Mon·Apr 22, 2019Monday·April 22, 2019

1. 01*

   N${}^3$LO predictions for the decay of the Higgs boson to bottom quarks

   Roberto Mondini🇺🇸 · Matthew Schiavi🇺🇸 · Ciaran Williams🇺🇸

   We present a fully-differential calculation of the $H\to b\overline{b}$ decay at next-to-next- to-next-to-leading order (N${}^3$LO) accuracy. Our calculation considers diagrams in which the Higgs boson couples directly to the bottom quarks, i.e. the perturbative order we consider is $\mathcal{O}({\alpha }_s^3{y}_b^2)$. In order to regulate the infrared divergences present at this order we use the Projection-to-Born technique coupled with N-jettiness slicing. After validating our methodology at next-to-next-to-leading order (NNLO) we present exclusive jet rates and differential distributions for jet observables at N3LO accuracy using the Durham jet algorithm in the Higgs rest frame.

   hep-phJHEP(2019)·74 citations
2. 02*

   $H\to b\overline{b}j$ at Next-to-Next-to-Leading Order Accuracy

   Roberto Mondini🇺🇸 · Ciaran Williams🇺🇸

   We present the calculation of the decay $H\to b\overline{b}j$ at next-to-next-to-leading order (NNLO) accuracy. We consider contributions in which the Higgs boson couples directly to bottom quarks, i.e. our predictions are accurate to order $\mathcal{O}({\alpha }_s^3{y}_b^2)$ . We calculate the various components needed to construct the NNLO contribution, including an independent calculation of the two-loop amplitudes. We compare our results for the two-loop amplitudes to an existing calculation finding agreement. We present multiple checks on our two-loop expression using the known infrared factorization properties as the emitted gluon becomes soft or collinear. We use our results to construct a Monte Carlo implementation of $H\to b\overline{b}j$ and present jet rates and differential distributions in the Higgs rest frame using the Durham jet algorithm.

   hep-phJHEP(2019)·32 citations
3. 03*

   Quark and Polyakov-loop correlations in effective models at zero and non-vanishing density

   Hubert Hansen🇫🇷 · Rainer Stiele🇮🇹 · Pedro Costa🇵🇹

   The aim of this work is to shed light on some lesser known aspects of Polyakov-loop--extended chiral models (namely the Polyakov-loop extended Nambu--Jona-Lasinio and Quark-Meson models), especially on the correlation of the quark sector with the Polyakov loop. We show that the ordering of chiral and Polyakov-loop transitions and their difference in temperature as seen in lattice QCD calculations could be realized with a critical scale of the Polyakov-loop potential that is larger than the one in pure gauge theory. The comparison of the results for the Polyakov-loop susceptibility obtained using the self-consistent medium-dependent quark mass with those obtained while keeping these masses at a fixed value allows to disentangle chiral-symmetry restoration and center-symmetry breaking effects. Furthermore, a confined chirally restored phase is identified by a plateau in the quark contribution to thermodynamics and by sigma and pion spectral functions that coincide but have a small width. We also discuss that, for some large chemical potential values, the explicit center-symmetry breaking is so strong that statistical deconfinement is realized at infinitely small temperatures. Both the missing sensitivity of the Polyakov loop to the quark mass, except at close to the chiral transition, and the Polyakov loop being zero at zero temperature at all chemical potentials, can be interpreted as indications of a missing mechanism which accounts for the quark back-reaction on the Polyakov loop.

   hep-phPRD(2020)·20 citations
4. 04*

   Photon-Dark Photon Conversions in Background Electromagnetic Fields

   Jean-François Fortin🇨🇦 · Kuver Sinha🇺🇸

   The mixing of photons with light pseudoscalars in the presence of external electromagnetic fields has been used extensively to search for axion-like-particles. A similar effect for dark photon propagating states is usually not considered due to the Landau-Yang theorem. We point out that mixing between photon and dark photon propagating states in background electromagnetic fields can indeed occur, in non-linear QED, through a four-photon vertex by integrating out the electron box diagram. Starting from the Schwinger Lagrangian, we derive the equations of motion for dark photons interacting with the Standard Model photon through gauge kinetic terms. We provide expressions for the perpendicular and parallel refractive indices in series expansions in the critical field strength, valid both in the strong and weak background field limits. We then consider mixing between the photon-dark photon propagating system in the presence of pure electric and magnetic background fields, and work out the probability of conversion when the background fields are homogeneous. We indicate outlines of the calculation in the inhomogeneous case, and finally express our results in the active-sterile basis, where we find that the mixing induced by background fields can lead to corrections to the tree-level mixing in the zero field limit that is usually considered to probe such systems. Our results may find applications for probing photon-dark photon conversions in the vicinity of neutron stars and in table-top petawatt laser experiments.

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

   Chiral perturbation theory in the environment with chiral imbalance

   A.A. Andrianov🇷🇺 · V.A. Andrianov🇷🇺 · D. Espriu🇪🇸

   We discuss the description of chiral imbalance imprint in pion matter. It is based on the Chiral Perturbation Theory supplemented by medium induced chiral chemical potential in the covariant derivative. Such an implementation of chiral imbalance recently was explored in linear sigma model inspired by QCD. The relationship between two sigma models is examined. A possible experimental detection of chiral imbalance in charged pion decays inside the fireball is pointed out.

   hep-phnucl-thActa Phys.Polon.Supp.(2020)·0 citations
6. 06*

   Physics potential of the International Axion Observatory (IAXO)

   E. Armengaud🇫🇷 · D. Attie🇫🇷 · S. Basso🇮🇹 · P. Brun🇫🇷 · N. Bykovskiy🇨🇭 · J. M. Carmona🇪🇸 · J. F. Castel🇪🇸 · S. Cebrián🇪🇸 · M. Cicoli🇮🇹 · M. Civitani🇮🇹 · C. Cogollos🇪🇸 · J. P. Conlon🇬🇧 and 79 other authors

   We review the physics potential of a next generation search for solar axions: the International Axion Observatory (IAXO). Endowed with a sensitivity to discover axion-like particles (ALPs) with a coupling to photons as small as $g_{a\gamma }\sim 10^{-12}$ GeV${}^{-1}$, or to electrons $g_{ae}\sim$10${}^{-13}$, IAXO has the potential to find the QCD axion in the 1 meV$\sim$1 eV mass range where it solves the strong CP problem, can account for the cold dark matter of the Universe and be responsible for the anomalous cooling observed in a number of stellar systems. At the same time, IAXO will have enough sensitivity to detect lower mass axions invoked to explain: 1) the origin of the anomalous "transparency" of the Universe to gamma-rays, 2) the observed soft X-ray excess from galaxy clusters or 3) some inflationary models. In addition, we review string theory axions with parameters accessible by IAXO and discuss their potential role in cosmology as Dark Matter and Dark Radiation as well as their connections to the above mentioned conundrums.

   hep-phhep-exJCAP(2019)·372 citations
7. 07*

   Topological Nambu monopole in two Higgs doublet models

   Minoru Eto🇯🇵 · Yu Hamada🇯🇵 · Masafumi Kurachi🇯🇵 · Muneto Nitta🇯🇵

   We show that a topological Nambu monopole exists as a regular solution for a large range of parameters in two Higgs doublet models, contrary to the standard model admitting only non-topological Nambu monopoles. We analyze a Higgs potential with a global $U(1)$ symmetry and a discrete symmetry ${\mathbb{Z}}_2$. The monopole is attached by two topological $Z$ strings ($Z$ flux tubes) from both sides. Despite of a trivial second homotopy group, the discrete symmetry ${\mathbb{Z}}_2$ together with a non-trivial first homotopy group for $Z$ strings topologically ensures the topological stability. After analytically constructing an asymptotic form of such a configuration, we explicitly construct a solution of the equation of motion based on a 3D numerical simulation, in which magnetic fluxes spherically emanating from the monopole at large distances are deformed in the vicinity of the monopole. Since the monopoles are expected to be abundant in the present universe, they might be observed in the current monopole searches.

   hep-phhep-thPLB(2020)·21 citations
8. 08*

   Composite Higgs and Dark Matter Model in SU(6)/SO(6)

   Giacomo Cacciapaglia🇫🇷 · Haiying Cai🇰🇷 · Aldo Deandrea🇫🇷 · Ashwani Kushwaha🇮🇳

   We consider a realisation of composite Higgs models in the context of $SU(6)/SO(6)$ symmetry, which features a custodial bi-triplet, two Higgs doublets and dark matter candidates. This model can arise from an underlying gauge-fermion theory. The general vacuum structure is explored using the top partial compositeness to generate a special vacuum characterised by a single angle aligned with the first Higgs doublet. We present the CP and Dark Matter ${\mathbb{Z}}_2$ parity in two different pNGB bases and analyse the spectra in the absence of tadpoles and tachyons. For the phenomenology, we discuss the constraints from electroweak precision tests and from a potentially light CP-odd singlet (other than the Dark Matter) in the model.

   hep-phJHEP(2019)·55 citations
9. 09*

   Gravitational probes of ultra-light axions

   Daniel Grin🇺🇸 · Mustafa A. Amin🇺🇸 · Vera Gluscevic🇺🇸 · Renée Hlǒzek🇨🇦 · David J. E. Marsh🇩🇪 · Vivian Poulin🇫🇷 · Chanda Prescod-Weinstein🇺🇸 · Tristan L. Smith🇺🇸

   The axion is a hypothetical, well-motivated dark-matter particle whose existence would explain the lack of charge-parity violation in the strong interaction. In addition to this original motivation, an `axiverse' of ultra-light axions (ULAs) with masses $10^{-33}\mathrm{eV}\lesssim m_{\mathrm{a}}\lesssim 10^{-10}\mathrm{eV}$ also emerges from string theory. Depending on the mass, such a ULA contributes to the dark-matter density, or alternatively, behaves like dark energy. At these masses, ULAs' classical wave-like properties are astronomically manifested, potentially mitigating observational tensions within the $\Lambda$CDM paradigm on local-group scales. ULAs also provide signatures on small scales such as suppression of structure, interference patterns and solitons to distinguish them from heavier dark matter candidates. Through their gravitational imprint, ULAs in the presently allowed parameter space furnish a host of observational tests to target in the next decade, altering standard predictions for microwave background anisotropies, galaxy clustering, Lyman-$\alpha$ absorption by neutral hydrogen along quasar sightlines, pulsar timing, and the black-hole mass spectrum.

   ↳ astro-ph.COgr-qchep-phhep-thBull.Am.Astron.Soc.(2019)·56 citations
10. 10*

    Theory on Hadrons in Nuclear Medium

    Su Houng Lee🇰🇷

    After decades-long attempts to measure the mass shift and understand the origin of hadron mass, it became clear that one has to analyze hadrons with small vacuum width. Also, to identify the effect of chiral symmetry breaking, one has to start by looking at chiral partners. In this talk, I will review why such consideration inevitably led us to consider $K^{\ast }$ and $K_1$ in nuclear matter [T. Song, T. Hatsuda, S H Lee, PLB792 (2019) 160-169]. With the kaon beam at JPARC, one could observe the mass shift of both particles in a nuclear target experiment. Once the masses and mass difference of $K^{\ast }$ and $K_1$ mesons are measured, we will be closer to understanding the origin of the hadron masses and the effects of chiral symmetry breaking in them.

    ↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2019)·14 citations
11. 11*

    Ultra Light Boson Dark Matter and Event Horizon Telescope Observations of M87*

    Hooman Davoudiasl🇺🇸 · Peter B. Denton🇺🇸

    The initial data from the Event Horizon Telescope (EHT) on M87${}^{\ast }$, the supermassive black hole at the center of the M87 galaxy, provide direct observational information on its mass, spin, and accretion disk properties. A combination of the EHT data and other constraints provide evidence that M87${}^{\ast }$ has a mass $\sim 6.5\times 10^9{M}_{\odot }$ and dimensionless spin parameter $|a^{\ast }|\gtrsim 0.5$. These determinations disfavor ultra light bosons of mass ${\mu }_b\sim 10^{-21}$ eV, within the range considered for fuzzy dark matter, invoked to explain dark matter distribution on $\sim$ kpc scales. Future observations of M87${}^{\ast }$ could be expected to strengthen our conclusions.

    ↳ astro-ph.COhep-phPRL(2019)·246 citations
12. 12*

    A Species or Weak-Gravity Bound for Large $N$ Gauge Theories Coupled to Gravity

    Jared Kaplan🇺🇸 · Sandipan Kundu🇺🇸

    Causality constrains the gravitational interactions of massive higher spin particles in both AdS and flat spacetime. We explore the extent to which these constraints apply to composite particles, explaining why they do not rule out macroscopic objects or hydrogen atoms. However, we find that they do apply to glueballs and mesons in confining large $N$ gauge theories. Assuming such theories contain massive bound states of general spin, we find parametric bounds in $(3+1)$ spacetime dimensions of the form $N\lesssim \frac{M_{Pl}}{{\Lambda }_{\text{QCD}}}$ relating $N$, the QCD scale, and the Planck scale. We also argue that a stronger bound replacing ${\Lambda }_{\text{QCD}}$ with the UV cut-off scale may be derived from eikonal scattering in flat spacetime.

    ↳ hep-thgr-qchep-phJHEP(2019)·25 citations
13. 13*

    DarkHistory: A code package for calculating modified cosmic ionization and thermal histories with dark matter and other exotic energy injections

    Hongwan Liu🇺🇸 · Gregory W. Ridgway🇺🇸 · Tracy R. Slatyer🇺🇸

    We present a new public Python package, DarkHistory, for computing the effects of dark matter annihilation and decay on the temperature and ionization history of the early universe. DarkHistory simultaneously solves for the evolution of the free electron fraction and gas temperature, and for the cooling of annihilation/decay products and the secondary particles produced in the process. Consequently, we can self-consistently include the effects of both astrophysical and exotic sources of heating and ionization, and automatically take into account backreaction, where modifications to the ionization/temperature history in turn modify the energy-loss processes for injected particles. We present a number of worked examples, demonstrating how to use the code in a range of different configurations, in particular for arbitrary dark matter masses and annihilation/decay final states. Possible applications of DarkHistory include mapping out the effects of dark matter annihilation/decay on the global 21cm signal and the epoch of reionization, as well as the effects of exotic energy injections other than dark matter annihilation/decay. The code is available at https://github.com/hongwanliu/DarkHistory with documentation at https://darkhistory.readthedocs.io . Data files required to run the code can be downloaded at https://doi.org/10.7910/DVN/DUOUWA .

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2020)·105 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.