Tue·Nov 3, 2015Tuesday·November 3, 2015

1. 01*

   Nonequilibrium meson production in strong fields

   L. Juchnowski🇵🇱 · D. Blaschke🇷🇺 · T. Fischer🇵🇱 · S. A. Smolyansky🇷🇺

   We develop a kinetic equation approach to nonequilibrium pion and sigma meson production in a time-dependent, chiral symmetry breaking field (inertial mechanism). We investigate the question to what extent the low-momentum pion enhancement observed in heavy-ion collisions at CERN - LHC can be addressed within this formalism. In a first step, we consider the inertial mechanism for nonequilibrium production of $\sigma -$mesons and their simultaneous decay into pion pairs for two cases of $\sigma$ mass evolution. The resulting pion distribution shows a strong low-momentum enhancement which can be approximated by a thermal Bose distribution with a chemical potential that appears as a trace of the nonequilibrium process of its production.

   hep-phJ.Phys.Conf.Ser.(2016)·2 citations
2. 02*

   Drell-Yan Production of W/Z at the LHC with Protons and Heavy Nuclei

   D.B. Clark🇺🇸

   Drell-Yan W/Z electroweak boson production at the LHC is an essential standard candle which is used for calibration of beam luminosity and detector properties. In addition to proton-proton collisions, the LHC has measured heavy nuclei lead-lead and proton-lead W/Z production. Inclusion of these data sets in future fits can provide discriminating information of the nuclear modifications present in the Parton Distribution Functions (PDFs). We present an ongoing analysis of W/Z production in lead-lead and proton-lead collisions at the LHC using the \texttt{nCTEQ15} nuclear Parton Distribution Functions (nPDFs) including uncertainties. The cross sections are calculated at NLO with the \texttt{FEWZ\ 2.1} program at 2.76 and 5.02 TeV. We identify promising observables for the observation of the nuclear modifications.

   hep-ph1 citation
3. 03*

   Aspects of the Flavour Expansion Theorem

   M. Paraskevas🇬🇷

   The Flavour Expansion Theorem, which has been recently proposed as a more general and elegant algebraic method, for the derivation of the commonly used Mass Insertion Approximation, is revisited. The theorem is reviewed, with respect to its straightforward applications in Flavour physics, and compared against the standard diagrammatic flavour basis techniques, in cases where the latter become inadequate.

   hep-phPoS(2015)·1 citation
4. 04*

   Resonances at the LHC beyond the Higgs: The Scalar/Tensor Case

   W. Kilian🇩🇪 · T. Ohl🇩🇪 · J. Reuter🇩🇪 · M. Sekulla🇩🇪

   We study in a bottom-up approach the theoretically consistent description of additional resonances in the electroweak sector beyond the discovered Higgs boson as simplified models. We focus on scalar and tensor resonances. Our formalism is suited for strongly coupled models, but can also be applied to weakly interacting theories. The spurious degrees of freedom of tensor resonances that would lead to bad high-energy behavior are treated using a generalization of the Stuckelberg formalism. We calculate scattering amplitudes for vector-boson and Higgs boson pairs. The high-energy region is regulated by the T-matrix unitarization procedure, leading to amplitudes that are well behaved on the whole phase space. We present numerical results for complete partonic processes that involve resonant vector-boson scattering, for the current and upcoming runs of LHC.

   hep-phhep-exPRD(2016)·43 citations
5. 05*

   Large-$N$ pion scattering at finite temperature: the $f_0(500)$ and chiral restoration

   Santiago Cortes🇨🇴 · Angel Gomez Nicola🇪🇸 · John Morales🇨🇴

   We consider the $O(N+1)/O(N)$ Non-Linear Sigma Model for large $N$ as an effective theory for low-energy QCD at finite temperature $T$, in the chiral limit. At $T=0$ this formulation provides a good description of scattering data in the scalar channel and generates dynamically the $f_0(500)$ pole, the pole position lying within experimental determinations. Previous $T=0$ results with this model are updated using newer analysis of pion scattering data. We calculate the pion scattering amplitude at finite $T$ and show that it satisfies exactly thermal unitarity, which had been assumed but not formally proven in previous works. We discuss the main differences with the $T=0$ result and we show that one can define a proper renormalization scheme with $T=0$ counterterms such that the renormalized amplitude can be chosen to depend only on a few parameters. Next, we analyze the behaviour of the $f_0(500)$ pole at finite $T$, which is consistent with chiral symmetry restoration when the scalar susceptibility is saturated by the $f_0(500)$ state, in a second-order transition scenario and in accordance with lattice and theoretical analysis.

   hep-phPRD(2016)·9 citations
6. 06*

   Realizing the relaxion from multiple axions and its UV completion with high scale supersymmetry

   Kiwoon Choi🇰🇷 · Sang Hui Im🇰🇷

   We discuss a scheme to implement the relaxion solution to the hierarchy problem with multiple axions, and present a UV-completed model realizing the scheme. All of the $N$ axions in our model are periodic with a similar decay constant $f$ well below the Planck scale. In the limit $N\gg 1$, the relaxion $\varphi$ corresponds to an exponentially long multi-helical flat direction which is shaped by a series of mass mixing between nearby axions in the compact field space of $N$ axions. With the length of flat direction given by $\Delta \varphi =2\pi f_{\mathrm{eff}}\sim e^{\xi N}f$ for $\xi =\mathcal{O}(1)$, both the scalar potential driving the evolution of $\varphi$ during the inflationary epoch and the $\varphi$-dependent Higgs boson mass vary with an exponentially large periodicity of $\mathcal{O}(f_{\mathrm{eff}})$, while the back reaction potential stabilizing the relaxion has a periodicity of $\mathcal{O}(f)$. A natural UV completion of our scheme can be found in high scale or (mini) split supersymmetry (SUSY) scenario with the axion scales generated by SUSY breaking as $f\sim \sqrt{m_{\mathrm{SUSY}}{M}_{\ast }}$, where the soft SUSY breaking scalar mass $m_{\mathrm{SUSY}}$ can be well above the weak scale, and the fundamental scale $M_{\ast }$ can be identified as the Planck scale or the GUT scale.

   hep-phhep-thJHEP(2016)·315 citations
7. 07*

   (O_8, O_8) contribution to $\bar{B}\to X_s\gamma \gamma$ at O(\alpha_s)

   H. M. Asatrian🇦🇲 · C. Greub🇨🇭 · A. Kokulu🇬🇧

   In this analysis, we present the contribution associated with the chromomagnetic dipole operator O_8 to the double differential decay width d\Gamma/(ds_1 ds_2) for the inclusive process $\bar{B}\to X_s\gamma \gamma$. The kinematical variables s_1 and s_2 are defined as s_i=(p_b - q_i)^2/m_b^2, where p_b, q_1, q_2 are the momenta of b-quark and two photons. This contribution (taken at tree level) is of order \alpha_s, like the recently calculated QCD corrections to the contribution of the operator O_7. In order to regulate possible collinear singularities of one of the photons with the strange quark, we introduce a non zero mass m_s for the strange quark. Our results are obtained for exact m_s, which we interpret as a constituent mass being varied between 400 and 600 MeV. Numerically it turns out that the effect of the (O_8, O_8) contribution to the branching ratio of $\bar{B}\to X_s\gamma \gamma$ does not exceed +0.1 % for any kinematically allowed value of our physical cutoff parameter c, confirming the expected suppression of this contribution relative to the QCD corrections to d\Gamma_{77}/(ds_1 ds_2).

   hep-phhep-exPRD(2016)·3 citations
8. 08*

   Constraints on top quark flavor changing neutral currents using diphoton events at the LHC

   Sara Khatibi🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

   In this paper we show that the diphoton mass spectrum in proton-proton collisions at the LHC is sensitive to the top quark flavor changing neutral current in the vertices of $tu\gamma$ and $tc\gamma$. The diphoton mass spectrum measured by the CMS experiment at the LHC at a center-of-mass energy of 8 TeV and an integrated luminosity of 19.5 fb${}^{-1}$ is used as an example to set limits on these FCNC couplings. It is also shown that the angular distribution of the diphotons is sensitive to anomalous $tu\gamma$ and $tc\gamma$ couplings and it is a powerful tool to probe any value of the branching fraction of top quark rare decay to an up-type quark plus a photon down to the order of $10^{-4}$. We also show that the $tu\gamma$ FCNC coupling has a significant contribution to the neutron electric dipole moment (EDM) and the upper bound on neutron EDM can be used to constrain the $tu\gamma$ FCNC coupling.

   hep-phNPB(2016)·22 citations
9. 09*

   A Kinematic Condition on Intrinsic Charm

   Johannes Blümlein🇩🇪

   We derive a kinematic condition on the resolution of intrinsic charm and discuss phenomenological consequences.

   hep-phhep-exPLB(2016)·37 citations
10. 10*

    Generalized thermalization time of dark matter captured by neutron stars

    Yusuke Sanematsu🇯🇵 · Motoi Tachibana🇯🇵

    We discuss the issue on dark matter capture by neutron stars, in particular the process of dark matter thermalization, by which the scattering cross section and the mass of dark matter can be constrained. At first, we evaluate the thermalization time of self-interacting dark matter and find the effect of the self-interaction is small compared with that of the interaction with nucleons. Then we generalize the thermalization time by introducing a set of new parameters. We show how the cross section is affected by those new parameters. It turns out that the cross section gets very sensitive to and strongly constrained by one of the new parameters.

    hep-phastro-ph.HEastro-ph.SR1 citation
11. 11*

    Predicted Higgs-related spin 1/2 particles as a new dark matter candidate

    Joshua Stenzel🇺🇸 · Johannes Kroll🇨🇿 · Minjie Lei🇺🇸 · Roland E. Allen🇺🇸

    The theory at arXiv:1101.0586 [hep-th] predicts new fundamental spin $1/2$ particles which can be produced in pairs through their couplings to vector bosons or fermions. The lowest-energy of these should have a mass $m_{1/2}$ comparable to the mass $m_h$ of the recently discovered Higgs boson, with $m_{1/2}=m_h$ in the simplest model. These particles should therefore be detectable in collider experiments, perhaps in Run 2 or 3 of the LHC. They cannot decay through any obvious mechanisms in standard physics, making them a new dark matter candidate. In the simplest model, annihilations would produce a well-defined signature with photons, positrons, and excess electrons at about 125 GeV, and the mass would also be well-defined for direct dark matter detection.

    hep-ph0 citations
12. 12*

    Pion and kaon in the Beth-Uhlenbeck approach

    A. Dubinin🇵🇱 · D. Blaschke🇷🇺 · A. Radzhabov🇷🇺

    In the present work the Mott effect for pions and kaons is described within a Beth- Uhlenbeck approach on the basis of the PNJL model. The contribution of these degrees of freedom to the thermodynamics is encoded in the temperature dependence of their phase shifts. A comparison with results from $N_f=2+1$ lattice QCD thermodynamics is performed.

    hep-phnucl-thJ.Phys.Conf.Ser.(2016)·3 citations
13. 13*

    A class of Z' models with non-universal couplings and protected flavor-changing interactions

    Javier Fuentes-Martin🇪🇸

    Motivated by the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies recently reported by the LHCb collaboration, I present a class of flavored U(1)' gauge extensions of the Standard Model that naturally accommodates them and possesses a rich phenomenology. This model is characterized by the presence of tree-level flavor-changing interactions in the down-quark sector, protected by off-diagonal quark-mixing matrix elements. Anomaly cancellation fixes the extension of the symmetry to the lepton sector in a very specific way, giving rise to flavor-conserving family-non-universal Z' couplings. The fermion content of this model is the same as in the SM while the scalar sector is extended with an extra Higgs doublet and a scalar singlet. The model will be tested in the next run of LHC and presents specific correlations in certain flavor observables that allow to clearly discriminate among them and from other new physics signals.

    hep-phPoS(2015)·1 citation
14. 14*

    Precision QCD for LHC Physics: The nCTEQ15 PDFs

    Fredrick I. Olness🇺🇸

    Searches for new physics at the LHC will increasingly depend on identifying deviations from precision Standard Model (SM) predictions. At the higher energy scales involved for the LHC Run 2, the heavy quarks play a more prominent role than at the Tevatron. Recent theoretical developments improve our ability to address multi-scale problems and properly incorporate heavy quark masses across the full kinematic range. These developments are incorporated into the new nCTEQ15 PDFs, and we review these developments with respect to sample Run 2 measurements, and identify areas where additional effort is required.

    hep-ph0 citations
15. 15*

    Saturation Physics on the Energy Frontier

    David Zaslavsky

    Saturation physics is expected to be relevant at sufficiently small parton momentum fractions $x$ in high-energy proton- (or deuteron-)ion collisions at RHIC and the LHC. Accordingly, these collisions provide the best available testing ground for the saturation model. However, producing precise numerical predictions from the model is a complicated task; the state of the art in this area involves next-to-leading order QCD calculations, which are difficult to do numerically. Here I'll review recent progress in extracting numerical predictions from saturation models and matching them to experimental results.

    hep-ph1 citation
16. 16*

    Exploration of Beyond the Standard Model Physics at the ILC

    Stefania Gori🇨🇦

    The International Linear Collider (ILC) will advance our understanding of fundamental physics, through a program for precision measurements of the Higgs boson and of the top quark properties. An additional crucial goal of the ILC will be the direct discovery of light New Physics (NP) particles. This proceeding gives an overview of the ILC direct discovery potential. Special emphasis is dedicated to the discovery prospects for light hidden Supersymmetric particles, such as Higgsinos and staus. Furthermore, it will be extremely promising to have analyses aimed to the discovery of light hidden NP particles produced from new decay modes of the Higgs boson. The ILC low background environment, as well as the precise knowledge of the initial-state beams are also ideal for the precise measurements of the spectrum and interactions of these NP particles, once discovered.

    hep-ph1 citation
17. 17*

    One-loop corrections to the Higgs electroweak chiral Lagrangian

    Feng-Kun Guo🇨🇳 · Pedro Ruiz-Femenia🇩🇪 · Juan Jose Sanz-Cillero

    In this talk we study beyond Standard Model scenarios where the Higgs is non-linearly realized. The one-loop ultraviolet divergences of the low-energy effective theory at next-to-leading order, O(p^4), are computed by means of the background-field method and the heat-kernel expansion. The power counting in non-linear theories shows that these divergences are determined by the leading-order effective Lagrangian L_2. We focus our attention on the most important O(p^4) divergences, which are provided by the loops of Higgs and electroweak Goldstones, as these particle are the only ones that couple through derivatives in L_2. The one-loop divergences are renormalized by O(p^4) effective operators, and set their running. This implies the presence of chiral logarithms in the amplitudes along with the O(p^4) low-energy couplings, which are of a similar importance and should not be neglected in next-to-leading order effective theory calculations, e.g. in composite scenarios.

    hep-phPoS(2015)·0 citations
18. 18*

    Leptonic Unitarity Triangles and Effective Mass Triangles of the Majorana Neutrinos

    Zhi-zhong Xing🇨🇳 · Jing-yu Zhu🇨🇳

    Given the best-fit results of six neutrino oscillation parameters, we plot the Dirac and Majorana unitarity triangles (UTs) of the 3\times 3 lepton flavor mixing matrix to show their real shapes for the first time. The connections of the Majorana UTs with neutrino-antineutrino oscillations and neutrino decays are explored, and the possibilities of right or isosceles UTs are discussed. In the neutrino mass limit of m_1 \to 0 or m_3 \to 0, which is allowed by current experimental data, we show how the six triangles formed by the effective Majorana neutrino masses \langle m\rangle_{\alpha\beta} (for \alpha, \beta = e, \mu, \tau) and their corresponding component vectors look like in the complex plane. The relations of such triangles to the Majorana phases and to the lepton-number-violating decays H^{++} \to \alpha^+ \beta^+ in the type-II seesaw mechanism are also illustrated.

    hep-phhep-exNPB(2016)·18 citations
19. 19*

    Probing the gluon density of the proton in the exclusive photoproduction of vector mesons at the LHC: A phenomenological analysis

    V. P. Goncalves🇧🇷 · L. A. S. Martins🇧🇷 · W. K. Sauter🇧🇷

    The current uncertainty on the gluon density extracted from the global parton analysis is large in the kinematical range of small values of the Bjorken - $x$ variable and low values of the hard scale $Q^2$. An alternative to reduces this uncertainty is the analysis of the exclusive vector meson photoproduction in photon - hadron and hadron - hadron collisions. This process offers a unique opportunity to constrain the gluon density of the proton, since its cross section is proportional to the gluon density squared. In this paper we consider current parametrizations for the gluon distribution and estimate the exclusive vector meson photoproduction cross section at HERA and LHC using the leading logarithmic formalism. We perform a fit of the normalization of the $\gamma h$ cross section and the value of the hard scale for the process and demonstrate that the current LHCb experimental data are better described by models that assume a slow increasing of the gluon distribution at small - $x$ and low $Q^2$.

    hep-phhep-exEPJC(2016)·14 citations
20. 20*

    On the $\pi \pi$-scattering lengths in the theory with effective Lagrangian

    E. P. Shabalin🇷🇺

    Use of the effective Lagrangian incorporating both the scalar and pseudoscalar mesons gives a possibility to calculate the $\pi \pi$-scattering lengths without attraction of the ChPT theory.

    hep-phPhys.Atom.Nucl.(2016)·0 citations
21. 21*

    Gauge-Invariant Gluon TMD and Evolution in the Coordinate Space

    I.O. Cherednikov🇧🇪

    Maximally path-dependent gauge-invariant operator definition of the gluon transverse-momentum dependent pdf (gTMD) is discussed. It is argued that the evolution equations for the gTMD in the coordinate representation can be derived from the equations of motion in the generalised loop space, whose elements are the hadronic averages of the Wilson loops of entirely arbitrary shape.

    hep-phhep-latnucl-thPoS(2015)·2 citations
22. 22*

    High-precision differential predictions for top-quark pairs at the LHC

    Michal Czakon🇩🇪 · David Heymes🇬🇧 · Alexander Mitov🇬🇧

    We present the first complete next-to-next-to-leading order (NNLO) QCD predictions for differential distributions in the top-quark pair production process at the LHC. Our results are derived from a fully differential partonic Monte Carlo calculation with stable top quarks which involves no approximations beyond the fixed-order truncation of the perturbation series. The NNLO corrections improve the agreement between existing LHC measurements [V. Khachatryan et al. (CMS Collaboration), Eur. Phys. J. C 75, 542 (2015)] and standard model predictions for the top-quark transverse momentum distribution, thus helping alleviate one long-standing discrepancy. The shape of the top-quark pair invariant mass distribution turns out to be stable with respect to radiative corrections beyond NLO which increases the value of this observable as a place to search for physics beyond the standard model. The results presented here provide essential input for parton distribution function fits, implementation of higher-order effects in Monte Carlo generators as well as top-quark mass and strong coupling determination.

    hep-phhep-exPRL(2016)·397 citations
23. 23*

    Baryogenesis in the Zee-Babu model with arbitrary $\xi$ gauge

    Vo Quoc Phong🇻🇳 · Nguyen Chi Thao🇻🇳 · Hoang Ngoc Long🇻🇳

    We consider the baryogenesis picture in the Zee-Babu model. Our analysis shows that electroweak phase transition (EWPT) in the model is a first-order phase transition at the $100$ GeV scale, its strength ranges from 1 to 4.15 and the masses of charged Higgs boson are smaller than $300$ GeV. The EWPT is strengthened by only the new bosons and this strength is enhanced by arbitrary $\xi$ gauge. However, the $\xi$ gauge does not break the first-order EWPT or, in other words, the $\xi$ gauge is not the cause of the EWPT. This leads to the fact that the calculation of EWPT in Landau gauge is enough; and the latter may provide baryon-number violation (B-violation) necessary for baryogenesis in the relationship with nonequilibrium physics in the early universe.

    hep-phPRD(2018)·10 citations
24. 24*

    Dispersion Relations for Electroweak Observables in Composite Higgs Models

    Roberto Contino🇨🇭 · Matteo Salvarezza🇮🇹

    We derive dispersion relations for the electroweak oblique observables measured at LEP in the context of $SO(5)/SO(4)$ composite Higgs models. It is shown how these relations can be used and must be modified when modeling the spectral functions through a low-energy effective description of the strong dynamics. The dispersion relation for the parameter ${ϵ}_3$ is then used to estimate the contribution from spin-1 resonances at the 1-loop level. Finally, it is shown that the sign of the contribution to the $\hat{S}$ parameter from the lowest-lying spin-1 states is not necessarily positive definite, but depends on the energy scale at which the asymptotic behavior of current correlators is attained.

    hep-phPRD(2015)·10 citations
25. 25*

    Lorentz and CPT Violation in Top-Quark Production

    Zhi Liu🇺🇸

    Signals for Lorentz and CPT violation can appear in a wide range of experiments including hadron colliders like the LHC. We present a calculation of the Lorentz-violating cross section for top-quark pair production via gluon fusion. This process dominates at the LHC, and analysis of LHC data should permit sharpening the constraints on top-quark Lorentz violation obtained recently by the D0 Collaboration. We also present a separate calculation of single-top production, which is sensitive to CPT violation. Data from the LHC can be used to measure coefficients for CPT violation in the top-quark sector for the first time.

    hep-ph0 citations
26. 26*

    Chiral Magnetic-Vortical Wave

    David Frenklakh🇷🇺

    We study collective excitations in rotating chiral media in presence of magnetic field both in hydrodynamic framework and in kinetic theory. We find that the velocity of the mixed Chiral Magnetic-Vortical Wave is a vector sum of velocities of pure Magnetic and Vortical waves which do not exist separately under these conditions. We also use relaxation time approximation to prove that this wave itself is a non-dissipative phenomenon.

    ↳ hep-thhep-ph4 citations
27. 27*

    Search for Gamma-Ray Lines towards Galaxy Clusters with the Fermi-LAT

    B. Anderson🇸🇪 · S. Zimmer🇸🇪 · J. Conrad🇸🇪 · M. Gustafsson🇩🇪 · M. Sánchez-Conde🇸🇪 · R. Caputo🇺🇸

    We report on a search for monochromatic $\gamma$-ray features in the spectra of galaxy clusters observed by the \emph{Fermi} Large Area Telescope. Galaxy clusters are the largest structures in the Universe that are bound by dark matter (DM), making them an important testing ground for possible self-interactions or decays of the DM particles. Monochromatic $\gamma$-ray lines provide a unique signature due to the absence of astrophysical backgrounds and are as such considered a smoking-gun signature for new physics. An unbinned joint likelihood analysis of the sixteen most promising clusters using five years of data at energies between 10 and 400 GeV revealed no significant features. For the case of self-annihilation, we set upper limits on the monochromatic velocity-averaged interaction cross section. These limits are compatible with those obtained from observations of the Galactic Center, albeit weaker due to the larger distance to the studied clusters.

    ↳ astro-ph.HEhep-phJCAP(2016)·57 citations
28. 28*

    Designing and testing inflationary models with Bayesian networks

    Layne C. Price🇺🇸 · Hiranya V. Peiris🇬🇧 · Jonathan Frazer🇩🇪 · Richard Easther🇳🇿

    Even simple inflationary scenarios have many free parameters. Beyond the variables appearing in the inflationary action, these include dynamical initial conditions, the number of fields, and couplings to other sectors. These quantities are often ignored but cosmological observables can depend on the unknown parameters. We use Bayesian networks to account for a large set of inflationary parameters, deriving generative models for the primordial spectra that are conditioned on a hierarchical set of prior probabilities describing the initial conditions, reheating physics, and other free parameters. We use $N_f$--quadratic inflation as an illustrative example, finding that the number of $e$-folds $N_{\ast }$ between horizon exit for the pivot scale and the end of inflation is typically the most important parameter, even when the number of fields, their masses and initial conditions are unknown, along with possible conditional dependencies between these parameters.

    ↳ astro-ph.COhep-phhep-thJCAP(2016)·21 citations
29. 29*

    Observables of non-equilibrium phase transition

    Boris Tomasik🇸🇰 · Martin Schulc🇨🇿 · Ivan Melo🇸🇰 · Renata Kopecna🇨🇿

    A rapidly expanding fireball which undergoes first-order phase transition will supercool and proceed via spinodal decomposition. Hadrons are produced from the individual fragments as well as the left-over matter filling the space between them. Emission from fragments should be visible in rapidity correlations, particularly of protons. In addition to that, even within narrow centrality classes, rapidity distributions will be fluctuating from one event to another in case of fragmentation. This can be identified with the help of Kolmogorov-Smirnov test. Finally, we present a method which allows to sort events with varying rapidity distributions in such a way, that events with similar rapidity histograms are grouped together.

    ↳ nucl-thhep-exhep-phEPJA(2016)·1 citation
30. 30*

    Hypermagnetic gyrotropy, inflation and the baryon asymmetry of the Universe

    Massimo Giovannini🇨🇭

    We investigate the production of the hypermagnetic gyrotropy when the electric and magnetic gauge couplings evolve at different rates, as it happens in the the relativistic theory of the Van der Waals forces. If a pseudo-scalar interaction breaks the duality symmetry of the corresponding equations, the gyrotropic configurations of the hypermagnetic fields can be amplified from the vacuum during an inflationary stage of expansion. After charting the parameter space of the model in terms of the rates of evolution of the magnetic and electric gauge couplings, we identify the regions where the gyrotropy is sufficiently intense to seed the baryon asymmetry of the Universe at the electroweak epoch while the backreaction constraints, the strong coupling bounds and the other astrophysical limits are concurrently satisfied.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2015)·13 citations
31. 31*

    Search for Flavor Changing Non-standard Interactions with the MINOS+ Experiment

    Nick Graf🇺🇸

    A study of MINOS+ sensitivity to non-standard interactions and previously published results using MINOS data are presented.

    ↳ hep-exhep-ph3 citations
32. 32*

    Quark stars admixed with dark matter

    Payel Mukhopadhyay🇮🇳 · Juregen Schaffner-Bielich🇩🇪

    Compact stars consisting of massless quark matter and fermionic dark matter are studied by solving the Tolman-Oppenheimer-Volkoff equations for two fluids separately. Dark matter is further investigated by incorporating inter-fermionic interactions among the dark matter particles. The properties of stars made of quark matter particles and self-interacting and free dark matter particles are explored by obtaining their mass-radius relations. The regions of stability for such a compact star are determined and it is demonstrated that the maximum stable total mass of such a star decreases approximately linearly with increasing dark matter fraction.

    ↳ astro-ph.HEhep-phPRD(2016)·104 citations
33. 33*

    Light-quark baryon spectroscopy from ANL-Osaka dynamical coupled-channels analysis

    Hiroyuki Kamano🇯🇵

    We review our recent efforts for determining resonance parameters associated with light-quark baryons ($N^{\ast }$, ${\Delta }^{\ast }$, ${\Lambda }^{\ast }$, ${\Sigma }^{\ast }$) through comprehensive analyses of various meson production reactions off the nucleon within the ANL-Osaka dynamical coupled-channels approach.

    ↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2016)·1 citation
34. 34*

    Generalisation of the Yang-Mills Theory

    George Savvidy🇬🇷

    We suggest an extension of the gauge principle which includes tensor gauge fields. In this extension of the Yang-Mills theory the vector gauge boson becomes a member of a bigger family of gauge bosons of arbitrary large integer spins. The proposed extension is essentially based on the extension of the Poincaré algebra and the existence of an appropriate transversal representations. The invariant Lagrangian is expressed in terms of new higher-rank field strength tensors. It does not contain higher derivatives of tensor gauge fields and all interactions take place through three- and four-particle exchanges with a dimensionless coupling constant. We calculated the scattering amplitudes of non-Abelian tensor gauge bosons at tree level, as well as their one-loop contribution into the Callan-Symanzik beta function. This contribution is negative and corresponds to the asymptotically free theory. Considering the contribution of tensorgluons of all spins into the beta function we found that it is leading to the theory which is conformally invariant at very high energies. The proposed extension may lead to a natural inclusion of the standard theory of fundamental forces into a larger theory in which vector gauge bosons, leptons and quarks represent a low-spin subgroup. We consider a possibility that inside the proton and, more generally, inside hadrons there are additional partons - tensorgluons, which can carry a part of the proton momentum. The extension of QCD influences the unification scale at which the coupling constants of the Standard Model merge, shifting its value to lower energies.

    ↳ hep-thhep-phInt.J.Mod.Phys.A(2016)·6 citations
35. 35*

    Search for a light dark sector particle at LHCb

    Andrea Mauri🇨🇭

    A search is presented for a hidden-sector boson, $\chi$, produced in the decay $B^0\to K^{\ast }(892{)}^0\chi$, with $K^{\ast }(892{)}^0\to K^{+}{\pi }^{-}$ and $\chi \to {\mu }^{+}{\mu }^{-}$ . The search is performed using a $pp$-collision data sample collected at $\sqrt{s}=7$ and 8 TeV with the LHCb detector, corresponding to integrated luminosities of 1 and 2 fb${}^{-1}$ respectively. No significant signal is observed in the mass range $214\le m_{\chi }\le 4350$ MeV, and upper limits are placed on the branching fraction product $\mathcal{B}(B^0\to K^{\ast }(892{)}^0\chi )\times \mathcal{B}(\chi \to {\mu }^{+}{\mu }^{-})$ as a function of the mass and lifetime of the $\chi$ boson. These limits place the most stringent constraints to date on many theories that predict the existence of additional low-mass dark bosons.

    ↳ hep-exhep-ph0 citations
36. 36*

    The Higgs Physics Program at the International Linear Collider

    Jan Strube🇺🇸

    The International Linear Collider (ILC) is a proposed electron -- positron collider with a collision energy of $\sqrt{s}$ = 500 GeV in the baseline configuration. The ILC physics program takes full advantage of the fact that the machine can be operated at arbitrary energy from the maximum down to the peak of the ZH production cross section near $\sqrt{s}$ = 250 GeV or below. It will advance our understanding of nature through precision measurements of Standard Model parameters, detailed study of the Higgs sector, and a comprehensive search for new phenomena that extends beyond the purely kinematic reach. This note gives an overview of the ILC Higgs program.

    ↳ hep-exhep-ph2 citations
37. 37*

    Searches for New Physics at the Belle II Experiment

    Boqun Wang🇺🇸

    The Belle II experiment at the SuperKEKB collider is an upgrade of the Belle / KEKB experiment. It will start physics data taking from 2018 and with $40$ times luminosity, its goal is to accumulate 50 $a{b}^{-1}$ of $e^{+}{e}^{-}$ collision data. The physics programs have a wide range of areas for new physics, such as more constraints on CKM Unitarity Triangle, searching for charged Higgs, direct CPV, Lepton Flavour Violation and dark matter.In this monograph, we will review the current status of Belle II and SuperKEKB construction and introduce the main physics opportunities at this facility.

    ↳ hep-exhep-ph7 citations
38. 38*

    Enhanced effects of variation of the fundamental constants in laser interferometers and application to dark matter detection

    Y. V. Stadnik🇦🇺 · V. V. Flambaum🇦🇺

    We outline new laser interferometer measurements to search for variation of the electromagnetic fine-structure constant $\alpha$ and particle masses (including a non-zero photon mass). We propose a strontium optical lattice clock -- silicon single-crystal cavity interferometer as a novel small-scale platform for these new measurements. Multiple passages of a light beam inside an interferometer enhance the effects due to variation of the fundamental constants by the mean number of passages ($N_{\text{eff}}\sim 10^2$ for a large-scale gravitational-wave detector, such as LIGO, Virgo, GEO600 or TAMA300, while $N_{\text{eff}}\sim 10^5$ for a strontium clock -- silicon cavity interferometer). Our proposed laser interferometer measurements may be implemented as an extremely precise tool in the direct detection of scalar dark matter that forms an oscillating classical field or topological defects.

    ↳ physics.atom-phhep-phphysics.ins-detphysics.opticsPRA(2016)·147 citations
39. 39*

    Birth of colliding beams in Europe, two photon studies at Adone

    Luisa Bonolis🇩🇪 · Giulia Pancheri🇮🇹

    This article recalls the birth of the first electron-positron storage ring AdA, and the construction of the higher energy collider ADONE, where early photon-photon collisions were observed. The events which led the Austrian physicist Bruno Touschek to propose and construct AdA will be recalled, starting with early work on the Wideroe's betatron during World War II, up to the construction of ADONE, and the theoretical contribution to radiative corrections to electron-positron collisions.

    ↳ physics.hist-phhep-ph1 citation
40. 40*

    Large N meson propagators from twisted space-time reduced model

    Antonio González-Arroyo🇪🇸 · Masanori Okawa🇯🇵

    Recently, we proposed a new method to calculate meson propagators in the large $N$ limit from twisted space-time reduced model. In this note, we give simulation details for obtaining meson spectra and discuss the smearing technique which should improve the signal of meson propagators in future works.

    ↳ hep-lathep-phhep-thPoS(2016)·4 citations
41. 41*

    Assessing Theory Uncertainties in EFT Power Countings from Residual Cutoff Dependence

    Harald W. Griesshammer (George Washington U.)🇺🇸

    I summarise a method to quantitatively assess the consistency of power-counting proposals in Effective Field Theories which are non-perturbative at leading order. It uses the fact that the Renormalisation Group evolution of an observable predicts the functional form of its residual cutoff dependence on the EFT breakdown scale, low-momentum scales, and the order of the calculation. Passing this test is a necessary but not sufficient consistency criterion for a suggested power counting whose exact nature is disputed. For example, in ChiEFT with more than one nucleon, a lack of universally accepted analytic solutions obfuscates the relation between convergence pattern and numerical results, and led to proposals which predict different numbers of Low Energy Coefficients at the same chiral order. The method may provide an independent check whether an observable is renormalised at a given order, and of both the breakdown scale and the momentum-dependent order-by-order convergence pattern of an EFT. Conversely, it may help identify LECs which produce renormalised observables at a given order. I also discuss its underlying assumptions and relation to the RG Equation; useful choices for observables and cutoffs; the momentum window in which the test provides best signals; its dependence on the values and forms of cutoffs as well as on the EFT parameters; the impact of fitting Low Energy Coefficients to data in different or the same channel; caveats and limitations. Since the test is designed to minimise the use of data, it allows one to quantitatively falsify if the EFT has been renormalised consistently, rather than quantifying how an EFT compares to experiment. Its application in particular to the 3P0 and 3P2-3F2 partial waves of NN scattering in ChiEFT may elucidate persistent power-counting issues. Details and a better bibliography can be found in an upcoming publication.

    ↳ nucl-thhep-phPoS(2016)·20 citations
42. 42*

    On the measurement of Adler angles in charge current single pion neutrino-nucleusinteractions

    F. Sánchez🇪🇸

    The modelling of neutrino nucleus interactions is one of the limiting systematic errors in long base line neutrino oscillation experiments. The accurate modelling of the neutrino interactions requires more experimental observables to determine its accuracy. Adler Angles are observables carrying information about the polarization of the ?{\Delta} resonance and the interference with the non-resonant single pion production. These observables were measured with limited statistics in bubble chamber experiments. We discuss the possibility of measuring the angles in neutrino interactions with nucleus.

    ↳ hep-exhep-phnucl-exPRD(2016)·14 citations
43. 43*

    Primordial ${}^4\text{He}$ constraints on inelastic macro dark matter revisited

    David M. Jacobs🇿🇦 · Gwyneth Allwright🇿🇦 · Mpho Mafune🇿🇦 · Samyukta Manikumar🇿🇦 · Amanda Weltman🇿🇦

    At present, the best model for the evolution of the cosmos requires that dark matter make up approximately $25\%$ of the energy content of the Universe. Most approaches to explain the microscopic nature of dark matter, to date, have assumed its composition to be of intrinsically weakly interacting particles; however, this need not be the case to have consistency with all extant observations. Given decades of inconclusive evidence to support any dark matter candidate, there is strong motivation to consider alternatives to the standard particle scenario. One such example is macro dark matter, a class of candidates (macros) that could interact strongly with the particles of the Standard Model, have large masses and physical sizes, and yet behave as dark matter. Macros that scatter completely inelastically could have altered the primordial production of the elements, and macro charge-dependent constraints have been obtained previously. Here we reconsider the phenomenology of inelastically interacting macros on the abundance of primordially produced ${}^4\text{He}$ and revise previous constraints by also taking into account improved measurements of the primordial ${}^4\text{He}$ abundance. The constraints derived here are limited in applicability to only leptophobic macros that have a surface potential $V\gtrsim 0.5$MeV. However, an important conclusion from our analysis is that even neutral macros would likely affect the abundance of the light elements. Therefore, constraints on that scenario are possible and are currently an open question.

    ↳ astro-ph.COhep-phPRD(2016)·0 citations
44. 44*

    Thermodynamics of Cosmic Defect Network Evolution

    P. P. Avelino🇵🇹 · L. Sousa🇵🇹

    We show that simple thermodynamic conditions determine, to a great extent, the equation of state and dynamics of cosmic defects of arbitrary dimensionality. We use these conditions to provide a more direct derivation of the Velocity-dependent One-Scale (VOS) model for the macroscopic dynamics of topological defects of arbitrary dimensionality in a $N+1$-dimensional homogeneous and isotropic universe. We parameterize the modifications to the VOS model associated to the interaction of the topological defects with other fields, including, in particular, a new dynamical degree of freedom associated to the variation of the mass per unit $p$-area of the defects, and compute the corresponding scaling solutions. The observational impact of this new dynamical degree of freedom is also briefly discussed.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2016)·11 citations
45. 45*

    The general form of the coupled Horndeski Lagrangian that allows cosmological scaling solutions

    Adalto R. Gomes🇧🇷 · Luca Amendola🇩🇪

    We consider the general scalar field Horndeski Lagrangian coupled to matter. Within this class of models, we present two results that are independent of the particular form of the model. First, we show that in a Friedmann-Robertson-Walker metric the Horndeski Lagrangian coincides with the pressure of the scalar field. Second, we employ the previous result to identify the most general form of the Lagrangian that allows for cosmological scaling solutions, i.e. solutions where the ratio of matter to field density and the equation of state remain constant. Scaling solutions of this kind may help solving the coincidence problem since in this case the presently observed ratio of matter to dark energy does not depend on initial conditions, but rather on the theoretical parameters.

    ↳ gr-qcastro-ph.COhep-phJCAP(2016)·20 citations
46. 46*

    TaN, a molecular system for probing $\mathcal{P},\mathcal{T}$-violating hadron physics

    Timo Fleig🇫🇷 · Malaya K. Nayak🇫🇷 · Mikhail Kozlov🇷🇺

    All-electron configuration interaction theory in the framework of the Dirac-Coulomb Hamiltonian has been applied to the TaN molecule, a promising candidate in the search for Beyond-Standard-Model physics in both the hadron and the lepton sector of matter. We obtain in the first excited {${}^3{\Delta }_1$} state a $\mathcal{P},\mathcal{T}$-odd effective electric field of $36.0\left[\frac{\mathrm{GV}}{\mathrm{cm}}\right]$, a scalar-pseudoscalar $\mathcal{P},\mathcal{T}$-odd interaction constant of $32.8$ [kHz], and a nuclear magnetic-quadrupole moment interaction constant of $0.74$ [$\frac{10^{33}\text{Hz}}{e{\text{cm}}^2}$]. The latter interaction constant has been obtained with a new approach which we describe in detail. Using the same highly correlated all-electron wavefunctions with up to $2.5$ billion expansion terms, we obtain a parallel magnetic hyperfine interaction constant of $-2954$ [MHz] for the ${}^{181}\mathrm{T}\mathrm{a}$ nucleus, a very large molecule-frame electric dipole moment of $-4.91$ [Debye], and spectroscopic constants for the four lowest-lying electronic states of the molecule.

    ↳ physics.atom-phhep-phquant-phPRA(2016)·22 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.