Tue·Feb 2, 2016Tuesday·February 2, 2016

1. 01*

   Di-photon excess at LHC and the gamma ray excess at the Galactic Centre

   Andi Hektor🇪🇪 · Luca Marzola🇪🇪

   Motivated by the recent indications for a 750 GeV resonance in the di-photon final state at the LHC, in this work we analyse the compatibility of the excess with the broad photon excess detected at the Galactic Centre. Intriguingly, by analysing the parameter space of an effective models where a 750 GeV pseudoscalar particles mediates the interaction between the Standard Model and a scalar dark sector, we prove the compatibility of the two signals. We show, however, that the LHC mono-jet searches and the Fermi LAT measurements strongly limit the viable parameter space. We comment on the possible impact of cosmic antiproton flux measurement by the AMS-02 experiment.

   hep-phastro-ph.HEJCAP(2016)·20 citations
2. 02*

   Specialized minimal PDFs for optimized LHC calculations

   Stefano Carrazza🇨🇭 · Stefano Forte🇮🇹 · Zahari Kassabov🇮🇹 · Juan Rojo🇬🇧

   We present a methodology for the construction of parton distribution functions (PDFs) designed to provide an accurate representation of PDF uncertainties for specific processes or classes of processes with a minimal number of PDF error sets: specialized minimal PDF sets, or SM-PDFs. We construct these SM-PDFs in such a way that sets corresponding to different input processes can be combined without losing information, specifically on their correlations, and that they are robust upon smooth variations of the kinematic cuts. The proposed strategy never discards information, so that the SM-PDF sets can be enlarged by the addition of new processes, until the prior PDF set is eventually recovered for a large enough set of processes. We illustrate the method by producing SM-PDFs tailored to Higgs, top quark pair, and electroweak gauge boson physics, and determine that, when the PDF4LHC15 combined set is used as the prior, around 11, 4 and 11 Hessian eigenvectors respectively are enough to fully describe the corresponding processes.

   hep-phhep-exEPJC(2016)·58 citations
3. 03*

   In-Medium Y-Suppression and Feed-down in UU and PbPb Collisions

   J. Hoelck🇩🇪 · F. Nendzig🇩🇪 · G. Wolschin🇩🇪

   The suppression of Y mesons in the hot quark-gluon medium (QGP) versus reduced feed-down is investigated in UU collisions at RHIC energies and PbPb collisions at LHC energies. Our centrality- and p_T-dependent model encompasses screening, collisional damping and gluodissociation in the QGP. For Y(1S) it is in agreement with both STAR and CMS data provided the relativistic Doppler effect and the reduced feed-down from the Y(nS) and chi_b(nP) states are properly considered. At both energies, most of the Y(1S) suppression is found to be due to reduced feed-down, whereas most of the Y(2S) suppression is caused by the hot-medium effects. The role of the latter increases with energy. The p_T-dependence is flat due to the relativistic Doppler effect and reduced feed-down. We predict the Y(1S)-suppression in PbPb at sqrt(s_NN) = 5.02 TeV.

   hep-phPRC(2017)·38 citations
4. 04*

   Analytical Calculation of Radiative Corrections of a THDM Potential

   Enrique Díaz Méndez

   We obtain a closed form effective potential at the one-loop level of a Two Higgs Doublet Model. Through the loop expansion we reproduce the expression presented by Weinberg and Coleman, showing explicitly every step involved in the calculation. The formalism is then extended to include interaction terms between two scalar doublets and a final expression of the one-loop level contributions is presented.

   hep-phhep-th0 citations
5. 05*

   Continuum study on QCD phase diagram through an OPE-modified gluon propagator

   Chao Shi🇨🇳 · Yi-Lun Du🇨🇳 · Shu-Sheng Xu🇨🇳 · Xiao-Jun Liu🇨🇳 · Hong-Shi Zong🇨🇳

   Within the Dyson-Schwinger equations (DSEs) framework, a gluon propagator model incorporating quark's feedback through operator product expansion (OPE) is introduced to investigate the QCD phase diagram in the temperature--chemical-potential ($T-\mu$) plane. Partial restoration of chiral symmetry at zero temperature and finite temperature are both studied, suggesting a first order phase transition point on the $\mu$ axis and a critical end point at $(T_E,{\mu }_E)/T_c=(0.85,1.11)$, where $T_c$ is the pseudo-critical temperature. In addition, we find the pseudo-critical line can be well parameterized with the curvature parameter $\kappa$ and a consistent decrease in $\kappa$ with more of gluon propagator distributed to quark's feedback.

   hep-phPRD(2016)·33 citations
6. 06*

   First look at the PYTHIA8 hadronization program for neutrino interaction generators

   Teppei Katori🇬🇧 · Pierre Lasorak🇬🇧 · Shivesh Mandalia🇬🇧 · Ryan Terri🇬🇧

   Current and future neutrino oscillation experiments utilize information of hadronic final states to improve sensitivities on oscillation parameters measurements. Among the physics of hadronic systems in neutrino interactions, the hadronization model controls multiplicities and kinematics of final state hadrons from the primary interaction vertex. For relatively high invariant mass events, neutrino interaction generators rely on the PYTHIA6 hadronization program. Here, we show a possible improvement of this process in neutrino event generators, by utilizing expertise from the HERMES experiment. Next, we discuss the possibility to implement the PYTHIA8 program in neutrino interaction generators, including GENIE and NEUT. Finally, we show preliminary comparisons of PYTHIA8 predictions with neutrino hadron multiplicity data from bubble chamber experiments within the GENIE hadronization validation tool.

   hep-phhep-exJPS Conf.Proc.(2016)·5 citations
7. 07*

   One-loop effective lagrangians after matching

   Francisco del Aguila🇪🇸 · Zoltan Kunszt🇨🇭 · Jose Santiago🇪🇸

   We discuss the limitations of the covariant derivative expansion prescription advocated to compute the one-loop Standard Model (SM) effective lagrangian when the heavy fields couple linearly to the SM. In particular, one-loop contributions resulting from the exchange of both heavy and light fields must be explicitly taken into account through matching because the proposed functional approach alone does not account for them. We review a simple case with a heavy scalar singlet of charge $-1$ to illustrate the argument. As two other examples where this matching is needed and this functional method gives a vanishing result, up to renormalization of the heavy sector parameters, we re-evaluate the one-loop corrections to the T--parameter due to a heavy scalar triplet with vanishing hypercharge coupling to the Brout-Englert-Higgs boson and to a heavy vector-like quark singlet of charged $2/3$ mixing with the top quark, respectively. In all cases we make use of a new code for matching fundamental and effective theories in models with arbitrary heavy field additions.

   hep-phhep-exEPJC(2016)·104 citations
8. 08*

   Intrinsic strange distributions in the nucleon from the light-cone models

   Maral Salajegheh🇮🇷

   Precise knowledge of the strange and antistrange quark distributions of the nucleon is a major step toward better understanding of the strong interaction and the nucleon structure. Moreover, the $s-\bar{s}$ asymmetry in the nucleon plays an important role in some physical processes involving hadrons. The goal of this paper is the study of intrinsic strange contribution to the strange sea of the nucleon. To this aim, we calculate the intrinsic strange distributions from the various light-cone models including BHPS, scalar five-quark and meson-baryon models and then compare their results. These models can lead to the rather different distributions for the intrinsic strange that are dominated in different values of $x$. Furthermore, the meson-baryon model leads to the $s-\bar{s}$ asymmetry that can be comparable in some situations to the result obtained from the global analysis of PDFs. We also present a simple parametrization for each model prediction of intrinsic strange distribution.

   hep-phPRD(2015)·13 citations
9. 09*

   Twist Three Generalized Parton Distributions for Orbital Angular Momentum

   Abha Rajan🇺🇸 · Simonetta Liuti🇺🇸

   We study the orbital angular momentum contribution to the spin structure of the proton. It is well known that the quark and gluon spin contributions do not add up to the proton spin. We motivate the connection between the Generalized Transverse Momentum Distribution (GTMD) $F_{14}$, and orbital angular momentum by exploring the underlying quark proton helicity amplitude structure. The twist three Generalized Parton Distribution (GPD) ${\tilde{E}}_{2T}$, was shown to connect to OAM. We study these functions using a diquark model calculation. The GTMD $F_{14}$ is unique in that it can describe both Jaffe-Manohar and Ji OAM depending on choice of gauge link, i.e. whether final state interactions are included or not. We perform a calculation of $F_{14}$ in both scenarios.

   hep-phPoS(2016)·1 citation
10. 10*

    Neutrino oscillations: from an historical perspective to the present status

    S. Bilenky🇷🇺

    The history of neutrino mixing and oscillations is briefly presented. Basics of neutrino mixing and oscillations and convenient formalism of neutrino oscillations in vacuum is given. The role of neutrino in the Standard Model and the Weinberg mechanism of the generation of the Majorana neutrino masses are discussed.

    hep-phNPB(2016)·77 citations
11. 11*

    Lightness of a Higgs Boson and Spontaneous CP-violation in the Lee Model: An Alternative Scenario

    Ying-nan Mao🇨🇳 · Shou-hua Zhu🇨🇳

    Based on the weakly-coupled two-Higgs-doublet model with spontaneous CP-violation (named Lee model) and the mechanism to generate the correlation between smallness of CP-violation and lightness of scalar mass, as we proposed earlier, we predicted a light CP-mixing scalar $\eta$ in which pseudoscalar component is dominant. It is a natural scenario in which $m_{\eta }\sim \mathcal{O}(10\text{GeV})\ll v$. Masses of all other scalars ($h$, $H$, $H^{\pm }$) should be around the electro-weak scale $v$. Among them, the 125 GeV Higgs ($h$) couplings are standard-model like, and the charged Higgs ($H^{\pm }$) mass should be around the heaviest neutral scalar ($H$) mass. We discussed all experimental constraints and showed that this scenario is still allowed by data. The strictest constraints come from the experiments of the flavor-changing processes and the EDM of lepton and neutron. We also discussed the future tests for this scenario. It is possible to discover the extra scalars or exclude this scenario at future colliders, especially at the LHC and $e^{+}{e}^{-}$ colliders with $\mathcal{O}({\text{ab}}^{-1})$ luminosity. We also pointed out that the $Z$-mediated Higgs pair production via $e^{+}{e}^{-}\to h_i{h}_j$ ($h_i,h_j$ stand for two of the $\eta ,h,H$) would be the key observable to confirm or exclude CP-violation in Higgs sector. The sensitivity to test this scenario is worth further studying in greater detail.

    hep-phPRD(2016)·10 citations
12. 12*

    New gauge boson Z' and lepton flavor violating decays and production of vector mesons

    Chong-Xing Yue🇨🇳 · Jia-Rui Zhou🇨🇳

    Considering the constraints on the lepton flavor violating (LFV) couplings of the new gauge boson $Z^{\prime }$ to ordinary leptons from the experimental upper limit for the LFV process $\ell \to 3{\ell }^{\prime }$, we calculate the contributions of $Z^{\prime }$ to the LFV decays $V\to {\ell }_i{\ell }_j$ with $V\in \{\varphi ,J/\Psi ,\Psi (2S),{{\rm Y}}^{(n)}\}$ and $\tau \to \mu (e)\varphi$ in the context of several $Z^{\prime }$ models. We find that all $Z^{\prime }$ models considered in this paper can produce significant contributions to these decay processes and make the value of the branching ratio $Br(\tau \to e\varphi )$ above its experimental upper limit. The experimental upper limit of $\tau \to e\varphi$ can give more severe constraints on these $Z^{\prime }$ models than those given by the rare decay process $\tau \to 3e$.

    hep-phPRD(2016)·11 citations
13. 13*

    On the implementation of CVC in weak charged-current proton-neutron transitions

    C. Giunti🇮🇹

    It is shown that the standard expression of the vector part of the hadronic matrix element in weak charged-current proton-neutron transitions is in agreement with the CVC hypothesis, contrary to a different claim in a recent paper.

    hep-phhep-ex9 citations
14. 14*

    Study of structures and dynamical decay mechanisms for multiquark systems

    Xuewen Liu🇨🇳 · Hong-Wei Ke🇨🇳 · Xiang Liu🇨🇳 · Xue-Qian Li🇨🇳

    The inner structures of the multiquark states are an interesting subject in hadron physics, generally they may be in tetraquark states which are composed of colored constituents, or in molecular states which are composed of two color singlets, or their mixtures. Therefore, the mechanisms which bind the constituents in a unique system and induce the multiquark states to decay would be different in those cases. In this work, using the quantum mechanics we analyze the dynamical mechanisms inducing decays of the tetraquarks where $Y(4630)$ stands as an example for the study, we also comment on the molecular states without making numerical computations.

    hep-phPRD(2016)·7 citations
15. 15*

    Kondo effect in charm/bottom nuclei

    Shigehiro Yasui🇯🇵

    We discuss the Kondo effect for isospin-exchange interaction between a $\bar{D}$, $B$ meson and a valence nucleon in charm/bottom atomic nuclei including the discrete energy-levels for valence nucleons. To investigate the binding energy by the Kondo effect, we introduce the mean-field approach for the bound state of the $\bar{D}$, $B$ meson in charm/bottom nuclei. Assuming a simple model, we examine the validity of the mean-field approximation by comparing the results with the exact solutions. We also estimate the effect of the quantum fluctuation beyond the mean-field approximation. We discuss the competition between the Kondo effect and the other correlations in valence nucleon, the isospin symmetry breaking and the nucleon pairings.

    hep-phnucl-thPRC(2016)·30 citations
16. 16*

    Generalized Valon Model for Double Parton Distributions

    Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸 · Krzysztof Golec-Biernat🇵🇱

    We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.

    hep-phnucl-thFew Body Syst.(2016)·35 citations
17. 17*

    Proton-Proton On Shell Optical Potential at High Energies and the Hollownes Effect

    Enrique Ruiz Arriola🇪🇸 · Wojciech Broniowski🇵🇱

    We analyze the usefulness of the optical potential as suggested by the double spectral Mandelstam representation at very high energies, such as in the proton-proton scattering at ISR and the LHC. Its particular meaning regarding the interpretation of the scattering data up to the maximum available measured energies is discussed. Our analysis reconstructs 3D dynamics from the effective transverse 2D impact parameter representation and suggests that besides the onset of gray nucleons at the LHC there appears an inelasticity depletion (hollowness) which precludes convolution models at the attometer scale.

    hep-phnucl-thFew Body Syst.(2016)·22 citations
18. 18*

    Breakdown of QCD factorization in hard diffraction

    B.Z. Kopeliovich🇨🇱

    Factorization of short- and long-distance interactions is severely broken in hard diffractive hadronic collisions. Interaction with the spectator partons leads to an interplay between soft and hard scales, which results in a leading twist behavior of the cross section, on the contrary to the higher twist predicted by factorization. This feature is explicitly demonstrated for diffractive radiation of abelian (Drell-Yan, gauge bosons, Higgs) and non-abelian (heavy flavors) particles

    hep-phEPJ Web Conf.(2016)·0 citations
19. 19*

    Gribov inelastic shadowing in the dipole representation

    B.Z. Kopeliovich🇨🇱

    The dipole phenomenology, which has been quite successful applied to various hard reactions, especially on nuclear targets, is applied for calculation of Gribov inelastic shadowing. This approach does not include ad hoc procedures, which are unavoidable in calculations done in hadronic representation. Several examples of Gribov corrections evaluated within the dipole description are presented.

    hep-phInt.J.Mod.Phys.A(2016)·13 citations
20. 20*

    IR-improved Soft-wall AdS/QCD Model for Baryons

    Zhen Fang🇨🇳 · Dan-Ning Li🇨🇳 · Yue-Liang Wu🇨🇳

    We construct an infrared-improved soft-wall AdS/QCD model for baryons by considering the infrared-modified 5D conformal mass and Yukawa coupling of the bulk baryon field. The model is also built by taking into account the parity-doublet pattern for the excited baryons. When taking the bulk vacuum structure of the meson field to be the one obtained consistently in the infrared-improved soft-wall AdS/QCD model for mesons, we arrive at a consistent prediction for the baryon mass spectrum in even and odd parity. The prediction shows a remarkable agreement with the experimental data. We also perform a calculation for the $\rho (a_1)$ meson-nucleon coupling constant and obtain a consistent result in comparison with the experimental data and many other models.

    hep-phnucl-thPLB(2016)·28 citations
21. 21*

    Theory Summary

    Paolo Nason🇮🇹

    I review few selected topics on recent theoretical progress in top physics. In particular I will discuss recent progress in the computation of the relationship between the MS-bar and pole top mass, in the NNLO calculation of top differential distributions, and in the simulation of top production and decays. Implications for top mass measurements will be discussed.

    hep-phhep-exPoS(2016)·16 citations
22. 22*

    Hadron phenomenology from first-principle QCD studies

    J. Papavassiliou🇪🇸

    The form of the kernel that controls the dynamics of the Bethe-Salpeter equations is essential for obtaining quantitatively accurate predictions for the observable properties of hadrons. In the present work we briefly review the basic physical concepts and field-theoretic techniques employed in a first-principle derivation of a universal (process-independent) component of this kernel. This "top-down" approach combines nonperturbative ingredients obtained from lattice simulations and Dyson-Schwinger equations, and furnishes a renormalization-group invariant quark-gluon interaction strength, which is in excellent agreement with the corresponding quantity obtained from a systematic "bottom-up" treatment, where bound-state data are fitted within a well-defined truncation scheme.

    hep-phFew Body Syst.(2016)·3 citations
23. 23*

    Precision tests via radiative $\mu$ and $\tau$ leptonic decays

    M. Fael🇨🇭 · M. Passera🇮🇹

    The branching fractions of radiative leptonic $\tau$ decays $(\tau \to l\nu \bar{\nu }\gamma$, $l=e,\mu )$ were recently measured by the Babar collaboration with a relative error of about 3%. The measurement of the branching ratio $\mathcal{B}(\tau \to e\bar{\nu }\nu \gamma )$, for a minimum photon energy of 10 MeV in the $\tau$ rest frame, differs from our recent SM prediction by 3.5 standard deviations, whereas our result agrees with Babar's value for $\mathcal{B}(\tau \to \mu \bar{\nu }\nu \gamma )$. Our predictions also agree with the measurement of $\mathcal{B}(\mu \to e\bar{\nu }\nu \gamma )$ by the MEG collaboration. We also report on a recent proposal to test the $\tau$ dipole moments via precise measurements of radiative leptonic $\tau$ decays at high-luminosity $B$ factories.

    hep-phhep-exPoS(2016)·7 citations
24. 24*

    750 GeV Composite Axion as the LHC Diphoton Resonance

    Neil D. Barrie🇦🇺 · Archil Kobakhidze🇦🇺 · Matthew Talia🇦🇺 · Lei Wu🇦🇺

    We propose that the 750 GeV resonance, presumably observed in the early LHC Run 2 data, could be a heavy composite axion that results from condensation of a hypothetical quark in a high-colour representation of conventional QCD. The model, motivated by a recently proposed solution to the strong CP problem, is very economical and is essentially defined by the properties of the additional quark - its colour charge, hypercharge and mass. The axion mass and its coupling to two photons (via axial anomaly) can be computed in terms of these parameters. The axion is predominantly produced via photon fusion ($\gamma \gamma \to \mathcal{A}$) which is followed by $Z$ vector boson fusion and associated production at the LHC. We find that the total diphoton cross section of the axion can be fitted with the observed excess. Combining the requirement on the cross-section, such that it reproduces the diphoton excess events, with the bounds on the total width (${\Gamma }_{tot}⩽45$ GeV), we obtain the effective coupling in the range $1.6\times 10^{-4}$ GeV${}^{-1}\gtrsim C_{\mathcal{A}}\gtrsim 6.5\times 10^{-5}$ GeV${}^{-1}$. Within this window of allowed couplings the model favours a narrow width resonance and $y_Q^2\sim \mathcal{O}(10)$. In addition, we observe that the associated production $q\bar{q}\to \mathcal{A}\gamma \to \gamma \gamma \gamma$ can potentially produce a sizeable number of three photon events at future LHC and $e^{+}{e}^{-}$ colliders. However, the rare decay $Z\to {\mathcal{A}}^{\ast }\gamma \to \gamma \gamma \gamma$ is found to be too small to be probed at the LHC.

    hep-phPLB(2016)·52 citations
25. 25*

    Fate of Electroweak Vacuum during Preheating

    Yohei Ema🇯🇵 · Kyohei Mukaida🇯🇵 · Kazunori Nakayama🇯🇵

    Our electroweak vacuum may be metastable in light of the current experimental data of the Higgs/top quark mass. If this is really the case, high-scale inflation models require a stabilization mechanism of our vacuum during inflation. A possible candidate is the Higgs-inflaton/-curvature coupling because it induces an additional mass term to the Higgs during the slow roll regime. However, after the inflation, the additional mass term oscillates, and it can potentially destabilize our electroweak vacuum via production of large Higgs fluctuations during the inflaton oscillation era. In this paper, we study whether or not the Higgs-inflaton/-curvature coupling can save our vacuum by properly taking account of Higgs production during the preheating stage. We put upper bounds on the Higgs-inflaton/-curvature coupling, and discuss possible dynamics that might relax them.

    hep-phastro-ph.COJCAP(2016)·83 citations
26. 26*

    Tests of Lorentz and CPT symmetry with hadrons and nuclei

    J. P. Noordmans🇵🇹 · J. de Vries🇳🇱 · R. G. E. Timmermans🇳🇱

    We explore the breaking of Lorentz and CPT invariance in strong interactions at low energy in the framework of chiral perturbation theory. Starting from the set of Lorentz-violating operators of mass-dimension five with quark and gluon fields, we construct the effective chiral Lagrangian with hadronic and electromagnetic interactions induced by these operators. We develop the power-counting scheme and discuss loop diagrams and the one-pion-exchange nucleon-nucleon potential. The effective chiral Lagrangian is the basis for calculations of low-energy observables with hadronic degrees of freedom. As examples, we consider clock-comparison experiments with nuclei and spin-precession experiments with nucleons in storage rings. We derive strict limits on the dimension-five tensors that quantify Lorentz and CPT violation.

    hep-phnucl-thPRC(2016)·26 citations
27. 27*

    Tau-decay hadronic spectral functions: probing quark-hadron duality

    C. A. Dominguez🇿🇦 · L. A. Hernandez🇿🇦 · K. Schilcher🇿🇦 · H. Spiesberger🇩🇪

    The vector and axial-vector ALEPH hadronic spectral functions from $\tau$-decay are used to probe potential quark-hadron duality violations (DV). This is done in the framework of finite energy QCD sum rules (FESR). A pinched integration kernel is introduced in the FESR in order to (a) quench potential duality violations on the real axis in the complex squared energy $s$-plane, and (b) effectively extend the analysis well beyond the kinematical $\tau$-decay end-point where there is no longer data, i.e.\ in the range $s=3-10{\text{mbox}GeV}^2$. In the vector channel this procedure is supplemented with actual data from $e^{+}{e}^{-}$-annihilation into hadrons, above the tau-decay kinematical end-point, with results fully supporting this extension. Very good agreement is obtained between data and two specific pinched FESR. Results from this analysis are confronted with those from a specific model of DV. As the sum rules are well satisfied in both cases within experimental errors, we conclude that possible DV must be buried under the experimental uncertainties. In other words, there seems to be no need for explicit models of DV in this case. Pinched kernels work as well, but with far less free parameters.

    hep-ph6 citations
28. 28*

    Large Extra Dimensions at LHC Run 2

    Giorgio Busoni🇦🇺

    I extract new limits on the coefficient of the effective operator generated by tree-level graviton exchange in large extra dimensions from $pp\to jj$ angular distributions at LHC: $M_T>6.8$ TeV (CMS after $2.6f{b}^{-1}$ of integrated luminosity) and $M_T>8.3$ TeV (ATLAS after $3.6f{b}^{-1}$). I also compare such limits to the ones obtained using the full graviton amplitude, and discuss the impact of additional constrains arising from other datasets, such as Mono-Jet.

    hep-ph1 citation
29. 29*

    Kinetic theory of a longitudinally expanding system

    Francois Gelis🇫🇷

    We use kinetic theory in order to study the role of quantum fluctuations in the isotropization of the pressure tensor in a system subject to fast longitudinal expansion, such as the matter produced in the early stages of a heavy ion collision.

    hep-phnucl-thEPJ Web Conf.(2016)·0 citations
30. 30*

    Reconstructing semi-invisible events in resonant tau pair production from Higgs

    Partha Konar🇮🇳 · Abhaya Kumar Swain🇮🇳

    We study the possibility of utilising the constrained mass variable, $M_{2Cons}$, in reconstructing the semi-invisible events originated from a resonant production at the LHC. While this proposal is effective for any similar antler type production mechanism, here we demonstrate with potentially interesting scenario, when the Higgs boson decays into a pair of third generation $\tau$ leptons. Buoyed with a relatively large Yukawa coupling, the LHC has already started exploring this pair production to investigate the properties of Higgs in the leptonic sector. Dominant signatures through hadronic decay of tau, associated with invisible neutrinos compound the difficulty in the reconstruction of such events. Exploiting the already existing Higgs mass bound, this new method provides a unique event reconstruction, together with a significant enhancement in terms of efficiency over the existing methods.

    hep-phhep-exPLB(2016)·18 citations
31. 31*

    3-Loop Corrections to the Heavy Flavor Wilson Coefficients in Deep-Inelastic Scattering

    J. Ablinger🇦🇹 · A. Behring🇩🇪 · J. Blümlein🇩🇪 · A. De Freitas🇩🇪 · A. Hasselhuhn🇩🇪 · A. von Manteuffel🇩🇪 · C.G. Raab🇦🇹 · M. Round🇦🇹 · C. Schneider🇦🇹 · F. Wißbrock🇩🇪

    A survey is given on the status of 3-loop heavy flavor corrections to deep-inelastic structure functions at large enough virtualities $Q^2$.

    hep-phhep-exPoS(2015)·6 citations
32. 32*

    The case for 100 GeV bino dark matter: A dedicated LHC tri-lepton search

    Melissa van Beekveld🇳🇱 · Wim Beenakker🇳🇱 · Sascha Caron🇳🇱 · Roberto Ruiz de Austri🇪🇸

    Global fit studies performed in the pMSSM and the photon excess signal originating from the Galactic Center seem to suggest compressed electroweak supersymmetric spectra with a $\sim$100 GeV bino-like dark matter particle. We find that these scenarios are not probed by traditional electroweak supersymmetry searches at the LHC. We propose to extend the ATLAS and CMS electroweak supersymmetry searches with an improved strategy for bino-like dark matter, focusing on chargino plus next-to-lightest neutralino production, with a subsequent decay into a tri-lepton final state. We explore the sensitivity for pMSSM scenarios with $\Delta m=m_{\mathrm{NLSP}}-m_{\mathrm{LSP}}\sim (5-50)$ GeV in the $\sqrt{s}=14$ TeV run of the LHC. Counterintuitively, we find that the requirement of low missing transverse energy increases the sensitivity compared to the current ATLAS and CMS searches. With 300 fb${}^{-1}$ of data we expect the LHC experiments to be able to discover these supersymmetric spectra with mass gaps down to $\Delta m\sim 9$ GeV for DM masses between 40 and 140 GeV. We stress the importance of a dedicated search strategy that targets precisely these favored pMSSM spectra.

    hep-phastro-ph.HEhep-exJHEP(2016)·24 citations
33. 33*

    Ordering multiple soft gluon emissions

    René Ángeles-Martínez🇬🇧 · Jeffrey R. Forshaw🇬🇧 · Michael H. Seymour🇬🇧

    We present an expression for the QCD amplitude for a general hard scattering process with any number of soft gluon emissions, to one-loop accuracy. The amplitude is written in two different but equivalent ways: as a product of operators ordered in dipole transverse momentum and as a product of loop-expanded currents. We hope that these results will help in the development of an all-orders algorithm for multiple emissions that includes the full colour structure and both the real and imaginary contributions to the amplitude.

    hep-phPRL(2016)·19 citations
34. 34*

    Radiative Breaking of the Minimal Supersymmetric Left-Right Model

    Nobuchika Okada🇺🇸 · Nathan Papapietro🇺🇸

    We study a variation to the SUSY Left-Right symmetric model based on the gauge group $SU(3{)}_c\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{BL}$. Beyond the quark and lepton superfields we only introduce a second Higgs bidoublet to produce realistic fermion mass matrices. This model does not include any $SU(2{)}_R$ triplets. We calculate renormalization group evolutions of soft SUSY parameters at the one-loop level down to low energy. We find that an $SU(2{)}_R$ slepton doublet acquires a negative mass squared at low energies, so that the breaking of $SU(2{)}_R\times U(1{)}_{BL}\to U(1{)}_Y$ is realized by a non-zero vacuum expectation value of a right-handed sneutrino. Small neutrino masses are produced through neutrino mixings with gauginos. Mass limits on the $SU(2{)}_R\times U(1{)}_{BL}$ sector are obtained by direct search results at the LHC as well as lepton-gaugino mixing bounds from the LEP precision data.

    hep-phPLB(2016)·3 citations
35. 35*

    Probing CP violation in $e^{+}{e}^{-}$ production of the Higgs boson and toponia

    Kaoru Hagiwara🇯🇵 · Kai Ma🇨🇳 · Hiroshi Yokoya🇰🇷

    We study the CP violation in the Higgs boson and toponia production process at the ILC where the toponia are produced near the threshold. With the approximation that the production vertex of the Higgs boson and toponia is contact, and neglecting the P-wave toponia, we analytically calculated the density matrix for the production and decay of the toponia. Under these assumptions, the production spectrum of the toponia is solely determined by the spin quantum number, therefore the toponia can be either singlet or triplet. We find that the production rate of the singlet toponium is highly suppressed, and behaves just like the production of a P-wave toponia. In the case of the triplet toponium, three completely independent CP observables, namely azimuthal angles of lepton and anti-lepton in the toponium rest-frame as well as their sum, are predicted based on our analytical results, and checked by using the tree-level event generator. The non-trivial correlations come from the longitudinal-transverse interferences for the azimuthal angles of leptons, and the transverse-transverse interference for their sum. These three observables are well defined at the ILC, where the rest frame of the toponium can be reconstructed directly. Furthermore, the QCD-strong corrections, which are important near the threshold region, are also studied with the approximation of spin-independent QCD-Coulomb potential. While the total cross section is enhanced, the spin correlations predicted in this paper are not affected.

    hep-phhep-exJHEP(2016)·31 citations
36. 36*

    New Spectral Features from Bound Dark Matter

    Riccardo Catena🇸🇪 · Chris Kouvaris🇩🇰

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section.

    ↳ astro-ph.COhep-phPRD(2016)·7 citations
37. 37*

    Experimental Searches for the Axion and Axion-like Particles

    Peter W. Graham🇺🇸 · Igor G. Irastorza🇪🇸 · Steven K. Lamoreaux🇺🇸 · Axel Lindner🇩🇪 · Karl A. van Bibber🇺🇸

    Four decades after its prediction, the axion remains the most compelling solution to the Strong-CP problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing. This report reviews the experimental situation on several fronts. The microwave cavity experiment is making excellent progress in the search for dark matter axions in the microelectronvolt range and may be plausibly extended up to 100 mu eV. Within the past several years however, it has been realized that axions are pervasive throughout string theories, but with masses that fall naturally in the nanoelectronvolt range, for which a NMR-based search is under development. Searches for axions emitted from the Sun's burning core, and purely laboratory experiments based on photon regeneration have both made great strides in recent years, with ambitious projects proposed for the coming decade. Each of these campaigns has pushed the state of the art in technology, enabling large gains in sensitivity and mass reach. Furthermore each modality has also been exploited to search for more generalized axion-like particles, that will also be discussed in this report. We are hopeful, even optimistic, that the next review of the subject will concern the discovery of the axion, its properties, and its exploitation as a probe of early universe cosmology and structure formation.

    ↳ hep-exastro-ph.COhep-phAnn.Rev.Nucl.Part.Sci.(2015)·893 citations
38. 38*

    Violation of the Leggett-Garg Inequality in Neutrino Oscillations

    J. A. Formaggio🇺🇸 · D. I. Kaiser🇺🇸 · M. M. Murskyj🇺🇸 · T. E. Weiss🇺🇸

    The Leggett-Garg inequality, an analogue of Bell's inequality involving correlations of measurements on a system at different times, stands as one of the hallmark tests of quantum mechanics against classical predictions. The phenomenon of neutrino oscillations should adhere to quantum-mechanical predictions and provide an observable violation of the Leggett-Garg inequality. We demonstrate how oscillation phenomena can be used to test for violations of the classical bound by performing measurements on an ensemble of neutrinos at distinct energies, as opposed to a single neutrino at distinct times. A study of the MINOS experiment's data shows a greater than $6\sigma$ violation over a distance of 735 km, representing the longest distance over which either the Leggett-Garg inequality or Bell's inequality has been tested.

    ↳ quant-phhep-phPRL(2016)·150 citations
39. 39*

    Modified Dark Matter

    Y. Jack Ng🇺🇸 · Doug Edmonds🇺🇸 · Duncan Farrah🇺🇸 · Djordje Minic🇺🇸 · Tatsu Takeuchi🇺🇸 · Chiu Man Ho🇺🇸

    Modified dark matter (MDM, formerly known as MoNDian dark matter) is a phenomenological model of dark matter, inspired by quantum gravity. We review the construction of MDM by generalizing entropic gravity to de-Sitter space as is appropriate for an accelerating universe (in accordance with the Lambda-CDM model). Unlike cold dark matter models, the MDM mass profile depends on the baryonic mass. We successfully fit the rotation curves to a sample of 30 local spiral galaxies with a single free parameter (viz., the mass-to-light ratio for each galaxy). We show that dynamical and observed masses agree in a sample of 93 galactic clusters. We also comment on strong gravitational lensing in the context of MDM.

    ↳ astro-ph.COgr-qchep-ph7 citations
40. 40*

    Counting master integrals: Integration by parts vs. functional equations

    Bernd A. Kniehl🇩🇪 · Oleg V. Tarasov🇩🇪

    We illustrate the usefulness of functional equations in establishing relationships between master integrals under the integration-by-parts reduction procedure by considering a certain two-loop propagator-type diagram as an example.

    ↳ hep-thhep-phmath-phmath.MP4 citations
41. 41*

    Evidence for Non-Exponential Differential Cross-Section of pp Elastic Scattering at Low |t| and $\sqrt{s}$ = 8 TeV by TOTEM

    T. Csörgő (for the TOTEM Collaboration)🇭🇺

    Recently published and preliminary results of the TOTEM experiment are presented, emphasizing a recent discovery of a non-exponential behaviour of the differential cross-section of elastic proton-proton scattering, that TOTEM measured with an unprecedented precision at the centre-of-mass energy $\sqrt{s}$ = 8 TeV based on a high-statistics data sample obtained with the ${\beta }_{\ast }=90$ m optics of CERN LHC. Both the statistical and systematic uncertainties remained below 1%, except for the t-independent contribution from the overall normalisation. This measurement allowed TOTEM to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV${}^2$ with a significance greater than 7 $\sigma$. In this context we also highlight the innovative TOTEM recalibration of LHC optics, that used elastic scattering data measured by the world's largest and most complex Roman Pot detector system, and discuss recent preliminary TOTEM data on the Coulomb-Nuclear interference region with its physics implications.

    ↳ hep-exhep-phEPJ Web Conf.(2016)·8 citations
42. 42*

    Electron-neutrino scattering off nuclei from two different theoretical perspectives

    M. Martini🇧🇪 · N. Jachowicz🇧🇪 · M. Ericson🇨🇭 · V. Pandey🇧🇪 · T. Van Cuyck🇧🇪 · N. Van Dessel🇧🇪

    We analyze charged-current electron-neutrino cross sections on Carbon. We consider two different theoretical approaches, on one hand the Continuum Random Phase Approximation (CRPA) which allows a description of giant resonances and quasielastic excitations, on the other hand the RPA-based calculations which are able to describe multinucleon emission and coherent and incoherent pion production as well as quasielastic excitations. We compare the two approaches in the genuine quasielastic channel, and find a satisfactory agreement between them at large energies while at low energies the collective giant resonances show up only in the CRPA approach. We also compare electron-neutrino cross sections with the corresponding muon-neutrino ones in order to investigate the impact of the different charged-lepton masses. Finally, restricting to the RPA-based approach we compare the sum of quasielastic, multinucleon emission, coherent and incoherent one-pion production cross sections (folded with the electron-neutrino T2K flux) with the charged-current inclusive electron-neutrino differential cross sections on Carbon measured by T2K. We find a good agreement with the data. The multinucleon component is needed in order to reproduce the T2K electron-neutrino inclusive cross sections.

    ↳ nucl-thhep-exhep-phPRC(2016)·78 citations
43. 43*

    The B-mode polarization of CMB and Cosmic Neutrino Background

    Rohoollah Mohammadi🇮🇷 · Jafar Khodagholizadeh🇮🇷 · Mahdi Sadegh🇮🇷 · She-Sheng Xue🇮🇹

    It is known that in contrast with the E-mode polarization, the B-mode polarization of the Cosmic Microwave Background cannot be generated by the Compton scattering in the case of scalar mode of metric perturbation. However it is possible to generate the B-mode by the Compton scattering in the case of tensor mode of metric perturbation. For this reason, the ratio of tensor to scalar modes of metric perturbation ($r\sim C_{Bl}/C_{El}$) is estimated by comparing the B-mode power spectrum with the E-mode at least for small $l$. We study the CMB polarization specially B-mode due to the weak interaction of Cosmic Neutrino Background (CNB) and CMB, in addition to the Compton scattering in both cases of scalar and tensor metric perturbations. It is shown that the power spectrum $C_{Bl}$ of the B-mode polarization receives some contributions from scalar and tensor modes, which have effects on the value of $r$-parameter. We also show that the B-mode polarization power spectrum can be used as an indirect probe into the CNB.

    ↳ astro-ph.COgr-qchep-phPRD(2016)·17 citations
44. 44*

    Elastic $\alpha$-${}^{12}$C scattering at low energies in cluster effective field theory

    Shung-Ichi Ando (Sunmoon U.)🇰🇷

    The elastic $\alpha$-${}^{12}$C scattering at low energies is studied employing an effective field theory in which the $\alpha$ and ${}^{12}$C states are treated as elementary-like fields. We discuss scales of the theory at stellar energy region that the ${}^{12}$C($\alpha$, $\gamma$)${}^{16}$O process occurs, and then obtain an expression of the elastic scattering amplitudes in terms of effective range parameters. Using experimental data of the phase shifts for $l=0,1,2$ channels at low energies, for which the resonance regions are avoided, we fix values of the parameters and find that the phase shifts at the low energies are well reproduced by using three effective range parameters for each channel. Furthermore, we discuss problems and uncertainties of the present approach when the amplitudes are extrapolated to the stellar energy region.

    ↳ nucl-thhep-phnucl-exEPJA(2016)·33 citations
45. 45*

    Low Scale Higgs Inflation with Gauss-Bonnet Coupling

    Jose Mathew (IISER-TVM)🇮🇳 · S. Shankaranarayanan (IISER-TVM)🇮🇳

    Recent LHC data provides precise values of coupling constants of the Higgs field, however, these measurements do not determine its coupling with gravity. We explore this freedom to see whether Higgs field non-minimally coupled to Gauss-Bonnet term in 4-dimensions can lead to inflation generating the observed density fluctuations. We obtain analytical solution for this model and that the exit of inflation (with a finite number of e-folding) demands that the energy scale of inflation is close to Electro-weak scale. We compare the scalar and tensor power spectrum of our model with PLANCK data and discuss its implications.

    ↳ astro-ph.COhep-phhep-thAstropart.Phys.(2016)·35 citations
46. 46*

    Top-quark mass measurements at the LHC: alternative methods

    Marcel Vos (ATLAS and CMS collaborations)🇪🇸

    Alternative top quark mass determinations can provide inputs to the world average with orthogonal systematic uncertainties and may help to refine the interpretation of the standard method. Among a number of recent results I focus on the extractions by ATLAS and CMS of the top quark pole mass from the top quark pair and tt + 1 jet production cross-section, which have now reached a precision of 1%.

    ↳ hep-exhep-phPoS(2016)·8 citations
47. 47*

    Dark Forces Searches at KLOE-2

    Elena Perez del Rio (for the KLOE-2 Collaboration)🇮🇹

    Direct searches of dark matter are performed at accelerator facilities. The existence of a new vector boson has been postulated in different scenarios where in the most basic scheme the coupling to the SM can be achieved via a kinetic mixing term due to the U boson. The KLOE experiment at DA$\varphi$NE searched for the U boson both in Dalitz decays of the $\varphi$ meson and in continuum events. For all of these searches an upper limit for the U boson coupling ${ϵ}^2$ has been established in the mass range $50\text{MeV}<m_U<1000\text{MeV}$. A summary of the different models and searches along with results are presented.

    ↳ hep-exhep-phActa Phys.Polon.B(2016)·11 citations
48. 48*

    Derivation of anisotropic dissipative fluid dynamics from the Boltzmann equation

    E. Molnar🇩🇪 · H. Niemi🇩🇪 · D. H. Rischke🇩🇪

    Fluid-dynamical equations of motion can be derived from the Boltzmann equation in terms of an expansion around a single-particle distribution function which is in local thermodynamical equilibrium, i.e., isotropic in momentum space in the rest frame of a fluid element. However, in situations where the single-particle distribution function is highly anisotropic in momentum space, such as the initial stage of heavy-ion collisions at relativistic energies, such an expansion is bound to break down. Nevertheless, one can still derive a fluid-dynamical theory, called anisotropic dissipative fluid dynamics, in terms of an expansion around a single-particle distribution function, ${\hat{f}}_{0\mathbf{k}}$, which incorporates (at least parts of) the momentum anisotropy via a suitable parametrization. We construct such an expansion in terms of polynomials in energy and momentum in the direction of the anisotropy and of irreducible tensors in the two-dimensional momentum subspace orthogonal to both the fluid velocity and the direction of the anisotropy. From the Boltzmann equation we then derive the set of equations of motion for the irreducible moments of the deviation of the single-particle distribution function from ${\hat{f}}_{0\mathbf{k}}$. Truncating this set via the 14-moment approximation, we obtain the equations of motion of anisotropic dissipative fluid dynamics.

    ↳ nucl-thhep-phphysics.flu-dynPRD(2016)·98 citations
49. 49*

    Investigation of pionic contribution in the lepton and anti-lepton production cross section in p-Cu and p-Pt collision

    R. Rostami🇮🇷 · F. Zolfagharpour🇮🇷

    For detailed explanation of the experimental results of lepton production cross section in hadronic collisions such as nucleon-nucleon or nucleon-nuclei, it is of great importance to use quarks and sea quarks distribution function inside free and bound nucleons. In this paper the role of pion cloud inside the nucleus in the structure function of Cu and Pt nuclei and the EMC ratio of these nuclei were investigated by using harmonic oscillator model.

    ↳ nucl-thhep-phAdv.High Energy Phys.(2016)·0 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.