Mon·Apr 11, 2016Monday·April 11, 2016

1. 01*

   Neutrino-nucleon cross sections at energies of Megaton-scale detectors

   A. Gazizov🇩🇪 · M. Kowalski🇩🇪 · K. S. Kuzmin🇷🇺 · V. A. Naumov🇷🇺 · Ch. Spiering🇩🇪

   An updated set of (anti)neutrino-nucleon charged and neutral current cross sections at $3\mathrm{GeV}\lesssim E_{\nu }\lesssim 100\mathrm{GeV}$ is presented. These cross sections are of particular interest for the detector optimization and data processing and interpretation in the future Megaton-scale experiments like PINGU, ORCA, and Hyper-Kamiokande. Finite masses of charged leptons and target mass corrections in exclusive and deep inelastic $(\bar{\nu })\nu N$ interactions are taken into account. A new set of QCD NNLO parton density functions, the ABMP15, is used for calculation of the DIS cross sections. The sensitivity of the cross sections to phenomenological parameters and to extrapolations of the nucleon structure functions to small $x$ and $Q^2$ is studied. An agreement within the uncertainties of our calculations with experimental data is demonstrated.

   hep-phEPJ Web Conf.(2016)·14 citations
2. 02*

   Naturalness of MSSM dark matter

   Maria Eugenia Cabrera🇧🇷 · J. Alberto Casas🇪🇸 · Antonio Delgado🇺🇸 · Sandra Robles🇪🇸 · Roberto Ruiz de Austri🇪🇸

   There exists a vast literature examining the electroweak (EW) fine-tuning problem in supersymmetric scenarios, but little concerned with the dark matter (DM) one, which should be combined with the former. In this paper, we study this problem in an, as much as possible, exhaustive and rigorous way. We have considered the MSSM framework, assuming that the LSP is the lightest neutralino, ${\chi }_1^0$, and exploring the various possibilities for the mass and composition of ${\chi }_1^0$, as well as different mechanisms for annihilation of the DM particles in the early Universe (well-tempered neutralinos, funnels and co-annihilation scenarios). We also present a discussion about the statistical meaning of the fine-tuning and how it should be computed for the DM abundance, and combined with the EW fine-tuning. The results are very robust and model-independent and favour some scenarios (like the h-funnel when $M_{{\chi }_1^0}$ is not too close to $m_h/2$) with respect to others (such as the pure wino case). These features should be taken into account when one explores "natural SUSY" scenarios and their possible signatures at the LHC and in DM detection experiments.

   hep-phJHEP(2016)·33 citations
3. 03*

   String completion of an $\mathrm{SU}(3{)}_{\mathrm{c}}\otimes \mathrm{SU}(3{)}_{\mathrm{L}}\otimes \mathrm{U}(1{)}_{\mathrm{X}}$ electroweak model

   Andrea Addazi🇮🇹 · J. W. F. Valle🇪🇸 · C. A. Vaquera-Araujo🇪🇸

   The extended electroweak $\mathrm{SU}(3{)}_{\mathrm{c}}\otimes \mathrm{SU}(3{)}_{\mathrm{L}}\otimes \mathrm{U}(1{)}_{\mathrm{X}}$ symmetry framework "explaining" the number of fermion families is revisited. While $331$-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (un)oriented open strings, on Calabi-Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron-antineutron oscillations, with proton decay and other dangerous R-parity violating processes strictly forbidden.

   hep-phhep-thPLB(2016)·34 citations
4. 04*

   Bottom-Tau Unification in Supersymmetric Model with Anomaly-Mediation

   So Chigusa🇯🇵 · Takeo Moroi🇯🇵

   We study the Yukawa unification, in particular, the unification of the Yukawa coupling constants of $b$ and $\tau$, in the framework of supersymmetric (SUSY) model. We concentrate on the model in which the SUSY breaking scalar masses are of the order of the gravitino mass while the gaugino masses originate from the effect of anomaly mediation and hence are one-loop suppressed relative to the gravitino mass. We perform an accurate calculation of the Yukawa coupling constants of $b$ and $\tau$ at the grand unified theory (GUT) scale, including relevant renormalization group effects and threshold corrections. In particular, we study the renormalization group effects, taking into account the mass splittings among sfermions, gauginos, and the standard model particles. We found that the Yukawa coupling constant of $b$ at the GUT scale is about $70\%$ of that of $\tau$ if there is no hierarchy between the sfermion masses and the gravitino mass. Our results suggest sizable threshold corrections to the Yukawa coupling constants at the GUT scale or significant suppressions of the sfermion masses relative to the gravitino mass.

   hep-phPRD(2016)·4 citations
5. 05*

   Diphoton Resonances in the Renormalizable Coloron Model

   R. Sekhar Chivukula🇺🇸 · Arsham Farzinnia🇰🇷 · Kirtimaan Mohan🇺🇸 · Elizabeth H. Simmons🇺🇸

   The renormalizable coloron model, which has previously been shown in the literature to be consistent with a wide array of theoretical and precision electroweak constraints, includes a pair of spinless bosons (one scalar, one pseudoscalar). We show that either of them, or both together if they are degenerate, could be responsible for the diphoton resonance signal for which both CMS and ATLAS have seen evidence. Because either of these bosons would be produced and decay through loops of spectator fermions, the absence of signals in dijet, $t\bar{t}$, and electroweak boson pair channels is not a surprise.

   hep-phhep-exPRD(2016)·12 citations
6. 06*

   A new approach to the Higgs transverse-momentum resummation at NNLL+NNLO

   Pier Francesco Monni🇬🇧 · Emanuele Re🇫🇷 · Paolo Torrielli🇮🇹

   We propose a new approach to the resummation of the transverse-momentum distribution of a high-mass colour-singlet system in hadronic collisions. The resummation is performed in momentum space and is free of kinematic singularities at small transverse momentum. We derive a formula accurate at the next-to-next-to-leading-logarithmic level, and present the first matched predictions to next-to-next-to-leading order for Higgs-boson production in gluon fusion at the LHC. This method can be adapted to all observables featuring kinematic cancellations in the infrared region.

   hep-phhep-exPRL(2016)·141 citations
7. 07*

   Effective Theory of WIMP Dark Matter supplemented by Simplified Models: Singlet-like Majorana fermion case

   Shigeki Matsumoto🇯🇵 · Satyanarayan Mukhopadhyay🇺🇸 · Yue-Lin Sming Tsai🇯🇵

   We enumerate the set of simplified models which match onto the complete set of gauge invariant effective operators up to dimension six describing interactions of a singlet-like Majorana fermion dark matter with the standard model. Tree level matching conditions for each case are worked out in the large mediator mass limit, defining a one to one correspondence between the effective operator coefficients and the simplified model parameters for weakly interacting models. Utilizing such a mapping, we compute the dark matter annihilation rate in the early universe, as well as other low-energy observables like nuclear recoil rates using the effective operators, while the simplified models are used to compute the dark matter production rates at high energy colliders like LEP, LHC and future lepton colliders. Combining all relevant constraints with a profile likelihood analysis, we then discuss the currently allowed parameter regions and prospects for future searches in terms of the effective operator parameters, reducing the model dependence to a minimal level. In the parameter region where such a model-independent analysis is applicable, and leaving aside the special dark matter mass regions where the annihilation proceeds through an s-channel Z or Higgs boson pole, the current constraints allow effective operator suppression scales ($\Lambda$) of the order of a few hundred GeV for dark matter masses $m_{\chi }>$ 20 GeV at $95\%$ C.L., while the maximum allowed scale is around $3$ TeV for $m_{\chi }\sim \mathcal{O}(1\mathrm{TeV})$. An estimate of the future reach of ton-scale direct detection experiments and planned electron-positron colliders show that most of the remaining regions can be probed, apart from dark matter masses near half of the Z-boson mass (with $500\mathrm{GeV}<\Lambda <2\mathrm{TeV}$) and those beyond the kinematic reach of the future lepton colliders.

   hep-phPRD(2016)·60 citations
8. 08*

   Constraining particle dark matter using local galaxy distribution

   Shin'ichiro Ando🇳🇱 · Koji Ishiwata🇯🇵

   It has been long discussed that cosmic rays may contain signals of dark matter. In the last couple of years an anomaly of cosmic-ray positrons has drawn a lot of attentions, and recently an excess in cosmic-ray anti-proton has been reported by AMS-02 collaboration. Both excesses may indicate towards decaying or annihilating dark matter with a mass of around 1-10 TeV. In this article we study the gamma rays from dark matter and constraints from cross correlations with distribution of galaxies, particularly in a local volume. We find that gamma rays due to inverse-Compton process have large intensity, and hence they give stringent constraints on dark matter scenarios in the TeV scale mass regime. Taking the recent developments in modeling astrophysical gamma-ray sources as well as comprehensive possibilities of the final state products of dark matter decay or annihilation into account, we show that the parameter regions of decaying dark matter that are suggested to explain the excesses are excluded. We also discuss the constrains on annihilating scenarios.

   hep-phastro-ph.COJCAP(2016)·23 citations
9. 09*

   Generation of hypermagnetic helicity and leptogenesis in early universe

   V.B. Semikoz🇷🇺 · Alexander Yu. Smirnov🇷🇺 · D.D. Sokoloff🇷🇺

   We study hypermagnetic helicity and lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law $B/3-L_{eR}=const$ at temperatures $T>T_{RL}\simeq 10TeV$ the following universe cooling leads to the production of a non-zero left lepton (electrons and neutrinos) asymmetry. This is due to the Higgs decays becoming more faster when entering the equilibrium at $T=T_{RL}$ with the universe expansion, ${\Gamma }_{RL}\sim T>H\sim T^2$ , resulting in the parallel evolution of the right and the left electron asymmetries at $T<T_{RL}$ through the corresponding Abelian anomalies in SM in the presence of a seed hypermagnetic field. The hypermagnetic helicity evolution proceeds in a self-consistent way with the lepton asymmetry growth. The role of sphaleron transitions decreasing the left lepton number turns out to be negligible in given scenario. The hypermagnetic helicity plays a key role in lepto/baryogenesis in our scenario and the more hypermagnetic field is close to the maximum helical one the faster BAU grows up the observable value , $B_{obs}\sim 10^{-10}$.

   hep-phastro-ph.COPRD(2016)·25 citations
10. 10*

    Study of HERA ep Data at Low Q^2 and Low x_Bj and the Need for Higher-Twist Corrections to Standard pQCD Fits

    I. Abt🇩🇪 · A.M. Cooper-Sarkar🇬🇧 · B.Foster🇬🇧 · V. Myronenko🇩🇪 · K. Wichmann🇩🇪 · M. Wing🇬🇧

    A detailed comparison of HERA data at low Bjorken-$x$ and low four-momentum-transfer squared, $Q^2$, with predictions based on $\ln Q^2$ evolution (DGLAP) in perturbative Quantum Chromo Dynamics suggests inadequacies of this framework. The standard DGLAP evolution was augmented by including an additional higher-twist term in the description of the longitudinal structure function, $F_{\mathrm{L}}$. This additional term, $F_{\mathrm{L}}{A}_{\mathrm{L}}^{\mathrm{HT}}/Q^2$, improves the description of the reduced cross sections significantly. The resulting predictions for $F_{\mathrm{L}}$ suggest that further corrections are required for $Q^2$ less than about 2 GeV${}^2$.

    hep-phhep-exPRD(2016)·51 citations
11. 11*

    Degrees of Freedom of the Quark Gluon Plasma, tested by Heavy Mesons

    H. Berrehrah🇩🇪 · M. Nahrgang🇺🇸 · T. Song🇩🇪 · V. Ozvenchuck🇵🇱 · P.B. Gossiaux🇫🇷 · K. Werner🇫🇷 · E. Bratkovskaya🇩🇪 · J. Aichelin🇫🇷

    Heavy quarks (charm and bottoms) are one of the few probes which are sensitive to the degrees of freedom of a Quark Gluon Plasma (QGP), which cannot be revealed by lattice gauge calculations in equilibrium. Due to the rapid expansion of the QGP energetic heavy quarks do not come to an equilibrium with the QGP. Their energy loss during the propagation through the QGP medium depends strongly on the modelling of the interaction of the heavy quarks with the QGP quarks and gluons, i.e. on the assuption of the degrees of freedom of the plasma. Here we compare the results of different models, the pQCD based Monte-Carlo (MC@sHQ), the Dynamical Quasi Particle Model (DQPM) and the effective mass approach, for the drag force in a thermalized QGP and discuss the sensitivity of heavy quark energy loss on the properties of the QGP as well as on non-equilibrium dynamics

    hep-phnucl-thFIAS Interdisc.Sci.Ser.(2017)·3 citations
12. 12*

    331 Models Facing the Tensions in $\Delta F=2$ Processes with the Impact on ${\epsilon }^{\prime }/\epsilon$, $B_s\to {\mu }^{+}{\mu }^{-}$ and $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$

    Andrzej J. Buras🇩🇪 · Fulvia De Fazio🇮🇹

    Motivated by the recently improved lattice QCD results on the hadronic matrix elements entering $\Delta M_{s,d}$ in $B_{s,d}^0-{\bar{B}}_{s,d}^0$ mixings and the resulting increased tensions between $\Delta M_{s,d}$ and ${\epsilon }_K$ in the Standard Model and CMFV models, we demonstrate that these tensions can be removed in 331 models based on the gauge group $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ both for $M_{Z^{\prime }}$ in the LHC reach and well beyond it. But the implied new physics (NP) patterns in $\Delta F=1$ observables depend sensitively on the value of $|V_{cb}|$. Concentrating the analysis on three 331 models that have been selected by us previously on the basis of their performance in electroweak precision tests and ${\epsilon }^{\prime }/\epsilon$ we illustrate this for $|V_{cb}|=0.042$ and $|V_{cb}|=0.040$. We find that these new lattice data still allow for positive shifts in ${\epsilon }^{\prime }/\epsilon$ up to $6\times 10^{-4}$ for $M_{Z^{\prime }}=3TeV$ for both values of $$|V_{cb}|$ but for $M_{Z^{\prime }}=10TeV$ only for $|V_{cb}|=0.040$ such shifts can be obtained. NP effects in $B_s\to {\mu }^{+}{\mu }^{-}$ and in the Wilson coefficient $C_9$ are significantly larger in all three models for the case of $|V_{cb}|=0.040$. In particular in two models the rate for $B_s\to {\mu }^{+}{\mu }^{-}$ can be reduced by NP by $20\%$ for $M_{Z^{\prime }}=3TeV$ resulting in values in the ballpark of central values from CMS and LHCb. In the third model a shift in $C_9$ up to $C_9^{\text{NP}}=-0.5$ is possible. We also consider the simplest 331 model, analyzed recently in the literature, in which $X=Y$, the usual hypercharge. We find that in this model NP effects in flavour observables are much smaller than in the three models with $X\ne Y$, in particular NP contributions to the ratio ${\epsilon }^{\prime }/\epsilon$ are very strongly suppressed.

    hep-phhep-exhep-latJHEP(2016)·95 citations
13. 13*

    Intercommutation of U(1) global cosmic strings

    Guy D. Moore🇩🇪

    Global strings (those which couple to Goldstone modes) may play a role in cosmology. In particular, if the QCD axion exists, axionic strings may control the efficiency of axionic dark matter abundance. The string network dynamics depend on the string intercommutation efficiency (whether strings re-connect when they cross). We point out that the velocity and angle in a collision between global strings "renormalize" between the network scale and the microscopic scale, and that this plays a significant role in their intercommutation dynamics. We also point out a subtlety in treating intercommutation of very nearly antiparallel strings numerically. We find that the global strings of a O(2)-breaking scalar theory do intercommute for all physically relevant angles and velocities.

    hep-phastro-ph.CO8 citations
14. 14*

    The decays $h^0\to b\bar{b}$ and $h^0\to c\bar{c}$ in the light of the MSSM with quark flavour violation

    H. Eberl🇦🇹 · E. Ginina🇦🇹 · A. Bartl🇦🇹 · K. Hidaka🇯🇵 · W. Majerotto🇦🇹

    We calculate the decay width of h0 -> b bbar in the Minimal Supersymmetric Standard Model (MSSM) with quark flavour violation (QFV) at full one-loop level. We study the effect of scharm-stop mixing and sstrange-sbottom mixing taking into account the constraints from the B meson data. We discuss and compare in detail the decays h0 -> c cbar and h0 -> b bbar within the framework of the perturbative mass insertion technique using the Flavour Expansion Theorem. The deviation of both decay widths from the Standard Model values can be quite large. Whereas in h0 -> c cbar it is almost entirely due to the flavour violating part of the MSSM, in h0 -> b bbar it is mainly due to the flavour conserving part. Nevertheless, the QFV contribution to Gamma(h0 -> b bbar) due to scharm-stop mixing and chargino exchange can go up to about 8%.

    hep-phJHEP(2016)·11 citations
15. 15*

    Vacuum energy, Standard Model physics and the $750\mathrm{GeV}$ Diphoton Excess at the LHC

    Alexander Y. Kamenshchik🇮🇹 · Alexei A. Starobinsky🇷🇺 · Alessandro Tronconi🇮🇹 · Gian Paolo Vacca🇮🇹 · Giovanni Venturi🇮🇹

    The conditions for the cancellation of one loop contributions to vacuum energy (both U.V. divergent and finite) coming from the known (Standard Model) fields and the field associated with the hypothetical 750 Gev diphoton excess are examined. Depending on the nature of this latter resonance we find that in order to satisfy the constraints (sum rules) different additional, minimal field contributions are required, leading to yet to be observed particles.

    hep-phhep-th11 citations
16. 16*

    Leptogenesis via the 750 GeV pseudoscalar

    Alexander Kusenko🇯🇵 · Lauren Pearce🇺🇸 · Louis Yang🇺🇸

    Recently the ATLAS and CMS collaborations have reported evidence of a diphoton excess which may be interpreted as a pseudoscalar boson S with a mass around 750 GeV. To explain the diphoton excess, such a boson is coupled to the Standard Model gauge fields via SFF-dual operators. In this work, we consider the implications of this state for early universe cosmology; in particular, the S field can acquire a large vacuum expectation value due to quantum fluctuations during inflation. During reheating, it then relaxes to its equilibrium value, during which time the same operators introduced to explain the diphoton excess induce a nonzero chemical potential for baryon and lepton number. Interactions such as those involving right-handed neutrinos allow the system to develop a non-zero lepton number, and therefore, this state may also be responsible for the observed cosmological matter-antimatter asymmetry.

    hep-phastro-ph.COPRD(2016)·12 citations
17. 17*

    Search for a narrow baryonic state decaying to $p{K}_S^0$ and $\bar{p}{K}_S^0$ in deep inelastic scattering at HERA

    ZEUS Collaboration: H. Abramowicz · I. Abt · L. Adamczyk · M. Adamus · S. Antonelli · V. Aushev · O. Behnke · U. Behrens · A. Bertolin · S. Bhadra · I. Bloch · E.G. Boos and 114 other authors

    A search for a narrow baryonic state in the $p{K}_S^0$ and $\bar{p}{K}_S^0$ system has been performed in $ep$ collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb${}^{-1}$ taken in 2003-2007. The search was performed with deep inelastic scattering events at an $ep$ centre-of-mass energy of 318 GeV for exchanged photon virtuality, $Q^2$, between 20 and 100 $\mathrm{Ge}{\mathrm{V}}^2$. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb${}^{-1}$ taken in 1996-2000, no resonance peak was found in the $p(\bar{p})K_S^0$ invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.

    ↳ hep-exhep-phPLB(2016)·9 citations
18. 18*

    Effect of GRB spectra on the empirical luminosity correlations and the GRB Hubble diagram

    Hai-Nan Lin🇨🇳 · Xin Li🇨🇳 · Zhe Chang🇨🇳

    The spectra of gamma-ray bursts (GRBs) in a wide energy range can usually be well described by the Band function, which is a two smoothly jointed power laws cutting at a breaking energy. Below the breaking energy, the Band function reduces to a cut-off power law, while above the breaking energy it is a simple power law. However, for some detectors (such as the Swift-BAT) whose working energy is well below or just near the breaking energy, the observed spectra can be fitted to cut-off power law with enough precision. Besides, since the energy band of Swift-BAT is very narrow, the spectra of most GRBs can be fitted well even using a simple power law. In this paper, with the most up-to-date sample of Swift-BAT GRBs, we study the effect of different spectral models on the empirical luminosity correlations, and further investigate the effect on the reconstruction of GRB Hubble diagram. We mainly focus on two luminosity correlations, i.e., the Amati relation and Yonetoku relation. We calculate these two luminosity correlations on both the case that the GRB spectra are modeled by Band function and cut-off power law. It is found that both luminosity correlations only moderately depend on the choice of GRB spectra. Monte Carlo simulations show that Amati relation is insensitive to the high-energy power-law index of the Band function. As a result, the GRB Hubble diagram calibrated using luminosity correlations is almost independent on the GRB spectra.

    ↳ astro-ph.HEastro-ph.COhep-phMNRAS(2016)·9 citations
19. 19*

    Observational Constraints on Decoupled Hidden Sectors

    Matti Heikinheimo🇫🇮 · Tommi Tenkanen🇫🇮 · Kimmo Tuominen🇫🇮 · Ville Vaskonen🇫🇮

    We consider an extension of the Standard Model with a singlet sector consisting of a real (pseudo)scalar and a Dirac fermion coupled with the Standard Model only via the scalar portal. We assume that the portal coupling is weak enough for the singlet sector not to thermalize with the Standard Model allowing the production of singlet particles via the freeze-in mechanism. If the singlet sector interacts with itself sufficiently strongly, it may thermalize within itself, resulting in dark matter abundance determined by the freeze-out mechanism operating within the singlet sector. We investigate this scenario in detail. In particular, we show that requiring the absence of inflationary isocurvature fluctuations provides lower bounds on the magnitude of the dark sector self-interactions and in parts of the parameter space favors sufficiently large self-couplings, supported also by the features observed in the small-scale structure formation.

    ↳ astro-ph.COhep-phPRD(2016)·93 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.