Wed·Oct 7, 2015Wednesday·October 7, 2015

1. 01*

   Probing Leptonic Models at the LHC

   Frank F. Deppisch🇬🇧

   Models of neutrino mass generation provide well motivated scenarios of Beyond-the-Standard-Model physics. The synergy between low energy and high energy LHC searches facilitates an effective approach to rule out, constrain or ideally pinpoint such models. In this proceedings report, we provide a brief overview of scenarios where searches at the LHC can help determine the mechanism of light neutrino masses and potentially falsify baryogenesis mechanisms.

   hep-ph1 citation
2. 02*

   Status of Chiral-Scale Perturbation Theory

   R.J. Crewther🇦🇺 · Lewis C. Tunstall🇨🇭

   Chiral-scale perturbation theory $\chi$PT${}_{\sigma }$ has been proposed as an alternative to chiral $SU(3{)}_L\times SU(3{)}_R$ perturbation theory which explains the $\Delta I=1/2$ rule for kaon decays. It is based on a low-energy expansion about an infrared fixed point in three-flavor QCD. In $\chi$PT${}_{\sigma }$, quark condensation $⟨\bar{q}q{⟩}_{\mathrm{vac}}\ne 0$ induces nine Nambu-Goldstone bosons: $\pi ,K,\eta$ and a QCD dilaton $\sigma$ which we identify with the $f_0(500)$ resonance. Partial conservation of the dilatation and chiral currents constrains low-energy constants which enter the effective Lagrangian of $\chi$PT${}_{\sigma }$. These constraints allow us to obtain new phenomenological bounds on the dilaton decay constant via the coupling of $\sigma /f_0$ to pions, whose value is known precisely from dispersive analyses of $\pi \pi$ scattering. Improved predictions for $\sigma \to \gamma \gamma$ and the $\sigma NN$ coupling are also noted. To test $\chi$PT${}_{\sigma }$ for kaon decays, we revive a 1985 proposal for lattice methods to be applied to $K\to \pi$ on-shell.

   hep-phhep-latnucl-thPoS(2015)·24 citations
3. 03*

   Supersoft Supersymmetry, Conformal Sequestering, and Single Scale Supersymmetry Breaking

   Ran Ding🇨🇳 · Tianjun Li🇨🇳 · Florian Staub🇨🇭 · Bin Zhu🇨🇳

   Supersymmetric Standard Models (SSMs) with Dirac gauginos have the appealing supersoft property that they only cause finite contributions to scalar masses. Considering gauge mediated SUSY breaking with conformal sequestering and assuming there is one and only one fundamental parameter with dimension mass arising from supersymmetry breaking, we find a cancellation between the dominant terms that contribute to the EWFT. The resulting EWFT measure can be of order one even for supersymmetric particle masses and $\mu$-terms in the TeV range.

   hep-phPRD(2016)·15 citations
4. 04*

   Diquark Substructure in $\varphi$ Photoproduction

   Richard F. Lebed🇺🇸

   Observed enhancements in the forward and backward directions for $\varphi$ meson photoproduction off nucleons are shown to be explainable by the production of a nonresonant recoiling $(su)$ diquark, $(\bar{s}ud)$ triquark pair. We show that the necessity of maintaining approximate collinearity of the quarks within these units constrains configurations with the minimum momentum transfer, and hence maximal amplitudes, to lie preferentially along the reaction axis.

   hep-phPRD(2015)·14 citations
5. 05*

   Stop Decay with LSP Gravitino in the final state: ${\tilde{t}}_1\to \tilde{G}Wb$

   J. Lorenzo Díaz Cruz🇲🇽 · Bryan O. Larios🇲🇽

   In MSSM scenarios where the gravitino is the lightest supersymmetric particle (LSP), and therefore a viable dark matter candidate, the stop ${\tilde{t}}_1$ could be the next-to-lightest superpartner (NLSP). For a mass spectrum satisfying: $m_{\tilde{G}}+m_t>m_{{\tilde{t}}_1}>m_{\tilde{G}}+m_b+m_W$, the stop decay is dominated by the 3-body mode ${\tilde{t}}_1\to bW\tilde{G}$. We calculate the stop life-time, including the full contributions from top, sbottom and chargino as intermediate states. We also evaluate the stop lifetime for the case when the gravitino can be approximated by the goldstino state. Our analytical results are conveniently expressed using an expansion in terms of the intermediate state mass, which helps to identify the massless limit. In the region of low gravitino mass ($m_{\tilde{G}}\ll m_{{\tilde{t}}_1}$) the results obtained using the gravitino and goldstino cases turns out to be similar, as expected. However for higher gravitino masses $m_{\tilde{G}}\lesssim m_{{\tilde{t}}_1}$ the results for the lifetime could show a difference of O(100)\%.

   hep-phEPJC(2016)·4 citations
6. 06*

   Earth matter effect on atmospheric neutrino oscillation in (3+3) model

   Mushfiqur Rahman🇺🇸

   In a recent combined analysis of short baseline neutrino oscillation data by Conrad et al it is shown that (3+3) neutrino model, defined by three active and three sterile neutrinos, results in an overall goodness of $67\%$ and a compatibility of $90\%$ among all data sets - to be compared to the compatibility of $0.043\%$ and $13\%$ for a (3+1) and a (3+2) model, respectively. Aside from the fact that (3+3) model still finds inconsistencies with MiniBooNE appearance data sets, its high quality overall compatibility and goodness of fit led us to study the atmospheric neutrinos in this model which travel distances of thousands of kilometers through earth. We show that in this mixing scheme matter resonance effect inside earth enhances the small vacuum oscillations into near-maximal transitions and at high energies these maximal transitions occur in the TeV range, whereas at low energies those can occur in the few GeV region. We also calculate the zenith angle distributions of ${\nu }_{\mu }^{CC}$(charged current) events in the 10 - 100 GeV energy range in DeepCore sub-array of the IceCube Neutrino Observatory and comment on the possibility of probing active neutrino mass hierarchy and six neutrino scenario.

   hep-phastro-ph.HE4 citations
7. 07*

   On the role of dynamical quark mass generation in chiral symmetry breaking in QCD

   H. Sazdjian🇫🇷

   The phenomenon of dynamical quark mass generation is studied in QCD within the framework of a gauge invariant formalism. An exact relationship is established between the equation satisfied by the scalar part of the two-point gauge invariant quark Green's function and the quark-antiquark bound state equation in the chiral limit. A possible nontrivial solution of the former yields a massless pseudoscalar solution of the bound state equation with vanishing total momentum. The result is also corroborated by the corresponding Ward-Takahashi identity. The problem is explicitly solved in two-dimensional QCD in the large-$N_c$ limit.

   hep-phNucl.Part.Phys.Proc.(2016)·0 citations
8. 08*

   Diffractive $\rho$ production at small $x$ in future Electron - Ion Colliders

   V. P. Goncalves🇧🇷 · F. S. Navarra🇧🇷 · D. Spiering🇧🇷

   The future Electron - Ion ($eA$) Collider is expected to probe the high energy regime of the QCD dynamics, with the exclusive vector meson production cross section being one of the most promising observables. In this paper we complement previous studies of exclusive processes presenting a comprehensive analysis of diffractive $\rho$ production at small $x$. We compute the coherent and incoherent cross sections taking into account non-linear QCD dynamical effects and considering different models for the dipole - proton scattering amplitude and for the vector meson wave function. The dependence of these cross sections with the energy, photon virtuality, nuclear mass number and squared momentum transfer is analysed in detail. Moreover, we compare the non-linear predictions with those obtained in the linear regime. Finally, we also estimate the exclusive photon, $J/\Psi$ and $\varphi$ production and compare with the results obtained for $\rho$ production. Our results demonstrate that the analysis of diffractive $\rho$ production in future electron - ion colliders will be important to understand the non-linear QCD dynamics.

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

   Merging weak and QCD showers with matrix elements

   Jesper Roy Christiansen🇸🇪 · Stefan Prestel🇺🇸

   We present a consistent way of combining associated weak boson radiation in hard dijet events with hard QCD radiation in Drell-Yan-like scatterings. This integrates multiple tree-level calculations with vastly different cross sections, QCD- and electroweak parton shower resummation into a single framework. The new merging strategy is implemented in the PYTHIA event generator and predictions are confronted with LHC data. Improvements over the previous strategy are observed. Results of the new electroweak-improved merging at a future 100 TeV proton collider are also investigated.

   hep-phEPJC(2016)·27 citations
10. 10*

    Perturbativity Limits for Scalar Minimal Dark Matter with Yukawa Interactions: Septuplet

    Chengfeng Cai🇨🇳 · Ze-Min Huang🇨🇳 · Zhaofeng Kang🇰🇷 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

    The candidate of minimal dark matter (MDM) is limited if one demands perturbativity up to a very high scale, and it was believed that the MDM model with a real scalar septuplet could keep perturbative up to the Planck or GUT scale. In this work we point out that it is not true after taking into account the running of the quartic self-couplings of the scalar septuplet. For the septuplet mass around $10$ TeV, which is suggested by the observed dark matter relic abundance, these couplings would hit the Landau pole at a scale $\sim 10^8-10^9$ GeV, much lower than the Planck scale. We attempt to push up the Landau pole scale as high as possible by proposing an extension with extra Yukawa interactions of the septuplet. We find that in principle the Landau pole could be deferred to a scale of $\sim 10^{14}$ GeV if one could tolerate a serious fine-tuning of the initial condition of the Yukawa coupling. Moreover, if the MDM particle mass could be relaxed to $\sim 10^8$ GeV, which would need some nonthermal production mechanisms to give a correct relic abundance, the Landau pole scale could be pushed up above the Planck scale.

    hep-phPRD(2015)·32 citations
11. 11*

    Neutral pion photoproduction on protons in fully covariant ChPT with Delta(1232) loop contributions

    Astrid Hiller Blin🇪🇸 · Tim Ledwig🇪🇸 · Manuel Vicente Vacas🇪🇸

    We study the neutral pion photoproduction at near-threshold energies in fully covariant chiral perturbation theory up to O(p^3). When including only nucleonic virtual states in the model, the convergence is too slow. Therefore we test the model when introducing the Delta(1232) resonance as an additional degree of freedom. Some low-energy constants were fitted, converging to values in good agreement with those expected from literature.

    hep-phPoS(2016)·2 citations
12. 12*

    Examination of pairs in neutrino mixing matrix

    Dianjing Liu🇨🇳 · Bo-Qiang Ma🇨🇳

    We exam the pairs of neutrino mixing matrix and suggest pairs that can be used in the construction of new mixing patterns, with "pair" denoting the equality of the modulus of a pair of matrix elements. The results show that the tri-maximal mixing in ${\nu }_2$ and the $\mu$-$\tau$ interchange symmetry are good choices under current experimental results. The two cases of bi-pair mixing pattern depend on the mass hierarchy of neutrinos. We also derive constraints on the CP-phase by the pairs. The results are compatible with the maximal CP-violation in most cases that are both self-consistent and consistent with experimental results.

    hep-phPRD(2015)·1 citation
13. 13*

    Mueller-Navelet jets at LHC: discriminating BFKL from DGLAP by asymmetric cuts

    Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Beatrice Murdaca🇮🇹 · Alessandro Papa🇮🇹

    The Mueller-Navelet di-jet production process represents an ultimate testfield of pQCD in the high-energy limit. Several experimental analyses carried out so far are in good agreement with theoretical predictions, based on collinear factorization and BFKL resummation of energy logarithms in the next-to-leading approximation, with the CMS experimental data at center-of-mass energy equal to 7 TeV. However, the question if the same data can be described also by fixed-order perturbative approaches has not yet been fully answered. We discuss how the use of partially asymmetric cuts in the transverse momenta of the detected jets allows to discriminate between BFKL-resummed and fixed-order predictions (the latter in the high-energy limit) in observables related with this process at LHC.

    hep-phActa Phys.Polon.Supp.(2015)·69 citations
14. 14*

    Kaon regeneration in perturbation theory

    Valeriy Nazaruk🇷🇺

    $K^0{\bar{K}}^0$ transitions in a medium followed by decay and regeneration of $K_S^0$-component are considered by means of perturbation theory. It is shown that in the previous calculations the problem different from regeneration is solved.

    hep-ph2 citations
15. 15*

    Particle production in the background with VEV depending on time

    Olga Czerwinska🇵🇱 · Seishi Enomoto🇵🇱 · Zygmunt Lalak🇵🇱

    It is known that time-dependent vacuum expectation value of the background field may lead to abundant particle production in the early Universe. In supersymmetric theories bosons and fermions are produced in a correlated manner that depends on the details of the supersymmetric scenario. Paper presents the general method of calculating the number density of produced particles based on the WKB approximation and the generalized Bogoliubov transformation law. The impact of the backreaction and rescattering is emphasized, also in models with more than one coupling constant.

    hep-phPoS(2015)·0 citations
16. 16*

    Status of chiral perturbation theory for light mesons

    Gerhard Ecker🇦🇹

    The status of chiral perturbation theory in the meson sector is illustrated with several topical examples. The longtime discrepancy between theory and experiment for the charged pion polarizabilities has now been resolved in favour of the chiral SU(2) result to next-to-next-to-leading order. For chiral SU(3), the main obstacles are the large number of badly known coupling constants (LECs) and the lack of convergence of the low-energy expansion in many cases of interest. I describe a new global fit of the LECs in the strong sector that leads to a prediction of the CKM matrix element $V_{us}$ in agreement with the latest lattice determinations. The slow convergence of the chiral series is particularly acute in transitions with strong final-state interactions calling for dispersive treatments. The status of dispersive approaches is reviewed for $K_{\ell 4}$ decays and for $\eta ->3\pi$ decays where precise measurements of Dalitz plot distributions have recently become available.

    hep-phhep-exPoS(2015)·13 citations
17. 17*

    Initial conditions from the shadowed Glauber model

    Sandeep Chatterjee🇮🇳 · Sushant K. Singh🇮🇳 · Snigdha Ghosh🇮🇳 · Md Hasanujjaman🇮🇳 · Jane Alam🇮🇳 · Sourav Sarkar🇮🇳

    The two component Monte-Carlo Glauber model predicts a knee-like structure in the centrality dependence of elliptic flow $v_2$ in Uranium+Uranium collisions at $\sqrt{s_{NN}}=193$ GeV. It also produces a strong anti-correlation between $v_2$ and $d{N}_{ch}/dy$ in the case of top ZDC events. However, none of these features have been observed in data. We address these discrepancies by including the effect of nucleon shadowing to the two component Monte-Carlo Glauber model. Apart from addressing successfully the above issues, we find that the nucleon shadow suppresses the event by event fluctuation of various quantities, e.g. ${\epsilon }_2$ which is in accordance with expectation from the dynamical models of initial condition based on gluon saturation physics.

    ↳ nucl-thhep-phnucl-exPLB(2016)·26 citations
18. 18*

    The Wigner-Eckart Theorem for Reducible Symmetric Cartesian Tensor Operators

    Antonio O. Bouzas🇲🇽

    We explicitly establish a unitary correspondence between spherical irreducible tensor operators and cartesian tensor operators of any rank. That unitary relation is implemented by means of a basis of integer-spin wave functions that constitute simultaneously a basis of the spaces of cartesian and spherical irreducible tensors. As a consequence, we extend the Wigner--Eckart theorem to cartesian irreducible tensor operators of any rank, and to totally symmetric reducible ones. We also discuss the tensorial structure of several standard spherical irreducible tensors such as ordinary, bipolar and tensor spherical harmonics, spin-polarization operators and multipole operators. As an application, we obtain an explicit expression for the derivatives of any order of spherical harmonics in terms of tensor spherical harmonics.

    ↳ quant-phhep-phnucl-thRept.Math.Phys.(2016)·1 citation
19. 19*

    Proton and kaon timelike form factors from BABAR

    S. I. Serednyakov🇷🇺

    The latest BABAR results on the proton and kaon timelike form factors (FF) are presented. The special emphasize is made on comparison of the spacelike and timelike FFs and the rise of the proton FF near threshold. The behavior of the cross section of e+e- annihilation into hadrons near the nucleon-antinucleon threshold is discussed.

    ↳ hep-exhep-ph0 citations
20. 20*

    Thermalization of dense hadronic matter in Au + Au collisions at the energies available at FAIR

    Somnath De🇮🇳 · Sudipan De🇧🇷 · Subhasis Chattopadhyay🇮🇳

    The conditions of local thermodynamic equilibrium of baryons (non-strange, strange) and mesons (strange) are presented for central Au + Au collisions at FAIR energies using the microscopic transport model UrQMD. The net particle density, longitudinal-to-transverse pressure anisotropy and inverse slope parameters of the energy spectra of non-strange and strange hadrons are calculated inside a cell in the central region within rapidity window $|y|<1.0$ at different time steps after the collision. We observed that the strangeness content is dominated by baryons at all energies, however contribution from mesons become significant at higher energies. The time scale obtained from local pressure (momentum) isotropization and thermalization of energy spectra are nearly equal and found to decrease with increase in laboratory energy. The equilibrium thermodynamic properties of the system are obtained with statistical thermal model. The time evolution of the entropy densities at FAIR energies are found very similar with the ideal hydrodynamic behaviour at top RHIC energy.

    ↳ nucl-thhep-phPRC(2016)·8 citations
21. 21*

    LHC results for dark matter from ATLAS and CMS

    Annapaola de Cosa (on behalf of the CMS and ATLAS collaborations)🇨🇭

    The CMS and ATLAS collaborations searched for Dark Matter (DM) particles directly produced in pair. The searches are performed using the full LHC Run-I dataset recorded with the CMS and ATLAS detectors in proton-proton collisions at a center-of-mass energy of 8 TeV. Signatures considered include those yielding energetic jets and large missing transverse momentum as well as electroweak bosons and heavy flavour quarks plus missing transverse energy. No deviation from SM background expectation was found and exclusion limits on DM production cross section were set.

    ↳ hep-exhep-ph12 citations
22. 22*

    Potential of Geo-neutrino Measurements at JUNO

    Ran Han🇨🇳 · Yu-Feng Li🇨🇳 · Liang Zhan🇨🇳 · William F. McDonough🇺🇸 · Jun Cao🇨🇳 · Livia Ludhova🇮🇹

    The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt KamLAND and 0.3-kt Borexino detectors with these measurements being limited by their low statistics. The planned 20-kt JUNO detector will provide an exciting opportunity to obtain a high statistics measurement, which will provide data to address several questions of geological importance. This paper presents the JUNO detector design concept, the expected geo-neutrino signal and corresponding backgrounds. The precision level of geo-neutrino measurements at JUNO is obtained with the standard least-squares method. The potential of the Th/U ratio and mantle measurements is also discussed.

    ↳ physics.ins-dethep-exhep-phphysics.geo-phCPC(2016)·34 citations
23. 23*

    A new high sensitivity search for neutron-antineutron oscillations at the ESS

    David Milstead🇸🇪

    A sensitive search for neutron-antineutron oscillations can provide a unique probe of some of the central questions in particle physics and cosmology: the energy scale and mechanism for baryon number violation, the origin of the baryon-antibaryon asymmetry of the universe, and the mechanism for neutrino mass generation. A remarkable opportunity has emerged to search for such oscillations with the construction of the European Spallation Source (ESS). A collaboration has been formed which has proposed a search at the ESS, which would provide a sensitivity to the oscillation probability which is three orders of magnitude greater than that achieved at an ILL experiment at which the present best limit on free neutron-antineutron oscillations was obtained.

    ↳ physics.ins-dethep-exhep-phPoS(2015)·17 citations
24. 24*

    Asymptotic freedom of gluons in the Fock space

    Stanisław D. Głazek🇵🇱 · Maria Gómez-Rocha🇮🇹

    Asymptotic freedom of gluons is described in terms of a family of scale-dependent renormalized Hamiltonian operators acting in the Fock space. The Hamiltonians are obtained by applying the renormalization group procedure for effective particles to quantum Yang-Mills theory.

    ↳ hep-thhep-phActa Phys.Polon.B(2016)·1 citation

* 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.