Thu·Jul 27, 2017Thursday·July 27, 2017

1. 01*

   Cosmology and CPT violating neutrinos

   Gabriela Barenboim🇪🇸 · Jordi Salvado🇪🇸

   The combination Charge Conjugation-Parity-Time Reversal(CPT) is a fundamental symmetry in our current understanding of nature. As such, testing CPT violation is a strongly motivated path to explore new physics. In this paper we study CPT violation in the neutrino sector, giving for the first time a bound, for a fundamental particle, in the CPT violating particle-antiparticle gravitational mass difference. We argue that cosmology is nowadays the only data sensitive to CPT violation for the neutrino-antineutrino mass splitting and we use the latest data release from Planck combined with the current Baryonic-Acoustic-Oscillation measurement to perform a full cosmological analysis. To show the potential of the future experiments we also show the results for Euclid, a next generation large scale structure experiment.

   hep-phEPJC(2017)·14 citations
2. 02*

   Subleading Corrections to Hadronic Cross-Sections at High Energies

   James D. Cockburn🇬🇧

   The Large Hadron Collider (LHC) has provided, and will continue to provide, data for collisions at the highest energies ever seen in a particle accelerator. A strong knowledge of the properties of amplitudes for Quantum Chromodynamics in the High Energy Limit is therefore important to interpret this data. We study this limit in the context of the High Energy Jets (HEJ) formalism. This formalism resums terms in the perturbative expansion of the cross-section that behave like ${\alpha }_s^n\log {\left(\frac{s}{-t}\right)}^{n-1}$, which are enhanced in this limit. Understanding this region is particularly important in certain key analyses at the LHC: for example, Higgs-boson-plus-dijet analyses where cuts are applied to pick out events with a large $m_{jj}$ and in many searches for new physics.

   hep-ph0 citations
3. 03*

   Magnetic Field Effect on Charged Scalar Pair Creation at Finite Temperature

   Gabriella Piccinelli🇲🇽 · Angel Sanchez🇲🇽

   In this work we explore the effects of a weak magnetic field and a thermal bath on the decay process of a neutral scalar boson into two charged scalar bosons. Our findings indicate that magnetic field inhibits while temperature enhances the pair production. The employed formalism allows us to isolate the contribution of magnetic fields in vacuum, leading to a separate analysis of the effects of different ingredients. This is essential since the analytical computation of the decay width necessarily needs of some approximation and the results that can be found in the literature are not always coincident. We perform the calculation in vacuum by two different weak field approximations. The particle pair production in vacuum was found to coincide with finite temperature behavior, which is opposite to results obtained by other authors in scenarios that involve neutral particles decaying into a pair of charged fermions. Among other differences between these scenarios, we traced that the analytical structure of the self-energy imposed by the spin of particles involved in the process is determinant in the behavior of the decay rate with the magnetic field.

   hep-phPRD(2017)·17 citations
4. 04*

   Heavy molecules and one-$\sigma /\omega$-exchange model

   Rui Chen🇨🇳 · Xiang Liu🇨🇳 · Atsushi Hosaka🇯🇵

   In the framework of the one-boson-exchange model, we explore whether the intermediate and short-range forces from $\sigma /\omega$-exchange can be strong enough to bind heavy molecular states. ${\Lambda }_{c}D(\bar{D})$, and ${\Lambda }_c{\Lambda }_c({\bar{\Lambda }}_c)$ systems have been studied and compared. We find that the force from $\sigma$-exchange is attractive and dominant, whereas the $\omega$-exchange force not. As a consequence, the S-wave ${\Lambda }_{c}D$, ${\Lambda }_c{\Lambda }_c$, and ${\Lambda }_c{\bar{\Lambda }}_c$ can be possible molecular candidates. We further indicate that one hadron-hadron system with more light quarks $(u,d)$ can be easier to form a bound state. As a byproduct, by studying the heavy-quark mass dependence for the ${\Lambda }_{c}D(\bar{D})$-like and ${\Lambda }_c{\Lambda }_c({\bar{\Lambda }}_c)$-like systems, we find that the charm/bottom sector can easily accommodates molecular states. Finally, the ${\Lambda }_{c}N(\bar{N})$ and ${\Lambda }_{b}N(\bar{N})$ systems are investigated. Our results indicate that they are also likely to form bound states. By including one-$\pi$-exchange forces providing additional attraction when coupled channels are included, we expect many molecular states in heavy quark sectors.

   hep-phPRD(2017)·71 citations
5. 05*

   Four-Loop Non-Singlet Splitting Functions in the Planar Limit and Beyond

   S. Moch (1)🇩🇪 · B. Ruijl🇳🇱 · T. Ueda🇳🇱 · J.A.M. Vermaseren (2)🇳🇱 · A. Vogt (3) ((1) Hamburg U., (2) NIKHEF, Amsterdam, (3) Liverpool U.)🇬🇧

   We present the next-to-next-to-next-to-leading order (N^3LO) contributions to the non-singlet splitting functions for both parton distribution and fragmentation functions in perturbative QCD. The exact expressions are derived for the terms contributing in the limit of a large number of colours. For the remaining contributions, approximations are provided that are sufficient for all collider-physics applications. From their threshold limits we derive analytical and high-accuracy numerical results, respectively, for all contributions to the four-loop cusp anomalous dimension for quarks, including the terms proportional to quartic Casimir operators. We briefly illustrate the numerical size of the four-loop corrections, and the remarkable renormalization-scale stability of the N^3LO results, for the evolution of the non-singlet parton distribution and the fragmentation functions. Our results appear to provide a first point of contact of four-loop QCD calculations and the so-called wrapping corrections to anomalous dimensions in N=4 super Yang-Mills theory.

   hep-phhep-thJHEP(2017)·294 citations
6. 06*

   Double-parton scattering effects in associated production of charm mesons and dijets at the LHC

   Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

   We calculate several differential distributions for the production of charm and dijets. Both single-parton scattering (SPS) and double-parton scattering (DPS) contributions are calculated in the $k_T$-factorization approach. The Kimber-Martin-Ryskin unintegrated parton distributions are used in our calculations. Relatively low cuts on jet transverse momenta are imposed to enhance the double-parton scattering mechanism contribution. We find dominance of the DPS contribution over the SPS one. We have found regions of the phase space where the SPS contribution is negligible compared to the DPS contribution. The distribution in transverse momentum of charm quark/antiquark or charmed mesons can be used to observe transition from the dominance of DPS at low transvsverse momenta to the dominance of SPS at large transverse momenta. Very distinct azimuthal correlation patterns (for $c\bar{c}$, $c\text{-jet}$, $\text{jet-jet}$, $D^0\text{-jet}$, $D^0{D}^0$) are predicted as a result of the competition of the SPS and DPS mechanisms.

   hep-phhep-exPRD(2017)·15 citations
7. 07*

   Non-extensive Fokker-Planck transport coefficients of heavy quarks

   Trambak Bhattacharyya🇿🇦 · Jean Cleymans🇿🇦

   In presence of the non-ideal plasma effects, Heavy Quarks (HQs) carry out non linear random walk inside Quark-Gluon Plasma (QGP) and in the small momentum transfer limit, the evolution of the HQ distribution is dictated by the Non Linear Fokker-Planck Equation (NLFPE). Using the NLFPE, we calculate the transport coefficients (drag and diffusion) of heavy quarks travelling through QGP. We observe substantial modification in the momentum and temperature variation of the transport coefficients; and this will modify the physical picture we are having about the transport of heavy quarks inside QGP, and hence, about the characterisation of the plasma.

   hep-phnucl-th3 citations
8. 08*

   On a possibility of baryonic exotica

   Michal Praszalowicz🇵🇱

   Models based on chiral symmetry predict pentaquarks that have relatively low masses. We briefly review both theoretical and experimental status of exotica in the light sector. Next, shall show how to extend chiral models to baryons with one heavy quark and show that one expects exotica also in this case. Finally, we interpret recently discovered by the LHCb collaboration five ${\Omega }_c^{\ast }$ resonances in terms of regular and exotic excitations of the ground state ${\Omega }_c$.

   hep-phActa Phys.Polon.B(2017)·2 citations
9. 09*

   Sharp spectral features from light dark matter decay via gravity portals

   Oscar Catà🇩🇪 · Alejandro Ibarra🇩🇪 · Sebastian Ingenhütt🇩🇪

   We investigate the phenomenology of dark matter decay assuming that it is induced by non-minimal coupling to gravity, when the dark matter mass is in the sub-GeV range, i.e. below the QCD confinement scale. We show that the decay of the singlet scalar dark matter candidate produces sharp features in the photon spectrum, in the form of lines, boxes, and also in the form of a novel spectral feature, characterized by the decay into $e^{+}{e}^{-}\gamma$ through a contact interaction, with decay branching fractions depending only on a single parameter, namely the dark matter mass. We also derive upper limits on the strength of the gravity portal from the non-observation of sharp features in the isotropic diffuse gamma-ray spectra measured by COMPTEL, EGRET and Fermi-LAT, and the X-ray spectrum measured by INTEGRAL. Finally, we briefly comment on the impact of dark matter decay via non-minimal coupling to gravity on the reionization history of the Universe.

   hep-phJCAP(2017)·11 citations
10. 10*

    Simultaneous Search for Extra Light and Heavy Higgs Bosons via Cascade Decays

    Ulrich Ellwanger🇫🇷 · Matias Rodriguez-Vazquez🇫🇷

    Models with extended Higgs sectors can contain several additional Higgs states, heavier or lighter than the SM Higgs boson. The couplings of lighter extra states to SM particles can be strongly reduced, leading to small cross sections for their direct production. Heavier extra states can have larger couplings to SM particles and, moreover, have large branching fractions into lighter extra states, notably into a SM-like Higgs boson accompagnied by another Higgs state which can be lighter or heavier than 125$\sim$GeV. Motivated by corresponding scenarios in the NMSSM we study the prospects for the discovery or exclusion of cascade decays $ggF\to H_3\to H_2+H_1$ in the $b\bar{b}b\bar{b}$, $b\bar{b}\tau \tau$ and $b\bar{b}\gamma \gamma$ final states where either $H_1$ or $H_2$ can be SM-like. Significant regions of the NMSSM parameter space can be tested by these searches. These are, however, not confined to models of the NMSSM type.

    hep-phhep-exJHEP(2017)·41 citations
11. 11*

    Hydrodynamical corrections to electromagnetic emissivities in QCD

    Yizhuang Liu🇺🇸 · Ismail Zahed🇺🇸

    We provide a general framework for the derivation of the hydrodynamical corrections to the QCD electromagnetic emissivities in a viscous fluid. Assuming that the emission times are short in comparison to the fluid evolution time, we show that the leading corrections in the fluid gradients are controlled by the bulk and shear tensors times pertinent response functions involving the energy-momentum tensor. In a hadronic fluid phase, we explicit these contributions using spectral functions. Using the vector dominance approximation, we show that the bulk viscosity correction to the photon rate is sizable, while the shear viscosity is negligible for about all frequencies. In the partonic phase near the transition temperature we provide an assessment of the viscous corrections to the photon and dilepton emissions, using a non-perturbative quark-gluon plasma with soft thermal gluonic corrections in the form of operators of leading mass dimension. Again, the thermal bulk viscosity corrections are found to be larger than the thermal shear viscosity corrections at all energies for both the photon and dilepton in the partonic phase.

    hep-phhep-thnucl-thPRD(2017)·6 citations
12. 12*

    Dynamic Universality Class of Model H with Frustrated Diffusion: $ϵ$-Expansion

    Ho-Ung Yee🇺🇸

    We study a variation of the dynamic universality class of model H in a spatial dimension of $d=4-ϵ$, by frustrating charge diffusion and momentum density fluctuations along $d_T=1$ or $d_T=2$ dimensions, while keeping the same dynamics of model H in the other $d_L=d-d_T$ dimensions. The case of $d_T=2$ describes the QCD critical point in a background magnetic field. We find that these models belong to a different dynamical universality class due to extended conservation laws compared to the model H, although the static universality class remains the same as the 3-dimensional Ising model. We compute the dynamic critical exponents of these models in first order of $ϵ$-expansion to find that $x_{\lambda }\approx 0.847ϵ$, $x_{\bar{\eta }}\approx 0.153ϵ$, and $z=4-x_{\lambda }\approx 3.15$ when $ϵ=1$ and $d_T=2$. For $d_T=1$ the results are numerically similar to the model H values: $z\approx 3.08$.

    hep-phhep-thnucl-thPRD(2018)·3 citations
13. 13*

    Exploring light mediators with low-threshold direct detection experiments

    Felix Kahlhoefer🇩🇪 · Suchita Kulkarni🇦🇹 · Sebastian Wild🇩🇪

    We explore the potential of future cryogenic direct detection experiments to determine the properties of the mediator that communicates the interactions between dark matter and nuclei. Due to their low thresholds and large exposures, experiments like CRESST-III, SuperCDMS SNOLAB and EDELWEISS-III will have excellent capability to reconstruct mediator masses in the MeV range for a large class of models. Combining the information from several experiments further improves the parameter reconstruction, even when taking into account additional nuisance parameters related to background uncertainties and the dark matter velocity distribution. These observations may offer the intriguing possibility of studying dark matter self-interactions with direct detection experiments.

    hep-phastro-ph.COhep-exJCAP(2017)·40 citations
14. 14*

    Double Bangs from New Physics in IceCube

    Pilar Coloma🇺🇸 · Pedro A. N. Machado🇺🇸 · Ivan Martinez-Soler🇪🇸 · Ian M. Shoemaker🇺🇸

    A variety of new physics models allows for neutrinos to up-scatter into heavier states. If the incident neutrino is energetic enough, the heavy neutrino may travel some distance before decaying. In this work, we consider the atmospheric neutrino flux as a source of such events. At IceCube, this would lead to a "double-bang" (DB) event topology, similar to what is predicted to occur for tau neutrinos at ultra-high energies. The DB event topology has an extremely low background rate from coincident atmospheric cascades, making this a distinctive signature of new physics. Our results indicate that IceCube should already be able to derive new competitive constraints on models with GeV-scale sterile neutrinos using existing data.

    hep-phastro-ph.HEhep-exPRL(2017)·138 citations
15. 15*

    Consistency relations in multi-field inflation

    Jinn-Ouk Gong🇰🇷 · Min-Seok Seo🇰🇷

    We study the consequences of spatial coordinate transformation in multi-field inflation. Among the spontaneously broken de Sitter isometries, only dilatation in the comoving gauge preserves the form of the metric and thus results in quantum-protected Slavnov-Taylor identities. We derive the corresponding consistency relations between correlation functions of cosmological perturbations in two different ways, by the connected and one-particle-irreducible Green's functions. The lowest-order consistency relations are explicitly given, and we find that even in multi-field inflation the consistency relations in the soft limit are independent of the detail of the matter sector.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2018)·9 citations
16. 16*

    Constraining the equation of state with identified particle spectra

    Akihiko Monnai🇫🇷 · Jean-Yves Ollitrault🇫🇷

    We show that in a central nucleus-nucleus collision, the variation of the mean transverse mass with the multiplicity is determined, up to a rescaling, by the variation of the energy over entropy ratio as a function of the entropy density, thus providing a direct link between experimental data and the equation of state. Each colliding energy thus probes the equation of state at an effective entropy density, whose approximate value is $19$ fm${}^{-3}$ for Au+Au collisions at 200 GeV and $41$ fm${}^{-3}$ for Pb+Pb collisions at 2.76 TeV, corresponding to temperatures of $227$ MeV and $279$ MeV if the equation of state is taken from lattice calculations. The relative change of the mean transverse mass as a function of the colliding energy gives a direct measure of the pressure over energy density ratio $P/ϵ$, at the corresponding effective density. Using RHIC and LHC data, we obtain $P/ϵ=0.21\pm 0.10$, in agreement with the lattice value $P/ϵ=0.23$ in the corresponding temperature range. Measurements over a wide range of colliding energies using a single detector with good particle identification would help reducing the error.

    ↳ nucl-thhep-lathep-phnucl-exPRC(2017)·17 citations
17. 17*

    Axion as a cold dark matter candidate: Proof to fully nonlinear order

    Hyerim Noh🇰🇷 · Jai-chan Hwang🇰🇷 · Chan-Gyung Park🇰🇷

    We present a proof of the axion as a cold dark matter candidate to the fully nonlinear order perturbations based on Einstein's gravity. We consider the axion as a coherently oscillating massive classical scalar field without interaction. We present the fully nonlinear and exact, except for {\it ignoring} the transverse-tracefree tensor-type perturbation, hydrodynamic equations for an axion fluid in Einstein's gravity. We show that the axion has the characteristic pressure and anisotropic stress, the latter starts to appear from the second-order perturbation. But these terms do not directly affect the hydrodynamic equations in our axion treatment. Instead, what behaves as the effective pressure term in relativistic hydrodynamic equations is the perturbed lapse function and the relativistic result coincides exactly with the one known in the previous non-relativistic studies. The effective pressure term leads to a Jeans scale which is of the solar-system scale for conventional axion mass. As the fully nonlinear and relativistic hydrodynamic equations for an axion fluid coincide exactly with the ones of a zero-pressure fluid in the super-Jeans scale, we have proved the cold dark matter nature of such an axion in that scale.

    ↳ gr-qchep-phhep-thApJ(2017)·28 citations
18. 18*

    Black Hole Evaporation, Quantum Hair and Supertranslations

    Cesar Gomez🇪🇸 · Sebastian Zell🇩🇪

    In a black hole, hair and quantum information retrieval are interrelated phenomena. The existence of any new form of hair necessarily implies the existence of features in the quantum-mechanically evaporated radiation. Classical supertranslation hair can be only distinguished from global diffeomorphisms if we have access to the interior of the black hole. Indirect information on the interior can only be obtained from the features of the quantum evaporation. Supertranslations $(T^{-},T^{+})\in BM{S}_{-}\otimes BM{S}_{+}$ can be used as bookkepers of the probability distributions of the emitted quanta where the first element describes the classical injection of energy and the second one is associated to quantum-mechanical emission. The connection between $T^{-}$ and $T^{+}$ is determined by the interior quantum dynamics of the black hole. We argue that restricting to the diagonal subgroup is only possible for decoupled modes, which do not bring any non-trivial information about the black hole interior and therefore do not constitute physical hair. We show that this is also true for gravitational systems without horizon, for which both injection and emission can be described classically. Moreover, we discuss and clarify the role of infrared physics in purification.

    ↳ hep-thgr-qchep-phquant-phEPJC(2018)·19 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.