Tue·Sep 1, 2015Tuesday·September 1, 2015

1. 01*

   The search for mirror quarks at the LHC

   S. Chakdar🇺🇸 · K. Ghosh🇺🇸 · V. Hoang🇺🇸 · P. Q. Hung🇺🇸 · S. Nandi🇺🇸

   Observation of non-zero neutrino masses at a scale $\sim 10^{-1}-10^{-2}$ eV is a major problem in the otherwise highly successful Standard Model. The most elegant mechanism to explain such tiny neutrino masses is the seesaw mechanism with right handed neutrinos. However, the required seesaw scale is so high, $\sim 10^{14}$ GeV, it will not have any collider implications. Recently, an explicit model has been constructed to realize the seesaw mechanism with the right handed neutrinos at the electroweak scale. The model has a mirror symmetry having both the left and right lepton and quark doublets and singlets for the same $SU(2{)}_W$ gauge symmetry. Additional Higgs multiplets have been introduced to realize this scenario. It turns out that these extra Higgs fields also help to satisfy the precision electroweak tests, and other observables. Because the scale of the symmetry breaking is electroweak, both the mirror quark and mirror leptons have masses in the electroweak scale in the range $\sim 150-800$ GeV. The mirror quarks / leptons decay to ordinary quarks /leptons plus very light neutral scalars. In this work, we calculate the final state signals arising from the pair productions of these mirror quarks and their subsequent decays. We find that these signals are well observable over the Standard Model background for $13$ TeV LHC. Depending on the associated Yukawa couplings, these decays can also give rise displaced vertices with long decay length, very different from the usual displaced vertices associated with b decays.

   hep-phPRD(2016)·19 citations
2. 02*

   Neutral meson mixing induced by box diagrams in the 3-3-1 model with heavy leptons

   F. C. Correia🇧🇷 · V. Pleitez🇧🇷

   We consider in the 3-3-1 model with heavy leptons the box contributions to the mass difference in $K$ and $B$ neutral mesons induced by neutral (pseudo)scalars, exotic charged quarks, singly and doubly charged scalar and gauge bosons. In particular, we include the effects of a real scalar with mass near 125 GeV but with non-diagonal couplings to quarks. We show that, as in the tree level case, there are ranges of the parameters in which these contributions can be enough suppressed by negative interference among several amplitudes. Hence, in this model these $\Delta F=2$ processes may be dominated by the standard model contributions. In addition, our results are valid in the minimal 3-3-1 model without the sextet.

   hep-phPRD(2015)·11 citations
3. 03*

   Energy-dependent dipole form factor in a QCD-inspired model

   C. A. S. Bahia🇧🇷 · M. Broilo🇧🇷 · E.G.S. Luna🇧🇷

   We consider the effect of an energy-dependent dipole form factor in the high-energy behavior of the forward amplitude. The connection between the semihard parton-level dynamics and the hadron-hadron scattering is established by an eikonal QCD-based model. Our results for the proton-proton ($pp$) and antiproton-proton ($\bar{p}p$) total cross sections, ${\sigma }_{tot}^{pp,\bar{p}p}(s)$, obtained using the CTEQ6L1 parton distribution function, are consistent with the recent data from the TOTEM experiment.

   hep-phJ.Phys.Conf.Ser.(2016)·11 citations
4. 04*

   Modulation Effects in Dark Matter-Electron Scattering Experiments

   Samuel K. Lee🇺🇸 · Mariangela Lisanti🇺🇸 · Siddharth Mishra-Sharma🇺🇸 · Benjamin R. Safdi🇺🇸

   One of the next frontiers in dark-matter direct-detection experiments is to explore the MeV to GeV mass regime. Such light dark matter does not carry enough kinetic energy to produce an observable nuclear recoil, but it can scatter off electrons, leading to a measurable signal. We introduce a semi-analytic approach to characterize the resulting electron-scattering events in atomic and semiconductor targets, improving on previous analytic proposals that underestimate the signal at high recoil energies. We then use this procedure to study the time-dependent properties of the electron-scattering signal, including the modulation fraction, higher-harmonic modes and modulation phase. The time dependence can be distinct in a non-trivial way from the nuclear scattering case. Additionally, we show that dark-matter interactions inside the Earth can significantly distort the lab-frame phase-space distribution of sub-GeV dark matter.

   hep-phastro-ph.COhep-exPRD(2015)·169 citations
5. 05*

   Neutrino seesaw mechanism with texture zeros

   Jiajun Liao🇺🇸 · D. Marfatia🇺🇸 · K. Whisnant🇺🇸

   In the context of the Type I seesaw mechanism, we carry out a systematic study of the constraints that result from zeros in both the Dirac and right-handed Majorana neutrino mass matrices. We find that most constraints can be expressed in the standard form with one or two element/cofactor zeros alone, while there are 9 classes of nonstandard constraints. We show that all the constraints are stable under one-loop renormalization group running from the lightest right-handed neutrino mass scale to the electroweak scale. We study the predictions of the nonstandard constraints for the lightest neutrino mass, Dirac CP phase and neutrinoless double beta decay.

   hep-phNPB(2015)·11 citations
6. 06*

   Can dark matter - electron scattering explain the DAMA annual modulation consistent with XENON100 constraints?

   R. Foot🇦🇺

   For many years annually modulating $\sim$ keV scintillations have been observed in the DAMA/NaI and DAMA/Libra experiments. A dark matter - electron scattering interpretation is now favoured given the stringent constraints on nuclear recoil rates obtained by LUX, SuperCDMS and other experiments. Very recently, the XENON100 experiment has observed a modest annual modulation in their electron recoil events (2.8 $\sigma$ C.L.) with phase consistent with that of the DAMA experiments. However, they also found a stringent upper limit on the unmodulated rate, which suggests that any dark matter - electron scattering interpretation of these annual modulations must involve a large modulation fraction $\stackrel{>}{\sim }50\%$. Here we discuss the extent to which these results might be able to be accommodated within multi-component dark matter models featuring light dark matter particles of mass $\sim$ MeV, focusing on the mirror dark matter case for definiteness. The importance of diurnal variation as a means of testing these kinds of models is also discussed.

   hep-phastro-ph.GA5 citations
7. 07*

   New Mixing Angles in the Left-Right Symmetric Model

   Akira Kokado🇯🇵 · Takesi Saito🇯🇵

   In the left-right symmetric model neutral gauge fields are characterized by three mixing angles ${\theta }_{12},{\theta }_{23},{\theta }_{13}$ between three gauge fields $B_{\mu },W_{L\mu }^3,W_{R\mu }^3$, which produce mass eigenstates $A_{\mu },Z_{\mu },Z_{\mu }^{\prime }$, when $G=SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}\times D$ is spontaneously broken down until $U(1{)}_{em}$. We find a new mixing angle ${\theta }^{\prime }$, which corresponds to the Weinberg angle ${\theta }_W$ in the standard model with the $SU(2{)}_L\times U(1{)}_Y$ gauge symmetry, from these mixing angles. It is then shown that any mixing angle ${\theta }_{ij}$ can be expressed by $\epsilon$ and ${\theta }^{\prime }$, where $\epsilon =g_L/g_R$ is a ratio of running left-right gauge coupling strengths. We observe that light gauge bosons are described by ${\theta }^{\prime }$ only, whereas heavy gauge bosons are described by two parameters $\epsilon$ and ${\theta }^{\prime }$.

   hep-phPRD(2015)·2 citations
8. 08*

   Large N Scalars: From Glueballs to Dynamical Higgs Models

   Francesco Sannino🇩🇰

   We construct effective Lagrangians, and corresponding counting schemes, valid to describe the dynamics of the lowest lying large N stable massive composite state emerging in strongly coupled theories. The large N counting rules can now be employed when computing quantum corrections via an effective Lagrangian description. The framework allows for systematic investigations of composite dynamics of non-Goldstone nature. Relevant examples are the lightest glueball states emerging in any Yang-Mills theory. We further apply the effective approach and associated counting scheme to composite models at the electroweak scale. To illustrate the formalism we consider the possibility that the Higgs emerges as: the lightest glueball of a new composite theory; the large N scalar meson in models of dynamical electroweak symmetry breaking; the large N pseudodilaton useful also for models of near-conformal dynamics. For each of these realisations we determine the leading N corrections to the electroweak precision parameters. The results nicely elucidate the underlying large N dynamics and can be used to confront first principle lattice results featuring composite scalars with a systematic effective approach.

   hep-phhep-latPRD(2016)·8 citations
9. 09*

   The ATLAS Leptonic-$Z$ Excess from Light Squark Productions in the NMSSM Extension with a Heavy Dirac Gluino

   Ran Ding🇨🇳 · Yizhou Fan🇨🇳 · Jinmian Li🇦🇺 · Tianjun Li🇨🇳 · Bin Zhu🇨🇳

   The ATLAS Collaboration announced a 3$\sigma$ excess in the leptonic-$Z+jets+\text{met}$ channel. We show that such an excess can be interpreted in the extension of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) with a heavy Dirac gluino and light squarks. The abundant $Z$ bosons can be produced by light squark pair productions with the subsequent decays $\tilde{q}\to q{\tilde{\chi }}_2^0\to qZ{\tilde{\chi }}_1^0$. We investigate the relevant parameter space by considering the constraints from both the ATLAS and CMS direct SUSY searches. Our model can provide sufficient $Z$-signal events in large parameter space if only the ATLAS searches are considered. After combining the ATLAS and CMS searches, the maximal number of signal events can still reach about 15, which is within the $1\sigma$ region of the observed excess. For comparison, we study the conventional low energy NMSSM with a Majorana gluino and its maximal number of signal events are about 11, although we cannot realize such model in the known supersymmetry breaking scenarios.

   hep-ph4 citations
10. 10*

    Lambda production in the DIS target fragmentation region

    Federico Alberto Ceccopieri🇧🇪

    By using a recently obtained set of Lambda fracture functions, we present predictions for Lambda production in the target fragmentation region of Semi-Inclusive Deep Inelastic Scattering in CLAS@12 GeV kinematics, supplemented with a conservative error estimates. We discuss a number of observables sensitive to the assumptions of the underlying theory and many of the assumptions of the proposed phenomenological model.

    hep-phEPJC(2016)·7 citations
11. 11*

    Cogenerating and Pre-annihilating Dark Matter by a New Gauge Interaction in a Unified Model

    S.M. Barr🇺🇸 · Robert J. Scherrer🇺🇸

    Grand unified theories based on large groups (with rank greater or equal to 6 are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian interactions whose sphalerons convert baryons, leptons, and dark matter into each other, "cogenerating" a dark matter asymmetry comparable to the baryon asymmetry. In this paper it is shown that the same non-abelian interactions can "pre-annihilate" the symmetric component of heavy dark matter particles, which then decay late into light stable dark matter particles that inherit their asymmetry. It is shown that such decays can come from d=5 operators that are Planck or GUT suppressed. We derive constraints on such models and present a simple realization based on the group SU(7).

    hep-phastro-ph.COJCAP(2016)·5 citations
12. 12*

    MeV scale leptonic force for cosmic neutrino spectrum and muon anomalous magnetic moment

    Takeshi Araki🇯🇵 · Fumihiro Kaneko🇯🇵 · Toshihiko Ota🇯🇵 · Joe Sato🇯🇵 · Takashi Shimomura🇯🇵

    Characteristic patterns of cosmic neutrino spectrum reported by the IceCube collaboration and long-standing inconsistency between theory and experiment in muon anomalous magnetic moment are simultaneously explained by an extra leptonic force mediated by a gauge field with a mass of the MeV scale. With different assumptions for redshift distribution of cosmic neutrino sources, diffuse neutrino flux is calculated with the scattering between cosmic neutrino and cosmic neutrino background through the new leptonic force. Our analysis sheds light on a relation among lepton physics at the three different scales, PeV, MeV, and eV, and provides possible clues to the distribution of sources of cosmic neutrino and also to neutrino mass spectrum.

    hep-phPRD(2016)·91 citations
13. 13*

    The Edge of Jets and Subleading Non-Global Logs

    Duff Neill🇺🇸

    A persistent and fascinating problem at the high energy colliders are jets. Often trying to observe physics underlying the hard interactions at colliders requires experimental cuts in phase space, defining several jet or beam regions. QCD being a gauge theory that readily decays into infra-red modes, correlations between jet regions is almost inevitable, spoiling the predictivity of fixed order QCD calculations. One is faced with the task of calculating the evolution of a reduced density matrix, where successively less energetic (jet) regions are integrated out, to gain control of the calculation. I relate the decay rates governing the flow into the IR to an effective field theory expansion in soft jets, allowing a systematic and resummed calculation of these rates, while further relating them to physically observable features of the QCD cascade. To demonstrate the utility of the soft jet expansion, I present a factorization theorem for a soft subjet collinearly splitting in and out of a parent fat jet. Using the resummation properties of this factorization theorem, I elucidate the structure of the subleading non-global logs (encoding the jet correlations) in the hemisphere jet mass distribution, as well as give a collinear improvement of the leading order resummation equation, the BMS equation. I compare to other approaches to subleading resummation of NGLs, and find the collinear improvement of the leading order equation removes the need for kinematic-dependent corrections in the IR averaging procedure of the reduced density matrix, so that no further large logs can be generated in the IR. Finally I end with speculation about connections with collinear improvements of the NLO B-JIMWLK hierarchy for small-$x$ resummation.

    hep-phnucl-th35 citations
14. 14*

    Direct and Indirect Searches for Top-Higgs FCNC Couplings

    Hoda Hesari🇮🇷 · Hamzeh Khanpour🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

    Large top quark flavor changing through neutral currents is expected by many extensions of the standard model. Direct and indirect searches for flavor changing neutral currents (FCNC) in the top quark decays to an up type quark (up,charm) and a Higgs boson are presented. We probe the observability of the top-Higgs FCNC couplings through the process e${}^{-}$e${}^{+}\to t(\to \ell {\nu }_{\ell }b)\bar{t}(\to qH)$, where $\ell$ = e, $\mu$ and $q$ reflects up and charm quarks. It is shown that the branching ratio $Br(t\to qH)$ can be probed down to $1.12\times 10^{-3}$ at $95\%$ C.L. at the center-of-mass energy of 500 GeV with the integrated luminosity of 3000 fb${}^{-1}$. We also update the constraint on the top-Higgs FCNC coupling using the electroweak precision observables related to $Z\to c\bar{c}$ decay.

    hep-phPRD(2015)·27 citations
15. 15*

    Precise Ratios of Decay Constants of Vector over Pseudoscalar $B_{(s)}$ Mesons

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Silvano Simula🇮🇹

    The relative magnitude of the decay constants of the pseudoscalar and vector beauty mesons poses (in contrast to the case of charmed mesons) a long-standing puzzle. We revisit this problem within the framework of our recent improvements of the QCD sum-rule formalism for relating observable properties of mesons to quantum chromodynamics and are led to conclude that the decay constants of the beauty vector mesons are undoubtedly smaller than those of their pseudoscalar counterparts.

    hep-phPoS(2015)·4 citations
16. 16*

    Forward $D$ predictions for $p\mathrm{Pb}$ collisions, and sensitivity to cold nuclear matter effects

    Rhorry Gauld🇬🇧

    Predictions are provided for double differential cross sections and forward-backward ratios of $D^0$ production in $p\mathrm{Pb}$ (forward) and $\mathrm{Pb}$$p$ (backward) collisions at 5.02~TeV. The effect of nuclear corrections on the ratio of differential cross sections ratios is estimated to be $\simeq$ (10-30)\% in the kinematically accessible region of LHCb, and interestingly this ratio is approximately flat with respect to $p_T(D^0)$ due to a compensation of shadowing and anti-shadowing effects arising from the input nuclear PDFs. In comparison to $J/\psi (\to {\mu }^{-}{\mu }^{+})$ measurements which have already been performed with the available data, the cross section for $D^0(\to K^{-}{\pi }^{+})$ production is expected to be two-orders of magnitude higher.

    hep-phhep-exnucl-exPRD(2016)·18 citations
17. 17*

    Three symmetry breakings in strong and radiative decays of strange heavy mesons

    Chi-Yee Cheung🇹🇼 · Chien-Wen Hwang🇹🇼

    In this paper, we investigate three symmetry breaking effects in strong and radiative decays of strange heavy mesons. We study 1/m_Q corrections within the heavy quark effect theory, as well as SU(3) and SU(2) symmetry breakings induced by light quark mass differences and the \eta-\pi mixing vertex. These effects are studied in a covariant model. The numerical results show that the 1/m_Q corrections of the coupling constants are consistent with \alpha_s \Lambda_{QCD}/m_Q. The SU(3) symmetry violating effect of the strong coupling constant is obviously larger than that of the magnetic coupling constant. The value of the \eta-\pi mixing vertex has some changes because of the renewed data. As compared with the other theoretical calculations and the experimental data, our radiative decay rates are much larger than those of the other theoretical methods, except for \chiPT; however, our branching ratios are close to the experimental data.

    hep-phEPJC(2016)·8 citations
18. 18*

    Walking on the Ladder: 125 GeV Technidilaton, or Conformal Higgs -Dedicated to the late Professor Yoichiro Nambu-

    Shinya Matsuzaki🇯🇵 · Koichi Yamawaki🇯🇵

    The walking technicolor based on the ladder Schwinger-Dyson gap equation is studied, with the scale-invariant coupling being an idealization of the Caswell-Banks-Zaks infrared fixed point in the "anti-Veneziano limit", such that $N_C\to \infty$ with $N_C\cdot \alpha ({\mu }^2)=$ fixed and $N_F/N_C=$ fixed ($\gg 1$), of the $SU(N_C)$ gauge theory with massless $N_F$ flavors near criticality. We show that the 125 GeV Higgs can be naturally identified with the technidilaton (TD) predicted in the walking technicolor, a pseudo Nambu-Goldstone (NG) boson of the spontaneous symmetry breaking of the approximate scale symmetry. Ladder calculations yield the TD mass $M_{\varphi }$ from the trace anomaly as $M_{\varphi }^2{F}_{\varphi }^2=-4⟨{\theta }_{\mu }^{\mu }⟩=-\frac{\beta (\alpha ({\mu }^2))}{\alpha ({\mu }^2)}⟨G_{\lambda \nu }^2({\mu }^2)⟩\simeq N_C{N}_F\frac{16}{{\pi }^4}{m}_F^4$, independently of the renormalization point $\mu$, where $m_F$ is the dynamical mass of the technifermion, and $F_{\varphi }=\mathcal{O}(\sqrt{N_F{N}_C}{m}_F)$ the TD decay constant. It reads $M_{\varphi }^2\simeq (\frac{v_{\mathrm{EW}}}{2}\cdot \frac{5v_{\mathrm{EW}}}{F_{\varphi }}{)}^2\cdot [\frac{8}{N_F}\frac{4}{N_C}]$, ($v_{\mathrm{EW}}=246$ GeV), which implies $F_{\varphi }\simeq 5v_{\mathrm{EW}}$ for $M_{\varphi }\simeq 125\mathrm{GeV}\simeq \frac{1}{2}{v}_{\mathrm{EW}}$ in the one-family model ($N_C=4,N_F=8$), in good agreement with the current LHC Higgs data. The result reflects a generic scaling $M_{\varphi }^2/v_{\mathrm{EW}}^2\sim M_{\varphi }^2/F_{\varphi }^2\sim m_F^2/F_{\varphi }^2\sim 1/(N_F{N}_C)\to 0$ as a vanishing trace anomaly, namely the TD has a mass vanishing in the anti-Veneziano limit, similarly to ${\eta }^{\prime }$ meson as a pseudo-NG boson of the ordinary QCD with vanishing $U(1{)}_A$ anomaly in the Veneziano limit ($N_F/N_C\ll 1$).

    hep-phJHEP(2015)·26 citations
19. 19*

    Naturalness and Renormalization Group in the Standard Model

    Grigorii B. Pivovarov🇷🇺

    I define a naturalness criterion formalizing the intuitive notion of naturalness discussed in the literature. After that, using ${\varphi }^4$ as an example, I demonstrate that a theory may be natural in the $MS$-scheme and, at the same time, unnatural in the Gell-Mann--Low scheme. Finally, I discuss the prospects of using a version of the Gell-Mann--Low scheme in the Standard Model.

    hep-phhep-thInt.J.Mod.Phys.A(2016)·1 citation
20. 20*

    BFKL predictions for inclusive three jet production at the LHC

    F. Caporale🇪🇸 · G. Chachamis🇪🇸 · B. Murdaca🇮🇹 · A. Sabio Vera🇪🇸

    We define new observables sensitive to BFKL dynamics in the context of multijet production at the large hadron collider (LHC). We propose the study of the inclusive production of three jets well separated in rapidity from each other, with two of them being very forward. We show that the tagging of a third jet in the central region of rapidity allows for a very strong test of the BFKL formalism. In particular, we have studied two projections on azimuthal angles for the differential cross section which allow for the definition of many different observables whose behavior when varying the $p_t$ and rapidity of the central jet is a distinct signal of BFKL dynamics. In order to reduce the theoretical uncertainties and influence of higher order corrections, we propose the study of ratios of correlation functions of products of cosines of azimuthal angle differences among the tagged jets.

    hep-phPRL(2016)·80 citations
21. 21*

    Progress in the NNPDF global analysis and the impact of the legacy HERA combination

    Juan Rojo🇬🇧

    The H1 and ZEUS collaborations have recently presented their final results for the combination of inclusive cross-section measurements taken during Run I and Run II at the HERA collider. In this contribution, following an overview of recent progress in the NNPDF framework, we quantify the impact of the legacy HERA dataset on the NNPDF3.0 analysis, finding that it has a very moderate effect in the global fit. On the other hand, we also find that a HERA-only fit using the legacy dataset leads to a rather more accurate determination of PDFs as compared to a fit including only the HERA-I data. We also explore the sensitivity of the fit with respect to kinematical cuts in the small-x and small-Q region, finding hints of a possible tension between data and theory.

    hep-phhep-exPoS(2015)·17 citations
22. 22*

    Charge-conjugation symmetric complete impulse approximation for the pion electromagnetic form factor in the Covariant Spectator Theory

    Elmar P. Biernat🇵🇹 · Franz Gross🇺🇸 · M. T. Peña🇵🇹 · Alfred Stadler🇵🇹

    The pion form factor is calculated in the framework of the charge-conjugation invariant Covariant Spectator Theory. This formalism is established in Minkowski space and the calculation is set up in momentum space. In a previous calculation we included only the leading pole coming from the spectator quark (referred to as the relativistic impulse approximation). In this paper we also include the contributions from the poles of the quark which interacts with the photon and average over all poles in both the upper and lower half planes in order to preserve charge conjugation invariance (referred to as the $C$-symmetric complete impulse approximation). We find that for small pion mass these contributions are significant at all values of the four-momentum transfer $Q^2$ but, surprisingly, do not alter the shape obtained from the spectator poles alone.

    hep-phnucl-thPRD(2015)·18 citations
23. 23*

    Treating jet correlations in high pile-up at hadron colliders

    F. Hautmann🇬🇧 · H. Jung🇩🇪 · H. Van Haevermaet🇧🇪

    Experiments in the high-luminosity runs at the Large Hadron Collider face the challenges of very large pile-up. Primary techniques to deal with this are based on precise vertex and track reconstruction. Outside tracker acceptances, however, lie regions of interest for many aspects of the LHC physics program. We explore complementary approaches to pile-up treatment and propose a data-driven jet-mixing method which can be used outside tracker acceptances without depending on Monte Carlo generators. The method can be applied to treat correlation observables and take into account, besides the jet transverse momentum pedestal, effects of hard jets from pile-up.

    hep-phPLB(2016)·6 citations
24. 24*

    Two-loop electroweak vertex corrections for polarized Møller scattering

    A.G. Aleksejevs🇨🇦 · S.G. Barkanova🇨🇦 · Yu.M. Bystritskiy🇷🇺 · E.A. Kuraev🇷🇺 · V.A. Zykunov🇧🇾

    The contributions to the electron-electron-photon vertex of two-loop electroweak corrections are calculated. The relative correction to the parity-violating asymmetry of Møller scattering for the case of 11 GeV electron scattered off the electron at rest is found to be about -0.0034 and should be taken into account at future experiment MOLLER at JLab.

    hep-phPhys.Part.Nucl.Lett.(2016)·10 citations
25. 25*

    Infrared multiphoton resummation in quantum electrodynamics

    P. Mati🇭🇺

    Infrared singularities in massless gauge theories are known since the foundation of quantum field theories. The root of this problem can be tracked back to the very definition of these long-range interacting theories such as QED. It can be shown that singularities are caused by the massless degrees of freedom (i.e. the photons in the case of QED). In the Bloch-Nordsieck model the absence of the infrared catastrophe can be shown exactly by the complete summation of the radiative corrections. In this paper we will give the idea of the derivation of the Bloch-Nordsieck propagator, that describes the infrared structure of the electron propagation, at zero and finite temperatures. Some ideas of the possible applications are also mentioned.

    hep-phhep-thNucl.Instrum.Meth.B(2016)·2 citations
26. 26*

    Influence of the inverse magnetic catalysis and the vector interaction in the location of the critical end point

    Pedro Costa🇵🇹 · Márcio Ferreira🇵🇹 · Débora P. Menezes🇧🇷 · João Moreira🇵🇹 · Constança Providência🇵🇹

    The effect of a strong magnetic field on the location of the critical end point (CEP) in the QCD phase diagram is discussed under different scenarios. In particular, we consider the contribution of the vector interaction and take into account the inverse magnetic catalysis obtained in lattice QCD calculations at zero chemical potential. The discussion is realized within the (2+1) Polyakov--Nambu--Jona-Lasinio model. It is shown that the vector interaction and the magnetic field have opposite competing effects, and that the winning effect depends strongly on the intensity of the magnetic field. The inverse magnetic catalysis at zero chemical potential has two distinct effects for magnetic fields above $\gtrsim 0.3$ GeV${}^2$: it shifts the CEP to lower chemical potentials, hinders the increase of the CEP temperature and prevents a too large increase of the baryonic density at the CEP. For fields $eB<0.1$ GeV${}^2$ the competing effects between the vector contribution and the magnetic field can move the CEP to regions of temperature and density in the phase diagram that could be more easily accessible to experiments.

    hep-phPRD(2015)·54 citations
27. 27*

    Iso-spin asymmetry of quark distributions and implications for single top-quark production at the LHC

    S. Alekhin🇩🇪 · J. Bluemlein🇩🇪 · S. Moch🇩🇪 · R. Placakyte🇩🇪

    We present an improved determination of the up- and down-quark distributions in the proton using recent data on charged lepton asymmetries from $W^{\pm }$ gauge-boson production at the LHC and Tevatron. The analysis is performed in the framework of a global fit of parton distribution functions. The fit results are consistent with a non-zero iso-spin asymmetry of the sea, $x(\bar{d}-\bar{u})$, at small values of Bjorken $x\sim 10^{-4}$ indicating a delayed onset of the Regge asymptotics of a vanishing $(\bar{d}-\bar{u})$-asymmetry at small-$x$. We compare with up- and down-quark distributions available in the literature and provide accurate predictions for the production of single top-quarks at the LHC, a process which can serve as a standard candle for the light quark flavor content of the proton.

    hep-phPRD(2016)·42 citations
28. 28*

    Leptogenesis in an SU(5) x A5 Golden Ratio Flavour Model: Addendum

    Julia Gehrlein🇩🇪 · Serguey T. Petcov🇮🇹 · Martin Spinrath🇩🇪 · Xinyi Zhang🇨🇳

    We derive and discuss the solution of the Boltzmann equations for leptogenesis in a phenomenologically viable SU(5) x A5 golden ratio flavour model proposed in arXiv:1410.2057 [hep-ph], arXiv:1502.00110 [hep-ph] . The model employs, in particular, the seesaw mechanism of neutrino mass generation. We find that the results on the baryon asymmetry of the Universe, obtained earlier in arXiv:1502.00110 [hep-ph] using approximate analytic expressions for the relevant CP violating asymmetry and efficiency factors, are correct, as was expected, up to 20-30 %. The phenomenological predictions for the low energy neutrino observables, derived using values of the parameters of the model for which we reproduce the observed value of the baryon asymmetry, change little with respect to those presented in arXiv:1502.00110 [hep-ph]. Among the many predictions of the model we find, for instance, that the neutrinoless double beta decay effective Majorana mass m_ee lies between 3.3 meV and 14.3 meV.

    hep-phNPB(2015)·25 citations
29. 29*

    Lattice studies of charmonia and exotics

    Sasa Prelovsek🇸🇮

    The lattice QCD simulations of charmonia and exotic charmonium-like states are reviewed. I report on the first exploratory simulation of charmonium resonances above open charm threshold which takes into account the strong decay. The puzzles related to the first-excited scalar charmonia are discussed. Evidence for X(3872) is presented along with investigation of its Fock components. The $Z_c^{+}(3900)$ seems to emerge from the HALQCD approach as a result of the coupled channel effect $J/\psi \pi -D{\bar{D}}^{\ast }$. The indication for the pentaquark bound state ${\eta }_{c}N$ is presented.

    ↳ hep-lathep-ph12 citations
30. 30*

    Early formed astrophysical objects and cosmological antimatter

    A.D. Dolgov🇷🇺

    Astronomical observations of recent years show that the universe at high redshifts about ten is densely populated by the early formed objects: bright galaxies, quasars, gamma-bursters, and contains a lot of metals and dust. Such rich early formed varieties have not been expected in the standard model of formation of astrophysical objects. There is serious tension between the standard theory and observations.We describe the model which naturally relaxes this tension and nicely fits the data. The model naturally leads to creation of cosmologically significant antimatter which may be abundant even in the Galaxy. Phenomenological consequences of our scenario and possibility of distant registration of antimatter are discussed.

    ↳ astro-ph.COhep-ph6 citations
31. 31*

    Quantum Loops in Non-Local Gravity

    Spyridon Talaganis🇬🇧

    In this proceedings, I will consider quantum aspects of a non-local, infinite-derivative scalar field theory - a $toymodel$ depiction of a covariant infinite-derivative, non-local extension of Einstein's general relativity which has previously been shown to be free from ghosts around the Minkowski background. The graviton propagator in this theory gets an exponential suppression making it $asymptoticallyfree$, thus providing strong prospects of resolving various classical and quantum divergences. In particular, I will find that at $1$-loop, the $2$-point function is still divergent, but once this amplitude is renormalized by adding appropriate counter terms, the ultraviolet (UV) behavior of all other $1$-loop diagrams as well as the $2$-loop, $2$-point function remains well under control. I will go on to discuss how one may be able to generalize our computations and arguments to arbitrary loops.

    ↳ hep-thastro-ph.COgr-qchep-phPoS(2015)·3 citations
32. 32*

    Supersymmetric asymptotic safety is not guaranteed

    Kenneth Intriligator🇺🇸 · Francesco Sannino🇩🇰

    It was recently shown that certain perturbatively accessible, non-supersymmetric gauge-Yukawa theories have UV asymptotic safety, without asymptotic freedom: the UV theory is an interacting RG fixed point, and the IR theory is free. We here investigate the possibility of asymptotic safety in supersymmetric theories, and use unitarity bounds, and the a-theorem, to rule it out in broad classes of theories. The arguments apply without assuming perturbation theory. Therefore, the UV completion of a non-asymptotically free susy theory must have additional, non-obvious degrees of freedom, such as those of an asymptotically free (perhaps magnetic dual) extension.

    ↳ hep-thhep-lathep-phJHEP(2015)·49 citations
33. 33*

    Studies of Charmonium at BESIII

    BESIII Collaboration (Rong-Gang Ping for the collaboration)

    Based on $\psi (3686)$ decays of 106 million, the 1.31 billion J/psi events and a data sample of $\psi (3770)$ with $2.9f{b}^{-1}$ integrated luminosity, many analyses are performed. Exclusively baryonic decays of the $\psi (3770)$, the radiative transition $\psi (3770)\to \gamma {\eta }_c(2S)$, the $\psi (3770)$ transition to ${\chi }_{cJ}$, isospin violation decay ${\chi }_{c0,2}\to {\pi }^0{\eta }_c$, the $C-$parity violation decays $J/\psi \to \gamma \gamma ,\gamma \varphi$ are searched for, but no significant signals are observed, and upper limits are set for these decays. The decays of $\psi (3770)\to \gamma {\chi }_{c1}$ and $J/\psi \to {\pi }^0\varphi$ signals are observed. These measurements provide more information on the charmonium structure, and the isospin and $C$-parity violation in the charmonium decays.

    ↳ hep-exhep-ph0 citations
34. 34*

    ALP hints from cooling anomalies

    Maurizio Giannotti🇺🇸

    We review the current status of the anomalies in stellar cooling and argue that, among the new physics candidates, an axion-like particle would represent the best option to account for the hinted additional cooling.

    ↳ astro-ph.HEhep-ph14 citations
35. 35*

    Two Nucleon Systems at $m_{\pi }\sim 450\mathrm{MeV}$ from Lattice QCD

    Kostas Orginos🇺🇸 · Assumpta Parreno🇪🇸 · Martin J. Savage🇺🇸 · Silas R. Beane🇺🇸 · Emmanuel Chang🇺🇸 · William Detmold🇺🇸

    Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of $m_{\pi }\sim 450\mathrm{MeV}$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $B_d=14.4_{-2.6}^{+3.2}\mathrm{MeV}$, while the dineutron is bound by $B_{nn}=12.5_{-5.0}^{+3.0}\mathrm{MeV}$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. The extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann--Okubo mass relation. [An Erratum to the published version is included as an appendix. It details the impact of an error discovered in 2020 and corrects typographical errors.]

    ↳ hep-lathep-phnucl-thPRD(2015)·167 citations
36. 36*

    Analytical solution for Klein-Gordon equation and action function of the solution for Dirac equation in counter-propagating laser waves

    Huayu Hu🇨🇳 · Jie Huang🇨🇳

    Nonperturbative calculation of QED processes participated by a strong electromagnetic field, especially provided by strong laser facilities at present and in the near future, generally resorts to the Furry picture with the usage of analytical solutions of the particle dynamical equation, such as the Klein-Gordon equation and Dirac equation. However only for limited field configurations such as a plane-wave field could the equations be solved analytically. Studies have shown significant interests in QED processes in a strong field composed of two counter-propagating laser waves, but the exact solutions in such a field is out of reach. In this paper, inspired by the observation of the structure of the solutions in a plane-wave field, we develop a new method and obtain the analytical solution for the Klein-Gordon equation and equivalently the action function of the solution for the Dirac equation in this field, under a largest dynamical parameter condition that there exists an inertial frame in which the particle free momentum is far larger than the other field dynamical parameters. The applicable range of the new solution is demonstrated and its validity is proven clearly. The result has the advantage of Lorentz covariance, clear structure and close similarity to the solution in a plane-wave field, and thus favors convenient application.

    ↳ physics.plasm-phhep-phPRA(2015)·11 citations
37. 37*

    Critical line of 2+1 flavor QCD: Toward the continuum limit

    Paolo Cea🇮🇹 · Leonardo Cosmai🇮🇹 · Alessandro Papa🇮🇹

    We determine the continuum limit of the curvature of the pseudocritical line of QCD with $n_f$=2+1 staggered fermions at nonzero temperature and quark density. We perform Monte Carlo simulations at imaginary baryon chemical potentials, adopting the HISQ/tree action discretization, as implemented in the code by the MILC collaboration. Couplings are adjusted so as to move on a line of constant physics, as determined in Ref.~\cite{Bazavov:2011nk}, with the strange quark mass $m_s$ fixed at its physical value and a light-to-strange mass ratio $m_l/m_s=1/20$. The chemical potential is set at the same value for the three quark species, ${\mu }_l={\mu }_s\equiv \mu$. We attempt an extrapolation to the continuum using the results on lattices with temporal size up to $L_t=12$. Our estimate for the continuum value of the curvature $\kappa$ at zero baryon density, $\kappa =0.020(4)$, is compared with recent lattice results and with experimental determinations of the freeze-out curve.

    ↳ hep-lathep-phnucl-thPRD(2016)·112 citations
38. 38*

    Transverse-target-spin asymmetry in exclusive $\omega$-meson electroproduction

    The HERMES Collaboration: A. Airapetian🇩🇪 · N. Akopov🇦🇲 · Z. Akopov🇩🇪 · E.C. Aschenauer🇺🇸 · W. Augustyniak🇵🇱 · A. Avetissian🇦🇲 · S. Belostotski🇷🇺 · H.P. Blok🇳🇱 · A. Borissov🇩🇪 · V. Bryzgalov🇷🇺 · G.P. Capitani🇮🇹 · G. Ciullo🇮🇹 and 83 other authors

    Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi \omega$ transition form factor.

    ↳ hep-exhep-phEPJC(2015)·11 citations
39. 39*

    Construction of KbarN potential and structure of Lambda(1405) based on chiral unitary approach

    Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵

    Based on chiral unitary approach, we construct the realistic KbarN local potential, which is useful for the quantitative calculation of Kbar-nuclei. Since the resonance pole structure of the KbarN system seems important for the Kbar-nuclei and the spacial structure of Lambda(1405), we establish the construction procedure of the local potential paying attention to the scattering amplitude in the complex energy plane. Furthermore, for the quantitative study of the Kbar-nuclei, we consider the constraint from the recent experimental data measured by SIDDHARTA, which significantly reduces the uncertainty of the KbarN amplitude. With this new local potential, we estimate the spacial structure of Lambda(1405) and obtain the result indicating the meson-baryon molecular state of Lambda(1405).

    ↳ nucl-thhep-phJPS Conf.Proc.(2016)·5 citations
40. 40*

    Towards conformal cosmology

    M. Libanov🇷🇺 · V. Rubakov🇷🇺 · G. Rubtsov🇷🇺

    Approximate de Sitter symmetry of inflating Universe is responsible for the approximate flatness of the power spectrum of scalar perturbations. However, this is not the only option. Another symmetry which can explain nearly scale-invariant power spectrum is conformal invariance. We give a short review of models based on conformal symmetry which lead to the scale-invariant spectrum of the scalar perturbations. We discuss also potentially observable features of these models.

    ↳ hep-thastro-ph.COgr-qchep-phJETP Lett.(2015)·11 citations
41. 41*

    Possibility of DCC formation in pp collisions at LHC energy via reaction-diffusion equation

    Partha Bagchi🇮🇳 · Arpan Das🇮🇳 · Srikumar Sengupta🇮🇳 · Ajit M. Srivastava🇮🇳

    There are indications of formation of a thermalized medium in high multiplicity pp collisions at LHC energy. It is possible that such a medium may reach high enough energy density/temperature so that a transient stage of quark-gluon plasma, where chiral symmetry is restored, may be achieved. Due to rapid 3-dimensional expansion, the system will quickly cool undergoing spontaneous chiral symmetry breaking transition. We study the dynamics of chiral field, after the symmetry breaking transition, for such an event using reaction-diffusion equation approach which we have recently applied for studying QCD transitions in relativistic heavy-ion collisions. We show that the interior of such a rapidly expanding system is likely to lead to the formation of a single large domain of disoriented chiral condensate (DCC) which has been a subject of intensive search in earlier experiments. We argue that large multiplicity pp collisions naturally give rise to required boundary conditions for the existence of slowly propagating front solutions of reaction-diffusion equation with resulting dynamics of chiral field leading to the formation of a large DCC domain.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2016)·1 citation
42. 42*

    BUSSTEPP lecture notes: Exact Wilsonian Renormalisation

    J. Alexandre🇬🇧

    These lecture notes introduce exact Wilsonian renormalisation, and describe its technical approach, from an intuitive implementation to more advanced realisations. The methods and concepts are explained with a scalar theory, and their extension to quantum gravity is discussed as an application.

    ↳ hep-thhep-ph4 citations
43. 43*

    Supernovae as cosmological probes

    Jeppe Trost Nielsen🇩🇰

    The cosmological standard model at present is widely accepted as containing mainly things we do not understand. In particular the appearance of a Cosmological Constant, or dark energy, is puzzling. This was first inferred from the Hubble diagram of a low number of Type Ia supernovae, and later corroborated by complementary cosmological probes. Today, a much larger collection of supernovae is available, and here I perform a rigorous statistical analysis of this dataset. Taking into account how the supernovae are calibrated to be standard candles, we run into some subtleties in the analysis. To our surprise, this new dataset - about an order of bigger than the size of the original dataset - shows, under standard assumptions, only mild evidence of an accelerated universe.

    ↳ astro-ph.COastro-ph.IMhep-ph3 citations
44. 44*

    Single Freeze-Out, Statistics and Pion, Kaon and Proton Production in Central Pb-Pb Collisions at $\sqrt{s_{NN}}=2.76$ TeV

    Dariusz Prorok🇵🇱

    Many data in the high energy physics are, in fact, sample means. It is shown that when this exact meaning of the data is taken into account and the most weakly bound states are removed from the hadron resonance gas, the acceptable fit to the whole spectra of pions, kaons and protons measured at midrapidity in central Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV [Phys.Rev.Lett.109,252301(2012)] is obtained. The invariant distributions are predicted with the help of the single-freeze-out model in the chemical equilibrium framework. Low $p_T$ pions and protons are reproduced simultaneously as well as $p/\pi$ ratio. Additionally, correct predictions extend over lower parts of large $p_T$ data. Some more general, possible implications of this approach are pointed out.

    ↳ nucl-thhep-exhep-phnucl-exJ.Phys.G(2016)·12 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.