Thu·Oct 6, 2016Thursday·October 6, 2016

1. 01*

   Transverse Force on Transversely Polarized Quarks in Longitudinally Polarized Nucleons

   Manal Abdallah🇺🇸 · Matthias Burkardt🇺🇸

   We study the semi-classical interpretation of the $x^3$ and $x^4$ moments of twist-3 parton distribution functions (PDFs). While no semi-classical interpretation for the higher moments of $g_T(x)$ and $e(x)$ was find, the $x^3$ moment of the chirally odd spin-dependent twist-3 PDF $h_L^3(x)$ can be related to the longitudinal gradient of the transverse force on transversely polarized quarks in longitudinally polarized nucleons in a DIS experiment. We discuss how this result relates to the torque acting on a quark in the same experiment. This has further implications for comparisons between tha Jaffe-Manohar and the Ji decompositions of the nucleon spin.

   hep-phPRD(2016)·7 citations
2. 02*

   Anomaly-driven inverse cascade and inhomogeneities in a magnetized chiral plasma in the early Universe

   E. V. Gorbar🇺🇦 · I. Rudenok🇺🇦 · I. A. Shovkovy🇺🇸 · S. Vilchinskii🇺🇦

   By making use of a simple model that captures the key features of the anomalous Maxwell equations, we study the role of inhomogeneities on the evolution of magnetic fields in a chiral plasma. We find that inhomogeneities of the chiral asymmetry by themselves do not prevent the anomaly-driven inverse cascade and, as in the homogeneous case, the magnetic helicity is transferred from shorter to longer wavelength helical modes of the magnetic field. However, we also find that the evolution appears to be sensitive to the effects of diffusion. In the case when diffusion is negligible, the inverse cascade slows down considerably compared to the homogeneous scenario. In the case of the primordial plasma, though, we find that the diffusion is substantial and efficiently suppresses chiral asymmetry inhomogeneities. As a result, the inverse cascade proceeds practically in the same way as in the chirally homogeneous model.

   hep-phastro-ph.COPRD(2016)·31 citations
3. 03*

   Lepton flavor violation in the Simplest Little Higgs model

   P. Roig🇲🇽

   Little Higgs Models are a possible elegant solution to the hierarchy problem on the Higgs mass. As they predict naturally small deviations with respect to SM results, they are in agreement with all current experimental data. In this contribution, we review lepton flavor violation in the Simplest Little Higgs model focusing on semileptonic lepton flavor violating tau decays (where some new results are presented) and $H\to \ell {\ell }^{\prime }$. Within this model, the most promising decay channels for discovering lepton flavor violation are $\mu \to e$ conversion in nuclei, $\mu \to e{\gamma }^{(\ast )}$, $\tau \to (e/\mu )\gamma$ and $\tau \to (e/\mu )({\pi }^{+}{\pi }^{-}/\rho )$.

   hep-phhep-exNucl.Part.Phys.Proc.(2017)·1 citation
4. 04*

   On a realization of $\{\beta \}$-expansion in QCD

   S. V. Mikhailov🇷🇺

   We suggest a simple algebraic approach to fix the elements of the $\{\beta \}$-expansion for renormalization group invariant quantities, which uses additional degrees of freedom. The approach is discussed in detail for N${}^2$LO calculations in QCD with the MSSM gluino -- an additional degree of freedom. We derive the formulae of the $\{\beta \}$-expansion for the nonsinglet Adler $D$-function and Bjorken polarized sum rules in the actual N${}^3$LO within this quantum field theory scheme with the MSSM gluino and the scheme with the second additional degree of freedom. We discuss the properties of the $\{\beta \}$-expansion for higher orders considering the N${}^4$LO as an example.

   hep-phJHEP(2017)·6 citations
5. 05*

   The High Energy Radiation Pattern from BFKLex

   G. Chachamis🇪🇸 · A. Sabio Vera🇪🇸

   We discuss a recent study on high-energy jet production in the multi-Regge limit done with the use of the Monte Carlo event generator BFKLex which includes collinear improvements in the form of double-log contributions. We will show results for the average transverse momentum and azimuthal angle of the final state jets when at least one of them is very forward in rapidity and another one is very backward. We also discuss the introduction of a new observable which accounts for the average rapidity ratio among subsequent emissions.

   hep-ph1 citation
6. 06*

   Inclusive three jet production at the LHC at 7 and 13 TeV collision energies

   G. Chachamis🇪🇸 · F. Caporale🇪🇸 · F. G. Celiberto🇮🇹 · D. Gordo Gomez🇪🇸 · A. Sabio Vera🇪🇸

   We discuss briefly a recent study of new observables in LHC inclusive events with three tagged jets. One jet is in the forward direction, the second is in the backward direction and well-separated in rapidity from the first, whereas, the third tagged jet is to be found in more central regions of the detector. Taking into consideration that non-tagged mini-jet emissions are allowed and that they may be accounted for by the BFKL gluon Green function, we project the cross sections on azimuthal-angle components and define suitable ratios based on these projections which can provide several distinct tests of the BFKL dynamics.

   hep-ph16 citations
7. 07*

   Discriminating between Thermal and Nonthermal Cosmic Relic Neutrinos through Annual Modulation at PTOLEMY

   Guo-yuan Huang🇨🇳 · Shun Zhou🇨🇳

   If massive neutrinos are Dirac particles, the proposed PTOLEMY experiment will hopefully be able to discover cosmic neutrino background via ${\nu }_e^{}+{}^3\mathrm{H}\to {}^3\mathrm{He}+e^{-}$ with a capture rate of ${\Gamma }_{\mathrm{D}}^{}\approx 4{\mathrm{yr}}^{-1}$. Recently, it has been pointed out that right-handed components of Dirac neutrinos could also be copiously produced in the early Universe and become an extra thermal or nonthermal ingredient of cosmic relic neutrinos, enhancing the capture rate to ${\Gamma }_{\mathrm{D}}^{}\approx 5.1{\mathrm{yr}}^{-1}$ or ${\Gamma }_{\mathrm{D}}^{}\approx 6.1{\mathrm{yr}}^{-1}$. In this work, we investigate the possibility to distinguish between thermal and nonthermal spectra of cosmic relic neutrinos by measuring the annual modulation of the capture rate. For neutrino masses of $0.1\mathrm{eV}$, we have found the amplitude of annual modulation in the standard case is $\mathcal{M}\approx 0.05\%$, which will be increased to $0.1\%$ and $0.15\%$ in the presence of additional thermal and nonthermal right-handed neutrinos, respectively. The future detection of such a modulation will be helpful in understanding the Majorana or Dirac nature of massive neutrinos.

   hep-phastro-ph.COPRD(2016)·21 citations
8. 08*

   On the $h\to V{\ell }^{+}{\ell }^{-}$ decays

   Pietro Santorelli🇮🇹

   A set of exclusive decays of the Higgs boson into a vector meson and a dilepton pair ($h\to V{\ell }^{+}{\ell }^{-}$, with $V={\rm Y},J/\psi ,\varphi$, and $\ell =\mu ,\tau$) are studied in the framework of the Standard Model. We have evaluated the decay rates, the dilepton mass spectra and the $V$ longitudinal helicity fraction distributions. In the same framework, we considered the exclusive modes $h\to V\nu \bar{\nu }$ and the implications of the CMS and ATLAS results for the lepton flavor-changing process $h\to {\tau }^{+}{\mu }^{-}$ on the $h\to V{\tau }^{+}{\mu }^{-}$ decay modes.

   hep-phEPJ Web Conf.(2016)·2 citations
9. 09*

   Theoretical studies of the reaction e+ e- --> K+ K- gamma

   Leonard Lesniak🇵🇱 · Michal Silarski🇮🇹

   We present studies of the e+ e- --> K+ K- gamma reaction for the e+e- center-of-mass energies close to the phi(1020) meson mass. Different mechanisms leading to the final state are considered. The strong interaction amplitudes of the K+K- pairs in the S-wave are taken into account. In addition, the photon emission in the initial state, the final state radiation effects and all the possible interference terms are included in the transition matrix elements. The K+K- effective mass distributions and the angular dependence of the reaction cross-section are calculated.

   hep-phhep-exEPJ Web Conf.(2016)·1 citation
10. 10*

    Operators for scattering of particles with spin

    S. Prelovsek🇸🇮 · U. Skerbis🇸🇮 · C.B. Lang🇦🇹

    Operators for simulating the scattering of two particles with spin are constructed. Three methods are shown to give the consistent lattice operators for PN, PV, VN and NN scattering, where P, V and N denote pseudoscalar meson, vector meson and nucleon. The projection method leads to one or several operators $O_{\Gamma ,r,n}$ that transform according to a given irreducible representation $\Gamma$ and row r. However, it gives little guidance on which continuum quantum numbers of total J, spin S, orbital momentum L or single-particle helicities ${\lambda }_{1,2}$ will be related with a given operator. This is remedied with the helicity and partial-wave methods. There first the operators with good continuum quantum numbers $(J,P,{\lambda }_{1,2})$ or $(J,L,S)$ are constructed and then subduced to the irreps $\Gamma$ of the discrete lattice group. The results indicate which linear combinations $O_{\Gamma ,r,n}$ of various n have to be employed in the simulations in order to enhance couplings to the states with desired continuum quantum numbers. The total momentum of two hadrons is restricted to zero since parity P is a good quantum number in this case.

    ↳ hep-lathep-phPoS(2016)·0 citations
11. 11*

    Linde problem in Yang-Mills theory compactified on ${\mathbb{R}}^2\times {\mathbb{T}}^2$

    Eduardo S. Fraga (Rio de Janeiro Federal U.)🇧🇷 · Daniel Kroff (Sao Paulo, IFT)🇧🇷 · Jorge Noronha (Sao Paulo U.)🇧🇷

    We investigate the perturbative expansion in $SU(3)$ Yang-Mills theory compactified on ${\mathbb{R}}^2\times {\mathbb{T}}^2$ where the compact space is a torus ${\mathbb{T}}^2=S_{\beta }^1\times S_L^1$, with $S_{\beta }^1$ being a thermal circle with period $\beta =1/T$ ($T$ is the temperature) while $S_L^1$ is a circle with finite length $L=1/M$, where $M$ is an energy scale. A Linde-type analysis indicates that perturbative calculations for the pressure in this theory break down already at order $\mathcal{O}(g^2)$ due to the presence of a non-perturbative scale $\sim g\sqrt{TM}$. We conjecture that a similar result should hold if the torus is replaced by any other compact surface of genus one.

    ↳ hep-thhep-lathep-phPRD(2017)·5 citations
12. 12*

    Generation of circular polarization of gamma ray bursts

    S. Batebi🇮🇷 · R. Mohammadi🇮🇷 · R. Ruffini🇮🇹 · S. Tizchang🇮🇷 · S.S. Xue🇮🇹

    The generation of the circular polarization of Gamma Ray Burst (GRB) photons is discussed in this paper via their interactions with astroparticles in the presence or absence of background fields such as magnetic fields and non-commutative space time geometry. Solving quantum Boltzmann equation for GRB-photons as a photon ensemble, we discuss the generation of circular polarization (as Faraday conversion phase shift $\Delta {\varphi }_{FC}$) of GRBs in the following cases: (i) intermediate interactions, i.e. the Compton scattering of GRBs in the galaxy cluster magnetic field and in the presence of non-commutative space time geometry, as well as the scattering of GRBs in cosmic neutrino background (CNB), and in cosmic microwave background (CMB); (ii) interactions with particles and fields in shock wave, i.e. the Compton scattering of GRBs with accelerated charged particles in the presence of magnetic fields. We found that (i) after shock wave crossing, the most contribution of $\Delta {\varphi }_{FC}$ for energetic GRBs (in order GeV and larger) comes from GRB-CMB interactions, however for low energy GRBs the contributions of the Compton scattering of GRBs in the galaxy cluster magnetic field dominate; (ii) in shock wave crossing, the magnetic filed has significant effects on converting GRB's linear polarization to circular one, this effect can be used to better understanding magnetic profile in shock wave. The main aim of this work is a emphasis that the studying and measuring the circular polarization of GRBs are helpful for better understanding of physics and mechanism of the generation of GRBs and their interactions before reaching us.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2016)·8 citations
13. 13*

    The spectrum of light isovector mesons with $C=+1$ from the COMPASS experiment

    Stephan Paul🇩🇪

    Based on the largest event sample of diffractively produced ${\pi }^{-}{\pi }^{-}{\pi }^{+}$, obtained by a pion beam of $190GeV/c$ momentum, the COMPASS collaboration has performed the most advanced partial wave analysis on multi-body final states, using the isobar model. The large number of waves included in the analysis reduces truncation effects. We have used fourteen out of a total of eighty-eight waves, to extract resonance parameters for eleven light meson candidates, most of them observed previously. The coherence of the analysis and the large variety of systematic studies has allowed to determine mass and width of most $a_J$ and ${\pi }_J$ states with six different values of $J^{PC}$ below a mass of $2.1GeV/{\mathrm{c}}^2$, with high confidence. We exploited that the production rates of resonant and non-resonant contributions in these fourteen waves vary differently with the four-momentum transfer squared in the reaction. In addition, we have performed the first isobar-freed analysis in diffraction, from which we have determined the shape of the $[\pi \pi {]}_{S-wave}$ isobar for different $J^{PC}$ of the $3\pi$ system.

    ↳ hep-exhep-phJPS Conf.Proc.(2017)·0 citations
14. 14*

    Light sterile neutrinos and pseudoscalar interactions in cosmology

    Stefano Gariazzo🇮🇹

    The Short BaseLine (SBL) neutrino oscillations anomalies hint at the presence of a sterile neutrino with a mass of around 1 eV. However, such neutrino is highly incompatible with the cosmological data, in particular from the Cosmic Microwave Background (CMB), if no new physics is assumed. An interesting possibility for reconciling the 1 eV sterile neutrino presence in cosmology is related to the existence of a new pseudoscalar interaction. If the sterile neutrinos experience such a pseudoscalar interaction, the cosmological analyses of the full CMB data prefer a sterile neutrino mass that is fully compatible with the SBL determinations. The additional interaction allows to obtain also an improved compatibility of the cosmological predictions with the local measurements of the Hubble parameter.

    ↳ astro-ph.COhep-phPoS(2017)·1 citation
15. 15*

    Time evolution of linearized gauge field fluctuations on a real-time lattice

    Aleksi Kurkela🇨🇭 · Tuomas Lappi🇫🇮 · Jarkko Peuron🇫🇮

    Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Due to instabilities, small quantum fluctuations on top of the classical background may significantly affect the dynamics of the system. In this paper we argue for the need for a numerical calculation of a system of classical gauge fields and small linearized fluctuations in a way that keeps the separation between the two manifest. We derive and test an explicit algorithm to solve these equations on the lattice, maintaining gauge invariance and Gauss's law.

    ↳ hep-lathep-phnucl-thEPJC(2016)·24 citations
16. 16*

    Cosmological implications of Higgs field fluctuations during inflation

    A.V. Grobov🇷🇺 · R.V. Konoplich🇺🇸 · S.G. Rubin🇷🇺

    Cosmological implications of Higgs field fluctuations during inflation are considered. This study is based on the Standard Model and the standard quadratic model of chaotic inflation where the Higgs field is minimally coupled to gravity and has no direct coupling to the inflaton. In the Standard model the renormalisation group improved effective potential develops an instability (an additional minimum and maximum) at large field values. It is shown that such a new maximum should take place at an energy scale above $10^{14}\text{GeV},$ otherwise a universe like ours is extremely unlikely. The extension to the case of the Higgs field interacting with the inflaton field is discussed.

    ↳ astro-ph.COhep-phAnnalen Phys.(2016)·6 citations
17. 17*

    Pion-nucleon scattering in the Roper channel from lattice QCD

    C. B. Lang🇦🇹 · L. Leskovec🇺🇸 · M. Padmanath🇩🇪 · S. Prelovsek🇸🇮

    We present a lattice QCD study of $N\pi$ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance $N^{\ast }(1440)$ resides in experiment. The study is based on the PACS-CS ensemble of gauge configurations with $N_f=2+1$ Wilson-clover dynamical fermions, $m_{\pi }\simeq 156$MeV and $L\simeq 2.9$fm. In addition to a number of $qqq$ interpolating fields, we implement operators for $N\pi$ in $p$-wave and $N\sigma$ in $s$-wave. In the center-of-momentum frame we find three eigenstates below 1.65 GeV. They are dominated by $N(0)$, $N(0)\pi (0)\pi (0)$ (mixed with $N(0)\sigma (0)$) and $N(p)\pi (-p)$ with $p\simeq 2\pi /L$, where momenta are given in parentheses. This is the first simulation where the expected multi-hadron states are found in this channel. The experimental $N\pi$ phase-shift would -- in the approximation of purely elastic $N\pi$ scattering -- imply an additional eigenstate near the Roper mass $m_R\simeq 1.43$GeV for our lattice size. We do not observe any such additional eigenstate, which indicates that $N\pi$ elastic scattering alone does not render a low-lying Roper. Coupling with other channels, most notably with $N\pi \pi$, seems to be important for generating the Roper resonance, reinforcing the notion that this state could be a dynamically generated resonance. Our results are in line with most of previous lattice studies based just on $qqq$ interpolators, that did not find a Roper eigenstate below $1.65$GeV. The study of the coupled-channel scattering including a three-particle decay $N\pi \pi$ remains a challenge.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2017)·128 citations
18. 18*

    Non-supersymmetric AdS and the Swampland

    Hirosi Ooguri🇺🇸 · Cumrun Vafa🇺🇸

    We propose to sharpen the weak gravity conjecture by the statement that, except for BPS states in a supersymmetric theory, the gravitational force is strictly weaker than any electric force and provide a number of evidences for this statement. Our conjecture implies that any non-supersymmetric anti-de Sitter vacuum supported by fluxes must be unstable, as is the case for all known attempts at such holographic constructions.

    ↳ hep-thhep-phAdv.Theor.Math.Phys.(2017)·464 citations
19. 19*

    Inverse Magnetic Catalysis in the Soft-Wall Model of AdS/QCD

    Danning Li🇨🇳 · Mei Huang🇨🇳 · Yi Yang🇹🇼 · Pei-Hung Yuan🇹🇼

    Magnetic effects on chiral phase transition have been investigated in a modified soft-wall AdS/QCD model, in which the dilaton field is taken to be negative at the ultraviolet region and positive at the infrared region as in Phys.Rev.D93(2016),101901 and JHEP1604(2016)036. The magnetic field is introduced into the background geometry by solving the Einstein-Maxwell system. After embedding the magnetized background geometry into the modified soft-wall model, the magnetic field dependent behavior of chiral condensate is worked out numerically. It is found that, in the chiral limit, the chiral phase transition remains as a second order at finite magnetic field $B$, while the symmetry restoration temperature and chiral condensate decrease with the increasing of magnetic field in small $B$ region. When including finite quark mass effect, the phase transition turns to be a crossover one, and the transition temperature still decreases with increasing magnetic field $B$ when $B$ is not very large. In this sense, inverse magnetic catalysis effect is observed in this modified soft-wall AdS/QCD model.

    ↳ hep-thhep-phJHEP(2017)·74 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.