Wed·Jan 30, 2019Wednesday·January 30, 2019

1. 01*

   Smallest Halos in Thermal Wino Dark Matter

   Shin'ichiro Ando🇳🇱 · Ayuki Kamada🇰🇷 · Toyokazu Sekiguchi🇯🇵 · Tomo Takahashi🇯🇵

   (Mini) split supersymmetry explains the observed Higgs mass and evades stringent constraints, while keeping good features of TeV-scale supersymmetry other than the little hierarchy problem. Such scenarios naturally predict thermal wino dark matter whose mass is around $3\mathrm{TeV}$. Its non-perturbatively enhanced annihilation is a promising target of indirect detection experiments. It is known that identifying the smallest halos is essential for reducing an uncertainty in interpreting indirect detection experiments. Despite its importance, the smallest halos of thermal wino dark matter have not been well understood and thus are investigated in this work. In particular, we remark on two aspects: 1) the neutral wino is in kinetic equilibrium with primordial plasma predominantly through inelastic processes involving the slightly heavier charged wino; and 2) the resultant density contrast shows larger powers at dark acoustic oscillation peaks than in cold dark matter, which is known as an overshooting phenomenon. By taking them into account, we provide a rigorous estimate of the boost factor. Our result facilitates accurately pinning down thermal wino dark matter through vigorous efforts in indirect detection experiments.

   hep-phastro-ph.COPRD(2019)·7 citations
2. 02*

   Higgs-mediated bound states in dark-matter models

   Julia Harz🇩🇪 · Kalliopi Petraki🇫🇷

   It has been recently demonstrated that the 125 GeV Higgs boson can mediate a long-range force between TeV-scale particles, that can impact considerably their annihilation due to the Sommerfeld effect, and hence the density of thermal relic dark matter. In the presence of long-range interactions, the formation and decay of particle-antiparticle bound states can also deplete dark matter significantly. We consider the Higgs boson as mediator in the formation of bound states, and compute the effect on the dark matter abundance. To this end, we consider a simplified model in which dark matter co-annihilates with coloured particles that have a sizeable coupling to the Higgs. The Higgs-mediated force affects the dark matter depletion via bound state formation in several ways. It enhances the capture cross-sections due to the attraction it mediates between the incoming particles, it increases the binding energy of the bound states, hence rendering their ionisation inefficient sooner in the early universe, and for large enough couplings, it can overcome the gluon repulsion of certain colour representations and give rise to additional bound states. Because it alters the momentum exchange in the bound states, the Higgs-mediated force also affects the gluon-mediated potential via the running of the strong coupling. We comment on the experimental implications and conclude that the Higgs-mediated potential must be taken into account when circumscribing the viable parameter space of related models.

   hep-phJHEP(2019)·44 citations
3. 03*

   U(1)' coupling constant at low energies from heterotic orbifolds

   Yessenia Olguin-Trejo🇲🇽 · Omar Perez-Figueroa🇲🇽 · Ricardo Perez-Martinez🇲🇽 · Saul Ramos-Sanchez🇲🇽

   Additional Abelian gauge interactions are generic to string compactifications. In heterotic string models, gauge coupling unification of such forces and other gauge interactions is natural due to their common origin. In this letter we study systematically the 1-loop running of the coupling constants in effective vacua emerging from Z8 heterotic orbifold compactifications that provide the matter spectrum of the MSSM plus some vectorlike exotics, restricting to vacua that yield a non-anomalous U(1)' symmetry, gauge coupling unification and the observed values of known gauge couplings. We determine the low-energy value of the U(1)' coupling constant for different scales of supersymmetry breakdown. We find that the U(1)' coupling constant is quite restricted in string models to lie in the range 0.46-0.7 for low-scale supersymmetry or 0.44-0.6 in other cases. We argue that the phenomenology of these string vacua should be further explored to solve some extant issues, such as the stability of the Higgs vacuum.

   hep-phPLB(2019)·4 citations
4. 04*

   $\rho \rho$ scattering revisited with coupled-channels of pseudoscalar mesons

   Zheng-Li Wang🇨🇳 · Bing-Song Zou🇨🇳

   The $\rho \rho$ scattering has been studied by two groups which both claimed a dynamical generated scalar meson, most likely to be $f_0(1370)$. Here we investigate the influence of coupled-channels of pseudoscalar mesons, i.e., $\pi \pi$ and $\bar{K}K$, on this dynamical generated scalar state. With the coupled channel effect included, the pole and partial decay widths are found to be more close to PDG values for $f_0(1500)$.

   hep-phPRD(2019)·13 citations
5. 05*

   Power corrections to the pion transition form factor from higher-twist distribution amplitudes of photon

   Yue-Long Shen🇨🇳 · Jing Gao🇨🇳 · Cai-Dian Lü🇨🇳 · Yan Miao🇨🇳

   In this paper we investigate the power suppressed contributions from two-particle and three-particle twist-4 light-cone distribution amplitudes (LCDAs) of photon within the framework of light-cone sum rules. Compared with leading twist LCDA result, the contribution from three-particle twist-4 LCDAs is not suppressed in the expansion by $1/Q^2$, so that the power corrections considered in this work can give rise to a sizable contribution, especially at low $Q^2$ region. According to our result, the power suppressed contributions should be included in the determination of the Gegenbauer moments of pion LCDAs with the pion transition form factor.

   hep-phPRD(2019)·11 citations
6. 06*

   Scherk-Schwarz orbifolds at the LHC

   Dumitru Dan Smaranda🇬🇧 · David J Miller🇬🇧

   We examine orbifold theories of Grand Unification with Scherk-Schwarz twisting, performing a renormalisation group analysis and applying low energy experimental constraints. We rule out the minimal SU(5) models, and consider simple extensions including additional fields, such as an additional scalar field, or additional symmetries, such as $SU(5)\times U(1)$ or $E_6$. We find that it is very difficult to generate a large enough Higgs mass while simultaneously passing LHC experimental search constraints.

   hep-phhep-thPRD(2019)·2 citations
7. 07*

   Dynamics of the quark-antiquark interaction and the universality of Regge trajectories

   A.M. Badalian🇷🇺 · B.L.G. Bakker🇳🇱

   The dynamical picture of a quark-antiquark interaction in light mesons, which provides linearity of radial and orbital Regge trajectories (RT), is studied with the use of the relativistic string Hamiltonian with flattened confining potential and taking into account the self-energy and string corrections. Due to the flattening effect both slopes, ${\beta }_n$ of the radial and ${\beta }_l$ of the orbital RT, decrease by $\sim 30\%$ with the value of ${\beta }_n=1.30(5)$~GeV${}^2$ being larger than ${\beta }_l=0.95(5)$~GeV. The self-energy correction provides the linearity of RT and remains important up to very high excitations; the string correction decreases the slope of the orbital RT, while the intercept ${\beta }_0=0.51(1)$GeV${}^2$ is equal to the squared centroid mass of $\rho (1S)$. If the universal gluon-exchanged potential without fitting parameters and screening function, as in heavy quarkonia, is taken, then the slope of the radial RT decreases, ${\beta }_n=1.15(8)$~GeV${}^2$, and its value coincides with the slope of the orbital RT, ${\beta }_l=1.08(8)$~GeV${}^2$ within theoretical errors, producing the universal RT.

   hep-phhep-exPRD(2019)·17 citations
8. 08*

   Renormalization Group Evolution of Dimension-seven Operators in Standard Model Effective Field Theory and Relevant Phenomenology

   Yi Liao (Nankai Univ and CHEP Peking Univ)🇨🇳 · Xiao-Dong Ma (Nankai Univ)🇨🇳

   We showed in a previous publication that there are six independent dimension-seven operators violating both lepton and baryon numbers ($L=-B=1$) and twelve ones violating lepton but preserving baryon number ($L=2,B=0$) in standard model effective field theory, and we calculated one-loop renormalization for the former six operators. In this work we continue our efforts on renormalization of the operators. It turns out this could become subtle because the operators are connected by nontrivial relations when fermion flavors are counted. This kind of relations does not appear in lower dimensional operators. We show how we can extract anomalous dimension matrix for a flavor-specified basis of operators from counterterms computed for the above flavor-blind operators without introducing singular inverse Yukawa coupling matrices. As a phenomenological application, we investigate renormalization group effects on nuclear neutrinoless double $\beta$ decay. We also discuss very briefly its analog in the meson sector, $K^{\pm }\to {\pi }^{\mp }{\mu }^{\pm }{\mu }^{\pm }$, and indicate potential difficulties to compute its decay width.

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

   Spin partners $W_{bJ}$ from the line shapes of the $Z_b(10610)$ and $Z_b(10650)$

   V. Baru🇩🇪 · E. Epelbaum🇩🇪 · A. A. Filin🇩🇪 · C. Hanhart🇩🇪 · A. V. Nefediev🇷🇺 · Q. Wang🇩🇪

   In a recent paper Phys.Rev. D98, 074023 (2018), the most up-to-date experimental data for all measured production and decay channels of the bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ were analysed in a field-theoretical coupled-channel approach which respects analyticity and unitarity and incorporates both the pion exchange as well as a short-ranged potential nonperturbatively. All parameters of the interaction were fixed directly from data, and pole positions for both $Z_b$ states were determined. In this work we employ the same approach to predict in a parameter-free way the pole positions and the line shapes in the elastic and inelastic channels of the (still to be discovered) spin partners of the $Z_b$ states. They are conventionally referred to as $W_{bJ}$'s with the quantum numbers $J^{PC}=J^{++}$ ($J=0,1,2$). It is demonstrated that the results of our most advanced pionful fit, which gives the best ${\chi }^2/d.o.f.$ for the data in the $Z_b$ channels, are consistent with all $W_{bJ}$ states being above-threshold resonances which manifest themselves as well pronounced hump structures in the line shapes. On the contrary, in the pionless approach, all $W_{bJ}$'s are virtual states which can be seen as enhanced threshold cusps in the inelastic line shapes. Since the two above scenarios provide different imprints on the observables, the role of the one-pion exchange in the $B^{(\ast )}{\bar{B}}^{(\ast )}$ systems can be inferred from the once available experimental data directly.

   hep-phnucl-thPRD(2019)·54 citations
10. 10*

    On the elliptic flow of heavy quarkonia in $pA$ collisions

    Cheng Zhang🇨🇳 · Cyrille Marquet🇫🇷 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇫🇷 · Bo-Wen Xiao🇨🇳

    Using the dilute-dense factorization in the Color Glass Condensate framework, we investigate the azimuthal angular correlation between a heavy quarkonium and a charged light hadron in proton-nucleus collisions. We extract the second harmonic $v_2$, commonly known as the elliptic flow, with the light hadron as the reference. This particular azimuthal angular correlation between a heavy meson and a light hadron has first been measured at the LHC recently. The experimental results indicate that the elliptic flows for heavy-flavor mesons ($J/\psi$ and $D^0$) are almost as large as those for light hadrons. Our calculation demonstrates that this result can be naturally interpreted as an initial state effect due to the interaction between the incoming partons from the proton and the dense gluons inside the target nucleus. Since the heavy quarkonium $v_2$ exhibits a weak mass dependence according to our calculation, we predict that the heavy quarkonium ${\rm Y}$ should have a similar elliptic flow as compared to that of the $J/\psi$, which can be tested in future measurements.

    hep-phnucl-exnucl-thPRL(2019)·62 citations
11. 11*

    Looking inside jets: an introduction to jet substructure and boosted-object phenomenology

    Simone Marzani🇮🇹 · Gregory Soyez🇫🇷 · Michael Spannowsky🇬🇧

    The study of the internal structure of hadronic jets has become in recent years a very active area of research in particle physics. Jet substructure techniques are increasingly used in experimental analyses by the LHC collaborations, both in the context of searching for new physics and for Standard Model measurements. On the theory side, the quest for a deeper understanding of jet substructure algorithms has contributed to a renewed interest in all-order calculations in QCD. This has resulted in new ideas about how to design better observables and how to provide a solid theoretical description for them. In the last years, jet substructure has seen its scope extended, for example, with an increasing impact in the study of heavy-ion collisions, or with the exploration of deep-learning techniques. Furthermore, jet physics is an area in which experimental and theoretical approaches meet together, where cross-pollination and collaboration between the two communities often bear the fruits of innovative techniques. Despite the wealth of literature on this topic, we feel that a comprehensive and, at the same time, pedagogical introduction to jet substructure is still missing. This makes the endeavour of approaching the field particularly hard, as newcomers have to digest an increasing number of substructure algorithms and techniques, too often characterised by opaque terminology and jargon. Furthermore, while first-principle calculations in QCD have successfully been applied in order to understand and characterise the substructure of jets, they often make use of calculational techniques, such as resummation, which are not the usual textbook material. Thus, the idea of combining our experience in different aspects of jet substructure phenomenology to put together this set of lecture notes, which we hope could help and guide someone who moves their first steps in the physics of jet substructure.

    hep-phhep-exLect.Notes Phys.(2019)·255 citations
12. 12*

    The hadronic light-by-light contribution to the muon's anomalous magnetic moment

    Igor Danilkin🇩🇪 · Christoph Florian Redmer🇩🇪 · Marc Vanderhaeghen🇩🇪

    In view of the current 3 - 4 $\sigma$ deviation between theoretical and experimental values for the muon's anomalous magnetic moment, we review the ongoing efforts in constraining the hadronic light-by-light contribution to $a_{\mu }$ by using dispersive techniques combined with a dedicated experimental program to obtain the required hadronic input.

    hep-phhep-exPPNP(2019)·65 citations
13. 13*

    Studying gaugino masses in supersymmetric model at future 100 TeV $pp$ collider

    Shoji Asai🇯🇵 · So Chigusa🇯🇵 · Toshiaki Kaji🇯🇵 · Takeo Moroi🇯🇵 · Masahiko Saito🇯🇵 · Ryu Sawada🇯🇵 · Junichi Tanaka🇯🇵 · Koji Terashi🇯🇵 · Kenta Uno🇯🇵

    We discuss prospects of studying supersymmetric model at future $pp$ circular collider (FCC) with its centre-of-mass energy of $\sim 100\mathrm{TeV}$. We pay particular attention to the model in which Wino is lighter than other supersymmetric particles and all the gauginos are within the kinematical reach of the FCC, which is the case in a large class of so-called pure gravity mediation model based on anomaly mediated supersymmetry breaking. In such a class of model, charged Wino becomes long-lived with its decay length of $\sim 6\mathrm{cm}$, and the charged Wino tracks may be identified in particular by the inner pixel detector; the charged Wino tracks can be used not only for the discrimination of standard model backgrounds but also for the event reconstructions. We show that precise determinations of the Bino, Wino, and gluino masses are possible at the FCC. For such measurements, information about the charged Wino tracks, including the one about the velocity of the charged Wino using the time of the hit at the pixel detector, is crucial. With the measurements of the gaugino masses in the pure gravity mediation model, we have an access to more fundamental parameters like the gravitino mass.

    hep-phhep-exJHEP(2019)·4 citations
14. 14*

    High Energy Hadron Production as Self-Organized Criticality

    Paolo Castorina🇮🇹 · Helmut Satz🇩🇪

    In high energy nuclear collisions, production rates of light nuclei as well as those of hadrons and hadronic resonances agree with the predictions of an ideal gas at a temperature T = 155 +/- 10 MeV. In an equilibrium medium of this temperature, light nuclei cannot survive. We propose that the observed behavior is due to an evolution in global non-equilibrium, leading to self-organized criticality. At the confinement point, the initial quark-gluon medium becomes quenched by the vacuum, breaking up into all allowed free hadronic and nuclear mass states, without formation of any subsequent thermal hadronic medium.

    hep-phhep-exIJMPE(2019)·6 citations
15. 15*

    Rare hyperon decays with missing energy

    Jusak Tandean🇹🇼

    We explore the strangeness-changing decays of the lightest hyperons into another baryon plus missing energy within and beyond the standard model (SM). In the SM these processes arise from the loop-induced quark transition $s\to d\nu \bar{\nu }$ and their branching fractions are estimated to be less than $10^{-11}$. In the presence of new physics (NP) the rates of these hyperon decays with missing energy could increase significantly with respect to the SM expectations because of modifications to the SM process or contributions from additional modes with new invisible particles. Adopting a model-independent approach and taking into account constraints from the kaon sector, we find that the current data on $K\to \pi \nu \bar{\nu }$ do not permit sizable NP impact on the hyperon decays via underlying operators having mainly parity-even quark parts. In contrast, NP operators with primarily parity-odd quark parts are much less restricted by the existing bounds on $K\to \mathrm{invisible}$ and $K\to \pi \pi \nu \bar{\nu }$ and consequently could produce substantially amplifying effects on the hyperon modes. Their NP-enhanced branching fractions could reach levels potentially observable in the ongoing BESIII experiment.

    hep-phhep-exnucl-thJHEP(2019)·21 citations
16. 16*

    Lattice-Friendly Gauge Completion of a Composite Higgs with Top Partners

    Helene Gertov🇺🇸 · Ann E. Nelson🇺🇸 · Ashley Perko🇺🇸 · Devin G. E. Walker🇺🇸

    We give an explicit example of a composite Higgs model with a pseudo-Nambu-Goldstone Higgs in which the top Yukawa coupling is generated via the partial compositeness mechanism. This mechanism requires composite top partners which are relatively light compared to the typical mass scale of the strongly coupled theory. While most studies of the phenomenology of such models have focused on a bottom-up approach with a minimal effective theory, a top-down approach suggests that that the theory should contain a limit in which an unbroken global chiral symmetry protects the mass of the top partners, and the spectrum of the partners satisfies `t Hooft matching conditions. We therefore consider a model for the UV gauge group which could provide a solution to the matching conditions, and note that the relatively light fermions and pseudo-Goldstone bosons fall into complete multiplets of a large approximate global symmetry. This implies that the spectrum of particles lighter than a few TeV is non-minimal. Our example illustrates likely features of a composite Higgs theory, and also serves as an example of a non-chiral theory with no sign problem and a possible solution to `t Hooft matching conditions. It would therefore be very interesting for a lattice exploration. We find in this example that for some low-energy parameters in the effective theory the top partners can decay into high multiplicity final states, which could be difficult for the Large Hadron Collider (LHC) to constrain. This may potentially allow for the top partners to be lighter than those in more minimal models.

    hep-phhep-lathep-thJHEP(2019)·24 citations
17. 17*

    Axion-photon mixing in quantum field theory and vacuum energy

    A. Capolupo🇮🇹 · I. De Martino🇪🇸 · G. Lambiase🇮🇹 · An. Stabile🇮🇹

    We analyze axion--photon mixing in the framework of quantum field theory. The condensate structure of the vacuum for mixed fields induces corrections to the oscillation formulae and leads to non-zero energy of the vacuum for the component of the photon mixed with the axion. This energy generates a new effect of the vacuum polarization and it has the state equation of the cosmological constant, $w=-1$. This result holds for any homogeneous and isotropic curved space-time, as well as for diagonal metrics. Numerical estimates of the corrections to the oscillation formulae are presented by considering the intensity of the magnetic field available in the laboratory. Moreover, we estimate the vacuum energy density induced by axion--photon mixing in the Minkowski space-time. A value compatible with that of the energy density of the universe can be obtained for axions with a mass of $(10^{-3}-10^{-2})eV$ in the presence of the strong magnetic fields that characterize astrophysical objects such as pulsars or neutron stars. In addition, a value of the energy density less than that of the Casimir effect is obtained for magnetic fields used in experiments such as PVLAS. The vacuum polarization induced by this energy could be detected in next experiments and it might provide an indirect proof of the existence of the axion--photon mixing. The quantum field theory effects presented in this work may lead to new methods for studying axion-like particles.

    hep-phastro-ph.HEhep-thPLB(2019)·42 citations
18. 18*

    High-pT Signatures in Vector-Leptoquark Models

    Michael J. Baker🇨🇭 · Javier Fuentes-Martin🇨🇭 · Gino Isidori🇨🇭 · Matthias König🇨🇭

    We present a detailed analysis of the collider signatures of TeV-scale massive vector bosons motivated by the hints of lepton flavour non-universality observed in $B$-meson decays. We analyse three representations that necessarily appear together in a large class of ultraviolet-complete models: a colour-singlet ($Z^{\prime }$), a colour-triplet (the $U_1$ leptoquark), and a colour octet ($G^{\prime }$). Under general assumptions for the interactions of these exotic states with Standard Model fields, including in particular possible right-handed and flavour off-diagonal couplings for the $U_1$, we derive a series of stringent bounds on masses and couplings that constrain a wide range of explicit new-physics models.

    hep-phhep-exEPJC(2019)·144 citations
19. 19*

    Gamma Lines from the Hidden Sector

    Pavel Fileviez Perez🇺🇸 · Clara Murgui🇪🇸

    We discuss the visibility of gamma lines from dark matter annihilation. We point out a class of theories for dark matter which predict the existence of gamma lines with striking features. In these theories, the final state radiation processes are highly suppressed and one could distinguish easily the gamma lines from the continuum spectrum. We discuss the main experimental bounds and show that one could test the predictions for gamma lines in the near future in the context of simple gauge theories for dark matter.

    hep-phastro-ph.COhep-exPRD(2019)·10 citations
20. 20*

    Simplified Models of Flavourful Leptoquarks

    Ivo de Medeiros Varzielas🇵🇹 · Jim Talbert🇩🇪

    We study the implications of single leptoquark extensions of the Standard Model (SM) under the assumption that their enhanced Yukawa sectors are invariant under global Abelian flavour symmetries already present in SM mass terms. Such symmetries, assumed to be the `residual' subgroups of an ultra-violet flavour theory, have previously been considered in order to predict fermionic mixing angles. Here we focus instead on their effect on the novel flavour structures sourced by the leptoquark representations that address the present $R_{K^{(\star )}}$ anomalies in semileptonic rare $B$-decays. Combined with existing flavour data, the residual symmetries prove to be extremely constraining; we find that the (quark-lepton) leptoquark Yukawa couplings fall within $\mathcal{O}(10)$ highly predictive patterns, each with only a single free parameter, when `normal' (SM-like) hierarchies are assumed. In addition, proton decay for the scalar SU(2) triplet representation is naturally avoided in the residual symmetry approach without relying on further model building. Our results indicate that a simultaneous explanation for the $R_{K^{(\star )}}$ anomalies and the flavour puzzle may be achieved in a simplified, model-independent formalism.

    hep-phEPJC(2019)·44 citations
21. 21*

    Search for Semi-Annihilating Dark Matter with Fermi-LAT, H.E.S.S., Planck, and the Cherenkov Telescope Array

    Farinaldo S. Queiroz🇧🇷 · Clarissa Siqueira🇧🇷

    Dark matter annihilations have been fiercely restricted by the non-observation of excess events in indirect detection probes. Typically the interactions that dictate annihilation are also present in the dark matter-nucleon scattering cross section, also severely constrained by direct detection experiments. Semi-annihilations arise as a possible way to ameliorate the tension and even change the standard dark matter relic density calculation. In this work, we derive indirect detection bounds for several semi-annihilation channels including gauge bosons, the Higgs, leptophilic and leptophobic scalars. Our analysis is based on the gamma-ray observations in the direction of Dwarf Spheroidal Galaxies (Fermi-LAT) and the Galactic Center (H.E.S.S.), and Planck measurements of Cosmic Background Radiation. In addition, we derive the prospects for the Cherenkov Telescope Array (CTA) sensitivity to all these semi-annihilation modes.

    hep-phJCAP(2019)·21 citations
22. 22*

    Leggett-Garg inequality in the context of three flavour neutrino oscillation

    Javid Naikoo🇮🇳 · Ashutosh Kumar Alok🇮🇳 · Subhashish Banerjee🇮🇳 · S. Uma Sankar🇮🇳

    The present work is devoted to the characterization of the Leggett-Garg inequality for three-flavoured neutrino oscillations in presence of both matter and Charge-Conjugation and Parity violating (CP) effects. This study complements and completes the recent one put forward in [17] by relaxing the stationary condition. At variance with the latter case, the LGI contains interference terms which cannot be expressed in terms of experimentally measurable quantities, thus drawing a clear-cut distinction between the two scenarios, as well as highlighting the role of the stationary assumption on such systems. We find that the additional terms are small for high energy neutrino beam compared to the maximum value attained by the Leggett-Garg parameter.

    hep-phquant-phPRD(2019)·67 citations
23. 23*

    Meson deformation by magnetic fields in lattice QCD

    Koichi Hattori🇯🇵 · Arata Yamamoto🇯🇵

    We study light meson properties in a magnetic field, focusing on a charged pion and a charged and polarized rho meson, in quenched lattice QCD. The gauge-invariant density-density correlators are calculated to investigate the deformation caused by the magnetic field. We find that these mesons acquire elongated shapes along the magnetic field. The magnitude of the deformation is about 10-20 % when the strength of the magnetic field is of the order of the squared unphysical pion mass.

    ↳ hep-lathep-phnucl-thPTEP(2019)·16 citations
24. 24*

    Weak production of strange and charm ground-state baryons in nuclei

    J. E. Sobczyk🇪🇸 · N. Rocco🇺🇸 · A. Lovato🇺🇸 · J. Nieves🇪🇸

    We present results for the quasi-elastic weak production of $\Lambda$ and $\Sigma$ hyperons induced by $\bar{\nu }$ scattering off nuclei, in the kinematical region of interest for accelerator neutrino experiments. We employ realistic hole spectral functions and we describe the propagation of the hyperons in the nuclear medium by means of a Monte Carlo cascade. The latter strongly modifies the kinematics and the relative production rates of the hyperons, leading to a non-vanishing ${\Sigma }^{+}$ cross section, to a sizable enhancement of the $\Lambda$ production and to a drastic reduction of the ${\Sigma }^0$ and ${\Sigma }^{-}$ distributions. We also compute the quasi-elastic weak ${\Lambda }_c$ production cross section, paying special attention to estimate the uncertainties induced by the model dependence of the vacuum $n\to {\Lambda }_c$ weak matrix element. In this regard, the recent BESIII measurements of the branching ratios of ${\Lambda }_c\to \Lambda l^{+}{\nu }_l$ ($l=e,\mu$) are used to benchmark the available theoretical predictions.

    ↳ nucl-thhep-phPRC(2019)·15 citations
25. 25*

    Sensitivity study of anomalous HZZ couplings at future Higgs factory

    Hua-Dong Li🇨🇳 · Cai-Dian Lu🇨🇳 · Lian-You Shan🇨🇳

    We study the sensitivity of constraining the model independent Higgs-Z-Z coupling under effective theory up to dimension-6 operators at the future Higgs factory. Utilizing the current conceptual design parameters of the Circular Electron Positron Collider, we give the experimental limits for the model independent operators by the total Higgsstrahlung cross section and angular distribution of Z boson decay in the Higgs factory. Especially, we give very small sensitivity limit for the CP violation parameter $\tilde{g}$, which will be a clear window to test the Standard Model and look for New Physics signal.

    ↳ hep-exhep-phCPC(2019)·11 citations
26. 26*

    Evaluating Quasi-Periodic Variations in the $\gamma$-ray Lightcurves of Fermi-LAT Blazars

    F. Ait Benkhali (1)🇩🇪 · W. Hofmann (1)🇩🇪 · F.M. Rieger (1 and 2)🇩🇪 · N. Chakraborty (1 and 3) ((1) Max-Planck-Institut für Kernphysik, Germany, (2) ZAH, Institut für Theoretische Astrophysik, Universität Heidelberg, Germany, (3) Data Assimilation Research Centre, University of Reading, United Kingdom)🇩🇪

    The detection of periodicities in light curves of active galacticnuclei (AGN) could have profound consequences for our understanding of the nature and radiation physics of these objects. At high energies (HE; E>100 MeV) 5 blazars (PG 1553+113,PKS 2155-304, 0426-380, 0537-441, 0301-243) have been reported to show year-like quasi-periodic variations (QPVs) with significance >3 sig. As these findings are based on few cycles only, care needs to be taken to properly account for random variations which can produce intervals of seemingly periodic behaviour. We present results of an updated timing analysis for 6 blazars (adding PKS 0447-439), utilizing suitable methods to evaluate their long term variability properties and to search for QPVs in their light curves. We generate gamma-ray light curves covering almost 10 years, study their timing properties and search for QPVs using the Lomb-Scargle Periodogram and the Wavelet Z-transform. Extended Monte Carlo simulations are used to evaluate the statistical significance. Comparing their probability density functions (PDFs), all sources (except PG 1553+113) exhibit a clear deviation from a Gaussian distribution, but are consistent with being log-normal, suggesting that the underlying variability is of a non-linear, multiplicative nature. Apart from PKS 0301-243 the power spectral density for all investigated blazars is close to flicker noise (PL slope -1). Possible QPVs with a local significance ~ 3 sig. are found in all light curves (apart from PKS 0426-380 and 0537-441), with observed periods between (1.7-2.8) yr. The evidence is strongly reduced, however, if evaluated in terms of a global significance. Our results advise caution as to the significance of reported year-like HE QPVs in blazars. Somewhat surprisingly, the putative, redshift-corrected periods are all clustering around 1.6 yr. We speculate on possible implications for QPV generation.

    ↳ astro-ph.HEhep-phAstron.Astrophys.(2020)·38 citations
27. 27*

    Comment on "How (not) to renormalize integral equations with singular potentials in effective field theory"

    Manuel Pavon Valderrama🇨🇳

    I critically discuss two of the potential inconsistencies pointed out in the recent manuscript by Epelbaum, Gasparyan, Gegelia and Meissner, published in Eur. Phys.J. A54, 186 (2018). The potential inconsistencies are: (i) a possible mismatch between the $\hslash$ expansion of the scattering amplitude and renormalization, (ii) an impossibility of "non-perturbative renormalization" to deal with repulsive singular interactions. The conclusion is that these inconsistencies do not happen.

    ↳ nucl-thhep-phEPJA(2019)·19 citations
28. 28*

    Electromagnetic and strong isospin-breaking corrections to the muon $g-2$ from Lattice QCD+QED

    D. Giusti🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹

    We present a lattice calculation of the leading-order electromagnetic and strong isospin-breaking corrections to the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon. We employ the gauge configurations generated by the European Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ dynamical quarks at three values of the lattice spacing ($a\simeq 0.062,0.082,0.089$ fm) with pion masses between $\simeq 210$ and $\simeq 450$ MeV. The results are obtained adopting the RM123 approach in the quenched-QED approximation, which neglects the charges of the sea quarks. Quark disconnected diagrams are not included. After the extrapolations to the physical pion mass and to the continuum and infinite-volume limits the contributions of the light, strange and charm quarks are respectively equal to $\delta a_{\mu }^{\mathrm{HVP}}(ud)=7.1(2.5)\cdot 10^{-10}$, $\delta a_{\mu }^{\mathrm{HVP}}(s)=-0.0053(33)\cdot 10^{-10}$ and $\delta a_{\mu }^{\mathrm{HVP}}(c)=0.0182(36)\cdot 10^{-10}$. At leading order in ${\alpha }_{em}$ and $(m_d-m_u)/{\Lambda }_{QCD}$ we obtain $\delta a_{\mu }^{\mathrm{HVP}}(udsc)=7.1(2.9)\cdot 10^{-10}$, which is currently the most accurate determination of the isospin-breaking corrections to $a_{\mu }^{\mathrm{HVP}}$.

    ↳ hep-lathep-phPRD(2019)·188 citations
29. 29*

    SENSEI: Direct-Detection Constraints on Sub-GeV Dark Matter from a Shallow Underground Run Using a Prototype Skipper-CCD

    Orr Abramoff🇮🇱 · Liron Barak🇮🇱 · Itay M. Bloch🇮🇱 · Luke Chaplinsky🇺🇸 · Michael Crisler🇺🇸 · Dawa · Alex Drlica-Wagner🇺🇸 · Rouven Essig🇺🇸 · Juan Estrada🇺🇸 · Erez Etzion🇮🇱 · Guillermo Fernandez🇺🇸 · Daniel Gift🇺🇸 and 5 other authors

    We present new direct-detection constraints on eV-to-GeV dark matter interacting with electrons using a prototype detector of the Sub-Electron-Noise Skipper-CCD Experimental Instrument. The results are based on data taken in the MINOS cavern at the Fermi National Accelerator Laboratory. We focus on data obtained with two distinct readout strategies. For the first strategy, we read out the Skipper-CCD continuously, accumulating an exposure of 0.177 gram-days. While we observe no events containing three or more electrons, we find a large one- and two-electron background event rate, which we attribute to spurious events induced by the amplifier in the Skipper-CCD readout stage. For the second strategy, we take five sets of data in which we switch off all amplifiers while exposing the Skipper-CCD for 120k seconds, and then read out the data through the best prototype amplifier. We find a one-electron event rate of (3.51 +- 0.10) x 10^(-3) events/pixel/day, which is almost two orders of magnitude lower than the one-electron event rate observed in the continuous-readout data, and a two-electron event rate of (3.18 +0.86 -0.55) x 10^(-5) events/pixel/day. We again observe no events containing three or more electrons, for an exposure of 0.069 gram-days. We use these data to derive world-leading constraints on dark matter-electron scattering for masses between 500 keV to 5 MeV, and on dark-photon dark matter being absorbed by electrons for a range of masses below 12.4 eV.

    ↳ hep-exastro-ph.COhep-phphysics.ins-detPRL(2019)·288 citations
30. 30*

    Pixelated Dark Energy

    Jonathan J. Heckman🇺🇸 · Craig Lawrie🇺🇸 · Ling Lin🇺🇸 · Jeremy Sakstein🇺🇸 · Gianluca Zoccarato🇺🇸

    We study the phenomenology of a recent string construction with a quantum mechanically stable dark energy. A mild supersymmetry protects the vacuum energy but also allows $O(10-100)$ TeV scale superpartner masses. The construction is holographic in the sense that the 4D spacetime is generated from "pixels" originating from five-branes wrapped over metastable five-cycles of the compactification. The cosmological constant scales as $\Lambda \sim 1/N$ in the pixel number. An instability in the construction leads to cosmic expansion. This also causes more five-branes to wind up in the geometry, leading to a slowly decreasing cosmological constant which we interpret as an epoch of inflation followed by (pre-)heating when a rare event occurs in which the number of pixels increases by an order one fraction. The sudden appearance of radiation triggers an exponential increase in the number of pixels. Dark energy has a time varying equation of state with $w_a=-3{\Omega }_{m,0}(1+w_0)/2$, which is compatible with current bounds, and could be constrained further by future data releases. The pixelated nature of the Universe also implies a large-$l$ cutoff on the angular power spectrum of cosmological observables with $l_{\max }\sim O(N)$. We also use this pixel description to study the thermodynamics of de Sitter space, finding rough agreement with effective field theory considerations.

    ↳ hep-thastro-ph.COgr-qchep-phFortsch.Phys.(2019)·90 citations
31. 31*

    Constructing phase space distributions with internal symmetries

    Niklas Mueller🇺🇸 · Raju Venugopalan🇺🇸

    We discuss an ab initio world-line approach to constructing phase space distributions in systems with internal symmetries. Starting from the Schwinger-Keldysh real time path integral in quantum field theory, we derive the most general extension of the Wigner phase space distribution to include color and spin degrees of freedom in terms of dynamical Grassmann variables. The corresponding Liouville distribution for colored particles, which obey Wong's equation, has only singlet and octet components, while higher moments are fully constrained by the Grassmann algebra. The extension of phase space dynamics to spin is represented by a generalization of the Pauli-Lubanski vector; its time evolution via the Bargmann-Michel-Telegdi equation also follows from the phase space trajectories of the underlying Grassmann coordinates. Our results for the Liouville phase space distribution in systems with both spin and color are of interest in fields as diverse as chiral fluids, finite temperature field theory and polarized parton distribution functions. We also comment on the role of the chiral anomaly in the phase space dynamics of spinning particles.

    ↳ hep-thhep-phnucl-thPRD(2019)·47 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.