Mon·Feb 13, 2017Monday·February 13, 2017

1. 01*

   Decay photons from the ALP burst of type-II supernovae

   J. Jaeckel🇩🇪 · P.C. Malta🇧🇷 · J. Redondo🇪🇸

   We determine limits from SN 1987A on massive axion-like particles (ALPs) with masses in the 10 keV - 100 MeV range and purely coupled to two photons. ALPs produced in the core collapse escape from the star and decay into photons that can be observed as a delayed and diffuse burst. We discuss the time and angular distribution of such a signal. Looking into the future we also estimate the possible improvements if the red supergiant Betelgeuse explodes in a supernova event.

   hep-phastro-ph.HEPRD(2018)·192 citations
2. 02*

   TVID: Three-loop Vacuum Integrals from Dispersion relations

   S. Bauberger🇩🇪 · A. Freitas🇺🇸

   TVID is a program for the numerical evaluation of general three-loop vacuum integrals with arbitrary masses. It consists of two parts. An algebraic module, implemented in Mathematica, performs the separation of the divergent pieces of the master integrals and identifies special cases. The numerical module, implemented in C, carries out the numerical integration of the finite pieces. In this note, the structure of the program is explained and a few usage examples are given.

   hep-ph22 citations
3. 03*

   Renormalisation-group improved analysis of $\mu \to e$ processes in a systematic effective-field-theory approach

   Andreas Crivellin🇨🇭 · Sacha Davidson🇫🇷 · Giovanni Marco Pruna🇨🇭 · Adrian Signer🇨🇭

   In this article, a complete analysis of the three muonic lepton-flavour violating processes $\mu \to e\gamma$, $\mu \to 3e$ and coherent nuclear $\mu \to e$ conversion is performed in the framework of an effective theory with dimension six operators defined below the electroweak symmetry breaking scale $m_W$. The renormalisation-group evolution of the Wilson coefficients between $m_W$ and the experimental scale is fully taken into account at the leading order in QCD and QED, and explicit analytic and numerical evolution matrices are given. As a result, muonic decay and conversion rates are interpreted as functions of the Wilson coefficients at any scale up to $m_W$. Taking the experimental limits on these processes as input, the phenomenology of the mixing effects is investigated. It is found that a considerable set of Wilson coefficients unbounded in the simplistic tree-level approach are instead severely constrained. In addition, correlations among operators are studied both in the light of current data and future experimental prospects.

   hep-phJHEP(2017)·176 citations
4. 04*

   XYZ mesons and Glueballs: effects of the quark-gluon mixing

   Nikolai Kochelev🇷🇺

   We present the new developments in the physics of XYZ mesons and glueballs and discuss the connection between properties of the $XYZ$ mesons and glueballs, and the structure of the QCD vacuum. It is shown that the mixing between quark and gluon degree of freedoms induced by the nontrivial topological structure of the QCD vacuum might affect strongly the properties of the exotic hadrons. A new interpretation of the $XYZ$ mesons as the mixing between radial excitations of light quark-antiquark systems and states with heavy quark content is suggested. We introduce also a new mechanism of quarkonia production in hadron-hadron collisions coming from the mixing of light and heavy quark sectors of QCD. This mechanism is based on the nontrivial topological structure of the QCD vacuum and might explain the polarization puzzle in inclusive $J/\Psi$ production in high energy reactions. The possibility of big changes of the scalar and pseudoscalar glueball masses in the hot gluonic plasma is established and their consequences in the phase structure of QCD analyzed.

   hep-ph0 citations
5. 05*

   Estimating nonlinear effects in forward dijet production in ultra-peripheral heavy ion collisions at the LHC

   P. Kotko🇺🇸 · K. Kutak🇵🇱 · S. Sapeta🇵🇱 · A. M. Stasto🇺🇸 · M. Strikman🇺🇸

   Using the framework that interpolates between the leading power limit of the Color Glass Condensate and the High Energy (or $k_T$) factorization we calculate the direct component of the forward dijet production in ultra-peripheral $\mathrm{Pb}$-$\mathrm{Pb}$ collisions at CM energy $5.1\mathrm{TeV}$ per nucleon pair. The formalism is applicable when the average transverse momentum of the dijet system $P_T$ is much bigger than the saturation scale $Q_s$, $P_T\gg Q_s$, while the imbalance of the dijet system can be arbitrary. The cross section is uniquely sensitive to the Weizsäcker-Williams (WW) unintegrated gluon distribution, which is far less known from experimental data than the most common dipole gluon distribution appearing in inclusive small-$x$ processes. We have calculated cross sections and nuclear modification ratios using WW gluon distribution obtained from the dipole gluon density through the Gaussian approximation. The dipole gluon distribution used to get WW was fitted to the inclusive HERA data with the nonlinear extension of unified BFKL+DGLAP evolution equation. The saturation effects are visible but rather weak for realistic $p_T$ cut on the dijet system, reaching about $20\%$ with the cut as low as $6\mathrm{GeV}$. We find that the LO collinear factorization with nuclear leading twist shadowing predicts quite similar effects.

   hep-phhep-exEPJC(2017)·61 citations
6. 06*

   Probing atmospheric mixing and leptonic CP violation in current and future long baseline oscillation experiments

   Sabya Sachi Chatterjee🇮🇳 · Pedro Pasquini🇧🇷 · J.W.F. Valle🇪🇸

   We perform realistic simulations of the current and future long baseline experiments such as T2K, NO$\nu$A, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle ${\theta }_{23}$ as well as the value and sign of the CP phase ${\delta }_{CP}$.

   hep-phhep-exPLB(2017)·27 citations
7. 07*

   Vacuum Cherenkov radiation for Lorentz-violating fermions

   M. Schreck🇧🇷

   The current work focuses on the process of vacuum Cherenkov radiation for Lorentz-violating fermions that are described by the minimal Standard-Model Extension (SME). To date, most considerations of this important hypothetical process have been restricted to Lorentz-violating photons, as the necessary theoretical tools for the SME fermion sector have not been available. With their development in a very recent paper, we are now in a position to compute the decay rates based on a modified Dirac theory. Two realizations of the Cherenkov process are studied. In the first scenario, the spin projection of the incoming fermion is assumed to be conserved, and in the second, the spin projection is allowed to flip. The first type of process is shown to be still forbidden for the dimensionful $a$ and $b$ coefficients where there are strong indications that it is energetically disallowed for the $H$ coefficients, as well. However, it is rendered possible for the dimensionless $c$, $d$, $e$, $f$, and $g$ coefficients. For large initial fermion energies, the decay rates for the $c$ and $d$ coefficients were found to grow linearly with momentum and to be linearly suppressed by the smallness of the Lorentz-violating coefficient where for the $e$, $f$, and $g$ coefficients this suppression is even quadratic. The decay rates vanish in the vicinity of the threshold, as expected. The decay including a fermion spin flip plays a role for the spin-nondegenerate operators and it was found to occur for the dimensionful $b$ and $H$ coefficients as well as for the dimensionless $d$ and $g$. The characteristics of this process differ much from the properties of the spin-conserving one, e.g., there is no threshold. Based on experimental data of ultra-high-energy cosmic rays, new constraints on Lorentz violation in the quark sector are obtained from the thresholds.

   hep-phhep-thPRD(2017)·54 citations
8. 08*

   ${\alpha }_s$ from hadron multiplicities via SUSY-like relation between anomalous dimensions

   Bernd A. Kniehl🇺🇸 · Anatoly V. Kotikov🇷🇺

   We recover in QCD an amazingly simple relationship between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations for the first Mellin moments $D_{q,g}({\mu }^2)$ of the quark and gluon fragmentation functions, which correspond to the average hadron multiplicities in jets initiated by quarks and gluons, respectively. This relationship, which is independent of the number of quark flavors, dramatically improves previous treatments by allowing for an exact solution of the evolution equations. So far, such relationships have only been known from supersymmetric QCD, where $C_F/C_A=1$. This also allows us to extend our knowledge of the ratio $D_g^{-}({\mu }^2)/D_q^{-}({\mu }^2)$ of the minus components by one order in $\sqrt{{\alpha }_s}$. Exploiting available next-to-next-to-next-to-leading-order information on the ratio $D_g^{+}({\mu }^2)/D_q^{+}({\mu }^2)$ of the dominant plus components, we fit the world data of $D_{q,g}({\mu }^2)$ for charged hadrons measured in $e^{+}{e}^{-}$ annihilation to obtain ${\alpha }_s^{(5)}(M_Z)=0.1205\genfrac{}{}{0ex}{}{+0.016}{-0.0020}$.

   hep-phhep-exhep-th6 citations
9. 09*

   The Many Guises of a Neutral Fermion Singlet

   Ernest Ma (UC Riverside)🇺🇸

   The addition of a neutral fermion singlet to the standard model of particle interactions leads to many diverse possibilities. It is not necessarily a right-handed neutrino. I discuss many of the simplest and most interesting scenarios of possible new physics with this approach. In particular I propose the possible spontaneous breaking of baryon number, resulting in the massless 'sakharon'.

   hep-phMod.Phys.Lett.A(2017)·10 citations
10. 10*

    The ALP miracle: unified inflaton and dark matter

    Ryuji Daido🇯🇵 · Fuminobu Takahashi🇯🇵 · Wen Yin🇨🇳

    We propose a scenario where both inflation and dark matter are described by a single axion-like particle (ALP) in a unified manner. In a class of the minimal axion hilltop inflation, the effective masses at the maximum and mimimum of the potential have equal magnitude but opposite sign, so that the ALP inflaton is light both during inflation and in the true vacuum. After inflation, most of the ALPs decay and evaporate into plasma through a coupling to photons, and the remaining ones become dark matter. We find that the observed CMB and matter power spectrum as well as the dark matter abundance point to an ALP of mass $m_{\varphi }=\mathcal{O}(0.01)$ eV and the axion-photon coupling $g_{\varphi \gamma \gamma }=\mathcal{O}(10^{-11})$GeV${}^{-1}$: the ALP miracle. The suggested parameter region is within the reach of the next generation axion helioscope, IAXO. Furthermore, thermalized ALPs contribute to hot dark matter and its abundance is given in terms of the effective number of extra neutrino species, $\Delta N_{\mathrm{eff}}\simeq 0.03$, which can be tested by the future CMB experiments. We also discuss a case with multiple ALPs, where the coupling to photons can be enhanced in the early Universe by an order of magnitude or more, which enlarges the parameter space for the ALP miracle. The heavy ALP plays a role of the waterfall field in hybrid inflation, and reheats the Universe, and it can be searched for in various experiments such as SHiP.

    hep-phastro-ph.COhep-exhep-thJCAP(2017)·169 citations
11. 11*

    $J/\psi$ production and polarization within a jet

    Zhong-Bo Kang🇺🇸 · Jian-Wei Qiu🇺🇸 · Felix Ringer🇺🇸 · Hongxi Xing🇺🇸 · Hong Zhang🇺🇸

    We study the production and polarization of $J/\psi$ mesons within a jet in proton-proton collisions at the LHC. We define the $J/\psi$-jet fragmentation function as a ratio of differential jet cross sections with and without the reconstructed $J/\psi$ in the jet. We demonstrate that this is a very useful observable to help explore the $J/\psi$ production mechanism, and to differentiate between different NRQCD global fits based on inclusive $J/\psi$ cross sections. Furthermore, we propose to measure the polarization of $J/\psi$ mesons inside the jet, which can provide even more stringent constraints for the heavy quarkonium production mechanism.

    hep-phhep-exPRL(2017)·55 citations
12. 12*

    The fully differential top decay distribution

    J.A. Aguilar-Saavedra🇪🇸 · J. Boudreau🇺🇸 · C. Escobar🇪🇸 · J. Mueller🇺🇸

    We write down the four-dimensional fully differential decay distribution for the top quark decay $t\to Wb\to \ell \nu b$. We discuss how its eight physical parameters can be measured, either with a global fit or with the use of selected one-dimensional distributions and asymmetries. We give expressions for the top decay amplitudes for a general $tbW$ interaction, and show how the untangled measurement of the two components of the fraction of longitudinal $W$ bosons - those with $b$ quark helicities of $1/2$ and $-1/2$, respectively - could improve the precision of a global fit to the $tbW$ vertex.

    hep-phhep-exEPJC(2017)·18 citations
13. 13*

    The non-perturbative structure of the photon and gluon propagators

    Peter Lowdon🇺🇸

    The non-perturbative structure of the photon and gluon propagators plays an important role in governing the dynamics of quantum electrodynamics (QED) and quantum chromodynamics (QCD) respectively. Although it is often assumed that these interacting field propagators can be decomposed into longitudinal and transverse components, as for the free case, it turns out that in general this is not possible. Moreover, the non-abelian gauge symmetry of QCD permits the momentum space gluon propagator to contain additional singular terms involving derivatives of $\delta (p)$, the appearance of which is related to confinement. Despite the possibility of the failure of the transverse-longitudinal decomposition for the photon and gluon propagators, and the appearance of singular terms in the gluon propagator, the Slavnov-Taylor identity nevertheless remains preserved.

    ↳ hep-thhep-lathep-phPRD(2017)·31 citations
14. 14*

    Effective mixing between clouds of different species of particles that are massless, or nearly massless

    R. F. Sawyer🇺🇸

    In collisions of intense beams, or clouds, coherent dynamics open the way for fast transformations of light highly relativistic species into one another. Possible applications are suggested for situations, each involving two out of three of: photons, neutrinos, or gravitons.

    ↳ quant-phhep-ph2 citations
15. 15*

    Cuts from residues: the one-loop case

    Samuel Abreu🇩🇪 · Ruth Britto🇮🇪 · Claude Duhr🇨🇭 · Einan Gardi🇬🇧

    Using the multivariate residue calculus of Leray, we give a precise definition of the notion of a cut Feynman integral in dimensional regularization, as a residue evaluated on the variety where some of the propagators are put on shell. These are naturally associated to Landau singularities of the first type. Focusing on the one-loop case, we give an explicit parametrization to compute such cut integrals, with which we study some of their properties and list explicit results for maximal and next-to-maximal cuts. By analyzing homology groups, we show that cut integrals associated to Landau singularities of the second type are specific combinations of the usual cut integrals, and we obtain linear relations among different cuts of the same integral. We also show that all one-loop Feynman integrals and their cuts belong to the same class of functions, which can be written as parametric integrals.

    ↳ hep-thhep-phJHEP(2017)·111 citations
16. 16*

    What is modified gravity and how to differentiate it from particle dark matter?

    Xavier Calmet🇬🇧 · Iberê Kuntz🇬🇧

    An obvious criterion to classify theories of modified gravity is to identify their gravitational degrees of freedom and their coupling to the metric and the matter sector. Using this simple idea, we show that any theory which depends on the curvature invariants is equivalent to general relativity in the presence of new fields that are gravitationally coupled to the energy-momentum tensor. We show that they can be shifted into a new energy-momentum tensor. There is no a priori reason to identify these new fields as gravitational degrees of freedom or matter fields. This leads to an equivalence between dark matter particles gravitationally coupled to the standard model fields and modified gravity theories designed to account for the dark matter phenomenon. Due to this ambiguity, it is impossible to differentiate experimentally between these theories and any attempt of doing so should be classified as a mere interpretation of the same phenomenon.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2017)·37 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.