Fri·Sep 16, 2016Friday·September 16, 2016

1. 01*

   Eta-Eta' mixing and the derivative of the topological susceptibility at zero momentum transfer

   N. F. Nasrallah🇱🇧

   The couplings of the isosinglet axial-vector currents to the Eta and Eta' mesons are evaluated in a stable, model independent way by use of polynomial kernels in dispersion integrals. The corrections to the Gell-Mann-Oakes-Renner relation in the isoscalar channel are deduced. The derivative of the topological susceptibility at the origin is calculated taking into account instantons and instanton screening.

   hep-phPRD(2017)·0 citations
2. 02*

   New Physics from rare decays of charm

   Alexey A Petrov🇺🇸

   Abundance of charm data in the current and future low energy flavor experiments makes it possible to study rare decays of D-mesons with ever increased precision. I discuss theoretical implications of derived constraints on New Physics models from these transitions. I argue that those constraints could be competitive with results of direct searches for New Physics particles (including Dark Matter) at the Large Hadron Collider.

   hep-phhep-exPoS(2016)·4 citations
3. 03*

   Extraction of the proton charge radius from experiments

   N. G. Kelkar🇨🇴 · T. Mart🇮🇩 · M. Nowakowski🇨🇴

   Static properties of hadrons such as their radii and other moments of the electric and magnetic distributions can only be extracted using theoretical methods and not directly measured from experiments. As a result, discrepancies between the extracted values from different precision measurements can exist. The proton charge radius, $r_p$, which is either extracted from electron proton elastic scattering data or from hydrogen atom spectroscopy seems to be no exception. The value $r_p=0.84087(39)$ fm extracted from muonic hydrogen spectroscopy is about 4% smaller than that obtained from electron proton scattering or standard hydrogen spectroscopy. The resolution of this so called proton radius puzzle has been attempted in many different ways over the past six years. The present article reviews these attempts with a focus on the methods of extracting the radius.

   hep-phnucl-thMakara Journal of Science, 20/3 (2016), 1…·3 citations
4. 04*

   Chiral medium produced by parallel electric and magnetic fields

   Marco Ruggieri🇨🇳 · Guang Xiong Peng🇨🇳 · Maxim Chernodub🇫🇷

   We compute (pseudo)critical temperature, $T_c$, of chiral symmetry restoration for quark matter in the background of parallel electric and magnetic fields. This field configuration leads to the production of a chiral medium on a time scale $\tau$, characterized by a nonvanishing value of the chiral density that equilibrates due to microscopic processes in the thermal bath. We estimate the relaxation time $\tau$ to be about $\approx 0.1-1$ fm/c around the chiral crossover; then we compute the effect of the fields and of the chiral medium on~$T_c$. We find $T_c$ to be lowered by the external fields in the chiral medium.

   hep-phhep-latnucl-thEPJ Web Conf.(2016)·10 citations
5. 05*

   Model prediction for temperature dependence of meson pole masses from lattice QCD results on meson screening masses

   Masahiro Ishii🇯🇵 · Hiroaki Kouno🇯🇵 · Masanobu Yahiro🇯🇵

   We propose a practical effective model by introducing temperature ($T$) dependence to the coupling strengths of four-quark and six-quark Kobayashi-Maskawa-'t Hooft interactions in the 2+1 flavor Polyakov-loop extended Nambu-Jona-Lasinio model. The $T$ dependence is determined from LQCD data on the renormalized chiral condensate around the pseudocritical temperature $T_c^{\chi }$ of chiral crossover and the screening-mass difference between $\pi$ and $a_0$ mesons in $T>1.1T_c^{\chi }$ where only the $U(1{)}_{\mathrm{A}}$-symmetry breaking survives. The model well reproduces LQCD data on screening masses $M_{\xi }^{\mathrm{scr}}(T)$ for both scalar and pseudoscalar mesons, particularly in $T\ge T_c^{\chi }$. Using this effective model, we predict meson pole masses $M_{\xi }^{\mathrm{pole}}(T)$ for scalar and pseudoscalar mesons. For ${\eta }^{\prime }$ meson, the prediction is consistent with the experimental value at finite $T$ measured in heavy-ion collisions. We point out that the relation $M_{\xi }^{\mathrm{scr}}(T)-M_{\xi }^{\mathrm{pole}}(T)\approx M_{{\xi }^{\prime }}^{\mathrm{scr}}(T)-M_{{\xi }^{\prime }}^{\mathrm{pole}}(T)$ is pretty good when $\xi$ and ${\xi }^{\prime }$ are scalar mesons, and show that the relation $M_{\xi }^{\mathrm{scr}}(T)/M_{{\xi }^{\prime }}^{\mathrm{scr}}(T)\approx M_{\xi }^{\mathrm{pole}}(T)/M_{{\xi }^{\prime }}^{\mathrm{pole}}(T)$ is well satisfied within 20% error when $\xi$ and ${\xi }^{\prime }$ are pseudoscalar mesons and also when $\xi$ and ${\xi }^{\prime }$ are scalar mesons.

   hep-phhep-exhep-latnucl-thPRD(2017)·28 citations
6. 06*

   Higgs boson couplings in multi-doublet models with natural flavour conservation

   Kei Yagyu🇬🇧

   We investigate the deviation in the couplings of the standard model (SM) like Higgs boson ($h$) with a mass of 125 GeV from the prediction of the SM in multi-doublet models within the framework where flavour changing neutral currents at the tree level are naturally forbidden. After we present the general expressions for the modified gauge and Yukawa couplings for $h$, we show the correlation between the deviation in the Yukawa coupling for the tau lepton $h{\tau }^{+}{\tau }^{-}$ and that for the bottom quark $hb\bar{b}$ under the assumption of a non-zero deviation in the $hVV$ $(V=W,Z)$ couplings in two Higgs doublet models (2HDMs) and three Higgs doublet models (3HDMs) as simple examples. We clarify the possible allowed prediction of the deviations in the 3HDMs which cannot be explained in the 2HDMs even taking into account the one-loop electroweak corrections to the Yukawa coupling.

   hep-phPLB(2016)·19 citations
7. 07*

   Chiral spiral induced by a strong magnetic field

   H. Abuki🇯🇵

   We study the modification of the chiral phase structure of QCD due to an external magnetic field. We first demonstrate how the effect of magnetic field can systematically be incorporated into a generalized Ginzburg-Landau framework. We then analyze the phase structure in the vicinity of the chiral critical point. In the chiral limit, the effect is found to be so drastic that it totally washes the tricritical point out of the phase diagram, bringing the continent for the chiral spiral. This is the case no matter how small is the intensity of the magnetic field. On the other hand, the current quark mass protects the chiral critical point from a weak magnetic field. However the critical point will eventually be covered by the chiral spiral phase as the magnetic field grows.

   hep-phnucl-thEPJ Web Conf.(2016)·8 citations
8. 08*

   Quasi-two-body decays $B\to K\rho \to K\pi \pi$ in perturbative QCD approach

   Wen-Fei Wang🇨🇳 · Hsiang-nan Li🇹🇼

   We analyze the quasi-two-body decays $B\to K\rho \to K\pi \pi$ in the perturbative QCD (PQCD) approach, in which final-state interactions between the pions in the resonant regions associated with the $P$-wave states $\rho (770)$ and ${\rho }^{\prime }(1450)$ are factorized into two-pion distribution amplitudes. Adopting experimental inputs for the time-like pion form factors involved in two-pion distribution amplitudes, we calculate branching ratios and direct $CP$ asymmetries of the $B\to K\rho (770),K{\rho }^{\prime }(1450)\to K\pi \pi$ modes. It is shown that agreement of theoretical results with data can be achieved, through which Gegenbauer moments of the $P$-wave two-pion distribution amplitudes are determined. The consistency between the three-body and two-body analyses of the $B\to K\rho (770)\to K\pi \pi$ decays supports the PQCD factorization framework for exclusive hadronic $B$ meson decays.

   hep-phhep-exPLB(2016)·85 citations
9. 09*

   TAUOLA of tau lepton decays-- framework for hadronic currens, matrix elements and anomalous decays

   M. Chrzaszcz🇨🇭 · T. Przedzinski🇵🇱 · Z. Was🇵🇱 · J. Zaremba🇵🇱

   We present an update of the Monte Carlo event generator TAUOLA for tau lepton decays, with substantially increased list of decay channels and new initialization options. The core of the program remains written in FORTRAN but necessary arrangements have been made to allow handling of the user-provided hadronic currents and matrix elements at the execution time. Such solution may simplify preparation of new hadronic currents and may be useful for fitting to the experimental data as well. We have implemented as default for TAUOLA a set of hadronic currents, which is compatible with the default initialization used by BaBar collaboration. Options for currents available in previous releases are still stored in the code, sometimes left defunct or activated by internal flags only. The new version of the program, includes also implementation of Lepton Flavour Violating tau decays. Finally, we present, as an example, a set of C++ methods for handling user-provided currents, matrix elements or complete new decay channels initialization which can be performed at the program execution time.

   hep-phComput.Phys.Commun.(2018)·63 citations
10. 10*

    Strong Couplings of Three Mesons with Charm(ing) Involvement

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Hagop Sazdjian🇫🇷 · Silvano Simula🇮🇹

    We determine the strong couplings of three mesons that involve, at least, one ${\eta }_c$ or $J/\psi$ meson, within the framework of a constituent-quark model by means of relativistic dispersion formulations. For strong couplings of $J/\psi$ mesons to two charmed mesons, our approach leads to predictions roughly twice as large as those arising from QCD sum rules.

    hep-phnucl-thEPJ Web Conf.(2017)·0 citations
11. 11*

    Oscillations Beyond Three-Neutrino Mixing

    Carlo Giunti🇮🇹

    The current status of the phenomenology of short-baseline neutrino oscillations induced by light sterile neutrinos in the framework of 3+1 mixing is reviewed.

    hep-phastro-ph.COhep-exJ.Phys.Conf.Ser.(2017)·10 citations
12. 12*

    A unified composite model of inflation and dark matter in the Nambu-Jona-Lasinio theory

    Phongpichit Channuie (Walailak U.)🇹🇭 · Chi Xiong (Nanyang Technol. U.)🇸🇬

    In this work, we propose a cosmological scenario inherently based on the effective Nambu-Jona-Lasinio (NJL) model that cosmic inflation and dark matter can be successfully described by a single framework. On the one hand, the scalar channel of the NJL model plays a role of the composite inflaton (CI) and we show that it is viable to achieve successful inflation via a non-minimal coupling to gravity. For model of inflation, we compute the inflationary parameters and confront them with recent Planck 2015 data. We discover that the predictions of the model are in excellent agreement with the Planck analysis. We also present in our model a simple connection of physics from the high scales to low scales via renormalization group equations of the physical parameters. On the other hand, the pseudoscalar channel can be assigned as a candidate for composite dark matter (CD). For model of dark matter, we couple the pseudoscalar to the Higgs sector of the standard model with the coupling strength $\kappa$ and estimate its thermally-averaged relic abundance. We discover that the CD mass is strongly sensitive to the coupling $\kappa$. We find in case of light CD, $M_s<M_h/2$, that the required relic abundance is archived for value of its mass $M_s\sim 61\mathrm{GeV}$ for $\kappa =0.1$. However, in this case the CD mass can be lighter when the coupling is getting larger. Moreover, in case of heavy CD, $M_s>M_{W,Z}$ (or $>M_h$), the required relic abundance can be satisfied for value of the CD mass $M_s\sim 410\mathrm{GeV}$ for $\kappa =0.5$. In contradiction to the light mass case, however, the CD mass in this case can even be heavier when the coupling is getting larger.

    hep-phgr-qchep-thPRD(2017)·16 citations
13. 13*

    Nonthermal Gravitino Production after Large Field Inflation

    Yohei Ema🇯🇵 · Kyohei Mukaida🇯🇵 · Kazunori Nakayama🇯🇵 · Takahiro Terada🇰🇷

    We revisit the nonthermal gravitino production at the (p)reheating stage after inflation. Particular attention is paid to large field inflation models with a ${\mathbb{Z}}_2$ symmetry, for which the previous perturbative analysis is inapplicable; and inflation models with a stabilizer superfield, which have not been studied non-perturbatively. It is found that in single-superfield inflation models (without the stabilizer field), nonthermal production of the transverse gravitino can be cosmologically problematic while the abundance of the longitudinal gravitino is small enough. In multi-superfield inflation models (with the stabilizer field), production of the transverse and longitudinal gravitinos is significantly suppressed, and they are cosmologically harmless. We also clarify the relation between the background field method used in the preheating context and the standard perturbative decay method to estimate the gravitino abundance.

    hep-phastro-ph.COhep-thJHEP(2016)·31 citations
14. 14*

    Influence of solar flares on behavior of solar neutrino flux

    O.M.Boyarkin🇧🇾 · G.G.Boyarkina🇧🇾

    Limiting ourselves to two flavor approximation the motion of the neutrino flux in the solar matter and twisting magnetic field is considered. For the neutrino system described by the 4-component wave function ${\Psi }^T=({\nu }_{eL},{\nu }_{XL},{\overline{\nu }}_{eR},{\overline{\nu }}_{XL})$, where $X=\mu ,\tau$, an evolution equation is found. Our consideration carries general character, that is, it holds for any SM extensions with massive neutrinos. The resonance transitions of the electron neutrinos are investigated. Factors which influence on the electron neutrino flux, crossing a region of solar flares (SF) are defined. When the SF is absent a terrestrial detector records the electron neutrino flux weakened at the cost both of vacuum oscillations and of the MSW resonance conversion only. On the other hand, the electron neutrino flux passed the SF region in preflare period proves to be further weakened in so far as it undergoes one (Majorana neutrino) or two (Dirac neutrino) additional resonance conversions, apart from the MSW resonance and vacuum oscillations. The hypothesis of the ${\nu }_e$-induced decays which states that decreasing the beta decay rates of some elements of the periodic table is caused by reduction of the solar neutrino flux is discussed as well. PACS number(s): 12.60.Cn, 14.60.Pg, 96.60.Kx, 95.85.Qx, 96.60.Rd.

    hep-phAstropart.Phys.(2016)·6 citations
15. 15*

    Soft-Collinear Supersymmetry

    Timothy Cohen🇺🇸 · Gilly Elor🇺🇸 · Andrew J. Larkoski🇺🇸

    Soft-Collinear Effective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. This paper demonstrates that SCET can be made compatible with supersymmetry (SUSY). Explicitly, the effective Lagrangian for $\mathcal{N}=1$ SUSY Yang-Mills is constructed and shown to be a complete description for the infrared of this model. For contrast, we also construct the effective Lagrangian for chiral SUSY theories with Yukawa couplings, specifically the single flavor Wess-Zumino model. Only a subset of the infrared divergences are reproduced by the Lagrangian -- to account for the complete low energy description requires the inclusion of local operators. SCET is formulated by expanding fields along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light-cone. Defining the theory with respect to a specific frame obfuscates Lorentz invariance -- given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang-Mills in "collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of superfields. As a byproduct, bootstrapping up to the full theory yields the first algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. This work paves the way toward discovering the effective theory for the collinear limit of $\mathcal{N}=4$ SUSY Yang-Mills.

    ↳ hep-thhep-phJHEP(2017)·8 citations
16. 16*

    Meson Spectroscopy at COMPASS

    Boris Grube (for the COMPASS collaboration)🇩🇪

    The goal of the COMPASS experiment at CERN is to study the structure and dynamics of hadrons. The two-stage spectrometer used by the experiment has large acceptance and covers a wide kinematic range for charged as well as neutral particles and can therefore measure a wide range of reactions. The spectroscopy of light mesons is performed with negative (mostly ${\pi }^{-}$) and positive ($p$, ${\pi }^{+}$) hadron beams with a momentum of 190 GeV/$c$. The light-meson spectrum is measured in different final states produced in diffractive dissociation reactions with squared four-momentum transfer $t$ to the target between 0.1 and 1.0 $(\text{GeV}/c{)}^2$. The flagship channel is the ${\pi }^{-}{\pi }^{-}{\pi }^{+}$ final state, for which COMPASS has recorded the currently world's largest data sample. These data not only allow to measure the properties of known resonances with high precision, but also to observe new states. Among these is a new axial-vector signal, the $a_1(1420)$, with unusual properties. Novel analysis techniques have been developed to extract also the amplitude of the ${\pi }^{-}{\pi }^{+}$ subsystem as a function of $3\pi$ mass from the data. The findings are confirmed by the analysis of the ${\pi }^{-}{\pi }^0{\pi }^0$ final state.

    ↳ hep-exhep-phEPJ Web Conf.(2016)·0 citations
17. 17*

    Supersymmetry in 6d Dirac Action

    Yukihiro Fujimoto🇯🇵 · Kouhei Hasegawa🇯🇵 · Kenji Nishiwaki🇰🇷 · Makoto Sakamoto🇯🇵 · Kentaro Tatsumi🇯🇵

    We investigate a 6d Dirac fermion on a rectangle. It is found that the 4d spectrum is governed by $N=2$ supersymmetric quantum mechanics. Then we demonstrate that the supersymmetry is very useful for classifying all the allowed boundary conditions and to expand the 6d Dirac field in Kaluza-Klein modes. A striking feature of the model is that even though the 6d Dirac fermion has non-vanishing bulk mass, the 4d mass spectrum can contain degenerate massless chiral fermions, which may provide a hint to solve the problem of the generation of quarks and leptons. It is pointed out that zero-energy solutions are not affected by the presence of the boundaries, while the boundary conditions work well for determining the positive-energy solutions. We also provide a brief discussion on possible boundary conditions in the general case, especially those on polygons.

    ↳ hep-thhep-phPTEP(2017)·9 citations
18. 18*

    MESON2016 -- Concluding Remarks

    Avraham Gal🇮🇱

    Several topics presented and discussed at MESON2016 are highlighted, including pentaquarks, dibaryons and meson-nuclear bound states.

    ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2016)·10 citations
19. 19*

    Anomalous spectral lines and relic quantum nonequilibrium

    Nicolas G. Underwood🇺🇸 · Antony Valentini🇺🇸

    We describe features that could be observed in the line spectra of relic cosmological particles should quantum nonequilibrium be preserved in their statistics. According to our arguments, these features would represent a significant departure from those of a conventional origin. Among other features, we find a possible spectral broadening that is proportional to the energy resolution of the recording telescope (and so could be much larger than any conventional broadening). Notably, for a range of possible initial conditions we find the possibility of spectral line "narrowing", whereby a telescope could observe a line that is narrower than it is conventionally able to resolve. We discuss implications for the indirect search for dark matter, with particular reference to some recent controversial spectral lines.

    ↳ quant-phastro-ph.COhep-phPRD(2020)·17 citations
20. 20*

    Direct Search for keV Sterile Neutrino Dark Matter with a Stable Dysprosium Target

    T. Lasserre🇫🇷 · K. Altenmueller🇫🇷 · M. Cribier🇫🇷 · A. Merle🇩🇪 · S. Mertens🇩🇪 · M. Vivier🇫🇷

    We investigate a new method to search for keV-scale sterile neutrinos that could account for Dark Matter. Neutrinos trapped in our galaxy could be captured on stable ${}^{163}$Dy if their mass is greater than 2.83 keV. Two experimental realizations are studied, an integral counting of ${}^{163}$Ho atoms in dysprosium-rich ores and a real-time measurement of the emerging electron spectrum in a dysprosium-based detector. The capture rates are compared to the solar neutrino and radioactive backgrounds. An integral counting experiment using several kilograms of ${}^{163}$Dy could reach a sensitivity for the sterile-to-active mixing angle ${\sin }^2{\theta }_{e4}$ of $10^{-5}$ significantly exceeding current laboratory limits. Mixing angles as low as ${\sin }^2{\theta }_{e4}\sim 10^{-7}$ / ${\mathrm{m}}_{{}^{163}\mathrm{Dy}}(\mathrm{ton})$ could possibly be explored with a real-time experiment.

    ↳ hep-exastro-ph.COhep-ph13 citations
21. 21*

    Shortcomings of New Parametrizations of Inflation

    Jerome Martin🇫🇷 · Christophe Ringeval🇧🇪 · Vincent Vennin🇬🇧

    In the hope of avoiding model dependence of the cosmological observables, phenomenological parametrizations of Cosmic Inflation have recently been proposed. Typically, they are expressed in terms of two parameters associated with an expansion of the inflationary quantities matching the belief that inflation is characterized by two numbers only, the tensor-to-scalar ratio and the scalar spectral index. We give different arguments and examples showing that these new approaches are either not generic or insufficient to make predictions at the accuracy level needed by the cosmological data. We conclude that disconnecting inflation from high energy physics and gravity might not be the most promising way to learn about the physics of the early Universe.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2016)·33 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.