Thu·May 19, 2016Thursday·May 19, 2016

1. 01*

   Thermal Spectrum of Heavy Vector and Axial Vector Mesons in the Framework of QCD Sum Rules Method

   Enis Yazici🇹🇷

   The masses and the leptonic decay constants of vector and axial vector heavy-heavy mesons are calculated using the thermal QCD sum rules approach. While obtaining the QCD sum rules, additional operators in the Wilson expansion and also temperature dependency of the continuum threshold are taken into account. The masses and the decay constants remained unchanged up to $T\simeq 100MeV$. After that point, they start to diminish. At the critical temperature, the masses decreased about $3\%$, $5\%$ and $14\%$ for the vector mesons ${\rm Y}$, $B_c$ and $J/\psi$; $6\%$, $7\%$ and $22\%$ for the axial vector mesons ${\chi }_{b1}$, $B_c$ and ${\chi }_{c1}$, respectively. The decay constants reached about less than $20\%$ of their vacuum values. The obtained results of the thermal mass and decay constant calculations at zero temperature are in a very good agreement with the other non-perturbative calculations at vacuum as well as with the experimental data.

   hep-ph3 citations
2. 02*

   Shear Viscosity of Turbulent Chiral Plasma

   Avdhesh Kumar🇮🇳 · Jitesh R. Bhatt🇮🇳 · Amita Das🇮🇳 · P. K. Kaw🇮🇳

   It is well known that the difference between the chemical potentials of left-handed and right-handed particles in a parity violating (chiral) plasma can lead to an instability. We show that the chiral instability may drive turbulent transport. Further we estimate the anomalous viscosity of chiral plasma arising from the enhanced collisionality due to turbulence.

   hep-phnucl-th1 citation
3. 03*

   The Di-Photon Excess in a Perturbative SUSY Model

   Karim Benakli🇫🇷 · Luc Darmé🇫🇷 · Mark D. Goodsell🇫🇷 · Julia Harz🇫🇷

   We show that a 750 GeV di-photon excess as reported by the ATLAS and CMS experiments can be reproduced by the Minimal Dirac Gaugino Supersymmetric Standard Model (MDGSSM) without the need of any ad-hoc addition of new states. The scalar resonance is identified with the spin-0 partner of the Dirac bino. We perform a thorough analysis of constraints coming from the mixing of the scalar with the Higgs boson, the stability of the vacuum and the requirement of perturbativity of the couplings up to very high energy scales. We exhibit examples of regions of the parameter space that respect all the constraints while reproducing the excess. We point out how trilinear couplings that are expected to arise in supersymmetry-breaking mediation scenarios, but were ignored in the previous literature on the subject, play an important role.

   hep-phNPB(2016)·32 citations
4. 04*

   Soft Gamma Rays from Heavy WIMPs

   Manuel Ernst Krauss🇩🇪 · Toby Opferkuch🇩🇪 · Florian Staub🇨🇭 · Martin Wolfgang Winkler🇩🇪

   We propose an explanation of the galactic center gamma ray excess by supersymmetric WIMPs as heavy as 500 GeV. The lightest neutralino annihilates into vector-like leptons or quarks which cascade decay through intermediate Higgs bosons. Due to the long decay chains, the gamma ray spectrum is much softer than naively expected and peaks at GeV energies. The model predicts correlated diboson and dijet signatures to be tested at the LHC.

   hep-phastro-ph.HEPhys.Dark Univ.(2016)·8 citations
5. 05*

   Lepton number symmetry as a way to testable leptogenesis

   Michele Lucente🇧🇪 · Asmaa Abada🇫🇷 · Giorgio Arcadi🇫🇷 · Valerie Domcke🇫🇷

   We propose a minimal and motivated extension of the Standard Model characterised by an approximate lepton number conservation, which is able to simultaneously generate neutrino masses and to account for a successful baryogenesis via leptogenesis. The sterile fermions involved in the leptogenesis process have masses at the GeV scale. We determine the viable parameter space that complies with both the neutrino and baryogenesis phenomenology, and analyse the different regimes for the generation of a lepton asymmetry in the early Universe (weak and strong-washout) in order to determine their testability in future experimental facilities.

   hep-phhep-ex2 citations
6. 06*

   LHC Future Prospects of the 750 GeV Resonance

   Ryosuke Sato🇮🇱 · Kohsaku Tobioka🇮🇱

   A quantitative discussion on the future prospects of the 750 GeV resonance at the LHC experiment is given using a simple effective field theory analysis. The relative size of two effective operators relevant to diphoton decays can be probed by ratios of diboson signals in a robust way. We obtain the future sensitivities of $Z\gamma$, $ZZ$ and $WW$ resonance searches at the high luminosity LHC, rescaling from the current sensitivities at $\sqrt{s}=13$ TeV. Then, we show that a large fraction of parameter space in the effective field theory will be covered with 300 fb${}^{-1}$ and almost the whole parameter space will be tested with 3000 fb${}^{-1}$. This discussion is independent of production processes, other decay modes and total decay width.

   hep-phhep-exPLB(2016)·11 citations
7. 07*

   Light WIMP searches involving electron scattering

   J.D. Vergados (University of Ioannina, Ioannina, Greece)🇦🇺 · Ch. C. Moustakidis (Aristotelian University of Thessaloniki, Thessaloniki, Greece)🇬🇷 · Yeuk-Kwan E. Cheung (Nanjing University, Nanjing, China)🇨🇳 · H. Ejri (RCNP, Osaka University, Osaka, Japan)🇯🇵 · Y. Kim (Center for Underground Physics IBS, Daejeon, Republic of Korea)🇰🇷 · Yeong Lie (Center for Underground Physics IBS, Daejeon, Republic of Korea)🇰🇷

   In the present work we examine the possibility for detecting electrons in dark matter searches. These detectors are considered to be the most appropriate for detecting light dark matter particles in the MeV region. We analyze theoretically some key issues involved in such a detection and we perform calculations for the expected rates employing reasonable theoretical models.

   hep-phAdv.High Energy Phys.(2018)·12 citations
8. 08*

   Scaling violation and the magnetic equation of state in chiral models

   Gabor Andras Almasi🇩🇪 · Wojciech Tarnowski🇵🇱 · Bengt Friman🇩🇪 · Krzysztof Redlich🇵🇱

   The scaling behavior of the order parameter at the chiral phase transition, the so-called magnetic equation of state, of strongly interacting matter is studied within effective models. We explore universal and nonuniversal structures near the critical point. These include the scaling functions, the leading corrections to scaling, and the corresponding size of the scaling window as well as their dependence on an external symmetry breaking field. We consider two models in the mean-field approximation, the quark-meson and the Polyakov loop extended quark-meson (PQM) models, and compare their critical properties with a purely bosonic theory, the $O(N)$ linear sigma model in the $N\to \infty$ limit. In these models the order parameter scaling function is found analytically using the high temperature expansion of the thermodynamic potential. The effects of a gluonic background on the nonuniversal scaling parameters are studied within the PQM model.

   hep-phPRD(2017)·6 citations
9. 09*

   Separating Electroweak and Strong interactions in Drell-Yan processes at LHC: leptons angular distributions and reference frames

   E. Richter-Was🇵🇱 · Z. Was🇵🇱

   Among the physics goals of LHC experiments, precision tests of the Standard Model in the Strong and Electroweak sectors play an important role. Because of nature of the proton-proton processes, observables based on the measurement of the direction and energy of leptons provide the most precise signatures. In the present paper, we concentrate on the angular distribution of Drell-Yan process leptons, in the lepton-pair rest-frame. The vector nature of the intermediate state imposes that distributions are to a good precision described by spherical polynomials of at most second order. We show that with the proper choice of the coordinate frames, only one coefficient in this polynomial decomposition remains sizable, even in the presence of one or two high $p_T$ jets. The necessary stochastic choice of the frames relies on probabilities independent from any coupling constants. This remains true when one or two partons accompany the lepton pairs. In this way electroweak effects can be better separated from strong interaction ones for the benefit of the interpretation of the measurements. Our study exploits properties of single gluon emission matrix elements which are clearly visible if a conveniently chosen form of their representation is used. We rely also on distributions obtained from matrix element based Monte Carlo generated samples of events with two leptons and up to two additional partons in test samples. Incoming colliding protons' partons are distributed accordingly to PDFs and are strictly collinear to the corresponding beams.

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

    Light sterile neutrino sensitivity of 163Ho experiments

    L. Gastaldo🇩🇪 · C. Giunti🇮🇹 · E. M. Zavanin🇧🇷

    We explore the sensitivity of ${}^{163}$Ho electron capture experiments to neutrino masses in the standard framework of three-neutrino mixing and in the framework of 3+1 neutrino mixing with a sterile neutrino which mixes with the three standard active neutrinos, as indicated by the anomalies found in short-baseline neutrino oscillations experiments. We calculate the sensitivity to neutrino masses and mixing for different values of the energy resolution of the detectors, of the unresolved pileup fraction and of the total statistics of events, considering the expected values of these parameters in the two planned stages of the ECHo project (ECHo-1k and ECHo-1M). We show that an extension of the ECHo-1M experiment with the possibility to collect $10^{16}$ events will be competitive with the KATRIN experiment. This statistics will allow to explore part of the 3+1 mixing parameter space indicated by the global analysis of short-baseline neutrino oscillation experiments. In order to cover all the allowed region, a statistics of about $10^{17}$ events will be needed.

    hep-phhep-exJHEP(2016)·12 citations
11. 11*

    Scalar and vector self-energies of heavy baryons in nuclear medium

    K. Azizi🇹🇷 · N. Er🇹🇷 · H. Sundu🇹🇷

    The in-medium sum rules are employed to calculate the shifts in the mass and residue as well as the scalar and vector self-energies of the heavy ${\Lambda }_Q,{\Sigma }_Q$ and ${\Xi }_Q$ baryons, with Q being $b$ or $c$ quark. The maximum shift in mass due to nuclear matter belongs to the ${\Sigma }_c$ baryon and it is found to be $\Delta m_{{\Sigma }_c}=-936MeV$. In the case of residue, it is obtained that the residue of ${\Sigma }_b$ baryon is maximally affected by the nuclear medium with the shift $\Delta {\lambda }_{{\Sigma }_b}=-0.014Ge{V}^3$. The scalar and vector self-energies are found to be ${\Sigma }_{{\Lambda }_b}^S=653MeV$, ${\Sigma }_{{\Sigma }_b}^S=-614MeV$, ${\Sigma }_{{\Xi }_b}^S=-17MeV$, ${\Sigma }_{{\Lambda }_c}^S=272MeV$, ${\Sigma }_{{\Sigma }_c}^S=-936MeV$, ${\Sigma }_{{\Xi }_c}^S=-5MeV$ and ${\Sigma }_{{\Lambda }_b}^{\nu }=436\pm 148MeV$, ${\Sigma }_{{\Sigma }_b}^{\nu }=382\pm 129MeV$, ${\Sigma }_{{\Xi }_b}^{\nu }=15\pm 5MeV$, ${\Sigma }_{{\Lambda }_c}^{\nu }=151\pm 45MeV$, ${\Sigma }_{{\Sigma }_c}^{\nu }=486\pm 144MeV$ and ${\Sigma }_{{\Xi }_c}^{\nu }=1.391\pm 0.529MeV$.

    hep-phnucl-thNPA(2017)·20 citations
12. 12*

    The Complete $O({\alpha }_s^2)$ Non-Singlet Heavy Flavor Corrections to the Structure Functions $g_{1,2}^{ep}(x,Q^2)$, $F_{1,2,L}^{ep}(x,Q^2)$, $F_{1,2,3}^{\nu (\bar{\nu })}(x,Q^2)$ and the Associated Sum Rules

    Johannes Blümlein🇩🇪 · Giulio Falcioni🇩🇪 · Abilio De Freitas🇩🇪

    We calculate analytically the flavor non-singlet $O({\alpha }_s^2)$ massive Wilson coefficients for the inclusive neutral current non-singlet structure functions $F_{1,2,L}^{ep}(x,Q^2)$ and $g_{1,2}^{ep}(x,Q^2)$ and charged current non-singlet structure functions $F_{1,2,3}^{\nu (\bar{\nu })p}(x,Q^2)$, at general virtualities $Q^2$ in the deep-inelastic region. Numerical results are presented. We illustrate the transition from low to large virtualities for these observables, which may be contrasted to basic assumptions made in the so-called variable flavor number scheme. We also derive the corresponding results for the Adler sum rule, the unpolarized and polarized Bjorken sum rules and the Gross-Llewellyn Smith sum rule. There are no logarithmic corrections at large scales $Q^2$ and the effects of the power corrections due to the heavy quark mass are of the size of the known $O({\alpha }_s^4)$ corrections in the case of the sum rules. The complete charm and bottom corrections are compared to the approach using asymptotic representations in the region $Q^2\gg m_{c,b}^2$. We also study the target mass corrections to the above sum rules.

    hep-phhep-exNPB(2016)·78 citations
13. 13*

    Spectra of heavy-light mesons in a relativistic model

    Jing-Bin Liu🇨🇳 · Cai-Dian Lu🇨🇳

    The spectra and wave functions of heavy-light mesons are calculated within a relativistic quark model, which is based on a heavy-quark expansion of the instantaneous Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation. The kernel we choose is the standard combination of linear scalar and Coulombic vector. The effective Hamiltonian for heavy-light quark-antiquark system is calculated up to order $1/m_Q^2$. Our results are in good agreement with available experimental data except for the anomalous $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ states. The newly observed heavy-light meson states can be accommodated successfully in the relativistic quark model with their assignments presented. The $D_{sJ}^{\ast }(2860)$ can be interpreted as the $|1^{3/2}{D}_1⟩$ and $|1^{5/2}{D}_3⟩$ states being members of the 1D family with $J^P=1^{-}$ and $3^{-}$.

    hep-phEPJC(2017)·31 citations
14. 14*

    The 750 GeV excess from photon-photon and quark-quark processes

    Tanumoy Mandal🇸🇪 · Ulf Danielsson🇸🇪 · Rikard Enberg🇸🇪 · Gunnar Ingelman🇸🇪

    The observed excess in the diphoton mass spectrum around 750 GeV at the 13 TeV LHC possibly indicates the presence of a photonphilic resonance. We show that the excess can be explained by a scalar of the type involved in Bekenstein's framework for varying electromagnetic coupling theories. The scalar, in our model, couples dominantly to photons and is mainly produced by the quark-quark fusion at the LHC. In addition, it can also be produced in photon-photon fusion. Our model has only two free parameters, the mass of the scalar and the scale of the new physics, which are fixed by the LHC excess to 750 GeV and 1.5 - 2 TeV, respectively. The scalar has a large three-body decay to a fermion pair and a photon, which provides an interesting search channel with a dilepton-photon resonance around 750 GeV.

    hep-ph1 citation
15. 15*

    One-loop potential with scale invariance and effective operators

    D. M. Ghilencea🇷🇴

    We study quantum corrections to the scalar potential in classically scale invariant theories, using a manifestly scale invariant regularization. To this purpose, the subtraction scale $\mu$ of the dimensional regularization is generated after spontaneous scale symmetry breaking, from a subtraction function of the fields, $\mu (\varphi ,\sigma )$. This function is then uniquely determined from general principles showing that it depends on the dilaton only, with $\mu (\sigma )\sim \sigma$. The result is a scale invariant one-loop potential $U$ for a higgs field $\varphi$ and dilaton $\sigma$ that contains an additional {\it finite} quantum correction $\Delta U(\varphi ,\sigma )$, beyond the Coleman Weinberg term. $\Delta U$ contains new, non-polynomial effective operators like ${\varphi }^6/{\sigma }^2$ whose quantum origin is explained. A flat direction is maintained at the quantum level, the model has vanishing vacuum energy and the one-loop correction to the mass of $\varphi$ remains small without tuning (of its self-coupling, etc) beyond the initial, classical tuning (of the dilaton coupling) that enforces a hierarchy $⟨\sigma ⟩\gg ⟨\varphi ⟩$. The approach is useful to models that investigate scale symmetry at the quantum level.

    hep-phhep-thPoS(2016)·11 citations
16. 16*

    Lepton Flavour Violating Higgs Decays in the (SUSY) Inverse Seesaw

    E. Arganda🇦🇷 · M.J. Herrero🇪🇸 · X. Marcano🇪🇸 · C. Weiland🇬🇧

    The observation of charged lepton flavour violation would be a smoking gun for new physics and could help in pinpointing the mechanism at the origin of neutrino masses and mixing. We present here our recent studies of lepton flavour violating Higgs decays in the inverse seesaw and its supersymmetric embedding, two examples of low-scale seesaw mechanisms. We predict branching ratios as large as $10^{-5}$ for the decays $h\to \tau \mu$ and $h\to \tau e$ in the inverse seesaw, which can be probed in future colliders. Supersymmetric contributions can enhance the branching ratio of $h\to \tau \mu$ up to $1\%$, making it large enough to explain the small excess observed by ATLAS and CMS.

    hep-phhep-ex2 citations
17. 17*

    Top-Quark Properties at the LHC

    Kelly Beernaert🇩🇪

    A review of recent measurements of top-quark properties is presented. Inclusive and differential top-quark pair charge asymmetry measurements using the full Run I dataset are found to be in agreement with the standard model (SM) predictions. Results of spin correlation in top-quark pairs are presented and interpreted in terms of the SM predicted values and new physics models. Limits are set on flavour-changing neutral currents (FCNC), in particular with a Higgs boson in the final state.

    ↳ hep-exhep-ph1 citation
18. 18*

    Cosmic Neutrinos and Other Light Relics

    Joel Meyers🇨🇦

    Cosmological measurements of the radiation density in the early universe can be used as a sensitive probe of physics beyond the standard model. Observations of primordial light element abundances have long been used to place non-trivial constraints on models of new physics and to inform our understanding of the thermal history to the first few minutes of our present phase of expansion. Precision measurements of the angular power spectrum of the cosmic microwave background temperature and polarization will drastically improve our measurement of the cosmic radiation density over the next decade. These improved measurements will either uncover new physics or place much more stringent constraints on physics beyond the standard model, while pushing our understanding of the early universe to much earlier times.

    ↳ astro-ph.COhep-ph0 citations
19. 19*

    EFTfitter---A tool for interpreting measurements in the context of effective field theories

    Nuno Castro🇵🇹 · Johannes Erdmann🇩🇪 · Cornelius Grunwald🇩🇪 · Kevin Kröninger🇩🇪 · Nils-Arne Rosien🇩🇪

    Over the past years, the interpretation of measurements in the context of effective field theories has attracted much attention in the field of particle physics. We present a tool for interpreting sets of measurements in such models using a Bayesian ansatz by calculating the posterior probabilities of the corresponding free parameters numerically. An example is given, in which top-quark measurements are used to constrain anomalous couplings at the Wtb-vertex.

    ↳ hep-exhep-phEPJC(2016)·77 citations
20. 20*

    Semileptonic $B_c$ decays from full lattice QCD

    Andrew Lytle🇬🇧 · Brian Colquhoun🇬🇧 · Christine Davies🇬🇧 · Jonna Koponen🇬🇧 · Craig McNeile🇬🇧

    We present first lattice QCD results for semileptonic form factors for the decays $B_c\to {\eta }_{c}l\nu$ and $B_c\to J/\psi l\nu$ over the full $q^2$ range, using both improved non-relativistic QCD (NRQCD) and fully relativistic (HISQ) formalisms. These can be viewed as prototype calculations for pseudoscalar to pseudoscalar and pseudoscalar to vector decays involving a $b\to c$ transition. In particular we can use information from the relativistic computations to fix the NRQCD current normalisations, which can then be used in improved computations of decays such as $B\to Dl\nu$ and $B\to D^{\ast }l\nu$.

    ↳ hep-lathep-phPoS(2016)·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.