Tue·May 24, 2016Tuesday·May 24, 2016

1. 01*

   Extending the Reach of Compressed Gluinos at the LHC

   Antonio Delgado🇺🇸 · Adam Martin🇺🇸 · Nirmal Raj🇺🇸

   Conventional supersymmetry searches rely on large missing momentum and, on that account, are unsuitable for discovering superpartners nearly degenerate with the LSP. Such "compressed regions" are best probed by dedicated strategies that exploit their unique kinematic features. We consider a case study of a compressed gluino-bino simplified spectrum, motivated by its ability to set the dark matter relic abundance via co-annihilation. A kinematic variable suited to this spectrum is introduced, by which, for a gluino-bino mass splitting of 100 GeV, the discovery reach is extendable to m(gluino) = 850 GeV (1370 GeV) at LHC center-of-mass energy 8 TeV (13 TeV) with luminosity 20 inverse fb (3000 inverse fb). The non-trivial role played by soft triggers is also discussed.

   hep-phPRD(2016)·7 citations
2. 02*

   Updated constraints on velocity and momentum-dependent asymmetric dark matter

   Aaron C. Vincent (Durham U., IPPP)🇬🇧 · Pat Scott (Imperial Coll., London)🇬🇧 · Aldo Serenelli (ICE/CSIC-IEEC)🇪🇸

   We present updated constraints on dark matter models with momentum-dependent or velocity-dependent interactions with nuclei, based on direct detection and solar physics. We improve our previous treatment of energy transport in the solar interior by dark matter scattering, leading to significant changes in fits to many observables. Based on solar physics alone, DM with a spin-independent $q^4$ coupling provides the best fit to data, and a statistically satisfactory solution to the solar abundance problem. Once direct detection limits are accounted for however, the best solution is spin-dependent $v^2$ scattering with a reference cross-section of 10${}^{-35}$ cm${}^2$ (at a reference velocity of $v_0=220$ km s${}^{-1}$), and a dark matter mass of about 5 GeV.

   hep-phastro-ph.COastro-ph.SRJCAP(2016)·30 citations
3. 03*

   Short-baseline neutrino oscillations, Planck, and IceCube

   John F. Cherry (Virginia Tech.)🇺🇸 · Alexander Friedland (SLAC)🇺🇸 · Ian M. Shoemaker (Penn State U.)🇺🇸

   We examine a framework with light new physics, which couples to the Standard Model only via neutrino mixing. Taking the hints from the short-baseline anomalies seriously and combining them with modern cosmological data and recent IceCube measurements, we obtain surprisingly effective constraints on the hidden force: keV $\lesssim M\lesssim 0.3$ GeV for the mediator mass and $g_h>10^{-6}-10^{-3}$ for the coupling constant. Flavor equilibration between the hidden and active neutrinos can be delayed until temperatures of $\sim 1$ MeV, but not below $\sim 100$ keV. This scenario can be tested with next-generation Cosmic Microwave Background, IceCube, and oscillation experiments.

   hep-phastro-ph.COastro-ph.HE85 citations
4. 04*

   Electroweakino pair production at the LHC: NLO SUSY-QCD corrections and parton-shower effects

   Julien Baglio🇩🇪 · Barbara Jäger🇩🇪 · Matthias Kesenheimer🇩🇪

   We present a set of NLO SUSY-QCD calculations for the pair production of neutralinos and charginos at the LHC, and their matching to parton-shower programs in the framework of the POWHEG-BOX program package. The code we have developed provides a SUSY Les Houches Accord interface for setting supersymmetric input parameters. Decays of the neutralinos and charginos and parton-shower effects can be simulated with PYTHIA. To illustrate the capabilities of our program, we present phenomenological results for a representative SUSY parameter point. We find that NLO-QCD corrections increase the production rates for neutralinos and charginos significantly. The impact of parton-shower effects on distributions of the weakinos is small, but non-negligible for jet distributions.

   hep-phhep-exJHEP(2016)·15 citations
5. 05*

   Complementarity of DM Searches in a Consistent Simplified Model: the Case of Z'

   Thomas Jacques🇮🇹 · Andrey Katz🇨🇭 · Enrico Morgante🇨🇭 · Davide Racco🇨🇭 · Mohamed Rameez🇨🇭 · Antonio Riotto🇨🇭

   We analyze the constraints from direct and indirect detection on fermionic Majorana Dark Matter (DM). Because the interaction with the Standard Model (SM) particles is spin-dependent, a priori the constraints that one gets from neutrino telescopes, the LHC, direct and indirect detection experiments are comparable. We study the complementarity of these searches in a particular example, in which a heavy $Z^{\prime }$ mediates the interactions between the SM and the DM. We find that for heavy dark matter indirect detection provides the strongest bounds on this scenario, while IceCube bounds are typically stronger than those from direct detection. The LHC constraints are dominant for smaller dark matter masses. These light masses are less motivated by thermal relic abundance considerations. We show that the dominant annihilation channels of the light DM in the Sun and the Galactic Center are either $b\bar{b}$ or $t\bar{t}$, while the heavy DM annihilation is completely dominated by $Zh$ channel. The latter produces a hard neutrino spectrum which has not been previously analyzed. We study the neutrino spectrum yielded by DM and recast IceCube constraints to allow proper comparison with constraints from direct and indirect detection experiments and LHC exclusions. Note that the original version of the paper contains an important error: the contribution of the $Z$-mediated processes was overlooked. This changes some of the results of the paper. For the details and the correct results please see the erratum attached to this file as an appendix.

   hep-phastro-ph.COastro-ph.HEJHEP(2016)·63 citations
6. 06*

   A Determination of the Charm Content of the Proton

   The NNPDF Collaboration: Richard D.Ball🇬🇧 · Valerio Bertone🇬🇧 · Marco Bonvini🇬🇧 · Stefano Carrazza🇨🇭 · Stefano Forte🇮🇹 · Alberto Guffanti🇮🇹 · Nathan P. Hartland🇬🇧 · Juan Rojo🇬🇧 · Luca Rottoli🇬🇧

   We present an unbiased determination of the charm content of the proton, in which the charm parton distribution function (PDF) is parametrized on the same footing as the light quarks and the gluon in a global PDF analysis. This determination relies on the calculation of deep-inelastic structure functions in the FONLL scheme, generalized to account for massive charm-initiated contributions. In contrast to the usual situation in which the charm PDF is assumed to be generated perturbatively by pair radiation off gluons and light quarks, vanishing at a scale set by the value of the charm mass m_c, we find that the fitted charm PDF vanishes within uncertainties at a scale Q~1.5 GeV for all x<~0.1, independent of the value of m_c used in the coefficient functions. We also find some evidence that the charm PDF at large x>~0.1 and low scales does not vanish, but rather has an "intrinsic" component, very weakly scale dependent and almost independent of the value of m_c, carrying about 1% of the total momentum of the proton. The uncertainties in all other PDFs are only slightly increased by the inclusion of fitted charm, while the dependence of these PDFs on m_c is significantly reduced. When the EMC charm structure function dataset is included, it is well described by the fit, and PDF uncertainties in the fitted charm PDF are significantly reduced, though we verify that excluding the EMC data does not qualitatively modify any of our findings. The increased stability with respect to m_c persists at high scales and is the main implication of our results for LHC phenomenology. Fitting the charm PDF modifies the predictions for processes such as high p_T and large rapidity charm pair production and Z+c production, and thus we expect that future LHC data will further constrain the charm content of the proton.

   hep-phhep-exEPJC(2016)·142 citations
7. 07*

   Texture zeros in neutrino mass matrix

   Bartosz Dziewit🇵🇱 · Jacek Holeczek🇵🇱 · Monika Richter🇵🇱 · Sebastian Zając🇵🇱 · Marek Zrałek🇵🇱

   The Standard Model does not explain the hierarchy problem. Before the discovery of nonzero lepton mixing angle {\theta}13 high hopes in explanation of the shape of the lepton mixing matrix were combined with non abelian symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is still valid. Texture zeroes, that are combined with abelian symmetries, are intensively studied. The neutrino mass matrix is a natural way to study such symmetries.

   hep-phPhys.Atom.Nucl.(2017)·5 citations
8. 08*

   The flavour problem and family symmetry beyond the Standard Model

   Bartosz Dziewit🇵🇱 · Jacek Holeczek🇵🇱 · Monika Richter🇵🇱 · Sebastian Zając🇵🇱 · Marek Zrałek🇵🇱

   In the frame of two Higgs doublet model we try to explain the lepton masses and mixing matrix elements assuming that neutrinos are Dirac particles. Discrete family symmetry groups, which are subgroups of U(3) up to the 1025 order are considered. Like in the one Higgs Standard Model, we found that discrete family symmetries do not give satisfactory answer for this basic questions in the flavour problem.

   hep-phActa Phys.Polon.B(2015)·3 citations
9. 09*

   Propagators of resonances and rescatterings of the decay products

   A.V. Anisovich · V.V. Anisovich · M.A. Matveev🇷🇺 · A.V. Sarantsev🇷🇺 · A.N. Semenova🇷🇺 · J. Nyiri🇭🇺

   Hadronic resonance propagators which take into account the analytical properties of decay processes are built in terms of the dispersion relation technique. Such propagators can describe multi-component systems, for example, those when quark degrees of freedom create a resonance state, and decay products correct the corresponding pole by adding hadronic deuteron-like components. Meson and baryon states are considered, examples of particles with different spins are presented.

   hep-phInt.J.Mod.Phys.A(2016)·0 citations
10. 10*

    Mapping color fluctuations in the photon in ultraperipheral heavy ion collisions at the Large Hadron Collider

    M. Alvioli (Perugia U.)🇮🇹 · L. Frankfurt (Tel Aviv U. and Penn State U.)🇮🇱 · V. Guzey (PNPI)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (PNPI)🇷🇺

    We model effects of color fluctuations (CFs) in the light-cone photon wave function and for the first time make predictions for the distribution over the number of wounded nucleons $\nu$ in the inelastic photon-nucleus scattering. We show that CFs lead to a dramatic enhancement of this distribution at $\nu =1$ and large $\nu >10$. We also study the implications of different scales and CFs in the photon wave function on the total transverse energy $\Sigma E_T$ and other observables in inelastic $\gamma A$ scattering with different triggers. Our predictions can be tested in proton-nucleus and nucleus-nucleus ultraperipheral collisions at the LHC and will help to map CFs, whose first indications have already been observed at the LHC.

    hep-phhep-exnucl-exPLB(2017)·11 citations
11. 11*

    Michel parameters in radiative muon decay

    A.B. Arbuzov🇷🇺 · T.V. Kopylova🇷🇺

    Radiative muon and tau lepton decays are described within the model-independent approach with the help of generalized Michel parameters. The exact dependence on charged lepton masses is taken into account. The results are relevant for modern and future experiments on muon and tau lepton decays.

    hep-phJHEP(2016)·21 citations
12. 12*

    Numerical integration of subtraction terms

    Satyajit Seth🇩🇪 · Stefan Weinzierl🇩🇪

    Numerical approaches to higher-order calculations often employ subtraction terms, both for the real emission and the virtual corrections. These subtraction terms have to be added back. In this paper we show that at NLO the real subtraction terms, the virtual subtraction terms, the integral representations of the field renormalisation constants and -- in the case of initial-state partons -- the integral representation for the collinear counterterm can be grouped together to give finite integrals, which can be evaluated numerically. This is useful for an extension towards NNLO.

    hep-phPRD(2016)·31 citations
13. 13*

    Higgs Boson Mass and Muon g-2 with Strongly Coupled Vector-like Generations

    Michinobu Nishida🇯🇵 · Koichi Yoshioka🇯🇵

    We study the Higgs boson mass and the muon anomalous magnetic moment (the muon $g-2$) in a supersymmetric standard model with vector-like generations. The infrared physics of the model is governed by strong renormalization-group effects of the gauge couplings. That leads to sizable extra Yukawa couplings of Higgs doublets between the second and vector-like generations in both quark and lepton sectors. It is found with this property that there exist wide parameter regions where the Higgs boson mass and the muon $g-2$ are simultaneously explained.

    hep-phPRD(2016)·9 citations
14. 14*

    Triangle diagram in heavy-baryon chiral perturbation theory

    Songlin Lyu🇨🇳 · Bingwei Long🇨🇳

    The pion-baryon triangle diagram is inspected for a special kinematic region where the squared momentum transfer $t$ is close to $4m_{\pi }^2$: $|t-4m_{\pi }^2|\lesssim m_{\pi }^4/m_N^2$. Instead of arguing on the ground of anomalous threshold, we investigate possible impacts on power counting. The pion can have very small energies, as opposed to $\sim m_{\pi }$ in the physical region, which allows all three propagators to be extremely near their mass shell and contributes significantly to the loop integral. We find that in this narrow kinematic window the static-limit approximation for the baryon propagator is invalid and the resummation of the kinetic energy is necessary. Interestingly, in contrast to low-energy two-baryon processes, this resummation of baryon recoils does not lead to overall enhancement of power counting of the diagram.

    hep-phnucl-thJ.Phys.G(2019)·2 citations
15. 15*

    Gauge fixing and renormalisation scale independence of tunneling rate in abelian Higgs model and in the Standard Model

    Zygmunt Lalak🇵🇱 · Marek Lewicki🇵🇱 · Paweł Olszewski🇵🇱

    We explicitly show perturbative gauge fixing independence of the tunneling rate to a stable radiatively induced vacuum in the abelian Higgs model. We work with a class of $R_{\xi }$ gauges in the presence of both dimensionless and dimensionful gauge fixing parameters. We show that Nielsen identities survive the inclusion of higher order oparators and compute the tunnelling rate to the vacua modified by the nonrenormalisable operators in a gauge invariant manner. We also discuss implications of this method for the complete Standard Model.

    hep-phPRD(2016)·24 citations
16. 16*

    Pair production in strong SU(2) background fields

    M. R. Jia🇨🇳 · Z. L. Li🇨🇳 · C. Lv🇨🇳 · F. Wan🇨🇳 · B. S. Xie🇨🇳

    The fermion particle pair production in strong SU(2) gauged chromoelectric fields is studied by using Boltzmann-Vlasov equation in a classical way. The existence of pre-production process in a classical description is shown with the distribution evolution of non-Abelian particle production. It is interesting to find that the distribution center of particle number density is on two islands and has a split on color charge sphere as it evolutes and reaches a steady state at last, which is related to the amplitude and the varying of the field.

    hep-phFront.Phys.(Beijing)(2017)·1 citation
17. 17*

    Probing Multi-Strange Dibaryon with Proton-Omega Correlation in High-energy Heavy Ion Collisions

    Kenji Morita🇯🇵 · Akira Ohnishi🇯🇵 · Faisal Etminan🇮🇷 · Tetsuo Hatsuda🇯🇵

    Two-particle intensity correlation between the proton ($p$) and the Omega-baryon ($\Omega$) in high-energy heavy ion collisions is studied to unravel the possible spin-2 $p\Omega$ dibaryon recently suggested by lattice QCD simulations. The ratio of correlation functions between small and large collision systems, $C_{\mathrm{SL}}(Q)$, is proposed to be a new measure to extract the strong $p\Omega$ interaction without much contamination from the Coulomb attraction. Relevance of this quantity to the experimental observables in heavy-ion collisions is also discussed.

    hep-phnucl-exnucl-thPRC(2016)·98 citations
18. 18*

    Model Building with Non-Compact Cosets

    Djuna Croon🇬🇧

    We explore Goldstone boson potentials in non-compact cosets of the form SO(n,1)/SO(n). We employ a geometric approach to find the scalar potential, and focus on the conditions under which it is compact in the large field limit. We show that such a potential is found for a specific misalignment of the vacuum. This result has applications in different contexts, such as in Composite Higgs scenarios and theories for the Early Universe. We work out an example of inflation based on a non-compact coset which makes predictions which are consistent with the current observational data.

    hep-phhep-thPLB(2016)·1 citation
19. 19*

    ${\chi }_{c1}$ and ${\chi }_{c2}$ production at $e^{+}{e}^{-}$ colliders

    Henryk Czyz🇵🇱 · Johann H. Kühn🇩🇪 · Szymon Tracz🇵🇱

    Direct, resonant production of the charmonium states ${\chi }_{c1}$ and ${\chi }_{c2}$ in electron-positron annihilation is investigated. Depending on details of the model, a sizeable variation of the prediction for the production cross section is anticipated. It is demonstrated that resonant production could be observed under favorable circumstances.

    hep-phPRD(2016)·20 citations
20. 20*

    Determination of the QCD Coupling from ALEPH $\tau$ Decay Data

    Antonio Pich🇪🇸 · Antonio Rodríguez-Sánchez🇪🇸

    We present a comprehensive study of the determination of the strong coupling from $\tau$ decay, using the most recent release of the experimental ALEPH data. We critically review all theoretical strategies used in previous works and put forward various novel approaches which allow to study complementary aspects of the problem. We investigate the advantages and disadvantages of the different methods, trying to uncover their potential hidden weaknesses and test the stability of the obtained results under slight variations of the assumed inputs. We perform several determinations, using different methodologies, and find a very consistent set of results. All determinations are in excellent agreement, and allow us to extract a very reliable value for ${\alpha }_s(m_{\tau }^2)$. The main uncertainty originates in the pure perturbative error from unknown higher orders. Taking into account the systematic differences between the results obtained with the CIPT and FOPT prescriptions, we find ${\alpha }_s^{(n_f=3)}(m_{\tau }^2)=0.328\pm 0.013$ which implies ${\alpha }_s^{(n_f=5)}(M_Z^2)=0.1197\pm 0.0015$.

    hep-phhep-exPRD(2016)·135 citations
21. 21*

    Dark Matter and Leptogenesis Linked by Classical Scale Invariance

    Valentin V. Khoze🇬🇧 · Alexis D. Plascencia🇬🇧

    In this work we study a classically scale invariant extension of the Standard Model that can explain simultaneously dark matter and the baryon asymmetry in the universe. In our set-up we introduce a dark sector, namely a non-Abelian SU(2) hidden sector coupled to the SM via the Higgs portal, and a singlet sector responsible for generating Majorana masses for three right-handed sterile neutrinos. The gauge bosons of the dark sector are mass-degenerate and stable, and this makes them suitable as dark matter candidates. Our model also accounts for the matter-anti-matter asymmetry. The lepton flavour asymmetry is produced during CP-violating oscillations of the GeV-scale right-handed neutrinos, and converted to the baryon asymmetry by the electroweak sphalerons. All the characteristic scales in the model: the electro-weak, dark matter and the leptogenesis/neutrino mass scales, are generated radiatively, have a common origin and related to each other via scalar field couplings in perturbation theory.

    hep-phhep-thJHEP(2016)·57 citations
22. 22*

    Predicted value of $0\nu \beta \beta$-decay effective Majorana mass with error of lightest neutrino mass

    Shinji Maedan🇯🇵

    Assuming that the lightest neutrino mass $m_0$ is measured, we study the influence of error of the measured $m_0$ on the uncertainty of the predicted value of the neutrinoless double beta decay ($0\nu \beta \beta$) effective Majorana mass $|m_{ee}|$. The error of the predicted value of effective Majorana mass $\sigma (|m_{ee}|)$ due to the error $\sigma (m_0)$ is obtained by use of the propagation of errors. We investigate in detail how $\sigma (|m_{ee}|)$ behaves when the Majorana phases $\beta$ and $\alpha$ change, and also when the size of the lightest neutrino mass changes. It is shown that $\sigma (|m_{ee}|)$ does not exceed $\sigma (m_0)$, and that the minimum value of $\sigma (|m_{ee}|)$ in the $\beta -\alpha$ plane can be zero if the size of $m_0$ is rather small. In the normal mass ordering case, the maximum value of $\sigma (|m_{ee}|)$ in the $\beta -\alpha$ plane becomes about $0.68\sigma (m_0)$ if $m_0(=m_1)$ is very small, while in the inverted mass ordering case, it becomes about $0.02\sigma (m_0)$ if $m_0(=m_3)$ is very small. By use of the calculated $\sigma (|m_{ee}|)$, we also discuss the minimum condition for the relative error of the lightest neutrino mass to raise the possibility of obtaining the information on $\beta$ and $\alpha$.

    hep-ph1 citation
23. 23*

    Three-dimensional Statistical Jet Fragmentation

    Karoly Urmossy🇭🇺 · Zhangbu Xu🇺🇸

    We reproduce the distribution of the longitudinal and transverse components of momenta of charged hadrons stemming from jets created in proton-proton collisions at s^1/2 = 7 TeV by a statistical fragmentation model. Our hadronization model is based on microcanonical statistics and negative binomial multiplicity fluctuations. We describe the scale dependence of the fit parameters of the model with formulas obtained by approximating the exact solution of the DGLAP equation in the phi^3 theory with leading order splitting function and 1-loop coupling.

    hep-phPoS(2016)·5 citations
24. 24*

    Baryogenesis in false vacuum

    Yuta Hamada🇯🇵 · Masatoshi Yamada🇯🇵

    The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators.

    hep-phastro-ph.COhep-thEPJC(2017)·9 citations
25. 25*

    Lower and upper bounds on the mass of light quark-antiquark scalar resonance in the SVZ sum rules

    S. S. Afonin🇷🇺

    The calculation of the mass of light scalar isosinglet meson within the Shifman-Vainshtein-Zakharov (SVZ) sum rules is revisited. We develop simple analytical methods for estimation of hadron masses in the SVZ approach and try to reveal the origin of their numerical values. The calculations of hadron parameters in the SVZ sum rules are known to be heavily based on a choice of the perturbative threshold. This choice requires some important ad hoc information. We show analytically that the scalar mass under consideration has a lower and upper bound which are independent of this choice: $0.78\lesssim m_s\lesssim 1.28$ GeV.

    hep-phhep-thnucl-thInt.J.Mod.Phys.A(2016)·6 citations
26. 26*

    Simplified DM models with the full SM gauge symmetry : the case of $t$-channel colored scalar mediators

    P. Ko🇰🇷 · Alexander Natale🇰🇷 · Myeonghun Park🇰🇷 · Hiroshi Yokoya🇰🇷

    The general strategy for dark matter (DM) searches at colliders currently relies on simplified models. In this paper, we propose a new $t$-channel UV-complete simplified model that improves the existing simplified DM models in two important respects: (i) we impose the full SM gauge symmetry including the fact that the left-handed and the right-handed fermions have two independent mediators with two independent couplings, and (ii) we include the renormalization group evolution when we derive the effective Lagrangian for DM-nucleon scattering from the underlying UV complete models by integrating out the $t$-channel mediators. The first improvement will introduce a few more new parameters compared with the existing simplified DM models. In this study we look at the effect this broader set of free parameters has on direct detection and the mono-$X$ + MET ($X$=jet,$W,Z$) signatures at 13 TeV LHC while maintaining gauge invariance of the simplified model under the full SM gauge group. We find that the direct detection constraints require DM masses less than 10 GeV in order to produce phenomenologically interesting collider signatures. Additionally, for a fixed mono-W cross section it is possible to see very large differences in the mono-jet cross section when the usual simplified model assumptions are loosened and isospin violation between RH and LH DM-SM quark couplings are allowed.

    hep-phhep-exJHEP(2017)·27 citations
27. 27*

    Magnetic confinement and the Linde problem

    Yu. A. Simonov🇷🇺

    Perturbation theory of thermodynamic potentials in QCD at $T>T_c$ is considered with the nonperturbative background vacuum taken into account. It is shown that the magnetic confinement in the QCD vacuum prevents the infrared catastrophe of the perturbation theory present in the case of the free vacuum (the "Linde problem"). A short discussion is given of the applicability of the nonperturbative formalism at large $T$ and of the relation with the HTL theory.The observation of A.D.Linde, that the terms $O(g^n),n>6$ contribute to the order $O(g^6)$ is confirmed also with the account of the colormagnetic confinement, and it is shown that the latter makes these terms IR convergent, and summable. As a result one obtains the selfconsistent theory of the gluon plasma.

    hep-phhep-latphysics.atom-phPRD(2017)·24 citations
28. 28*

    A real-time lattice simulation of the thermalization of a gluon plasma: first results

    Maximilian Attems🇪🇸 · Owe Philipsen🇩🇪 · Christian Schäfer🇩🇪 · Björn Wagenbach🇩🇪 · Savvas Zafeiropoulos🇩🇪

    To achieve an understanding of the thermalization of a quark-gluon plasma, starting from QCD without using model assumptions, is a formidable task. We study the early stage dynamics of a relativistic heavy ion collision in the framework of real time simulations of classical Yang-Mills theory in a static box with the color glass condensate as initial condition. Our study generalizes a previous one by Fukushima and Gelis from SU(2) to the realistic case of SU(3). We calculate the chromo-electric and chromo-magnetic energy densities as well as the ratio of longitudinal and transverse pressure as a function of time as probes for thermalization. Our preliminary results on coarse lattices show the occurrence of Weibel instabilities prior to thermalization.

    hep-phhep-latnucl-thActa Phys.Polon.Supp.(2016)·3 citations
29. 29*

    Global Effective-Field-Theory analysis of New-Physics effects in (semi)leptonic kaon decays

    Martín González-Alonso🇫🇷 · Jorge Martin Camalich🇨🇭

    We analyze the decays $K\to \pi \ell \nu$ and $P\to \ell \nu$ ($P=K,\pi$, $\ell =e,\mu$) using a low-energy Effective-Field-Theory approach to parametrize New Physics and study the complementarity with baryon $\beta$ decays. We then provide a road map for a global analysis of the experimental data, with all the Wilson coefficients simultaneously, and perform a fit leading to numerical bounds for them and for $V_{us}$. A prominent result of our analysis is a reinterpretation of the well-known $V_{ud}-V_{us}$ diagram as a strong constraint on new physics. Finally, we reinterpret our bounds in terms of the $SU(2{)}_L\times U(1{)}_Y$-invariant operators, provide bounds to the corresponding Wilson coefficients at the TeV scale and compare our results with collider searches at the LHC.

    hep-phhep-exhep-latJHEP(2016)·124 citations
30. 30*

    A Case for Radio Galaxies as the Sources of IceCube's Astrophysical Neutrino Flux

    Dan Hooper🇺🇸

    We present an argument that radio galaxies (active galaxies with mis-aligned jets) are likely to be the primary sources of the high-energy astrophysical neutrinos observed by IceCube. In particular, if the gamma-ray emission observed from radio galaxies is generated through the interactions of cosmic-ray protons with gas, these interactions can also produce a population of neutrinos with a flux and spectral shape similar to that measured by IceCube. We present a simple physical model in which high-energy cosmic rays are confined within the volumes of radio galaxies, where they interact with gas to generate the observed diffuse fluxes of neutrinos and gamma rays. In addition to simultaneously accounting for the observations of Fermi and IceCube, radio galaxies in this model also represent an attractive class of sources for the highest energy cosmic rays.

    ↳ astro-ph.HEastro-ph.GAhep-phJCAP(2016)·54 citations
31. 31*

    Evaporation Spectrum of Black Holes from a Local Quantum Gravity Perspective

    Aurélien Barrau🇫🇷

    We revisit the hypothesis of a possible line structure in the Hawking evaporation spectrum of black holes. Because of nonperturbative quantum gravity effects, this would take place arbitrarily far away from the Planck mass. We show, based on a speculative but consistent hypothesis, that this naive prediction might in fact hold in the specific context of loop quantum gravity. A small departure from the ideal case is expected for some low-spin transitions and could allow us to distinguish several quantum gravity models. We also show that the effect is not washed out by the dynamics of the process, by existence of a mass spectrum up to a given width, or by the secondary component induced by the decay of neutral pions emitted during the time-integrated evaporation.

    ↳ gr-qcastro-ph.COhep-phhep-thPRL(2016)·5 citations
32. 32*

    Electron-positron pair creation characterized by the conversion energy

    Ibrahim.Sitiwaldi🇨🇳 · Zi-Liang Li🇨🇳 · Bai-Song Xie🇨🇳

    It is demonstrated that a pair can be characterized under which mechanism it was created according to its conversion energy, a quantity defined as the sum of electron and its conjugate positron's mass-energy, in the study of electron-positron pair creation. The value of this quantity is checked with quantum field theoretical simulations for several field configurations and found that it can describe the creation process with rich physical picture, showing all the creation channels and giving the yields of each channel specifically. Evenly as a very convenient and powerful detection quantity it can be applicable to some complicated pair creation processes such as that triggered by cooperation of two different photons as well as the dynamically assisted Schwinger mechanism.

    ↳ quant-phhep-ph0 citations
33. 33*

    The Main Results of the Borexino Experiment

    A. Derbin🇷🇺 · V. Muratova🇷🇺 · M. Agostini🇩🇪 · K. Altenmuller · S. Appel🇩🇪 · G. Bellini🇮🇹 · J. Benziger🇺🇸 · D. Bick🇩🇪 · G. Bonfini🇮🇹 · D. Bravo🇺🇸 · B. Caccianiga🇮🇹 · F. Calaprice🇺🇸 and 87 other authors

    The main physical results on the registration of solar neutrinos and the search for rare processes obtained by the Borexino collaboration to date are presented.

    ↳ hep-exhep-phphysics.ins-det7 citations
34. 34*

    Relaxion window

    Tatsuo Kobayashi🇯🇵 · Osamu Seto🇯🇵 · Takashi Shimomura🇯🇵 · Yuko Urakawa🇯🇵

    We investigate cosmological constraints on the original relaxion scenario proposed by Graham, Kaplan and Rajendran. We first discuss the appropriate sign choice of the terms in the scalar potential, when the QCD axion is the relaxion with a relaxion-inflaton coupling proposed in the original paper. We next derive the cosmologically consistent ranges of the mass and a coupling of the relaxion for both the QCD relaxion and non-QCD relaxion. The mass range is obtained by $10^{-5}$ eV $\ll m_{\varphi }\lesssim 10^4$ eV. We also find that a strong correlation between the Hubble parameter at the relaxion stabilization and the scale $\Lambda$ of non-QCD strong dynamics, which generates the non-perturbative relaxion cosine potential. For a higher relaxion mass, a large scale $\Lambda$ becomes available. However, for its lower mass, $\Lambda$ should be small and constructing such a particle physics model is challenging.

    ↳ astro-ph.COhep-phMod.Phys.Lett.A(2017)·25 citations
35. 35*

    ${\gamma }_5$ in Dimensional Regularization: a Novel Approach

    Ruggero Ferrari🇮🇹

    A new Dimensional Regularization of ${\gamma }_5$ is proposed. Cyclicity and Lorentz covariance are enforced. The extension to generic dimension is based on the integral representation of the trace of gamma's, presented in a previous paper.

    ↳ hep-thhep-lathep-phmath-ph+18 citations
36. 36*

    Measurement of Baryon Electromagnetic Form Factors at BESIII

    Cristina Morales Morales (the BESIII Collaboration)🇩🇪

    The Beijing $e^{+}{e}^{-}$-collider (BEPCII) is a double-ring symmetric collider running at center-of-mass energies between 2.0 and 4.6 GeV. This energy range allows the BESIII-experiment to measure baryon electromagnetic form factors in direct $e^{+}{e}^{-}$-annihilation and in initial state radiation processes. In this paper, results on $e^{+}{e}^{-}\to p\bar{p}$ and $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ based on data collected by BESIII in 2011 and 2012 are presented. Expectations from the BESIII high luminosity energy scan from 2015 and from radiative return at different center-of-mass energies are also reported.

    ↳ hep-exhep-ph0 citations
37. 37*

    Rare decays at LHCb

    Christoph Langenbruch (for the LHCb collaboration)🇬🇧

    Rare decays are flavour changing neutral current processes that are loop-suppressed in the Standard Model (SM). New particles in SM extensions can therefore give significant contributions, modifying branching fractions and angular distributions. Consequently, rare decays are particularly sensitive probes for New Physics (NP). These proceedings summarize the latest results from the LHCb experiment on rare decays. While most results are in good agreement with SM predictions, some tensions that recently appeared in rare semileptonic $b\to s{\ell }^{+}{\ell }^{-}$ decays are also discussed.

    ↳ hep-exhep-ph3 citations
38. 38*

    Magnetic shielding and exotic spin-dependent interactions

    D. F. Jackson Kimball🇺🇸 · J. Dudley🇺🇸 · Y. Li🇺🇸 · S. Thulasi🇺🇸 · S. Pustelny🇵🇱 · D. Budker🇩🇪 · M. Zolotorev🇺🇸

    Experiments searching for exotic spin-dependent interactions typically employ magnetic shielding between the source of the exotic field and the interrogated spins. We explore the question of what effect magnetic shielding has on detectable signals induced by exotic fields. Our general conclusion is that for common experimental geometries and conditions, magnetic shields should not significantly reduce sensitivity to exotic spin-dependent interactions, especially when the technique of comagnetometry is used. However, exotic fields that couple to electron spin can induce magnetic fields in the interior of shields made of a soft ferro- or ferrimagnetic material. This induced magnetic field must be taken into account in the interpretation of experiments searching for new spin-dependent interactions and raises the possibility of using a flux concentrator inside magnetic shields to amplify exotic spin-dependent signals.

    ↳ physics.ins-dethep-phPRD(2016)·49 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.