Thu·Apr 2, 2020Thursday·April 2, 2020

1. 01*

   Comparison of optical potential for nucleons and $\Delta$ resonances

   Arie Bodek🇺🇸 · Tejin Cai🇺🇸

   Precise modeling of neutrino interactions on nuclear targets is essential for neutrino oscillations experiments. The modeling of the energy of final state particles in quasielastic (QE) scattering and resonance production on bound nucleons requires knowledge of both the removal energy of the initial state bound nucleon as well as the average Coulomb and nuclear optical potentials for final state leptons and hadrons. We extract the average values of the real part of the nuclear optical potential for final state nucleons ($U_{opt}^{QE}$) as a function of the nucleon kinetic energy from inclusive electron scattering data on nuclear targets (${}_6^{12}\mathbf{C}$+${}_8^{16}\mathbf{O}$, ${}_{20}^{40}\mathbf{Ca}$+${}_{18}^{40}\mathbf{Ar}$, ${}_3^6\mathbf{Li}$, ${}_{18}^{27}\mathbf{Al}$, ${}_{26}^{56}\mathbf{Fe}$, ${}_{82}^{208}\mathbf{Pb}$) in the QE region and compare to calculations. We also extract values of the average of the real part of the nuclear optical potential for a $\Delta (1232)$ resonance in the final state ($U_{opt}^{\Delta }$) within the impulse approximation. We find that $U_{opt}^{\Delta }$ is more negative than $U_{opt}^{QE}$ with $U_{opt}^{\Delta }\approx$1.5~$U_{opt}^{QE}$ for ${}_6^{12}\mathbf{C}$.

   hep-phnucl-thEPJC(2020)·18 citations
2. 02*

   Gauge hierarchy problem and scalegenesis

   Masatoshi Yamada🇩🇪

   We review the gauge hierarchy problem in the standard model. We discuss the meaning of the quadratic divergence in terms of the Wilsonian renormalization group. Classical scale symmetry, which prohibits dimensionful parameters in the bare action, could play a key role for the understanding of the origin of the electroweak scale. We discuss the scale-generation mechanism, i.e. scalegenesis in scale invariant theories. In this paper, we introduce a scale invariant extension of the SM based on a strongly interacting scalar-gauge theory. It is discussed that asymptotically safe quantum gravity provides a hint about solutions to the gauge hierarchy problem.

   hep-phhep-thPoS(2020)·11 citations
3. 03*

   General neutrino mass spectrum and mixing properties in seesaw mechanisms

   Wojciech Flieger🇵🇱 · Janusz Gluza🇵🇱

   Neutrinos stand out among elementary particles through their unusually small masses. Various seesaw mechanisms attempt to explain this fact. In this work applying insights from matrix theory we are in a position to treat variants of seesaw mechanisms in a general manner. Specifically, using Weyl's inequalities we discuss and rigorously prove under which conditions the seesaw framework leads to a mass spectrum with exactly three light neutrinos. We find an estimate on the mass of heavy neutrinos to be the mass obtained by neglecting light neutrinos shifted at most by the maximal strength of the coupling to the light neutrino sector. We provide analytical conditions allowing to prescribe that precisely two out of five neutrinos are heavy. For higher-dimensional cases the inverse eigenvalue methods are used. In particular, for the CP invariant scenarios we show that if the neutrino sector has a valid mass matrix after neglecting the light ones, i.e. the respective mass submatrix is positive definite, then large masses are provided by matrices with large elements accumulated on the diagonal. Finally, the Davis-Kahan theorem is used to show how masses affect the rotation of light neutrino eigenvectors from the standard Euclidean basis. This general observation concerning neutrino mixing together with results on the mass spectrum properties opens directions for further neutrino physics studies using matrix analysis.

   hep-phCPC(2021)·10 citations
4. 04*

   Spectrum of scalar and pseudoscalar glueballs from functional methods

   Markus Q. Huber🇩🇪 · Christian S. Fischer🇩🇪 · Hèlios Sanchis-Alepuz🇦🇹

   We provide results for the spectrum of scalar and pseudoscalar glueballs in pure Yang-Mills theory using a parameter-free fully self-contained truncation of Dyson-Schwinger and Bethe-Salpeter equations. The only input, the scale, is fixed by comparison with lattice calculations. We obtain ground state masses of $1.9\text{GeV}$ and $2.6\text{GeV}$ for the scalar and pseudoscalar glueballs, respectively, and $2.6\text{GeV}$ and $3.9\text{GeV}$ for the corresponding first excited states. This is in very good quantitative agreement with available lattice results. Furthermore, we predict masses for the second excited states at $3.7\text{GeV}$ and $4.3\text{GeV}$. The quality of the results hinges crucially on the self-consistency of the employed input. The masses are independent of a specific choice for the infrared behavior of the ghost propagator providing further evidence that this only reflects a nonperturbative gauge completion.

   hep-phhep-lathep-thEPJC(2020)·79 citations
5. 05*

   Multigap diffraction cross sections. Problems in eikonal methods for the pomeron unitarization

   E. Martynov🇺🇦 · G. Tersimonov🇺🇦

   Large rapidity gap diffraction processes are considered in multi-channel eikonal models. It is shown that shadow corrections to over-fast rising contribution of the input supercritical pomeron (with $\alpha (0)>1$), originating from the pomeron rescatterings or, equivalently, accounting survival probability factor, do not solve the Finkelstein-Kajantie problem. Therefore, in our opinion, another methods of unitarization of supercritical pomeron should be developed.

   hep-phPRD(2020)·4 citations
6. 06*

   Recursive fragmentation of a polarized quark

   Albi Kerbizi🇮🇹

   The thesis is devoted to the study of the fragmentation process of polarized quarks, and in particular of the Collins effect used for the extraction of the quark transversity distribution. The aim is to include the spin degree of freedom in the hadronization part of Monte Carlo event generators by using the string+${}^3{P}_0$ model. The model is reviewed here and the relevant functions have been written in a form suitable for a Monte Carlo implementation. Two main variants of the model for pseudoscalar meson production are formulated and both of them have been implemented in stand alone Monte Carlo programs. After tuning one single parameter, the simulation results are compared with the measured Collins and dihadron transverse spin asymmetries showing a satisfactory qualitative agreement. Given this encouraging outcome, one of them has been interfaced with the hadronization part of the PYTHIA event generator. The quark transversity distribution has been implemented in the generator allowing to simulate for the first time the polarized SIDIS process. The comparison of the simulated transverse spin asymmetries with the experimental data is found to be very promising. As final development, vector meson production and decays have been included in a consistent way with the rules of quantum mechanics. The effect of vector meson production on transverse spin asymmetries has been studied in detail with a stand alone Monte Carlo program showing that the new model is a promising and powerful model for the description of the polarized quark fragmentation process.

   hep-ph3 citations
7. 07*

   Identifying the ${\Xi }_c^0$ baryons observed by LHCb as $P$-wave ${\Xi }_c^{\prime }$ baryons

   Hui-Min Yang🇨🇳 · Hua-Xing Chen🇨🇳 · Qiang Mao🇨🇳

   We systematically study mass spectra and decay properties of $P$-wave ${\Xi }_c^{\prime }$ baryons of the $SU(3)$ flavor $6_F$, using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the three excited ${\Xi }_c^0$ baryons recently observed by LHCb can be well explained as $P$-wave ${\Xi }_c^{\prime }$ baryons: the ${\Xi }_c(2923{)}^0$ and ${\Xi }_c(2939{)}^0$ are partner states of $J^P=1/2^{-}$ and $3/2^{-}$ respectively, both of which contain one $\lambda$-mode orbital excitation; the ${\Xi }_c(2965{)}^0$ has $J^P=3/2^{-}$, and also contains one $\lambda$-mode orbital excitation. We propose to search for another $P$-wave ${\Xi }_c^{\prime }$ state of $J^P=5/2^{-}$ in the ${\Lambda }_{c}K/{\Xi }_c\pi$ mass spectral in future experiments. Its mass is about $56_{-35}^{+30}$ MeV larger than the ${\Xi }_c(2965{)}^0$, and its width is about $18.1_{-8.3}^{+19.7}$ MeV.

   hep-phhep-exhep-latPRD(2020)·28 citations
8. 08*

   Approximate four-loop QCD corrections to the Higgs-boson production cross section

   G. Das (Siegen U.)🇩🇪 · S. Moch (Hamburg U., Inst. Theor. Phys. II)🇩🇪 · A. Vogt (Liverpool U., Dept. Math.)🇬🇧

   We study the soft and collinear (SV) contributions to inclusive Higgs-boson production in gluon-gluon fusion at four loops. Using recent progress for the quark and gluon form factors and Mellin moments of splitting functions, we are able to complete the soft-gluon enhanced contributions exactly in the limit of a large number of colours, and to a sufficiently accurate numerical accuracy for QCD. The four-loop SV contributions increase the QCD cross section at 14 TeV by 2.7% and 0.2% for the standard choices mu_R=m_H and mu_R=m_H/2 of the renormalization scale, and reduce the scale uncertainty to below +-3%. As by-products, we derive the complete delta(1-x) term for the gluon-gluon splitting function at four loops and its purely Abelian contributions at five loops, and provide a numerical result for the single pole of the four-loop gluon form factor in dimensional regularization. Finally we present the closely related fourth-order coefficients D_4 for the soft-gluon exponentiation of Higgs-boson and Drell-Yan lepton-pair production.

   hep-phPLB(2020)·63 citations
9. 09*

   TeV-scale Majorogenesis

   Yoshihiko Abe🇯🇵 · Yu Hamada🇯🇵 · Takahiro Ohata🇯🇵 · Kenta Suzuki🇯🇵 · Koichi Yoshioka🇯🇵

   The Majoron, the Nambu-Goldstone boson of lepton number symmetry, is an interesting candidate for dark matter as it deeply connects the dark matter and neutrino physics. In this paper, we consider the Majoron dark matter as pseudo Nambu-Goldstone boson with TeV-scale mass. The heavy Majoron generally has the large decay constant and tiny Yukawa couplings to light right-handed neutrinos which are required by cosmological and astrophysical observations. That makes it difficult to realize the desired amount of the relic abundance of Majoron dark matter. We consider three improved scenarios for the generation of Majoron, dubbed as Majorogenesis, in the early universe and find in all cases the parameter space compatible with the relic abundance and cosmic-ray constraints.

   hep-phJHEP(2020)·26 citations
10. 10*

    Exclusive photoproduction of excited quarkonia in ultraperipheral collisions

    Cheryl Henkels🇧🇷 · Emmanuel G. de Oliveira🇧🇷 · Roman Pasechnik🇧🇷 · Haimon Trebien🇧🇷

    In this paper, we discuss the exclusive photoproduction of ground and excited states of $\psi (1S,2S)$ and ${\rm Y}(1S,2S)$ in ultraperipheral collisions (UPCs). Using the potential model in order to obtain the vector meson wave function, we find a good agreement of our calculations with data from the LHC and HERA colliders for $J/\psi (1S,2S)$ and ${\rm Y}(1S)$ in $\gamma p$ collisions. We extend the calculations to the nuclear target case applying them to $AA$ UPCs with the use of the shadowing and finite coherence length effects fitted to the data. Our results are compared to the recent LHC data, in both incoherent ($J/\Psi (1S)$ at 2.76 TeV) and coherent ($J/\Psi (1S)$ at 2.76 and 5.02 TeV) processes. We also show the corresponding predictions for the excited states, in the hope that future measurements could provide more detailed information about the vector meson wave functions and nuclear effects.

    hep-phPRD(2020)·16 citations
11. 11*

    Recurrent form of the renormalization group relations for the higher-order hadronic vacuum polarization function perturbative expansion coefficients

    A.V.Nesterenko🇷🇺

    The renormalization group relations for the higher-order hadronic vacuum polarization function perturbative expansion coefficients are studied. The folded recurrent and unfolded explicit forms of such relations are obtained. The explicit expression for the coefficients, which incorporate the contributions of the ${\pi }^2$-terms in the perturbative expansion of the R-ratio of electron-positron annihilation into hadrons, is derived at an arbitrary loop level. The obtained results can be employed as an independent crosscheck of the higher-order perturbative calculations of the hadronic vacuum polarization function and in the studies of the renormalization scale setting in the relevant physical observables.

    hep-phhep-lathep-thJ.Phys.G(2020)·7 citations
12. 12*

    Axion Kinetic Misalignment and Parametric Resonance from Inflation

    Raymond T. Co🇺🇸 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸 · Keith A. Olive🇺🇸 · Sarunas Verner🇺🇸

    Axion cold dark matter from standard misalignment typically requires a decay constant $f_a\gtrsim 10^{11}$ GeV. Kinetic misalignment and parametric resonance easily allow lower values of $f_a$ when the radial Peccei-Quinn (PQ) symmetry breaking field takes large initial values. Here, we consider the effects of inflation on kinetic misalignment and parametric resonance. We assume that the initial PQ field value is determined by quantum fluctuations, and is set by the Hubble parameter during inflation, $H_I$, and the PQ field mass. PQ field oscillations begin before or after the completion of reheating after inflation at a temperature $T_R$. We determine the range of $f_a$ and the inflationary parameters $(H_I,T_R)$ consistent with axion dark matter for a quartic potential for the PQ field. We find that $4\times 10^8$ GeV $<f_a<10^{11}$ GeV can consistently produce axion dark matter. A significant portion of the allowed parameter space predicts rare kaon decays, $K_L\to ({\pi }^0+\mathrm{missing}\mathrm{energy})$, and/or suppression of structure formation on small scales.

    hep-phastro-ph.COJCAP(2020)·110 citations
13. 13*

    Jet Substructure from Dark Sector Showers

    Timothy Cohen🇺🇸 · Joel Doss🇺🇸 · Marat Freytsis🇺🇸

    We examine the robustness of collider phenomenology predictions for a dark sector scenario with QCD-like properties. Pair production of dark quarks at the LHC can result in a wide variety of signatures, depending on the details of the new physics model. A particularly challenging signal results when prompt production induces a parton shower that yields a high multiplicity of collimated dark hadrons with subsequent decays to Standard Model hadrons. The final states contain jets whose substructure encodes their non-QCD origin. This is a relatively subtle signature of strongly coupled beyond the Standard Model dynamics, and thus it is crucial that analyses incorporate systematic errors to account for the approximations that are being made when modeling the signal. We estimate theoretical uncertainties for a canonical substructure observable designed to be sensitive to the gauge structure of the underlying object, the two-point energy correlator $e_2^{(\beta )}$, by computing envelopes between resummed analytic distributions and numerical results from Pythia. We explore the separability against the QCD background as the confinement scale, number of colors, number of flavors, and dark quark masses are varied. Additionally, we investigate the uncertainties inherent to modeling dark sector hadronization. Simple estimates are provided that quantify one's ability to distinguish these dark sector jets from the overwhelming QCD background. Such a search would benefit from theory advances to improve the predictions, and the increase in statistics using the data to be collected at the high luminosity LHC.

    hep-phJHEP(2020)·62 citations
14. 14*

    Baryogenesis and Dark Matter from Freeze-In

    Brian Shuve🇺🇸 · David Tucker-Smith🇺🇸

    We propose a simple model in which the baryon asymmetry and dark matter are created via the decays and inverse decays of QCD-triplet scalars, at least one of which must be in the TeV mass range. Singlet fermions produced in these decays constitute the dark matter. The singlets never reach equilibrium, and their coherent production, propagation, and annihilation generates a baryon asymmetry. We find that that the out-of-equilibrium condition and the dark matter density constraint typically require the lightest scalar to be long-lived, giving good prospects for detection or exclusion in current and upcoming colliders. In generalizing the leptogenesis mechanism of Akhmedov, Rubakov and Smirnov, our model expands the phenomenological possibilities for low-scale baryogenesis.

    hep-phastro-ph.COPRD(2020)·14 citations
15. 15*

    Phenomenology and Cosmology of No-Scale Attractor Models of Inflation

    John Ellis🇬🇧 · Dimitri V. Nanopoulos🇺🇸 · Keith A. Olive🇺🇸 · Sarunas Verner🇺🇸

    We have recently proposed attractor models for modulus fixing, inflation, supersymmetry breaking and dark energy based on no-scale supergravity. In this paper we develop phenomenological and cosmological aspects of these no-scale attractor models that underpin their physical applications. We consider models in which inflation is driven by a modulus field ($T$-type) with supersymmetry broken by a Polonyi field, or a matter field ($\varphi$-type) with supersymmetry broken by the modulus field. We derive the possible patterns of soft supersymmetry-breaking terms, which depend in $T$-type models whether the Polonyi and/or matter fields are twisted or not, and in $\varphi$-type models on whether the inflaton and/or other matter fields are twisted or not. In $\varphi$-type models, we are able to directly relate the scale of supersymmetry breaking to the inflaton mass. We also discuss cosmological constraints from entropy considerations and the density of dark matter on the mechanism for stabilizing the modulus field via higher-order terms in the no-scale Kähler potential.

    hep-phastro-ph.COhep-thJCAP(2020)·30 citations
16. 16*

    Quark model relations for b-baryon decay

    Jerrold Franklin🇺🇸

    Properties of b-baryon decay matrix elements (amplitudes) have been derived in a nonsymmetric quark model without any use of SU(6), SU(3), or SU(2) (isotopic spin) groups. Equalities between pairs of amplitudes are derived, and $\Lambda -\Sigma$ mixing is used to calculate the branching ratio for the transition ${\Lambda }_b\to {\Sigma }^0$.

    hep-phhep-exnucl-thJ.Phys.G(2020)·3 citations
17. 17*

    The web of swampland conjectures and the TCC bound

    David Andriot🇦🇹 · Niccolò Cribiori🇦🇹 · David Erkinger🇦🇹

    We consider the swampland distance and de Sitter conjectures, of respective order one parameters $\lambda$ and $c$. Inspired by the recent Trans-Planckian Censorship conjecture (TCC), we propose a generalization of the distance conjecture, which bounds $\lambda$ to be a half of the TCC bound for $c$, i.e. $\lambda \ge \frac{1}{2}\sqrt{\frac{2}{3}}$ in 4d. In addition, we propose a correspondence between the two conjectures, relating the tower mass $m$ on the one side to the scalar potential $V$ on the other side schematically as $m\sim |V{|}^{\frac{1}{2}}$, in the large distance limit. These proposals suggest a generalization of the scalar weak gravity conjecture, and are supported by a variety of examples. The lower bound on $\lambda$ is verified explicitly in many cases in the literature. The TCC bound on $c$ is checked as well on ten different no-go theorems, which are worked-out in detail, and $V$ is analysed in the asymptotic limit. In particular, new results on 4d scalar potentials from type II compactifications are obtained.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·143 citations
18. 18*

    Scale symmetry, the Higgs and the Cosmos

    Javier Rubio🇩🇪

    I review the Higgs-Dilaton model: a scale-invariant extension of the Standard Model and gravity able to support inflation and dark energy with just an additional degree of freedom on top of the Standard Model content. Potential extensions of the simplest realization on the basis of transverse diffeomorphisms are also discussed.

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

    Implementation of muon pair production in PHITS and verification by comparing with the muon shielding experiment at SLAC

    Yasuhito Sakaki🇯🇵 · Yoshihito Namito🇯🇵 · Toshiya Sanami🇯🇵 · Hiroshi Iwase🇯🇵 · Hideo Hirayama🇯🇵

    We implemented a model of muon pair production through a real photon in PHITS and compared our calculations with data of the muon shielding experiment conducted at SLAC to verify the validity of the implemented model. Our predictions of the muon fluence induced by electrons are in good agreement with the experimental data. To understand the known differences between the calculations of the muon fluence, which have been determined using other Monte-Carlo codes, we quantitatively evaluate the fluctuations in the Monte-Carlo results due to systematic errors in multiple Coulomb scattering, differences in the approximation methods and energy loss models, and whether incoherent production is considered.

    ↳ physics.acc-phhep-phNucl.Instrum.Meth.A(2020)·6 citations
20. 20*

    Two-loop renormalization of the matter superfields and finiteness of $\mathcal{N}=1$ supersymmetric gauge theories regularized by higher derivatives

    Alexander Kazantsev🇷🇺 · Konstantin Stepanyantz🇷🇺

    The two-loop anomalous dimension of the chiral matter superfields is calculated for a general $\mathcal{N}=1$ supersymmetric gauge theory regularized by higher covariant derivatives. We obtain both the anomalous dimension defined in terms of the bare couplings, and the one defined in terms of the renormalized couplings for an arbitrary renormalization prescription. For the one-loop finite theories we find a simple relation between the higher derivative regulators under which the anomalous dimension defined in terms of the bare couplings vanishes in the considered approximation. In this case the one-loop finite theory is also two-loop finite in the HD+MSL scheme. Using the assumption that with the higher covariant derivative regularization the NSVZ equation is satisfied for RGFs defined in terms of the bare couplings, we construct the expression for the three-loop $\beta$-function. Again, the result is written both for the $\beta$-function defined in terms of the bare couplings and for the one defined in terms of the renormalized couplings for an arbitrary renormalization prescription.

    ↳ hep-thhep-phJHEP(2020)·31 citations
21. 21*

    Model-independent test for CPT violation using long-baseline and atmospheric neutrino experiments

    Daljeet Kaur🇮🇳

    Charge-Parity-Time (CPT) symmetry governs that the oscillation parameters for neutrinos and anti-neutrinos are to be identical. Different mass and mixing parameters for these particles may give us a possible hint for CPT violation in the neutrino sector. Using this approach, we discuss the ability of long-baseline and atmospheric neutrino experiments to determine the difference between mass squared splittings ($\Delta m_{32}^2-\Delta {\bar{m}}_{32}^2$) and atmospheric mixing angles (${\sin }^2{\theta }_{23}-{\sin }^2{\bar{\theta }}_{23}$) of neutrinos and anti-neutrinos. We show the joint sensitivity of the T2K, NOvA and INO experiments to such CPT violating observables in different possible combinations of octant for neutrinos and anti-neutrinos.

    ↳ hep-exhep-phPRD(2020)·6 citations
22. 22*

    Ghost Problems from Pauli-Villars to Fourth-Order Quantum Gravity and their Resolution

    Philip D. Mannheim🇺🇸

    We review the history of the ghost problem in quantum field theory from the Pauli-Villars regulator theory to currently popular fourth-order derivative quantum gravity theories. While these theories all appear to have unitarity-violating ghost states with negative norm, we show that in fact these ghost states only appear because the theories are being formulated in the wrong Hilbert space. In these theories the Hamiltonians are not Hermitian but instead possess an antilinear symmetry. Consequently, one cannot use inner products that are built out of states and their Hermitian conjugates. Rather, one must use inner products built out of states and their conjugates with respect to the antilinear symmetry, and these latter inner products are positive. In this way one can build quantum theories of gravity in four spacetime dimensions that are unitary.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.D(2020)·30 citations
23. 23*

    Chirality and Magnetic Field

    Defu Hou🇨🇳 · Anping Huang🇺🇸 · Jinfeng Liao🇺🇸 · Shuzhe Shi🇨🇦 · Hui Zhang🇨🇳

    We present a brief overview on recent developments of theory and phenomenology for novel many-body phenomena related to the chirality and magnetic field, with an emphasis on their experimental implications and possible detection in relativistic nuclear collisions.

    ↳ nucl-thhep-phnucl-exNPA(2021)·4 citations
24. 24*

    Hot Gravitons and Gravitational Waves From Kerr Black Holes in the Early Universe

    Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸 · John March-Russell🇬🇧 · Samuel D. McDermott🇺🇸 · Rudin Petrossian-Byrne🇬🇧

    Any abundance of black holes that was present in the early universe will evolve as matter, making up an increasingly large fraction of the total energy density as space expands. This motivates us to consider scenarios in which the early universe included an era that was dominated by low-mass ($M<5\times 10^8$ g) black holes which evaporate prior to primordial nucleosynthesis. In significant regions of parameter space, these black holes will become gravitationally bound within binary systems, and undergo mergers before evaporating. Such mergers result in three potentially observable signatures. First, any black holes that have undergone one or more mergers will possess substantial angular momentum, causing their Hawking evaporation to produce significant quantities of high-energy gravitons. These products of Hawking evaporation are predicted to constitute a background of hot ($\sim$eV-keV) gravitons today, with an energy density corresponding to $\Delta N_{\mathrm{eff}}\sim 0.01-0.03$. Second, these mergers will produce a stochastic background of high-frequency gravitational waves. And third, the energy density of these gravitational waves can be as large as $\Delta N_{\mathrm{eff}}\sim 0.3$, depending on the length of time between the mergers and evaporation. These signals are each potentially within the reach of future measurements.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph+1121 citations
25. 25*

    Graviton non-Gaussianities and Parity Violation in the EFT of Inflation

    Lorenzo Bordin🇬🇧 · Giovanni Cabass🇩🇪

    We study graviton non-Gaussianities in the EFT of Inflation. At leading (second) order in derivatives, the graviton bispectrum is fixed by Einstein gravity. There are only two contributions at third order. One of them breaks parity. They come from operators that directly involve the foliation: we then expect sizable non-Gaussianities in three-point functions involving both gravitons and scalars. However, we show that at leading order in slow roll the parity-odd operator does not modify these mixed correlators. We then identify the operators that can affect the graviton bispectrum at fourth order in derivatives. There are two operators that preserve parity. We show that one gives a scalar-tensor-tensor three-point function larger than the one computed in Maldacena, 2003 if $M_{\mathrm{P}}^2{A}_{\mathrm{s}}/{\Lambda }^2\gg 1$ (where $\Lambda$ is the scale suppressing this operator and $A_{\mathrm{s}}$ the amplitude of the scalar power spectrum). There are only two parity-odd operators at this order in derivatives.

    ↳ astro-ph.COhep-phJCAP(2020)·51 citations
26. 26*

    INTEGRAL constraints on primordial black holes and particle dark matter

    Ranjan Laha🇨🇭 · Julian B. Muñoz🇺🇸 · Tracy R. Slatyer🇺🇸

    The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has yielded unprecedented measurements of the soft gamma-ray spectrum of our Galaxy. Here we use those measurements to set constraints on dark matter (DM) that decays or annihilates into photons with energies $E\approx 0.02-2$ MeV. First, we revisit the constraints on particle DM that decays or annihilates to photon pairs. In particular, for decaying DM, we find that previous limits were overstated by roughly an order of magnitude. Our new, conservative analysis finds that the DM lifetime must satisfy $\tau \gtrsim 5\times 10^{26}\mathrm{s}\times (m_{\chi }/\mathrm{MeV}{)}^{-1}$ for DM masses $m_{\chi }=0.054-3.6$ MeV. For MeV-scale DM that annihilates into photons INTEGRAL sets the strongest constraints to date. Second, we target ultralight primordial black holes (PBHs) through their Hawking radiation. This makes them appear as decaying DM with a photon spectrum peaking at $E\approx 5.77/(8\pi G{M}_{\mathrm{PBH}})$, for a PBH of mass $M_{\mathrm{PBH}}$. We use the INTEGRAL data to demonstrate that, at 95\% C.L., PBHs with masses less than $1.2\times 10^{17}$ g cannot comprise all of the DM, setting the tightest bound to date on ultralight PBHs.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2020)·302 citations
27. 27*

    Constraints on Standard Model Constructions in F-theory

    Mirjam Cvetic🇺🇸 · James Halverson🇺🇸 · Ling Lin🇺🇸 · Cody Long🇺🇸

    We argue that the following three statements cannot all be true: (i) our vacuum is a type IIB / F-theory vacuum at moderate-to-large $h^{1,1}$, (ii) the ${\alpha }^{\prime }$-expansion is controlled via the supergravity approximation, à la the KKLT and LVS scenarios, and (iii) there are no additional gauged sectors from seven-branes. Since nearly all known globally consistent F-theory models with the exact chiral spectrum of the Standard Model and gauge coupling unification occur at moderate $h^{1,1}$, this finding calls for new moduli stabilization scenarios or/and a rich seven-brane dark sector.

    ↳ hep-thhep-phPRD(2020)·9 citations
28. 28*

    X-ray annual modulation observed by XMM-Newton and Axion Quark Nugget Dark Matter

    Shuailiang Ge🇨🇦 · Hikari Rachmat🇨🇦 · Md Shahriar Rahim Siddiqui🇨🇦 · Ludovic Van Waerbeke🇨🇦 · Ariel Zhitnitsky🇨🇦

    The XMM-Newton observatory shows evidence, with a 11$\sigma$ confidence level, for seasonal variation of the X-ray background in the near-Earth environment in the 2-6 keV energy range (Fraser et al. 2014). The authors argue that the observed seasonal variation suggests a possible link with dark matter. We propose an explanation which involves the Axion Quark Nugget (AQN) dark matter model. In our proposal, AQNs can cross the Earth and emit high energy photons at their exit. We show that the emitted spectrum is consistent with (Fraser et al. 2014), and that our calculation is not sensitive to the specific details of the model. Our proposal predicts a large seasonal variation, on the level of 20-25%, much larger than conventional dark matter models (1-10%). Since the AQN emission spectrum extends up to $\sim$ 100 keV, well beyond the keV sensitivity of XMM-Newton, we predict the AQN contribution to the hard X-ray and $\gamma$-ray backgrounds in the Earth's environment. The Gamma-Ray Burst Monitor (GBM) instrument, aboard the FERMI telescope, is sensitive to the 8 keV-40 MeV energy band. The NuSTAR (Nuclear Spectroscopic Telescope Array) is a NASA space based X ray telescope which operates in the range 3 to 79 keV is also sensitive to higher energy bands. We suggest that the multi-year archival data from the GBM or NuSTAR could be used to search for a seasonal variation in the near-Earth environment up to 100 keV as a future test of the AQN framework.

    ↳ astro-ph.HEastro-ph.EPhep-phPhys.Dark Univ.(2022)·19 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.