Thu·Oct 22, 2015Thursday·October 22, 2015

1. 01*

   ManeParse: Mathematica Toolbox for PDF Uncertainties and Application to New Physics Searches

   Eric Godat🇺🇸

   As the LHC begins Run 2 at an even higher energy, one of the top priorities will be to search for new particles (possibly from SUSY) at the highest energy scales. In addition to direct production of new particles, they can mix with Standard Model (SM) particles to yield discrepancies from the usual predictions. To distinguish this new physics from old uncertainties, we need tools to precisely quantify the uncertainties of the SM predictions. Here we present a versatile set of utility functions built with Mathematica that is capable of working with a variety of PDF formats including the recent LHAPDF6 format. This software can perform PDF calculations within the Mathematica framework and compare results from different PDF collaborations. The package includes both the central PDF value as well as the full error sets needed for PDF uncertainty analysis; a variety of sample error definitions are implemented. We demonstrate this package for the case of a new heavy scalar particle production at the LHC.

   hep-ph5 citations
2. 02*

   Roy-Steiner-equation analysis of pion-nucleon scattering

   Martin Hoferichter🇺🇸 · Jacobo Ruiz de Elvira🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪

   We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process $\pi \pi \to \bar{N}N$, as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process $\pi N\to \pi N$ and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon $\sigma$-term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity, crossing symmetry, and pionic-atom data. We perform the matching to chiral perturbation theory in the subthreshold region and detail the consequences for the chiral convergence of the threshold parameters and the nucleon mass.

   hep-phhep-latnucl-exnucl-thPhys.Rept.(2016)·324 citations
3. 03*

   The spontaneous ${\mathbb{Z}}_2$ breaking Twin Higgs

   Hugues Beauchesne🇨🇦 · Kevin Earl🇨🇦 · Thomas Grégoire🇨🇦

   The Twin Higgs model seeks to address the little hierarchy problem by making the Higgs a pseudo-Goldstone of a global $SU(4)$ symmetry that is spontaneously broken to $SU(3)$. Gauge and Yukawa couplings, which explicitly break $SU(4)$, enjoy a discrete ${\mathbb{Z}}_2$ symmetry that accidentally maintains $SU(4)$ at the quadratic level and therefore keeps the Higgs light. Contrary to most beyond the Standard Model theories, the quadratically divergent corrections to the Higgs mass are cancelled by a mirror sector, which is uncharged under the Standard Model groups. However, the Twin Higgs with an exact ${\mathbb{Z}}_2$ symmetry leads to equal vevs in the Standard Model and mirror sectors, which is phenomenologically unviable. An explicit ${\mathbb{Z}}_2$ breaking potential must then be introduced and tuned against the $SU(4)$ breaking terms to produce a hierarchy of vevs between the two sectors. This leads to a moderate but non-negligible tuning. We propose a model to alleviate this tuning, without the need for an explicit ${\mathbb{Z}}_2$ breaking sector. The model consists of two $SU(4)$ fundamental Higgses, one whose vacuum preserves ${\mathbb{Z}}_2$ and one whose vacuum breaks it. As the interactions between the two Higgses are turned on, the ${\mathbb{Z}}_2$ breaking is transmitted from the broken to the unbroken sector and a small hierarchy of vevs is naturally produced. The presence of an effective tadpole and feedback between the two Higgses lead to a sizable improvement of the tuning. The resulting Higgs boson is naturally very Standard Model like.

   hep-phJHEP(2016)·51 citations
4. 04*

   MSSM4G: Reviving Bino Dark Matter with Vector-like 4th Generation Particles

   Mohammad Abdullah🇺🇸 · Jonathan L. Feng🇺🇸

   We supplement the minimal supersymmetric standard model (MSSM) with vector-like copies of standard model particles. Such 4th generation particles can raise the Higgs boson mass to the observed value without requiring very heavy superpartners, improving naturalness and the prospects for discovering supersymmetry at the LHC. Here we show that these new particles are also motivated cosmologically: in the MSSM, pure Bino dark matter typically overcloses the Universe, but 4th generation particles open up new annihilation channels, allowing Binos to have the correct thermal relic density without resonances or co-annihilation. We show that this can be done in a sizable region of parameter space while preserving gauge coupling unification and satisfying constraints from collider, Higgs, precision electroweak, and flavor physics.

   hep-phastro-ph.COPRD(2016)·11 citations
5. 05*

   Singlet-Doublet Dirac Dark Matter

   Carlos E. Yaguna🇩🇪

   We analyze a simple extension of the Standard Model where the dark matter particle is a Dirac fermion that is mixture of a singlet and an SU(2) doublet. The model contains only four free parameters: the singlet and the doublet masses and two new Yukawa couplings. Direct detection bounds in this model are very strong and require the dark matter particle to be singlet-like. As a result, its relic density has to be obtained via coannihilations with the doublet. We find that the dark matter mass should be below 750 GeV, that the singlet-doublet mass difference cannot exceed 9%, and that direct detection experiments offer the best chance to probe this scenario. Finally, we also show that this model can effectively arise in well-motivated extensions of the Standard Model.

   hep-phPRD(2015)·49 citations
6. 06*

   Higgs-portal Scalar Dark Matter: Scattering Cross Section and Observable Limits

   Huayong Han🇨🇳 · Sibo Zheng🇨🇳

   The simplest Higgs-portal dark matter model is studied in the light of dark matter self-interacting effects on the formation of large scale structures. We show the direct detection limits on the resonant and large mass regions. Finally, we also compare these limits with those at the LHC and Xenon 1T experiments.

   hep-phastro-ph.CONPB(2017)·28 citations
7. 07*

   New developments in the statistical approach of parton distributions

   Jacques Soffer🇺🇸 · Claude Bourrely🇫🇷

   The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in terms of a rather small number of free parameters. There are several challenging issues. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm }$ production in $\bar{p}p$ and $pp$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.

   hep-phActa Phys.Polon.Supp.(2015)·0 citations
8. 08*

   Etaprime interactions with nucleons and nuclei

   Steven D. Bass🇦🇹 · Pawel Moskal🇵🇱

   We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.

   hep-phnucl-exnucl-thActa Phys.Polon.B(2016)·11 citations
9. 09*

   Prospects for Supersymmetry at the LHC & Beyond

   John Ellis🇬🇧

   Run 1 of the LHC has provided three new motivations for supersymmetry: the need to stabilize the electroweak vacuum, the mass of the Higgs boson, and the fact that its couplings are Standard Model-like (so far). The prospects for discovering (and measuring) supersymmetry during future runs of the LHC are discussed in the frameworks of the constrained MSSM (CMSSM), models with non-universal soft supersymmetry-breaking contributions to Higgs masses (NUHM1,2) and the phenomenological MSSM with 10 arbitrary soft supersymmetry-breaking parameters (pMSSM10). In addition to the classic searches for missing transverse energy, searches for long-lived charged sparticles may also be promising. If supersymmetry does show up at the LHC, there are good prospects for measurements of the spectrum that can be compared with the indirect indications from other experiments. On the other hand, a higher-energy future circular proton-proton collider may be the best option for discovering supersymmetry if it does not appear at the LHC.

   hep-phhep-exPoS(2015)·5 citations
10. 10*

    Relaxation of the chiral imbalance and the generation of magnetic fields in magnetars

    Maxim Dvornikov (IZMIRAN, Tomsk State University, University of Hamburg)🇷🇺

    The model for the generation of magnetic fields in a neutron star, based on the magnetic field instability caused by the electroweak interaction between electrons and nucleons, is developed. Using the methods of the quantum field theory, the helicity flip rate of electrons in their scattering off protons in dense matter of a neutron star is calculated. The influence of the electroweak interaction between electrons and background nucleons on the process of the helicity flip is studied. The kinetic equation for the evolution of the chital imbalance is derived. The obtained results are applied for the description of the magnetic fields evolution in magnetars.

    hep-phastro-ph.HEJ.Exp.Theor.Phys.(2016)·22 citations
11. 11*

    Type I+III Seesaw Mechanism and CP Violation for Leptogenesis

    Edison T. Franco🇧🇷

    A seesaw mechanism is presented in the neutrino sector and a new phase of CP violation ($\alpha$) emerges in the interplay between the type-I and type-III seesaw schemes. This phase is inside the mixing term, and thus it cannot be rotated away in the Yukawa Lagrangian and, therefore, the heavy symmetry states cannot be in a diagonal weak basis in the broken phase. Some particular descriptions are analyzed suggesting that if the usual Yukawa couplings are suppressed, leptogenesis still occurs due to a new interacting vertex with fermion triplet $T$, fermion singlets $N$, and an ad-hoc scalar triplet, $\Sigma$, which now is included to mediate the interactions. The evaluated CP violation is enough to generate the observed matter-antimatter asymmetry even in the minimal $1N+1T$ case (independently of $\alpha$) or in the $2N+1T$ approach (controlled by $\alpha$). The latter introduces more CP contributions to leptogenesis due to new diagrams which are now possible even with the suppressed imaginary part of the standard Yukawa couplings and can induce the observed baryon-to-photon ratio.

    hep-phPRD(2015)·14 citations
12. 12*

    Watson's theorem and the $N\Delta (1232)$ axial transition

    L. Alvarez-Ruso🇪🇸 · E. Hernández🇪🇸 · J. Nieves🇪🇸 · M.J. Vicente Vacas🇪🇸

    We present a new determination of the $N\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez {\it et al.} [Phys. Rev. D76, 033005 (2007)] is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.

    hep-phhep-exnucl-exnucl-thPRD(2016)·54 citations
13. 13*

    Neutral hidden charm pentaquark states $P_c^0(4380)$ and $P_c^0(4450)$ in ${\pi }^{-}p\to J/\psi n$ reaction

    Qi-Fang Lü🇨🇳 · Xiao-Yun Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Xu-Rong Chen🇨🇳 · Yu-Bing Dong🇨🇳

    We investigate the neutral hidden charm pentaquark states $P_c^0(4380)$ and $P_c^0(4450)$ in ${\pi }^{-}p\to J/\psi n$ reaction within an effective Lagrangian approach. The background contributions for the process mainly come from $t$-channel $\pi$ and $\rho$ meson exchanges. The contributions of $P_c^0(4380)$ and $P_c^0(4450)$ states give clear peak structures in the magnitude of 1 $\mu$b at center of mass energy 4.38 GeV and 4.45 GeV in the total cross sections. Hence, this reaction may provide a new good platform to search for neutral $P_c$ states. It is expected that our estimated total cross sections together with the angular distributions can be tested by future experiments at J-PARC.

    hep-phhep-exnucl-thPRD(2016)·51 citations
14. 14*

    Precise Prediction of the Dark Matter Relic Density within the MSSM

    Julia Harz🇬🇧 · Björn Herrmann🇫🇷 · Michael Klasen🇩🇪 · Karol Kovarik🇩🇪 · Patrick Steppeler🇩🇪

    With the latest Planck results the dark matter relic density is determined to an unprecedented precision. In order to reduce current theoretical uncertainties in the dark matter relic density prediction, we have calculated next-to-leading order SUSY-QCD corrections to neutralino (co)annihilation processes including Coulomb enhancement effects. We demonstrate that these corrections can have significant impact on the cosmologically favoured MSSM parameter space and are thus of general interest for parameter studies and global fits.

    hep-phPoS(2015)·6 citations
15. 15*

    Phenomenology of the Georgi-Machacek model at future electron-positron colliders

    Cheng-Wei Chiang🇹🇼 · Shinya Kanemura🇯🇵 · Kei Yagyu🇬🇧

    We study the phenomenology of the exotic Higgs bosons in the Georgi-Machacek model at future electron-positron colliders such as the International Linear Collider (ILC), assuming the collision energies of 500 GeV and 1 TeV. We show that the existence of the neutral and singly-charged Higgs bosons in the 5-plet representation under the custodial $SU(2{)}_V$ symmetry can be readily identified by studying various energy and invariant mass distributions of the $W^{+}{W}^{-}Z$ final state. Moreover, their masses can be determined with sufficiently high precision to test the mass degeneracy, a feature due to the custodial symmetry of the model. A synergy between such searches at the ILC and the doubly-charged Higgs search at the LHC will make the 5-plet Higgs boson study more comprehensive.

    hep-phPRD(2016)·46 citations
16. 16*

    Impact of Neutrinoless Double Beta Decay on Models of Baryogenesis

    Frank F. Deppisch🇬🇧 · Julia Harz🇬🇧 · Wei-Chih Huang🇬🇧

    Interactions that manifest themselves as lepton number violating processes at low energies in combination with sphaleron transitions typically erase any pre-existing baryon asymmetry of the Universe. We demonstrate in a model independent approach that the observation of neutrinoless double beta decay would impose a stringent constraint on mechanisms of high-scale baryogenesis, including leptogenesis scenarios. Further, we discuss the potential of the LHC to model independently exclude high-scale leptogenesis scenarios when observing lepton number violating processes. In combination with the observation of lepton flavor violating processes, we can further strengthen this argument, closing the loophole of asymmetries being stored in different lepton flavors.

    hep-phPoS(2015)·2 citations
17. 17*

    Probing the Hidden Higgs Bosons of the $Y=0$ Triplet- and Singlet-Extended Supersymmetric Standard Model at the LHC

    Priyotosh Bandyopadhyay🇮🇹 · Claudio Coriano🇮🇹 · Antonio Costantini🇮🇹

    We investigate the scalar sector in an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet beside the $SU(2)$ scalar doublets. In particular, we focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. We analyze the exotic decay of the discovered Higgs $(h_{125})$ into two light (hidden) Higgs bosons present in the extension. The latter are allowed by the uncertainties in the Higgs decay $h_{125}\to W{W}^{\ast }$, $h_{125}\to Z{Z}^{\ast }$ and $h_{125}\to \gamma \gamma$. The study of the parameter space for such additional scalars/pseudoscalars decay of the Higgs is performed in the gluon fusion channel. The extra hidden Higgs bosons of the enlarged scalar sector, if they exist, will then decay into lighter fermion paris, i.e., $b\bar{b}$, $\tau \bar{\tau }$ and $\mu \bar{\mu }$ via the mixing with the doublets. A detailed simulation using PYTHIA of the $2b+2\tau$, $\ge 3\tau$, $2b+2\mu$ and $2\tau +2\mu$ final states is presented. From our analysis we conclude that, depending on the selected benchmark points, such decay modes can be explored with an integrated luminosity of 25 fb${}^{-1}$ at the LHC at a center of mass energy of 13 TeV.

    hep-phJHEP(2015)·29 citations
18. 18*

    $D_{s0}^{\ast }(2317{)}^{+}$ in the decay of $B_c$ into $J/\psi DK$

    Zhi-Feng Sun🇪🇸 · M. Bayar🇹🇷 · P. Fernandez-Soler🇪🇸 · E. Oset🇪🇸

    In this paper we study the relationship between the $D_{s0}^{\ast }(2317{)}^{+}$ resonance and the decay of the $B_c$ meson into $J/\psi DK$. In this process, the $B_c$ meson decays first into $J/\psi$ and the quark pair $c\bar{s}$, and then the quark pair hadronizes into $DK$ or $D_s\eta$ components, which undergo final state interaction. This final state interaction, generating the $D_{s0}^{\ast }(2317{)}^{+}$ resonance, is described by the chiral unitary approach. With the parameters which allow us to match the pole position of the $D_{s0}^{\ast }(2317{)}^{+}$, we obtain the $DK$ invariant mass distribution of the decay $B_c\to J/\psi DK$, and also the rate for $B_c\to J/\psi D_{s0}^{\ast }(2317)$. The ratio of these two magnitude is then predicted.

    hep-phPRD(2016)·20 citations
19. 19*

    Implementing inverse seesaw mechanism in SU(3)xSU(4)xU(1) gauge models

    Adrian Palcu🇷🇴

    Generating appropriate tiny neutrino masses via inverse seesaw mechanism within the framework of a particular SU(3)xSU(4)xU(1) gauge model is the main outcome of this letter. It is achieved by simply adding three singlet exotic Majorana neutrinos to the usual ones included in the three lepton quadruplet representations. The theoretical device of treating gauge models with high symmetries is the general method by Cotaescu. It provides us with a unique free parameter (a) to be tuned in order to get a realistic mass spectrum for the gauge bosons and charged fermions in the model. The overall breaking scale can be set around 1-10 TeV so its phenomenology is quite testable at present facilities.

    hep-phInt.J.Theor.Phys.(2017)·13 citations
20. 20*

    Concerning the variability of beta-decay measurements

    P.A. Sturrock🇺🇸 · E. Fischbach🇺🇸 · A. Parkhomov🇷🇺 · J.D. Scargle🇺🇸 · G. Steinitz🇮🇱

    Many experiments have been carried out to study the beta-decay rates of a variety of nuclides, and many - but not all - of these experiments yield evidence of variability of these rates. While there is as yet no accepted theory to explain patterns in the results, a number of conjectures have been proposed. We discuss three prominent conjectures (which are not mutually exclusive) - that variability of beta-decay rates may be due to (a) environmental influences, (b) solar neutrinos, and (c) cosmic neutrinos. We find evidence in support of each of these conjectures.

    ↳ nucl-exhep-ph11 citations
21. 21*

    The Quest for B Modes from Inflationary Gravitational Waves

    Marc Kamionkowski🇺🇸 · Ely D. Kovetz🇺🇸

    The search for the curl component (B mode) in the cosmic microwave background (CMB) polarization induced by inflationary gravitational waves is described. The canonical single-field slow-roll model of inflation is presented, and we explain the quantum production of primordial density perturbations and gravitational waves. It is shown how these gravitational waves then give rise to polarization in the CMB. We then describe the geometric decomposition of the CMB polarization pattern into a curl-free component (E mode) and curl component (B mode) and show explicitly that gravitational waves induce B modes. We discuss the B modes induced by gravitational lensing and by Galactic foregrounds and show how both are distinguished from those induced by inflationary gravitational waves. Issues involved in the experimental pursuit of these B modes are described, and we summarize some of the strategies being pursued. We close with a brief discussion of some other avenues toward detecting/characterizing the inflationary gravitational-wave background.

    ↳ astro-ph.COgr-qchep-phhep-thAnn.Rev.Astron.Astrophys.(2016)·457 citations
22. 22*

    Spectrum and Entropy of C-systems. MIXMAX random number generator

    Konstantin Savvidy🇬🇷 · George Savvidy🇬🇷

    The uniformly hyperbolic Anosov C-systems defined on a torus have very strong instability of their trajectories, as strong as it can be in principle. These systems have exponential instability of all their trajectories and as such have mixing of all orders, nonzero Kolmogorov entropy and a countable set of everywhere dense periodic trajectories. In this paper we are studying the properties of their spectrum and of the entropy. For a two-parameter family of C-system operators A(N,s), parametrised by the integers N and s, we found the universal limiting form of the spectrum, the dependence of entropy on N and the period of its trajectories on a rational sublattice. One can deduce from this result that the entropy and the periods are sharply increasing with N. We present a new three-parameter family of C-operators A(N,s,m) and analyse the dependence of its spectrum and of the entropy on the parameter m. We developed our earlier suggestion to use these tuneable Anosov C-systems for multipurpos Monte-Carlo simulations. The MIXMAX family of random number generators based on Anosov C-systems provide high quality statistical properties, thanks to their large entropy, have the best combination of speed, reasonable size of the state, tuneable parameters and availability for implementing the parallelisation.

    ↳ math.DShep-lathep-phChaos Solitons Fractals(2016)·23 citations
23. 23*

    Phenomenological analysis of near threshold periodic modulations of the proton timelike form factor

    A. Bianconi🇮🇹 · E. Tomasi-Gustafsson🇫🇷

    We have recently highlighted the presence of a periodically oscillating 10 \% modulation in the BABAR data on the proton timelike form factors, in the reaction $e^{+}+e^{-}$ $\to$ $\bar{p}+p$. Here we deepen our previous data analysis, and confirm that in the case of several standard parametrizations it is possible to write the form factor in the form $F_0$ $+$ $F_{osc}$, where $F_0$ is a parametrization expressing the long-range trend of the form factor (for $q^2$ ranging from the $\bar{p}p$ threshold to 36 GeV${}^2$), and $F_{osc}$ is a function of the form $\exp (-Bp)\cos (Cp)$, where $p$ is the relative momentum of the final $\bar{p}p$ pair. Error bars allow for a clean identification of the main features of this modulation for $q^2$ $<$ 10 GeV${}^2$. Assuming this oscillatory modulation to be an effect of final state interactions between the forming proton and the antiproton, we propose a phenomenological model based on a double-layer imaginary optical potential. This potential is flux-absorbing when the distance between the proton and antiproton centers of mass is $\gtrsim$ 1.7-1.8 fm and flux-generating when it is $\lesssim$ 1.7-1.8 fm. The main features of the oscillations may be reproduced with some freedom in the potential parameters, but the transition between the two layers must be sudden (0-0.2 fm) to get the correct oscillation period. The flux-absorbing part of the $\bar{p}p$ interaction is due to the annihilation of $\bar{p}p$ pairs into multi-meson states. We interpret the flux-creating part of the potential as due to the creation of a $1/q$-ranged state when the virtual photon decays into a set of current quarks and antiquarks, including heavy ones, that may exist for a short time. The decay of these large mass states leads to an intermediate stage regeneration of the $\bar{p}p$ channel.

    ↳ nucl-thhep-phPRC(2016)·52 citations
24. 24*

    Cross-platform validation and analysis environment for particle physics

    S.V. Chekanov🇺🇸 · I. Pogrebnyak🇺🇸 · D. Wilbern🇺🇸

    A multi-platform validation and analysis framework for public Monte Carlo simulation for high-energy particle collisions is discussed. The front-end of this framework uses the Python programming language, while the back-end is written in Java, which provides a multi-platform environment that can be run from a web browser and can easily be deployed at the grid sites. The analysis package includes all major software tools used in high-energy physics, such as Lorentz vectors, jet algorithms, histogram packages, graphic canvases, and tools for providing data access. This multi-platform software suite, designed to minimize OS-specific maintenance and deployment time, is used for online validation of Monte Carlo event samples through a web interface.

    ↳ physics.comp-phhep-phComput.Phys.Commun.(2017)·2 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.