Thu·Mar 24, 2016Thursday·March 24, 2016

1. 01*

   CP-odd invariants for multi-Higgs models: applications with discrete symmetry

   Ivo de Medeiros Varzielas🇬🇧 · Stephen F. King🇬🇧 · Christoph Luhn🇩🇪 · Thomas Neder🇬🇧

   CP-odd invariants provide a basis independent way of studying the CP properties of Lagrangians. We propose powerful methods for constructing basis invariants and determining whether they are CP-odd or CP-even, then systematically construct all of the simplest CP-odd invariants up to a given order, finding many new ones. The CP-odd invariants are valid for general potentials when expressed in a standard form. We then apply our results to scalar potentials involving three (or six) Higgs fields which form irreducible triplets under a discrete symmetry, including invariants for both explicit as well as spontaneous CP violation. The considered cases include one triplet of Standard Model (SM) gauge singlet scalars, one triplet of SM Higgs doublets, two triplets of SM singlets, and two triplets of SM Higgs doublets. For each case we study the potential symmetric under one of the simplest discrete symmetries with irreducible triplet representations, namely $A_4$, $S_4$, $\Delta (27)$ or $\Delta (54)$, as well as the infinite classes of discrete symmetries $\Delta (3n^2)$ or $\Delta (6n^2)$.

   hep-phPRD(2016)·32 citations
2. 02*

   Vacuum birefringence in high-energy laser-electron collisions

   B. King🇬🇧 · N. Elkina🇩🇪

   Real photon-photon scattering is a long-predicted phenomenon that is being searched for in experiment in the form of a birefringent vacuum at optical and X-ray frequencies. We present results of calculations and numerical simulations for a scenario to measure this effect using multi-MeV photons generated in the collision of electrons with a laser pulse. We find that the birefringence of the vacuum should be measurable using experimental parameters attainable in the near future.

   hep-phPRA(2016)·74 citations
3. 03*

   Hunting the Flavon

   Martin Bauer🇩🇪 · Torben Schell🇩🇪 · Tilman Plehn🇩🇪

   The next generation of experiments in particle physics will for the first time systematically test flavor physics models based on flavon fields. Starting from the current quark-flavor constrains on such models we show how the new generation of lepton flavor experiments will dominate indirect searches in the coming decades. A future 100 TeV hadron collider will then be the first experiment to probe flavons as propagating degrees of freedom. Our estimate of the collider reach relies on a proper treatment of backgrounds and detector effects. Complementary searches for indirect effects in lepton flavor experiments and propagating degrees of freedom at colliders are very limited at the LHC, but will be a new feature at a 100 TeV hadron collider.

   hep-phPRD(2016)·80 citations
4. 04*

   Diphoton Resonance in F-theory inspired Flipped SO(10)

   George K. Leontaris🇬🇷 · Qaisar Shafi🇺🇸

   Motivated by the diphoton excess at 750 GeV reported by the ATLAS and CMS experiments, we present an F-theory inspired flipped $SO(10)$ model embedded in an $E_6$ GUT. The low energy spectrum includes the three MSSM chiral families, vectorlike color triplets, several pairs of charged $SU(2{)}_L$ singlet fields $(E^c,{\bar{E}}^c)$, as well as MSSM singlets, one or more of which can contribute to the resonance. Total decay width in the multi-GeV range can arise from couplings involving the singlet and MSSM fields

   hep-phhep-thEPJC(2016)·16 citations
5. 05*

   Di-photon portal to warped gravity

   Adam Falkowski🇫🇷 · Jernej F. Kamenik🇸🇮

   The diphoton excess around 750 GeV observed by ATLAS and CMS can be interpreted as coming from a massive spin-2 excitation. We explore this possibility in the context of warped five-dimensional models with the Standard Model (SM) fields propagating in the bulk of the extra dimension. The 750 GeV resonance is identified with the first Kaluza-Klein (KK) excitation of the five-dimensional graviton that is parametrically lighter than KK resonances of SM fields. Our set-up makes it possible to realize non-universal couplings of the spin-2 resonance to matter, and thus to explain non-observation of the 750 GeV resonance in leptonic channels. Phenomenological predictions of the model depend on the localization of fields in the extra dimension. If, as required by naturalness arguments, the zero modes of the Higgs and top fields are localized near the IR brane, one expects large branching fractions to ttbar, hh, WW, and ZZ final states. Decays to a Z boson and a photon can also be observable when the KK graviton couplings to the SM gauge fields are non-universal.

   hep-phPRD(2016)·48 citations
6. 06*

   Analytic and Monte Carlo Studies of Jets with Heavy Mesons and Quarkonia

   Reggie Bain🇺🇸 · Lin Dai🇺🇸 · Andrew Hornig🇺🇸 · Adam K. Leibovich🇺🇸 · Yiannis Makris🇺🇸 · Thomas Mehen🇺🇸

   We study jets with identified hadrons in which a family of jet-shape variables called angularities are measured, extending the concept of fragmenting jet functions (FJFs) to these observables. FJFs determine the fraction of energy, z, carried by an identified hadron in a jet with angularity, \tau_a. The FJFs are convolutions of fragmentation functions (FFs), evolved to the jet energy scale, with perturbatively calculable matching coefficients. Renormalization group equations are used to provide resummed calculations with next-to-leading logarithm prime (NLL') accuracy. We apply this formalism to two-jet events in e^+ e^- collisions with B mesons in the jets, and three-jet events in which a J/\psi is produced in the gluon jet. In the case of B mesons, we use a phenomenological FF extracted from e^+ e^- collisions at the Z^0 pole evaluated at the scale \mu = m_b. For events with J/\psi, the FF can be evaluated in terms of Non-Relativistic QCD (NRQCD) matrix elements at the scale \mu =2 m_c. The z and \tau_a distributions from our NLL' calculations are compared with predictions from monte carlo event generators. While we find consistency between the predictions for B mesons and the J/\psi distributions in \tau_a, we find the z distributions for J/\psi differ significantly. We describe an attempt to merge PYTHIA showers with NRQCD FFs that gives good agreement with NLL' calculations of the z distributions.

   hep-phJHEP(2016)·51 citations
7. 07*

   Molecular components in P-wave charmed-strange mesons

   Pablo G. Ortega🇨🇭 · Jorge Segovia🇩🇪 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸

   Results obtained by various experiments show that the $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ mesons are very narrow states located below the $DK$ and $D^{\ast }K$ thresholds, respectively. This is markedly in contrast with the expectations of naive quark models and heavy quark symmetry. Motivated by a recent lattice study which addresses the mass shifts of the $c\bar{s}$ ground states with quantum numbers $J^P=0^{+}$ ($D_{s0}^{\ast }(2317)$) and $J^P=1^{+}$ ($D_{s1}(2460)$) due to their coupling with $S$-wave $D^{(\ast )}K$ thresholds, we perform a similar analysis within a nonrelativistic constituent quark model in which quark-antiquark and meson-meson degrees of freedom are incorporated. The quark model has been applied to a wide range of hadronic observables and thus the model parameters are completely constrained. The coupling between quark-antiquark and meson-meson Fock components is done using a ${}^3{P}_0$ model in which its only free parameter $\gamma$ has been elucidated performing a global fit to the decay widths of mesons that belong to different quark sectors, from light to heavy. We observe that the coupling of the $0^{+}$ $(1^{+})$ meson sector to the $DK$ $(D^{\ast }K)$ threshold is the key feature to simultaneously lower the masses of the corresponding $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ states predicted by the naive quark model and describe the $D_{s1}(2536)$ meson as the $1^{+}$ state of the $j_q^P=3/2^{+}$ doublet predicted by heavy quark symmetry, reproducing its strong decay properties. Our calculation allows to introduce the coupling with the $D$-wave $D^{\ast }K$ channel and the computation of the probabilities associated with the different Fock components of the physical state.

   hep-phhep-exhep-latnucl-thPRD(2016)·100 citations
8. 08*

   Gauge Interactions and a Quantum Avatar in a Model with Light Cone Reflection Symmetry

   Alan Chodos🇺🇸

   We continue the development of a model of neutrinos that possesses a new symmetry, Light Cone Reflection, interchanging spacelike and timelike intervals. In this paper we introduce gauge interactions in which only the physical modes of the theory participate. We also find an avatar of the theory, involving spinors in two-dimensions that obey equations reproducing the spectrum of the original, four-dimensional theory, and we discuss the quantization of the avatar.

   hep-phhep-th3 citations
9. 09*

   Possible interrelations among chemical freezeout conditions

   A. Tawfik (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬 · M. Y. El-Bakry🇪🇬 · D. M. Habashy🇪🇬 · M. T. Mohamed (Ain Shams U., Cairo)🇪🇬 · E. Abbas (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬

   At thermal equilibrium, different chemical freezeout conditions have been proposed so far. They have an ultimate aim of proposing a universal description for the chemical freezeout parameters ($T_{ch}$ and ${\mu }_b$), which are to be extracted from the statistical fitting of different particle ratios measured at various collision energies with calculations from thermal models. A systematic comparison between these conditions is presented. The physical meaning of each of them and their sensitivity to the hadron mass cuts are discussed. Based on availability, some of them are compared with recent lattice calculations. We found that most of these conditions are thermodynamically equivalent, especially at small baryon chemical potential. We propose that further crucial consistency tests should be performed at low energies. The fireball thermodynamics is another way of guessing conditions describing the chemical freezeout parameters extracted from high-energy experiments. We endorse the possibility that the various chemical freezeout conditions should be interpreted as different aspects of one universal condition.

   hep-phnucl-thIJMPE(2016)·16 citations
10. 10*

    The Higgs Mechanism from an extra dimension

    Yu. A. Simonov (State Research Center Institute of Theoretical and Experimental Physics)

    The standard $SU(2)\times U(1)$ fields are considered in 4D plus one extra compact dimension. As a result two basic effects are obtained. First, four Goldstone-like scalars are produced, three of them are used to create longitudinal modes of the $W,Z$ fields, while the fourth becomes the Higgs-like scalar. Second, $W$ and $Z$ get their masses from the extra compact dimension with the standard pattern of symmetry violation. The resulting theory has the same fields as in the standard model, but without the Higgs vacuum average. The properties of the new Higgs scalar and its interaction with fermions are briefly discussed.

    hep-ph0 citations
11. 11*

    Generalized upper bound for inelastic diffraction

    S. M. Troshin🇷🇺 · N. E. Tyurin🇷🇺

    For the inelastic diffraction, we obtain an upper bound valid in the whole range of the elastic scattering amplitude variation allowed by unitarity. We discuss the energy dependence of the inelastic diffractive cross-section on the base of this bound and recent LHC data.

    hep-phJ.Phys.G(2017)·2 citations
12. 12*

    LikeDM: likelihood calculator of dark matter detection

    Xiaoyuan Huang🇩🇪 · Yue-Lin Sming Tsai🇯🇵 · Qiang Yuan🇨🇳

    With the large progress in searches for dark matter (DM) particles with indirect and direct methods, we develop a numerical tool that enables fast calculations of the likelihoods of specified DM particle models given a number of observational data, such as charged cosmic rays from space-borne experiments (e.g., PAMELA, AMS-02), gamma-rays from the Fermi space telescope, and underground direct detection experiments. The purpose of this tool --- LikeDM, likelihood calculator for dark matter detection --- is to bridge the gap between a particle model of DM and the observational data. The intermediate steps between these two, including the astrophysical backgrounds, the propagation of charged particles, the analysis of Fermi gamma-ray data, as well as the DM velocity distribution and the nuclear form factor, have been dealt with in the code. We release the first version (v1.0) focusing on the constraints from indirect detection of DM with charged cosmic and gamma rays. Direct detection will be implemented in the next version. This manual describes the framework, usage, and related physics of the code. The code LikeDM can be download from https://likedm.hepforge.org/

    hep-phastro-ph.HEphysics.comp-phphysics.data-anComput.Phys.Commun.(2017)·36 citations
13. 13*

    RG-improved Prediction for 750 GeV Resonance Production at the LHC

    Xiaohui Liu🇺🇸 · Hong Zhang🇺🇸

    We present a renormalization-group (RG) improved prediction for $750$ GeV heavy state production recently seen as the diphoton excess at the LHC. Due to the universality of QCD feature in the threshold region, our result provides reasonable estimate of the K-factor for most existing leading order predictions, independent of the specific nature of the resonance. We consider specifically the spin-$2$ warped Kaluza-Klein graviton model to highlight our calculation. We performed soft gluon resummation near threshold at next-to-next-to-leading logarithmic (NNLL) accuracy together with resumming enhanced corrections from a towers of ${\pi }^2$ due to analytic continuation. We find the resummation effects are significant. When matching our resummed result to next-to-leading order calculation, we find our improved predictions exceed the leading fixed-order results by about $56\%$ ($K=1.56$) for the LHC energies at 13 TeV and 14 TeV, and about $63\%$ ($K=1.63$) for 8 TeV.

    hep-phhep-ex12 citations
14. 14*

    Leptonic decays of D-wave vector quarkonia

    A. Krassnigg🇦🇹 · M. Gomez-Rocha🇮🇹 · T. Hilger🇦🇹

    We give a short and basic introduction to our covariant Dyson-Schwinger-Bethe-Salpeter-equation approach using a rainbow-ladder truncated model of QCD, in which we investigate the leptonic decay properties of heavy quarkonium states in the pseudoscalar and vector channels. Comparing the magnitudes of decay constants, we identify radial 1-- excitations in our calculation with experimental excitations of J/\Psi and \Upsilon. Particular attention is paid to those states regarded as D-wave states in the quark model. We predict e+e- decay width of the \Upsilon(1^3D_1) and \Upsilon(2^3D_1) states of the order of ca. 15 eV or more. We also provide a set of predictions for decay constants of pseudoscalar radial excitations in heavy quarkonia.

    hep-phhep-exJ.Phys.Conf.Ser.(2016)·14 citations
15. 15*

    Quasi-degenerate Neutrino mass models and their significance: A model independent investigation

    S. Roy🇮🇳 · N. N Singh🇮🇳

    The prediction of possible ordering of neutrino masses relies mostly on the model selected. Alienating the $\mu -\tau$ interchange symmetry from discrete flavour symmetry based models, turns the neutrino mass matrix less predictive. But this inspires one to seek the answer from other phenomenological frameworks. We need a proper parametrization of the neutrino mass matrices concerning individual hierarchies. In the present work, we attempt to study the six different cases of Quasi-degenerate (QDN) neutrino models. The related mass matrices, $m_{LL}^{\nu }$ are parametrized with two free parameters ($\alpha ,\eta$) and standard Wolfenstein parameter ($\lambda$). The input mass scale $m_0$ is selected around $\sim 0.08eV$. We begin with a $\mu -\tau$ symmetric neutrino mass matrix tailed by a correction from charged lepton sector. The parametrization accentuates the existence of four independent texture zero building block matrices which are common to all the QDN models under $\mu -\tau$ symmetric framework. These remain invariant irrespective of any choice of solar angle. In our parametrization, the neutrino sector controls the solar angle, whereas the reactor and atmospheric angles are dictated by the charged lepton sector. In the framework of oscillation experiments, cosmological observation and future experiments involving $\beta$-decay and $0\nu \beta \beta$ experiments, all QDN models are tested and a reason to rule out anyone out of the six models is unfounded. A strong preference for ${\sin }^2{\theta }_{12}=0.32$ is observed for QDNH-$TypeA$ model.

    hep-phNPB(2013)·6 citations
16. 16*

    Large loop-coupling enhancement of a heavy pseudoscalar from a light dark sector

    Stefano Di Chiara🇪🇪 · Andi Hektor🇪🇪 · Kristjan Kannike🇪🇪 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪

    The small background and the sensitivity to charged particles via a leading order loop coupling make the diphoton channel a privileged experimental test for new physics models. We propose a simple archetypal scenario to generate a sharp di-photon resonance as a result of threshold enhancements in the effective coupling between a heavy pseudoscalar particle and new vector-like leptons. We therefore study three different scenarios consistent with the current experimental limits and deviating from the Standard Model at the 2~$\sigma$ level. The model also introduces a natural dark matter candidate able to match the observed dark matter abundance and comfortably respect the current direct detection constraints.

    hep-phNPB(2017)·17 citations
17. 17*

    Reanalysis of Rosenbluth measurements of the proton form factors

    A. V. Gramolin🇷🇺 · D. M. Nikolenko🇷🇺

    We present a reanalysis of the data from Stanford Linear Accelerator Center (SLAC) experiments E140 [R. C. Walker et al., Phys. Rev. D 49, 5671 (1994)] and NE11 [L. Andivahis et al., Phys. Rev. D 50, 5491 (1994)] on elastic electron-proton scattering. This work is motivated by recent progress in calculating the corresponding radiative corrections and by the apparent discrepancy between the Rosenbluth and polarization transfer measurements of the proton electromagnetic form factors. New, corrected values for the scattering cross sections are presented, as well as a new form factor fit in the $Q^2$ range from 1 to 8.83 ${\text{GeV}}^2$. We also provide a complete set of revised formulas to account for radiative corrections in single-arm measurements of unpolarized elastic electron-proton scattering.

    ↳ nucl-exhep-exhep-phPRC(2016)·35 citations
18. 18*

    Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations With the Fermi Large Area Telescope

    The Fermi-LAT Collaboration

    We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the $\gamma$-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using six years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above $5\times 10^{-12}{\mathrm{GeV}}^{-1}$ for ALP masses $0.5\lesssim m_a\lesssim 5$ neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the $\gamma$-ray opacity of the Universe.

    ↳ astro-ph.HEhep-phPRL(2016)·298 citations
19. 19*

    The late Universe with non-linear interaction in the dark sector: the coincidence problem

    Mariam Bouhmadi-López🇵🇹 · João Morais🇪🇸 · Alexander Zhuk🇺🇦

    We study the Universe at the late stage of its evolution and deep inside the cell of uniformity. At such a scale the Universe is highly inhomogeneous and filled with discretely distributed inhomogeneities in the form of galaxies and groups of galaxies. As a matter source, we consider dark matter (DM) and dark energy (DE) with a non-linear interaction $Q=3\mathcal{H}\gamma {\bar{\epsilon }}_{\mathrm{DE}}{\bar{\epsilon }}_{\mathrm{DM}}/({\bar{\epsilon }}_{\mathrm{DE}}+{\bar{\epsilon }}_{\mathrm{DM}})$, where $\gamma$ is a constant. We assume that DM is pressureless and DE has a constant equation of state parameter $w$. In the considered model, the energy densities of the dark sector components present a scaling behaviour with ${\bar{\epsilon }}_{\mathrm{DM}}/{\bar{\epsilon }}_{\mathrm{DE}}\sim {\left(a_0/a\right)}^{-3(w+\gamma )}$. We investigate the possibility that the perturbations of DM and DE, which are interacting among themselves, could be coupled to the galaxies with the former being concentrated around them. To carry our analysis, we consider the theory of scalar perturbations (within the mechanical approach), and obtain the sets of parameters $(w,\gamma )$ which do not contradict it. We conclude that two sets: $(w=-2/3,\gamma =1/3)$ and $(w=-1,\gamma =1/3)$ are of special interest. First, the energy densities of DM and DE on these cases are concentrated around galaxies confirming that they are coupled fluids. Second, we show that for both of them, the coincidence problem is less severe than in the standard $\Lambda$CDM. Third, the set $(w=-1,\gamma =1/3)$ is within the observational constraints. Finally, we also obtain an expression for the gravitational potential in the considered model.

    ↳ gr-qcastro-ph.COhep-phhep-thPhys.Dark Univ.(2016)·22 citations
20. 20*

    Meaning of the nuclear wave function

    John D. Terry🇺🇸 · Gerald A. Miller🇺🇸

    Background The intense current experimental interest in studying the structure of the deuteron and using it to enable accurate studies of neutron structure motivate us to examine the four-dimensional space-time nature of the nuclear wave function, and the various approximations used to reduce it to an object that depends only on three spatial variables. Purpose: The aim is to determine if the ability to understand and analyze measured experimental cross sections is compromised by making the reduction from four to three dimensions. Method: Simple, exactly-calculable, covariant models of a bound-state wave state wave function (a scalar boson made of two constituent-scalar bosons) with parameters chosen to represent a deuteron are used to investigate the accuracy of using different approximations to the nuclear wave function to compute the quasi-elastic scattering cross section. Four different versions of the wave function are defined (light-front spectator, light-front, light-front with scaling and non-relativistic) and used to compute the cross sections as a function of how far off the mass-shell (how virtual) is the struck constituent. Results: We show that making an exact calculation of the quasi-elastic scattering cross section involves using the light-front spectator wave function. All of the other approaches fail to reproduce the model exact calculation if the value of Bjorken $x$ differs from unity. The model is extended to consider an essential effect of spin to show that constituent nucleons cannot be treated as being on their mass shell even when taking the matrix element of a `good' current. Conclusions: It is necessary to develop realistic light-front spectator wave functions to meet the needs of current and planned experiments.

    ↳ nucl-thhep-phnucl-exPRC(2016)·1 citation
21. 21*

    Tuning the Cosmological Constant, Broken Scale Invariance, Unitarity

    Stefan Forste🇩🇪 · Paul Manz🇩🇪

    We study gravity coupled to a cosmological constant and a scale but not conformally invariant sector. In Minkowski vacuum, scale invariance is spontaneously broken. We consider small fluctuations around the Minkowski vacuum. At the linearised level we find that the trace of metric perturbations receives a positive or negative mass squared contribution. However, only for the Fierz-Pauli combination the theory is free of ghosts. The mass term for the trace of metric perturbations can be cancelled by explicitly breaking scale invariance. This reintroduces fine-tuning. Models based on four form field strength show similarities with explicit scale symmetry breaking due to quantisation conditions.

    ↳ hep-thgr-qchep-phJCAP(2016)·1 citation
22. 22*

    Variational principle for theories with dissipation from analytic continuation

    Stefan Floerchinger🇩🇪

    The analytic continuation from the Euclidean domain to real space of the one-particle irreducible quantum effective action is discussed in the context of generalized local equilibrium states. Discontinuous terms associated with dissipative behavior are parametrized in terms of a conveniently defined sign operator. A generalized variational principle is then formulated, which allows to obtain causal and real dissipative equations of motion from the analytically continued quantum effective action. Differential equations derived from the implications of general covariance determine the space-time evolution of the temperature and fluid velocity fields and allow for a discussion of entropy production including a local form of the second law of thermodynamics.

    ↳ hep-thgr-qchep-phJHEP(2016)·20 citations
23. 23*

    The Optical Potential on the Lattice

    Dimitri Agadjanov🇩🇪 · Michael Doring🇺🇸 · Maxim Mai🇩🇪 · Ulf-G. Meißner🇩🇪 · Akaki Rusetsky🇩🇪

    The extraction of hadron-hadron scattering parameters from lattice data by using the Lüscher approach becomes increasingly complicated in the presence of inelastic channels. We propose a method for the direct extraction of the complex hadron-hadron optical potential on the lattice, which does not require the use of the multi-channel Lüscher formalism. Moreover, this method is applicable without modifications if some inelastic channels contain three or more particles.

    ↳ hep-lathep-phJHEP(2016)·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.