Tue·Mar 1, 2016Tuesday·March 1, 2016

1. 01*

   Dark matter relic density from observations of supersymmetry at the ILC

   Suvi-Leena Lehtinen🇩🇪 · Mikael Berggren🇩🇪 · Jenny List🇩🇪

   Supersymmetry can explain the observed dark matter relic density with a neutralino dark matter particle and a coannihilating, almost mass-degenerate sparticle. If this were the case in nature, a linear electron positron collider like the ILC could discover the two sparticles if their masses are in the kinematic reach of the collider. This contribution discusses which observations are necessary at the ILC for predicting the dark matter relic density correctly and for confirming that the observed lightest neutralino is the only kind of dark matter. We take the case of stau coannihilation as an example.

   hep-ph3 citations
2. 02*

   Prompt neutrino flux in the atmosphere revisited

   M.V. Garzelli🇩🇪 · S. Moch🇩🇪 · G. Sigl🇩🇪

   Prompt neutrino fluxes due to the interactions of high-energy cosmic rays with the Earth's atmosphere are backgrounds in the search for high-energy neutrinos of galactic or extra-galactic origin performed by Very Large Volume Neutrino Telescopes. We summarize our predictions for prompt neutrinos, showing their basic features as emerging from the calculation in a QCD framework capable of describing recent charm data from the Large Hadron Collider.

   hep-ph0 citations
3. 03*

   PeV-Scale Dark Matter as a Thermal Relic of a Decoupled Sector

   Asher Berlin🇺🇸 · Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸

   In this letter, we consider a class of scenarios in which the dark matter is part of a heavy hidden sector that is thermally decoupled from the Standard Model in the early universe. The dark matter freezes-out by annihilating to a lighter, metastable state, whose subsequent abundance can naturally come to dominate the energy density of the universe. When this state decays, it reheats the visible sector and dilutes all relic abundances, thereby allowing the dark matter to be orders of magnitude heavier than the weak scale. For concreteness, we consider a simple realization with a Dirac fermion dark matter candidate coupled to a massive gauge boson that decays to the Standard Model through its kinetic mixing with hypercharge. We identify viable parameter space in which the dark matter can be as heavy as ~1-100 PeV without being overproduced in the early universe.

   hep-phastro-ph.COPLB(2016)·166 citations
4. 04*

   A new look at the theory uncertainty of epsilon_K

   Zoltan Ligeti🇺🇸 · Filippo Sala🇫🇷

   The observable epsilon_K is sensitive to flavor violation at some of the highest scales. While its experimental uncertainty is at the half percent level, the theoretical one is in the ballpark of 15%. We explore the nontrivial dependence of the theory prediction and uncertainty on various conventions, like the phase of the kaon fields. In particular, we show how such a rephasing allows to make the short-distance contribution of the box diagram with two charm quarks, eta_cc, purely real. Our results allow to slightly reduce the total theoretical uncertainty of epsilon_K, while increasing the relative impact of the imaginary part of the long distance contribution, underlining the need to compute it reliably. We also give updated bounds on the new physics operators that contribute to epsilon_K.

   hep-phJHEP(2016)·21 citations
5. 05*

   Minimal Models of Loop-Induced Higgs Lepton Flavor Violation

   Carlos Alvarado🇺🇸 · Rodolfo M. Capdevilla🇺🇸 · Antonio Delgado🇺🇸 · Adam Martin🇺🇸

   The LHC has recently reported a slight excess in the $h\to \tau \mu$ channel. If this lepton flavor violating (LFV) decay is confirmed, an extension of the Standard Model (SM) will be required to explain it. In this paper we investigate two different possibilities to accommodate such a LFV process: the first scenario is based on flavor off-diagonal $A$-terms in the Minimal Supersymmetric Standard Model (MSSM), and the second is a model where the Higgs couples to new vectorlike fermions that couple to the SM leptons through a LFV four fermion interaction. In the supersymmetric model, we find that the sizes of the $A$-terms needed to accommodate the $h\to \tau \mu$ excess are in conflict with charge- and color-breaking vacuum constraints. In the second model, the excess can be successfully explained while satisfying all other flavor constrains, with order one couplings, vectorlike fermion masses as low as 15 TeV, and a UV scale higher than 35 TeV.

   hep-phPRD(2016)·25 citations
6. 06*

   Kaluza-Klein gluons at 100 TeV: NLO corrections

   Benjamin Lillard🇺🇸 · Tim M. P. Tait🇺🇸 · Philip Tanedo🇺🇸

   We explore the reach of a 100 TeV proton collider to discover KK gluons in a warped extra dimension. These particles are templates for color adjoint vectors that couple dominantly to the top quark. We examine their production rate at NLO in the six-flavor m-ACOT scheme for a variety of reference models defining their coupling to quarks, largely inspired by the RS model of a warped extra dimension. In agreement with previous calculations aimed at lower energy machines, we find that the NLO corrections are typically negative, resulting in a $K$-factor of around 0.7 (depending on the model) and with a residual scale dependence on the order of $\pm 20\%$, greater than the variation from the scale exhibited by the naïve LO estimate.

   hep-phPRD(2016)·6 citations
7. 07*

   Mass and decay constant of the newly observed exotic $X(5568)$ state

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

   The mass and decay constant of the $X(5568)$ state newly observed by D0 Collaboration are computed within the two-point sum rule method using the diquark-antidiquark interpolating current. In calculations, the vacuum condensates up to eight dimensions are taken into account. The obtained result for the mass of the $X(5568)$ state is in a nice agreement with the experimental data.

   hep-phhep-exhep-latPRD(2016)·85 citations
8. 08*

   Neutrino oscillations in the presence of super-light sterile neutrinos

   P. C. Divari🇬🇷 · J. D. Vergados🇬🇷

   In this paper, we study the effect of conversion of super-light sterile neutrino (SLSN) to electron neutrino in matter like that of the Earth. In the Sun the resonance conversion between SLSN and electron neutrino via the neutral current is suppressed due to the smallness of neutron number. On the other hand, neutron number density can play an important role in the Earth, making the scenario of SLSN quite interesting. The effect of CP-violating phases on active-SLSN oscillations is also discussed. Reactor neutrino experiments with medium or short baseline may probe the scenario of SLSN.

   hep-phInt.J.Mod.Phys.A(2016)·5 citations
9. 09*

   Higgs Branching Ratios in Constrained Minimal and Next-to-Minimal Supersymmetry Scenarios Surveyed

   C. Beskidt (1)🇩🇪 · W. de Boer (1)🇩🇪 · D. I. Kazakov (1,2)🇷🇺 · S. Wayand (1) ((1) Karlsruhe Institute of Technology, Germany, (2) Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia)🇩🇪

   In the CMSSM the heaviest scalar and pseudo-scalar Higgs bosons decay largely into b-quarks and tau-leptons because of the large $\tan \beta$ values favored by the relic density. In the NMSSM the number of possible decay modes is much richer. In addition to the CMSSM-like scenarios, the decay of the heavy Higgs bosons is preferentially into top quark pairs (if kinematically allowed), lighter Higgs bosons or neutralinos, leading to invisible decays. We provide a scan over the NMSSM parameter space to project the 6D parameter space of the Higgs sector on the 3D space of the Higgs masses to determine the range of branching ratios as function of the Higgs boson mass for all Higgs bosons. Specific LHC benchmark points are proposed, which represent the salient NMSSM features.

   hep-phPLB(2016)·14 citations
10. 10*

    Analysis of the $X(5568)$ as scalar tetraquark state in the diquark-antidiquark model with QCD sum rules

    Zhi-Gang Wang🇨🇳

    In this article, we take the $X(5568)$ as the diquark-antidiquark type tetraquark state with the spin-parity $J^P=0^{+}$, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value $M_X=\left(5.57\pm 0.12\right)\mathrm{GeV}$, which is consistent with the experimental data. The present prediction favors assigning the $X(5568)$ to be the scalar tetraquark state.

    hep-phCommun.Theor.Phys.(2016)·70 citations
11. 11*

    Impact of nonstandard interactions on sterile neutrino searches at IceCube

    Jiajun Liao🇺🇸 · Danny Marfatia🇺🇸

    We analyze the energy and zenith angle distributions of the latest 2-year IceCube dataset of upward going atmospheric neutrinos to constrain sterile neutrinos at the eV scale in the 3+1 scenario. We find that the parameters favored by a combination of LSND and MiniBooNE data are excluded at more than the 99% C.L. We explore the impact of nonstandard matter interactions on this exclusion, and find that the exclusion holds for nonstandard interactions (NSI) that are within the stringent model-dependent bounds set by collider and neutrino scattering experiments. However, for large NSI parameters subject only to model-independent bounds from neutrino oscillation experiments, the LSND and MiniBooNE data are consistent with IceCube.

    hep-phastro-ph.HEhep-exPRL(2016)·57 citations
12. 12*

    Can $X(5568)$ be a tetraquark state?

    Wei Wang🇨🇳 · Ruilin Zhu🇨🇳

    Very recently, the D0 collaboration has reported the observation of a narrow structure, $X(5568)$, in the decay process $X(5568)\to B_s^0{\pi }^{\pm }$ using the 10.4${\mathrm{fb}}^{-1}$ data of $p\bar{p}$ collision at $\sqrt{s}=1.96$ TeV. This structure is of great interest since it is the first hadronic state with four different valence quark flavors, $b,s,u,d$. In this work, we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor $[su][\bar{b}\bar{d}]$ and the spin-parity $J^P=0^{+}$, is about 150 MeV higher than the $X(5568)$. Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors in the future are severely needed towards a better understanding its nature and the classification of hadron exotic states.

    hep-phhep-exnucl-exnucl-thCPC(2016)·66 citations
13. 13*

    Asymmetric Dark Matter Bound State

    Xiao-Jun Bi🇨🇳 · Zhaofeng Kang🇰🇷 · P. Ko🇰🇷 · Jinmian Li🇦🇺 · Tianjun Li🇨🇳

    We propose an interesting framework for asymmetric scalar dark matter (ADM), which has novel collider phenomenology in terms of an unstable ADM bound state (ADMonium) produced via Higgs portals. ADMonium is a natural consequence of the basic features of ADM: the (complex scalar) ADM is charged under a dark local $U(1{)}_d$ symmetry which is broken at a low scale and provides a light gauge boson $X$. The dark gauge coupling is strong and then ADM can annihilate away into $X$-pair effectively. Therefore, the ADM can form bound state due to its large self-interaction via $X$ mediation. To explore the collider signature of ADMonium, we propose that ADM has a two-Higgs doublet portal. The ADMonium can have a sizable mixing with the heavier Higgs boson, which admits a large cross section of ADMonium production associated with $b\bar{b}$. The resulting signature at the LHC depends on the decays of $X$. In this paper we consider a case of particular interest: $pp\text{ra}b\bar{b}+\mathrm{ADMonium}$ followed by $\mathrm{ADMonium}\text{ra}2X\text{ra}2e^{+}{e}^{-}$ where the electrons are identified as (un)converted photons. It may provide a competitive explanation to heavy di-photon resonance searches at the LHC.

    hep-phastro-ph.COhep-exPRD(2017)·26 citations
14. 14*

    Resonances from QCD bound states and the 750 GeV diphoton excess

    Yevgeny Kats🇮🇱 · Matthew J. Strassler🇺🇸

    Pair production of colored particles is in general accompanied by production of QCD bound states (onia) slightly below the pair-production threshold. Bound state annihilation leads to resonant signals, which in some cases are easier to see than the decays of the pair-produced constituents. In a previous paper (arXiv:1204.1119) we estimated the bound state signals, at leading order and in the Coulomb approximation, for particles with various spins, color representations and electric charges, and used 7 TeV ATLAS and CMS resonance searches to set rough limits. Here we update our results to include 8 and 13 TeV data. We find that the recently reported diphoton excesses near 750 GeV could indeed be due to a bound state of this kind. A narrow resonance of the correct size could be obtained for a color-triplet scalar with electric charge -4/3 and mass near 375 GeV, if (as a recent lattice computation suggests) the wave function at the origin is somewhat larger than anticipated. Pair production of this particle could have evaded detection up to now. Other candidates may include a triplet scalar of charge 5/3, a triplet fermion of charge -4/3, and perhaps a sextet scalar of charge -2/3.

    hep-phhep-exJHEP(2016)·42 citations
15. 15*

    Antikaon-nucleon interaction and Lambda(1405) in chiral SU(3) dynamics

    Yuki Kamiya🇯🇵 · Kenta Miyahara🇯🇵 · Shota Ohnishi🇯🇵 · Yoichi Ikeda🇯🇵 · Tetsuo Hyodo🇯🇵 · Eulogio Oset🇪🇸 · Wolfram Weise🇩🇪

    The properties of the Lambda(1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Lambda(1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple three-quark picture. We show that a quantitative description of the antikaon-nucleon interaction with the Lambda(1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on the Kbar N subthreshold interaction are provided by analyzing pi Sigma spectra in various processes, such as the K-d -> pi Sigma n reaction and the Lambda_c -> pi pi Sigma decay. The structure of the Lambda(1405) is found to be dominated by an antikaon-nucleon molecular configuration, based on its wavefunction derived from a realistic Kbar N potential and the compositeness criteria from a model-independent weak-binding relation.

    hep-phnucl-thNPA(2016)·78 citations
16. 16*

    Decoding the $X(5568)$ as a fully open-flavor $su\bar{b}\bar{d}$ tetraquark state

    Wei Chen🇨🇦 · Hua-Xing Chen🇨🇳 · Xiang Liu🇨🇳 · T. G. Steele🇨🇦 · Shi-Lin Zhu🇨🇳

    We investigate the recent evidence for a charged $X(5568)$ meson as an exotic open-flavor tetraquark state $su\bar{b}\bar{d}$ with $J^P=0^{+}/1^{+}$ in the framework of QCD sum rules. We use the color antisymmetric $[{\bar{3}}_{\mathbf{c}}{]}_{su}\otimes [3_{\mathbf{c}}{]}_{\bar{b}\bar{d}}$ tetraquark currents in both scalar and axial-vector channels to perform evaluations and numerical analyses. Our results imply that the $X(5568)$ can be interpreted as both the scalar $su\bar{b}\bar{d}$ tetraquark state and the axial-vector one, which are in good agreement with the experimental measurement. We also discuss the possible decay patterns of the $X(5568)$ and suggest to search for its neutral partner in the radiative decay into $B_s^0\gamma$ and $B_s^{\ast }\gamma$, which can be used to determine its spin-parity quantum numbers. Moreover, we predict its charmed partner state around $2.55$ GeV with the quark content $su\bar{c}\bar{d}$ and $J^P=0^{+}/1^{+}$.

    hep-phhep-exhep-latnucl-exPRL(2016)·85 citations
17. 17*

    Semileptonic decays of $B_c$ meson to S-wave charmonium states in the perturbative QCD approach

    Zhou Rui🇨🇳 · Hong Li🇨🇳 · Guang-xin Wang🇨🇳 · Ying Xiao🇨🇳

    Inspired by the recent measurement of the ratio of $B_c$ branching fractions to $J/\psi {\pi }^{+}$ and $J/\psi {\mu }^{+}{\nu }_{\mu }$ final states at the LHCb detector, we study the semileptonic decays of $B_c$ meson to the S-wave ground and radially excited 2S and 3S charmonium states with the perturbative QCD approach. After evaluating the form factors for the transitions $B_c\to P,V$, where $P$ and $V$ denote pseudoscalar and vector S-wave charmonia, respectively, we calculate the branching ratios for all these semileptonic decays. The theoretical uncertainty of hadronic input parameters are reduced by utilizing the light-cone wave function for $B_c$ meson. It is found that the predicted branching ratios range from $10^{-6}$ up to $10^{-2}$ and could be measured by the future LHCb experiment. Our prediction for the ratio of branching fractions $\frac{\mathcal{B}\mathcal{R}(B_c^{+}\to J/\Psi {\pi }^{+})}{\mathcal{B}\mathcal{R}(B_c^{+}\to J/\Psi {\mu }^{+}{\nu }_{\mu })}$ is in good agreement with the data. For $B_c\to Vl{\nu }_l$ decays, the relative contributions of the longitudinal and transverse polarization are discussed in different momentum transfer squared regions. These predictions will be tested on the ongoing and forthcoming experiments.

    hep-phEPJC(2016)·62 citations
18. 18*

    $\Delta (1232)$ resonance in the $\vec{\gamma }p\to p{\pi }^0$ reaction at threshold

    A. N. Hiller Blin🇪🇸 · T. Ledwig🇪🇸 · M. J. Vicente Vacas🇪🇸

    We calculate the neutral pion photoproduction on the proton near threshold in covariant baryon chiral perturbation theory, including the $\Delta (1232)$ resonance as an explicit degree of freedom, up to chiral order $p^{7/2}$ in the $\delta$ counting. We compare our results with recent low-energy data from the Mainz Microtron for angular distributions and photon asymmetries. The convergence of the chiral series of the covariant approach is found to improve substantially with the inclusion of the $\Delta (1232)$ resonance.

    hep-phPRD(2016)·27 citations
19. 19*

    The new scattering mode emerging at the LHC?

    S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

    We point out the several experimental manifestations of the new reflective scattering mode in elastic scattering and multiparticle production at the LHC energy range.

    hep-phMod.Phys.Lett.A(2016)·27 citations
20. 20*

    Quark Matter in a Parallel Electric and Magnetic Field Background: Chiral Phase Transition and Equilibration of Chiral Density

    M. Ruggieri🇨🇳 · G. X. Peng🇨🇳

    In this article we study spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field $\mathbf{E}$ and magnetic field $\mathbf{B}$. We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at finite temperature for a wide range of $E$ and $B$. We study the effect of this background on inverse catalysis of chiral symmetry breaking for $E$ and $B$ of the same order of magnitude. We then focus on the effect of equilibration of chiral density, $n_5$, produced dynamically by axial anomaly on the critical temperature. The equilibration of $n_5$, a consequence of chirality flipping processes in the thermal bath, allows for the introduction of the chiral chemical potential, ${\mu }_5$, which is computed self-consistently as a function of temperature and field strength by coupling the number equation to the gap equation, and solving the two within an expansion in $E/T^2$, $B/T^2$ and ${\mu }_5^2/T^2$. We find that even if chirality is produced and equilibrates within a relaxation time ${\tau }_M$, it does not change drastically the thermodynamics, with particular reference to the inverse catalysis induced by the external fields, as long as the average ${\mu }_5$ at equilibrium is not too large.

    hep-phhep-latnucl-thPRD(2016)·56 citations
21. 21*

    On the light quark mass effects in Higgs boson production in gluon fusion

    Kirill Melnikov🇩🇪 · Alexander Penin🇨🇦

    Production of Higgs bosons at the LHC is affected by the contribution of light quarks, that mediate the gg \to Hg transition. Although their impact is suppressed by small Yukawa couplings, it is enhanced by large logarithms of the ratio of the Higgs boson mass or its transverse momentum to light quark masses. We study the origin of this enhancement, focusing on the abelian corrections to gg \to Hg amplitudes of the form (C_F alphas L^{2})^n, where $L \in { ln(s/mb^2), ln(p_\perp^2/mb^2) }. We show how these non-Sudakov double logarithmic terms can be resummed to all orders in the strong coupling constant. Interestingly, we find that the transverse momentum dependence of these corrections is very weak due to a peculiar cancellation between different logarithmic terms. Although the abelian part of QCD corrections is not expected to be dominant, it can be used to estimate missing higher-order corrections to light quark contributions to Higgs boson production at the LHC.

    hep-phJHEP(2016)·54 citations
22. 22*

    A QCD sum rule study for a charged bottom-strange scalar meson

    C. M. Zanetti🇧🇷 · M. Nielsen🇧🇷 · K. P. Khemchandani🇧🇷

    Using the QCD sum rule approach we investigate the possible four-quark structure for the new observed $B_s^0{\pi }^{\pm }$ narrow structure (D0). We use a diquak-antidiquark scalar current and work to the order of $m_s$ in full QCD, without relying on $1/m_Q$ expansion. Our study indicates that although it is possible to obtain a stable mass in agreement with the state found by the D0 collaboration, a more constraint analysis (simultaneous requirement of the OPE convergence and the dominance of the pole on the phenomenological side) leads to a higher mass. We also predict the masses of the bottom scalar tetraquark resonances with zero and two strange quarks.

    hep-phhep-exPRD(2016)·59 citations
23. 23*

    The relation between the NJL model and QCD with condensed gluons

    Hiroaki Kohyama🇹🇼

    We try to find the relation between the three-flavor Nambu-Jona-Lasinio model and QCD based on the hypothesis that the gluon momenta are sharply condensed around the QCD scale, \mu_g. We find that the effective four- and six-fermion interactions, G_4 and G_6, should be scaled by G_4 proportional to \mu_g^(-2) and G_6 proportional to \mu_g^(-5) being consistent with the mass dimension counting in the obtained effective Lagrangian. We then study the \mu_g dependence on the phase diagram of the chiral phase transition at finite temperature and chemical potential and the location of the critical point. We find that the location of the critical point are sensitively affected by the value of the introduced gluon energy scale.

    hep-ph5 citations
24. 24*

    SUSY at the LHC without Missing P_T

    A. S. Belyaev🇬🇧 · D. I. Kazakov🇷🇺 · A. Sperling🇷🇺

    We consider a specific class of events of the SUSY particle production at the LHC without missing p_T. Namely, we discuss the chargino pair production with a further decay into the W-boson and the neutralino when the masses of the chargino and neutralino differ by 80-90 GeV. In this case, in the final state one has two Ws and missing E_T but no missing P_T. The produced neutralinos are just boosted along Ws. For a demonstration we consider the MSSM with non-universal gaugino masses. In this case, such events are quite probable in the region of parameter space where the lightest chargino and neutralino are mostly gauginos. The excess in the W production cross-section reach about 10 % over the Standard Model background. We demonstrate that the LHC experiments, which presently measure the WW production cross section at the 8 % level can probe chargino mass around 110 GeV within the suggested scenario, which is not accessible via other searches. If the precision of WW cross section measurement at the LHC will achieve the 3 % level, then it would probe chargino masses up to about 150 GeV within the no missing P_T scenario.

    hep-ph0 citations
25. 25*

    Extending Fermi-LAT and H.E.S.S. Limits on Gamma-ray Lines from Dark Matter Annihilation

    Stefano Profumo🇺🇸 · Farinaldo S. Queiroz🇩🇪 · Carlos E. Yaguna🇩🇪

    Gamma-ray lines from dark matter annihilation ($\chi \chi \to \gamma X$, where $X=\gamma ,h,Z$) are always accompanied, at lower energies, by a continuum gamma-ray spectrum stemming both from radiative corrections ($X=\gamma$) and from the decay debris of the second particle possibly present in the final state ($X=h,Z$). This model-independent gamma-ray emission can be exploited to derive novel limits on gamma-ray lines that do not rely on the line-feature. Although such limits are not expected to be as stringent, they can be used to probe the existence of $\gamma$-ray lines for dark matter masses beyond the largest energies accessible to current telescopes. Here, we use continuous gamma-ray searches from Fermi-LAT observations of Milky Way dwarf spheroidal galaxies and from H.E.S.S. observations of the Galactic Halo to extend the limits on the annihilation cross sections into monochromatic photons to dark matter masses well beyond $500$ GeV (Fermi-LAT) and $20$ TeV (H.E.S.S.). In this large mass regime, our results provide the first constraints on $\gamma$-ray lines from dark matter annihilation.

    ↳ astro-ph.HEastro-ph.COhep-exhep-phMNRAS(2016)·32 citations
26. 26*

    Anti-dark matter: a hidden face of mirror world

    Zurab Berezhiani🇮🇹

    B and L violating interactions of ordinary particles with their twin particles from hypothetical mirror world can co-generate baryon asymmetries in both worlds in comparable amounts, ${\Omega }_B^{\prime }/{\Omega }_B\sim 5$ or so. On the other hand, the same interactions induce the oscillation phenomena between the neutral particles of two sectors which convert e.g. mirror neutrons into our antineutrons. These oscillations are environment dependent and can have fascinating physical consequences.

    ↳ astro-ph.COastro-ph.GAastro-ph.HEhep-ph19 citations
27. 27*

    Effective field theory and the scattering process for magnons in the ferromagnet, antiferromagnet, and ferrimagnet

    Shinya Gongyo🇯🇵 · Yuta Kikuchi🇯🇵 · Tetsuo Hyodo🇯🇵 · Teiji Kunihiro🇯🇵

    We discuss that a low-energy effective Lagrangian relying on SO(3) $\to$ SO(2) is applicable for a ferrimagnet as well as a ferromagnet and an antiferromagnet. The analysis of the particle states shows that there exist not only massless modes with the dispersion relations $\omega \propto |\mathbf{k}|,|\mathbf{k}{|}^2$, i.e., the so-called type-I and type-II Nambu-Goldstone modes, respectively, but also gapped modes with $\omega \propto m^2+|\mathbf{k}{|}^2$. We clarify how the coefficients of the terms with one time derivative and those with two time derivatives in the effective Lagrangian determine the order parameters specifying whether the system is in a ferromagnetic, antiferromagnetic or ferrimagnetic state; we stress that the gapped mode related to the spontaneous symmetry breaking appears only in the ferrimagnetic system and not in the ferromagnetic and antiferromagnetic systems. We also establish the power counting scheme and calculate the scattering amplitudes and thereby the scattering lengths between the two Nambu-Goldstone bosons. We show that the scattering length of the gapped mode is finite and proportional to the gap. This characteristic property of the gapped NG mode can be used to discriminate it from gapped excitations which originate in other mechanisms. Finally, we study the effects of the explicit symmetry breaking that are given by an external magnetic field and a single-ion anisotropy, and show that the external magnetic fields do not have any effects on the scattering amplitudes in all the spin systems as was known for the ferromagnet system. In contrast, the anisotropy does affect the scattering amplitudes, the phase shift, and the scattering length except for spin 1/2 systems. This result supports the possibility of the Efimov effect in spin systems discussed in previous studies.

    ↳ cond-mat.str-elcond-mat.otherhep-phnucl-thPTEP(2016)·8 citations
28. 28*

    Spin Precession of Slow Neutrons in Einstein-Cartan Gravity with Torsion, Chameleon and Magnetic Field

    A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹

    We analyse a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn (Phys. Rev. D92, 125004 (2015)) for slow neutrons, coupled to gravitational, chameleon and torsion fields to order 1/m, where m is the neutron mass. In addition to this low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor degrees of freedom. Such anti-Hermitian operators violate CP and T invariance. One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of i) violation of CP and T invariance in the Universe and ii) of baryon asymmetry.

    ↳ gr-qchep-phnucl-thquant-phPRD(2016)·12 citations
29. 29*

    Parton distribution functions from Lattice QCD

    Constantia Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾

    We present recent results on the first moments of parton distributions using gauge configurations generated with two degenerate flavors of light twisted mass quarks with pion mass fixed approximately to its physical value. We also present a first study of the vector parton distribution function using a twisted mass ensemble at pion mass of 373 MeV.

    ↳ hep-lathep-phnucl-exnucl-thFew Body Syst.(2016)·11 citations
30. 30*

    Quasiadiabatic modes from viscous inhomogeneities

    Massimo Giovannini🇨🇭

    The viscous inhomogeneities of a relativistic plasma determine a further class of entropic modes whose amplitude must be sufficiently small since curvature perturbations are observed to be predominantly adiabatic and Gaussian over large scales. When the viscous coefficients only depend on the energy density of the fluid the corresponding curvature fluctuations are shown to be almost adiabatic. After addressing the problem in a gauge-invariant perturbative expansion, the same analysis is repeated at a non-perturbative level by investigating the nonlinear curvature inhomogeneities induced by the spatial variation of the viscous coefficients. It is demonstrated that the quasiadiabatic modes are suppressed in comparison with a bona fide adiabatic solution. Because of its anomalously large tensor to scalar ratio the quasiadiabatic mode cannot be a substitute for the conventional adiabatic paradigm so that, ultimately, the present findings seems to exclude the possibility of a successful accelerated dynamics solely based on relativistic viscous fluids. If the dominant adiabatic mode is not affected by the viscosity of the background a sufficiently small fraction of entropic fluctuations of viscous origin cannot be a priori ruled out.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2016)·4 citations
31. 31*

    Inflationary universe in a conformally-invariant two scalar-field theory with an $R^2$ term

    Kazuharu Bamba🇯🇵

    We investigate the inflationary universe in a theory where two scalar fields non-minimally coupling to the scalar curvature and an extra $R^2$ term exist and the conformal invariance is broken. In particular, the slow-roll inflation is explored for the case that one scalar field is dynamical and that two scalar fields are dynamical. As a result, we show that the spectral index of the curvature perturbations and the tensor-to-scalar ratio of the density perturbations can be compatible with the Planck results. It is also demonstrated that the graceful exit from inflation can be realized.

    ↳ hep-thastro-ph.COgr-qchep-phPoS(2016)·1 citation
32. 32*

    Status and prospects for BSM ( (N)MSSM) Higgs searches at the LHC

    M.P. Casado (ATLAS and CMS collaborations)🇪🇸

    Searches for Beyond the Standard Model Higgs processes in the context of Minimal Supersymmetric Standard Model and Next to MSSM are presented. The results are based on the first LHC run of pp collision data recorded by the ATLAS and CMS experiments at the CERN Large Hadron Collider at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of about 5 and 20 fb${}^{-1}$ respectively. Current searches constrain large parts of the parameter space. No evidence for BSM Higgs is found.

    ↳ hep-exhep-ph0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.