Thu·Feb 15, 2018Thursday·February 15, 2018

1. 01*

   vh@nnlo-v2: New physics in Higgs Strahlung

   Robert V. Harlander🇩🇪 · Jonas Klappert🇩🇪 · Stefan Liebler🇩🇪 · Lukas Simon🇩🇪

   Introducing version 2 of the code vh@nnlo, we study the effects of a number of new-physics scenarios on the Higgs-Strahlung process. In particular, the cross section is evaluated within a general 2HDM and the MSSM. While the Drell-Yan-like contributions are consistently taken into account by a simple rescaling of the SM result, the gluon-initiated contribution is supplemented by squark-loop mediated amplitudes, and by the $s$-channel exchange of additional scalars which may lead to conspicuous interference effects. The latter holds as well for bottom-quark initiated Higgs Strahlung, which is also included in the new version of vh@nnlo. Using an orthogonal rotation of the three Higgs CP eigenstates in the 2HDM and the MSSM, vh@nnlo incorporates a simple means of CP mixing in these models. Moreover, the effect of vector-like quarks in the SM on the gluon-initiated contribution can be studied. Beyond concrete models, vh@nnlo allows to include the effect of higher-dimensional operators on the production of CP-even Higgs bosons. Transverse momentum distributions of the final state Higgs boson and invariant mass distributions of the $V\varphi$ final state for the gluon- and bottom-quark initiated contributions can be studied. Distributions for the Drell-Yan-like component of Higgs-Strahlung can be included through a link to MCFM. vh@nnlo can also be linked to FeynHiggs and 2HDMC for the calculation of Higgs masses and mixing angles. It can also read these parameters from an SLHA-file as produced by standard spectrum generators. Throughout the manuscript, we highlight new-physics effects in various numerical examples, both at the inclusive level and for distributions.

   hep-phJHEP(2018)·92 citations
2. 02*

   Higher bottomonium zoo

   Jun-Zhang Wang🇨🇳 · Zhi-Feng Sun🇨🇳 · Xiang Liu🇨🇳 · Takayuki Matsuki🇯🇵

   In this work, we study higher bottomonia up to the $nL=8S$, $6P$, $5D$, $4F$, $3G$ multiplets using the modified Godfrey-Isgur (GI) model, which takes account of color screening effects. The calculated mass spectra of bottomonium states are in reasonable agreement with the present experimental data. Based on spectroscopy, partial widths of all allowed radiative transitions, annihilation decays, hadronic transitions, and open-bottom strong decays of each state are also evaluated by applying our numerical wave functions. Comparing our results with the former results, we point out difference among various models and derive new conclusions obtained in this paper. Notably, we find a significant difference between our model and the GI model when we study $D,F$, and $G$ and $n\ge 4$ states. Our theoretical results are valuable to search for more bottomonia in experiments, such as LHCb, and forthcoming Belle II.

   hep-phEPJC(2018)·75 citations
3. 03*

   Indirect unitarity violation entangled with matter effects in reactor antineutrino oscillations

   Yu-Feng Li🇨🇳 · Zhi-zhong Xing🇨🇳 · Jing-yu Zhu🇨🇳

   If finite but tiny masses of the three active neutrinos are generated via the canonical seesaw mechanism with three heavy sterile neutrinos, the 3\times 3 Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix V will not be exactly unitary. This kind of indirect unitarity violation can be probed in a precision reactor antineutrino oscillation experiment, but it may be entangled with terrestrial matter effects as both of them are very small. We calculate the probability of \overline{\nu}_e \to \overline{\nu}_e oscillations in a good analytical approximation, and find that, besides the zero-distance effect, the effect of unitarity violation is always smaller than matter effects, and their entanglement does not appear until the next-to-leading-order oscillating terms are taken into account. Given a 20-kiloton JUNO-like liquid scintillator detector, we reaffirm that terrestrial matter effects should not be neglected but indirect unitarity violation makes no difference, and demonstrate that the experimental sensitivities to the neutrino mass ordering and a precision measurement of \theta_{12} and \Delta_{21} \equiv m^2_2 - m^2_1 are robust.

   hep-phPLB(2018)·23 citations
4. 04*

   Hadronic Paschen-Back effect

   Sachio Iwasaki🇯🇵 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵 · Tetsuya Yoshida🇯🇵

   We find a novel phenomenon induced by the interplay between a strong magnetic field and finite orbital angular momenta in hadronic systems, which is analogous to the Paschen-Back effect observed in the field of atomic physics. This effect allows the wave functions to drastically deform. We discuss anisotropic decay from the deformation as a possibility to measure the strength of the magnetic field in heavy-ion collision at LHC, RHIC and SPS, which has not experimentally been measured. As an example we investigate charmonia with a finite orbital angular momentum in a strong magnetic field. We calculate the mass spectra and mixing rates. To obtain anisotropic wave functions, we apply the cylindrical Gaussian expansion method, where the Gaussian bases to expand the wave functions have different widths along transverse and longitudinal directions in the cylindrical coordinate.

   hep-phhep-exnucl-exnucl-th+1PLB(2019)·17 citations
5. 05*

   Insisting on the role of experimental data: the pseudoscalar-pole piece to the $(g_{\mu }-2)$ and the $|V_{ub}|$ from $B\to \pi \ell {\nu }_{\ell }$ differential branching ratio

   Sergi Gonzàlez-Solís🇨🇳 · Pere Masjuan🇪🇸 · Pablo Sanchez-Puertas🇨🇿

   We employ a mathematical framework based on rational approximants in order to calculate meson form factors. The method profits from unitary, is systematic and data based, and is able to ascribe a systematic uncertainty which provides for the desired model independence. Two examples are discussed: the transition form factor entering the pseudoscalar-pole piece of the hadronic light-by-light contribution to the anomalous magnetic moment of the muon, and the $B\to \pi$ form factor participating the $B\to \pi \ell {\nu }_{\ell }$ differential branching ratios which allows to determine the $|V_{ub}|$ CKM parameter.

   hep-phhep-exPoS(2018)·1 citation
6. 06*

   The $\epsilon$-form of the differential equations for Feynman integrals in the elliptic case

   Luise Adams🇩🇪 · Stefan Weinzierl🇩🇪

   Feynman integrals are easily solved if their system of differential equations is in $\epsilon$-form. In this letter we show by the explicit example of the kite integral family that an $\epsilon$-form can even be achieved, if the Feynman integrals do not evaluate to multiple polylogarithms. The $\epsilon$-form is obtained by a (non-algebraic) change of basis for the master integrals.

   hep-phhep-thPLB(2018)·168 citations
7. 07*

   Fermion masses and flavor mixings and strong CP problem

   Y. H. Ahn🇰🇷

   For all the success of the Standard Model (SM), it is on the verge of being surpassed. In this regard we argue, by showing a minimal flavor-structured model based on the non-Abelian discrete $S{L}_2(F_3)$ symmetry, that $U(1)$ mixed-gravitational anomaly cancellation could be of central importance in constraining the fermion contents of a new chiral gauge theory. Such anomaly-free condition together with the SM flavor structure demands a condition $k_1{X}_1/2=k_2{X}_2$ with $X_i$ being a charge of $U(1{)}_{X_i}$ and $k_i$ being an integer, both of which are flavor dependent. We show that axionic domain-wall condition $N_{\mathrm{DW}}$ with the anomaly free-condition depends on both $U(1{)}_X$ charged quark and lepton flavors; the seesaw scale congruent to the scale of Peccei-Quinn symmetry breakdown can be constrained through constraints coming from astrophysics and particle physics. Then the model extended by $S{L}_2(F_3)\times U(1{)}_X$ symmetry can well be flavor-structured in a unique way that $N_{\mathrm{DW}}=1$ with the $U(1{)}_X$ mixed-gravitational anomaly-free condition demands additional Majorana fermion and the flavor puzzles of SM are well delineated by new expansion parameters expressed in terms of $U(1{)}_X$ charges and $U(1{)}_X$-$[SU(3{)}_C{]}^2$ anomaly coefficients. And the model provides remarkable results on neutrino (hierarchical mass spectra and unmeasurable neutrinoless-double-beta decay rate together with the predictions on atmospheric mixing angle and leptonic Dirac CP phase favored by the recent long-baseline neutrino experiments), QCD axion, and flavored-axion.

   hep-phNPB(2019)·11 citations
8. 08*

   Three-dimensional effective theories for the two Higgs doublet model at high temperature

   Tyler Gorda🇫🇮 · Andreas Helset🇩🇰 · Lauri Niemi🇫🇮 · Tuomas V.I. Tenkanen🇫🇮 · David J. Weir🇫🇮

   Due to the infrared problem of high-temperature field theory, a robust study of the electroweak phase transition (EWPT) requires use of non-perturbative methods. We apply the method of high-temperature dimensional reduction to the two Higgs doublet model (2HDM) to obtain three-dimensional effective theories that can be used for non-perturbative simulations. A detailed derivation of the mapping between the full four-dimensional and the effective three-dimensional theories is presented. The results will be used in future lattice studies of the 2HDM. In the limit of large mass mixing between the doublets, existing lattice results can be recycled. The results of such a study are presented in a companion paper.

   hep-phJHEP(2019)·66 citations
9. 09*

   Hard production of a Z boson plus heavy flavor jets at LHC and the intrinsic charm content of a proton

   A.V. Lipatov🇷🇺 · G.I. Lykasov🇷🇺 · M.A. Malyshev🇷🇺 · A.A. Prokhorov🇷🇺 · S.M. Turchikhin🇷🇺

   The cross section of associated production of a Z boson with heavy flavor jets in $pp$ collisions is calculated using the SHERPA Monte Carlo generator and the analytical combined QCD approach based on kt-factorization at small x and conventional collinear QCD at large x. A satisfactory description of the ATLAS and CMS data on the $p_T$ spectra of Z bosons and c-jets in the whole rapidity, y, region is shown. Searching for the intrinsic charm (IC) contribution in these processes, which could be visible at large y > 1.5, we study observables very sensitive to non-zero IC contributions and less affected by theoretical QCD scale uncertainties. One of such observables is the so-called double ratio: the ratio of the differential cross section of Z + c production in the central region of |y| < 1.5 and in the forward region 1.5 < |y| < 2.5, divided by the same ratio for Z + b production. These observables could be more promising for the search of IC at LHC as compared to the observables considered earlier.

   hep-phPRD(2018)·10 citations
10. 10*

    The relativistic chiral Lagrangian for decuplet and octet baryons at next-to-leading order

    Måns Holmberg🇸🇪 · Stefan Leupold (Uppsala U.)🇸🇪

    A complete and minimal relativistic Lagrangian is constructed at next-to-leading order for SU(3) chiral perturbation theory in the presence of baryon octet and baryon decuplet states. The Lagrangian has 13 terms for the pure decuplet sector, 6 terms for the transition sector from baryon octet to decuplet and (as already known from the literature) 16 terms for the pure octet sector. The minimal field content of 25 of these terms is meson-baryon four-point interactions. 3 terms give rise to the mass splitting for baryon octet and decuplet states, respectively. 2 terms give rise to overall mass shifts. 4 terms provide anomalous magnetic moments and a decuplet-to-octet magnetic transition moment. 1 term leads to an axial vector transition moment. It is shown that meson-baryon three-point coupling constants come in at leading order whereas no additional one appears in the minimal Lagrangian at next-to-leading order. Those low-energy constants that give rise to mass splitting and magnetic moments, respectively, are determined. Predictions are provided for radiative decays of decuplet to octet baryons.

    hep-phnucl-thEPJA(2018)·36 citations
11. 11*

    Probing neutrino coupling to a light scalar with coherent neutrino scattering

    Yasaman Farzan🇮🇷 · Manfred Lindner🇩🇪 · Werner Rodejohann🇩🇪 · Xun-Jie Xu🇩🇪

    Large neutrino event numbers in future experiments measuring coherent elastic neutrino nucleus scattering allow precision measurements of standard and new physics. We analyze the current and prospective limits of a light scalar particle coupling to neutrinos and quarks, using COHERENT and CONUS as examples. Both lepton number conserving and violating interactions are considered. It is shown that current (future) experiments can probe for scalar masses of a few MeV couplings down to the level of $10^{-4}$ $(10^{-6})$. Scalars with masses around the neutrino energy allow to determine their mass via a characteristic spectrum shape distortion. Our present and future limits are compared with constraints from supernova evolution, Big Bang nucleosynthesis and neutrinoless double beta decay. We also outline UV-complete underlying models that include a light scalar with coupling to quarks for both lepton number violating and conserving coupling to neutrinos.

    hep-phhep-exJHEP(2018)·173 citations
12. 12*

    Exciting Implications of LHC Higgs Boson Data

    Gordon Kane🇺🇸

    Naively, the LHC Higgs boson looks like a Standard Model Higgs boson, with no guidance to physics beyond the Standard Model, as has often been remarked. The data show that what was discovered is the true Higgs boson. If one includes the full information available, experimental and theoretical, there are actually four significant clues implied by data. They point toward a supersymmetric two-doublet decoupling theory, and a hierarchy problem solution via TeV scale supersymmetry. That in turn suggests an underlying compactified string/M theory with a de Sitter vacuum, so we can be confident that the low scale model has an ultraviolet completion.

    hep-phhep-exhep-th3 citations
13. 13*

    Rho-pion transition form factors in the $k_T$ factorization formulism revisited

    Jun Hua🇨🇳 · Shan Cheng🇨🇳 · Ya-lan Zhang🇨🇳 · Zhen-Jun Xiao🇨🇳

    We revisit the evaluations for the spacelike and timelike $\rho \pi$ transition form factors $F_{\rho \pi }(Q^2)$ and $G_{\rho \pi }(Q^2)$ with the inclusion of the the next-to-leading order (NLO) QCD contributions in the framework of the $k_T$ factorization theorem. The infrared divergence is regularized by the transversal momentum carried by external valence quarks, and ultimately absorbed into the meson wave functions. In the region of $Q^2⩽2{\text{GeV}}^2$, where PQCD factorization apporach applicable, the NLO contribution can bring no larger than $35\%$ enhancement to the spacelike form factor $F_{\rho \pi }(Q^2)$. For the timelike form factor derived under the kinematic exchanging symmetry, this contribution is also under control when the momentum transfer squared is large enough. We also prolong our prediction into the small $Q^2$ region by taking the Lattice QCD results into account, and subsequently obtain the coupling $g_{\rho \pi \gamma }=G_{\rho \pi }(0)=0.596$.

    hep-phPRD(2018)·9 citations
14. 14*

    First Extraction of Transversity from a Global Analysis of Electron-Proton and Proton-Proton Data

    Marco Radici🇮🇹 · Alessandro Bacchetta🇮🇹

    We present the first extraction of the transversity distribution in the framework of collinear factorization based on the global analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important for, among other things, detecting possible signals of new physics in high-precision low-energy experiments.

    hep-phhep-exnucl-exnucl-thPRL(2018)·146 citations
15. 15*

    Systematic Analysis of Dirac Neutrino Masses at Dimension Five

    Chang-Yuan Yao🇨🇳 · Gui-Jun Ding🇨🇳

    We perform a systematic study of the Dirac neutrino masses which arise from a dimension five effective operator with a singlet scalar. We identify all possible realizations of this operator at tree level and one-loop level. The corresponding predictions for the particle content and neutrino mass matrix are presented. We add a $Z_2$ symmetry to forbid the renormalizable Yukawa coupling, and non-abelian discrete flavor symmetry can be used to forbid tree level diagrams in non-genuine one-loop models. The electrically neutral particle mediating the loop diagram could be dark matter candidate. We give the possible dark matter particles and the restrictions on the parameter $\alpha$ for each model.

    hep-phPRD(2018)·60 citations
16. 16*

    PDF dependence on parameter fits from hadronic data

    Zahari Kassabov🇬🇧

    We present a discussion on the methods for extracting a given parameter from measurements of hadronic data, with particular focus on determinations of the strong coupling constant. We show that when the PDF dependency on the determination is adequately taken into account, the dispersion between the results from different measurements is significantly reduced. We speculatively propose the concept of preferred value of a parameter from a particular dataset.

    hep-phActa Phys.Polon.Supp.(2018)·1 citation
17. 17*

    Phenomenology of Colored Radiative Neutrino Mass Model and Its Implications on the Cosmic-ray Observations

    Ran Ding🇨🇳 · Zhi-Long Han🇨🇳 · Li Huang🇨🇳 · Yi Liao🇨🇳

    We extend the colored Zee-Babu model with a gauged $U(1{)}_{B-L}$ symmetry and a scalar singlet dark matter (DM) candidate $S$. The spontaneous breaking of $U(1{)}_{B-L}$ leaves a residual $Z_2$ symmetry that stabilizes the DM and generates tiny neutrino mass at the two-loop level with the color seesaw mechanism. After investigating dark matter and flavor phenomenology of this model systematically, we further focus on its imprint on two of cosmic-ray anomalies: the Fermi-LAT gamma-ray excess at the Galactic Center (GCE) and the PeV ultra-high energy (UHE) neutrino events at the IceCube. We found that the Fermi-LAT GCE spectrum can be well fitted by DM annihilation into a pair of on-shell singlet Higgs mediators while being compatible with the constraints from relic density, direct detections as well as dwarf spheroidal galaxies in the Milky Way. Although the UHE neutrino events at the IceCube could be accounted for by resonance production of a TeV-scale leptoquark, the relevant Yukawa couplings have been severely limited by current low energy flavor experiments. We then derive the IceCube limits on the Yukawa couplings by employing its latest 6-year data.

    hep-phCPC(2018)·8 citations
18. 18*

    U(1) symmetric $\alpha$-attractors

    Yusuke Yamada🇺🇸

    We present a class of supergravity $\alpha$-attractors with an approximate global U(1) symmetry corresponding to the axion direction. We also develop a multi-field generalization of these models and show that the $\alpha$-attractor models with U(1) symmetries have a dual description in terms of a two-form superfield coupled to a three-form superfield.

    ↳ hep-thgr-qchep-phJHEP(2018)·21 citations
19. 19*

    Measuring the Black Hole Mass Spectrum from Redshifts of aLIGO Binary Merger Events

    Yang Bai🇺🇸 · Vernon Barger🇺🇸 · Sida Lu🇺🇸

    The binary black hole merger events observed by the Advanced LIGO (aLIGO) and VIRGO collaboration can shed light on the origins of black holes. Many studies based on black hole stellar origins have shown a maximum mass for stellar black holes, which can be measured or constrained from the observed black hole mass distribution. In this paper, we point out that the redshift distribution of the observed merger events can provide complementary information for studying the black hole mass distribution, because the detectability correlates the event redshift to the black hole masses. Based on the five observed events and using the Kolmogorov-Smirnov test, we have found that the maximum of the stellar black hole masses are constrained to be below $76M_{\odot }$ at 90\% confidence level, for a negative power-law index of 2.3 for the heavier black hole. With the improved sensitivity of aLIGO, a few dozen merger events may be obtained, for which we estimate that the maximum mass will be constrained to $10M_{\odot }$ accuracy.

    ↳ astro-ph.HEhep-ph15 citations
20. 20*

    Chemical freezeout parameters within generic nonextensive statistics

    Abdel Nasser Tawfik (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo, WLCAPP, Cairo)🇪🇬

    The particle production in relativistic heavy-ion collisions seems to be created in a dynamically disordered system which can be best described by an extended exponential entropy. In distinguishing between the applicability of this and Boltzmann-Gibbs (BG) in generating various particle-ratios, generic (non)extensive statistics (GNS) is introduced to the hadron resonance gas model. Accordingly, the degree of (non)extensivity is determined by the possible modifications in the phase space. Both BG extensivity and Tsallis nonextensivity are included as very special cases defined by specific values of the equivalence classes $(c,d)$. We found that the particle ratios at energies ranging between $3.8$ and $2760$GeV are best reproduced by nonextensive statistics, where $c$ and $d$ range between $\sim 0.9$ and $\sim 1$. The present work aims at illustrating that the proposed approach is well capable to manifest the statistical nature of the system on interest. We don't aim at highlighting deeper physical insights. In other words, while the resulting nonextensivity is neither BG nor Tsallis, the freezeout parameters are found very compatible with BG and accordingly with the well-known freezeout phase-diagram, which is in an excellent agreement with recent lattice calculations. We conclude that the particle production is nonextensive but should not necessarily be accompanied by a radical change in the intensive or extensive thermodynamic quantities, such as internal energy and temperature. Only, the two critical exponents defining the equivalence classes $(c,d)$ are the physical parameters characterizing the (non)extensivity.

    ↳ nucl-thhep-phhep-thIndian J.Phys.(2018)·12 citations
21. 21*

    Axial Charge Fluctuation and Chiral Magnetic Effect from Stochastic Hydrodynamics

    Shu Lin🇨🇳 · Li Yan🇨🇦 · Gui-Rong Liang🇨🇳

    The amount of axial charge produced in heavy ion collisions is one of the key quantities in understanding chiral magnetic effect. Current phenomenological studies assume large axial charge chemical potential ${\mu }_5$ produced in Glasma phase and assume the conservation of axial charge throughout the evolution, which is valid in the long relaxation time limit. Based on the solution of stochastic hydrodynamics with phenomenological parameters, our study suggests that the situation of heavy ion collisions may be close to the opposite limit, in which axial charge fluctuation approaches thermodynamic limit. Using ${\mu }_5$ set by the thermodynamic limit for chiral magnetic effect and a background from parity-even $v_1$, we obtain a reasonable description of the centrality dependence of charged particle correlation measured in experiment.

    ↳ nucl-thhep-phnucl-exPRC(2018)·22 citations
22. 22*

    Interacting hadron resonance gas model in K-matrix formalism

    Ashutosh Dash🇮🇳 · Subhasis Samanta🇮🇳 · Bedangadas Mohanty🇮🇳

    An extension of Hadron Resonance Gas (HRG) model is constructed to include interactions using relativistic virial expansion of partition function. The non-interacting part of the expansion contains all the stable baryons and mesons and the interacting part contains all the higher mass resonances which decay into two stable hadrons. The virial coefficients are related to the phase shifts which are calculated using K-matrix formalism in the present work. We have calculated various thermodynamics quantities like pressure, energy density, and entropy density of the system. A comparison of thermodynamic quantities with non interacting HRG model, calculated using the same number of hadrons, shows that the results of above formalism are larger. A good agreement between equation of state calculated in K-matrix formalism and lattice QCD simulations is observed. Specifically the lattice QCD calculated interaction measure is well described in our formalism. We have also calculated second order fluctuations and correlations of conserved charges in K-matrix formalism. We observe a good agreement of second order fluctuations and baryon-strangeness correlation with lattice data below the cross-over temperature.

    ↳ nucl-thhep-phPRC(2018)·40 citations
23. 23*

    MOND and the dynamics of NGC 628

    Mordehai Milgrom🇮🇱

    Aniyan et al. (2018) have recently published direct measurements of the baryonic mass distribution and the rotation curve of the almost-face-on disc galaxy NGC 628. While its very low inclination makes this galaxy anything but ideal for rotation-curve analysis, these new results, taken at face value, have interesting ramifications for MOND. The methods employed afford a direct determination of the stellar mass in the disc, which, in turn, affords a parameter-free MOND prediction of the rotation curve, which I show. In comparison, the dark-matter fits that Aniyan et al. present have two free parameters. To boot, these results further negate an earlier claim deleterious to MOND. It is that stellar $M/L$ ratios deduced from vertical velocity dispersions in disc galaxies are rather lower than what is required by MOND fits to rotation curves. Specifically, it was claimed that even high-surface-density discs are, by and large, sub maximal; viz., that they show substantial mass discrepancies near their center. This is contrary to the prediction of MOND that in such high-acceleration regions only small discrepancies should appear, if any to speak of. Such claims of low $M/L$ values have been rebutted before, and the fallacy that may have led to them pointed out. The new results strongly buttress these rebuttals.

    ↳ astro-ph.GAastro-ph.COgr-qchep-ph3 citations
24. 24*

    Non-perturbative quark mass renormalisation and running in $N_f=3$ QCD

    Isabel Campos🇪🇸 · Patrick Fritzsch🇨🇭 · Carlos Pena🇪🇸 · David Preti🇮🇹 · Alberto Ramos🇮🇪 · Anastassios Vladikas🇮🇹

    We determine from first principles the quark mass anomalous dimension in Nf=3 QCD between the electroweak and hadronic scales. This allows for a fully non-perturbative connection of the perturbative and non-perturbative regimes of the Standard Model in the hadronic sector. The computation is carried out to high accuracy, employing massless O(a)-improved Wilson quarks and finite-size scaling techniques. We also provide the matching factors required in the renormalisation of light quark masses from lattice computations with O(a)-improved Wilson fermions and a tree-level Symanzik improved gauge action. The total uncertainty due to renormalisation and running in the determination of light quark masses in the SM is thus reduced to about 1%.

    ↳ hep-lathep-phEPJC(2018)·72 citations
25. 25*

    A Multi-Wavelength Analysis of Annihilating Dark Matter as the Origin of the Gamma-Ray Emission from M31

    Alex McDaniel🇺🇸 · Tesla Jeltema🇺🇸 · Stefano Profumo🇺🇸

    [Abridged] Indirect detection of dark matter (DM) by multi-wavelength astronomical observations provides a promising avenue for probing the particle nature of DM. In the case of DM consisting of Weakly-Interacting Massive Particles (WIMPs), self-annihilation ultimately produces observable products including $e^{\pm }$ pairs and gamma rays. The gamma rays can be detected directly, while the $e^{\pm }$ pairs can be detected by radio emission from synchrotron radiation or X-rays and soft gamma rays from inverse Compton scattering. An intriguing region to search for astrophysical signs of DM is the Galactic center (GC) of the Milky Way, due in part to an observed excess of gamma-rays that could be DM. A recent observation by the Fermi-LAT collaboration of a similar excess in the central region of the Andromeda galaxy (M31) leads us to explore the possibility of a DM-induced signal there as well. We use the RX-DMFIT tool to perform a multi-frequency analysis of potential DM annihilation emissions in M31. We consider WIMP models consistent with the GC excess and calculate the expected emission across the electromagnetic spectrum in comparison with available observational data from M31. We find that the particle models that best fit the M31 excess favor lower masses than the GC excess. The best fitting models are for a $b\bar{b}$ final state with $M_{\chi }=11$ GeV and $⟨\sigma v⟩=2.6\times 10^{-26}$ cm${}^3$s${}^{-1}$, as well as an evenly mixed $b\bar{b}/{\tau }^{+}{\tau }^{-}$ final state with $M_{\chi }=5.8$ GeV and $⟨\sigma v⟩=2.03\times 10^{-26}$ cm${}^3$s${}^{-1}$. For conservative estimates of the diffusion and magnetic field models the expected radio emissions appear to be in tension with currently available data in the central region of M31, although this constraint has a fairly strong dependence on the values chosen for parameters describing the magnetic field strength and geometry.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2018)·30 citations
26. 26*

    Hydrodynamical Neutron-star Kicks in Electron-capture Supernovae and Implications for the CRAB Supernova

    Alexandra Gessner (1,2)🇩🇪 · Hans-Thomas Janka (2) ((1) MPI for Intelligent Systems, Tuebingen, (2) MPI for Astrophysics, Garching)🇩🇪

    Neutron stars (NSs) obtain kicks of typically several 100 km/s at birth. The gravitational tug-boat mechanism can explain these kicks as consequences of asymmetric mass ejection during the supernova (SN) explosion. Support for this hydrodynamic explanation is provided by observations of SN remnants with associated NSs, which confirm the prediction that the bulk of the explosion ejecta, in particular chemical elements between silicon and the iron group, are dominantly expelled in the hemisphere opposite to the direction of the NS kick. Here, we present a large set of two- and three-dimensional explosion simulations of electron-capture SNe, considering explosion energies between ~3x10^49 erg and ~1.6x10^50 erg. We find that the fast acceleration of the SN shock in the steep density gradient delimiting the O-Ne-Mg core of the progenitor enables such a rapid expansion of neutrino-heated matter that the growth of neutrino-driven convection freezes out quickly in a high-mode spherical harmonics pattern. Since the corresponding momentum asymmetry of the ejecta is very small and the gravitational acceleration by the fast-expanding ejecta abates rapidly, the NS kick velocities are at most a few km/s. The extremely low core compactness of O-Ne-Mg-core progenitors therefore favors hydrodynamic NS kicks much below the ~160 km/s measured for the Crab pulsar. This suggests either that the Crab Nebula is not the remnant of an electron-capture SN, but of a low-mass iron-core progenitor, or that the Crab pulsar was not accelerated by the gravitational tug-boat mechanism but received its kick by a non-hydrodynamic mechanism such as, e.g., anisotropic neutrino emission.

    ↳ astro-ph.HEhep-phApJ(2018)·103 citations
27. 27*

    Planck 2015 constraints on spatially-flat dynamical dark energy models

    Junpei Ooba🇯🇵 · Bharat Ratra🇺🇸 · Naoshi Sugiyama🇯🇵

    We determine constraints on spatially-flat tilted dynamical dark energy XCDM and $\varphi$CDM inflation models by analyzing Planck 2015 cosmic microwave background (CMB) anisotropy data and baryon acoustic oscillation (BAO) distance measurements. XCDM is a simple and widely used but physically inconsistent parameterization of dynamical dark energy, while the $\varphi$CDM model is a physically consistent one in which a scalar field $\varphi$ with an inverse power-law potential energy density powers the currently accelerating cosmological expansion. Both these models have one additional parameter compared to standard $\Lambda$CDM and both better fit the TT + lowP + lensing + BAO data than does the standard tilted flat-$\Lambda$CDM model, with $\Delta {\chi }^2=-1.26(-1.60)$ for the XCDM ($\varphi$CDM) model relative to the $\Lambda$CDM model. While this is a 1.1$\sigma$ (1.3$\sigma$) improvement over standard $\Lambda$CDM and so not significant, dynamical dark energy models cannot be ruled out. In addition, both dynamical dark energy models reduce the tension between the Planck 2015 CMB anisotropy and the weak lensing ${\sigma }_8$ constraints.

    ↳ astro-ph.COgr-qchep-phhep-thAstrophys.Space Sci.(2019)·88 citations

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