Wed·Oct 14, 2015Wednesday·October 14, 2015

1. 01*

   Pion Electromagnetic Form Factor in Virtuality Distribution Formalism

   A.V. Radyushkin🇺🇸

   We discuss two applications of the {\it Virtuality Distribution Amplitudes} (VDA) formalism developed in our recent papers. We start with an overview of the main properties of the pion distribution amplitude emphasizing the quantitative measures of its width, and possibility to access them through the pion transition form factor studies. We formulate the basic concepts of the VDA approach and introduce the pion transverse momentum distribution amplitude (TMDA) which plays, in a covariant Lagrangian formulation, a role similar to that of the pion wave function in the 3-dimensional Hamiltonian light-front approach. We propose simple factorized models for soft TMDAs, and use them to describe existing data on the pion transition form factor, thus fixing the scale determining the size of the transverse-momentum effects. Finally, we apply the VDA approach to the one-gluon exchange contribution for the pion electromagnetic form factor. We observe a very late $Q^2\gtrsim 20$ GeV${}^2$ onset of transition to the asymptotic pQCD predictions and show that in the $Q^2\lesssim 10$ GeV${}^2$ region there is essentially no sensitivity to the shape of the pion distribution amplitude. Furthermore, the magnitude of the one-gluon exchange contribution in this region is estimated to be an order of magnitude below the Jefferson Lab data, thus leaving the Feynman mechanism as the only one relevant to the pion electromagnetic form factor behavior for accessible $Q^2$.

   hep-phPoS(2015)·0 citations
2. 02*

   Strong CP and SUZ${}_2$

   Abdelhamid Albaid🇸🇦 · Michael Dine🇺🇸 · Patrick Draper🇺🇸

   Solutions to the strong CP problem typically introduce new scales associated with the spontaneous breaking of symmetries. Absent any anthropic argument for small $\bar{\theta }$, these scales require stabilization against ultraviolet corrections. Supersymmetry offers a tempting stabilization mechanism, since it can solve the "big" electroweak hierarchy problem at the same time. One family of solutions to strong CP, including generalized parity models, heavy axion models, and heavy ${\eta }^{\prime }$ models, introduces ${\mathbb{Z}}_2$ copies of (part of) the Standard Model and an associated scale of ${\mathbb{Z}}_2$-breaking. We review why, without additional structure such as supersymmetry, the ${\mathbb{Z}}_2$-breaking scale is unacceptably tuned. We then study "SUZ${}_2$" models, supersymmetric theories with ${\mathbb{Z}}_2$ copies of the MSSM. We find that the addition of SUSY typically destroys the ${\mathbb{Z}}_2$ protection of $\bar{\theta }=0$, even at tree level, once SUSY and ${\mathbb{Z}}_2$ are broken. In theories like supersymmetric completions of the twin Higgs, where ${\mathbb{Z}}_2$ addresses the little hierarchy problem but not strong CP, two axions can be used to relax $\bar{\theta }$.

   hep-phhep-thJHEP(2015)·42 citations
3. 03*

   Vacuum stability from vector dark matter

   Mateusz Duch🇵🇱 · Bohdan Grzadkowski🇵🇱 · Moritz McGarrie🇵🇱

   We study a model of vector dark matter with the complex scalar Higgs portal. Renormalisation group equations at the 2-loop level are used to analyse perturbativity and stability of the vacuum. We impose experimental and theoretical constraints on the model and find regions in the parameter space consistent with the dark matter relic abundance inferred from the Planck data and bounds on DM-nucleon scattering cross-section from XENON and LUX experiments.

   hep-phActa Phys.Polon.B(2015)·4 citations
4. 04*

   Branching ratio measurements and isospin violation in B-meson decays

   Martin Jung🇩🇪

   The approximate symmetry of the strong interactions under isospin transformations is among the most precise tools available to control hadronic matrix elements. It is crucial in extracting fundamental parameters, but also provides avenues for the search of phenomena beyond the Standard Model. The precision of the resulting predictions requires special care when determining the quantities they are to be tested with. Specifically, in the extraction of branching ratios often isospin symmetry is assumed at one point or another implicitly, implying a significant bias for precision analyses. We extract a bias-free value for the production asymmetry between charged and neutral $B$ meson pairs at $B$ factories and discuss its consequences for the determination of branching fractions generally, and isospin-violating observables like the rate asymmetries in B -> J/psi K or B -> K* gamma decays specifically.

   hep-phhep-exPLB(2016)·36 citations
5. 05*

   Dark Matter phenomenology of intersecting D6-branes with a Stueckelberg portal

   Victor Martin-Lozano🇪🇸

   We discuss the possibility that a Stueckelberg portal connects both Standard Model and Dark Matter sectors. The particle responsible of this portal is the lightest Z' boson that induces isospin-violating interactions. This property leads to a rich phenomenology for the direct detection and collider experiments that can constraint the parameter space of this kind of models and can be tested in the future.

   hep-phastro-ph.COhep-thPoS(2015)·0 citations
6. 06*

   Confronting the Inert Doublet Model with results from Run 1 of the LHC

   Dipan Sengupta🇫🇷

   The Inert Doublet Model (IDM) is a simple extension of the Standard Model (SM) that aims to address the naturalness problem, electroweak baryogenesis and accommodate a viable dark matter (DM) candidate, along with a rich phenomenlogy in terms of collider signatures. In this note, we address the constraints on the IDM by recasting dilepton + missing energy searches performed for Supersymmetry at LHC run-1 using Madanalysis5.

   hep-phPoS(2015)·0 citations
7. 07*

   The Coannihilation Codex

   Michael J. Baker🇩🇪 · Joachim Brod🇩🇪 · Sonia El Hedri🇩🇪 · Anna Kaminska🇩🇪 · Joachim Kopp🇩🇪 · Jia Liu🇩🇪 · Andrea Thamm🇩🇪 · Maikel de Vries🇩🇪 · Xiao-Ping Wang🇩🇪 · Felix Yu🇩🇪 · José Zurita🇩🇪

   We present a general classification of simplified models that lead to dark matter (DM) coannihilation processes of the form DM + X $\to$ SM${}_1$ + SM${}_2$, where X is a coannihilation partner for the DM particle and SM${}_1$, SM${}_2$ are Standard Model fields. Our classification also encompasses regular DM pair annihilation scenarios if DM and X are identical. Each coannhilation scenario motivates the introduction of a mediating particle M that can either belong to the Standard Model or be a new field, whereby the resulting interactions between the dark sector and the Standard Model are realized as tree-level and dimension-four couplings. We construct a basis of coannihilation models, classified by the $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ quantum numbers of DM, X and M. Our main assumptions are that dark matter is an electrically neutral color singlet and that all new particles are either scalars, Dirac or Majorana fermions, or vectors. We illustrate how new scenarios arising from electroweak symmetry breaking effects can be connected to our electroweak symmetric simplified models. We offer a comprehensive discussion of the phenomenological features of our models, encompassing the physics of thermal freeze-out, direct and indirect detection constraints, and in particular searches at the Large Hadron Collider (LHC). Many novel signatures that are not covered in current LHC searches are emphasized, and new and improved LHC analyses tackling these signatures are proposed. We discuss how the coannihilation simplified models can be used to connect results from all classes of experiments in a straightforward and transparent way. This point is illustrated with a detailed discussion of the phenomenology of a particular simplified model featuring leptoquark-mediated dark matter coannihilation.

   hep-phJHEP(2015)·122 citations
8. 08*

   Diboson anomaly: heavy Higgs resonance and QCD vector-like exotics

   D. Aristizabal Sierra🇧🇪 · J. Herrero-Garcia🇸🇪 · D. Restrepo🇨🇴 · A. Vicente🇪🇸

   The ATLAS collaboration (and also CMS) has recently reported an excess over Standard Model expectations for gauge boson pair production in the invariant mass region $1.8-2.2$ TeV. In the light of these results, we argue that such signal might be the first manifestation of the production and further decay of a heavy CP-even Higgs resulting from a type-I Two Higgs Doublet Model. We demonstrate that in the presence of colored vector-like fermions, its gluon fusion production cross-section is strongly enhanced, with the enhancement depending on the color representation of the new fermion states. Our findings show that barring the color triplet case, any QCD "exotic" representation can fit the ATLAS result in fairly large portions of the parameter space. We have found that if the diboson excess is confirmed and this mechanism is indeed responsible for it, then the LHC Run-2 should find: (i) a CP-odd scalar with mass below $\sim 2.3$ TeV, (ii) new colored states with masses below $\sim 2$ TeV, (iii) no statistically significant diboson events in the $W^{\pm }Z$ channel, (iv) events in the triboson channels $W^{\pm }{W}^{\mp }Z$ and $ZZZ$ with invariant mass amounting to the mass of the CP-odd scalar.

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

   Pushing Higgs Effective Theory to its Limits

   Johann Brehmer🇩🇪 · Ayres Freitas🇺🇸 · David Lopez-Val🇧🇪 · Tilman Plehn🇩🇪

   At the LHC, an effective theory of the Higgs sector allows us to analyze kinematic distributions in addition to inclusive rates, although there is no clear hierarchy of scales. We systematically analyze how well dimension-6 operators describe LHC observables in comparison to the full theory, and in a range where the LHC will be sensitive. The key question is how the breakdown of the dimension-6 description affects Higgs measurements during the upcoming LHC run for weakly interacting models. We cover modified Higgs sectors with a singlet and doublet extension, new top partners, and a vector triplet. First, weakly interacting models only generate small relevant subsets of dimension-6 operators. Second, the dimension-6 description tends to be justified at the LHC. Scanning over model parameters, significant discrepancies can nevertheless arise; their main source is the matching procedure in the absence of a well-defined hierarchy of scales. This purely theoretical problem should not affect future LHC analyses.

   hep-phPRD(2016)·111 citations
10. 10*

    Interference effect on heavy Higgs resonance signal in \gamma\gamma and ZZ channels

    Sunghoon Jung🇰🇷 · Jeonghyeon Song🇰🇷 · Yeo Woong Yoon🇰🇷

    The resonance-continuum interference is usually neglected when the width of a resonance is small compared to the resonance mass. We re-examine this standard by studying the interference effects in high-resolution decay channels, $\gamma \gamma$ and $ZZ$, of the heavy Higgs boson $H^0$ in nearly aligned two-Higgs-doublet models. For the $H^0$ with a sub-percent width-to-mass ratio, we find that, in the parameter space where the LHC 14 TeV $ZZ$ resonance search can be sensitive, the interference effects can modify the $ZZ$ signal rate by $\mathcal{O}(10)\%$ and the exclusion reach by $\mathcal{O}(10)$ GeV. In other parameter space where the $ZZ$ or $\gamma \gamma$ signal rate is smaller, the LHC 14 TeV reach is absent, but a resonance shape can be much more dramatically changed. In particular, the $\gamma \gamma$ signal rate can change by $\mathcal{O}(100)\%$. Relevant to such parameter space, we suggest variables that can characterize a general resonance shape. We also illustrate the relevance of the width on the interference by adding non-standard decay modes of the heavy Higgs boson.

    hep-phPRD(2016)·17 citations
11. 11*

    Exploring dynamical gluon mass generation in three dimensions

    John M. Cornwall (Dept. of Physics and Astronomy, UCLA)🇺🇸

    In the d=3 gluon mass problem in pure-glue non-Abelian $SU(N)$ gauge theory we pay particular attention to the observed (in Landau gauge) violation of positivity for the spectral function of the gluon propagator. This causes a large bulge in the propagator at small momentum. Mass is defined through $m^{-2}=\Delta (p=0)$, where $\Delta (p)$ is the scalar function for the gluon propagator in some chosen gauge, it is not a pole mass and is generally gauge-dependent, except in the gauge-invariant Pinch Technique (PT). We truncate the PT equations with a new method called the vertex paradigm that automatically satisfies the QED-like Ward identity relating the 3-gluon PT vertex function with the PT propagator. The mass is determined by a homogeneous Bethe-Salpeter equation involving this vertex and propagator. This gap equation also encapsulates the Bethe-Salpeter equation for the massless scalar excitations, essentially Nambu-Goldstone fields, that necessarily accompany gauge-invariant gluon mass. The problem is to find a good approximate value for $m$ and at the same time explain the bulge, which by itself leads, in the gap equation for the gluon mass, to excessively large values for the mass. Our point is not to give a high-accuracy determination of $m$ but to clarify the way in which the propagator bulge and a fairly accurate estimate of $m$ can co-exist, and we use various approximations that illustrate the underlying mechanisms. The most critical point is to satisfy the Ward identity. In the PT we estimate a gauge-invariant dynamical gluon mass of $m\approx N{g}^2/(2.48\pi )$. We translate these results to the Landau gauge using a background-quantum identity involving a dynamical quantity $\kappa$ such that $m=\kappa m_L$, where $m_L^{-2}\equiv {\Delta }_L(p=0)$. Given our estimates for $m,\kappa$ the relation is fortuitously well-satisfied for $SU(2)$ lattice data.

    hep-phhep-latPRD(2016)·16 citations
12. 12*

    Vectorlike leptons at the Large Hadron Collider

    Nilanjana Kumar🇺🇸 · Stephen P. Martin🇺🇸

    We study the prospects for excluding or discovering vectorlike leptons using multilepton events at the LHC. We consider models in which the vectorlike leptons decay to tau leptons. If the vectorlike leptons are weak isosinglets, then discovery in multilepton states is found to be extremely challenging. For the case that the vectorlike leptons are weak isodoublet, we argue that there may be an opportunity for exclusion for masses up to about 275 GeV by direct searches with existing LHC data at sqrt{s}=8 TeV. We also discuss prospects for exclusion or discovery at the LHC with future sqrt{s}=13 TeV data.

    hep-phPRD(2015)·183 citations
13. 13*

    Towards the Final Word on Neutralino Dark Matter

    Joseph Bramante🇺🇸 · Nishita Desai🇩🇪 · Patrick Fox🇺🇸 · Adam Martin🇺🇸 · Bryan Ostdiek🇺🇸 · Tilman Plehn🇩🇪

    We present a complete phenomenological prospectus for thermal relic neutralinos. Including Sommerfeld enhancements to relic abundance and halo annihilation calculations, we obtain direct, indirect, and collider discovery prospects for all neutralinos with mass parameters $M_1,M_2,|\mu |<4$ TeV, that freeze out to the observed dark matter abundance, with scalar superpartners decoupled. Much of the relic neutralino sector will be uncovered by the direct detection experiments Xenon1T and LZ, as well as indirect detection with CTA. We emphasize that thermal relic higgsinos will be found by next-generation direct detection experiments, so long as $M_{1,2}<4$ TeV. Charged tracks at a 100 TeV hadron collider complement indirect searches for relic winos. Thermal relic bino-winos still evade all planned experiments, including disappearing charged-track searches. However, they can be discovered by compressed electroweakino searches at a 100 TeV collider, completing the full coverage of the relic neutralino surface.

    hep-phPRD(2016)·97 citations
14. 14*

    Scenarios for Gluino Coannihilation

    John Ellis🇬🇧 · Jason L. Evans🇺🇸 · Feng Luo🇨🇭 · Keith A. Olive🇺🇸

    We study supersymmetric scenarios in which the gluino is the next-to-lightest supersymmetric particle (NLSP), with a mass sufficiently close to that of the lightest supersymmetric particle (LSP) that gluino coannihilation becomes important. One of these scenarios is the MSSM with soft supersymmetry-breaking squark and slepton masses that are universal at an input GUT renormalization scale, but with non-universal gaugino masses. The other scenario is an extension of the MSSM to include vector-like supermultiplets. In both scenarios, we identify the regions of parameter space where gluino coannihilation is important, and discuss their relations to other regions of parameter space where other mechanisms bring the dark matter density into the range allowed by cosmology. In the case of the non-universal MSSM scenario, we find that the allowed range of parameter space is constrained by the requirement of electroweak symmetry breaking, the avoidance of a charged LSP and the measured mass of the Higgs boson, in particular, as well as the appearance of other dark matter (co)annihilation processes. Nevertheless, LSP masses $m_{\chi }\lesssim 8$~TeV with the correct dark matter density are quite possible. In the case of pure gravity mediation with additional vector-like supermultiplets, changes to the anomaly-mediated gluino mass and the threshold effects associated with these states can make the gluino almost degenerate with the LSP, and we find a similar upper bound.

    hep-phJHEP(2016)·50 citations
15. 15*

    Dark Matter and Gauge Coupling Unification in Non-SUSY SO(10) Grand Unified Models

    Natsumi Nagata🇺🇸

    The stability of dark matter is naturally explained if there is an additional U(1) symmetry which is spontaneously broken to a discrete symmetry at a high-energy scale. Such a framework is realized in the context of the SO(10) grand unification. In this work, we discuss dark matter models in the non-supersymmetric SO(10) grand unified models in which the stability of dark matter is assured by this mechanism. We find that the requirement of gauge coupling unification with a sufficiently high unification scale to evade the proton decay constraints plays an important role in selecting viable candidates. Some of the dark matter models can be tested in future dark matter direct searches and proton decay experiments.

    hep-phPoS(2015)·3 citations
16. 16*

    Comparing Erlang distribution and Schwinger mechanism on transverse momentum spectra in high energy collisions

    Li-Na Gao🇨🇳 · Fu-Hu Liu🇨🇳

    We study the transverse momentum spectra of J/psi and Upsilon mesons by using two methods: the two-component Erlang distribution and the two-component Schwinger mechanism. The results obtained by the two methods are compared and found to be in agreement with the experimental data of proton-proton (pp), proton-lead (p-Pb), and lead-lead (Pb-Pb) collisions measured by the LHCb and ALICE Collaborations at the large hadron collider (LHC). The related parameters such as the mean transverse momentum contributed by each parton in the first (second) component in the two-component Erlang distribution and the string tension between two partons in the first (second) component in the two-component Schwinger mechanism are extracted.

    hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2016)·8 citations
17. 17*

    Temperature dependence of dimension 6 gluon operators and their effects on Charmonium

    HyungJoo Kim🇰🇷 · Kenji Morita🇯🇵 · Su Houng Lee🇰🇷

    Starting from an earlier representation of the independent dimension 6 gluon operators in terms of color electric and magnetic fields, we estimate their changes near the critical temperature $T_c$ using the temperature dependence of the dimension 4 electric and magnetic condensates extracted from pure gauge theory on the lattice. We then improve the previous QCD sum rules for the $J/\psi$ mass near $T_c$ based on dimension 4 operators, by including the contribution of the dimension 6 operators to the OPE. We find an enhanced stability in the sum rule and confirm that the $J/\psi$ will undergo an abrupt change in the property across $T_c$.

    hep-phnucl-thPRD(2016)·8 citations
18. 18*

    Entropy production by domain wall decay in the NMSSM

    Hironori Hattori🇯🇵 · Tatsuo Kobayashi🇯🇵 · Naoya Omoto🇯🇵 · Osamu Seto🇯🇵

    We consider domain walls in the $Z_3$ symmetric NMSSM. The spontaneous $Z_3$ discrete symmetry breaking produces domain walls, and the stable domain walls are problematic. Thus, we assume the $Z_3$ symmetry is slightly but explicitly broken and the domain walls decay. Such a decay causes a large late-time entropy production. We study its cosmological implications on unwanted relics such as moduli, gravitino, LSP and axion.

    hep-phastro-ph.COPRD(2015)·22 citations
19. 19*

    Y(4260) --> gamma + X(3872) in the diquarkonium picture

    H.-X. Chen🇨🇳 · L. Maiani🇮🇹 · A.D. Polosa🇮🇹 · V. Riquer🇮🇹

    The observed Y(4260)\to \gamma + X(3872) decay is a natural consequence of the diquark-antidiquark description of Y and X resonances. In this note we attempt an estimate of the transition rate, \Gamma_{\rm rad}, by a non-relativistic calculation of the electric dipole term of a diquarkonium bound state. We compute \Gamma_{\rm rad} for generic composition values of the isospin of X and Y. Specializing to I=0 for X(3872), we find \Gamma_{\rm rad}= 496~keV for Y(4260) with I=0 and \Gamma_{\rm rad}= 179~keV for I=1. Combining with BESIII data, we derive upper bounds to B(Y\to J/\Psi+\pi+\pi) and to \Gamma(Y\to \mu^+ \mu^-). We expect to confront these results with forthcoming data from electron-positron and hadron colliders.

    hep-phEPJC(2015)·24 citations
20. 20*

    Constraints on the chiral unitary $\bar{K}N$ amplitude from $\pi \Sigma K^{+}$ photoproduction data

    Maxim Mai🇩🇪

    A chiral unitary approach for antikaon-nucleon scattering in on-shell factorization is studied. We find multiple sets of parameters for which the model describes all existing hadronic data similarly well. We confirm the two-pole structure of the $\Lambda (1405)$. The narrow $\Lambda (1405)$ pole appears at comparable positions in the complex energy plane, whereas the location of the broad pole suffers from a large uncertainty. In the second step, we use a simple model for photoproduction of $K^{+}\pi \Sigma$ off the proton and confront it with the experimental data from the CLAS collaboration. It is found that only a few of the hadronic solutions allow for a consistent description of the CLAS data within the assumed reaction mechanism.

    hep-phnucl-thPoS(2016)·1 citation
21. 21*

    Neutrino-axion-dilaton interconnection

    Stefano Bertolini🇮🇹 · Luca Di Luzio🇮🇹 · Helena Kolešová🇨🇿 · Michal Malinský🇨🇿 · Juan Carlos Vasquez🇮🇹

    We show that a recently proposed framework that provides a simple connection between Majorana neutrinos and an invisible axion in minimal scalar extensions of the standard electroweak model can be naturally embedded in a classically scale-invariant setup. The explicit breaking of the scale invariance à la Coleman-Weinberg generates the Peccei-Quinn and electroweak scales. The spontaneous breaking of the chiral $U(1{)}_{PQ}$ triggers the generation of neutrino masses via Type-II seesaw and, at the same time, provides a dynamical solution to the strong CP problem as well as the axion as a dark matter candidate. The electroweak and neutrino mass scales are obtained via a technically natural ultraweak limit of the singlet scalar interactions. Accordingly, a realistic and perturbatively stable scalar spectrum, possibly in the reach of the LHC, is naturally obtained. A very light pseudodilaton characterizes such a setting. The vacuum stability of the extended setup is discussed.

    hep-phPRD(2016)·14 citations
22. 22*

    $\beta$-function formalism for inflationary models with a non minimal coupling with gravity

    Mauro Pieroni🇫🇷

    We discuss the introduction of a non minimal coupling between the inflaton and gravity in terms of the recently proposed $\beta$-function formalism for inflation\cite{Binetruy:2014zya}. Via a field redefinition we reduce to the case of minimally coupled theories. The universal attractor at strong coupling has a simple explanation in terms of the new field. Generalizations are discussed and the possibility of evading the universal attractor is shown.

    hep-phastro-ph.COgr-qchep-thJCAP(2016)·34 citations
23. 23*

    Double charm production in single- and double-parton scattering

    Antoni Szczurek🇵🇱 · Rafal Maciula🇵🇱

    We discuss production of two pairs of $c\bar{c}$ in proton-proton collisions at the LHC. Both double-parton scattering (DPS) and single-parton scattering (SPS) contributions are included in the analysis. Each step of DPS is calculated within $k_t$-factorization approach which effectively includes some next-to-leading order corrections. The discussed mechanisms unavoidably lead to the production of pairs of mesons: $D_i{D}_j$ (each containing $c$ quarks) or ${\bar{D}}_i{\bar{D}}_j$ (each containing $\bar{c}$ antiquarks). We calculate corresponding differential distribution for $(D^0{D}^0$ + ${\bar{D}}^0{\bar{D}}^0)$ production. Within large theoretical uncertainties the predicted DPS cross section is fairly similar to the cross section measured recently by the LHCb collaboration. We also present first results for the $2\to 4$ single-parton scattering $gg\to c\bar{c}c\bar{c}$ subprocess for the first time fully within the $k_t$-factorization approach. In this calculation we have used an off-shell matrix element squared calculated using recently developed techniques. The results are compared with our earlier result obtained within the collinear approach. Only slightly larger cross sections are obtained than in the case of the collinear approach but still the SPS mechanism contribution is much smaller than the DPS one. Inclusion of transverse momenta of gluons entering the hard process leads to a much stronger azimuthal decorrelation between $cc$ and $\bar{c}\bar{c}$ than in the collinear-factorization approach. A comparison to predictions of double parton scattering (DPS) results and the LHCb data strongly suggests that the assumption of two fully independent DPS ($gg\to c\bar{c}\otimes gg\to c\bar{c}$) may be too approximate.

    hep-ph0 citations
24. 24*

    Quark-flavour violation in $h^0\to b\bar{b}$ in the MSSM at one-loop level

    E. Ginina🇦🇹 · A. Bartl🇦🇹 · H. Eberl🇦🇹 · K. Hidaka🇯🇵 · W. Majerotto🇦🇹

    We compute the width of the decay $h^0$ (125 GeV) $\to b\bar{b}$ at next-to-leading order in the general MSSM with quark-flavour violation (QFV). We study the effect of mixing between the second and the third generation of squarks, taking into account the constraints on QFV from B-meson data. We discuss the renormalisation of the process as well as the resummation of the bottom Yukawa coupling at large $\tan \beta$. We show numerical results on the decay width $\Gamma (h^0\to b\bar{b})$ as a function of the involved QFV parameters and compare them with the corresponding width in the Standard Model.

    hep-phPoS(2015)·2 citations
25. 25*

    Double-scattering mechanism of production of two ${\rho }^0$ mesons in ultraperipheral, ultrarelativistic heavy ion collisions

    Antoni Szczurek🇵🇱 · Mariola Klusek-Gawenda🇵🇱

    We study, for the first time, differential distributions for two ${\rho }^0$ meson production in exclusive ultraperipheral, ultrarelativistic heavy ion collisions via a double-scattering mechanism. The calculations are done in the impact parameter space. The cross section for $\gamma A\to {\rho }^{0}A$ is parametrized based on an existing model. Smearing of ${\rho }^0$ masses is taken into account. The results of calculations for single and double-${\rho }^0$ production are compared to experimental data at the RHIC and LHC energies. The mechanism considered gives a significant contribution to the $AA\to AA{\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ reaction. Some observables related to charged pions are presented too. We compare results of our calculations with the STAR collaboration results for four charged pion production.

    hep-phPoS(2015)·0 citations
26. 26*

    Higgs production within $k_t$-factorization with unintegrated gluon distributions

    Antoni Szczurek🇵🇱

    We present differential cross sections for Higgs boson and/or two-photon production from intermediate (virtual) Higgs boson within the formalism of $k_t$-factorization. Resulting distributions for two photons from the Higgs boson are compared with recent ATLAS collaboration data. In contrast to a recent calculation the leading order $gg\to H$ contribution is rather small compared to the ATLAS experimental data ($\gamma \gamma$ transverse momentum and rapidity distributions). We include also higher-order contribution $gg\to H(\to \gamma \gamma )g$, $gg\to gHg$ and the contribution of the $W^{+}{W}^{-}$ and $Z^0{Z}^0$ exchanges. The $gg\to Hg$ mechanism gives a similar contribution as the $gg\to H$ mechanism. We argue that there is almost no double counting when adding $gg\to H$ and $gg\to Hg$ contributions due to different topology of corresponding Feynman diagrams. The final sum is comparable with the ATLAS two-photon data.

    hep-phPoS(2015)·0 citations
27. 27*

    Comparing mesons and W_L W_L TeV-resonances

    Antonio Dobado🇪🇸 · Rafael L. Delgado🇪🇸 · Felipe J. Llanes-Estrada (speaker, U. Complutense de Madrid)🇪🇸 · Domenec Espriu (U. Barcelona)🇪🇸

    Tantalizing LHC hints suggest that resonances of the Electroweak Symmetry Breaking Sector might exist at the TeV scale. We recall a few key meson-meson resonances in the GeV region that could have high-energy analogues which we compare, as well as the corresponding unitarized effective theories describing them. While detailed dynamics may be different, the constraints of unitarity, causality and global-symmetry breaking, incorporated in the Inverse Amplitude Method, allow to carry some intuition over to the largely unmeasured higher energy domain. If the 2 TeV ATLAS excess advances one such new resonance, this could indicate an anomalous q qbar W coupling.

    hep-phBled Workshops Phys.(2015)·4 citations
28. 28*

    Radiative origin of neutrino masses

    D. Aristizabal Sierra🇧🇪

    Mechanisms for Majorana neutrino mass generation can be classified according to the level at which the Weinberg operator is generated. The different possibilities can be sorted in "canonical" tree level and loop-induced realizations, the latter being motivated by their potential experimental testability. Here we discuss the one- and two-loop cases, paying special attention to systematic classification schemes which aim at building a full picture of neutrino mass generation.

    hep-phActa Phys.Polon.B(2015)·1 citation
29. 29*

    Wavefunctions on magnetized branes in the conifold

    Hiroyuki Abe🇯🇵 · Akane Oikawa🇯🇵 · Hajime Otsuka🇯🇵

    We study wavefunctions on D$7$-branes with magnetic fluxes in the conifold. Since some supersymmetric embeddings of D-branes on the $Ad{S}_5\times T^{1,1}$ geometry are known, we consider one of the embeddings, especially the spacetime filling D$7$-branes in which (a part of) the standard model is expected to be realized. The explicit form of induced metric on the D$7$-branes allows us to solve the Laplace and Dirac equations to evaluate matter wavefunctions in extra dimensions analytically. We find that the zero-mode wavefunctions can be localized depending on the configuration of magnetic fluxes on D$7$-branes, and show some phenomenological aspects.

    ↳ hep-thhep-phJHEP(2016)·6 citations
30. 30*

    BB interactions with static bottom quarks from Lattice QCD

    Pedro Bicudo🇵🇹 · Krzysztof Cichy🇩🇪 · Antje Peters🇩🇪 · Marc Wagner🇩🇪

    The isospin, spin and parity dependent potential of a pair of $B$ mesons is computed using Wilson twisted mass lattice QCD with two flavours of degenerate dynamical quarks. The $B$ meson is addressed in the static-light approximation, i.e.\ the $b$ quarks are infinitely heavy. From the results of the $BB$ meson-meson potentials, a simple rule can be deduced stating which isospin, spin and parity combinations correspond to attractive and which to repulsive forces. We provide fits to the ground state potentials in the attractive channels and discuss the potentials in the repulsive and excited channels. The attractive channels are most important since they can possibly lead to a bound four-quark state, i.e.\ a $\bar{b}\bar{b}ud$ tetraquark. Using these attractive potentials in the Schrödinger equation, we find indication for such a tetraquark state of two static bottom antiquarks and two light $u/d$ quarks with mass extrapolated down to the physical value.

    ↳ hep-lathep-phPRD(2016)·127 citations
31. 31*

    Starobinsky-like two-field inflation

    Sho Kaneda🇯🇵 · Sergei V. Ketov🇯🇵

    We consider an extension of the Starobinsky model, whose parameters are functions of an extra scalar field. Our motivation is to test the robustness (or sensitivity) of the Starobinsky inflation against mixing scalaron with another (matter) scalar field. We find that the extended Starobinsky model is (classically) equivalent to the two-field inflation, with the scalar potential having a flat direction. For the sake of fully explicit calculations, we perform a numerical scan of the parameter space. Our numerical calculations support the viability of the Starobinsky-like two-field inflation for the certain range of its parameters, which are characterized by the scalar index $n_s=0.96\pm 0.01$, the tensor-to-scalar ratio $r<0.06$, and small running of the scalar index at $|{\alpha }_s|<0.05$.

    ↳ hep-thgr-qchep-phEPJC(2016)·74 citations
32. 32*

    Schwinger-Dyson Study for Walking/Conformal Dynamics with IR Cutoffs

    Kohtaroh Miura🇯🇵 · Kei-ichi Nagai🇯🇵 · Akihiro Shibata🇯🇵

    Motivated by recent progress on many flavor QCD on a lattice, we investigate conformal/walking dynamics by using Schwinger-Dyson (SD) equation within an improved ladder approximation for two-loop running coupling. By numerically solving the SD equation, we obtain a pole mass $m_p$, pion decay constant $f_{\pi }$, and investigate the chiral symmetry breaking and mass anomalous dimension ${\gamma }_m$ in the presence of IR cutoffs ${\Lambda }_{\mathrm{IR}}$. We find that the chiral symmetry breaking is suppressed \ if IR cutoff ${\Lambda }_{\mathrm{IR}}$ becomes larger than the critical \ value near the dynamical mass (${\Lambda }_{\mathrm{IR}}$ $\simeq m_D$) In the conformal phase the ${\gamma }_m$ is strongly suppressed by IR cutoffs for ${\Lambda }_{\mathrm{IR}}$ $\simeq m_p$. We, then, obtain finite size hyperscaling (FSS) relation by adapting a linearized approximation for the SD equation, and examine the ${\gamma }_m$ The results offer valuable insight and suggestion for analyses in lattice gauge theories.

    ↳ hep-lathep-ph1 citation
33. 33*

    On-shell diagrammatics and the perturbative structure of planar gauge theories

    Paolo Benincasa🇪🇸

    We discuss the on-shell diagrammatic representation of theories less special than maximally supersymmetric Yang-Mills. In particular, we focus on planar $\mathcal{N}\le 2$ gauge theories, including pure Yang-Mills. For such a class of theories, the on-shell diagrammatics is endowed with a decoration which carries the information on the helicity of the coherent states. In the first part of the paper we extensively discuss the properties of this decorated diagrammatics. Particular relevance have the helicity flows that the decoration induces on the diagrams, which allows to identify the different classes of singularities and, consequentely, the singularity structure of the on-shell processes. The second part of the paper establishes a link between the decorated on-shell diagrammatics and the scattering amplitudes for the theories under examination. We prove that an all-loop recursion relation at integrand level holds also for $\mathcal{N}=1,2$, while for $\mathcal{N}=0$ we are able to set up a preliminary analysis at one loop. In both supersymmetric and non-supersymmetric case, the treatment of the forward limit is subtle. We provide a fully on-shell analysis of it which is crucial for the proof of the all-loop recursion relation and for the analysis of pure Yang-Mills.

    ↳ hep-thhep-ph38 citations
34. 34*

    Non-minimal coupling in Higgs-Yukawa model with asymptotically safe gravity

    Kin-ya Oda🇯🇵 · Masatoshi Yamada🇯🇵

    We study the fixed point structure of the Higgs-Yukawa model, with its scalar being non-minimally coupled to the asymptotically safe gravity, using the functional renormalization group. We have obtained the renormalization group equations for the cosmological and Newton constants, the scalar mass-squared and quartic coupling constant, and the Yukawa and non-minimal coupling constants, taking into account all the scalar, fermion, and graviton loops. We find that switching on the fermionic quantum fluctuations makes the non-minimal coupling constant irrelevant around the Gaussian-matter fixed point with the asymptotically safe gravity.

    ↳ hep-thgr-qchep-phClass.Quant.Grav.(2016)·155 citations
35. 35*

    Probing strongly coupled anisotropic plasmas from higher curvature gravity

    Viktor Jahnke🇧🇷 · Anderson Seigo Misobuchi🇧🇷

    We consider five-dimensional AdS-axion-dilaton gravity with a Gauss-Bonnet term and use a black brane solution displaying spatial anisotropy as the gravity dual of a strongly coupled anisotropic plasma. We compute several observables relevant to the study of the plasma, namely, the drag force, the jet quenching parameter, the quarkonium potential and the thermal photon production. The effects of higher derivative corrections and of the anisotropy are discussed and compared with previous results.

    ↳ hep-thhep-phnucl-thEPJC(2016)·22 citations
36. 36*

    Matter-Sector Lorentz Violation in Binary Pulsars

    Ross J. Jennings🇺🇸 · Jay D. Tasson🇺🇸 · Shun Yang🇺🇸

    Violations of local Lorentz invariance in the gravitationally coupled matter sector have yet to be sought in strong-gravity systems. We present the implications of matter-sector Lorentz violation for orbital perturbations in pulsar systems and show that the analysis of pulsar data can provide sensitivities to these effects that exceed the current reach of solar system and laboratory tests by several orders of magnitude.

    ↳ gr-qchep-phPRD(2015)·27 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.