Wed·Aug 26, 2020Wednesday·August 26, 2020

1. 01*

   Dark Sector Assisted Low Scale Leptogenesis from Three Body Decay

   Debasish Borah🇮🇳 · Arnab Dasgupta🇰🇷 · Devabrat Mahanta🇮🇳

   We study the possibility of realising leptogenesis from three body decay, dark matter (DM) and neutrino mass in a minimal framework. We propose a first of its kind model to implement the idea of leptogenesis from three body decay where CP asymmetry arises from interference of multiple $1\to 3$ diagrams using resummed propagators along with DM. The standard model is extended by three heavy singlet fermions, one scalar singlet and one scalar doublet with appropriate discrete charges. Two of these singlet fermions not only play non-trivial roles in generating light neutrino mass at radiative level in scotogenic fashion, but also act as mediators in three body decay of the third singlet fermion leading to desired CP asymmetry through interference of such diagrams. With just one additional field compared to the minimal scotogenic model, we show that successful leptogenesis can occur at a scale as low as approximately 1 TeV which is much lower than the leptogenesis scale found for minimal scotogenic model. Also, the realisation of this three body decay leptogenesis naturally leads to a two component scalar singlet-doublet dark matter scenario offering a rich phenomenology. Apart from having interesting interplay of different couplings involved in processes related to both leptogenesis and dark matter, the model can also be tested at different experiments due to the existence of its particle spectrum at TeV scale.

   hep-phastro-ph.COPRD(2022)·13 citations
2. 02*

   Reloading the Axion in a 3-3-1 setup

   Alex G. Dias🇧🇷 · Julio Leite🇧🇷 · José W. F. Valle🇪🇸 · Carlos A. Vaquera-Araujo🇲🇽

   We generalize the idea of the axion to an extended electroweak gauge symmetry setup. We propose a minimal axion extension of the Singer-Valle-Schechter (SVS) theory, in which the standard model fits in $\mathrm{SU}(3{)}_{\mathrm{L}}\otimes \mathrm{U}(1{)}_{\mathrm{X}}$, the number of families results from anomaly cancellation, and the Peccei-Quinn (PQ) solution to the strong-CP problem is implemented. Neutrino masses arise from a type-I Dirac seesaw mechanism, suppressed by the ratio of SVS and PQ scales, suggesting the existence of new physics at a moderate SVS scale. Novel features include an enhanced axion coupling to photons when compared to the DFSZ axion, as well as flavour-changing axion couplings to quarks.

   hep-phhep-exhep-thPLB(2020)·25 citations
3. 03*

   Energy of a point-like neutron in an external electromagnetic field

   Jesus Saenz🇺🇸 · Michael Engelhardt🇺🇸 · Roman Höllwieser🇩🇪

   A point-like neutron in an external electromagnetic field experiences a shift in energy that mimicks the effect of an actual structural deformation of an extended neutron, i.e., a proper polarizability. In order to be able to differentiate between the former and the latter, a Foldy-Wouthuysen transformation is constructed which yields the energy shift of a point-like neutron quadratic in the external field in a derivative expansion, generalizing a long-known result for the dipole electric polarizability due to Foldy. The ten leading Foldy contributions to the energy are determined for a zero-momentum neutron. In addition, eliminating the momentum operator in favor of the velocity operator, analogous results are derived for a zero-velocity neutron. In this case, operator ordering ambiguities are encountered that permit only a determination of eight of the ten Foldy terms.

   hep-phhep-latnucl-thPRD(2021)·0 citations
4. 04*

   Regularizing thermo and magnetic contributions within nonrenormalizable theories

   Sidney S. Avancini🇧🇷 · Ricardo L. S. Farias🇧🇷 · Marcus B. Pinto🇧🇷 · Tulio E. Restrepo🇧🇷 · William R. Tavares🇧🇷

   The importance of implementing a proper regularization procedure in order to treat thermo and magnetic contributions within nonrenormalizable theories is investigated. Our study suggests that potential divergences should be isolated into the vacuum and purely magnetic contributions and then regularized while the convergent thermomagnetic contributions should be integrated over the full momentum range. This prescription is illustrated by applying the proper time formalism to the two flavor Polyakov--Nambu--Jona-Lasinio model, whose magnetic field dependent coupling has been recently determined. Observables such as the pressure, magnetization, speed of sound squared, and specific heat evaluated within our scheme are compared with results furnished by other three possible prescriptions. We show that these quantities display a thermomagnetic behavior which is physically more consistent when our scheme is adopted. In particular, we demonstrate that naively regulating the (entangled) vacuum, magnetic and thermomagnetic contributions leads to physically inconsistent results especially at the high temperature domain.

   hep-phhep-thnucl-thPRD(2021)·32 citations
5. 05*

   Constraint Dynamics and RQM Bound States

   Mikhail N. Sergeenko🇧🇾

   Flavored mesons containing quarks of unequal masses are studied. The appropriate tool is the Bethe-Salpeter formalism, but its inherent complexity leads to series of difficulties mostly related to the central role played in it by the relative time or energy. We consider bound states in the spirit of "Constraint Relativistic Quantum Mechanics (RQM)". Interaction of quarks is described by the funnel-type potential with the distant dependent strong coupling, ${\alpha }_s(r)$. Relativistic bound-state problem is formulated with the use of symmetries, energy-momentum conservation laws in Minkowskiy space. Relativistic two-body wave equation with position dependent particle masses is derived and used to describe the flavored mesons. Free particle hypothesis for the bound state is developed: quark and antiquark move as free particles in of the bound system. Solution of the equation for the system in the form of a~standing wave is given. Interpolating complex-mass formula for two exact asymptotic eigenmass expressions is obtained. Mass spectra for some leading-state flavored mesons are calculated.

   hep-ph0 citations
6. 06*

   Magnetic field dependence of nucleon parameters from QCD sum rules

   C. A. Dominguez🇿🇦 · Luis A. Hernández🇲🇽 · Marcelo Loewe🇿🇦 · Cristian Villavicencio🇨🇱 · R. Zamora🇨🇱

   Finite energy QCD sum rules involving nucleon current correlators are used to determine several QCD and hadronic parameters in the presence of an external, uniform, large magnetic field. The continuum hadronic threshold $s_0$, nucleon mass $m_N$, current-nucleon coupling ${\lambda }_N$, transverse velocity $v_{\perp }$, the spin polarization condensate $⟨\bar{q}{\sigma }_{12}q⟩$, and the magnetic susceptibility of the quark condensate ${\chi }_q$, are obtained for the case of protons and neutrons. Due to the magnetic field, and charge asymmetry of light quarks up and down, all the obtained quantities evolve differently with the magnetic field, for each nucleon or quark flavor. With this approach it is possible to obtain the evolution of the above parameters up to a magnetic field strength $eB<1.4$ GeV${}^2$.

   hep-phnucl-thPRD(2020)·16 citations
7. 07*

   The noncommutativity of the static and homogeneous limit of the axial chemical potential in chiral magnetic effect

   Bo Feng🇨🇳 · De-fu Hou🇨🇳 · Hai-cang Ren🇺🇸 · Shuai Yuan🇨🇳

   We study the noncommutativity of different orders of zero energy-momentum limit pertaining to the axial chemical potential in the chiral magnetic effect. While this noncommutativity issue originates from the pinching singularity at one-loop order, it cannot be removed by introducing a damping term to the fermion propagators. The physical reason is that modifying the propagator alone would violate the axial-vector Ward identity and as a result a modification of the longitudinal component of the axial-vector vertex is required, which contributes to CME. The pinching singularity with free fermion propagators was then taken over by the singularity stemming from the dressed axial-vector vertex. We show this mechanism by a concrete example. Moreover, we proved in general the vanishing CME in the limit order that the static limit was taken prior to the homogeneous limit in the light of Coleman-Hill theorem for a static external magnetic field. For the opposite limit that the homogeneous limit is taken first, we show that the nonvanishing CME was a consequence of the nonrenormalizability of chiral anomaly for an arbitrary external magnetic field.

   hep-phPRD(2021)·1 citation
8. 08*

   Possible precise measurements of the $X(3872)$ mass with the $e^{+}{e}^{-}\to {\pi }^0\gamma X(3872)$ and $p\bar{p}\to \gamma X(3872)$ reactions

   Shuntaro Sakai🇨🇳 · Hao-Jie Jing🇨🇳 · Feng-Kun Guo🇨🇳

   It was recently proposed that the $X(3872)$ binding energy, the difference between the $D^0{\bar{D}}^{\ast 0}$ threshold and the $X(3872)$ mass, can be precisely determined by measuring the $\gamma X(3872)$ line shape from a short-distance $D^{\ast 0}{\bar{D}}^{\ast 0}$ source produced at high-energy experiments. Here, we investigate the feasibility of such a proposal by estimating the cross sections for the $e^{+}{e}^{-}\to {\pi }^0\gamma X(3872)$ and $p\bar{p}\to \gamma X(3872)$ processes considering the $D^{\ast 0}{\bar{D}}^{\ast 0}{D}^0/{\bar{D}}^{\ast 0}{D}^{\ast 0}{\bar{D}}^0$ triangle loops. These loops can produce a triangle singularity slightly above the $D^{\ast 0}{\bar{D}}^{\ast 0}$ threshold. It is found that the peak structures originating from the $D^{\ast 0}{\bar{D}}^{\ast 0}$ threshold cusp and the triangle singularity are not altered much by the energy dependence introduced by the $e^{+}{e}^{-}\to {\pi }^0{D}^{\ast 0}{\bar{D}}^{\ast 0}$ and $p\bar{p}\to {\bar{D}}^{\ast 0}{D}^{\ast 0}$ production parts or by considering a finite width for the $X(3872)$. We find that $\sigma (e^{+}{e}^{-}\to {\pi }^0\gamma X(3872))\times \mathrm{Br}(X(3872)\to {\pi }^{+}{\pi }^{-}J/\psi )$ is $\mathcal{O}(0.1\mathrm{fb})$ with the $\gamma X(3872)$ invariant mass integrated from 4.01 to 4.02 GeV and the c.m. energy of the $e^{+}{e}^{-}$ pair fixed at 4.23 GeV. The cross section $\sigma (p\bar{p}\to \gamma X(3872))\times \mathrm{Br}(X(3872)\to {\pi }^{+}{\pi }^{-}J/\psi )$ is estimated to be of $\mathcal{O}(10\mathrm{pb})$. Our results suggest that a precise measurement of the $X(3872)$ binding energy can be done at PANDA.

   hep-phPRD(2020)·18 citations
9. 09*

   Nuclear suppression from coherent $J/\psi$ photoproduction at the Large Hadron Collider

   V. Guzey🇷🇺 · E. Kryshen (St. Petersburg, INP)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (St. Petersburg, INP)🇷🇺

   Using the data on coherent $J/\psi$ photoproduction in Pb-Pb ultraperipheral collisions (UPCs) obtained in Runs 1 and 2 at the Large Hadron Collider (LHC), we determined with a good accuracy the nuclear suppression factor of $S_{Pb}(x)$ in a wide range of the momentum fraction $x$, $10^{-5}\le x\le 0.04$. In the small-$x$ region $x<10^{-3}$, our ${\chi }^2$ fit favors a flat form of $S_{Pb}(x)\approx 0.6$ with approximately a 5% accuracy for $x=6\times 10^{-4}-10^{-3}$ and a 25% error at $x=10^{-4}$. At the same time, uncertainties of the fit do not exclude a slow decrease of $S_{Pb}(x)$ in the small-$x$ limit. At large $x$, $S_{Pb}(x)$ is constrained to better than 10% precision up to $x=0.04$ and is also consistent with the value of $S_{Pb}(x)$ at $⟨x⟩=0.042$, which we extract from the Fermilab data on the $A$ dependence of the cross section of coherent $J/\psi$ photoproduction on fixed nuclear targets. The resulting uncertainties on $S_{Pb}(x)$ are small, which indicates the potential of the LHC data on coherent charmonium photoproduction in Pb-Pb UPCs to provide additional constraints on small-$x$ nPDFs. We explicitly demonstrate this using as an example the EPPS16 and nCTEQ16 nuclear parton distribution functions, whose uncertainties decrease severalfold after the Bayesian reweighting of the discussed UPC data.

   hep-phnucl-exnucl-thPLB(2021)·47 citations
10. 10*

    High energy QCD: multiplicity dependence of quarkonia production

    E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U. and UTFSM)🇮🇱

    In this paper we propose an approach which demonstrates the dependence of quarkoni production on the multiplicity of the accompanying hadrons. Our approach is based on the three gluons fusion mechanism, without assuming the multiplicity dependence of the saturation scale. We show, that we describe the experimental data, which has a dependence that is much steeper than the multiplicity of the hadrons.

    hep-phEPJC(2021)·19 citations
11. 11*

    Hybrid star construction with the extended linear sigma model: preliminary results

    Péter Kovács🇭🇺 · János Takátsy🇭🇺

    The interior of compact stars is usually divided into two major parts, the outer part called crust and the inner part called core. There are several possibilities for the composition of these parts. One is a hybrid star, in which the crust contains nuclear matter, while the inner core contains quark matter. Since at large baryon densities one can work with effective models, and nuclear and quark matter are usually described by different models, some unification of the two parts is needed. We show two different approaches for a composite model and some recent developments in hybrid star constructions using the extended linear sigma model for modeling the quark matter at the core.

    hep-phActa Phys.Polon.Supp.(2021)·2 citations
12. 12*

    $M_{T2}$ as a probe of CP phase in $h\to \tau \tau$ at the LHC

    Abhaya Kumar Swain🇮🇳

    We propose to utilize the transverse mass variable $M_{T2}$ and it's descendant $M_{2Cons}$ for constraining the CP admixture of the tau lepton Yukawa coupling at the LHC. We have considered the tau lepton pair produced from the Higgs boson with each tau decays to a charged pion and a neutrino, ${\tau }^{\pm }\to {\pi }^{\pm }{\nu }_{\tau }$. Recently, for this channel, the LHC has employed the impact parameter method to measure the CP mixing angle of tau lepton Yukawa coupling with large uncertainty. The observables we propose here can be measured in the lab frame without the impact parameter measurement and in turn, give a complementary probe of the CP admixture of tau lepton Yukawa. The CP mixing angle, with our method, can be constrained up to 17${}^{\circ }$ (7${}^{\circ }$) with 300 (3000) $f{b}^{-1}$ of integrated luminosity at the 14 LHC.

    hep-phhep-ex5 citations
13. 13*

    NNLO QCD corrections to leptonic observables in top-quark pair production and decay

    Michal Czakon🇩🇪 · Alexander Mitov🇬🇧 · Rene Poncelet🇬🇧

    We calculate a comprehensive set of spin correlations and differential distributions in top-quark pair production and decay to dilepton final states. This is the first time such a complete study is performed at next-to-next-to leading order in QCD. Both inclusive and fiducial distributions are presented and analyzed. Good agreement between NNLO QCD predictions and data is found. We demonstrate that it is possible to perform high-precision comparisons of fixed-order calculations with fiducial-level data. Subtleties of the top quark definition are raised and clarified. Some of those are found to have a very significant impact on top-quark pair production at absolute threshold.

    hep-phhep-exJHEP(2021)·80 citations
14. 14*

    Molecular picture for the $X_0(2866)$ as a $D^{\ast }{\bar{K}}^{\ast }$ $J^P=0^{+}$ state and related $1^{+},2^{+}$ states

    R. Molina🇪🇸 · E. Oset🇪🇸

    We recall the predictions made ten years ago about a bound state of $J^P=0^{+}$ in $I=0$ of the $D^{\ast }{\bar{K}}^{\ast }$ system, which is manifestly exotic, and we associate it to the $X_0(2866)$ state reported in the recent LHCb experiment. Fine tuning the parameters to reproduce exactly the mass and width of the $X_0(2866)$ state, we report two more states stemming from the same interaction, one with $1^{+}$ and the other with $2^{+}$. For reasons of parity, the $1^{+}$ state cannot be observed in $D\bar{K}$ decay, and we suggest to observe it in the $D^{\ast }\bar{K}$ spectrum. On the other hand, the $2^{+}$ state can be observed in $D\bar{K}$ decay but the present experiment has too small statistics in the region of its mass to make any claim. We note that measurements of the $D^{\ast }\bar{K}$ spectrum and of the $D\bar{K}$ with more statistics should bring important information concerning the nature of the $X_0(2866)$ and related ones that could be observed.

    hep-phPLB(2020)·99 citations
15. 15*

    Lectures on Naturalness, String Landscape and Multiverse

    Arthur Hebecker🇩🇪

    The cosmological constant and electroweak hierarchy problem have been a great inspiration for research. Nevertheless, the resolution of these two naturalness problems remains mysterious from the perspective of a low-energy effective field theorist. The string theory landscape and a possible string-based multiverse offer partial answers, but they are also controversial for both technical and conceptual reasons. The present lecture notes, suitable for a one-semester course or for self-study, attempt to provide a technical introduction to these subjects. They are aimed at graduate students and researchers with a solid background in quantum field theory and general relativity who would like to understand the string landscape and its relation to hierarchy problems and naturalness at a reasonably technical level. Necessary basics of string theory are introduced as part of the course. This text will also benefit graduate students who are in the process of studying string theory at a deeper level. In this case, the present notes may serve as additional reading beyond a formal string theory course.

    ↳ hep-thhep-phLect.Notes Phys.(2021)·58 citations
16. 16*

    New Experimental Constraints in a New Landscape for Composite Dark Matter

    Christopher V. Cappiello🇺🇸 · J. I. Collar🇺🇸 · John F. Beacom🇺🇸

    Certain strongly interacting dark matter candidates could have evaded detection, and much work has been done on constraining their parameter space. Recently, it was shown theoretically that the scattering cross section for $m_{\chi }\gtrsim 1$ GeV pointlike dark matter with a nucleus cannot be significantly larger than the geometric cross section of the nucleus. This realization closes the parameter space for pointlike strongly interacting dark matter. However, strongly interacting dark matter is still theoretically possible for composite particles, with much parameter space open. We set new, wide-ranging limits based on data from a novel detector at the University of Chicago. Backgrounds are greatly suppressed by requiring coincidence detection between two spatially separated liquid-scintillator modules. For dark matter ($v\sim 10^{-3}$c), the time of flight would be $\sim 2\mu \mathrm{s}$, whereas for cosmic rays, it would be $\sim 2\mathrm{ns}$. We outline ways to greatly increase sensitivity at modest costs.

    ↳ hep-exastro-ph.COhep-phPRD(2021)·42 citations
17. 17*

    Eliminating the LIGO bounds on primordial black hole dark matter

    Celine Boehm🇦🇺 · Archil Kobakhidze🇦🇺 · Ciaran A. J. O'Hare🇦🇺 · Zachary S. C. Picker🇦🇺 · Mairi Sakellariadou🇬🇧

    Primordial black holes (PBHs) in the mass range $(30$--$100)M_{\odot }$ are interesting candidates for dark matter, as they sit in a narrow window between microlensing and cosmic microwave background constraints. There are however tight constraints from the binary merger rate observed by the LIGO and Virgo experiments. In deriving these constraints, PBHs were treated as point Schwarzschild masses, while the more careful analysis in an expanding universe we present here, leads to a time-dependent mass. This implies a stricter set of conditions for a black hole binary to form and means that black holes coalesce much more quickly than was previously calculated, namely well before the LIGO/Virgo's observed mergers. The observed binaries are those coalescing within galactic halos, with a merger rate consistent with data. This reopens the possibility for dark matter in the form of LIGO-mass PBHs.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2021)·74 citations
18. 18*

    Helical magnetic fields from Riemann coupling

    Ashu Kushwaha🇮🇳 · S. Shankaranarayanan (IIT Bombay)🇮🇳

    We study the inflationary generation of helical magnetic fields from the Riemann coupling with the electromagnetic field. Most models in the literature introduce non-minimal coupling to the electromagnetic fields with a scalar field, hence, breaking the conformal invariance. In this work, we show that non-minimal coupling to the Riemann tensor generates sufficient primordial helical magnetic fields at all observable scales. We explicitly show that one of the helical states decay while the other helical mode increases, leading to a net non-zero helicity. Our model has three key features:~(i) the helical power-spectrum has a slight red-tilt for slow-roll inflation consistent with bounds from observations and free from backreaction problem, (ii) the energy density of the helical fields generated is at least one order of magnitude larger than the scalar-field coupled models, and (iii) unlike the scalar field coupled models, the generated helical fields are insensitive to the reheating dynamics. We show that our model generates the magnetic field of strength 0.01 PicoGauss over Mpc scale.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·25 citations
19. 19*

    Matrix Element Regression with Deep Neural Networks -- breaking the CPU barrier

    Florian Bury🇧🇪 · Christophe Delaere🇧🇪

    The Matrix Element Method (MEM) is a powerful method to extract information from measured events at collider experiments. Compared to multivariate techniques built on large sets of experimental data, the MEM does not rely on an examples-based learning phase but directly exploits our knowledge of the physics processes. This comes at a price, both in term of complexity and computing time since the required multi-dimensional integral of a rapidly varying function needs to be evaluated for every event and physics process considered. This can be mitigated by optimizing the integration, as is done in the MoMEMta package, but the computing time remains a concern, and often makes the use of the MEM in full-scale analysis unpractical or impossible. We investigate in this paper the use of a Deep Neural Network (DNN) built by regression of the MEM integral as an ansatz for analysis, especially in the search for new physics.

    ↳ hep-exhep-phJHEP(2021)·16 citations
20. 20*

    Dissipative Spin Dynamics in Relativistic Matter

    Samapan Bhadury🇮🇳 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Avdhesh Kumar🇮🇳 · Radoslaw Ryblewski🇵🇱

    Using classical description of spin degrees of freedom, we extend recent formulation of the perfect-fluid hydrodynamics for spin-polarized fluids to the case including dissipation. Our work is based on the analysis of classical kinetic equations for massive particles with spin-1/2, with the collision terms treated in the relaxation time approximation. The kinetic-theory framework determines the structure of viscous and diffusive terms and allows to explicitly calculate a complete set of new kinetic coefficients that characterize dissipative spin dynamics.

    ↳ nucl-thhep-phhep-thPRD(2021)·126 citations
21. 21*

    Particle mixing and the emergence of classicality: A spontaneous-collapse-model view

    Kyrylo Simonov🇦🇹

    Spontaneous collapse models aim to resolve the measurement problem in quantum mechanics by considering wave-function collapse as a physical process. We analyze how these models affect a decaying flavor-oscillating system whose evolution is governed by a phenomenological non-Hermitian Hamiltonian. In turn, we apply two popular collapse models, the Quantum Mechanics with Universal Position Localization and the Continuous Spontaneous Localization models, to a neutral meson system. By using the equivalence between the approaches to the time evolution of decaying systems with a non-Hermitian Hamiltonian and a dissipator of the Lindblad form in an enlarged Hilbert space, we show that spontaneous collapse can induce the decay dynamics in both quantum state and master equations. Moreover, we show that the decay property of a flavor-oscillating system is intimately connected to the time (a)symmetry of the noise field underlying the collapse mechanism. This (a)symmetry, in turn, is related to the definition of the stochastic integral and can provide a physical intuition behind the Itō-Stratonovich dilemma in stochastic calculus.

    ↳ quant-phhep-phPRA(2020)·4 citations
22. 22*

    Nuclear matrix elements from lattice QCD for electroweak and beyond-Standard-Model processes

    Zohreh Davoudi🇺🇸 · William Detmold🇺🇸 · Kostas Orginos🇺🇸 · Assumpta Parreño🇪🇸 · Martin J. Savage🇺🇸 · Phiala Shanahan🇺🇸 · Michael L. Wagman🇺🇸

    Over the last decade, numerical solutions of Quantum Chromodynamics (QCD) using the technique of lattice QCD have developed to a point where they are beginning to connect fundamental aspects of nuclear physics to the underlying degrees of freedom of the Standard Model. In this review, the progress of lattice QCD studies of nuclear matrix elements of electroweak currents and beyond-Standard-Model operators is summarized, and connections with effective field theories and nuclear models are outlined. Lattice QCD calculations of nuclear matrix elements can provide guidance for low-energy nuclear reactions in astrophysics, dark matter direct detection experiments, and experimental searches for violations of the symmetries of the Standard Model, including searches for additional CP violation in the hadronic and leptonic sectors, baryon-number violation, and lepton-number or flavor violation. Similarly, important inputs to neutrino experiments seeking to determine the neutrino-mass hierarchy and oscillation parameters, as well as other electroweak and beyond-Standard-Model processes can be determined. The phenomenological implications of existing studies of electroweak and beyond-Standard-Model matrix elements in light nuclear systems are discussed, and future prospects for the field toward precision studies of these matrix elements are outlined.

    ↳ hep-lathep-phnucl-thPhys.Rept.(2021)·97 citations
23. 23*

    Equilibrium axisymmetric halo model for the Milky Way and its implications for direct and indirect DM searches

    Mihael Petac🇮🇹

    We for the first time provide self-consistent axisymmetric phase-space distribution models for the Milky Way's dark matter (DM) halo which are carefully matched against the latest kinematic measurements through Bayesian analysis. By using broad priors on the individual galactic components, we derive conservative estimates for the astrophysical factors entering the interpretation of direct and indirect DM searches. While the resulting DM density profiles are in good agreement with previous studies, implying ${\rho }_{\odot }\approx 10^{-2}{M}_{\odot }/{\mathrm{pc}}^3$, the presence of baryonic disc leads to significant differences in the local DM velocity distribution in comparison with the standard halo model. For direct detection, this implies roughly 30% stronger cross-section limits at DM masses near detectors maximum sensitivity and up to an order of magnitude weaker limits at the lower end of the mass range. Furthermore, by performing Monte-Carlo simulations for the upcoming DARWIN and DarkSide-20k experiments, we demonstrate that upon successful detection of heavy DM with coupling just below the current limits, the carefully constructed axisymmetric models can eliminate bias and reduce uncertainties by more then 50% in the reconstructed DM coupling and mass, but also help in a more reliable determination of the scattering operator. Furthermore, the velocity anisotropies induced by the baryonic disc can lead to significantly larger annual modulation amplitude and sizable differences in the directional distribution of the expected DM-induced events. For indirect searches, we provide the differential $J$-factors and compute several moments of the relative velocity distribution that are needed for predicting the rate of velocity-dependent annihilations. However, we find that accurate predictions are still hindered by large uncertainties regarding the DM distribution near the galactic center.

    ↳ astro-ph.GAhep-exhep-phPRD(2020)·10 citations
24. 24*

    Multi-messenger Probes of Inflationary Fluctuations and Primordial Black Holes

    Caner Unal🇨🇿 · Ely D. Kovetz🇮🇱 · Subodh P. Patil🇩🇰

    Next generation cosmic microwave background spectral distortion and pulsar timing array experiments have the potential to probe primordial fluctuations at small scales with remarkable sensitivity. We demonstrate the potential of these probes to either detect signatures of primordial black holes (PBHs) sourced from primordial overdensities within the standard thermal history of the universe over a 13-decade mass range $\mathcal{O}(0.1-10^{12})M_{\odot }$, or constrain their existence to a negligible abundance. Our conclusions are based only on global cosmological signals, and are robust under changes in i) the statistical properties of the primordial density fluctuations (whether Gaussian or non-Gaussian), ii) the merger and accretion history of the PBHs and assumptions about associated astrophysical processes, and iii) clustering statistics. Any positive detection of enhanced primordial fluctuations at small scales would have far-reaching implications from the content of dark matter to origin of BHs in the centers of galaxies, and to the field content of the inflation. On the other hand, their non-detection would also have important corollaries. For example, non-detection up to forecast sensitivities would tell us that PBHs larger than a fraction of a solar mass can constitute no more than a negligible fraction of dark matter. Moreover, non-detection will also rule out the scenario that PBHs generated by primordial overdensities could be the progenitors of super-massive black holes (SMBHs), of topical interest as there are only a few widely accepted proposals for the formation of SMBHs, an even more pressing question after the detection of active galactic nuclei over a billion solar masses at redshifts $z\ge 7$. Finally, non-detection sets the strongest bounds on the amplitude of small scale inflationary fluctuations for over 6 decades.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1PRD(2021)·71 citations
25. 25*

    New Limits on Axionic Dark Matter from the Magnetar PSR J1745-2900

    Jeremy Darling🇺🇸

    Axions are a promising dark matter candidate that were motivated to solve the strong CP problem and that may also address the cosmological matter-antimatter asymmetry. Axion-photon conversion is possible in the presence of the strong magnetic fields, and the photon so produced will have energy equal to the axion mass. Here we report new limits on axionic dark matter obtained from radio spectra of the Galactic Center magnetar PSR J1745-2900. The magnetar has a magnetic field of $1.6\times 10^{14}$ G that interacts with a dark matter density $2\times 10^5$ to $2\times 10^9$ times greater than the local dark matter encountered by terrestrial haloscopes, depending on the Galactic dark matter profile. No significant spectral features are detected across 62% of the axion mass range 4.1-165.6 $\mu$eV (1-40 GHz). The interpretation of flux limits into limits on the two-photon coupling strength $g_{a\gamma \gamma }$ depends on the magnetospheric conversion model and on the dark matter density at the Galactic Center. For a standard dark matter profile, we exclude axion models with $g_{a\gamma \gamma }>$ 6-34 $\times 10^{-12}$ GeV${}^{-1}$ with 95% confidence over the mass ranges 4.2-8.4, 8.9-10.0, 12.3-16.4, 18.6-26.9, 33.0-62.1, 70.1-74.3, 78.1-80.7, 105.5-109.6, 111.6-115.2, 126.0-159.3, and 162.5-165.6 $\mu$eV. For the maximal dark matter cusp allowed by stellar orbits near Sgr A*, these limits reduce to $g_{a\gamma \gamma }>$ 6-34 $\times 10^{-14}$ GeV${}^{-1}$, which exclude some theoretical models for masses $>33$ $\mu$eV. Limits may be improved by modeling stimulated axion conversion, by ray-tracing conversion pathways in the magnetar magnetosphere, and by obtaining deeper broad-band observations of the magnetar.

    ↳ astro-ph.COhep-phApJL(2020)·67 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.