Fri·Sep 22, 2017Friday·September 22, 2017

1. 01*

   The Minimal Flavour Violating Axion

   F. Arias-Aragon🇪🇸 · L. Merlo🇪🇸

   The solution to the Strong CP problem is analysed within the Minimal Flavour Violation (MFV) context. An Abelian factor of the complete flavour symmetry of the fermionic kinetic terms may play the role of the Peccei-Quinn symmetry in traditional axion models. Its spontaneous breaking, due to the addition of a complex scalar field to the Standard Model scalar spectrum, generates the MFV axion, which may redefine away the QCD theta parameter. It differs from the traditional QCD axion for its couplings that are governed by the fermion charges under the axial Abelian symmetry. It is also distinct from the so-called Axiflavon, as the MFV axion does not describe flavour violation, while it does induce flavour non-universality effects. The MFV axion phenomenology is discussed considering astrophysical, collider and flavour data.

   hep-phJHEP(2017)·93 citations
2. 02*

   Methods for deriving functional equations for Feynman integrals

   O. V. Tarasov🇷🇺

   We present short review of two methods for obtaining functional equations for Feynman integrals. Application of these methods for finding functional equations for one- and two- loop integrals is described in detail. It is shown that with the aid of functional equations Feynman integrals in general kinematics can be expressed in terms of simpler integrals. Similarities between functional equations for Feynman integrals and addition theorem for Abel integrals are shortly discussed.

   hep-phJ.Phys.Conf.Ser.(2017)·6 citations
3. 03*

   Axion as a non-WIMP dark matter candidate

   Ken'ichi Saikawa🇩🇪

   The axion arises in well-motivated extensions of the Standard Model of particle physics and is regarded as an alternative to the weakly interacting massive particle paradigm to explain the nature of dark matter. In this contribution, we review theoretical aspects of dark matter axions, particularly focusing on recent developments in the estimation of their relic abundance. A closer look at their non-thermal production mechanisms in the early universe reveals the possibility of explaining the observed dark matter abundance in various mass ranges. The mass ranges predicted in various cosmological scenarios are briefly summarized.

   hep-phastro-ph.COPoS(2017)·12 citations
4. 04*

   LHC limits on axion-like particles from heavy-ion collisions

   Simon Knapen🇺🇸 · Tongyan Lin🇺🇸 · Hou Keong Lou🇺🇸 · Tom Melia🇯🇵

   In these proceedings we use recent LHC heavy-ion data to set a limit on axion-like particles coupling to electromagnetism with mass in the range 10-100 GeV. We recast ATLAS data as per the strategy proposed in 1607.06083, and find results in-line with the projections given there.

   hep-phhep-exCERN Proc.(2018)·38 citations
5. 05*

   The $B\to \pi K$ Puzzle Revisited

   Nicolas Boisvert Beaudry🇨🇦 · Alakabha Datta🇺🇸 · David London🇨🇦 · Ahmed Rashed🇺🇸 · Jean-Samuel Roux🇨🇦

   For a number of years, there has been a certain inconsistency among the measurements of the branching ratios and CP asymmetries of the four $B\to \pi K$ decays ($B^{+}\to {\pi }^{+}{K}^0$, $B^{+}\to {\pi }^0{K}^{+}$, $B^0\to {\pi }^{-}{K}^{+}$, $B^0\to {\pi }^0{K}^0$). In this paper, we re-examine this $B\to \pi K$ puzzle. We find that the key unknown parameter is $|C^{\prime }/T^{\prime }|$, the ratio of color-suppressed and color-allowed tree amplitudes. If this ratio is large, $|C^{\prime }/T^{\prime }|=0.5$, the SM can explain the data. But if it is small, $|C^{\prime }/T^{\prime }|=0.2$, the SM cannot explain the $B\to \pi K$ puzzle -- new physics (NP) is needed. The two types of NP that can contribute to $B\to \pi K$ at tree level are $Z^{\prime }$ bosons and diquarks. $Z^{\prime }$ models can explain the puzzle if the $Z^{\prime }$ couples to right-handed $u\bar{u}$ and/or $d\bar{d}$, with $g_R^{dd}\ne g_R^{uu}$. Interestingly, half of the many $Z^{\prime }$ models proposed to explain the present anomalies in $b\to s{\mu }^{+}{\mu }^{-}$ decays have the required $Z^{\prime }$ couplings to $u\bar{u}$ and/or $d\bar{d}$. Such models could potentially explain both the $b\to s{\mu }^{+}{\mu }^{-}$ anomalies and the $B\to \pi K$ puzzle. The addition of a color sextet diquark that couples to $ud$ can also explain the puzzle.

   hep-phhep-exJHEP(2018)·50 citations
6. 06*

   Regge-like relation and a universal description of heavy-light systems

   Kan Chen🇨🇳 · Yubing Dong🇨🇳 · Xiang Liu🇨🇳 · Qi-Fang Lü🇨🇳 · Takayuki Matsuki🇯🇵

   Using the Regge-like formula $(M-m_Q{)}^2=\pi \sigma L$ between hadron mass $M$ and angular momentum $L$ with a heavy quark mass $m_Q$ and a string tension $\sigma$, we analyze all the heavy-light systems, i.e., $D/D_s/B/B_s$ mesons and charmed and bottom baryons.Numerical plots are obtained for all the heavy-light mesons of experimental data whose slope becomes nearly equal to 1/2 of that for light hadrons. Assuming that charmed and bottom baryons consist of one heavy quark and one light cluster of two light quarks (diquark), we apply the formula to all the heavy-light baryons including recently discovered ${\Omega }_c$'s and find that these baryons experimentally measured satisfy the above formula. We predict the average mass values of $B$, $B_s$, ${\Lambda }_b$, ${\Sigma }_c$, ${\Xi }_c$, and ${\Omega }_c$ with $L=2$ as 6.01, 6.13, 6.15, 3.05, 3.07, and 3.34 GeV, respectively. Our results on baryons suggest that these baryons can be safely regarded as heavy quark-light cluster configuration. We also find a universal description for all the heavy-light mesons as well as baryons, i.e., one unique line is enough to describe both of charmed and bottom heavy-light systems. Our results suggest that instead of mass itself, gluon flux energy is essential to obtain a linear trajectory.

   hep-phhep-exEPJC(2018)·30 citations
7. 07*

   Implication of Quadratic Divergences Cancellation in the Two Higgs Doublet Model

   Neda Darvishi🇵🇱 · Maria Krawczyk🇵🇱

   With the aim of exploring the Higgs sector of the Two Higgs Doublet Model (2HDM), we have chosen the exact and soft $Z_2$ symmetry breaking versions of the 2HDM with non-zero vacuum expectation values for both Higgs doublets (Mixed Model). We consider two SM-like scenarios: with 125 GeV $h$ and 125 GeV $H$. We have applied the condition for cancellation of quadratic divergences in the type II 2HDM in order to derive masses of the heavy scalars. Solutions of two relevant conditions were found in the considered SM-like scenarios. After applying the current LHC data for the observed 125 GeV Higgs boson, the precision electroweak data test and lower limits on the mass of $H^{+}$, the allowed region of parameters shrink strongly.

   hep-phNPB(2018)·20 citations
8. 08*

   The hadronic interaction model SIBYLL 2.3c and Feynman scaling

   Felix Riehn🇵🇹 · Hans P. Dembinski🇩🇪 · Ralph Engel🇩🇪 · Anatoli Fedynitch🇩🇪 · Thomas K. Gaisser🇺🇸 · Todor Stanev🇺🇸

   The Monte Carlo model Sibyll has been designed for efficient simulation of hadronic multiparticle production up to the highest energies as needed for interpreting cosmic ray measurements. For more than 15 years, version 2.1 of Sibyll has been one of the standard models for air shower simulation. Motivated by data of LHC and fixed-target experiments and a better understanding of the phenomenology of hadronic interactions, we have developed an improved version of this model, version 2.3, which has been released in 2016. In this contribution we present a revised version of this model, called Sibyll 2.3c, that is further improved by adjusting particle production spectra to match the expectation of Feynman scaling in the fragmentation region. After a brief introduction to the changes implemented in Sibyll 2.3 and 2.3c with respect to Sibyll 2.1, the current predictions of the model for the depth of shower maximum, the number of muons at ground, and the energy spectrum of muons in extensive air showers are presented.

   hep-phPoS(2018)·255 citations
9. 09*

   Role of QCD compositeness in the production of scalar and tensor mesons through single-photon annihilation $e^{+}{e}^{-}\to {\gamma }^{\ast }\to \gamma S(T)$

   Alexandr G. Chumakov🇷🇺 · Thomas Gutsche🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Ivan Schmidt🇨🇱

   We study the exclusive production of scalar $S=0^{++}$ and tensor $T=2^{++}$ mesons through single-photon annihilation $e^{+}{e}^{-}\to {\gamma }^{\ast }\to \gamma S(T)$. Using QCD compositeness of the involved hadrons considered as quark-antiquark systems, the prediction for the scaling of the differential cross sections of these processes is $d\sigma /dt\sim 1/s^3$ at large $s$. We further derive the scaling of the ${\gamma }^{\ast }\to \gamma S$ and ${\gamma }^{\ast }\to \gamma T$ transition form factors: $F_{{\gamma }^{\ast }\gamma S}(s)\sim 1/s$ and $F_{{\gamma }^{\ast }\gamma T}(s)\sim 1/s^2$. Results for the respective cross sections of the scalar and tensor meson production are presented. Note, when scalar and tensor mesons are considered as tetraquark systems of two tightly bound color diquarks, corresponding to them transition form factors and differential cross sections have the same falloffs as in case of quark-antiquark picture. For other tetraquark or two-hadron molecules configurations the transition form factors $F_{{\gamma }^{\ast }\gamma S(T)}(s)$ and the differential cross section $d\sigma /dt$ have additional $1/s$ and $1/s^2$ falloffs, respectively.

   hep-phPRD(2017)·1 citation
10. 10*

    The impact of the LHCb $B^{\pm }$ production cross-section on parton distribution functions and determining the mass of heavy quarks

    A. Aleedaneshvar🇮🇷 · Ali N. Khorramian🇮🇷

    In this work, the impact of recent measurements of heavy-flavour production in $pp$ collisions on parton distribution functions (PDFs) and their uncertainties is studied. In this regard, the absolute and normalised cross sections of beauty hadron production measured by LHCb at center-of-mass energy of 7 TeV and 13 TeV are separately included in the next-to-leading order (NLO) global QCD analysis together with the measurements of the inclusive and heavy-flavour production cross sections at HERA. It is illustrated that the heavy-flavour data of the LHCb experiment impose additional constraints on the PDFs, especially on the gluon distribution at low partonic fractions $x$ of the proton momentum. One of the most important results of the present analysis is the significant reduction of the gluon uncertainties in the region less than $x=10^{-4}$ that can play a crucial rule in many areas of high energy physics investigations.

    hep-phNPA(2018)·4 citations
11. 11*

    The $D{\bar{D}}^{\ast }$ interaction with isospin zero in an extended hidden gauge symmetry approach

    Bao-Xi Sun🇨🇳 · Da-Ming Wan🇨🇳 · Si-Yu Zhao🇨🇳

    The $D{\bar{D}}^{\ast }$ interaction via a $\rho$ or $\omega$ exchange is constructed within an extended hidden gauge symmetry approach, where the strange quark is replaced by the charm quark in the $SU(3)$ flavor space. With this $D{\bar{D}}^{\ast }$ interaction, a bound state slightly lower than the $D{\bar{D}}^{\ast }$ threshold is generated dynamically in the isospin zero sector by solving the Bethe-Salpeter equation in the coupled-channel approximation, which might correspond to the $X(3872)$ particle announced by many collaborations. This formulism is also used to study the $B{\bar{B}}^{\ast }$ interaction, and a $B{\bar{B}}^{\ast }$ bound state with isospin zero is generated dynamically, which has no counterpart listed in the review of the Particle Data Group. Furthermore, the one-pion exchange between the $D$ meson and the ${\bar{D}}^{\ast }$ is analyzed precisely, and we do not think the one-pion exchange potential need be considered when the Bethe-Salpeter equation is solved.

    hep-phCPC(2018)·6 citations
12. 12*

    Cold light dark matter in extended seesaw models

    Sami Boulebnane🇧🇪 · Julian Heeck🇧🇪 · Anne Nguyen🇧🇪 · Daniele Teresi🇧🇪

    We present a thorough discussion of light dark matter produced via freeze-in in two-body decays A -> B DM. If A and B are quasi-degenerate, the dark matter particle has a cold spectrum even for keV masses. We show this explicitly by calculating the transfer function that encodes the impact on structure formation. As examples for this setup we study extended seesaw mechanisms with a spontaneously broken global U(1) symmetry, such as the inverse seesaw. The keV-scale pseudo-Goldstone dark matter particle is then naturally produced cold by the decays of the quasi-degenerate right-handed neutrinos.

    hep-phastro-ph.COJCAP(2018)·56 citations
13. 13*

    Momentum distribution of particles created in space-time-dependent colliding laser pulses

    I. A. Aleksandrov🇷🇺 · G. Plunien🇩🇪 · V. M. Shabaev🇷🇺

    We study the pair-production process in the presence of two counterpropagating linearly polarized short laser pulses. By means of a nonperturbative technique, we take into account the full coordinate dependence of the external field going beyond the dipole and standing-wave approximations. In particular, we analyze the momentum distribution of particles created. It is demonstrated that the spatial variations of the laser pulses may play a crucial role. The more accurate treatment reveals a number of prominent features: the pair-production probabilities become considerably smaller, the quantitative behavior of the momentum spectra changes dramatically, and the pulse shape effects become much less pronounced. The results of our study are expected to be very important for future theoretical and experimental investigations.

    hep-phPRD(2017)·53 citations
14. 14*

    On the precise determination of the Tsallis parameters in proton - proton collisions at LHC energies

    T. Bhattacharyya🇿🇦 · J. Cleymans🇿🇦 · L. Marques🇧🇷 · S. Mogliacci🇿🇦 · M.W. Paradza🇿🇦

    A detailed analysis is presented of the precise values of the Tsallis parameters obtained in $p-p$ collisions for identified particles, pions, kaons and protons at the LHC at three beam energies $\sqrt{s}=0.9,2.76$ and $7$ TeV. Interpolated data at $\sqrt{s}=$ 5.02 TeV have also been included. It is shown that the Tsallis formula provides reasonably good fits to the $p_T$ distributions in $p-p$ collisions at the LHC using three parameters $dN/dy$, $T$ and $q$. However, the parameters $T$ and $q$ depend on the particle species and are different for pions, kaons and protons. As a consequence there is no $m_T$ scaling and also no universality of the parameters for different particle species.

    hep-phphysics.data-anJ.Phys.G(2018)·48 citations
15. 15*

    New low-$Q^2$ measurements of the ${\gamma }^{\ast }N\to \Delta (1232)$ Coulomb quadrupole form factor, pion cloud parametrizations and Siegert's theorem

    G. Ramalho🇧🇷

    The novel measurements of the ${\gamma }^{\ast }N\to \Delta (1232)$ Coulomb quadrupole form factor in the range $Q^2=0.04$--0.13 GeV${}^2$ changed the trend of the previous data. With the new data the electric and Coulomb form factors are both in remarkable agreement with estimates of the pion cloud contributions to the quadrupole form factors at low $Q^2$. The pion cloud contributions to the electric and Coulomb form factors can be parametrized by the relations $G_E\propto G_{En}/\left(1+\frac{Q^2}{2M_{\Delta }(M_{\Delta }-M)}\right)$ and $G_C\propto G_{En}$, where $G_{En}$ is the neutron electric form factor, and $M$, $M_{\Delta }$ are the nucleon and $\Delta$ masses, respectively. Those parametrizations are in full agreement with Siegert's theorem, which states that $G_E=\frac{M_{\Delta }-M}{2M_{\Delta }}{G}_C$ at the pseudothreshold, when $Q^2=-(M_{\Delta }-M{)}^2$, and improve previous parametrizations. Also a small valence quark component estimated by a covariant quark model contributes to this agreement. The combination of the new data with the new parametrization for $G_E$ concludes an intense period of studying the ${\gamma }^{\ast }N\to \Delta (1232)$ quadrupole form factors at low $Q^2$, with the agreement between theory and data.

    hep-phhep-exhep-latnucl-ex+1EPJA(2018)·22 citations
16. 16*

    Global extraction of the parton-to-kaon fragmentation functions at NLO in QCD

    R. J. Hernández-Pinto🇲🇽 · M. Epele🇦🇷 · D. de Florian🇦🇷 · R. Sassot🇦🇷 · M. Stratmann🇩🇪

    In this document, we present the global QCD analysis of parton-to-kaon fragmentation functions at next-to-leading order accuracy using the latest experimental information on single-inclusive kaon production in electron-positron annihilation, lepton-nucleon deep-inelastic scattering, and proton-proton collisions. An extended analysis of this work can be found in Ref.[1].

    hep-phJ.Phys.Conf.Ser.(2017)·5 citations
17. 17*

    A Comprehensive Renormalisation Group Analysis of the Littlest Seesaw Model

    Tanja Geib🇩🇪 · Stephen F. King🇬🇧

    We present a comprehensive renormalisation group analysis of the Littlest Seesaw model involving two right-handed neutrinos and a very constrained Dirac neutrino Yukawa coupling matrix. We perform the first ${\chi }^2$ analysis of the low energy masses and mixing angles, in the presence of renormalisation group corrections, for various right-handed neutrino masses and mass orderings, both with and without supersymmetry. We find that the atmospheric angle, which is predicted to be near maximal in the absence of renormalisation group corrections, may receive significant corrections for some non-supersymmetric cases, bringing it into close agreement with the current best fit value in the first octant. By contrast, in the presence of supersymmetry, the renormalisation group corrections are relatively small, and the prediction of a near maximal atmospheric mixing angle is maintained, for the studied cases. Forthcoming results from T2K and NOvA will decisively test these models at a precision comparable to the renormalisation group corrections we have calculated.

    hep-phPRD(2018)·16 citations
18. 18*

    Master integrals for the NNLO virtual corrections to $\mu e$ scattering in QED: the planar graphs

    Pierpaolo Mastrolia🇮🇹 · Massimo Passera🇮🇹 · Amedeo Primo🇮🇹 · Ulrich Schubert🇺🇸

    We evaluate the master integrals for the two-loop, planar box-diagrams contributing to the elastic scattering of muons and electrons at next-to-next-to leading-order in QED. We adopt the method of differential equations and the Magnus exponential series to determine a canonical set of integrals, finally expressed as a Taylor series around four space-time dimensions, with coefficients written as combination of generalised polylogarithms. The electron is treated as massless, while we retain full dependence on the muon mass. The considered integrals are also relevant for crossing-related processes, such as di-muon production at $e^{+}{e}^{-}$-colliders, as well as for the QCD corrections to $top$-pair production at hadron colliders.

    hep-phhep-thJHEP(2017)·112 citations
19. 19*

    Muonic hydrogen and the proton size

    Wayne W. Repko🇺🇸 · Duane A. Dicus🇺🇸

    We reexamine the structure of the $n=2$ levels of muonic hydrogen using a two-body potential that includes all relativistic, recoil and one loop corrections. The potential was originally derived from QED to describe the muonium atom and accounts for all contributions to order ${\alpha }^5$. Since one loop corrections are included, the anomalous magnetic moment contributions of the muon can be identified and replaced by the proton anomalous magnetic moment to describe muonic hydrogen with a point-like proton. This serves as a convenient starting point to include the dominant electron vacuum polarization corrections to the spectrum and extract the proton's mean squared radius $r_p=\sqrt{⟨r^2⟩}$. Our results are consistent with other theoretical calculations that find that the muonic hydrogen value for $r_p$ is smaller than the result obtained from electron scattering.

    hep-phnucl-thPRD(2018)·6 citations
20. 20*

    How the axial anomaly controls flavor mixing among mesons

    Francesco Giacosa🇩🇪 · Adrian Koenigstein🇩🇪 · Robert D. Pisarski🇺🇸

    It is well known that because of the axial anomaly in QCD, mesons with $J^P=0^{-}$ are close to $SU(3{)}_{\mathrm{V}}$ eigenstates: the $et{a}^{\prime }(958)$ meson is largely a singlet, and the $\eta$ meson an octet. In contrast, states with $J^P=1^{-}$ are flavor diagonal: \textit{e.g.}, the $\varphi (1020)$ is almost pure $\bar{s}s$. Using effective Lagrangians, we show how this generalizes to states with higher spin, assuming that they can be classified according to the unbroken chiral symmetry of $G_{\mathrm{fl}}=SU(3{)}_{\mathrm{L}}\times SU(3{)}_{\mathrm{R}}$. We construct effective Lagrangians from terms invariant under $G_{\mathrm{fl}}$, and introduce the concept of \textit{hetero-} and \textit{homo}chiral multiplets. Because of the axial anomaly, only terms invariant under the $Z(3{)}_{\mathrm{A}}$ subgroup of the axial $U(1{)}_{\mathrm{A}}$ enter. For heterochiral multiplets, which begin with that including the $\eta$ and ${\eta }^{\prime }(958)$, there are $Z(3{)}_{\mathrm{A}}$ invariant terms with low mass dimension which cause states to mix according to $SU(3{)}_{\mathrm{V}}$ flavor. For homochiral multiplets, which begin with that including the $\varphi (1020)$, there are no $Z(3{)}_{\mathrm{A}}$ invariant terms with low mass dimension, and so states are diagonal in flavor. In this way we predict the flavor mixing for the heterochiral multiplet with spin one, as well as for hetero- and homochiral multiplets with spin two and spin three.

    hep-phhep-latPRD(2018)·52 citations
21. 21*

    Search for Nonstandard Neutrino Interactions with IceCube DeepCore

    IceCube Collaboration: M. G. Aartsen · M. Ackermann · J. Adams · J. A. Aguilar · M. Ahlers · M. Ahrens · I. Al Samarai · D. Altmann · K. Andeen · T. Anderson · I. Ansseau · G. Anton and 308 other authors

    As atmospheric neutrinos propagate through the Earth, vacuum-like oscillations are modified by Standard-Model neutral- and charged-current interactions with electrons. Theories beyond the Standard Model introduce heavy, TeV-scale bosons that can produce nonstandard neutrino interactions. These additional interactions may modify the Standard Model matter effect producing a measurable deviation from the prediction for atmospheric neutrino oscillations. The result described in this paper constrains nonstandard interaction parameters, building upon a previous analysis of atmospheric muon-neutrino disappearance with three years of IceCube-DeepCore data. The best fit for the muon to tau flavor changing term is ${ϵ}_{\mu \tau }=-0.0005$, with a 90\% C.L. allowed range of $-0.0067<{ϵ}_{\mu \tau }<0.0081$. This result is more restrictive than recent limits from other experiments for ${ϵ}_{\mu \tau }$. Furthermore, our result is complementary to a recent constraint on ${ϵ}_{\mu \tau }$ using another publicly available IceCube high-energy event selection. Together, they constitute the world's best limits on nonstandard interactions in the $\mu -\tau$ sector.

    ↳ hep-exhep-phPRD(2018)·78 citations
22. 22*

    Determination of the strong coupling constant ${\alpha }_s(M_Z)$ in next-to-next-to-leading order QCD using H1 jet cross section measurements

    H1 collaboration: V. Andreev🇷🇺 · A. Baghdasaryan🇦🇲 · K. Begzsuren🇲🇳 · A. Belousov🇷🇺 · V. Bertone🇳🇱 · A. Bolz🇩🇪 · V. Boudry🇫🇷 · G. Brandt🇩🇪 · V. Brisson🇫🇷 · D. Britzger🇩🇪 · A. Buniatyan🇬🇧 · A. Bylinkin🇷🇺 and 135 other authors

    The strong coupling constant ${\alpha }_s(M_Z)$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic $ep$ scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of ${\alpha }_s(M_Z)$ at the $Z$-boson mass $m_Z$ are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be ${\alpha }_s(M_Z)=0.1166(19{)}_{\exp }(24{)}_{\mathrm{th}}$. Complementary, ${\alpha }_s(M_Z)$ is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value ${\alpha }_s(M_Z)=0.1147(25{)}_{\mathrm{tot}}$ obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

    ↳ hep-exhep-phEPJC(2017)·81 citations
23. 23*

    Upper bound on the Abelian gauge coupling from asymptotic safety

    Astrid Eichhorn🇩🇪 · Fleur Versteegen🇩🇪

    We explore the impact of asymptotically safe quantum gravity on the Abelian gauge coupling in a model including a charged scalar, confirming indications that asymptotically safe quantum fluctuations of gravity could trigger a power-law running towards a free fixed point for the gauge coupling above the Planck scale. Simultaneously, quantum gravity fluctuations balance against matter fluctuations to generate an interacting fixed point, which acts as a boundary of the basin of attraction of the free fixed point. This enforces an upper bound on the infrared value of the Abelian gauge coupling. In the regime of gravity couplings which in our approximation also allows for a prediction of the top quark and Higgs mass close to the experimental value [1], we obtain an upper bound approximately 35% above the infrared value of the hypercharge coupling in the Standard Model.

    ↳ hep-thgr-qchep-phJHEP(2018)·166 citations
24. 24*

    The running coupling from gluon and ghost propagators in the Landau gauge: Yang-Mills theories with adjoint fermions

    Georg Bergner🇩🇪 · Stefano Piemonte🇩🇪

    Non-Abelian gauge theories with fermions transforming in the adjoint representation of the gauge group (AdjQCD) are a fundamental ingredient of many models that describe the physics beyond the Standard Model. Two relevant examples are N=1 Supersymmetric Yang-Mills (SYM) theory and Minimal Walking Technicolor, which are gauge theories coupled to one adjoint Majorana and two adjoint Dirac fermions, respectively. While confinement is a property of N=1 SYM, Minimal Walking Technicolor is expected to be infrared conformal. We study the propagators of ghost and gluon fields in the Landau gauge to compute the running coupling in the MiniMom scheme. We analyze several different ensembles of lattice Monte Carlo simulations for the SU(2) adjoint QCD with Nf=1/2, 1, 3/2, and 2 Dirac fermions. We show how the running of the coupling changes as the number of interacting fermions is increased towards the conformal window.

    ↳ hep-lathep-phPRD(2018)·15 citations
25. 25*

    Dark Matter Annihilation into Four-Body Final States and Implications for the AMS Antiproton Excess

    Steven J. Clark🇺🇸 · Bhaskar Dutta🇺🇸 · Louis E. Strigari🇺🇸

    We consider dark matter annihilation into a general set of final states of Standard Model particles, including two-body and four-body final states that result from the decay of intermediate states. For dark matter masses ~10-10^5 GeV, we use updated data from Planck and from high gamma-ray experiments such as Fermi-LAT, MAGIC, and VERITAS to constrain the annihilation cross section for each final state. The Planck constraints are the most stringent over the entire mass range for annihilation into light leptons, and the Fermi-LAT constraints are the most stringent for four-body final states up to masses ~10^4 GeV. We consider these constraints in light of the recent AMS antiproton results, and show that for light mediators it is possible to explain the AMS data with dark matter, and remain consistent with Fermi-LAT Inner Galaxy measurements, for m_\chi ~ 60-100 GeV mass dark matter and mediator masses m_\phi / m_\chi ~< 1.

    ↳ astro-ph.HEhep-phPRD(2018)·19 citations
26. 26*

    Implications of GW related searches for IceCube

    Krijn D. de Vries🇧🇪 · Gwenhaël de Wasseige🇧🇪 · Jean-Marie Frère🇧🇪 · Matthias Vereecken🇧🇪

    At the beginning of 2016, LIGO reported the first-ever direct detection of gravitational waves. The measured signal was compatible with the merger of two black holes of about 30 solar masses, releasing about 3 solar masses of energy in gravitational waves. We consider the possible neutrino emission from a binary black hole merger relative to the energy released in gravitational waves and investigate the constraints coming from the non-detection of counterpart neutrinos, focusing on IceCube and its energy range. The information from searches for counterpart neutrinos is combined with the diffuse astrophysical neutrino flux in order to put bounds on neutrino emission from binary black hole mergers. Prospects for future LIGO observation runs are shown and compared with model predictions.

    ↳ astro-ph.HEhep-ph0 citations
27. 27*

    Safe SUSY

    Borut Bajc🇸🇮 · Nicola Andrea Dondi🇩🇰 · Francesco Sannino🇩🇰

    We investigate the short distance fate of distinct classes of not asymptotically free supersymmetric gauge theories. Examples include super QCD with two adjoint fields and generalised superpotentials, gauge theories without superpotentials and with two types of matter representation and semi-simple gauge theories such as quivers. We show that for the aforementioned theories asymptotic safety is nonperturbatively compatible with all known constraints.

    ↳ hep-thhep-lathep-phJHEP(2018)·14 citations
28. 28*

    Analysis of Ultra High Energy Muons at the INO-ICAL Using Pair-Meter Technique

    Jaydip Singh🇮🇳 · Srishti Nagu🇮🇳 · Jyotsna Singh🇮🇳

    The proposed ICAL detector at INO is a large sized underground magnetized iron detector. ICAL is designed to reconstruct muon momentum using magnetic spectrometers. Energy measurement using magnets fail for muons in TeV range, since the angular deflection of the muon in the magnetic field is negligible and the muon tracks become nearly straight. A new technique for measuring the energy of muons in the TeV range is used by the CCFR neutrino detector, known as the Pair-Meter technique. This technique estimates muon energy from measurements of the energy deposited by the muon in many layers of an iron-calorimeter through e${}^{+}$ and e${}^{-}$ pair production. In this work we have performed Geant4 based preliminary analysis for iron plates and have demonstrated the observational feasibility of very high energy muons (1TeV-1000TeV) in a large mass underground detector operating as a pair-meter. This wide range of energy spectrum will be helpful for studying the cosmic rays in the Knee region and an understanding of the atmospheric neutrino flux for the present and future ultra high-energy atmospheric neutrino experiments.

    ↳ physics.ins-dethep-phSpringer Proc.Phys.(2018)·1 citation
29. 29*

    Vacuum dynamics in the Universe versus a rigid $\Lambda =$const

    Joan Sola🇪🇸 · Adria Gomez-Valent🇪🇸 · Javier de Cruz Perez🇪🇸

    In this year, in which we celebrate 100 years of the cosmological term, $\Lambda$, in Einstein's gravitational field equations, we are still facing the crucial question whether $\Lambda$ is truly a fundamental constant or a mildly evolving dynamical variable. After many theoretical attempts to understand the meaning of $\Lambda$, and in view of the enhanced accuracy of the cosmological observations, it seems now mandatory that this issue should be first settled empirically before further theoretical speculations on its ultimate nature. In this work, we summarize the situation of some of these studies. Devoted analyses made recently show that the $\Lambda =$const. hypothesis, despite being the simplest, may well not be the most favored one. The overall fit to the cosmological observables $SNIa+BAO+H(z)+LSS+CMB$ singles out the class RVM of the "running" vacuum models, in which $\Lambda =\Lambda (H)$ is an affine power-law function of the Hubble rate. It turns out that the performance of the RVM as compared to the "concordance" $\Lambda$CDM model (with $\Lambda =$const.) is much better. The evidence in support of the RVM may reach $\sim 4\sigma$ c.l., and is bolstered with Akaike and Bayesian criteria providing strong evidence in favor of the RVM option. We also address the implications of this framework on the tension between the CMB and local measurements of the current Hubble parameter.

    ↳ astro-ph.COgr-qchep-phhep-thInt.J.Mod.Phys.A(2017)·37 citations
30. 30*

    What makes the peak structure of the $\Lambda p$ invariant-mass spectrum in the $K^{-}{}^3\mathrm{He}\to \Lambda pn$ reaction?

    Takayasu Sekihara (JAEA, Ibaraki)🇯🇵 · Eulogio Oset (Valencia U. & Valencia U., IFIC)🇪🇸 · Angels Ramos (Barcelona U., ECM & ICC, Barcelona U.)🇪🇸

    Recently a peak structure was observed near the $K^{-}pp$ threshold in the in-flight ${}^3\mathrm{He}(K^{-},\Lambda p)n$ reaction of the E15 experiment at J-PARC, which could be a signal of a $\bar{K}NN$ bound state. In order to investigate what is the origin of this peak, we calculate the cross section of this reaction, in particular based on the scenario that the $\bar{K}NN$ bound state is indeed generated and decays into $\Lambda p$. We find that the numerical result of the $\Lambda p$ invariant-mass spectrum in the $\bar{K}NN$ bound scenario is consistent with the J-PARC E15 data.

    ↳ nucl-thhep-phnucl-exActa Phys.Polon.B(2017)·2 citations
31. 31*

    Semi-Inclusive ${\pi }_0$ target and beam-target asymmetries from 6 GeV electron scattering with CLAS

    S. Jawalkar · S. Koirala · H. Avakian · P. Bosted · K.A. Griffioen · C. Keith · S.E. Kuhn · K.P. Adhikari · S. Adhikari · D. Adikaram · Z. Akbar · M.J. Amaryan and 152 other authors

    We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic ${}^{14}$NH${}_3$ target, and extracted double and single target spin asymmetries for $ep\to e^{\prime }{\pi }^{0}X$ in multidimensional bins in four-momentum transfer ($1.0<Q^2<3.2$ GeV${}^2$), Bjorken-$x$ ($0.12<x<0.48$), hadron energy fraction ($0.4<z<0.7$), transverse pion momentum ($0<P_T<1.0$ GeV), and azimuthal angle ${\varphi }_h$ between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both $x$ and $P_T$, which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on $P_T$. The $\sin 2{\varphi }_h$ moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed $\sin {\varphi }_h$ moments suggest that quark gluon correlations are significant at large $x$.

    ↳ nucl-exhep-phPLB(2018)·18 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.