Fri·May 13, 2016Friday·May 13, 2016

1. 01*

   Predictions for bottomonia suppression in 5.023 TeV Pb-Pb collisions

   Brandon Krouppa🇺🇸 · Michael Strickland🇺🇸

   We compute the suppression of the bottomonia states Upsilon(1S), Upsilon(2S), Upsilon(3S), chi_b(1P), chi_b(2P), and chi_b(3P) states in Large Hadron Collider (LHC) sqrt(s_NN)) = 5.023 TeV Pb-Pb collisions. For the background evolution we use 3+1d anisotropic hydrodynamics with conditions extrapolated from sqrt(s_NN) = 2.76 TeV and we self-consistently compute bottomonia decay rates including non-equilibrium corrections to the interaction potential. For our final results, we make predictions for R_AA as function of centrality, rapidity, and p_T for the Upsilon(1S) and Upsilon(2S) states, including feed down effects. In order to assess the dependence on some of the model assumptions, we vary the shear viscosity-to-entropy density ratio, 4 pi eta/s = (1, 2, 3), and the initial momentum-space anisotropy parameter, xi_0 = (0, 10, 50), while holding the total light hadron multiplicity fixed.

   hep-phnucl-exnucl-thUniverse(2016)·88 citations
2. 02*

   Bottom-Up Discrete Symmetries for Cabibbo Mixing

   Ivo de Medeiros Varzielas🇬🇧 · Rasmus W. Rasmussen🇩🇪 · Jim Talbert🇬🇧

   We perform a bottom-up search for discrete non-Abelian symmetries capable of quantizing the Cabibbo angle that parameterizes CKM mixing. Given a particular Abelian symmetry structure in the up and down sectors, we construct representations of the associated residual generators which explicitly depend on the degrees of freedom present in our effective mixing matrix. We then discretize those degrees of freedom and utilize the Groups, Algorithms, Programming (GAP) package to close the associated finite groups. This short study is performed in the context of recent results indicating that, without resorting to special model-dependent corrections, no small-order finite group can simultaneously predict all four parameters of the three-generation CKM matrix and that only groups of $\mathcal{O}(10^2)$ can predict the analogous parameters of the leptonic PMNS matrix, regardless of whether neutrinos are Dirac or Majorana particles. Therefore a natural model of flavour might instead incorporate small(er) finite groups whose predictions for fermionic mixing are corrected via other mechanisms.

   hep-phInt.J.Mod.Phys.A(2017)·25 citations
3. 03*

   750 GeV Diphotons: Implications for Supersymmetric Unification II

   Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸 · Yasunori Nomura🇺🇸

   Perturbative supersymmetric gauge coupling unification is possible in six theories where complete SU(5) TeV-scale multiplets of vector matter account for the size of the reported $750\mathrm{GeV}$ diphoton resonance, interpreted as a singlet multiplet $S=(s+ia)/\sqrt{2}$. One of these has a full generation of vector matter and a unified gauge coupling ${\alpha }_G\sim 1$. The diphoton signal rate is enhanced by loops of vector squarks and sleptons, especially when the trilinear $A$ couplings are large. If the $S{H}_u{H}_d$ coupling is absent, both $s$ and $a$ can contribute to the resonance, which may then have a large apparent width if the mass splitting from $s$ and $a$ arises from loops of vector matter. The width depends sensitively on $A$ parameters and phases of the vector squark and slepton masses. Vector quarks and/or squarks are expected to be in reach of the LHC. If the $S{H}_u{H}_d$ coupling is present, $a$ leads to a narrow diphoton resonance, while a second resonance with decays $s\to hh,W^{+}{W}^{-},ZZ$ is likely to be discovered at future LHC runs. In some of the theories a non-standard origin or running of the soft parameters is required, for example involving conformal hidden sector interactions.

   hep-phhep-exJHEP(2016)·9 citations
4. 04*

   Geometry of the Scalar Sector

   Rodrigo Alonso🇺🇸 · Elizabeth E. Jenkins🇺🇸 · Aneesh V. Manohar🇺🇸

   The $S$-matrix of a quantum field theory is unchanged by field redefinitions, and so only depends on geometric quantities such as the curvature of field space. Whether the Higgs multiplet transforms linearly or non-linearly under electroweak symmetry is a subtle question since one can make a coordinate change to convert a field that transforms linearly into one that transforms non-linearly. Renormalizability of the Standard Model (SM) does not depend on the choice of scalar fields or whether the scalar fields transform linearly or non-linearly under the gauge group, but only on the geometric requirement that the scalar field manifold $\mathcal{M}$ is flat. We explicitly compute the one-loop correction to scalar scattering in the SM written in non-linear Callan-Coleman-Wess-Zumino (CCWZ) form, where it has an infinite series of higher dimensional operators, and show that the $S$-matrix is finite. Standard Model Effective Field Theory (SMEFT) and Higgs Effective Field Theory (HEFT) have curved $\mathcal{M}$, since they parametrize deviations from the flat SM case. We show that the HEFT Lagrangian can be written in SMEFT form if and only if $\mathcal{M}$ has a $SU(2{)}_L\times U(1{)}_Y$ invariant fixed point. Experimental observables in HEFT depend on local geometric invariants of $\mathcal{M}$ such as sectional curvatures, which are of order $1/{\Lambda }^2$, where $\Lambda$ is the EFT scale. We give explicit expressions for these quantities in terms of the structure constants for a general $\mathcal{G}\to \mathcal{H}$ symmetry breaking pattern. (Full abstract in pdf)

   hep-phJHEP(2016)·188 citations
5. 05*

   On the ultimate uncertainty of the top quark pole mass

   M. Beneke🇩🇪 · P. Marquard🇩🇪 · P. Nason🇮🇹 · M. Steinhauser🇩🇪

   We combine the known asymptotic behaviour of the QCD perturbation series expansion, which relates the pole mass of a heavy quark to the MSbar mass, with the exact series coefficients up to the four-loop order to determine the ultimate uncertainty of the top-quark pole mass due to the renormalon divergence. We perform extensive tests of our procedure by varying the number of colours and flavours, as well as the scale of the strong coupling and the MSbar mass. Including an estimate of the internal bottom and charm quark mass effect, we conclude that this uncertainty is around 110 MeV. We further estimate the additional contribution to the mass relation from the five-loop correction and beyond to be around 300 MeV.

   hep-phPLB(2017)·126 citations
6. 06*

   Imperfect Mirrors of the Standard Model

   Jeffrey M. Berryman🇺🇸 · André de Gouvêa🇺🇸 · Daniel Hernández🇺🇸 · Kevin J. Kelly🇺🇸

   Inspired by the Standard Model of particle physics, we discuss a mechanism for constructing chiral, anomaly-free gauge theories. The gauge symmetries and particle content of such theories are identified using subgroups and complex representations of simple anomaly-free Lie groups, such as $SO(10)$ or $E_6$. We explore, using mostly $SO(10)$ and the $16$ representation, several of these "imperfect copies" of the Standard Model, including $U(1{)}^N$ theories, $SU(5)\otimes U(1)$ theories, $SU(4)\otimes U(1{)}^2$ theories with 4-plets and 6-plets, and chiral $SU(3)\otimes SU(2)\otimes U(1)$. A few general properties of such theories are discussed, as well as how they might shed light on nonzero neutrino masses, the dark matter puzzle, and other phenomenologically relevant questions.

   hep-phPRD(2016)·14 citations
7. 07*

   Light Sterile Neutrinos, Lepton Number Violating Interactions and the LSND Anomaly

   K. S. Babu🇺🇸 · Douglas W. McKay🇺🇸 · Irina Mocioiu🇺🇸 · Sandip Pakvasa🇺🇸

   We develop the consequences of introducing a purely leptonic, lepton number violating non-standard interaction (NSI) and standard model neutrino mixing with a fourth, sterile neutrino in the analysis of short-baseline, neutrino experiments. We focus on the muon decay at rest (DAR) result from the Liquid Scintillation Neutrino Experiment (LSND) and the Karlsruhe and Rutherford Medium Energy Neutrino Experiment (KARMEN). We make a comprehensive analysis of lepton number violating, NSI effective operators and find nine that affect muon decay relevant to LSND results. Two of these preserve the standard model (SM) value 3/4 for the Michel rho and delta parameters and, overall, show favorable agreement with precision data and the electron anti-neutrino signal from LSND data. We display theoretical models that lead to these two effective operators. In the model we choose to apply to DAR data, both electron anti-neutrino appearance from muon anti-neutrino oscillation and electron anti-neutrino survival after production from NSI decay of the positive muon contribute to the expected signal. This is a unique feature of our scheme. We find a range of parameters where both experiments can be accommodated consistently with recent global, sterile neutrino fits to short baseline data. We comment on implications of the models for new physics searches at colliders and comment on further implications of the lepton number violating interactions plus sterile neutrino-standard model neutrino mixing.

   hep-phhep-exPRD(2016)·20 citations
8. 08*

   Probing Radiative Neutrino Mass Models Using Trilepton Channel at the LHC

   Dounia Cherigui🇩🇿 · Chahrazed Guella (Oran, Sci. Tech. U.)🇩🇿 · Amine Ahriche (Jijel U. and ICTP, Trieste and NCTS, Taipei)🇩🇿 · Salah Nasri (United Arab Emirates U.)🇦🇪

   In this work, we probe a class of neutrino mass models through the lepton flavor violating interactions of a singlet charged scalar, $S^{\pm }$ at the LHC proton-proton collisions with 8 TeV and 14 TeV energies. This scalar couples to the leptons and induces many processes such as $pp\to {\ell }^{\pm }{\ell }^{\pm }{\ell }^{\mp }+\text{slashed}{E}_T$. In our analysis we discuss the opposite sign same flavor leptons signal, as well as the background free channel with the tau contribution which can enhance the signal/background ratio for center of mass energies $\sqrt{s}$= 8 TeV and $\sqrt{s}$ = 14 TeV.

   hep-phhep-exPLB(2016)·17 citations
9. 09*

   Unraveling the CP phase of top-Higgs coupling in associated production at the LHC

   Saurabh D. Rindani🇮🇳 · Pankaj Sharma🇦🇺 · Ambresh Shivaji🇮🇹

   We study the sensitivity of top polarization observables to the CP phase ${\zeta }_t$ in the top Yukawa coupling in the process $pp\to thj$ at the 14 TeV high-luminosity run of the Large Hadron Collider (HL-LHC). We calculate the top polarization in this process as well as an azimuthal asymmetry of the charged lepton arising from the decay of the top in the lab frame. We find that the dependence of this lab-frame azimuthal asymmetry on the phase ${\zeta }_t$ closely resembles the dependence of the top polarization on ${\zeta }_t$. As compared to the cross section, which is sensitive to ${\zeta }_t$ for larger values, the lepton azimuthal asymmetry can provide a sensitive measurement of ${\zeta }_t$ for smaller values.

   hep-phPLB(2016)·24 citations
10. 10*

    A broad 750 GeV diphoton resonance? Not alone

    P. Roig🇲🇽 · J.J. Sanz-Cillero🇪🇸

    The hint for a possible resonance in the diphoton channel with mass of 750~GeV disappeared in the data presented at ICHEP'16 by ATLAS and CMS. However, the diphoton final state remains as one of the golden channels for new physics discoveries at the TeV scale in the LHC experiments. This motivates us to analyze model-independently the implications of an O(TeV) bump in the $\gamma \gamma$ final state. By means of forward sum-rules for $\gamma \gamma$ scattering, we show that a spin-0 resonance with mass of the order of the TeV and a sizable $\gamma \gamma$ partial width -of the order of a few GeV- must be accompanied by higher spin resonances with $J_R\ge 2$ with similar properties, as expected in strongly coupled extensions of the Standard Model or, alternatively, in higher dimensional deconstructed duals. Furthermore, independently of whether the putative O(TeV) candidate is a scalar or a tensor, the large contribution to the forward sum-rules in the referred scenario implies the presence of states in the spectrum with $J_R\ge 2$, these high spin particles being a manifestation of new extra-dimensions or composite states of a new strong sector.

    hep-phPRD(2016)·10 citations
11. 11*

    A bottom-up approach to the strong CP problem

    J. L. Díaz-Cruz🇲🇽 · W. G. Hollik🇩🇪 · U. J. Saldaña-Salazar🇲🇽

    The strong CP problem is one of many puzzles in the theoretical description of elementary particle physics that still lacks an explanation. While top-down solutions to that problem usually comprise new symmetries or fields or both, we want to present a rather bottom-up perspective. The main problem seems to be how to achieve small CP violation in the strong interactions despite large CP violation in weak interactions. Observation of CP violation is exclusively through the Higgs--Yukawa interactions. In this paper, we show that with minimal assumptions on the structure of mass (Yukawa) matrices they do not contribute to the strong CP problem and thus we can provide a pathway to a solution of the strong CP problem within the structures of the Standard Model and no extension at the electroweak scale is needed. However, to address the flavor puzzle, models based on minimal SU(3) flavor groups leading to the proposed flavor matrices are favored. Though we refrain from an explicit a UV completion of the Standard Model, we provide a simple requirement those models should have to intrinsically not show a strong CP problem.

    hep-phInt.J.Mod.Phys.A(2018)·12 citations
12. 12*

    Balitsky-Kovchegov equation at next-to-leading order accuracy with a resummation of large logarithms

    T. Lappi🇫🇮 · H. Mäntysaari🇺🇸

    We include resummation of large transverse logarithms into the next-to-leading order Balitsky-Kovchegov equation. The resummed NLO evolution equation is shown to be stable, the evolution speed being significantly reduced by higher order corrections. The contributions from ${\alpha }_s^2$ terms that are not enhanced by large logarithms are found to be numerically important close to phenomenologically relevant initial conditions.

    hep-phnucl-thPoS(2016)·0 citations
13. 13*

    Leading and next to leading large $n_f$ terms in the cusp anomalous dimension and the quark-antiquark potential

    Andrey Grozin🇷🇺

    I discuss 3 related quantities: the cusp anomalous dimension, the HQET heavy-quark field anomalous dimension, and the quark-antiquark potential. Leading large $n_f$ terms can be calculated to all orders in ${\alpha }_s$. Next to leading terms with the abelian color structure $C_F^2$ also can be found to all orders (but not non-abelian $C_F{C}_A$ terms). This talk is based on Appendices C and D in [arXiv:1510.07803].

    hep-phhep-thPoS(2016)·22 citations
14. 14*

    Probing the noncommutative effects of phase space in the time-dependent Aharonov-Bohm effect

    Kai Ma🇨🇳 · Jian-Hua Wang🇨🇳 · Huan-Xiong Yang🇨🇳

    We study the noncommutative corrections on the time-dependent Aharonov-Bohm effect when both the coordinate-coordinate and momentum-momentum noncommutativities are considered. This study is motivated by the recent observation that there is no net phase shift in the time-dependent AB effect on the ordinary space, and therefore tiny derivation from zero can indicate new physics. The vanishing of the time-dependent AB phase shift on the ordinary space is preserved by the gauge and Lorentz symmetries. However, on the noncomutative phase space, while the ordinary gauge symmetry can be kept by the Seiberg-Witten map, but the Lorentz symmetry is broken. Therefore nontrivial noncommutative corrections are expected. We find there are three kinds of noncommutative corrections in general: 1) $\xi$-dependent correction which comes from the noncommutativity among momentum operators; 2) momentum-dependent correction which is rooted in the nonlocal interactions in the noncommutative extended model; 3) momentum-independent correction which emerges become of the gauge invariant condition on the nonlocal interactions in the noncommutative model. We proposed two dimensionless quantities, which are based on the distributions of the measured phase shift with respect to the external magnetic field and to the cross section enclosed by the particle trajectory, to extract the noncommutative parameters. We find that stronger (weaker) magnetic field strength can give better bounds on the coordinate-coordinate (momentum-momentum) noncommutative parameter, and large parameter space region can be explored by the time-dependent AB effect.

    hep-phquant-phAnnals Phys.(2017)·14 citations
15. 15*

    Production and Decay of 750 Gev state of 6 top and 6 anti top quarks

    Colin D. Froggatt🇬🇧 · Holger B. Nielsen🇩🇰

    Crude estimates are made of the branching ratios and pair production cross-section for our previously proposed bound state S of six top and six antitop quarks identified with the diphoton excess recently observed in ATLAS and CMS. We estimate the pair production cross section to be approximately 12 times that for fourth family quarks. Hence we predict $\sigma (pp\to SS+anything)\approx 2$ pb at 13 TeV and an increase by a factor 10 over the cross section at 8 TeV. Crude estimates of the main branching ratios relative to the diphoton decay give $\Gamma (S\to \gamma +\gamma )\propto 1$, $\Gamma (S\to t+\bar{t})\propto 378$, $\Gamma (S\to gluon+gluon)\propto 117$, $\Gamma (S\to Higgs+Higgs)\propto 15$, $\Gamma (S\to W+W)\propto 30$ and $\Gamma (S\to Z+Z)=15$. These estimates are consistent with the LHC bounds at 8 TeV within a factor 1.25. We expect the $S\to \gamma \gamma$ events to be produced together with another S resonance decaying typically into top-antitop or gluon-gluon jets.

    hep-ph7 citations
16. 16*

    Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    Carsten van de Bruck🇬🇧 · Clare Burrage🇬🇧 · Jack Morrice🇬🇧

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2016)·17 citations
17. 17*

    The chiral S=-1 meson-baryon interaction with new constrains on the NLO contributions

    A. Ramos🇪🇸 · A. Feijoo🇪🇸 · V.K. Magas🇪🇸

    We present a study of the $S=-1$ meson-baryon interaction, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the model have been fitted to a large set of experimental scattering data in different two-body channels, to threshold branching ratios, and to the precise SIDDHARTA value of the energy shift and width of kaonic hidrogen. In contrast to other groups, we have taken into consideration the $K^{-}p\to K^{+}{\Xi }^{-},K^0{\Xi }^0$ reaction data, since we found in a previous work to be especially sensitive to the NLO parameters of the chiral Lagrangian. In the present work we also include the Born terms, which usually have very little effect, and find them to be non-negligible in the $K^{-}p\to K\Xi$ channels, correspondingly causing significant modifications to the NLO parameters. We furthermore show that the importance of the Born terms becomes more visible in the isospin projected amplitudes of the $K^{-}p\to K\Xi$ reactions. The measurement of processes that filter single isospin components, like the $K_L^{0}p\to K^{+}{\Xi }^0$ reaction that could be measured at the proposed secondary $K_L^0$ beam at Jlab, would put valuable constraints on the chiral models describing the meson-baryon interaction in the $S=-1$ sector.

    ↳ nucl-thhep-phNPA(2016)·31 citations
18. 18*

    Gravitational waves from first order phase transitions as a probe of an early matter domination era and its inverse problem

    Gabriela Barenboim🇪🇸 · Wan-Il Park🇪🇸

    We investigate the gravitational wave background from a first order phase transition in a matter-dominated universe, and show that it has a unique feature from which important information about the properties of the phase transition and thermal history of the universe can be easily extracted. Also, we discuss the inverse problem of such a gravitational wave background in view of the degeneracy among macroscopic parameters governing the signal.

    ↳ astro-ph.COgr-qchep-phPLB(2016)·60 citations
19. 19*

    Neutrino physics and precision cosmology

    Steen Hannestad🇩🇰

    I review the current status of structure formation bounds on neutrino properties such as mass and energy density. I also discuss future cosmological bounds as well as a variety of different scenarios for reconciling cosmology with the presence of light sterile neutrinos.

    ↳ astro-ph.COhep-ph6 citations
20. 20*

    Summary of the 2015 LHCb workshop on multi-body decays of D and B mesons

    Jorge H. Alvarenga Nogueira · Sandra Amato · Alexander Austregesilo · Clarissa Baesso · Ignacio Bediaga Hickman · Eli Ben Haim · Eef van Beveren · Bhubanjyoti Bhattacharya · Ikaros Bigi · Diogo Boito · Jolanta Brodzicka · Marcelo Campos and 51 other authors

    This document contains a summary of the LHCb workshop on multi-body decays of D and B mesons, held at CBPF, Rio de Janeiro, in July 2015. The workshop was focused on issues related to amplitude analysis of three- and four-body hadronic decays. In addition to selected LHCb results, contributions from guest theorists are included.

    ↳ hep-exhep-ph30 citations
21. 21*

    Classical and Quantum Nonlocal Supergravity

    Stefano Giaccari🇭🇷 · Leonardo Modesto🇨🇳

    We derive the N=1 supersymmetric extension for a class of weakly nonlocal four dimensional gravitational theories.The construction is explicitly done in the superspace and the tree-level perturbative unitarity is explicitly proved both in the superfield formalism and in field components. For the minimal nonlocal supergravity the spectrum is the same as in the local theory and in particular it is ghost-free. The supersymmetric extension of the super-renormalizable Starobinsky theory and of two alternative massive nonlocal supergravities are found as straightforward applications of the formalism. Power-counting arguments ensure super-renormalizability with milder requirement for the asymptotic behavior of form factors than in ordinary nonlocal gravity. The most noteworthy result, common to ordinary supergravity, is the absence of quantum corrections to the cosmological constant in any regularization procedure. We cannot exclude the usual one-loop quadratic divergences. However, local vertices in the superfields, not undergoing renormalization, can be introduced to cancel out such divergences. Therefore, quantum finiteness is certainly achieved in dimensional regularization and most likely also in the cut-off regularization scheme. We also discuss the n-point scattering amplitudes making use of a general field redefinition theorem implemented in the superspace. Finally, we show that all the exact solutions of the local supergravity in vacuum are solutions of the nonlocal one too. In particular, we have the usual Schwarzschild singularity. We infer that the weak nonlocality, even in the presence of minimal supersymmetry, is not sufficient to solve the spacetime singularities issue, although the theory is finite at quantum level.

    ↳ hep-thgr-qchep-phPRD(2017)·29 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.