Fri·Aug 25, 2017Friday·August 25, 2017

1. 01*

   Tensions and correlations in $|V_{cb}|$ determinations

   Florian U. Bernlochner🇩🇪 · Zoltan Ligeti🇺🇸 · Michele Papucci🇺🇸 · Dean J. Robinson🇺🇸

   Recently several papers extracted $|V_{cb}|$ using the Belle measurement of the exclusive $\bar{B}\to D^{\ast }\ell \bar{\nu }$ unfolded differential decay rates, available for the first time. Depending on the theoretical inputs, some of the fits yield higher $|V_{cb}|$ values, compatible with those from inclusive semileptonic $B$ decays. Since these four fits use mostly the same data, if their correlations were close to 100\%, the tension between them would be over $5\sigma$. We determine the correlations, find that the tension between the results is less than $3\sigma$, and explore what might lead to improving the consistency of the fits. We find that fits that yield the higher values of $|V_{cb}|$, also suggest large violations of heavy quark symmetry. These fits are also in tension with preliminary lattice QCD data on the form factors. Without additional experimental data or lattice QCD input, there are no set of assumptions under which the tension between exclusive and inclusive determinations of $|V_{cb}|$ can be considered resolved.

   hep-phPRD(2017)·66 citations
2. 02*

   $(g-2{)}_{\mu }$ at four loops in QED

   Peter Marquard🇩🇪 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺 · Matthias Steinhauser🇩🇪 · David Wellmann🇩🇪

   We review the four-loop QED corrections to the anomalous magnetic moment of the muon. The fermionic contributions with closed electron and tau contributions are discussed. Furthermore, we report on a new independent calculation of the universal four-loop contribution and compare with existing results.

   hep-phEPJ Web Conf.(2019)·21 citations
3. 03*

   D-brane Disformal Coupling and Thermal Dark Matter

   Bhaskar Dutta🇺🇸 · Esteban Jimenez🇺🇸 · Ivonne Zavala🇬🇧

   Conformal and Disformal couplings between a scalar field and matter occur naturally in general scalar-tensor theories. In D-brane models of cosmology and particle physics, these couplings originate from the D-brane action describing the dynamics of its transverse (the scalar) and longitudinal (matter) fluctuations, which are thus coupled. During the post-inflationary regime and before the onset of big-bang nucleosynthesis (BBN), these couplings can modify the expansion rate felt by matter, changing the predictions for the thermal relic abundance of dark matter particles and thus the annihilation rate required to satisfy the dark matter content today. We study the D-brane-like conformal and disformal couplings effect on the expansion rate of the universe prior to BBN and its impact on the dark matter relic abundance and annihilation rate. For a purely disformal coupling, the expansion rate is always enhanced with respect to the standard one. This gives rise to larger cross-sections when compared to the standard thermal prediction for a range of dark matter masses, which will be probed by future experiments. In a D-brane-like scenario, the scale at which the expansion rate enhancement occurs depends on the string coupling and the string scale.

   hep-phastro-ph.COgr-qchep-thPRD(2017)·17 citations
4. 04*

   Zero-Range Effective Field Theory for Resonant Wino Dark Matter II. Coulomb Resummation

   Eric Braaten🇺🇸 · Evan Johnson🇺🇸 · Hong Zhang🇺🇸

   Near a critical value of the wino mass where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold, low-energy winos can be described by a zero-range effective field theory (ZREFT) in which the winos interact nonperturbatively through a contact interaction and charged winos also have electromagnetic interactions. At energies near the wino-pair thresholds, the Coulomb interaction from photon exchange between charged winos must also be treated nonperturbatively. The parameters of ZREFT can be determined by matching wino-wino scattering amplitudes calculated by solving the Schrödinger equation for winos interacting through a potential due to the exchange of electroweak gauge bosons. With Coulomb resummation, ZREFT at leading order gives a good description of the low-energy two-body observables for winos.

   hep-phJHEP(2018)·28 citations
5. 05*

   Ridge Production in High-Multiplicity Hadronic Ultra-Peripheral Proton-Proton Collisions

   Stanley J. Brodsky🇺🇸 · Stanislaw D. Glazek🇵🇱 · Alfred S. Goldhaber🇺🇸 · Robert W. Brown🇺🇸

   An unexpected result at the RHIC and the LHC is the observation that high-multiplicity hadronic events in heavy-ion and proton-proton collisions are distributed as two "ridges", approximately flat in rapidity and opposite in azimuthal angle. We propose that the origin of these events is due to the inelastic collisions of aligned gluonic flux tubes that underly the color confinement of the quarks in each proton. We predict that high-multiplicity hadronic ridges will also be produced in the high energy photon-photon collisions accessible at the LHC in ultra-peripheral proton-proton collisions or at a high energy electron-positron collider. We also note the orientation of the flux tubes between the quark and antiquark of each high energy photon will be correlated with the plane of the scattered proton or lepton. Thus hadron production and ridge formation can be controlled in a novel way at the LHC by observing the azimuthal correlations of the scattering planes of the ultra-peripheral protons with the orientation of the produced ridges. Photon-photon collisions can thus illuminate the fundamental physics underlying the ridge effect and the physics of color confinement in QCD.

   hep-phCERN Proc.(2018)·2 citations
6. 06*

   Decay constants of pseudoscalar and vector $B$ and $D$ mesons in the light-cone quark model

   Nisha Dhiman🇮🇳 · Harleen Dahiya🇮🇳

   We have studied the decay constants of the pseudoscalar and the vector $B$ and $D$ mesons in the framework of the light-cone quark model. We have applied a variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of the scale parameter $\beta$ in different potential models. Furthermore, using the known values of the constituent quark masses of $u$, $d$, $s$, $c$ and $b$ quarks, we have obtained the numerical results for the decay constants. We have also compared our results with the other theoretical calculations and the existing experimental results. The present work predictions have many phenomenological applications in the domain of $CP$ violation and also in the determination of the CKM matrix elements.

   hep-phEur.Phys.J.Plus(2018)·19 citations
7. 07*

   Deep inelastic scattering in the dipole picture at next-to-leading order

   B. Ducloué🇫🇮 · H. Hänninen🇫🇮 · T. Lappi🇫🇮 · Y. Zhu🇫🇮

   We study quantitatively the importance of the recently derived NLO corrections to the DIS structure functions at small x in the dipole formalism. We show that these corrections can be significant and depend on the factorization scheme used to resum large logarithms of energy into renormalization group evolution with the BK equation. This feature is similar to what has recently been observed for single inclusive forward hadron production. Using a factorization scheme consistent with the one recently proposed for the single inclusive cross section, we show that it is possible to obtain meaningful results for the DIS cross sections.

   hep-phnucl-thPRD(2017)·63 citations
8. 08*

   Decay widths of the excited ${\Omega }_b$ baryons

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

   The LHCb Collaboration recently observed five narrow ${\Omega }_c^0$ resonances, and measured their masses and widths through the decays ${\Omega }_c^0\to {\Xi }_c^{+}{K}^{-}$. Motivated by this discovery, and also by the fact that the ground-state bottom baryon ${\Omega }_b^{-}$ with spin-1/2 was already found experimentally, we perform theoretical investigation of the spin-1/2 and spin-3/2, ${\Omega }_b$, baryons by calculating decay width of their first orbitally and radially excited states to ${\Xi }_b^0{K}^{-}$. For this purpose, we employ QCD sum rule method on the light-cone by including into analysis the $K$ meson distribution amplitudes up to twist-4. Obtained analytical expressions are utilized to extract parameters of these decay processes which may be useful for forthcoming experimental studies of bottom baryons.

   hep-phhep-exhep-latPRD(2017)·37 citations
9. 09*

   Determination of the strong coupling constant ${\alpha }_s(m_Z)$ from measurements of the total cross section for top-antitop quark production

   Thomas Klijnsma🇨🇭 · Siegfried Bethke🇩🇪 · Günther Dissertori🇨🇭 · Gavin P. Salam🇨🇭

   We present a determination of the strong coupling constant ${\alpha }_s(m_Z)$ using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS collaboration, we extract individual values of ${\alpha }_s(m_Z)$ from measurements by different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. The determinations are then combined using a likelihood-based approach, where special emphasis is put on a consistent treatment of theoretical uncertainties and of correlations between various sources of systematic uncertainties. Our final combined result is ${\alpha }_s(m_Z)=0.1177_{-0.0036}^{+0.0034}$.

   hep-phhep-exEPJC(2017)·49 citations
10. 10*

    Hadronic decays of B_c mesons with flavor SU(3)_F symmetry

    Bhubanjyoti Bhattacharya🇺🇸 · Alexey A Petrov🇺🇸

    We study implications of a recent observation of non-leptonic $B_c^{+}\to D^0{K}^{+}$ decay and a bound on $B_c^{+}\to D^0{\pi }^{+}$ transition on CP-violating asymmetries in $B_c$ decays. In the U-spin symmetry limit, we derive a relation between the CP-asymmetries in the $B_c^{+}\to D^0{K}^{+}$ and $B_c^{+}\to D^0{\pi }^{+}$ channels and the corresponding branching ratios. We also derive several relations between non-leptonic $B_c$ decays into the final states with $D$ mesons in the flavor $SU(3{)}_F$ limit. We point out that a combined study of $SU(3{)}_F$ amplitudes in these decays can be used to constrain the angle $\gamma$ of the Cabibbo-Kobayashi-Maskawa (CKM) matrix.

    hep-phhep-exPLB(2017)·7 citations
11. 11*

    Towards parton distribution functions with small-$x$ resummation: HELL 2.0

    Marco Bonvini🇮🇹 · Simone Marzani🇮🇹 · Claudio Muselli🇮🇹

    In global fits of parton distribution functions (PDFs) a large fraction of data points, mostly from the HERA collider, lies in a region of $x$ and $Q^2$ that is sensitive to small-$x$ logarithmic enhancements. Thus, the proper theoretical description of these data requires the inclusion of small-$x$ resummation. In this work we provide all the necessary ingredients to perform a PDF fit to deep-inelastic scattering (DIS) data which includes small-$x$ resummation in the evolution of PDFs and in the computation of DIS structure functions. To this purpose, not only we include the resummation of DIS massless structure functions, but we also consider the production of a massive final state (e.g. a charm quark), and the consistent resummation of mass collinear logarithms through the implementation of a variable flavour number scheme at small $x$. As a result, we perform the small-$x$ resummation of the matching conditions in PDF evolution at heavy flavour thresholds. The resummed results are accurate at next-to-leading logarithmic (NLL) accuracy and matched, for the first time, to next-to-next-to-leading order (NNLO). Furthermore, we improve on our previous work by considering a novel all-order treatment of running coupling contributions. These results, which are implemented in a new release of HELL, version 2.0, will allow to fit PDFs from DIS data at the highest possible theoretical accuracy, NNLO+NLL, thus providing an important step forward towards precision determination of PDFs and consequently precision phenomenology at the LHC and beyond.

    hep-phJHEP(2017)·62 citations
12. 12*

    Color Breaking Baryogenesis

    Michael J. Ramsey-Musolf🇺🇸 · Peter Winslow🇺🇸 · Graham White🇦🇺

    We propose a scenario that generates the observed baryon asymmetry of the Universe through a multi--step phase transition in which SU(3) color symmetry is first broken and then restored. A spontaneous violation of $B-L$ conservation leads to a contribution to the baryon asymmetry that becomes negligible in the final phase. The baryon asymmetry is therefore produced exclusively through the electroweak mechanism in the intermediate phase. We illustrate this scenario with a simple model that reproduces the observed baryon asymmetry. We discuss how future electric dipole moment and collider searches may probe this scenario, though future EDM searches would require an improved sensitivity of several orders of magnitude.

    hep-phPRD(2018)·54 citations
13. 13*

    Observable tensor-to-scalar ratio and secondary gravitational wave background

    Arindam Chatterjee🇮🇳 · Anupam Mazumdar🇳🇱

    In this paper we will highlight how a simple vacuum energy dominated inflection-point inflation can match the current data from cosmic microwave background radiation, and predict large primordial tensor to scalar ratio, $r\sim \mathcal{O}(10^{-3}-10^{-2})$, with observable second order gravitational wave background, which can be potentially detectable from future experiments, such as DECi-hertz Interferometer Gravitational wave Observatory (DECIGO), Laser Interferometer Space Antenna (eLISA), Cosmic Explorer (CE), and Big Bang Observatory (BBO).

    ↳ astro-ph.COgr-qchep-phPRD(2018)·9 citations
14. 14*

    Power-counting during single-field slow-roll inflation

    Peter Adshead🇺🇸 · C.P. Burgess🇨🇦 · R. Holman🇺🇸 · Sarah Shandera🇺🇸

    We elucidate the counting of the relevant small parameters in inflationary perturbation theory. Doing this allows for an explicit delineation of the domain of validity of the semi-classical approximation to gravity used in the calculation of inflationary correlation functions. We derive an expression for the dependence of correlation functions of inflationary perturbations on the slow-roll parameter $ϵ=-\dot{H}/H^2$, as well as on $H/M_p$, where $H$ is the Hubble parameter during inflation. Our analysis is valid for single-field models in which the inflaton can traverse a Planck-sized range in field values and where all slow-roll parameters have approximately the same magnitude. As an application, we use our expression to seek the boundaries of the domain of validity of inflationary perturbation theory for regimes where this is potentially problematic: models with small speed of sound and models allowing eternal inflation.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2018)·27 citations
15. 15*

    Dark Matter Searches with HAWC

    Tolga Yapici🇺🇸 · Andrew J. Smith (for the HAWC Collaboration)🇺🇸

    The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field-of-view observatory sensitive to 0.5 TeV - 100 TeV gamma-rays and cosmic-rays in the State of Puebla, Mexico at an altitude of 4100m. The HAWC observatory performed an indirect search for dark matter via GeV-TeV photons resulting from dark matter annihilation and decay considering various sources, including dwarf spheroidal galaxies (dSphs), the M31 galaxy and the Virgo cluster, as well as a combined limit using the dSphs. HAWC has not seen statistically significant excess from these sources. We searched for dark matter annihilation and decay at dark matter masses above 1 TeV. We will present the annihilation cross-section and decay lifetime limits.

    ↳ astro-ph.HEastro-ph.COhep-exhep-phPoS(2018)·8 citations
16. 16*

    Fundamental Physics from Future Weak-Lensing Calibrated Sunyaev-Zel'dovich Galaxy Cluster Counts

    Mathew Madhavacheril🇺🇸 · Nicholas Battaglia🇺🇸 · Hironao Miyatake🇯🇵

    Future high-resolution measurements of the cosmic microwave background (CMB) will produce catalogs of tens of thousands of galaxy clusters through the thermal Sunyaev-Zel'dovich (tSZ) effect. We forecast how well different configurations of a CMB Stage-4 experiment can constrain cosmological parameters, in particular the amplitude of structure as a function of redshift ${\sigma }_8(z)$, the sum of neutrino masses $\Sigma m_{\nu }$, and the dark energy equation of state $w(z)$. A key element of this effort is calibrating the tSZ scaling relation by measuring the lensing signal around clusters. We examine how the mass calibration from future optical surveys like the Large Synoptic Survey (LSST) compares with a purely internal calibration using lensing of the CMB itself. We find that, due to its high-redshift leverage, internal calibration gives constraints on cosmological parameters comparable to the optical calibration, and can be used as a cross-check of systematics in the optical measurement. We also show that in contrast to the constraints using the CMB lensing power spectrum, lensing-calibrated tSZ cluster counts can detect a minimal $\Sigma m_{\nu }$ at the 3-5$\sigma$ level even when the dark energy equation of state is freed up.

    ↳ astro-ph.COgr-qchep-phPRD(2017)·57 citations
17. 17*

    Examining the model dependence of the determination of kinetic freeze-out temperature and transverse flow velocity in small collision system

    Hai-Ling Lao🇨🇳 · Fu-Hu Liu🇨🇳 · Bao-Chun Li🇨🇳 · Mai-Ying Duan🇨🇳 · Roy A. Lacey🇺🇸

    The transverse momentum distributions of the identified particles produced in small collision systems at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) have been analyzed by four models. The first two models utilize the blast-wave model with different statistics. The last two models employ certain linear correspondences based on different distributions. The four models describe the experimental data measured by the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX), Solenoidal Tracker at RHIC (STAR), and A Large Ion Collider Experiment (ALICE) cCollaborations equally well. It is found that both the kinetic freeze-out temperature and transverse flow velocity in the central collisions are comparable with those in the peripheral collisions. With the increase of collision energy from that of the RHIC to that of the LHC, the considered quantities typically do not decrease. Comparing with the central collisions, the proton-proton collisions are closer to the peripheral collisions.

    ↳ nucl-thhep-exhep-phnucl-exNucl.Sci.Tech.(2018)·33 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.