Thu·Jan 7, 2016Thursday·January 7, 2016

1. 01*

   Global analysis of nuclear parton distribution functions and their uncertainties at next-to-next-to-leading order

   Hamzeh Khanpour🇮🇷 · S. Atashbar Tehrani🇮🇷

   We perform a next-to-next-to-leading order (NNLO) analysis of nuclear parton distribution functions (nPDFs) using neutral current charged-lepton (${\ell }^{\pm }$ + nucleus) deeply inelastic scattering (DIS) data and Drell-Yan (DY) cross-section ratios ${\sigma }_{DY}^A/{\sigma }_{DY}^{A^{\prime }}$ for several nuclear targets. We study in detail the parametrizations and the atomic mass (A) dependence of the nuclear PDFs at this order. The present nuclear PDFs global analysis provides us a complete set of nuclear PDFs, $f_i^{(A,Z)}(x,Q^2)$, with a full functional dependence on $x$, A, Q${}^2$. The uncertainties of the obtained nuclear modification factors for each parton flavour are estimated using the well-known Hessian method. The nuclear charm quark distributions are also added into the analysis. We compare the parametrization results with the available data and the results of other nuclear PDFs groups. We found our nuclear PDFs to be in reasonably good agreement with them. The estimates of errors provided by our global analysis are rather smaller than those of other groups. In general, a very good agreement is achieved. We also briefly review the recent heavy-ion collisions data including the first experimental data from the LHC proton+lead and lead+lead run which can be used in the global fits of nuclear PDFs. We highlight different aspects of the high luminosity Pb--Pb and p--Pb data which have been recorded by the CMS Collaboration.

   hep-phPRD(2016)·129 citations
2. 02*

   Implications of the diphoton excess on Left-Right models and gauge unification

   Frank F. Deppisch🇬🇧 · Chandan Hati🇮🇳 · Sudhanwa Patra🇮🇳 · Prativa Pritimita🇮🇳 · Utpal Sarkar🇮🇳

   The recent diphoton excess signal at an invariant mass of 750 GeV can be interpreted in the framework of left-right symmetric models with additional scalar singlets and vector-like fermions. We propose a minimal scenario for such a purpose. Extending the LRSM framework to include these new vector-like fermionic fields, on the other hand, results in interesting phenomenological implications for the LRSM fermion masses and mixing. Furthermore, existence of such vector-like fermions can also have interesting implications for baryogenesis and the dark matter sector. The introduction of a real bi-triplet scalar which contains a potential DM candidate will allow the gauge couplings to unify at $\approx 10^{17.7}$ GeV.

   hep-phhep-exPLB(2016)·72 citations
3. 03*

   Lepton flavor (universality) violation in rare kaon decays

   Andreas Crivellin🇨🇭 · Giancarlo D'Ambrosio🇮🇹 · Martin Hoferichter🇺🇸 · Lewis C. Tunstall🇨🇭

   Recent anomalies in the decays of $B$ mesons and the Higgs boson provide hints towards lepton flavor (universality) violating physics beyond the Standard Model. We observe that four-fermion operators which can explain the $B$-physics anomalies have corresponding analogs in the kaon sector, and we analyze their impact on $K\to \pi \ell {\ell }^{\prime }$ and $K\to \ell {\ell }^{\prime }$ decays $(\ell =\mu ,e)$. For these processes, we note the corresponding physics opportunities at the NA62 experiment. In particular, assuming minimal flavor violation, we comment on the required improvements in sensitivity necessary to test the $B$-physics anomalies in the kaon sector.

   hep-phhep-exhep-latnucl-thPRD(2016)·93 citations
4. 04*

   Updated determination of the solar neutrino fluxes from solar neutrino data

   Johannes Bergstrom🇪🇸 · M.C. Gonzalez-Garcia🇪🇸 · Michele Maltoni🇪🇸 · Carlos Pena-Garay🇪🇸 · Aldo M. Serenelli🇪🇸 · Ningqiang Song🇺🇸

   We present an update of the determination of the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. We then use these results to compare the description provided by different Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with equivalent statistical agreement. We also argue that even with the present experimental precision the solar neutrino data have the potential to improve the accuracy of the solar model predictions.

   hep-phastro-ph.SRhep-exJHEP(2016)·114 citations
5. 05*

   A new and trivial CP symmetry for extended $A_4$ flavor

   C. C. Nishi🇧🇷

   The combination of ${\nu }_{\mu }$-${\nu }_{\tau }$ exchange together with CP conjugation in the neutrino sector (known as ${\mathrm{CP}}^{\mu \tau }$ symmetry or $\mu \tau$-reflection) is known to predict the viable pattern: ${\theta }_{23}=45^{\circ }$, maximal Dirac CP phase and trivial Majorana phases. We implement such a CP symmetry as a new CP symmetry in theories with $A_4$ flavor. The implementation in a complete renormalizable model leads to a new form for the neutrino mass matrix that leads to further predictions: normal hierarchical spectrum with lightest mass and $m_{\beta \beta }$ ($0\nu \beta \beta$) of only few meV, and either ${\nu }_1$ or ${\nu }_2$ has opposite CP parity. An approximate $L_{\mu }-L_{\tau }$ symmetry arises naturally and controls the flavor structure of the model. The light neutrino masses are generated by the extended seesaw mechanism with 6 right-handed neutrinos (RHNs). The requirement of negligible one-loop corrections to light neutrino masses, validity of the extended seesaw approximation and not too long-lived BSM states to comply with BBN essentially restricts the parameters of the model to a small region: three relatively light right-handed neutrinos at the GeV scale, heavier neutrinos at the electroweak scale and Yukawa couplings smaller than the electron Yukawa. Such a small Yukawa couplings render these RHNs unobservable in terrestrial experiments.

   hep-phPRD(2016)·26 citations
6. 06*

   Annihilation Rates of ${}^3{D}_2(2^{--})$ and ${}^3{D}_3(3^{--})$ Heavy Quarkonia

   Tianhong Wang🇨🇳 · Hui-Feng Fu🇨🇳 · Yue Jiang🇨🇳 · Qiang Li🇨🇳 · Guo-Li Wang🇨🇳

   We calculate the annihilation decay rates of the ${}^3{D}_2(2^{--})$ and ${}^3{D}_3(3^{--})$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. The wave functions of states with quantum numbers $J^{PC}=2^{--}$ and $3^{--}$ are constructed. By solving the corresponding instantaneous Bethe-Salpeter equations, we obtain the mass spectra and wave functions of the quarkonia. The annihilation amplitude is written within Mandelstam formalism and the relativistic corrections are taken into account properly. This is important, especially for high excited states, since their relativistic corrections are large. The results for the $3g$ channel are as follows: ${\Gamma }_{{}^3{D}_2(c\bar{c})\to ggg}=9.24$ keV, ${\Gamma }_{{}^3{D}_3(c\bar{c})\to ggg}=25.0$ keV, ${\Gamma }_{{}^3{D}_2(b\bar{b})\to ggg}=1.87$ keV, and ${\Gamma }_{{}^3{D}_3(b\bar{b})\to ggg}=0.815$ keV.

   hep-phhep-exInt.J.Mod.Phys.A(2017)·12 citations
7. 07*

   Studying 750 GeV Di-photon Resonance at Photon-Photon Collider

   Hayato Ito🇯🇵 · Takeo Moroi🇯🇵 · Yoshitaro Takaesu🇯🇵

   Motivated by the recent LHC discovery of the di-photon excess at the invariant mass of ~ 750 GeV, we study the prospect of investigating the scalar resonance at a future photon-photon collider. We show that, if the di-photon excess observed at the LHC is due to a new scalar boson coupled to the standard-model gauge bosons, such a scalar boson can be observed and studied at the photon-photon collider with the center-of-mass energy of ~ 1 TeV in large fraction of parameter space.

   hep-phhep-exPLB(2016)·50 citations
8. 08*

   Direct detection of fermion dark matter in the radiative seesaw model

   Alejandro Ibarra🇩🇪 · Carlos E. Yaguna🇩🇪 · Oscar Zapata🇨🇴

   We consider the scenario in the radiative seesaw model where the dark matter particle is the lightest $Z_2$-odd fermion. We identify the regions of the parameter space of the model compatible with neutrino oscillation data, with the upper limits from rare charged lepton decays and with the observed dark matter abundance via thermal freeze-out, and we compute the dark matter scattering cross section with nuclei via the one-loop exchange of a photon, a $Z^0$-boson or a Higgs boson. We find that the predicted spin-independent cross section lies below the current LUX limit, although, for some choices of parameters, above the expected sensitivity of XENON1T or LZ.

   hep-phPRD(2016)·80 citations
9. 09*

   New Developments in FeynCalc 9.0

   Vladyslav Shtabovenko🇩🇪 · Rolf Mertig🇩🇪 · Frederik Orellana🇩🇰

   In this note we report on the new version of FeynCalc, a Mathematica package for symbolic semi-automatic evaluation of Feynman diagrams and algebraic expressions in quantum field theory. The main features of version 9.0 are: improved tensor reduction and partial fractioning of loop integrals, new functions for using FeynCalc together with tools for reduction of scalar loop integrals using integration-by-parts (IBP) identities, better interface to FeynArts and support for SU(N) generators with explicit fundamental indices.

   hep-phComput.Phys.Commun.(2016)·1142 citations
10. 10*

    Initial state and pre-equilibrium effects in small systems

    S. Schlichting🇺🇸

    We discuss the importance of initial state and early time effects with regard to the theoretical understanding of long range azimuthal correlations observed in high-multiplicity $p+p$ and $p+A$ collisions.

    hep-phnucl-thNPA(2016)·12 citations
11. 11*

    A Comparative Study of Nucleon Structure in Light-Front Quark Models in AdS/QCD

    Chandan Mondal🇮🇳 · Dipankar Chakrabarti🇮🇳

    We present a comparative study of nucleon structure such as electromagnetic form factors, transverse charge and magnetization densities in three different models within AdS/QCD framework.

    hep-phFew Body Syst.(2016)·7 citations
12. 12*

    Elastic and Transition Form Factors in DSEs

    Jorge Segovia🇪🇸

    A symmetry preserving framework for the study of continuum Quantum Chromodynamics (QCD) is obtained from a truncated solution of the QCD equations of motion or QCD's Dyson-Schwinger equations (DSEs). A nonperturbative solution of the DSEs enables the study of, e.g., hadrons as composites of dressed-quarks and dressed-gluons, the phenomena of confinement and dynamical chiral symmetry breaking (DCSB), and therefrom an articulation of any connection between them. It is within this context that we present a unified study of Nucleon, Delta and Roper elastic and transition form factors, and compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-like momentum dependence with results obtained using a symmetry-preserving treatment of a vector$\otimes$vector contact-interaction.

    ↳ nucl-thhep-exhep-lathep-phFew Body Syst.(2016)·3 citations
13. 13*

    History of Belle and some of its lesser known highlights

    Stephen Lars Olsen🇰🇷

    I report on the early history of Belle, which was almost entirely focused on testing the Kobayashi Maskawa mechanism for $CP$ violation that predicted large matter-antimatter asymmetries in certain $B$ meson decay modes. Results reported by both BaBar and Belle in the summer of 2001 verified the Kobayashi Maskawa idea and led to their Nobel prizes in 2008. In addition to studies of CP violation, Belle (and BaBar) reported a large number of important results on a wide variety of other subjects, many of which that had nothing to do with B mesons. In this talk I cover three (of many) subjects where Belle measurements have had a significant impact on specific sub-fields of hadron physics but are not generally well know. These include: the discovery of an anomalously large cross sections for double charmonium production in continuum e+e- annihilation; sensitive probes of the structure of the low-mass scalar mesons; and first measurements of the Collins spin fragmentation function.

    ↳ hep-exhep-ph2 citations
14. 14*

    The mass of heavy-light mesons in a constituent quark picture with partially restored chiral symmetry

    Aaron Park🇰🇷 · Philipp Gubler🇮🇹 · Masayasu Harada🇯🇵 · Su Houng Lee🇰🇷 · Chiho Nonaka🇯🇵 · Woosung Park🇰🇷

    We probe effects of the partial chiral symmetry restoration to the mass of heavy-light mesons in a constituent quark model by changing the constituent quark mass of the light quark. Due to the competing effect between the quark mass and the linearly rising potential, whose contribution to the energy increases as the quark mass decreases, the heavy-light meson mass has a minimum value near the constituent quark mass typically used in the vacuum. Hence, the meson mass increases as one decreases the constituent quark mass consistent with recent QCD sum rule analyses, which show an increasing $D$ meson mass as the chiral order parameter decreases.

    ↳ nucl-thhep-phPRD(2016)·24 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.