Fri·Mar 11, 2016Friday·March 11, 2016

1. 01*

   Deuterium target data for precision neutrino-nucleus cross sections

   Aaron S. Meyer🇺🇸 · Minerba Betancourt🇺🇸 · Richard Gran🇺🇸 · Richard J. Hill🇺🇸

   Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, $F_A(q^2)$, which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of $F_A$ from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of $F_A$. A complete error budget for the nucleon isovector axial radius leads to $r_A^2=0.46(22){\mathrm{fm}}^2$, with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as $\sigma ({\nu }_{\mu }n\to {\mu }^{-}p){|}_{E_{\nu }=1\mathrm{GeV}}=10.1(0.9)\times 10^{-39}{\mathrm{cm}}^2$. The propagation of nucleon-level constraints and uncertainties to nuclear cross sections is illustrated using MINERvA data and the GENIE event generator. These techniques can be readily extended to other amplitudes and processes.

   hep-phhep-exnucl-exnucl-thPRD(2016)·242 citations
2. 02*

   Is there room for CP violation in the top-Higgs sector?

   V. Cirigliano🇺🇸 · W. Dekens🇺🇸 · J. de Vries🇳🇱 · E. Mereghetti🇺🇸

   We discuss direct and indirect probes of chirality-flipping couplings of the top quark to Higgs and gauge bosons, considering both CP-conserving and CP-violating observables, in the framework of the Standard Model effective field theory. In our analysis we include current and prospective constraints from collider physics, precision electroweak tests, flavor physics, and electric dipole moments (EDMs). We find that low-energy indirect probes are very competitive, even after accounting for long-distance uncertainties. In particular, EDMs put constraints on the electroweak CP-violating dipole moments of the top that are two to three orders of magnitude stronger than existing limits. The new indirect constraint on the top EDM is given by $|d_t|<5\cdot 10^{-20}$ e cm at $90\%$ C.L.

   hep-phPRD(2016)·123 citations
3. 03*

   Impact of Jet Veto Resummation on Slepton Searches

   Frank J. Tackmann🇩🇪 · Wouter J. Waalewijn🇳🇱 · Lisa Zeune🇳🇱

   Several searches for new physics at the LHC require a fixed number of signal jets, vetoing events with additional jets from QCD radiation. As the probed scale of new physics gets much larger than the jet-veto scale, such jet vetoes strongly impact the QCD perturbative series, causing nontrivial theoretical uncertainties. We consider slepton pair production with 0 signal jets, for which we perform the resummation of jet-veto logarithms and study its impact. Currently, the experimental exclusion limits take the jet-veto cut into account by extrapolating to the inclusive cross section using parton shower Monte Carlos. Our results indicate that the associated theoretical uncertainties can be large, and when taken into account have a sizeable impact already on present exclusion limits. This is improved by performing the resummation to higher order, which allows us to obtain accurate predictions even for high slepton masses. For the interpretation of the experimental results to benefit from improved theory predictions, it would be useful for the experimental analyses to also provide limits on the unfolded visible 0-jet cross section.

   hep-phhep-exJHEP(2016)·19 citations
4. 04*

   Taming systematic uncertainties at the LHC with the central limit theorem

   Sylvain Fichet🇧🇷

   We study the simplifications occurring in any likelihood function in the presence of a large number of small systematic uncertainties. We find that the marginalisation of these uncertainties can be done analytically by means of second-order error propagation, error combination, the Lyapunov central limit theorem, and under mild approximations which are typically satisfied for LHC likelihoods. The outcomes of this analysis are i) a very light treatment of systematic uncertainties ii) a convenient way of reporting the main effects of systematic uncertainties such as the detector effects occuring in LHC measurements.

   hep-phhep-exphysics.data-anNPB(2016)·13 citations
5. 05*

   Comment on "Analysis of General Power Counting Rules in Effective Field Theory"

   G. Buchalla🇩🇪 · O. Cata🇩🇪 · A. Celis🇩🇪 · C. Krause🇩🇪

   In a recent paper [1] a master formula has been presented for the power counting of a general effective field theory. We first show that this master formula follows immediately from the concept of chiral dimensions (loop counting), together with standard dimensional analysis. Subsequently, [1] has disputed the relevance of chiral counting for chiral Lagrangians, and in particular for the electroweak chiral Lagrangian including a light Higgs boson. As an alternative, a power counting based on `primary dimensions' has been proposed. The difficulties encountered with this scheme led the authors to suggest that even the leading order of the electroweak chiral Lagrangian could not be clearly defined. Here we demonstrate that the concept of primary dimensions is irrelevant for the organization of chiral Lagrangians. We re-emphasize that the correct counting is based on chiral dimensions, or the counting of loop orders, and show how the problems encountered in [1] are resolved.

   hep-ph29 citations
6. 06*

   Patterns of Strong Coupling for LHC Searches

   Da Liu🇨🇳 · Alex Pomarol🇪🇸 · Riccardo Rattazzi🇨🇭 · Francesco Riva🇨🇭

   Even though the Standard Model (SM) is weakly coupled at the Fermi scale, a new strong dynamics involving its degrees of freedom may conceivably lurk at slightly higher energies, in the multi TeV range. Approximate symmetries provide a structurally robust context where, within the low energy description, the dimensionless SM couplings are weak, while the new strong dynamics manifests itself exclusively through higher-derivative interactions. We present an exhaustive classification of such scenarios in the form of effective field theories, paying special attention to new classes of models where the strong dynamics involves, along with the Higgs boson, the SM gauge bosons and/or the fermions. The IR softness of the new dynamics suppresses its effects at LEP energies, but deviations are in principle detectable at the LHC, even at energies below the threshold for production of new states. Our construction provides the so far unique structurally robust context where to motivate several searches in Higgs physics, diboson production, or WW scattering, which were so far poorly justified. Perhaps surprisingly, the interplay between weak coupling, strong coupling and derivatives, which is controlled by symmetries, can override the naive expansion in operator dimension, providing instances where dimension-8 dominates dimension-6, well within the domain of validity of the low energy effective theory. This result reveals the limitations of an analysis that is both ambitiously general and restricted to dimension-6 operators.

   hep-phJHEP(2016)·117 citations
7. 07*

   The Standard Model in extra dimensions and its Kaluza-Klein effective Lagrangian

   I. García-Jiménez🇲🇽 · M. A. López-Osorio🇲🇽 · E. Martínez-Pascual🇲🇽 · G. I. Nápoles-Cañedo🇲🇽 · H. Novales-Sánchez🇲🇽 · J. J. Toscano🇲🇽

   We construct an effective theory for the SM with extra dimensions. We start from a theory governed by the extra-dimensional groups ISO$(1,3+n)$ and $G_{\mathrm{SM}}({\mathcal{M}}^{4+n})=S{U}_C(3,{\mathcal{M}}^{4+n})\times S{U}_L(2,{\mathcal{M}}^{4+n})\times U_Y(1,{\mathcal{M}}^{4+n})$, characterized by an unknown energy scale $\Lambda$ and valid at energies far below this scale. Assuming that the extra dimensions are much larger than the distance scale of this theory, we construct an effective theory with symmetry groups ISO(1,3), $G_{\mathrm{SM}}({\mathcal{M}}^4)$. The theories are connected by a canonical transformation that hides ISO$(1,3+n)$, $G_{\mathrm{SM}}({\mathcal{M}}^{4+n})$ into ISO(1,3), $G_{\mathrm{SM}}({\mathcal{M}}^4)$; KK fields receive mass. Using a set of orthogonal functions $\{f^{(\underline{0})},f^{(\underline{m})}\}$, generated by the Casimir invariant ${\bar{P}}^2$ associated with the translations subgroup $T(n)\subset$ISO$(n)$, we expand the degrees of freedom of ISO$(1,3+n)$, $G_{\mathrm{SM}}({\mathcal{M}}^{4+n})$ in general Fourier series, whose coefficients are the degrees of freedom of ISO(1,3), $G({\mathcal{M}}^4)$. These functions, which correspond to the projection on $\{|\bar{x}⟩\}$ of the discrete basis $\{|0⟩,|p^{(\underline{m})}⟩\}$ of ${\bar{P}}^2$, are central to define the effective theory. Components along the ground state $f^{(\underline{0})}=⟨\bar{x}|0⟩$ do not receive mass at the compactification scale, so they are the SM fields; components along excited states $f^{(\underline{m})}=⟨\bar{x}|p^{(\underline{m})}⟩$ get mass at this scale, so they are KK excitations. For any direction $|p^{(\underline{m})}\ne 0⟩$ there are a massive gauge field and a pseudo-Goldstone boson. We stress resemblances of this mass-generating mechanism with the Englert-Higgs mechanism and discuss physical implications. We include a full catalog of Lagrangian terms that can be used to calculate Feynman rules.

   hep-phhep-th6 citations
8. 08*

   Next-to-next-to-leading order QCD analysis of spin-dependent parton distribution functions and their uncertainties: Jacobi polynomials approach

   F. Taghavi Shahri🇮🇷 · Hamzeh Khanpour🇮🇷 · S. Atashbar Tehrani🇮🇷 · Z. Alizadeh Yazdi🇮🇷

   We present a first QCD analysis of next-to-next-leading-order (NNLO) contributions of the spin-dependent parton distribution functions (PPDFs) in the nucleon and their uncertainties using the Jacobi polynomial approach. Having the NNLO contributions of the quark-quark and gluon-quark splitting functions in perturbative QCD (Nucl. Phys. B 889 (2014) 351-400), one can obtain the evolution of longitudinally polarized parton densities of hadrons up to NNLO accuracy of QCD. A very large sets of recent and up-to-date experimental data of spin structure functions of the proton $g_1^p$, neutron $g_1^n$, and deuteron $g_1^d$ have been used in this analysis. The predictions for the NNLO calculations of the polarized parton distribution functions as well as the proton, neutron and deuteron polarized structure functions are compared with the corresponding results of the NLO approximation. We form a mutually consistent set of polarized PDFs due to the inclusion of the most available experimental data including the recently high-precision measurements from {\tt COMPASS16} experiments (Phys. Lett. B 753 (2016) 18-28). We have performed a careful estimation of the uncertainties using the most common and practical method, the Hessian method, for the polarized PDFs originating from the experimental errors. The proton, neutron and deuteron structure functions and also their first moments, ${\Gamma }^{\mathrm{p},\mathrm{n},\mathrm{d}}$, are in good agreement with the experimental data at small and large momentum fraction of $x$. We will discuss how our knowledge of spin-dependence structure functions can improve at small and large value of $x$ by the recent {\tt COMPASS16} measurements at CERN, the {\tt PHENIX} and {\tt STAR} measurements at RHIC, and at the future proposed colliders such as Electron-Ion collider (EIC).

   hep-phPRD(2016)·50 citations
9. 09*

   Large production rate of new $B_s^0{\pi }^{\pm }$ and $D_s^{\pm }{\pi }^{\pm }$ states in high energy multi-production process

   Yi Jin · Shi-Yuan Li

   The production rate of the X(5568) observed by D0 collabotation is quite large and can not be understood by various general hadronization mechanism. We propose an inclusive resonance production formulation to calculate the cross section and extract the value of the effective wave function at origin. Based on these results we suspect X($D_s{\pi }^{\pm }$) can be copiously produced and observable at high enenrgy scatterings (the relative production ratio to D_s is larger than 10 %). In the updated version the discussions on cluster model and FI are added. Both cases can not give large rate. Then we show that pion in X(5568) decay can only gain a very small momentum. In the pseudo-rapidity region [2,5], large part of the signal pions will be dismissed by the detector since the transverse mometum is too small and/or total momentum too small. If further requirement on pion tranverse mometum larger than 1GeV/c added, almost all signal pions are rejected. But for the charm partner, this problem does not exist since the charm partner can give a larger boost factor. A 3D distribution of signal pions are added

   hep-phPRD(2016)·31 citations
10. 10*

    Self-induced temporal instability from a neutrino antenna

    Francesco Capozzi (Padua Univ. & INFN Padua)🇮🇹 · Basudeb Dasgupta (TIFR, Mumbai)🇮🇳 · Alessandro Mirizzi (Bari Univ. & INFN Bari)🇮🇹

    It has been recently shown that the flavor composition of a self-interacting neutrino gas can spontaneously acquire a time-dependent pulsating component during its flavor evolution. In this work, we perform a more detailed study of this effect in a model where neutrinos are assumed to be emitted in a two-dimensional plane from an infinite line that acts as a neutrino antenna. We consider several examples with varying matter and neutrino densities and find that temporal instabilities with various frequencies are excited in a cascade. We compare the numerical calculations of the flavor evolution with the predictions of linearized stability analysis of the equations of motion. The results obtained with these two approaches are in good agreement in the linear regime, while a dramatic speed-up of the flavor conversions occurs in the non-linear regime due to the interactions among the different pulsating modes. We show that large flavor conversions can take place if some of the temporal modes are unstable for long enough, and that this can happen even if the matter and neutrino densities are changing, as long as they vary slowly.

    hep-phastro-ph.HEJCAP(2016)·29 citations
11. 11*

    Unparticle contribution to the hydrogen atom ground state energy

    Michael F. Wondrak🇩🇪 · Piero Nicolini🇩🇪 · Marcus Bleicher🇩🇪

    In the present work we study the effect of unparticle modified static potentials on the energy levels of the hydrogen atom. By using Rayleigh-Schrödinger perturbation theory, we obtain the energy shift of the ground state and we compare it with experimental data. Bounds on the unparticle energy scale ${\Lambda }_{\mathcal{U}}$ as a function of the scaling dimension $d_{\mathcal{U}}$ and the coupling constant $\lambda$ are derived. We show that there exists a parameter region where bounds on ${\Lambda }_{\mathcal{U}}$ are stringent, signalling that unparticles could be tested in atomic physics experiments.

    hep-phhep-thphysics.atom-phPLB(2016)·12 citations
12. 12*

    X(5568) as a $su\bar{d}\bar{b}$ tetraquark in a simple quark model

    Fl. Stancu🇧🇪

    The $S$-wave eigenstates of tetraquarks of type $su\bar{d}\bar{b}$ with J${}^P$ = 0${}^{+}$, 1${}^{+}$ and 2${}^{+}$ are studied within a simple quark model with chromomagnetic interaction and effective quark masses extracted from meson and baryon spectra. It is tempting to see if this spectrum can accommodate the new narrow structure X(5568), observed by the DØ~~Collaboration, but not confirmed by the LHCb Collaboration. If it exists, such a tetraquark is a system with four different flavors and its study can improve our understanding of multiquark systems. The presently calculated mass of X(5568) agrees quite well with the experimental value of he DØ~~Collaboration. Predictions are made for the spectrum of the charmed partner $su\bar{d}\bar{c}$. However we are aware of the difficulty of extracting effective quark masses, from mesons and baryons, to be used in multiquark systems.

    hep-phJ.Phys.G(2016)·40 citations
13. 13*

    Transient anomalous charge production in strong-field QCD

    N. Tanji🇩🇪 · N. Mueller🇩🇪 · J. Berges🇩🇪

    We investigate axial charge production in two-color QCD out of equilibrium. We compute the real-time evolution starting with spatially homogeneous strong gauge fields, while the fermions are in vacuum. The idealized class of initial conditions is motivated by glasma flux tubes in the context of heavy-ion collisions. We focus on axial charge production at early times, where important aspects of the anomalous dynamics can be derived analytically. This is compared to real-time lattice simulations. Quark production at early times leading to anomalous charge generation is investigated using Wilson fermions. Our results indicate that coherent gauge fields can transiently produce significant amounts of axial charge density, while part of the induced charges persist to be present even well beyond characteristic decoherence times. The comparisons to analytic results provide stringent tests of real-time representations of the axial anomaly on the lattice.

    hep-phhep-latnucl-thPRD(2016)·26 citations
14. 14*

    A Dark Sector for $g_{\mu }-2$, $R_K$ and a Diphoton Resonance

    Geneviève Bélanger🇫🇷 · Cédric Delaunay🇫🇷

    We revisit a set of dark sector models, motivated by anomalies observed in $B$ decays and the muon anomalous magnetic moment, in the light of a recently reported diphoton excess around 750GeV. Interpreting the excess as a scalar resonance associated with the symmetry breaking sector of a dark gauge group, we show that a diphoton cross section of few fb can be accomodated, together with anomalies in $R_K$ and $g_{\mu }-2$ within a minimal dark sector model. The resulting prominent collider signatures are in the form of wide resonant signals into top and muon pair final states below $\sim 1$TeV. The model further predicts a dark matter candidate, yet with a significantly underabundant relic density, unless produced by an appropriate non-thermal mechanism.

    hep-phPRD(2016)·23 citations
15. 15*

    Interstellar Gas and a Dark Disk

    Eric David Kramer🇺🇸 · Lisa Randall🇺🇸

    We introduce a potentially powerful method for constraining or discovering a thin dark matter disk in the Milky Way. The method relies on the relationship between the midplane densities and scale heights of interstellar gas being determined by the gravitational potential, which is sensitive to the presence of a dark disk. We show how to use the interstellar gas parameters to set a bound on a dark disk and discuss the constraints suggested by the current data. However, current measurements for these parameters are discordant, with the uncertainty in the constraint being dominated by the molecular hydrogen midplane density measurement, as well as by the atomic hydrogen velocity dispersion measurement. Magnetic fields and cosmic ray pressure, which are expected to play a role, are uncertain as well. The current models and data are inadequate to determine the disk's existence, but, taken at face value, may favor its existence depending on the gas parameters used.

    ↳ astro-ph.GAhep-phApJ(2016)·35 citations
16. 16*

    Electric dipole moment of ${}^{13}$C

    Nodoka Yamanaka🇫🇷 · Taiichi Yamada🇯🇵 · Emiko Hiyama🇯🇵 · Yasuro Funaki🇨🇳

    We calculate for the first time the electric dipole moment (EDM) of ${}^{13}$C generated by the isovector CP-odd pion exchange nuclear force in the $\alpha$-cluster model, which describes well the structures of low lying states of the ${}^{13}$C nucleus. The linear dependence of the EDM of ${}^{13}$C on the neutron EDM and the isovector CP-odd nuclear coupling is found to be $d_{{}^{13}\mathrm{C}}=-0.33d_n-0.0020{\bar{G}}_{\pi }^{(1)}$. The linear enhancement factor of the CP-odd nuclear coupling is smaller than that of the deuteron, due to the difference of the structure between the $1/2_1^{-}$ state and the opposite parity ($1/2^{+}$) states. We clarify the role of the structure played in the enhancement of the EDM. This result provides good guiding principles to search for other nuclei with large enhancement factor. We also mention the role of the EDM of ${}^{13}$C in determining the new physics beyond the standard model.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2017)·29 citations
17. 17*

    The Influence of Modification of Gravity on the Dynamics of Radiating Spherical Fluids

    Z. Yousaf🇵🇰 · Kazuharu Bamba🇯🇵 · M. Zaeem ul Haq Bhatti🇵🇰

    We explore the evolutionary behaviors of compact objects in a modified gravitational theory with the help of structure scalars. Particularly, we consider the spherical geometry coupled with heat and radiation emitting shearing viscous matter configurations. We construct structure scalars by splitting the Riemann tensor orthogonally in $f(R,T)$ gravity with and without constant $R$ and $T$ constraints, where $R$ is the Ricci scalar and $T$ is the trace of the energy-momentum tensor. We investigate the influence of modification of gravity on the physical meaning of scalar functions for radiating spherical matter configurations. It is explicitly demonstrated that even in modified gravity, the evolutionary phases of relativistic stellar systems can be analyzed through the set of modified scalar functions.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2016)·161 citations
18. 18*

    The Corolla Polynomial for spontaneously broken Gauge Theories

    David Prinz🇩🇪

    In [1, 2, 3] the Corolla Polynomial $\mathcal{C}(\Gamma )\in \mathbb{C}[a_{h_1},\dots ,a_{h_{|{\Gamma }^{[1/2]}|}}]$ was introduced as a graph polynomial in half-edge variables ${\left\{a_h\right\}}_{h\in {\Gamma }^{[1/2]}}$ over a 3-regular scalar quantum field theory (QFT) Feynman graph $\Gamma$. It allows for a covariant quantization of pure Yang-Mills theory without the need for introducing ghost fields, clarifies the relation between quantum gauge theory and scalar QFT with cubic interaction and translates back the problem of renormalizing quantum gauge theory to the problem of renormalizing scalar QFT with cubic interaction (which is super renormalizable in 4 dimensions of spacetime). Furthermore, it is, as we believe, useful for computer calculations. In [4] on which this paper is based the formulation of [1, 2, 3] gets slightly altered in a fashion specialized in the case of the Feynman gauge. It is then formulated as a graph polynomial $\mathcal{C}(\Gamma )\in \mathbb{C}[a_{h_{1\pm }},\dots ,a_{h_{|{\Gamma }^{[1/2]}|}{}_{\pm }},b_{h_1},\dots ,b_{h_{|{\Gamma }^{[1/2]}|}}]$ in three different types of half-edge variables ${\left\{a_{h_{+}},a_{h_{-}},b_h\right\}}_{h\in {\Gamma }^{[1/2]}}$. This formulation is also suitable for the generalization to the case of spontaneously broken gauge theories (in particular all bosons from the Standard Model), as was first worked out in [4] and gets reviewed here.

    ↳ math-phhep-phhep-thmath.MPMath.Phys.Anal.Geom.(2016)·17 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.