Fri·Oct 9, 2015Friday·October 9, 2015

1. 01*

   The sunrise integral around two and four space-time dimensions in terms of elliptic polylogarithms

   Luise Adams🇩🇪 · Christian Bogner🇩🇪 · Stefan Weinzierl🇩🇪

   In this talk we discuss the solution for the sunrise integral around two and four space-time dimensions in terms of a generalised elliptic version of the multiple polylogarithms. In two space-time dimensions we obtain a sum of three elliptic dilogarithms. The arguments of the elliptic dilogarithms have a nice geometric interpretation. In four space-time dimensions the sunrise integral can be expressed with the ${ϵ}^0$- and ${ϵ}^1$-solution around two dimensions, mass derivatives thereof and simpler terms.

   hep-phActa Phys.Polon.B(2015)·10 citations
2. 02*

   Forward-backward correlations with strange particles in PYTHIA

   Igor Altsybeev🇷🇺 · Grigory Feofilov🇷🇺 · Ewen Lawson Gillies🇬🇧

   We present studies of strange particle yields and correlations in $pp$ collisions in the PYTHIA8 event generator by studying forward-backward correlations. Several key processes that give rise to these correlative effects are identified and manipulated to probe the fundamental properties of strange particle emitting sources. The sensitivity of strange particle production and correlations to PYTHIA's multiparton interaction, color reconnection, and explicit strangeness suppression are shown.

   hep-phJ.Phys.Conf.Ser.(2016)·4 citations
3. 03*

   Models of Neutrino Mass, Mixing and CP Violation

   Stephen F. King🇬🇧

   In this topical review we argue that neutrino mass and mixing data motivates extending the Standard Model to include a non-Abelian discrete flavour symmetry in order to accurately predict the large leptonic mixing angles and CP violation. We begin with an overview of the Standard Model puzzles, followed by a description of some classic lepton mixing patterns. Lepton mixing may be regarded as a deviation from tri-bimaximal mixing, with charged lepton corrections leading to solar mixing sum rules, or tri-maximal lepton mixing leading to atmospheric mixing rules. We survey neutrino mass models, using a roadmap based on the open questions in neutrino physics. We then focus on the seesaw mechanism with right-handed neutrinos, where sequential dominance (SD) can account for large lepton mixing angles and CP violation, with precise predictions emerging from constrained SD (CSD). We define the flavour problem and discuss progress towards a theory of flavour using GUTs and discrete family symmetry. We classify models as direct, semidirect or indirect, according to the relation between the Klein symmetry of the mass matrices and the discrete family symmetry, in all cases focussing on spontaneous CP violation. Finally we give two examples of realistic and highly predictive indirect models with CSD, namely an A to Z of flavour with Pati-Salam and a fairly complete $A_4\times SU(5)$ SUSY GUT of flavour, where both models have interesting implications for leptogenesis.

   hep-phJ.Phys.G(2015)·208 citations
4. 04*

   Implications of unitarity and gauge invariance for simplified dark matter models

   Felix Kahlhoefer (DESY)🇩🇪 · Kai Schmidt-Hoberg (DESY)🇩🇪 · Thomas Schwetz (KIT)🇩🇪 · Stefan Vogl (Stockholm & KIT)🇸🇪

   We show that simplified models used to describe the interactions of dark matter with Standard Model particles do not in general respect gauge invariance and that perturbative unitarity may be violated in large regions of the parameter space. The modifications necessary to cure these inconsistencies may imply a much richer phenomenology and lead to stringent constraints on the model. We illustrate these observations by considering the simplified model of a fermionic dark matter particle and a vector mediator. Imposing gauge invariance then leads to strong constraints from dilepton resonance searches and electroweak precision tests. Furthermore, the new states required to restore perturbative unitarity can mix with Standard Model states and mediate interactions between the dark and the visible sector, leading to new experimental signatures such as invisible Higgs decays. The resulting constraints are typically stronger than the 'classic' constraints on DM simplified models such as monojet searches and make it difficult to avoid thermal overproduction of dark matter.

   hep-phastro-ph.COJHEP(2016)·277 citations
5. 05*

   Single- and central-diffractive production of open charm and bottom mesons at the LHC

   Marta Luszczak🇵🇱 · Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

   We discuss diffractive production of open charm and bottom mesons at the LHC. The differential cross sections for single- and central-diffractive mechanisms for $c\bar{c}$ and $b\bar{b}$ pair production are calculated in the framework of the Ingelman-Schlein model corrected for absorption effects. The LO gluon-gluon fusion and quark-antiquark anihilation partonic subprocesses are taken into consideration, which are calculated within standard collinear approximation. The extra corrections from reggeon exchanges are taken into account. The hadronization of charm and bottom quarks is taken into account by means of fragmentation functions. Predictions for single- and central-diffractive production in the case of $D$ and $B$ mesons, as well as $D\bar{D}$ pairs are presented, including detector acceptance of the ATLAS, CMS and LHCb Collaborations.

   hep-phActa Phys.Polon.Supp.(2015)·0 citations
6. 06*

   The top quark right coupling in the tbW-vertex

   Gabriel A. González-Sprinberg🇺🇾 · Jordi Vidal🇪🇸

   The most general parametrization of the $tbW$ vertex includes a right coupling $V_R$ that is zero at tree level in the standard model. This quantity may be measured at the Large Hadron Collider where the physics of the top decay is currently investigated. This coupling is present in new physics models at tree level and/or through radiative corrections, so its measurement can be sensitive to non standard physics. In this paper we compute the leading electroweak and QCD contributions to the top $V_R$ coupling in the standard model. This value is the starting point in order to separate the standard model effects and, then, search for new physics. We also propose observables that can be addressed at the LHC in order to measure this coupling. These observables are defined in such a way that they do not receive tree level contributions from the standard model and are directly proportional to the right coupling. Bounds on new physics models can be obtained through the measurements of these observables.

   hep-phEPJC(2015)·11 citations
7. 07*

   Naturalness of effective theories in Wilsonian approach

   Tomasz Krajewski🇵🇱 · Zygmunt Lalak🇵🇱

   We have computed Wilsonian effective action in a simple model containing scalar field with quartic self-coupling which interacts via Yukawa coupling with a Dirac fermion. The model is invariant under a chiral parity operation, which can be spontaneously broken by a vev of the scalar field. We have computed explicitly Wilsonian running of relevant parameters which makes it possible to discuss in a consistent manner the issue of fine-tuning and stability of the scalar potential. This has been compared with the typical picture based on Gell-Mann-Low running. Since Wilsonian running includes automatically integration out of heavy degrees of freedom, the running differs markedly from the Gell-Mann-Low version. However, similar behavior can be observed: scalar mass squared parameter and the quartic coupling can change sign from a positive to a negative one due to running which causes spontaneous symmetry breaking or an instability in the renormalizable part of the potential for a given range of scales. As for the issue of fine-tuning, since in the Wilsonian approach power-law terms are not subtracted, one can clearly observe the quadratic sensitivity of fine-tuning measure to the change of the cut-off scale.

   hep-phPoS(2015)·3 citations
8. 08*

   Dark matter and muon $(g-2)$ in local $U(1{)}_{L_{\mu }-L_{\tau }}$-extended Ma Model

   Seungwon Baek🇰🇷

   We consider right-handed neutrino dark matter $N_1$ in local $U(1{)}_{L_{\mu }-L_{\tau }}$-extended Ma model. With the light $U(1{)}_{\mu -\tau }$ gauge boson ($m_{Z^{\prime }}\sim \mathcal{O}(100)$ MeV) and small $U(1{)}_{\mu -\tau }$ gauge coupling ($g_{Z^{\prime }}\sim 10^{-4}-10^{-3}$) which can accommodate the muon $(g-2)$ anomaly and is still allowed by other experimental constraints, we show that we can get correct relic density of dark matter for wide range of dark matter mass ($M_1\sim 10-100$ GeV), although the gauge coupling constant $g_{Z^{\prime }}$ is small. This is due to the fact that the annihilation cross section of dark matter pair is enhanced by $M_1^4/m_{Z^{\prime }}^4$ in the processes $N_1{N}_1\to Z^{\prime }{Z}^{\prime }$ or $N_1{N}_1\to Z^{\prime }{H}_2$. We also consider the constraints from direct detection, collider searches.

   hep-phPLB(2016)·71 citations
9. 09*

   Semi-Annihilating Wino-Like Dark Matter

   Andrew P. Spray🇦🇺 · Yi Cai🇦🇺

   Semi-annihilation is a generic feature of dark matter theories with symmetries larger than Z_2. We explore a model based on a Z_4-symmetric dark sector comprised of a scalar singlet and a "wino"-like fermion SU(2)_L triplet. This is the minimal example of semi-annihilation with a gauge-charged fermion. We study the interplay of the Sommerfeld effect in both annihilation and semi-annihilation channels. The modifications to the relic density allow otherwise-forbidden regions of parameter space and can substantially weaken indirect detection constraints. We perform a parameter scan and find that the entire region where the model comprises all the observed dark matter is accessible to current and planned direct and indirect searches.

   hep-phPoS(2015)·1 citation
10. 10*

    Effective Field Theories and Lattice QCD

    C. Bernard🇺🇸

    I describe some of the many connections between lattice QCD and effective field theories, focusing in particular on chiral effective theory, and, to a lesser extent, Symanzik effective theory. I first discuss the ways in which effective theories have enabled and supported lattice QCD calculations. Particular attention is paid to the inclusion of discretization errors, for a variety of lattice QCD actions, into chiral effective theory. Several other examples of the usefulness of chiral perturbation theory, including the encoding of partial quenching and of twisted boundary conditions, are also described. In the second part of the talk, I turn to results from lattice QCD for the low energy constants of the two- and three-flavor chiral theories. I concentrate here on mesonic quantities, but the dependence of the nucleon mass on the pion mass is also discussed. Finally I describe some recent preliminary lattice QCD calculations by the MILC Collaboration relating to the three-flavor chiral limit.

    hep-phhep-latPoS(2015)·9 citations
11. 11*

    Neutrinos secretly converting to lighter particles to please both KATRIN and the cosmos

    Yasaman Farzan🇮🇷 · Steen Hannestad🇩🇰

    Within the framework of the Standard Model of particle physics and standard cosmology, observations of the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) set stringent bounds on the sum of the masses of neutrinos. If these bounds are satisfied, the upcoming KATRIN experiment which is designed to probe neutrino mass down to $\sim 0.2$ eV will observe only a null signal. We show that the bounds can be relaxed by introducing new interactions for the massive active neutrinos, making neutrino masses in the range observable by KATRIN compatible with cosmological bounds. Within this scenario, neutrinos convert to new stable light particles by resonant production of intermediate states around a temperature of $T\sim$ keV in the early Universe, leading to a much less pronounced suppression of density fluctuations compared to the standard model.

    hep-phastro-ph.COJCAP(2016)·48 citations
12. 12*

    New fixed points of the renormalisation group for two-body scattering

    M. C. Birse🇬🇧 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪

    We outline a separable matrix ansatz for the potentials in effective field theories of nonrelativistic two-body systems with short-range interactions. We use this ansatz to construct new fixed points of the renormalisation-group equation for these potentials. New fixed points indicate a much richer structure than previously recognized in the RG flows of simple short-range potentials.

    hep-phnucl-thEPJA(2016)·5 citations
13. 13*

    Effective field theories and pseudo-observables in the quest for physics beyond the Standard Model

    Raquel Gomez-Ambrosio🇮🇹

    We discuss briefly the kappa framework, proposed originally as a test for the Higgs couplings of the Standard Model (SM). Further, we discuss a generalization of this idea in terms of effective field theory. We sketch how to add dimension 6 operators to the SM Lagrangian and the renormalization process. Finally we show how to study the amplitudes of the resulting model at next-to-leading order and discuss possible experimental approaches.

    hep-phhep-thPoS(2015)·2 citations
14. 14*

    Pseudo-scalar Higgs Boson Production at Threshold N${}^3$LO and N${}^3$LL QCD

    Taushif Ahmed🇮🇳 · M. C. Kumar🇮🇳 · Prakash Mathews🇮🇳 · Narayan Rana🇮🇳 · V. Ravindran🇮🇳

    We present the first results on the production of pseudo-scalar through gluon fusion at the LHC to N${}^3$LO in QCD taking into account only soft gluon effects. We have used the effective Lagrangian that describes the coupling of pseudo-scalar with the gluons in the large top quark mass limit. We have used recently available quantities namely the three loop pseudo-scalar form factor and the third order universal soft function in QCD to achieve this. Along with the fixed order results, we also present the process dependent resummation coefficient for threshold resummation to N${}^3$LL in QCD. Phenomenological impact of these threshold N${}^3$LO corrections to pseudo-scalar production at the LHC is presented and their role to reduce the renormalisation scale dependence is demonstrated.

    hep-phhep-exEPJC(2016)·38 citations
15. 15*

    $\mu \to e\gamma$ in a supersymmetric radiative neutrino mass model

    Raghavendra Srikanth Hundi🇮🇳

    We have considered a supersymmetric version of the inert Higgs doublet model, whose motivation is to explain smallness of neutrino masses and existence of dark matter. In this supersymmetric model, due to the presence of discrete symmetries, neutrinos acquire masses at loop level. After computing these neutrino masses, in order to fit the neutrino oscillation data, we have shown that by tuning some supersymmetry breaking soft parameters of the model, neutrino Yukawa couplings can be unsuppressed. In the above mentioned parameter space, we have computed branching ratio of the decay $\mu \to e\gamma$. To be consistent with the current experimental upper bound on $Br(\mu \to e\gamma )$, we have obtained constraints on the right-handed neutrino mass of this model.

    hep-phPRD(2016)·7 citations
16. 16*

    Towards an assessment of the ATLAS data on the branching ratio Gamma(Lambda_b(0) -> psi(2S) Lambda(0))/Gamma(Lambda_b(0) -> J/psi Lambda(0))

    Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jurgen G. Korner🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Pietro Santorelli🇮🇹

    Recently the ATLAS Collaboration at CERN reported on the measurement of the branching ratio R(Lambda_b) = Gamma(Lambda_b(0) -> psi(2S) Lambda(0))/Gamma(Lambda_b(0) -> J/psi Lambda(0)). The measured branching ratio R(Lambda_b) = 0.501 pm 0.033$ (stat) pm 0.019 (syst) was found to be lower than the covariant quark model prediction of R(Lambda_b) = 0.8 pm 0.1 calculated by us recently. We present a detailed analysis of the branching ratio R(Lambda_b) using a model-independent framework for the heavy-to-light form factors based on results from our previos papers.

    hep-phPRD(2015)·15 citations
17. 17*

    Impact of Dark Matter Direct and Indirect Detection on Simplified Dark Matter Models

    Giorgio Arcadi🇫🇷 · Yann Mambrini🇫🇷 · Mathias Pierre🇫🇷

    We discuss simple extensions of the Standard Model featuring a (fermionic) stable DM candidate interacting with SM fermions through a $Z^{{}^{\prime }}$ mediator. These kind of models offer a wide phenomenology but result, at the same time, particularly manageable, given the limited number of free-parameters, and offer a broad LHC phenomenology. We will discuss the impact Direct and Indirect Dark Matter searches, assuming the latter to be thermal WIMPs. We will show in particular that the combinations of the limits on the DM Spin Independent and Spin Dependent scattering cross-section on nuclei already exclude large portions of the parameter space favored by DM relic density, in particular if, in addition, a DM Indirect signal, like the Galactic Center gamma-ray excess is required.

    hep-phPoS(2015)·4 citations
18. 18*

    Observable Gravitational Waves From Kinetically Modified Non-Minimal Inflation

    C. Pallis🇪🇸

    We consider Supersymmetric (SUSY) and non-SUSY models of chaotic inflation based on the simplest power-law potential with exponents n=2 and 4. We propose a convenient non-minimal coupling to gravity and a non-minimal kinetic term which ensure, mainly for n=4, inflationary observables favored by the BICEP2/Keck Array and Planck results. Inflation can be attained for subplanckian inflaton values with the corresponding effective theories retaining the perturbative unitarity up to the Planck scale.

    hep-phastro-ph.COhep-thPoS(2015)·6 citations
19. 19*

    Large Two-loop Effects in the Higgs Sector as New Physics Probes

    Sichun Sun🇨🇳

    We consider a simple Higgs portal model in beyond the standard model scenario: an extra real gauge singlet scalar that couples to the Higgs. We calculate the higher-loop corrections to the cross section of the Higgsstrahlung process $e^{+}{e}^{-}\to Zh$, along with the tri-Higgs coupling and the wave-function renormalization. We find noticeable contribution to the total Higgsstrahlung cross section, especially coming from two-loop diagrams. We also find that the correction to the tri-Higgs coupling is complex when this extra scalar is lighter than half of the center of mass energy. It indicates a new source of CP violation. In the region of this extra scalar being lighter than a couple of hundreds of GeVs, we argue that the higher-loop calculation is a more reliable approach than the effective field theory calculation.

    hep-ph4 citations
20. 20*

    LHC diboson excesses as an evidence for a heavy WW resonance

    B.A. Arbuzov🇷🇺 · I.V. Zaitsev🇷🇺

    Recently reported diboson excesses at LHC are interpreted to be connected with heavy $WW$ resonance with weak isotopic spin 2. The resonance appears due to the wouldbe anomalous triple interaction of the weak bosons, which is defined by well-known coupling constant $\lambda$. We obtain estimates for the effect, which qualitatively agree with ATLAS data. Effects are predicted in inclusive production of $W^{+}{W}^{+},W^{+}(Z,\gamma ),W^{+}{W}^{-},(Z,\gamma )(Z,\gamma ),W^{-}(Z,\gamma ),W^{-}{W}^{-}$ resonances with $M_R\simeq 2TeV$, which could be reliably checked at the upgraded LHC with $\sqrt{s}=13TeV$. In the framework of an approach to the spontaneous generation of of the triple anomalous interaction its coupling constant is estimated to be $\lambda =-0.017\pm 0.005$ in an agreement with existing restrictions.

    hep-ph3 citations
21. 21*

    Charm and beauty quark masses in the MMHT2014 global PDF analysis

    L. A. Harland-Lang🇬🇧 · A. D. Martin🇬🇧 · P. Motylinski🇬🇧 · R.S. Thorne🇬🇧

    We investigate the variation in the MMHT2014 PDFs when we allow the heavy quark masses $m_c$ and $m_b$ to vary away from their default values. We make PDF sets available in steps of $\Delta m_c=0.05\mathrm{GeV}$ and $\Delta m_b=0.25\mathrm{GeV}$, and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy quark data, and the inclusive data, have a slight preference for lower masses than our default values. We provide PDF sets with 3 and 4 active quark flavours, as well as the standard value of 5 flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the $\overline{\mathrm{MS}}$ definition.

    hep-phEPJC(2016)·53 citations
22. 22*

    Methods for Higgs boson production at N${}^3$LO

    Jens Hoff🇩🇪

    We discuss methods for the calculation of the total partonic Higgs boson production cross section via gluon fusion and the result for the contribution that stems from two quarks of different flavor in the initial state. Our calculation is exact in the Higgs boson mass and the partonic center-of-mass energy. The result is expressed in terms of iterated integrals, some of which are Harmonic Polylogarithms, whereas others are new iterated integrals. We comment on the methods relevant for the reduction to scalar integrals and new types of function that appear in the final result.

    hep-phNucl.Part.Phys.Proc.(2016)·0 citations
23. 23*

    Phenomenology of semileptonic B-meson decays with form factors from lattice QCD

    Daping Du🇺🇸 · A. X. El-Khadra🇺🇸 · Steven Gottlieb🇺🇸 · A. S. Kronfeld🇺🇸 · J. Laiho🇺🇸 · E. Lunghi🇺🇸 · R. S. Van de Water🇺🇸 · Ran Zhou🇺🇸

    We study the exclusive semileptonic $B$-meson decays $B\to K(\pi ){\ell }^{+}{\ell }^{-}$, $B\to K(\pi )\nu \bar{\nu }$, and $B\to \pi \tau \nu$, computing observables in the Standard model using the recent lattice-QCD results for the underlying form factors from the Fermilab Lattice and MILC Collaborations. These processes provide theoretically clean windows into physics beyond the Standard Model because the hadronic uncertainties are now under good control for suitably binned observables. For example, the resulting partially integrated branching fractions for $B\to \pi {\mu }^{+}{\mu }^{-}$ and $B\to K{\mu }^{+}{\mu }^{-}$ outside the charmonium resonance region are 1-2$\sigma$ higher than the LHCb Collaboration's recent measurements, where the theoretical and experimental errors are commensurate. The combined tension is 1.7$\sigma$. Combining the Standard-Model rates with LHCb's measurements yields values for the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{td}|=7.45(69)\times 10^{-3}$, $|V_{ts}|=35.7(1.5)\times 10^{-3}$, and $|V_{td}/V_{ts}|=0.201(20)$, which are compatible with the values obtained from neutral $B_{(s)}$-meson oscillations and have competitive uncertainties. Alternatively, taking the CKM matrix elements from unitarity, we constrain new-physics contributions at the electroweak scale. The constraints on the Wilson coefficients $\mathrm{Re}(C_9)$ and $\mathrm{Re}(C_{10})$ from $B\to \pi {\mu }^{+}{\mu }^{-}$ and $B\to K{\mu }^{+}{\mu }^{-}$ are competitive with those from $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$, and display a 2.0$\sigma$ tension with the Standard Model. Our predictions for $B\to K(\pi )\nu \bar{\nu }$ and $B\to \pi \tau \nu$ are close to the current experimental limits.

    hep-phhep-exhep-latPRD(2016)·131 citations
24. 24*

    Constraints on Abelian Extensions of the Standard Model from Two-Loop Vacuum Stability and $U(1{)}_{B-L}$

    Claudio Coriano🇮🇹 · Luigi Delle Rose🇮🇹 · Carlo Marzo🇮🇹

    We present a renormalization group study of the scalar potential in a minimal $U(1{)}_{B-L}$ extension of the Standard Model involving one extra heavier Higgs and three heavy right-handed neutrinos with family universal B-L charge assignments. We implement a type-I seesaw for the masses of the light neutrinos of the Standard Model. In particular, compared to a previous study, we perform a two-loop extension of the evolution, showing that two-loop effects are essential for the study of the stability of the scalar potential up to the Planck scale. The analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one-loop matching conditions at the electroweak scale. By requiring the stability of the potential up to the Planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the Higgs sector are identified.

    hep-phhep-thJHEP(2016)·53 citations
25. 25*

    Family symmetries and CP

    I. de Medeiros Varzielas🇬🇧

    CP-odd invariants, independent of basis and valid for any choice of CP transformation are a powerful tool in the study of CP. They are particularly convenient to study the CP properties of models with family symmetries. After interpreting the consequences of adding specific CP symmetries to a Lagrangian invariant under $\Delta (27)$, I use the invariant approach to systematically study Yukawa-like Lagrangians with an increasing field content in terms of $\Delta (27)$ representations. Included in the Lagrangians studied are models featuring explicit CP violation with calculable phases (referred to as explicit geometrical CP violation) and models that automatically conserve CP, despite having all the $\Delta (27)$ representations.

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

    Double Higgs boson production in the Standard Model with extra scalar particles

    E. V. Zhemchugov🇷🇺

    Three extensions of the scalar sector of the Standard Model are considered: one extra isosinglet, one extra isotriplet, two extra isotriplets (the Georgi-Machacek model). Double Higgs boson production cross section is calculated in all these extensions. Bounds from electroweak precision observables, signal strength measurements and custodial symmetry violation are estimated.

    hep-ph1 citation
27. 27*

    Baryon chiral perturbation theory extended beyond the low-energy region

    E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪 · De-Liang Yao🇩🇪

    We consider an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. The applicability of this approach for higher energies is restricted to small scattering angles, i.e. the kinematical region, where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power counting and to exploit the freedom of the choice of the renormalization condition for loop diagrams. We generalize the extended on-mass-shell scheme for the one-nucleon sector of baryon chiral perturbation theory by choosing a sliding scale, that is we expand the physical amplitudes around kinematical points beyond the threshold. This requires the introduction of complex-valued renormalized coupling constants which can be either extracted from experimental data, or calculated using the renormalization group evolution of coupling constants fixed in threshold region.

    hep-phEPJC(2015)·18 citations
28. 28*

    Parameterizing the SFC Baryogenesis Model

    Daniela Kirilova🇷🇺 · Mariana Panayotova🇧🇬

    We have numerically explored the Scalar Field Condensate baryogenesis model for numerous sets of model's parameters, within their natural range of values. We have investigated the evolution of the baryon charge carrying field, the evolution of the baryon charge contained in the scalar field condensate and the final value of the generated baryon charge on the model's parameters: the gauge coupling constant $\alpha$, the Hubble constant at the inflationary stage $H_I$, the mass $m$, the self-coupling constants ${\lambda }_i$.

    hep-phastro-ph.COAdv.Astron.(2015)·0 citations
29. 29*

    Semileptonic ${\Lambda }_c$ decay to $\nu l^{+}$ and $\Lambda (1405)$

    N. Ikeno🇯🇵 · E. Oset🇪🇸

    We study the semileptonic decay of ${\Lambda }_c$ to $\nu l^{+}$ and $\Lambda (1405)$, where the $\Lambda (1405)$ is seen in the invariant mass distribution of $\pi \Sigma$. We perform the hadronization of the quarks produced in the reaction in order to have a meson baryon pair in the final state and then let these hadron pairs undergo final state interaction from where the $\Lambda (1405)$ is dynamically generated. The reaction is particularly suited to study this resonance because we show that it filters I=0. It is also free of tree level $\pi \Sigma$ production, which leads to a clean signal of the resonance with no background. This same feature has as a consequence that one populates the state of the $\Lambda (1405)$ with higher mass around 1420 MeV, predicted by the chiral unitary approach. We make absolute predictions for the invariant mass distributions and find them within measurable range in present facilities. The implementation of this reaction would allow us to gain insight into the existence of the predicted two $\Lambda (1405)$ states and their nature as molecular states.

    hep-phPRD(2016)·21 citations
30. 30*

    Prompt charmonia production and polarization at LHC in the NRQCD with kt-factorization. Part II: ${\chi }_c$ mesons

    S.P. Baranov🇷🇺 · A.V. Lipatov🇷🇺 · N.P. Zotov🇷🇺

    In the framework of kt-factorization approach,the production of prompt ${\chi }_c$ mesons in pp collisions at the LHC energies is studied. Our consideration is based on the off-shell amplitudes for hard partonic subprocesses $g^{\ast }{g}^{\ast }\to {\chi }_{cJ}$ and non-relativistic QCD formalism for bound states. The transverse momentum dependent (unintegrated) gluon densities in a proton were derived from Ciafaloni-Catani-Fiorani-Marchesini evolution equation or, alternatively, were chosen in accordance with Kimber-Martin-Ryskin prescription. Taking into account both color singlet and color octet contributions, we deduce the corresponding non-perturbative long-distance matrix elements from the fits to the latest ATLAS data on ${\chi }_{c1}$ and ${\chi }_{c2}$ transverse momentum distributions at $\sqrt{s}=7$ TeV. We find that these distributions at small and moderate pt are formed mainly by the color singlet components. We successfully described the data on the differential cross sections and relative production rates $\sigma ({\chi }_{c2})/\sigma ({\chi }_{c1})$ presented by the ATLAS, CMS and LHCb Collaborations. We find that the fit points to unequal wave functions of ${\chi }_{c1}$ and ${\chi }_{c2}$ states.

    hep-phPRD(2016)·29 citations
31. 31*

    Supersymmetric Z' decays at the LHC

    Gennaro Corcella🇮🇹

    Searching for Z' bosons, predicted in GUT-inspired U(1)' gauge models and in the Sequential Standard Model, is one of the main challenges of the experiments carried out at the Large Hadron Collider. Such searches have so far focused on high-mass dilepton pairs, assuming that the Z' has only Standard Model decay modes, and have set mass exclusion limits around 2.5-3 TeV. In this talk, I investigate supersymmetric Z' decays at 14 TeV LHC, extending the MSSM in such a way to accommodate extra heavy gauge bosons. In particular, I study Z' decays into pairs of sleptons, charginos and neutralinos, leading to final states with leptons and missing energy, and present results for few reference points of the parameter space, consistent with a SM-like Higgs boson with a mass around 125 GeV. I also discuss the feasibility to search for Dark Matter candidates, by analysing Z' decays into the lightest MSSM neutralinos.

    hep-phPoS(2015)·1 citation
32. 32*

    Quark Nugget Dark Matter: Comparison with radio observations of nearby galaxies

    K. Lawson🇨🇦 · A.R. Zhitnitsky🇨🇦

    It has been recently claimed that radio observations of nearby spiral galaxies essentially rule out a dark matter source for the galactic haze. Here we consider the low energy thermal emission from a quark nugget dark matter model in the context of microwave emission from the galactic centre and radio observations of nearby Milky Way like galaxies. We demonstrate that observed emission levels do not strongly constrain this specific dark matter candidate across a broad range of the allowed parameter space in drastic contrast with conventional dark matter models based on the WIMP paradigm.

    ↳ astro-ph.GAastro-ph.HEhep-phPLB(2016)·6 citations
33. 33*

    Challenging the Presence of Scalar Charge and Dipolar Radiation in Binary Pulsars

    Kent Yagi🇺🇸 · Leo C. Stein🇺🇸 · Nicolas Yunes🇺🇸

    Corrections to general relativity that introduce long-ranged scalar fields which are non-minimally coupled to curvature typically predict that neutron stars possess a non-trivial scalar field profile. An observer far from a star is most sensitive to the spherically-symmetric piece of this profile that decays linearly with the inverse of the distance, the so-called scalar charge, which is related to the emission of dipolar radiation from compact binaries. The presence of dipolar radiation has the potential to very strongly constrain extended theories of gravity. These facts may lead people to believe that gravitational theories with long-ranged scalar fields have already been constrained strongly from binary pulsar observations. Here we challenge this "lore" by investigating the decoupling limit of Gauss-Bonnet gravity as an example, in which the scalar field couples linearly to the Gauss-Bonnet density in the action. We prove a theorem that neutron stars in this theory cannot possess a scalar charge. Thus Gauss-Bonnet gravity evades the strong binary pulsar constraints on dipole radiation. We discuss the astrophysical systems yielding the best constraints on Gauss-Bonnet gravity and related quadratic gravity theories. To achieve this we explicitly compute the scalar charge for slowly-rotating neutron stars in quadratic gravity theories. In generic case, either neutron star-binary or neutron star-black hole systems can be used to constrain the theory, but Gauss-Bonnet gravity evades the neutron star-binary constraints. However, black holes in Gauss-Bonnet gravity do anchor scalar charge. The best constraints on Gauss-Bonnet gravity will thus come from black hole observations, for example via pulsar-black hole binaries. We estimate these constraints to be ten times better than the current estimated bound, and also include estimated constraints on generic quadratic gravity theories.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2016)·167 citations
34. 34*

    Interaction of the vector-meson octet with the baryon octet in effective field theory

    Y. Unal🇩🇪 · A. Kucukarslan🇹🇷 · S. Scherer🇩🇪

    We analyze the constraint structure of the interaction of vector mesons with baryons using the classical Dirac constraint analysis. We show that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We then require the self-consistency condition of the interacting system in terms of perturbative renormalizability to obtain relations for the renormalized coupling constants at the one-loop level. As a result we find a universal interaction with one coupling constant which is the same as in the massive Yang-Mills Lagrangian of the vector-meson sector.

    ↳ nucl-thhep-phPRC(2015)·9 citations
35. 35*

    Search for Long-Range Correlations in Relativistic Heavy-Ion Collisions at SPS Energies

    Shakeel Ahmad🇮🇳 · Anisa Khatun🇮🇳 · Shaista Khan🇮🇳 · A. Ahmad🇮🇳 · M. Irfan🇮🇳

    Long range correlations are searched for by analyzing the experimental data on 16O-AgBr and 32S-AgBr collisions at 200A GeV/c and the results are compared with the predictions of a multi phase transport (AMPT) model. The findings reveal that the observed forward-backward (F-B) multiplicity correlations are mainly of short-range in nature. The range of F-B correlations are observed to extend with increasing projectile mass. The observed extended range of F-B correlations might be due to overall multiplicity fluctuations arising because of nuclear geometry. The findings are not sufficient for making any definite conclusions regarding the presence of long-range correlations.

    ↳ nucl-exhep-phnucl-thAdv.High Energy Phys.(2015)·4 citations
36. 36*

    Global shift symmetry and vacuum energy of matter fields

    Ja.V.Balitsky🇷🇺 · V.V.Kiselev🇷🇺

    We construct the model incorporating both an arbitrary shift of cosmological constant and Goldstone boson corresponding to the spontaneous breaking down the global shift symmetry in the matter action. The gravity breaks down the symmetry explicitly and transforms the Goldstone boson to the inflaton field.

    ↳ gr-qchep-ph0 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.