Thu·Apr 7, 2016Thursday·April 7, 2016

1. 01*

   Tensor integrand reduction via Laurent expansion

   Valentin Hirschi🇺🇸 · Tiziano Peraro🇬🇧

   We introduce a new method for the application of one-loop integrand reduction via the Laurent expansion algorithm, as implemented in the public C++ library Ninja. We show how the coefficients of the Laurent expansion can be computed by suitable contractions of the loop numerator tensor with cut-dependent projectors, making it possible to interface Ninja to any one-loop matrix element generator that can provide the components of this tensor. We implemented this technique in the Ninja library and interfaced it to MadLoop, which is part of the public MadGraph5_aMC@NLO framework. We performed a detailed performance study, comparing against other public reduction tools, namely CutTools, Samurai, IREGI, PJFry++ and Golem. We find that Ninja outperforms traditional integrand reduction in both speed and numerical stability, the latter being on par with that of the tensor integral reduction tool Golem which is however more limited and slower than Ninja. We considered many benchmark multi-scale processes of increasing complexity, involving QCD and electro-weak corrections as well as effective non-renormalizable couplings, showing that Ninja's performance scales well with both the rank and multiplicity of the considered process.

   hep-phJHEP(2016)·56 citations
2. 02*

   Lepton Number Violation and `Diracness' of massive neutrinos composed of Majorana states

   Janusz Gluza🇵🇱 · Tomasz Jelinski🇵🇱 · Robert Szafron🇨🇦

   Majorana neutrinos naturally lead to a Lepton Number Violation (LNV). A superposition of Majorana states can mimic Dirac-type neutrinos, leading to its conservation (LNC). We demonstrate on the example of specific observables related to high and low energy processes how a strength of LNV correlates with neutrino parameters such as CP-phases, flavor mixings, mass ratios. We stress the coaction between low and high energy studies for putting phenomenological models to a quantitative test. Secondly, we conclude that in order to fully study the role of heavy neutrinos in search for New Physics (NP) signals, a departure from trivial scenarios assuming degeneracy in mass and no flavor mixing or CP-phases becomes necessary for a proper physical analysis.

   hep-phPRD(2016)·71 citations
3. 03*

   Bootstrapping rapidity anomalous dimension for transverse-momentum resummation

   Ye Li🇺🇸 · Hua Xing Zhu🇺🇸

   Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.

   hep-phhep-thPRL(2017)·262 citations
4. 04*

   Suppressing supersymmetric flavor violations through quenched gaugino-flavor interactions

   James D. Wells🇺🇸 · Yue Zhao🇺🇸

   Realizing that couplings related by supersymmetry (SUSY) can be disentangled when SUSY is broken, it is suggested that unwanted flavor and CP violating SUSY couplings may be suppressed via quenched gaugino-flavor interactions, which may be accomplished by power-law running of sfermion anomalous dimensions. A simple theoretical framework to accomplish this is exemplified and the defeated constraints are tallied. One key implication of the scenario is the expectation of enhanced top, bottom and tau production at the LHC, accompanied by large missing energy. Also, direct detection signals of dark matter may be more challenging to find than in conventional SUSY scenarios.

   hep-phPRD(2017)·0 citations
5. 05*

   Anatomy of Exotic Higgs Decays in 2HDM

   Felix Kling🇺🇸 · Jose Miguel No🇬🇧 · Shufang Su🇺🇸

   Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. We provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2.

   hep-phJHEP(2016)·90 citations
6. 06*

   Impact of Future Lepton Flavor Violation Measurements in the Minimal Supersymmetric Standard Model

   Sebastian A. R. Ellis🇺🇸 · Aaron Pierce🇺🇸

   Working within the context of the minimal supersymmetric standard model, we compare current bounds from quark flavor changing processes with current and upcoming bounds on lepton flavor violation. We assume supersymmetry breaking approximately respects CP invariance. Under the further assumption that flavor violating insertions in the quark and lepton scalar masses are comparable, we explore when lepton flavor violation provides the strongest probe of new physics. We quote results both for spectra with all superpartners near the TeV scale and where scalars are multi-TeV. Constraints from quark flavor changing neutral currents are in many cases already stronger than those expected from future lepton flavor violation bounds, but large regions of parameter space remain where the latter could provide a discovery mode for supersymmetry.

   hep-phPRD(2016)·12 citations
7. 07*

   Inclusive production of X$\to b\bar{b}$ plus a recoil for the LHC Run-II

   Nicolas Gutierrez🇬🇧

   This letter presents a study of the inclusive production of X$\to b\bar{b}$ plus a recoil, using simulated samples of $pp$ collisions at $\sqrt{s}=14$ TeV for an integrated luminosity in the range between 30 fb${}^{-1}$ to 3 ab${}^{-1}$. The case for experiments to include un-prescaled $b$-tag multijet triggers for this topology is made and the ideal jet thresholds are discussed. The sensitivity to Standard Model Higgs with a transverse momentum of at least 200 GeV is evaluated with respect to a continuous background, dominated by multijet processes. The mass of $b$-jet-pairs is analysed, quoting sensitivity to cross-sections in the range of 1 to 2 pb, for 100 fb${}^{-1}$, covering the Higgs production cross section of 1.8 pb. The trigger strategy presented in this letter is compared to triggers already in use, showing an increase on the signal efficiency for masses below 200 GeV and a performance comparable to a logic OR of all the currently available akin triggers for higher masses. The robustness of the expected sensitivity against systematic uncertainties is estimated by considering various typical sources, such as those on the fitting parameters of the continuous background, shape uncertainties affecting the signal acceptance and the background modelling. The accuracy of a Higgs production cross section measurements is also discussed, quoting sensitivity to deviations of 50% for 100 fb${}^{-1}$ and 10% for 3 ab${}^{-1}$.

   hep-phEPL(2016)·0 citations
8. 08*

   Evolving images of the proton: Hadron physics over the past 40 years

   Michael R. Pennington🇺🇸

   Once upon a time, the world was simple: the proton contained three quarks, two {\it ups} and a {\it down}. How these give the proton its mass and its spin seemed obvious. Over the past forty years the proton has become more complicated, and how even these most obvious of its properties is explained in a universe of quarks, antiquarks and gluons remains a challenge. That this should be so should come as no surprise. Quantum Chromodynamics, the theory of the strong interaction, is seemingly simple, and its consequences are straightforward in the domain of hard scattering where perturbation theory applies. However, the beauty of the hadron world is its diversity. The existence of hadrons, their properties, and their binding into nuclei do not appear in the Lagrangian of QCD. They all emerge as a result of its strong coupling. Strong coupling QCD creates complex phenomena, much richer than known 40 years ago: a richness that ensures colour confinement and accounts for more than 95\% of the mass of the visible Universe. How strong coupling QCD really works requires a synergy between experiment and theory. A very personal view of these fascinating developments in cold QCD is presented.

   hep-phhep-exnucl-exnucl-thJ.Phys.G(2016)·13 citations
9. 09*

   Trilinear gauge boson couplings in the gauge-Higgs unification

   Yuki Adachi🇯🇵 · Nobuhito Maru🇯🇵

   We examine trilinear gauge boson couplings (TGCs) in the context of the $SU(3{)}_W\otimes U(1{)}^{\prime }$ gauge-Higgs unification scenario. The TGCs play important roles in the probes of the physics beyond the standard model, since they are highly restricted by the experiments. We discuss mass spectrum of the neutral gauge boson with brane-localized mass terms carefully and find that the TGCs and $\rho$ parameter may deviate from standard model predictions. Finally we put a constraint from these observables and discuss the possible parameter space.

   hep-phPTEP(2016)·7 citations
10. 10*

    Role of $Y(4630)$ in the $p\bar{p}\to {\Lambda }_c{\bar{\Lambda }}_c$ reaction near threshold

    Yan-Yan Wang🇨🇳 · Qi-Fang Lü🇨🇳 · En Wang🇨🇳 · De-Min li🇨🇳

    We investigate the charmed baryon production reaction $p\bar{p}\to {\Lambda }_c{\bar{\Lambda }}_c$ in an effective Lagrangian approach. Besides the $t$-channel $D^0$ and $D^{\ast 0}$ mesons exchanges, the $s$-channel $Y(4630)$ meson exchange is taken into account. For the total cross sections, the $D^0$ and $D^{\ast 0}$ mesons provide minor background contributions, while the $Y(4630)$ state gives a clear peak structure with the magnitude of 10 $\mu$b at center of mass energy 4.63 GeV. Basing on the results, we suggest that the reaction of $p\bar{p}\to {\Lambda }_c{\bar{\Lambda }}_c$ can be used to search for the $1^{--}$ charmonium-like $Y(4630)$ state, and our predictions can be tested in future by the $\bar{\mathrm{P}}\mathrm{ANDA}$ facility.

    hep-phnucl-thPRD(2016)·17 citations
11. 11*

    Large-$N_c$ pole trajectories of the vector kaon $K^{\ast }(892)$ and of the scalar kaons $K_0^{\ast }(800)$ and $K_0^{\ast }(1430)$

    Milena Soltysiak🇵🇱 · Thomas Wolkanowski🇩🇪 · Francesco Giacosa🇩🇪

    We study the spectral functions, the poles and their trajectories for increasing $N_c$ of the vector kaon state $K^{\ast }(892),$ characterized by $I(J^P)=\frac{1}{2}(1^{-})$, and of the scalar kaons $K_0^{\ast }(800)$ and $K_0^{\ast }(1430),$ characterized by $I(J^P)=\frac{1}{2}(0^{+})$. To this end, we use relativistic QFT's Lagrangians with both derivative and non-derivative terms. In the vector kaonic sector the spectral function is well approximated by a Breit-Wigner function: there is one single peak and, correspondingly, a single pole in the complex plane. On the contrary, in the scalar sector, although the Lagrangian contains only one scalar kaonic field, we find two poles, one corresponding to a standard quark-antiquark ,,seed\textquotedblright\ state $K_0^{\ast }(1430),$ and one to a \textquotedblleft companion\textquotedblright\ dynamically generate pole $K_0^{\ast }(800)$. The latter does not correspond to any peak in the scalar kaonic spectral function, but only to an enhancement in the low-energy regime.

    hep-phActa Phys.Polon.Supp.(2016)·3 citations
12. 12*

    Dynamical corrections to the anomalous holographic softwall model: the pomeron and the odderon

    Eduardo Folco Capossoli🇧🇷 · Danning Li🇨🇳 · Henrique Boschi-Filho🇧🇷

    In this work we use the holographic softwall AdS/QCD model with anomalous dimension contributions coming from two different QCD beta functions to calculate the masses of higher spin glueball states for both even and odd spins and its respective Regge trajectories, related to the pomeron and the odderon, respectively. We further investigate this model taking into account dynamical corrections due to a dilaton potential consistent with Einstein equations in 5 dimensions. The results found in this work for the Regge trajectories within the anomalous softwall model with dynamical corrections are consistent with those presented in the literature.

    hep-phhep-thEPJC(2016)·39 citations
13. 13*

    The sensitivity of the Higgs boson branching ratios to the W boson width

    William Murray🇬🇧

    The Higgs boson branching ratio into vector bosons is sensitive to the decay widths of those vector bosons because they are produced with at least one boson significantly off-shell. Gamma(H to V V ) is approximately proportional to the product of the Higgs boson coupling and the vector boson width. Gamma Z is well known, but Gamma W gives an uncertainty on Gamma(H to W W ) which is not negligible. The ratio of branching ratios, BR(H to W W )/BR(H to ZZ) measured by a combination of ATLAS and CMS at LHC is used herein to extract a width for the W boson of Gamma W = 1.8+0.4-0.3 GeV by assuming Standard Model couplings of the Higgs bosons. This dependence of the branching ratio on Gamma W is not discussed in most Higgs boson coupling analyses.

    hep-phPLB(2016)·1 citation
14. 14*

    Contributions of loops with dynamical vector mesons to masses and decay constants of pseudoscalar mesons and their quark mass dependence

    Carla Terschlüsen🇸🇪 · Stefan Leupold (Uppsala University)🇸🇪

    The contributions of one-loop diagrams with dynamical vector mesons to masses and decay constants of pseudoscalar mesons are determined. Hereby, a relativistic Lagrangian for both the pseudoscalar-meson octet and the vector-meson nonet is used. The vector mesons are given in the antisymmetric tensor representation. Both the differences between static and dynamical vector mesons and the differences between calculations with and without vector mesons are studied as functions of the light quark mass.

    hep-ph4 citations
15. 15*

    The ground state of the Pomeron and its decays to light mesons and photons

    A.A. Godizov🇷🇺

    The problem of the timelike Pomeron coupling to light mesons and photons is considered in light of available data on high-energy meson-proton scattering. Possible correspondence of $f_2(1950)$ resonance to the ground state of the Pomeron is argued.

    hep-phhep-exEPJC(2016)·17 citations
16. 16*

    Quantum Monte Carlo calculations of two neutrons in finite volume

    P. Klos🇩🇪 · J. E. Lynn🇩🇪 · I. Tews🇺🇸 · S. Gandolfi🇺🇸 · A. Gezerlis🇨🇦 · H.-W. Hammer🇩🇪 · M. Hoferichter🇺🇸 · A. Schwenk🇩🇪

    Ab initio calculations provide direct access to the properties of pure neutron systems that are challenging to study experimentally. In addition to their importance for fundamental physics, their properties are required as input for effective field theories of the strong interaction. In this work, we perform auxiliary-field diffusion Monte Carlo calculations of the ground and first excited state of two neutrons in a finite box, considering a simple contact potential as well as chiral effective field theory interactions. We compare the results against exact diagonalizations and present a detailed analysis of the finite-volume effects, whose understanding is crucial for determining observables from the calculated energies. Using the Lüscher formula, we extract the low-energy S-wave scattering parameters from ground- and excited-state energies for different box sizes.

    ↳ nucl-thhep-lathep-phPRC(2016)·26 citations
17. 17*

    Investigating the Uniformity of the Excess Gamma rays towards the Galactic Center Region

    Shunsaku Horiuchi🇺🇸 · Manoj Kaplinghat🇺🇸 · Anna Kwa🇺🇸

    We perform a composite likelihood analysis of subdivided regions within the central $26^{\circ }\times 20^{\circ }$ of the Milky Way, with the aim of characterizing the spectrum of the gamma-ray galactic center excess in regions of varying galactocentric distance. Outside of the innermost few degrees, we find that the radial profile of the excess is background-model dependent and poorly constrained. The spectrum of the excess emission is observed to extend upwards of 10 GeV outside $\sim 5^{\circ }$ in radius, but cuts off steeply between 10--20 GeV only in the innermost few degrees. If interpreted as a real feature of the excess, this radial variation in the spectrum has important implications for both astrophysical and dark matter interpretations of the galactic center excess. Single-component dark matter annihilation models face challenges in reproducing this variation; on the other hand, a population of unresolved millisecond pulsars contributing both prompt and secondary inverse Compton emission may be able to explain the spectrum as well as its spatial dependency. We show that the expected differences in the photon-count distributions of a smooth dark matter annihilation signal and an unresolved point source population are an order of magnitude smaller than the fluctuations in residuals after fitting the data, which implies that mismodeling is an important systematic effect in point source analyses aimed at resolving the gamma-ray excess.

    ↳ astro-ph.HEastro-ph.COhep-phJCAP(2016)·42 citations
18. 18*

    Updated Kinematic Constraints on a Dark Disk

    Eric David Kramer🇺🇸 · Lisa Randall🇺🇸

    We update the method of the Holmberg & Flynn (2000) study, including an updated model of the Milky Way's interstellar gas, radial velocities, an updated reddening map, and a careful statistical analysis, to bound the allowed surface density and scale height of a dark disk. We pay careful attention to the self-consistency of the model, including the gravitational influence of the dark disk on other disk components, and to the net velocity of the tracer stars. We find that the data set exhibits a non-zero bulk velocity in the vertical direction as well as a displacement from the expected location at the Galactic midplane. If not properly accounted for, these features would bias the bound toward low dark disk mass. We therefore perform our analysis two ways. In the first, traditional method, we subtract the mean velocity and displacement from the tracers' phase space distributions. In the second method, we perform a non-equilibrium version of the HF method to derive a bound on the dark disk parameters for an oscillating tracer distribution. Despite updates in the mass model and reddening map, the traditional method results remain consistent with those of HF2000. The second, non-equilibrium technique, however, allows a surface density as large as $14M_{\odot }{\mathrm{pc}}^{-2}$ (and as small as 0), demonstrating much weaker constraints. For both techniques, the bound on surface density is weaker for larger scale height. In future analyses of Gaia data, it will be important to verify whether the tracer populations are in equilibrium.

    ↳ astro-ph.GAhep-phApJ(2016)·40 citations
19. 19*

    Time-reversal-invariance-violating nucleon-nucleon potential in the 1/N_c expansion

    Daris Samart🇹🇭 · Carlos Schat🇦🇷 · Matthias R. Schindler🇺🇸 · Daniel R. Phillips🇺🇸

    We apply the large-$N_c$ expansion to the time-reversal-invariance-violating (TV) nucleon-nucleon potential. The operator structures contributing to next-to-next-to-leading order in the large-$N_c$ counting are constructed. For the TV and parity-violating case we find a single operator structure at leading order. The TV but parity-conserving potential contains two leading-order terms, which however are suppressed by 1/$N_c$ compared to the parity-violating potential. Comparison with phenomenological potentials, including the chiral EFT potential in the TV parity-violating case, leads to large-$N_c$ scaling relations for TV meson-nucleon and nucleon-nucleon couplings.

    ↳ nucl-thhep-phnucl-exPRC(2016)·19 citations
20. 20*

    Constraints on mixed dark matter from anomalous strong lens systems

    Ayuki Kamada🇺🇸 · Kaiki Taro Inoue🇯🇵 · Tomo Takahashi🇯🇵

    Recently it has been claimed that the warm dark matter (WDM) model cannot at the same time reproduce the observed Lyman-{\alpha} forests in distant quasar spectra and solve the small-scale issues in the cold dark matter (CDM) model. As an alternative candidate, it was shown that the mixed dark matter (MDM) model that consists of WDM and CDM can satisfy the constraint from Lyman-{\alpha} forests and account for the "missing satellite problem" as well as the reported 3.5 keV anomalous X-ray line. We investigate observational constraints on the MDM model using strong gravitational lenses. We first develop a fitting formula for the nonlinear power spectra in the MDM model by performing N-body simulations and estimate the expected perturbations caused by line-of-sight structures in four quadruply lensed quasars that show anomaly in the flux ratios. Our analysis indicates that the MDM model is compatible with the observed anomaly if the mass fraction of the warm component is smaller than 0.47 at the 95% confidence level. The MDM explanation to the anomalous X-ray line and the small-scale issues is still viable even after this constraint is taken into account.

    ↳ astro-ph.COhep-phPRD(2016)·49 citations
21. 21*

    Diphoton resonance at e+e- and photon colliders

    F. Richard🇫🇷

    In this note, I will review the opportunities offered by the hint of a new resonance observed at LHC for future e+e- TeV linear collider (LC) projects. This discussion is mainly influenced by two specific scenarios of physics which assume either a (pseudo-)scalar or a tensor resonance, but these estimates can be used in most scenarios. I envisage either a photon collider, which has a guaranteed signal with the LHC observation, or a standard e+e- collider, more straightforward to implement. After a detailed study of the heavy graviton scenario, I conclude that at a TeV LC, high accuracy measurements, including rare modes, allow to unambiguously establish the origin of this resonance. Also envisaged in some detail is a radion scenario which illustrates the production of a scalar. The role of an LC for precision measurements on Higgs and top couplings is recalled in the context of the Randall Sundrum model.

    ↳ hep-exhep-ph10 citations
22. 22*

    Lorentz symmetry and Very Long Baseline Interferometry

    C. Le Poncin-Lafitte🇫🇷 · A. Hees🇺🇸 · S. lambert🇫🇷

    Lorentz symmetry violations can be described by an effective field theory framework that contains both General Relativity and the Standard Model of particle physics called the Standard-Model extension (SME). Recently, post-fit analysis of Gravity Probe B and binary pulsars lead to an upper limit at the $10^{-4}$ level on the time-time coefficient ${\bar{s}}^{TT}$ of the pure-gravity sector of the minimal SME. In this work, we derive the observable of Very Long Baseline Interferometry (VLBI) in SME and then we implement it into a real data analysis code of geodetic VLBI observations. Analyzing all available observations recorded since 1979, we compare estimates of ${\bar{s}}^{TT}$ and errors obtained with various analysis schemes, including global estimations over several time spans and with various Sun elongation cut-off angles, and with analysis of radio source coordinate time series. We obtain a constraint on ${\bar{s}}^{TT}=(-5\pm 8)\times 10^{-5}$, directly fitted to the observations and improving by a factor 5 previous post-fit analysis estimates.

    ↳ gr-qcastro-ph.EPhep-phPRD(2016)·38 citations
23. 23*

    MSSM-like from $S{U}_5\times D_4$ Models

    R.Ahl Laamara🇲🇦 · M. Miskaoui🇲🇦 · E.H Saidi🇲🇦

    Using finite discrete group characters and symmetry breaking by hyperflux as well as constraints on top- quark family, we study minimal low energy effective theory following from SU${}_5\times D_4$ models embedded in F-theory with non abelian flux. Matter curves spectrum of the models is obtained from SU${}_5\times S_5$ theory with monodromy $S_5$ by performing two breakings; first from symmetric group $S_5$ to $S_4$ subsymmetry; and next to dihedral $D_4$ subgroup. As a consequence, and depending on the ways of decomposing triplets of $S_4$, we end with three types of $D_4$- models. Explicit constructions of these theories are given and a MSSM- like spectrum is derived.

    ↳ hep-thhep-phNPB(2016)·2 citations
24. 24*

    Radial Profile of the 3.55 keV line out to $R_{200}$ in the Perseus Cluster

    Jeroen Franse🇳🇱 · Esra Bulbul🇺🇸 · Adam Foster🇺🇸 · Alexey Boyarsky🇳🇱 · Maxim Markevitch🇺🇸 · Mark Bautz🇺🇸 · Dmytro Iakubovskyi🇺🇦 · Mike Loewenstein🇺🇸 · Michael McDonald🇺🇸 · Eric Miller🇺🇸 · Scott W. Randall🇺🇸 · Oleg Ruchayskiy🇩🇰 · Randall K. Smith🇺🇸

    The recent discovery of the unidentified emission line at 3.55 keV in galaxies and clusters has attracted great interest from the community. As the origin of the line remains uncertain, we study the surface brightness distribution of the line in the Perseus cluster since that information can be used to identify its origin. We examine the flux distribution of the 3.55 keV line in the deep Suzaku observations of the Perseus cluster in detail. The 3.55 keV line is observed in three concentric annuli in the central observations, although the observations of the outskirts of the cluster did not reveal such a signal. We establish that these detections and the upper limits from the non-detections are consistent with a dark matter decay origin. However, absence of positive detection in the outskirts is also consistent with some unknown astrophysical origin of the line in the dense gas of the Perseus core, as well as with a dark matter origin with a steeper dependence on mass than the dark matter decay. We also comment on several recently published analyses of the 3.55 keV line.

    ↳ astro-ph.COastro-ph.HEhep-phApJ(2016)·56 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.