Thu·Dec 3, 2015Thursday·December 3, 2015

1. 01*

   Multiboson production in W' decays

   J. A. Aguilar-Saavedra🇪🇸 · F. R. Joaquim🇵🇹

   In models with an extra $\text{SU}(2{)}_R$ gauge group and an extended scalar sector, the cascade decays of the $W^{\prime }$ boson can provide various multiboson signals. In particular, diboson decays $W^{\prime }\to WZ$ can be suppressed while $W^{\prime }\to WZX$, with $X$ one of the scalars present in the model, can reach branching ratios around 4%. We discuss these multiboson signals focusing on possible interpretations of the ATLAS excess in fat jet pair production.

   hep-phhep-exJHEP(2016)·31 citations
2. 02*

   Narrow Nucleon-$\psi (2S)$ Bound State and LHCb Pentaquarks

   Michael I. Eides🇺🇸 · Victor Yu.Petrov🇷🇺 · Maxim V. Polyakov🇷🇺

   We interpret the newly discovered pentaquark $P_c(4450)$ as a bound state of charmonium $\psi (2S)$ and the nucleon. The binding potential is due to charmonium-nucleon interaction that in the heavy quark approximation is proportional to the product of the charmonium chromoelectric polarizability and the nucleon energy-momentum distribution. We use the large $N_c$ expansion to estimate the quarkonium polarizability and calculate the nucleon properties in the framework of the mean-field picture of light baryons. Two almost degenerate states $J^P=(1/2{)}^{-}$ and $J^P=(3/2{)}^{-}$ are predicted at the position of the $P_c(4450)$ pentaquark. We find that the nucleon-$\psi (2S)$ bound state has a naturally narrow width in the range of tens of MeV. The unitary multiplet partners of the $P_c(4450)$ pentaquark and the generalization to $b\bar{b}$-nucleon pentaquark bound states are discussed.

   hep-phhep-exnucl-exPRD(2016)·99 citations
3. 03*

   CP Violation in Heavy MSSM Higgs Scenarios

   M. Carena🇺🇸 · J. Ellis🇬🇧 · J. S. Lee🇰🇷 · A. Pilaftsis🇬🇧 · C. E. M. Wagner🇺🇸

   We introduce and explore new heavy Higgs scenarios in the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation, which have important phenomenological implications that may be testable at the LHC. For soft supersymmetry-breaking scales M_S above a few TeV and a charged Higgs boson mass M_H+ above a few hundred GeV, new physics effects including those from explicit CP violation decouple from the light Higgs boson sector. However, such effects can significantly alter the phenomenology of the heavy Higgs bosons while still being consistent with constraints from low-energy observables, for instance electric dipole moments. To consider scenarios with a charged Higgs boson much heavier than the Standard Model (SM) particles but much lighter than the supersymmetric particles, we revisit previous calculations of the MSSM Higgs sector. We compute the Higgs boson masses in the presence of CP violating phases, implementing improved matching and renormalization group (RG) effects, as well as two-loop RG effects from the effective two-Higgs Doublet Model (2HDM) scale M_H+ to the scale M_S. We illustrate the possibility of non-decoupling CP-violating effects in the heavy Higgs sector using new benchmark scenarios named CPX4LHC.

   hep-phJHEP(2016)·61 citations
4. 04*

   Measuring c-quark polarization in W+c samples at ATLAS and CMS

   Yevgeny Kats🇮🇱

   The process $pp\to W^{-}c$ produces polarized charm quarks. The polarization is expected to be partly retained in ${\Lambda }_c$ baryons when those form in the $c$-quark hadronization. We argue that it will likely be possible for ATLAS and CMS to measure the ${\Lambda }_c$ polarization in the $W$+$c$ samples in Run 2 of the LHC. This can become the first measurement ever of a longitudinal polarization of charm quarks. Its results will provide a unique input to the understanding of polarization transfer in fragmentation. They will also allow applying the same measurement technique to other (e.g., new physics) samples of charm quarks in which the polarization is a priori unknown. The proposed analysis is similar to the ATLAS and CMS measurements of the $W$+$c$ cross section in the 7 TeV run that used reconstructed $D$-meson decays for charm tagging.

   hep-phhep-exJHEP(2016)·10 citations
5. 05*

   The Scalar Triplet Contribution to Lepton Flavour Violation and Neutrinoless Double Beta Decay in Left-Right Symmetric Model

   Gulab Bambhaniya🇮🇳 · P. S. Bhupal Dev🇩🇪 · Srubabati Goswami🇮🇳 · Manimala Mitra🇮🇳

   We analyse in detail the scalar triplet contribution to the low-energy lepton flavour violating (LFV) and lepton number violating (LNV) processes within a TeV-scale left-right symmetric framework. We show that in both type-I and type-II seesaw dominance for the light neutrino masses, the triplet of mass comparable to or smaller than the largest right-handed neutrino mass scale can give sizeable contribution to the LFV processes, except in the quasi-degenerate limit of light neutrino masses, where a suppression can occur due to cancellations. In particular, a moderate value of the heaviest neutrino to scalar triplet mass ratio $r\lesssim \mathcal{O}(1)$ is still experimentally allowed and can be explored in the future LFV experiments. Similarly, the contribution of a relatively light triplet to the LNV process of neutrinoless double beta decay could be significant, disfavouring a part of the model parameter space otherwise allowed by LFV constraints. Nevertheless, we find regions of parameter space consistent with both LFV and LNV searches, for which the values of the total effective neutrino mass can be accessible to the next generation ton-scale experiments. Such light triplets can also be directly searched for at the LHC, thus providing a complementary probe of this scenario. Finally, we also study the implications of the triplet contribution for the left-right symmetric model interpretation of the recent diboson anomaly at the LHC.

   hep-phhep-exJHEP(2016)·72 citations
6. 06*

   Mueller-Navelet jets at the LHC

   B. Ducloué🇫🇮 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

   We report on our NLL BFKL studies of Mueller-Navelet jets. We first perform a complete NLL BFKL analysis supplemented by a BLM renormalization scale fixing procedure, which is successfully compared with recent CMS data. Second, we argue for the need of a measurement of an asymmetric jet configuration in order to perform a valuable comparison with fixed order approaches. Third, we predict that the energy-momentum violation is rather tiny in the NLL BFKL approach, for an asymmetric jet configuration. Finally, we argue that the double parton scattering contribution is negligible in the kinematics of actual CMS measurements.

   hep-phhep-exActa Phys.Polon.Supp.(2015)·0 citations
7. 07*

   Light mesons in QCD and unquenching effects from the 3PI effective action

   Richard Williams🇩🇪 · Christian S. Fischer🇩🇪 · Walter Heupel🇩🇪

   We investigate the impact of unquenching effects on QCD Green's functions, in the form of quark-loop contributions to both the gluon propagator and three-gluon vertex, in a three-loop inspired truncation of the three-particle irreducible (3PI) effective action. The fully coupled system of Dyson-Schwinger equations for the quark-gluon-, ghost-gluon- and three-gluon vertices, together with the quark propagator, are solved self-consistently; our only input are the ghost and gluon propagators themselves that are constrained by calculations within Lattice QCD. We find that the two different unquenching effects have roughly equal, but opposite, impact on the quark-gluon vertex and quark propagator, with an overall negative impact on the latter. By taking further derivatives of the 3PI effective action, we construct the corresponding quark-antiquark kernel of the Bethe-Salpeter equation for mesons. The leading component is gluon exchange between two fully-dressed quark-gluon vertices, thus introducing for the first time an obvious scalar-scalar component to the binding. We gain access to time-like properties of bound-states by analytically continuing the coupled system of Dyson--Schwinger equations to the complex plane. We observe that the vector axial-vector splitting is in accord with experiment and that the lightest quark-antiquark scalar meson is above 1 GeV in mass.

   hep-phhep-latnucl-thPRD(2016)·225 citations
8. 08*

   Prospects for dark matter detection with inelastic transitions of xenon

   Christopher McCabe🇳🇱

   Dark matter can scatter and excite a nucleus to a low-lying excitation in a direct detection experiment. This signature is distinct from the canonical elastic scattering signal because the inelastic signal also contains the energy deposited from the subsequent prompt de-excitation of the nucleus. A measurement of the elastic and inelastic signal will allow a single experiment to distinguish between a spin-independent and spin-dependent interaction. For the first time, we characterise the inelastic signal for two-phase xenon detectors in which dark matter inelastically scatters off the Xe-129 or Xe-131 isotope. We do this by implementing a realistic simulation of a typical tonne-scale two-phase xenon detector and by carefully estimating the relevant background signals. With our detector simulation, we explore whether the inelastic signal from the axial-vector interaction is detectable with upcoming tonne-scale detectors. We find that two-phase detectors allow for some discrimination between signal and background so that it is possible to detect dark matter that inelastically scatters off either the Xe-129 or Xe-131 isotope for dark matter particles that are heavier than approximately 100 GeV. If, after two years of data, the XENON1T search for elastic scattering nuclei finds no evidence for dark matter, the possibility of ever detecting an inelastic signal from the axial-vector interaction will be almost entirely excluded.

   hep-phastro-ph.COhep-exJCAP(2016)·41 citations
9. 09*

   Alternatives to an Elementary Higgs

   Csaba Csaki🇺🇸 · Christophe Grojean🇩🇪 · John Terning🇺🇸

   We review strongly coupled and extra dimensional models of electroweak symmetry breaking. Models examined include warped extra dimensions, bulk Higgs, "little" Higgs, dilaton Higgs, composite Higgs, twin Higgs, quantum critical Higgs, and "fat" SUSY Higgs. We also discuss current bounds and future LHC searches for this class of models.

   hep-phhep-exRMP(2016)·78 citations
10. 10*

    Novel Collider and Dark Matter Phenomenology of a Top-philic Z'

    Peter Cox🇦🇺 · Anibal D. Medina🇦🇺 · Tirtha Sankar Ray🇮🇳 · Andrew Spray🇦🇺

    We consider extending the Standard Model by including an additional Abelian gauge group broken at low energies under which the right-handed top quark is the only effectively charged Standard Model fermion. The associated gauge boson $(Z^{\prime })$ is then naturally top-philic and couples only to the rest of the SM particle content at loop-level or via kinetic mixing with the hypercharge gauge boson which is assumed to be small. Working at the effective theory level, we demonstrate that such a minimal extension allows for an improved fitting of the $\sim 2\sigma$ excess observed in $t\bar{t}h$ searches at the LHC in a region of parameter space that satisfies existing collider constraints. We also present the reach of the LHC at 13 TeV in constraining the relevant region of parameter space. Additionally we show that within the same framework a suitably chosen fermion charged only under the exotic Abelian group can, in the region of parameter space preferred by the $\bar{t}th$ measurements, simultaneously explain the dark matter relic density and the $\gamma$-ray excess at the galactic center observed by the Fermi-LAT experiment.

    hep-phJHEP(2016)·28 citations
11. 11*

    A constrained supersymmetric left-right model

    Martin Hirsch🇪🇸 · Manuel E. Krauss🇩🇪 · Toby Opferkuch🇩🇪 · Werner Porod🇩🇪 · Florian Staub🇨🇭

    We present a supersymmetric left-right model which predicts gauge coupling unification close to the string scale and extra vector bosons at the TeV scale. The subtleties in constructing a model which is in agreement with the measured quark masses and mixing for such a low left-right breaking scale are discussed. It is shown that in the constrained version of this model radiative breaking of the gauge symmetries is possible and a SM-like Higgs is obtained. Additional CP-even scalars of a similar mass or even much lighter are possible. The expected mass hierarchies for the supersymmetric states differ clearly from those of the constrained MSSM. In particular, the lightest down-type squark, which is a mixture of the sbottom and extra vector-like states, is always lighter than the stop. We also comment on the model's capability to explain current anomalies observed at the LHC.

    hep-phJHEP(2016)·13 citations
12. 12*

    Mono-W Dark Matter Signals at the LHC: Simplified Model Analysis

    Nicole F. Bell🇦🇺 · Yi Cai🇦🇺 · Rebecca K. Leane🇦🇺

    We study mono-W signals of dark matter (DM) production at the LHC, in the context of gauge invariant renormalizable models. We analyze two simplified models, one involving an s-channel Z' mediator and the other a t-channel colored scalar mediator, and consider examples in which the DM-quark couplings are either isospin conserving or isospin violating after electroweak symmetry breaking. While previous work on mono-W signals have focused on isospin violating EFTs, obtaining very strong limits, we find that isospin violating effects are small once such physics is embedded into a gauge invariant simplified model. We thus find that the 8 TeV mono-W results are much less constraining than those arising from mono-jet searches. Considering both the leptonic (mono-lepton) and hadronic (mono fat jet) decays of the W, we determine the 14 TeV LHC reach of the mono-W searches with 3000 fb${}^{-1}$ of data. While a mono-W signal would provide an important complement to a mono-jet discovery channel, existing constraints on these models imply it will be a challenging signal to observe at the 14 TeV LHC.

    hep-phhep-exJCAP(2016)·66 citations
13. 13*

    Jet shapes for boosted jet two-prong decays from first-principles

    Mrinal Dasgupta🇬🇧 · Lais Schunk🇫🇷 · Gregory Soyez🇫🇷

    Several boosted jet techniques use jet shape variables to discriminate the multi-pronged signal from Quantum Chromodynamics backgrounds. In this paper, we provide a first-principles study of an important class of jet shapes all of which put a constraint on the subjet mass: the mass-drop parameter (${\mu }^2$), the $N$-subjettiness ratio (${\tau }_{21}^{(\beta =2)}$) and energy correlation functions ($C_2^{(\beta =2)}$ or $D_2^{(\beta =2)}$). We provide analytic results both for QCD background jets as well as for signal processes. We further study the situation where cuts on these variables are applied recursively with Cambridge-Aachen de-clustering of the original jet. We also explore the effect of the choice of axis for $N$-subjettiness and jet de-clustering. Our results bring substantial new insight into the nature, gain and relative performance of each of these methods, which we expect will influence their future application for boosted object searches.

    hep-phhep-exJHEP(2016)·41 citations
14. 14*

    Short-distance QCD corrections to $K^0{\bar{K}}^0$ mixing at next-to-leading order in Left-Right models

    Véronique Bernard🇫🇷 · Sébastien Descotes-Genon🇫🇷 · Luiz Vale Silva🇫🇷

    Left-Right (LR) models are extensions of the Standard Model where left-right symmetry is restored at high energies, and which are strongly constrained by kaon mixing described in the framework of the $|\Delta S|=2$ effective Hamiltonian. We consider the short-distance QCD corrections to this Hamiltonian both in the Standard Model (SM) and in LR models. The leading logarithms occurring in these short-distance corrections can be resummed within a rigourous Effective Field Theory (EFT) approach integrating out heavy degrees of freedom progressively, or using an approximate simpler method of regions identifying the ranges of loop momentum generating large logarithms in the relevant two-loop diagrams. We compare the two approaches in the SM at next-to-leading order, finding a very good agreement when one scale dominates the problem, but only a fair agreement in the presence of a large logarithm at leading order. We compute the short-distance QCD corrections for LR models at next-to-leading order using the method of regions, and we compare the results with the EFT approach for the $W{W}^{\prime }$ box with two charm quarks (together with additional diagrams forming a gauge-invariant combination), where a large logarithm occurs already at leading order. We conclude by providing next-to-leading-order estimates for $cc$, $ct$ and $tt$ boxes in LR models.

    hep-phJHEP(2016)·14 citations
15. 15*

    SO(10) grand unification in light of recent LHC searches and colored scalars at the TeV-scale

    Ufuk Aydemir🇸🇪

    We analyze the compatibility of the recent LHC signals and the TeV-scale left-right model(s) in the minimal nonsupersymmetric $SO(10)$ framework. We show that the models in which the Higgs content is selected based on the extended survival hypothesis do not allow the $W_R$ boson to be at the TeV-scale. By relaxing this conjecture, we investigate various scenarios where a number of colored-scalars, originated from various Pati-Salam multiplets, are light and whence they survive down to the low energies. Performing a detailed renormalization group analysis with various low-energy Higgs configurations and symmetry breaking chains, while keeping the high energy Higgs content unmodified; we find that, among a number of possibilities, the models which have a light color-triplet scalar, and its combination with a light color-sextet, particularly stand out. Although these models do allow a TeV-scale $W_R$ boson, generating the required value of the gauge coupling $g_R$ at this scale is non-trivial.

    hep-phInt.J.Mod.Phys.A(2016)·18 citations
16. 16*

    QED corrections to the Altarelli-Parisi splitting functions

    Daniel de Florian🇦🇷 · German F. R. Sborlini🇪🇸 · German Rodrigo🇪🇸

    We discuss the combined effect of QED and QCD corrections to the evolution of parton distributions. We extend the available knowledge of the Altarelli-Parisi splitting functions to one order higher in QED, and provide explicit expressions for the splitting kernels up to $\mathcal{O}(\alpha {\alpha }_{\mathrm{S}})$. The results presented in this article allow to perform a parton distribution function analysis reaching full NLO QCD-QED combined precision.

    hep-phEPJC(2016)·96 citations
17. 17*

    Effects of the FCNC couplings in production of new heavy quarks within Z' models at the LHC

    V. Cetinkaya🇹🇷 · V. Ari · O. Cakir

    We study the flavor changing neutral current couplings of new heavy quarks through the Z' models at the LHC. We calculate the cross sections for the signal and the corresponding standard model background processes. Considering the present limits on the mass of new heavy quarks and the Z' boson, we performed an analysis to investigate the parameter space (mixing and mass) through different Z' models. For an FCNC mixing parameter x=0.1 and the Z' mass M_{Z'}=2000 GeV, and new heavy quark mass m_{t'}=700 GeV at the LHC with \sqrt{s}=13 TeV, we find the cross section for single production of new heavy quarks associated with top quarks as 5.8 fb, 3.3 fb, 1.5 fb and 1.2 fb within the Z'_{\eta} , Z'_{\psi} , Z'_{LP} and Z'_{\chi} models, respectively. It is shown that the sensitivity would benefit from the flavor tagging.

    hep-phAdv.High Energy Phys.(2016)·0 citations
18. 18*

    Understanding the Masses and Mixings of One-Zero Textures in 3+1 Scenario

    Newton Nath🇮🇳 · Monojit Ghosh🇮🇳 · Shivani Gupta🇦🇺

    We present a detailed analysis and phenomenological consequences of neutrino mass matrix, $M_{\nu }$, with one-zero texture in the flavor basis where the active neutrino sector is extended by one sterile neutrino (3+1 case). In particular, our aim is to explore behaviour of the sterile mixing parameters in detail when one of the elements of the neutrino mass matrix goes to zero. To study this, we consider two distinct mass spectrum of the active neutrinos: (i) completely hierarchical mass spectrum with a vanishing neutrino mass and (ii) completely quasidegenerate mass spectrum. In 3+1 scenario, the low energy neutrino mass matrix, $M_{\nu }$, is a $4\times 4$ matrix and has 10 independent elements. Thus it can have 10 possible one-zero textures. From the earlier studies it can be inferred that, if one assumes one vanishing neutrino mass, then only seven of these $M_{\nu }$ are phenomenologically allowed by the current neutrino oscillation data. On the other hand, if the neutrinos are quasidegenerate then there are eight phenomenologically viable one-zero textures. In this present work, we study the correlations between the sterile mixing parameters for each of these allowed textures for both mass spectrum and also their implications on the effective Majorana mass.

    hep-phInt.J.Mod.Phys.A(2016)·16 citations
19. 19*

    Probing vacuum birefringence under a high-intensity laser field with gamma-ray polarimetry at the GeV scale

    Yoshihide Nakamiya · Kensuke Homma

    Probing vacuum structures deformed by high intense fields is of great interest in general. In the context of quantum electrodynamics (QED), the vacuum exposed by a linearly polarized high-intensity laser field is expected to show birefringence. We consider the combination of a 10 PW laser system to pump the vacuum and 1 GeV photons to probe the birefringent effect. The vacuum birefringence can be measured via the polarization flip of the probe $\gamma$-rays which can also be interpreted as phase retardation of probe photons. We provide theoretically how to extract phase retardation of GeV probe photons via pair-wise topology of the Bethe-Heitler process in a polarimeter and then evaluate the measurability of the vacuum birefringence via phase retardation given a concrete polarimeter design with a realistic set of laser parameters and achievable pulse statistics.

    hep-phhep-exphysics.ins-detPRD(2017)·58 citations
20. 20*

    Standard Model Theory for Collider Physics

    M. Grazzini🇨🇭

    I briefly review the current theoretical description of Standard Model processes relevant for the LHC, and the tools that are used in the corresponding phenomenological applications. I discuss in particular the recent theoretical progress in NLO and NNLO QCD calculations, electroweak corrections, resummations, Monte Carlo tools and parton distribution functions.

    hep-phhep-exPoS(2015)·2 citations
21. 21*

    Photon dissociation into two and three jets: initial and final state corrections

    R. Boussarie🇫🇷 · A. Grabovsky🇷🇺 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷

    We study the impact factor for the photon to quark, antiquark and gluon transition within Balitsky's shock-wave formalism. Our aim is to extend existing results beyond approximations discussed in the literature. We present our results of the real contribution, and present some intermediate results on virtual contributions for the photon to quark, antiquark transition.

    hep-phActa Phys.Polon.Supp.(2015)·3 citations
22. 22*

    Detecting the disruption of dark-matter halos with stellar streams

    Jo Bovy🇨🇦

    Narrow stellar streams in the Milky Way halo are uniquely sensitive to dark-matter subhalos, but many of these subhalos may be tidally disrupted. I calculate the interaction between stellar and dark-matter streams using analytical and $N$-body calculations, showing that disrupting objects can be detected as low-concentration subhalos. Through this effect, we can constrain the lumpiness of the halo as well as the orbit and present position of individual dark-matter streams. This will have profound implications for the formation of halos and for direct and indirect-detection dark-matter searches.

    ↳ astro-ph.GAastro-ph.COhep-phPRL(2016)·38 citations
23. 23*

    Interaction between bosonic dark matter and stars

    Richard Brito🇵🇹 · Vitor Cardoso🇵🇹 · Caio F. B. Macedo🇵🇹 · Hirotada Okawa🇯🇵 · Carlos Palenzuela🇪🇸

    We provide a detailed analysis of how bosonic dark matter "condensates" interact with compact stars, extending significantly the results of a recent Letter. We focus on bosonic fields with mass $m_B$, such as axions, axion-like candidates and hidden photons. Self-gravitating bosonic fields generically form "breathing" configurations, where both the spacetime geometry and the field oscillate, and can interact and cluster at the center of stars. We construct stellar configurations formed by a perfect fluid and a bosonic condensate, and which may describe the late stages of dark-matter accretion onto stars, in dark matter-rich environments. These composite stars oscillate at a frequency which is a multiple of $f=2.5\times 10^{14}\left(m_B{c}^2/eV\right)\mathrm{Hz}$. Using perturbative analysis and Numerical Relativity techniques, we show that these stars are generically stable, and we provide criteria for instability. Our results also indicate that the growth of the dark matter core is halted close to the Chandrasekhar limit. We thus dispel a myth concerning dark matter accretion by stars: dark mater accretion does not necessarily lead to the destruction of the star, nor to collapse to a black hole. Finally, we argue that stars with long-lived bosonic cores may also develop in other theories with effective mass couplings, such as (massless) scalar-tensor theories.

    ↳ astro-ph.SRgr-qchep-phPRD(2016)·115 citations
24. 24*

    Aharonov-Bohm phases in a quantum LC circuit

    ChunJun Cao🇺🇸 · Yuan Yao🇨🇦 · Ariel R. Zhitnitsky🇨🇦

    We study novel types of contributions to the partition function of the Maxwell system defined on a small compact manifold. These contributions, often not addressed in the perturbative treatment with physical photons, emerge as a result of tunneling transitions between topologically distinct but physically identical vacuum winding states. These new terms give an extra contribution to the Casimir pressure, yet to be measured. We argue that this effect is highly sensitive to a small external electric field, which should be contrasted with the conventional Casimir effect where the vacuum photons are essentially unaffected by any external field. Furthermore, photons will be emitted from the vacuum in response to a time-dependent electric field, similar to the dynamical Casimir effect in which real particles are radiated from the vacuum due to the time-dependent boundary conditions. We also propose an experimental setup using a quantum LC circuit to detect this novel effect. We expect physical electric charges to appear on the capacitor plates when the system dimension is such that coherent Aharonov-Bohm phases can be maintained over macroscopically large distances.

    ↳ hep-thcond-mat.str-elhep-phquant-phPRD(2016)·7 citations
25. 25*

    Dynamical Axion Field in a Magnetic Topological Insulator Superlattice

    Jing Wang🇺🇸 · Biao Lian🇺🇸 · Shou-Cheng Zhang🇺🇸

    We propose that the dynamical axion field can be realized in a magnetic topological insulator superlattice or a topological paramagnetic insulator. The magnetic fluctuations of these systems produce a pseudoscalar field which has an axionic coupling to the electromagnetic field, and thus it gives a condensed-matter realization of the axion electrodynamics. Compared to the previously proposed dynamical axion materials where a long range antiferromagnetic order is required, the systems proposed here have the advantage that only a uniform magnetization or a paramagnetic state is needed for the dynamic axion. We further propose several experiments to detect such a dynamical axion field.

    ↳ cond-mat.mes-hallhep-phPRB(2016)·40 citations
26. 26*

    Cosmology with orthogonal nilpotent superfields

    Sergio Ferrara🇨🇭 · Renata Kallosh🇺🇸 · Jesse Thaler🇺🇸

    We study the application of a supersymmetric model with two constrained supermultiplets to inflationary cosmology. The first superfield S is a stabilizer chiral superfield satisfying a nilpotency condition of degree 2, S^2=0. The second superfield Phi is the inflaton chiral superfield, which can be combined into a real superfield B=(Phi-Phi*)/2i. The real superfield B is orthogonal to S, S B=0, and satisfies a nilpotency condition of degree 3, B^3=0. We show that these constraints remove from the spectrum the complex scalar sgoldstino, the real scalar inflaton partner (i.e. the "sinflaton"), and the fermionic inflatino. The corresponding supergravity model with de Sitter vacua describes a graviton, a massive gravitino, and one real scalar inflaton, with both the goldstino and inflatino being absent in unitary gauge. We also discuss relaxed superfield constraints where S^2=0 and S Phi* is chiral, which removes the sgoldstino and inflatino, but leaves the sinflaton in the spectrum. The cosmological model building in both of these inflatino-less models offers some advantages over existing constructions.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2016)·72 citations
27. 27*

    Inflatino-less Cosmology

    John Joseph M. Carrasco🇫🇷 · Renata Kallosh🇺🇸 · Andrei Linde🇺🇸

    We construct inflationary models in the context of supergravity with orthogonal nilpotent superfields [1]. When local supersymmetry is gauge-fixed in the unitary gauge, these models describe theories with only a single real scalar (the inflaton), a graviton and a gravitino. Critically, there is no inflatino, no sgoldstino, and no sinflaton in these models. This dramatically simplifies cosmological models which can simultaneously describe inflation, dark energy and SUSY breaking.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2016)·66 citations
28. 28*

    Extrapolation Technique Pitfalls in Asymmetry Measurements at Colliders

    Katrina Colletti🇺🇸 · Ziqing Hong🇺🇸 · David Toback🇺🇸 · Jonathan S. Wilson🇺🇸

    Asymmetry measurements are common in collider experiments and can sensitively probe particle properties. Typically, data can only be measured in a finite region covered by the detector, so an extrapolation from the visible asymmetry to the inclusive asymmetry is necessary. Often a constant multiplicative factor is more than adequate for the extrapolation and this factor can be readily determined using simulation methods. However, there is a potential, avoidable pitfall involved in the determination of this factor when the asymmetry in the simulated data sample is small. We find that to obtain a reliable estimate of the extrapolation factor, the number of simulated events required rises as the inverse square of the simulated asymmetry; this can mean that an unexpectedly large sample size is required when determining its value.

    ↳ hep-exhep-phNucl.Instrum.Meth.A(2016)·0 citations
29. 29*

    Neutron and proton electric dipole moments from $N_f=2+1$ domain-wall fermion lattice QCD

    Eigo Shintani🇯🇵 · Thomas Blum🇺🇸 · Taku Izubuchi🇺🇸 · Amarjit Soni🇺🇸

    We present a lattice calculation of the neutron and proton electric dipole moments (EDM's) with $N_f=2+1$ flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the $\theta$ vacuum of QCD. In this computation, we use pion masses 0.33 and 0.42 GeV and 2.7 fm${}^3$ lattices with Iwasaki gauge action and a 0.17 GeV pion and 4.6 fm${}^3$ lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode-averaging technique enables an efficient and high statistics calculation. Chiral behavior of lattice EDM's is discussed in the context of baryon chiral perturbation theory. In addition, we also show numerical evidence on relationship of three- and two-point correlation function with local topological distribution.

    ↳ hep-lathep-phnucl-thPRD(2016)·51 citations
30. 30*

    Inelastic dark matter with spin-dependent couplings to protons and large modulation fractions in DAMA

    Stefano Scopel🇰🇷 · KookHyun Yoon (Sogang Univ.)🇰🇷

    We discuss a scenario where the DAMA modulation effect is explained by a Weakly Interacting Massive Particle (WIMP) which upscatters inelastically to a heavier state and predominantly couples to the spin of protons. In this scenario constraints from xenon and germanium targets are evaded dynamically, due to the suppression of the WIMP coupling to neutrons, while those from fluorine targets are evaded kinematically, because the minimal WIMP incoming speed required to trigger upscatters off fluorine exceeds the maximal WIMP velocity in the Galaxy, or is very close to it. In this scenario WIMP scatterings off sodium are usually sensitive to the large-speed tail of the WIMP velocity distribution and modulated fractions of the signal close to unity arise in a natural way. On the other hand, a halo-independent analysis with more conservative assumptions about the WIMP velocity distribution allows to extend the viable parameter space to configurations where large modulated fractions are not strictly necessary. We discuss large modulated fractions in the Maxwellian case showing that they imply a departure from the usual cosine time dependence of the expected signal in DAMA. However we explicitly show that the DAMA data is not sensitive to this distortion, both in time and frequency space, even in the extreme case of a 100 % modulated fraction. Moreover the same scenario provides an explanation of the maximum in the energy spectrum of the modulation amplitude detected by DAMA in terms of WIMPs whose minimal incoming speed matches the kinematic threshold for inelastic upscatters. For the elastic case the detection of such maximum suggests an inversion of the modulation phase below the present DAMA energy threshold, while this is not expected for inelastic scattering. This may allow to discriminate between the two scenarios in a future low-threshold analysis of the DAMA data.

    ↳ astro-ph.COhep-phJCAP(2016)·18 citations
31. 31*

    Wave Propagation in Modified Gravity

    Jan Ø. Lindroos🇳🇴 · Claudio Llinares🇳🇴 · David F. Mota🇳🇴

    We investigate the propagation of scalar waves induced by matter sources in the context of scalar-tensor theories of gravity which include screening mechanisms for the scalar degree of freedom. The usual approach when studying these theories in the non-linear regime of cosmological perturbations is based on the assumption that scalar waves travel at the speed of light. Within General Relativity such approximation is good and leads to no loss of accuracy in the estimation of observables. We find, however, that mass terms and non-linearities in the equations of motion lead to propagation and dispersion velocities significantly different from the speed of light. As the group velocity is the one associated to the propagation of signals, a reduction of its value has direct impact on the behavior and dynamics of nonlinear structures within modified gravity theories with screening. For instance, the internal dynamics of galaxies and satellites submerged in large dark matter halos could be affected by the fact that the group velocity is smaller than the speed of light. It is therefore important, within such framework, to take into account the fact that different part of a galaxy will see changes in the environment at different times. A full non-static analysis may be necessary under those conditions.

    ↳ gr-qcastro-ph.COhep-phPRD(2016)·7 citations
32. 32*

    Improving Constraints on Proton Structure using CMS measurements

    Saranya Ghosh (for the CMS Collaboration)🇮🇳

    Production of electroweak bosons, heavy quarks and jets in proton-proton collisions probe different aspects of QCD and are sensitive to the details of proton structure, expressed by parton distribution functions (PDFs). Precise measurements of cross sections of these processes are used by the CMS experiment to demonstrate the impact of the LHC data on the PDFs and their precision. The measurements of muon charge asymmetry in W-boson production at a center-of-mass of 7 and 8 TeV is used to improve the constraints on the valence-quark distributions, while the associated production of W-boson and charm quark provides information on the s-quark distribution in the proton. Production of inclusive jets, as measured by CMS at center-of-mass energy of 7 TeV, provides important constraints on the gluon distribution.

    ↳ hep-exhep-phPoS(2015)·0 citations
33. 33*

    Antimatter ${}_{\Lambda }^4$H Hypernucleus Production and the ${}_{\Lambda }^3$H/${}^3$He Puzzle in Relativistic Heavy-Ion Collisions

    Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳

    We show that the measured yield ratio ${}_{\Lambda }^3$H/${}^3$He (${}_{\overline{\Lambda }}^3\overline{\text{H}}$/${}^3\overline{\text{He}}$) in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV and in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV can be understood within a covariant coalescence model if (anti-)$\Lambda$ particles freeze out earlier than (anti-)nucleons but their relative freezeout time is closer at $\sqrt{s_{NN}}=2.76$ TeV than at $\sqrt{s_{NN}}=200$ GeV. The earlier (anti-)$\Lambda$ freezeout can significantly enhance the yield of (anti)hypernucleus ${}_{\Lambda }^4$H (${}_{\overline{\Lambda }}^4\overline{\text{H}}$), leading to that ${}_{\overline{\Lambda }}^4\overline{\text{H}}$ has a comparable abundance with ${}^4\overline{\text{He}}$ and thus provides an easily measured antimatter candidate heavier than ${}^4\overline{\text{He}}$. The future measurement on ${}_{\Lambda }^4$H (${}_{\overline{\Lambda }}^4\overline{\text{H}}$) would be very useful to understand the (anti-)$\Lambda$ freezeout dynamics and the production mechanism of (anti)hypernuclei in relativistic heavy-ion collisions.

    ↳ nucl-thastro-ph.COhep-phnucl-exPRC(2016)·31 citations
34. 34*

    Dark Matter Searches with H.E.S.S

    Knut Morå (for the H.E.S.S collaboration) (OKC, SU)🇸🇪

    Cosmological measurements indicate that a large component of non-visible gravitating matter is present in the universe. A common hypothesis for its origin is a weakly interacting, massive particle. Annihilations or decays of such particles could produce gamma rays. The H.E.S.S. experiment is an imaging air Cherenkov telescope array located in Namibia which may detect very high energy gamma-rays between 300 GeV and 10 TeV. This talk will present an overview of two recent H.E.S.S. searches for dark matter in the very high energy region, one targeting dwarf galaxies, the other one a cored dark matter profile at the galactic center.

    ↳ astro-ph.HEhep-ph9 citations
35. 35*

    Inflationary Magnetogenesis with Broken Local U(1) Symmetry

    Guillem Domènech🇯🇵 · Chunshan Lin🇯🇵 · Misao Sasaki🇯🇵

    We point out that a successful inflationary magnetogenesis could be realised if we break the local U(1) gauge symmetry during inflation. The effective electric charge is fixed as a fundamental constant, which allows us to obtain an almost scale invariant magnetic spectrum avoiding both the strong coupling and back reaction problems. We examine the corrections to the primordial curvature perturbation due to these stochastic electromagnetic fields and find that, at both linear and non-linear orders, the contributions from the electromagnetic field are negligible compared to those created from vacuum fluctuations. Finally, the U(1) gauge symmetry is restored at the end of inflation.

    ↳ astro-ph.COgr-qchep-phEPL(2016)·21 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.