations
11. 11*

    Precise Values of Running Quark and Lepton Masses in the Standard Model

    Guo-yuan Huang🇨🇳 · Shun Zhou🇨🇳

    The precise values of the running quark and lepton masses $m_f^{}(\mu )$, which are defined in the modified minimal subtraction scheme ($\overline{\mathrm{MS}}$) with $\mu$ being the renormalization scale and the subscript $f$ referring to all the charged fermions in the Standard Model (SM), are very useful for the model building of fermion masses and flavor mixing and for the precision calculations in the SM or its new-physics extensions. In this paper, we calculate the running fermion masses by taking account of the up-to-date experimental results collected by Particle Data Group and the latest theoretical higher-order calculations of relevant renormalization-group equations and matching conditions in the literature. The emphasis is placed on the quantitative estimation of current uncertainties on the running fermion masses, and the linear error propagation method is adopted to quantify the uncertainties, which has been justified by the Monte-Carlo simulations. We identify two main sources of uncertainties, i.e., one from the experimental inputs and the other from the truncations at finite-order loops. The correlations among the uncertainties of running parameters can be remarkable in some cases. The final results of running fermion masses at several representative energy scales are tabulated for further applications.

    hep-phPRD(2021)·89 citations
12. 12*

    Top Rare Decays t-> cV in the Mirror Twin Higgs Models

    Su-Ya Bie🇨🇳 · Guo-Li Liu🇨🇳 · Wenyu Wang🇨🇳

    The decay t -> c V (V=\gamma, Z, g) process in the mirror twin Higgs models with the colorless top partners are studied in this paper. We found that the branching ratios of these decays can in some parameter spaces alter the standard model expectations greatly and may be detectable according to the currently precision electroweak measurements. Thus, the constraints on the model parameters may be obtained from the branching fraction of the decay processes, which may serve as a robust detection to this new physics model.

    hep-phCPC(2021)·5 citations
13. 13*

    Bound States of Right-handed Sneutrino Dark Matter

    A. Elsheshtawy · S. Khalil🇪🇬

    The relic abundance of the lightest right-handed sneutrino dark matter in supersymmetric B-L extension of the standard model is revisited. We argue that it can form a bound state through the exchange of light B-L Higgs boson and a large non-perturbative Sommerfeld effect is obtained. We emphasized that with this effect the relic abundance of right-handed sneutrino will lie within the observational limits and the right-handed sneutrino will remain a viable dark matter candidate of mass order up to 1.5 TeV.

    hep-ph0 citations
14. 14*

    Associated Higgs + jet(s) production at the LHC and CCFM gluon dynamics in a proton

    A.V. Lipatov🇷🇺 · M.A. Malyshev🇷🇺

    We consider the associated production of Higgs boson and hadronic jet(s) in $pp$ collisions at the LHC for the first time using the $k_T$-factorization approach. Our analysis is based on the off-shell gluon-gluon fusion subprocess, where non-zero transverse momenta of initial gluons are taken into account and covers $H\to \gamma \gamma$, $H\to Z{Z}^{\ast }\to 4l$ (with $l=e,\mu$) and $H\to W^{+}{W}^{-}\to e^{\pm }{\mu }^{\mp }\nu \bar{\nu }$ decay channels. The transverse momentum dependent (TMD) gluon densities in a proton are taken from Catani-Ciafaloni-Fiorani-Marchesini evolution equation. To simulate the kinematics of the produced jets the TMD parton shower implemented into the Monte-Carlo event generator \textsc{cascade} is applied. The comparison of our results with the latest experimental data taken by the CMS and ATLAS Collaborations at $\sqrt{s}=8$ and $13$ TeV and conventional higher-order perturbative QCD calculations is presented. We highlight observables, which are sensitive to the TMD gluon densities in a proton.

    hep-phPRD(2021)·5 citations
15. 15*

    Simulation of the neutron-tagged deep inelastic scattering at EicC

    Gang Xie🇨🇳 · Mengyang Li🇨🇳 · Chengdong Han🇨🇳 · Rong Wang🇨🇳 · Xurong Chen🇨🇳

    Measuring the pionic structure function is of high interests as it provides a new area for understanding the strong interaction among quarks and testing the QCD predictions. To this purpose, we investigate the feasibility and the expected impacts of a possible experiment on EicC. We show the simulation results on the statistical precision of an EicC measurement, based on the model of leading neutron tagged DIS process and the parton distribution functions of the pion from JAM18 global analysis. The simulation shows that at EicC, the kinematics cover $x_{\pi }$ range from 0.01 to 1, and $Q^2$ range from 1 GeV${}^2$ to 50 GeV${}^2$, within the acceptable statistical uncertainty. Assuming an integrated luminosity of 50 fb${}^{-1}$, in the low-$Q^2$ region ($<10$ GeV${}^2$), the MC data show that the suggested measurement in the whole $x_{\pi }$ range reaches very high precision ($<3$\%). To perform such an experiment, only the addition of a far-forward neutron calorimeter is needed.

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

    Early Time Dynamics and the Bulk

    Bin Wu🇨🇭

    Deciphering the origin of collective phenomena in small colliding systems is one of contemporary focuses in heavy-ion physics. It entails penetrating the barrier between two previously separated research topics: thermalization/hydrodynamization and phenomenological studies of collectivity. I first review some recent progress in understanding thermalization/hydrodynamization in large colliding systems, centralized on bottom-up thermalization. Then, using a simple kinetic theory I demonstrate how the investigation of hydrodynamization is intertwined with the study of flow in small colliding systems. Connections of these studies to "hard probes" are also commented where possible.

    hep-phhep-exnucl-exnucl-thPoS(2021)·1 citation
17. 17*

    Impact of high energy beam tunes on the sensitivities to the standard unknowns at DUNE

    Jogesh Rout🇮🇳 · Samiran Roy🇮🇳 · Mehedi Masud🇮🇳 · Mary Bishai🇺🇸 · Poonam Mehta🇮🇳

    Even though neutrino oscillations have been conclusively established, there are a few unanswered questions pertaining to leptonic Charge Parity violation (CPV), mass hierarchy (MH) and ${\theta }_{23}$ octant degeneracy. Addressing these questions is of paramount importance at the current and future neutrino experiments including the Deep Underground Neutrino Experiment (DUNE) which has a baseline of 1300 km. In the standard mode, DUNE is expected to run with a {\textit{low energy}} (LE) tuned beam which peaks around the first oscillation maximum ($2-3$ GeV) (and then sharply falls off as we go to higher energies). However, the wide band nature of the beam available at long baseline neutrino facility (LBNF) allows for the flexibility in utilizing beam tunes that are well-suited at higher energies as well. In this work, we utilize a beam that provides high statistics at higher energies which is referred to as the {\textit{medium energy}} (ME) beam. This opens up the possibility of exploring not only the usual oscillation channels but also the ${\nu }_{\mu }\to {\nu }_{\tau }$ oscillation channel which was otherwise not accessible. Our goal is to find an optimal combination of beam tune and runtime (with the total runtime held fixed) distributed in neutrino and antineutrino mode that leads to an improvement in the sensitivities of these parameters at DUNE. In our analysis, we incorporate all the three channels (${\nu }_{\mu }\to {\nu }_e,{\nu }_{\mu }\to {\nu }_{\mu },{\nu }_{\mu }\to {\nu }_{\tau }$) and develop an understanding of their relative contributions in sensitivities at the level of $\Delta {\chi }^2$. Finally, we obtain the preferred combination of runtime using both the beam tunes as well as neutrino and antineutrino mode that lead to enhanced sensitivity to the current unknowns in neutrino oscillation physics i.e., CPV, MH and ${\theta }_{23}$ octant.

    hep-phhep-exPRD(2020)·18 citations
18. 18*

    Revisit the tetraquark candidates in the $J/\psi J/\psi$ mass spectrum

    Zhi-Gang Wang🇨🇳

    In this article, we introduce a relative P-wave to construct the doubly-charm axialvector diquark operator, then take the doubly-charm axialvector (anti)diquark operator as the basic constituent to construct the scalar and tensor tetraquark currents to study the scalar, axialvector and tensor fully-charm tetraquark states with the QCD sum rules. We observe that the ground state $\tilde{A}\tilde{A}$ type tetraquark states and the first radial excited states of the $AA$ type tetraquark states have almost degenerated masses, where the $\tilde{A}$ and $A$ stand for the diquark operators with and without the relative P-wave respectively, the broad structure above the $J/\psi J/\psi$ threshold maybe consist of several diquark-antidiquark type fully-charm tetraquark states.

    hep-phInt.J.Mod.Phys.A(2021)·45 citations
19. 19*

    On holographic relation between radial meson trajectories and deconfinement temperature

    S. S. Afonin🇷🇺 · A. D. Katanaeva🇪🇸

    The interrelation between the deconfinement temperature of hadron medium and parameters of radial Regge trajectories within the bottom-up holographic models for QCD is scrutinized. We show that the lattice data on the deconfinement temperature can yield a powerful restriction on the spectrum of excited mesons and glueballs within the framework of holographic approach. The best phenomenological agreement and theoretical self-consistency are achieved if the scalar meson $f_0(1500)$ is considered as the lightest glueball.

    hep-ph18th International Conference on Hadron S…·2 citations
20. 20*

    Regge trajectories in light and heavy mesons: the pattern of appearances and possible dynamical explanations

    S. S. Afonin🇷🇺

    I briefly review the Regge approach to the hadron spectrum and advocate a dynamical emergence of principal quantum number in the known spectrum of light non-strange mesons. Further it is shown how the linear radial trajectories with universal slope can be extended to heavy quarkonia and a qualitative string interpretation is given. After that I discuss a recently proposed non-string model leading to a natural appearance of linear Regge trajectories and explaining many mass relations.

    hep-ph18th International Conference on Hadron S…·5 citations
21. 21*

    Crisis on Infinite Earths: Short-lived de Sitter Vacua in the String Theory Landscape

    Heliudson Bernardo🇨🇦 · Suddhasattwa Brahma🇨🇦 · Keshav Dasgupta🇨🇦 · Radu Tatar🇬🇧

    We construct purely non-perturbative anti-de Sitter vacua in string theory which, on uplifting to a de Sitter (dS) one, have a decay time many orders of magnitude smaller than those of standard constructions, such as the KKLT and LVS scenarios. By virtue of being constructed purely from non-perturbative terms, these vacua avoids certain obstructions plaguing other constructions of dS in string theory. This results in a new class of phenomenological dS vacua in string theory with novel distinctive characteristics such as having two maxima. After examining whether these uplifted dS vacua obey the TCC, we revisit some old problems of realization of dS space as a vacuum. We find that not only is it phenomenologically hard to construct TCC-compatible vacua, but also inherent temporal dependences of the degrees of freedom generically arise in such constructions, amongst other issues. This reinforces the idea that dS, if it exists in string theory, should be a Glauber-Sudarshan state and not a vacuum.

    ↳ hep-thgr-qchep-phJHEP(2021)·30 citations
22. 22*

    Gauge independence of pion masses in a magnetic field within the Nambu--Jona-Lasinio model

    Jianing Li🇨🇳 · Gaoqing Cao🇨🇳 · Lianyi He🇨🇳

    We investigate the properties of neutral and charged pions in a constant background magnetic field mainly at zero temperature within the Nambu--Jona-Lasinio model. In the previous calculations, the Ritus method, involving Schwinger phases in a fixed gauge, was employed within the momentum-space random phase approximation (RPA)~[Phys. Lett. B $\text{782}$, 155-161 (2018)]. However, gauge invariance of the charged pion masses has not yet been examined. In this work, by adopting the linear response theory based on the imaginary-time path integral formalism, we derive the correlation functions for pions in the coordinate space, where the corresponding Schwinger phases show up automatically. At sufficiently large imaginary time $\tau$, the meson correlation function approaches an exponential form $\sim \exp (-E_{\mathrm{G}}\tau )$, where $E_{\mathrm{G}}$ is the ground-state energy of the one-meson state and hence determined as the meson mass. Furthermore, we show that the mass of the charged pions is gauge independent, i.e., independent of the choice of the vector potential for the magnetic field. Actually, we also find that the momentum-space RPA is equivalent to the imaginary-time method used here.

    ↳ nucl-thhep-phPRD(2021)·29 citations
23. 23*

    The Clustering Evolution of Primordial Black Holes

    V. De Luca🇨🇭 · V. Desjacques🇮🇱 · G. Franciolini🇨🇭 · A. Riotto🇨🇭

    Primordial black holes might comprise a significant fraction of the dark matter in the Universe and be responsible for the gravitational wave signals from black hole mergers observed by the LIGO/Virgo collaboration. The spatial clustering of primordial black holes might affect their merger rates and have a significant impact on the constraints on their masses and abundances. We provide some analytical treatment of the primordial black hole spatial clustering evolution, compare our results with some of the existing N-body numerical simulations and discuss the implications for the black hole merger rates. If primordial black holes contribute to a small fraction of the dark matter, primordial black hole clustering is not relevant. On the other hand, for a large contribution to the dark matter, we argue that the clustering may increase the late time Universe merger rate to a level compatible with the LIGO/Virgo detection rate. As for the early Universe merger rate of black hole binaries formed at primordial epochs, clustering alleviates the LIGO/Virgo constraints, but does not evade them.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·140 citations
24. 24*

    Analysis of published data of electron capture in 7Be in the search for a heavy neutrino in the mass range under 800 keV

    N.A. Likhovid🇷🇺 · V.S. Pantuev🇷🇺

    We present a reanalysis of the experimental data of electron capture in ${}^7$Be embedded in Ta which have been published by other authors. Our goal is to set upper limits on a mixture of electron neutrino with a possible right-handed heavy neutrino in the 150--800 keV mass range. In the published experiment a ${}^7$Li recoil energy spectrum in the 20--200 eV range was measured. In case of electron capture with emission of a heavy neutrino, the recoil spectrum should be shifted to the lower energies. We search for an additional Gauss-shaped structure with the same energy width as the main K-shell transition peak. For this we digitize the published spectrum curve, find the energy resolution, calculate the moving sum of the events along the spectrum in the energy interval of about 3 sigma of energy resolution. Then we use the statistical error of this sum to exclude at some level the appearance of an additional peak. Finally, we present the upper limits at a 95\% confidence level on electron neutrino -- heavy neutrino mixing element, $U^2$, in the mass matrix. New upper limits are at least one order of magnitude lower than the existing data in 300--800 keV mass range.

    ↳ hep-exhep-phJETP Lett.(2021)·1 citation
25. 25*

    Global polarization effect and spin-orbit coupling in strong interaction

    Jian-Hua Gao🇨🇳 · Zuo-Tang Liang🇨🇳 · Qun Wang🇨🇳 · Xin-Nian Wang🇨🇳

    In non-central high energy heavy ion collisions the colliding system posses a huge orbital angular momentum in the direction opposite to the normal of the reaction plane. Due to the spin-orbit coupling in strong interaction, such huge orbital angular momentum leads to the polarization of quarks and anti-quarks in the same direction. This effect, known as the global polarization effect, has been recently observed by STAR Collaboration at RHIC that confirms the theoretical prediction made more than ten years ago. The discovery has attracted much attention on the study of spin effects in heavy ion collision. It opens a new window to study properties of QGP and a new direction in high energy heavy ion physics -- Spin Physics in Heavy Ion Collisions. In this chapter, we review the original ideas and calculations that lead to the predictions. We emphasize the role played by spin-orbit coupling in high energy spin physics and discuss the new opportunities and challenges in this connection.

    ↳ nucl-thhep-phLect.Notes Phys.(2021)·39 citations
26. 26*

    Exclusive $J/\psi$ photoproduction off deuteron in d+Au ultra-peripheral collisions at STAR

    Zhoudunming Tu (for the STAR Collaboration)🇺🇸

    Gluon density and its distributions inside nuclei and the parton modification of bounded nucleons inside a nucleus, are some of the main standing problems in nuclear and particle physics. In recent years, ultra-peripheral collisions (UPC) of heavy ions have provided a new way of probing the gluon density, which is based on coherent diffractive vector-meson productions, e.g., $J/\psi$ meson. For heavy ions, e.g., Pb, the gluon density is found to be significantly suppressed through the UPC $J/\psi$ measurement, suggesting a strong gluon shadowing effect in heavy nuclei. In this analysis, we aim to look at a unique set of data taken by the STAR experiment, where $J/\psi$ mesons are photoproduced off the deuteron target with no other particle produced, except for the deuteron or its breakup products. The Zero Degree Calorimeter response with respect to the deuteron dissociation by detecting a beam-rapidity neutron is also investigated and provides additional information about the underlying physics process. The cross section of $J/\psi$ photoproduction in the photon-deuteron system is measured at the photon-nucleon center-of-mass energy $W\sim 25\mathrm{GeV}$, as well as the momentum transfer $t$ dependence cross section, $d\sigma /dt$. Data suggests a wider gluon density distribution than the Hulthen charge density distribution in deuteron.

    ↳ nucl-exhep-exhep-phnucl-thPoS(2021)·3 citations
27. 27*

    The energy-dependent ${\pi }^{+}{\pi }^{+}{\pi }^{+}$ scattering amplitude from QCD

    Maxwell T. Hansen🇨🇭 · Raul A. Briceño🇺🇸 · Robert G. Edwards🇺🇸 · Christopher E. Thomas🇬🇧 · David J. Wilson🇬🇧

    Focusing on three-pion states with maximal isospin (${\pi }^{+}{\pi }^{+}{\pi }^{+}$), we present the first non-perturbative determination of an energy-dependent three-hadron scattering amplitude from first-principles QCD. The calculation combines finite-volume three-hadron energies, extracted using numerical lattice QCD, with a relativistic finite-volume formalism, required to interpret the results. To fully implement the latter, we also solve integral equations that relate an intermediate three-body K matrix to the physical three-hadron scattering amplitude. The resulting amplitude shows rich analytic structure and a complicated dependence on the two-pion invariant masses, represented here via Dalitz-like plots of the scattering rate.

    ↳ hep-lathep-phPRL(2021)·115 citations
28. 28*

    Perturbative aspects of the deconfinement transition -- Physics beyond the Faddeev-Popov model

    Urko Reinosa🇫🇷

    In the case of non-abelian gauge theories, the standard Faddeev-Popov (FP) gauge-fixing procedure in the Landau gauge is known to be incomplete due to the presence of gauge-equivalent field configurations. A widespread belief is that the proper analysis of the low energy properties in this gauge requires the extension of the gauge-fixing procedure beyond the FP recipe. This manuscript reviews various applications of the Curci-Ferrari (CF) model, a phenomenological proposal for such an extension, based on the decoupling properties of Landau gauge correlators as computed on the lattice. We investigate the predictions of the model concerning the deconfinement transition of strongly interacting matter at finite temperature, first in the case of pure Yang-Mills theory and then in the case of heavy-quark Quantum Chromodynamics. We show that most qualitative aspects and also many quantitative features of the deconfinement transition can be accounted for within the CF model, with only one additional parameter, adjusted from comparison to lattice simulations. Moreover, these features emerge in a systematic and controlled perturbative expansion, as opposed to the ill-defined perturbative expansion within the FP model in the infrared. Applications at finite temperature and/or density require one to consider a background extension of the Landau gauge, the so-called Landau-deWitt gauge. The manuscript is also intended as a thorough but pedagogical introduction to these techniques, including the rationale for introducing a background, the role of the Weyl chambers, and the complications that emerge due to the sign problem in the case of a real quark chemical potential. It also investigates the fate of the correlation functions as computed in the CF model and conjectures a specific behavior for the corresponding functions evaluated on the lattice, in the case of the SU(2) gauge group.

    ↳ hep-thhep-lathep-phLect.Notes Phys.(2022)·11 citations
29. 29*

    Probing the multi-scale dynamical interaction between heavy quarks and the QGP using JETSCAPE

    W. Fan🇺🇸 · G. Vujanovic🇺🇸 · A. Angerami🇺🇸 · S. A. Bass🇺🇸 · S. Cao🇺🇸 · Y. Chen🇨🇳 · J. Coleman🇺🇸 · L. Cunqueiro🇺🇸 · T. Dai🇺🇸 · L. Du🇺🇸 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 and 38 other authors

    The dynamics of shower development for a jet traveling through the QGP involves a variety of scales, one of them being the heavy quark mass. Even though the mass of the heavy quarks plays a subdominant role during the high virtuality portion of the jet evolution, it does affect longitudinal drag and diffusion, stimulating additional radiation from heavy quarks. These emissions partially compensate the reduction in radiation from the dead cone effect. In the lower virtuality part of the shower, when the mass is comparable to the transverse momenta of the partons, scattering and radiation processes off heavy quarks differ from those off light quarks. All these factors result in a different nuclear modification factor for heavy versus light flavors and thus for heavy-flavor tagged jets. In this study, the heavy quark shower evolution and the fluid dynamical medium are modeled on an event by event basis using the JETSCAPE Framework. We present a multi-stage calculation that explores the differences between various heavy quark energy-loss mechanisms within a realistically expanding quark-gluon plasma (QGP). Inside the QGP, the highly virtual and energetic portion of the shower is modeled using the MATTER generator, while the LBT generator models the showers induced by energetic and close-to-on-shell heavy quarks. Energy-momentum exchange with the medium, essential for the study of jet modification, proceeds using a weak coupling recoil approach. The JETSCAPE framework allows for transitions, on the level of individual partons, from one energy-loss prescription to the other depending on the parton's energy and virtuality and the local density. This allows us to explore the effect and interplay between the different regimes of energy loss on the propagation and radiation from hard heavy quarks in a dense medium.

    ↳ nucl-thhep-exhep-phPoS(2021)·1 citation
30. 30*

    Gapped Chiral Fermions

    Shlomo S. Razamat🇮🇱 · David Tong🇬🇧

    In principle, there is no obstacle to gapping fermions preserving any global symmetry that does not suffer a 't Hooft anomaly. In practice, preserving a symmetry that is realised on fermions in a chiral manner necessitates some dynamics beyond simple quadratic mass terms. We show how this can be achieved using familiar results about supersymmetric gauge theories and, in particular, the phenomenon of confinement without chiral symmetry breaking. We present simple models that gap fermions while preserving a symmetry group under which they transform in chiral representations. For example, we show how to gap a collection of 4d fermions that carry the quantum numbers of one generation of the Standard Model, but without breaking electroweak symmetry. We further show how to gap fermions in groups of 16 while preserving certain discrete symmetries that exhibit a mod 16 anomaly.

    ↳ hep-thcond-mat.str-elhep-phPRX(2021)·84 citations
31. 31*

    Charting the low-loss region in Electron Energy Loss Spectroscopy with machine learning

    Laurien I. Roest🇳🇱 · Sabrya E. van Heijst🇳🇱 · Louis Maduro🇳🇱 · Juan Rojo🇳🇱 · Sonia Conesa-Boj🇳🇱

    Exploiting the information provided by electron energy-loss spectroscopy (EELS) requires reliable access to the low-loss region where the zero-loss peak (ZLP) often overwhelms the contributions associated to inelastic scatterings off the specimen. Here we deploy machine learning techniques developed in particle physics to realise a model-independent, multidimensional determination of the ZLP with a faithful uncertainty estimate. This novel method is then applied to subtract the ZLP for EEL spectra acquired in flower-like WS${}_2$ nanostructures characterised by a 2H/3R mixed polytypism. From the resulting subtracted spectra we determine the nature and value of the bandgap of polytypic WS${}_2$, finding $E_{\mathrm{BG}}=1.6_{-0.2}^{+0.3}\mathrm{eV}$ with a clear preference for an indirect bandgap. Further, we demonstrate how this method enables us to robustly identify excitonic transitions down to very small energy losses. Our approach has been implemented and made available in an open source Python package dubbed EELSfitter.

    ↳ cond-mat.mtrl-scihep-phUltramicroscopy(2021)·5 citations
32. 32*

    Predictions for production of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$ in isobaric ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV

    Zhi-Lei She🇨🇳 · Gang Chen🇨🇳 · Dai-Mei Zhou🇨🇳 · Liang Zheng🇨🇳 · Yi-Long Xie🇨🇳 · Hong-Ge Xu🇨🇳

    The production of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$, as well as ${}^3\mathrm{H}$, ${}^3\overline{\mathrm{H}}$, ${}^3\mathrm{He}$, and ${}^3\overline{\mathrm{He}}$ are studied in central collisions of isobars ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr at $\sqrt{s_{\mathrm{NN}}}=200$ GeV, using the dynamically constrained phase-space coalescence model and the {\footnotesize PACIAE} model with chiral magnetic effect. The yield, yield ratio, coalescence parameters, and strangeness population factor of (anti-)hypertriton and (anti-)nuclei produced in isobaric ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions are predicted. The (anti-)hypertriton and (anti-)nuclei production is found to be insensitive to the chiral magnetic effects. Experimental data of Cu+Cu, Au+Au and Pb+Pb collisions from RHIC, LHC, and the results of {\footnotesize PACIAE+DCPC} model are presented in the results for comparison.

    ↳ nucl-thhep-phPRC(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.