Fri·Apr 6, 2018Friday·April 6, 2018

1. 01*

   Natural Alignment of Quark Flavors and Radiatively Induced Quark Mixings

   Abhish Dev🇺🇸 · Rabindra N. Mohapatra🇺🇸

   The standard model does not provide an explanation of the observed alignment of quark flavors i.e. why are the up and down quarks approximately aligned in their weak interactions according to their masses? We suggest a resolution of this puzzle using a combination of left-right and Peccei-Quinn (PQ) symmetry. The quark mixings in this model vanish at the tree level and arise out of one loop radiative corrections which explains their smallness. The lepton mixings on the other hand appear at the tree level and are therefore larger. We show that all fermion masses and mixings can be fitted with a reasonable choice of parameters. The neutrino mass fit using seesaw mechanism requires the right handed $W_R$ mass bigger than 18 TeV. Due to the presence of PQ symmetry, this model clearly provides a solution to the strong CP problem.

   hep-phPRD(2018)·11 citations
2. 02*

   Casting a Wide Signal Net with Future Direct Dark Matter Detection Experiments

   Graciela B. Gelmini🇺🇸 · Volodymyr Takhistov🇺🇸 · Samuel J. Witte🇪🇸

   As dark matter (DM) direct detection experiments continue to improve their sensitivity they will inevitably encounter an irreducible background arising from coherent neutrino scattering. This so-called "neutrino floor" may significantly reduce the sensitivity of an experiment to DM-nuclei interactions, particularly if the recoil spectrum of the neutrino background is approximately degenerate with the DM signal. This occurs for the conventionally considered spin-independent (SI) or spin-dependent (SD) interactions. In such case, an increase in the experiment's exposure by multiple orders of magnitude may not yield any significant increase in sensitivity. The typically considered SI and SD interactions, however, do not adequately reflect the whole landscape of the well-motivated DM models, which includes other interactions. Since particle DM has not been detected yet in laboratories, it is essential to understand and maximize the detection capabilities for a broad variety of possible models and signatures. In this work we explore the impact of the background arising from various neutrino sources on the discovery potential of a DM signal for a large class of viable DM-nucleus interactions and several potential futuristic experimental settings, with different target elements. For some momentum suppressed cross sections, large DM particle masses and heavier targets, we find that there is no suppression of the discovery limits due to neutrino backgrounds. Further, we explicitly demonstrate that inelastic scattering, which could appear in models with multicomponent dark sectors, would help to lift the signal degeneracy associated with the neutrino floor. This study could assist with mapping out the optimal DM detection strategy for the next generation of experiments.

   hep-phastro-ph.COJCAP(2018)·64 citations
3. 03*

   SU(3) symmetry breaking in charmed baryon decays

   C.Q. Geng🇨🇳 · Y.K. Hsiao🇨🇳 · Chia-Wei Liu🇹🇼 · Tien-Hsueh Tsai🇹🇼

   We explore the breaking effects of the $SU(3)$ flavor symmetry in the singly Cabibbo-suppressed anti-triplet charmed baryon decays of ${\mathbf{B}}_c\to {\mathbf{B}}_{n}M$, with ${\mathbf{B}}_c=({\Xi }_c^0,{\Xi }_c^{+},{\Lambda }_c^{+})$ and ${\mathbf{B}}_n(M)$ the baryon (pseudo-scalar) octets. We find that these breaking effects can be used to account for the experimental data on the decay branching ratios of $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^0{K}^{+},{\Lambda }^0{K}^{+})$ and $R_{K/\pi }^{\prime }$=$\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{K}^{+})$/$\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})$. In addition, we obtain that $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{K}^{+},{\Sigma }^{-}{\pi }^{+})=(4.6\pm 1.7,12.8\pm 3.1)\times 10^{-4}$, $\mathcal{B}({\Xi }_c^0\to p{K}^{-},{\Sigma }^{+}{\pi }^{-})=(3.0\pm 1.0,5.2\pm 1.6)\times 10^{-4}$ and $\mathcal{B}({\Xi }_c^{+}\to {\Sigma }^{0(+)}{\pi }^{+(0)})=(10.3\pm 1.7)\times 10^{-4}$, which all receive significant contributions from the breaking effects, and can be tested by the BESIII and LHCb experiments.

   hep-phhep-exEPJC(2018)·51 citations
4. 04*

   The strong decays of the light scalar mesons $f_0(500)$ and $f_0(980)$

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

   The partial width of the decay channels $f_0(500)\to \pi \pi$, $f_0(980)\to \pi \pi$ and $f_0(980)\to K\bar{K}$ are calculated using QCD light-cone sum rules method and a technique of the soft meson approximation. The scalar particles are treated as mixtures of the heavy $|H⟩=([su][\bar{s}\bar{u}]+[sd][\bar{s}\bar{d}])/\sqrt{2}$ and light $|L⟩=[ud][\bar{u}\bar{d}]$ scalar diquark-antidiquark components. Obtained results for the full width of the $f_0(500)$ meson ${\Gamma }_{\mathrm{th}.}=434.7\pm 72.3\mathrm{MeV}$ and for the $f_0(980)$ meson ${\Gamma }_{th.}=42.12\pm 6.70\mathrm{MeV}$ are compared with the world averages for these parameters, and a reasonable agreement between them is found.

   hep-phhep-exhep-latPLB(2018)·11 citations
5. 05*

   Low-energy limit of the $O(4)$ quark-meson model from the functional renormalization group approach

   Jürgen Eser🇩🇪 · Florian Divotgey🇩🇪 · Mario Mitter🇺🇸 · Dirk H. Rischke🇩🇪

   We compute the low-energy limit of the $O(4)$-symmetric quark-meson model as an effective field theory for Quantum Chromodynamics within the Functional Renormalization Group (FRG) approach. In particular, we analyze the renormalization group flow of momentum-dependent pion self-interactions beyond the local potential approximation. The numerical results for these couplings obtained from the FRG are confronted with a recent tree-level study. Additionally, their effect on the wave-function renormalization and the curvature masses is investigated.

   hep-phhep-thPRD(2018)·28 citations
6. 06*

   Neutrino Mass, Coupling Unification, Verifiable Proton Decay, Vacuum Stability and WIMP Dark Matter in SU(5)

   Biswonath Sahoo🇮🇳 · Mainak Chakraborty🇮🇳 · M.K. Parida (Siksha 'O' Anusandhan)🇮🇳

   Nonsupersymmetric minimal SU(5) with Higgs representations ${24}_H$ and $5_H$ and standard fermions in ${\bar{5}}_F\oplus {10}_F$ is well known for its failure in unification of gauge couplings and lack of predicting neutrino masses. Like standard model, it is also affected by the instability of the Higgs scalar potential. We note that extending the Higgs sector by ${75}_H$ and ${15}_H$ not only leads to the popular type-II seesaw ansatz for neutrino masses with a lower bound on the triplet mass $M_{\Delta }>2\times 10^9$ GeV, but also achieves precision unification of gauge couplings without proliferation of non-standard light Higgs scalars or fermions near the TeV scale. Consistent with recent LUX-2016 lower bound, the model easily accommodates a singlet scalar WIMP dark matter near the TeV scale which resolves the vacuum stability issue even after inclusion of heavy triplet threshold effect. We estimate proton lifetime predictions for $p\to e^{+}{\pi }^0$ including uncertainties due to input parameters and threshold effects due to superheavy Higgs scalars and superheavy $X^{\pm 4/3},Y^{\pm 1/3}$ gauge bosons. The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper Kamiokande experiments.

   hep-phAdv.High Energy Phys.(2018)·5 citations
7. 07*

   Coherent lepton pair production in hadronic heavy ion collisions

   W. Zha🇨🇳 · L. Ruan🇺🇸 · Z. Tang🇨🇳 · Z. Xu🇺🇸 · S. Yang🇺🇸

   Recently, significant enhancements of $e^{+}{e}^{-}$ pair production at very low transverse momentum ($p_T<0.15$ GeV/c) were observed by the STAR collaboration in peripheral hadronic A+A collisions. This excesses can not be described by the QGP thermal radiation and $\rho$ in-medium broadening calculations. This is a sign of coherent photon-photon interactions, which were conventionally studied only in ultra-peripheral collisions. In this article, we present calculations of lepton pair ($e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$) production from coherent photon-photon interactions in hadronic A+A collisions at RHIC and LHC energies within the STAR and ALICE acceptance.

   hep-phPLB(2018)·61 citations
8. 08*

   The $S3$ Symmetric Model with a Dark Scalar

   C. Espinoza🇲🇽 · E. A. Garcés🇲🇽 · M. Mondragón🇲🇽 · H. Reyes-González🇫🇷

   We study the $S3$ symmetric extension of the Standard Model in which all the irreducible representations of the permutation group are occupied by $SU(2)$ scalar doublets, one of which is taken as inert and can lead to dark matter candidates. We perform a scan over parameter space probing points against physical constraints ranging from unitarity tests to experimental Higgs searches limits. We find that the latter constraints severely restrict the parameter space of the model. For acceptable points we compute the value of the relic density of the dark scalar candidates and find that it has a region for low dark matter masses which complies with the Higgs searches bounds and lies within the experimental Planck limit. For masses $\gtrsim 80$ GeV the value of the relic density is below the Planck bound, and it reaches values close to it for very heavy masses $\sim 5$ TeV. In this heavy mass region, this opens the interesting possibility of extending the dark sector of the model with additional particles.

   hep-phPLB(2019)·25 citations
9. 09*

   Probing the Color Structure of the Perfect QCD Fluids via Soft-Hard-Event-by-Event Azimuthal Correlations

   Shuzhe Shi🇺🇸 · Jinfeng Liao🇺🇸 · Miklos Gyulassy🇺🇸

   We develop a comprehensive dynamical framework, CIBJET, to calculate on an event-by-event basis the dependence of correlations between soft ($p_T<2$ Gev) and hard ($p_T>10$ Gev) azimuthal flow angle harmonics on the color composition of near-perfect QCD fluids produced in high energy nuclear collisions at RHIC and LHC. CIBJET combines consistently predictions of event-by-event VISHNU2+1 viscous hydrodynamic fluid fields with CUJET3.1 predictions of event-by-event jet quenching. We find that recent correlation data favor a temperature dependent color composition including bleached chromo-electric $q(T)+g(T)$ components and an emergent chromo-magnetic degrees of freedom $m(T)$ consistent with non-perturbative lattice QCD information in the confinement/deconfinement temperature range.

   hep-phCPC(2018)·43 citations
10. 10*

    Gauged $U(1)$ Clockwork

    Hyun Min Lee🇰🇷

    We review the gauged $U(1)$ clockwork models as portals for new physics to obtain effectively hierarchical couplings of the Standard Model (SM) particles from genuine couplings of order one. Nearest-neighbor mass mixing between multiple $U(1)$ gauge bosons lead to the localization of the zero mode gauge boson, realizing the milicharged gauge boson in the effective theory. We discuss some of interesting examples utilizing the gauged clockwork beyond the SM.

    hep-phhep-thPoS(2018)·1 citation
11. 11*

    Naumov- and Toshev-like relations in the renormalization-group evolution of quarks and Dirac neutrinos

    Zhi-zhong Xing🇨🇳 · Shun Zhou🇨🇳

    In an analytical way of studying matter effects on neutrino oscillations, the Naumov and Toshev relations have been derived to respectively link the Jarlskog invariant of CP violation and the Dirac phase in the standard parametrization of the $3\times 3$ flavor mixing matrix to their matter-corrected counterparts. Here we show that there exist similar relations for Dirac neutrinos and charged leptons evolving with energy scales via the one-loop renormalization-group (RG) equations in the tau-dominance approximation, and for the running behaviors of up- and down-type quarks in the top-dominance approximation, provided a different parametrization is taken into account.

    hep-phCPC(2018)·5 citations
12. 12*

    First Monte Carlo global QCD analysis of pion parton distributions

    P. C. Barry🇺🇸 · N. Sato🇺🇸 · W. Melnitchouk🇺🇸 · Chueng-Ryong Ji🇺🇸

    We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, combining $\pi A$ Drell-Yan data with leading neutron electroproduction from HERA within a Monte Carlo approach based on nested sampling. Inclusion of the HERA data allows the pion PDFs to be determined down to much lower values of $x$, with relatively weak model dependence from uncertainties in the chiral splitting function. The combined analysis reveals that gluons carry a significantly higher pion momentum fraction, $\sim 30\%$, than that inferred from Drell-Yan data alone, with sea quarks carrying a somewhat smaller fraction, $\sim 15\%$, at the input scale. Within the same effective theory framework, the chiral splitting function and pion PDFs can be used to describe the $\bar{d}-\bar{u}$ asymmetry in the proton.

    hep-phhep-exnucl-thPRL(2018)·200 citations
13. 13*

    Spectral function for overoccupied gluodynamics from real-time lattice simulations

    K. Boguslavski🇫🇮 · A. Kurkela🇨🇭 · T. Lappi🇫🇮 · J. Peuron🇫🇮

    We study the spectral properties of a highly occupied non-Abelian non-equilibrium plasma appearing ubiquitously in weak coupling descriptions of QCD matter. The spectral function of this far-from-equilibrium plasma is measured by employing linear response theory in classical-statistical real-time lattice Yang-Mills simulations. We establish the existence of transversely and longitudinally polarized quasiparticles and obtain their dispersion relations, effective mass, plasmon frequency, damping rate and further structures in the spectral and statistical functions. Our new method can be interpreted as a non-perturbative generalization of hard thermal loop (HTL) effective theory. We see indications that our results approach leading order HTL in the appropriate limit. The method can also be employed beyond the range of validity of HTL.

    hep-phhep-latnucl-thPRD(2018)·73 citations
14. 14*

    Constraining Axion-Like-Particles with Hard X-ray Emission from Magnetars

    Jean-François Fortin🇨🇦 · Kuver Sinha🇺🇸

    Axion-like particles (ALPs) produced in the core of a magnetar will convert to photons in the magnetosphere, leading to possible signatures in the hard X-ray band. We perform a detailed calculation of the ALP-to-photon conversion probability in the magnetosphere, recasting the coupled differential equations that describe ALP-photon propagation into a form that is efficient for large scale numerical scans. We show the dependence of the conversion probability on the ALP energy, mass, ALP-photon coupling, magnetar radius, surface magnetic field, and the angle between the magnetic field and direction of propagation. Along the way, we develop an analytic formalism to perform similar calculations in more general $n$-state oscillation systems. Assuming ALP emission rates from the core that are just subdominant to neutrino emission, we calculate the resulting constraints on the ALP mass versus ALP-photon coupling space, taking SGR 1806-20 as an example. In particular, we take benchmark values for the magnetar radius and core temperature, and constrain the ALP parameter space by the requirement that the luminosity from ALP-to-photon conversion should not exceed the total observed luminosity from the magnetar. The resulting constraints are competitive with constraints from helioscope experiments in the relevant part of ALP parameter space.

    hep-phastro-ph.HEJHEP(2018)·64 citations
15. 15*

    An effective holographic approach to QCD

    Alfonso Ballon-Bayona🇧🇷 · Henrique Boschi-Filho🇧🇷 · Luis A. H. Mamani🇧🇷 · Alex S. Miranda🇧🇷 · Vilson T. Zanchin🇧🇷

    We describe a holographic approach to QCD where conformal symmetry is broken explicitly in the UV by a relevant operator $\mathcal{O}$. The operator maps to a 5d scalar field, the dilaton, with a massive term. Implementing also the IR constraint found by Gursoy, Kiritsis and Nitti, an approximate linear glueball spectrum is obtained which is consistent with lattice data. Finally, we describe the evolution of the model parameters with the conformal dimension of $\mathcal{O}$. This suggests a map between the QCD trace anomaly and the trace Ward identity of deformed conformal field theories.

    ↳ hep-thhep-lathep-ph6 citations
16. 16*

    Finite density condensation and scattering data - a study in ${\varphi }^4$ lattice field theory

    Christof Gattringer🇦🇹 · Mario Giuliani🇦🇹 · Oliver Orasch🇦🇹

    We study the quantum field theory of a charged ${\varphi }^4$ field in lattice regularization at finite density and low temperature in 2 and 4 dimensions with the goal of analyzing the connection of condensation phenomena to scattering data in a non-perturbative way. The sign problem of the theory at non-zero chemical potential $\mu$ is overcome by using a worldline representation for the Monte Carlo simulation. At low temperature we study the particle number as a function of $\mu$ and observe the steps for $\text{mbox}1-,$ 2- and 3-particle condensation. We determine the corresponding critical values ${\mu }_n^{crit},n=1,2,3$ and analyze their dependence on the spatial extent $L$ of the lattice. Linear combinations of the ${\mu }_n^{crit}$ give the interaction energies in the 2- and 3-particle sectors and their dependence on $L$ is related to scattering data by Lüscher's formula and its generalizations to three particles. For 2-$d$ we determine the scattering phase shift and for 4-$d$ the scattering length. We cross-check our results with a determination of the mass and the 2- and 3-particle energies from conventional 2-, 4-, and 6-point correlators at zero chemical potential. The letter demonstrates that the physics of condensation at finite density and low temperature is closely related to scattering data of a quantum field theory.

    ↳ hep-lathep-phPRL(2018)·5 citations
17. 17*

    Modified Starobinsky Inflation

    Seokcheon Lee🇰🇷

    Starobinsky has suggested an inflation model which is obtained from the vacuum Einstein's equations modified by the one-loop corrections due to quantized matter fields. Although the one-loop gravitational action is not known for a general FRW background, it can be obtained in a de Sitter space to give ${\text{Mp}}^{2}R+\alpha R^2+\beta R^2\ln (R/M^2)$. Thus, one needs to investigate the inflationary behavior of this model compared to the Starobinsky model (i.e. $\beta =0$). The coefficient $\alpha$ can be changed by varying the renormalization scale $M^2$ and $\beta$ is obtained from the quantum anomaly which is related to the numbers of quantum fields. It has been assumed that $\alpha \gg \beta$. We investigate the viable values of $\alpha$ and $\beta$ based on the CMB observation. We also scrutinize the reheating process in this model.

    ↳ astro-ph.COhep-ph2 citations
18. 18*

    Constituent-quark model with pionic contributions: electromagnetic $N\to \Delta$ transition

    Ju-Hyun Jung🇦🇹 · Wolfgang Schweiger🇦🇹 · Elmar P. Biernat🇵🇹

    We report on ongoing work to determine the pion-cloud contribution to the electromagnetic $N\to \Delta$ transition form factors. The starting point is an $SU(6)$ spin-flavor symmetric constituent-quark model with instantaneous confinement that is augmented by dynamical pions which couple directly to the quarks. This system is treated in a relativistically invariant way within the framework of point-form quantum mechanics using a multichannel formulation. The first step is to determine the electromagnetic form factors of the bare particles that consist only of three quarks. These form factors are basic ingredients for calculating the pion-cloud contributions. Already without the pion cloud, electromagnetic nucleon and $N\to \Delta$ transition form factors compare reasonably well with the data. By inclusion of the pion-cloud contribution coming from the $\pi$-$N$ intermediate state the reproduction of the data is further improved.

    ↳ nucl-thhep-phFew Body Syst.(2019)·2 citations
19. 19*

    Halometry from Astrometry

    Ken Van Tilburg🇺🇸 · Anna-Maria Taki🇺🇸 · Neal Weiner🇺🇸

    Halometry---mapping out the spectrum, location, and kinematics of nonluminous structures inside the Galactic halo---can be realized via variable weak gravitational lensing of the apparent motions of stars and other luminous background sources. Modern astrometric surveys provide unprecedented positional precision along with a leap in the number of cataloged objects. Astrometry thus offers a new and sensitive probe of collapsed dark matter structures over a wide mass range, from one millionth to several million solar masses. It opens up a window into the spectrum of primordial curvature fluctuations with comoving wavenumbers between $5{\text{Mpc}}^{-1}$ and $10^5{\text{Mpc}}^{-1}$, scales hitherto poorly constrained. We outline detection strategies based on three classes of observables---multi-blips, templates, and correlations---that take advantage of correlated effects in the motion of many background light sources that are produced through time-domain gravitational lensing. While existing techniques based on single-source observables such as outliers and mono-blips are best suited for point-like lens targets, our methods offer parametric improvements for extended lens targets such as dark matter subhalos. Multi-blip lensing events may also unveil the existence, location, and mass of planets in the outer reaches of the Solar System, where they would likely have escaped detection by direct imaging.

    ↳ astro-ph.COastro-ph.GAastro-ph.IMhep-phJCAP(2018)·98 citations
20. 20*

    Implicit schemes for real-time lattice gauge theory

    Andreas Ipp🇦🇹 · David Müller🇦🇹

    We develop new gauge-covariant implicit numerical schemes for classical real-time lattice gauge theory. A new semi-implicit scheme is used to cure a numerical instability encountered in three-dimensional classical Yang-Mills simulations of heavy-ion collisions by allowing for wave propagation along one lattice direction free of numerical dispersion. We show that the scheme is gauge covariant and that the Gauss constraint is conserved even for large time steps.

    ↳ hep-lathep-phnucl-thEPJC(2018)·22 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.