Fri·Oct 7, 2016Friday·October 7, 2016

1. 01*

   $H\to {\tau }^{+}{\tau }^{-}\gamma$ as a Probe of the $\tau$ Magnetic Dipole Moment

   Iftah Galon🇺🇸 · Arvind Rajaraman🇺🇸 · Tim M. P. Tait🇺🇸

   Low energy observables involving the Standard Model fermions which are chirality-violating, such as anomalous electromagnetic moments, necessarily involve an insertion of the Higgs in order to maintain $SU(2)\times U(1)$ gauge invariance. As the result, the properties of the Higgs boson measured at the LHC impact our understanding of the associated low-energy quantities. We illustrate this feature with a discussion of the electromagnetic moments of the $\tau$-lepton, as probed by the rare decay $H\to {\tau }^{+}{\tau }^{-}\gamma$. We assess the feasibility of measuring this decay at the LHC, and show that the current bounds from lower energy measurements imply that $13\mathrm{TeV}$ running is very likely to improve our understanding of new physics contributing to the anomalous magnetic moment of the tau.

   hep-phJHEP(2016)·26 citations
2. 02*

   Factorization for the light-jet mass and hemisphere soft function

   Thomas Becher🇨🇭 · Benjamin D. Pecjak🇬🇧 · Ding Yu Shao🇨🇭

   Many collider observables suffer from non-global logarithms not captured by standard resummation techniques. Classic examples are the light-jet mass event shape in the limit of small mass and the related hemisphere soft function. We derive factorization formulas for both of these and explicitly demonstrate that they capture all logarithms present at NNLO. These formulas achieve full scale separation and provide the basis for all-order resummations. A characteristic feature of non-global observables is that the soft radiation is driven by multi-Wilson-line operators, and the ones arising here map onto those relevant for the case of narrow-cone jet cross sections. Numerically, the contributions of non-global logarithms to resummed hemisphere-mass event shapes are sizeable.

   hep-phJHEP(2016)·38 citations
3. 03*

   Fast Pairwise Conversion of Supernova Neutrinos: A Dispersion-Relation Approach

   Ignacio Izaguirre🇩🇪 · Georg Raffelt🇩🇪 · Irene Tamborra🇩🇰

   Collective pair conversion ${\nu }_e{\bar{\nu }}_e\leftrightarrow {\nu }_x{\bar{\nu }}_x$ by forward scattering, where $x=\mu$ or $\tau$, may be generic for supernova neutrino transport. Depending on the local angular intensity of the electron lepton number carried by neutrinos, the conversion rate is "fast," i.e., of the order of $\sqrt{2}{G}_{\mathrm{F}}(n_{{\nu }_e}-n_{{\bar{\nu }}_e})\gg \Delta m_{\mathrm{atm}}^2/2E$. We present a novel approach to understand these phenomena: A dispersion relation for the frequency and wave number $(\Omega ,\mathbf{K})$ of disturbances in the mean field of ${\nu }_e{\nu }_x$ flavor coherence. Run-away solutions occur in "dispersion gaps," i.e., in "forbidden" intervals of $\Omega$ and/or $\mathbf{K}$ where propagating plane waves do not exist. We stress that the actual solutions also depend on the initial and/or boundary conditions which need to be further investigated.

   hep-phastro-ph.SRPRL(2017)·244 citations
4. 04*

   Time to Go Beyond Triple-Gauge-Boson-Coupling Interpretation of $W$ Pair Production

   Zhengkang Zhang (U Michigan and DESY)🇺🇸

   $W$ boson pair production processes at $e^{+}{e}^{-}$ and $pp$ colliders have been conventionally interpreted as measurements of $WWZ$ and $WW\gamma$ triple gauge couplings (TGCs). Such interpretation is based on the assumption that new physics effects other than anomalous TGCs are negligible. While this "TGC dominance assumption" was well-motivated and useful at LEP2 thanks to precision electroweak constraints, it is already challenged by recent LHC data. In fact, contributions from anomalous $Z$ boson couplings that are allowed by electroweak precision data but neglected in LHC analyses, being enhanced at high energy, can even dominate over those from the anomalous TGCs considered. This limits the generality of the anomalous TGC constraints derived in current analyses, and necessitates extension of the analysis framework and change of physics interpretation. The issue will persist as we continue to explore the high energy frontier. We clarify and analyze the situation in the effective field theory framework, which provides a useful organizing principle for understanding Standard Model deviations in the high energy regime.

   hep-phhep-exPRL(2017)·70 citations
5. 05*

   Standard Model-Axion-Seesaw-Higgs Portal Inflation. Five problems of particle physics and cosmology solved in one stroke

   Guillermo Ballesteros🇫🇷 · Javier Redondo🇪🇸 · Andreas Ringwald🇩🇪 · Carlos Tamarit🇬🇧

   We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos $N_i$, a new color triplet $Q$ and a complex SM-singlet scalar $\sigma$, whose vacuum expectation value $v_{\sigma }\sim 10^{11}$ GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of $\sigma$ and the SM Higgs, and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model - Axion - seesaw - Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.

   hep-phastro-ph.COgr-qchep-thJCAP(2017)·281 citations
6. 06*

   Gauge Unification from Split Supersymmetric String Models

   Christos Kokorelis🇬🇷

   We discuss the unification of gauge coupling constants in non-supersymmetric open string vacua that possess the properties of Split Supersymmetry, namely the Standard Model with Higgsinos at low energies and where the Standard model spectrum is always accompanied by right handed neutrinos. These vacua achieve partial unification of two out of three (namely SU(3)${}_c$, SU(2), U(1)) running gauge couplings, possess massive gauginos and light Higgsinos at low energies and also satisfy $si{n}^2{\theta }_w(M_s)=3/8$. These vacua are based on four dimensional orbifold $Z_3\times Z_3$ compactifications of string IIA orientifolds with D6-branes intersecting at angles, where the (four dimensional) chiral fermions of the Standard Model appear as opens strings streching between the intersections of seven dimensional objects the so called D6-branes.

   hep-phhep-thPoS(2016)·3 citations
7. 07*

   Effective field theory for pions and a dilatonic meson

   Maarten Golterman🇺🇸 · Yigal Shamir🇮🇱

   Numerical simulations of QCD-like theories which are chirally broken but exhibit a very small beta function reveal a flavor-singlet scalar, or "dilatonic meson," which is much lighter than any other states except pions. We develop a systematic low-energy expansion for the pions and the dilatonic meson, in which the presence of the latter is attributed to an approximate scale symmetry. In order to justify the power counting we invoke the Veneziano limit, in which the number of flavors $N_f$ in the fundamental representation grows in proportion with the number of colors $N_c$, while the ratio $N_f/N_c$ is kept close to, but below, the critical value where the conformal window is entered.

   hep-phhep-latPoS(2016)·23 citations
8. 08*

   Charm quark and meson production in association with single-jet at the LHC

   Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

   We discuss charm quark/antiquark and charmed meson production in association with one extra jet (gluon, quark, antiquark) at the LHC. The calculations are performed both in collinear and $k_T$-factorization approaches. Different unintegrated gluon distribution functions are used in the $k_T$-factorization approach. Several predictions for the LHC are presented. We show distributions in rapidity and transverse momenta of $c$/$\bar{c}$ (or charmed mesons) and the associated jet as well as some two-dimensional observables. Interesting correlation effects are predicted, \textit{e.g.} in azimuthal angles ${\phi }_{c\bar{c}}$ and ${\phi }_{c\text{-jet}}$. We have also discussed a relation of the $2\to 2$ and $2\to 3$ partonic calculations in the region of large transverse momenta of charm quarks/antiquarks as well as the similarity of the next-to-leading order collinear approach and the $k_T$-factorization approach with the KMR unintegrated parton distribution functions. Integrated cross sections for $D^0$ + jet production for ATLAS detector acceptance and for different cuts on jet transverse momenta are also presented.

   hep-phPRD(2016)·16 citations
9. 09*

   Phenomenological Implications of Very Special Relativity

   Alekha C. Nayak🇮🇳 · Pankaj Jain🇮🇳

   We discuss several phenomenological implications of Very Special Relativity (VSR). It is assumed that there is a small violation of Lorentz invariance and the true symmetry group of nature is a subgroup called SIM(2). This symmetry group postulates the existence of a fundamental or preferred direction in space-time. We study its implications by using an effective action which violates Lorentz invariance but respects VSR. We find that the problem of finding the masses of fundamental fermions is in general intractable in the presence of VSR term. The problem can be solved only in special cases which we pursue in this paper. We next determine the signal of VSR in torsion pendulum experiment as well as clock comparison experiment. We find that VSR predicts a signal which is different from other Lorentz violating theories and hence a dedicated data analysis is needed in order to impose reliable limits. Assuming that signal is absent in data we determine the limits that can be imposed on the VSR parameters. We also study the implications of VSR in particle decay experiments taking the charged pion and kaon decay as an example. The effective interaction between the charged pion and the final state leptons is related to the fundamental VSR mass terms through a loop calculation. We also predict a shift in the angular dependence of the decay products due to VSR. In particular we find that these no longer display azimuthal symmetry with respect to the momentum of the pion. Furthermore the azimuthal and polar angle distributions show time dependence with a period of a sidereal day. This time dependence provides us with a novel method to test VSR in future experiments.

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

    Can Tonne-Scale Direct Detection Experiments Discover Nuclear Dark Matter?

    A. Butcher🇬🇧 · R. Kirk🇬🇧 · J. Monroe🇬🇧 · S. M. West🇬🇧

    Models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to Standard Model nuclei. We examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular DEAP-3600 and XENON1T. In our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. We calculate the number of events required to distinguish these spectra from those of a standard point-like WIMP state with a decaying exponential recoil spectrum. In the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from WIMPs at the $3\sigma$ level in a single experiment. Given the total exposure time of DEAP-3600 and XENON1T we find that at best a $2\sigma$ distinction is possible by these experiments individually, while $3\sigma$ sensitivity is reached for a range of parameters by the combination of the two experiments. We show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a WIMP at greater than $3\sigma$.

    hep-phastro-ph.COhep-exJCAP(2017)·19 citations
11. 11*

    NNLO QCD corrections for Drell-Yan $p_T^Z$ and ${\varphi }^{\ast }$ observables at the LHC

    A. Gehrmann-De Ridder🇨🇭 · T. Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · A. Huss🇨🇭 · T.A. Morgan🇬🇧

    Drell-Yan lepton pairs with finite transverse momentum are produced when the vector boson recoils against (multiple) parton emission(s), and is determined by QCD dynamics. At small transverse momentum, the fixed order predictions break down due to the emergence of large logarithmic contributions. This region can be studied via the $p_T^Z$ distribution constructed from the energies of the leptons, or through the ${\varphi }^{\ast }$ distribution that relies on the directions of the leptons. For sufficiently small transverse momentum, the ${\varphi }^{\ast }$ observable can be measured experimentally with better resolution. We study the small $p_T^Z$ and ${\varphi }^{\ast }$ distributions up to next-to-next-to-leading order (NNLO) in perturbative QCD. We compute the ${\varphi }^{\ast }$ distributions for the fully inclusive production of lepton pairs via $Z/{\gamma }^{\ast }$ to NNLO and normalise them to the NNLO cross sections for inclusive $Z/{\gamma }^{\ast }$ production. We compare our predictions with the ${\varphi }^{\ast }$ distribution measured by the ATLAS collaboration during LHC operation at 8 TeV. We find that at moderate to large values of ${\varphi }^{\ast }$, the NNLO effects are positive and lead to a substantial improvement in the theory-data comparison compared to next-to-leading order (NLO). At small values of $p_T^Z$ and ${\varphi }^{\ast }$, the known large logarithmic enhancements emerge through and we identify the region where resummation is needed. We find an approximate relationship between the values of $p_T^Z$ and ${\varphi }^{\ast }$ where the large logarithms emerge and find perturbative consistency between the two observables.

    hep-phJHEP(2016)·85 citations
12. 12*

    Inclusive four-jet production: a study of Multi-Regge kinematics and BFKL observables

    Francesco Caporale🇪🇸 · Francesco Giovanni Celiberto🇮🇹 · Grigorios Chachamis🇪🇸 · Agustín Sabio Vera🇪🇸

    A study of differential cross sections for the production of four jets in multi-Regge kinematics is presented, the main focus lying on azimuthal angle dependences. The theoretical setup consists in the jet production from a single BFKL ladder with a convolution of three BFKL Green functions, where two forward/backward jets are always tagged in the final state. Furthermore, the tagging of two further jets in more central regions of the detectors with a relative separation in rapidity from each other is requested. It is found, as result, that the dependence on the transverse momenta and the rapidities of the two central jets can be considered as a distinct signal of the onset of BFKL dynamics.

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

    Oscillations in counting statistics

    Grzegorz Wilk🇵🇱 · Zbigniew Wlodarczyk🇵🇱

    The very large transverse momenta and large multiplicities available in present LHC experiments on pp collisions allow a much closer look at the corresponding distributions. Some time ago we discussed a possible physical meaning of apparent log-periodic oscillations showing up in p_T distributions (suggesting that the exponent of the observed power-like behavior is complex). In this talk we concentrate on another example of oscillations, this time connected with multiplicity distributions P(N). We argue that some combinations of the experimentally measured values of P(N) (satisfying the recurrence relations used in the description of cascade-stochastic processes in quantum optics) exhibit distinct oscillatory behavior, not observed in the usual Negative Binomial Distributions used to fit data. These oscillations provide yet another example of oscillations seen in counting statistics in many different, apparently very disparate branches of physics further demonstrating the universality of this phenomenon.

    hep-phnucl-thEPJ Web Conf.(2017)·3 citations
14. 14*

    An $A_4$ realization of inverse seesaw: neutrino masses, ${\theta }_{13}$ and leptonic non-unitarity

    Biswajit Karmakar🇮🇳 · Arunansu Sil🇮🇳

    We provide an $A_4$ based flavor symmetric scenario to accommodate the inverse seesaw mechanism for explaining light neutrino masses and mixing. We find that the lepton mixing, in particular the tri-bimaximal mixing pattern and its deviation through nonzero ${\theta }_{13}$, is originated solely from the flavor structure of the lepton number violating contribution of the neutral lepton mass matrix. Here we discuss in detail how a nonzero value of ${\theta }_{13}$ is correlated with the other parameters in the framework and its impact on the Dirac CP phase $\delta$. We also analyze the non-unitarity effects on lepton mixing matrix and its implication in terms of the lepton flavor violating decays, etc..

    hep-phPRD(2017)·41 citations
15. 15*

    One-point fluctuation analysis of the high-energy neutrino sky

    Michael R. Feyereisen🇳🇱 · Irene Tamborra🇩🇰 · Shin'ichiro Ando🇳🇱

    We perform the first one-point fluctuation analysis of the high-energy neutrino sky. This method reveals itself to be especially suited to contemporary neutrino data, as it allows to study the properties of the astrophysical components of the high-energy flux detected by the IceCube telescope, even with low statistics and in the absence of point source detection. Besides the veto-passing atmospheric foregrounds, we adopt a simple model of the high-energy neutrino background by assuming two main extra-galactic components: star-forming galaxies and blazars. By leveraging multi-wavelength data from Herschel and Fermi, we predict the spectral and anisotropic probability distributions for their expected neutrino counts in IceCube. We find that star-forming galaxies are likely to remain a diffuse background due to the poor angular resolution of IceCube, and we determine an upper limit on the number of shower events that can reasonably be associated to blazars. We also find that upper limits on the contribution of blazars to the measured flux are unfavourably affected by the skewness of the blazar flux distribution. One-point event clustering and likelihood analyses of the IceCube HESE data suggest that this method has the potential to dramatically improve over more conventional model-based analyses, especially for the next generation of neutrino telescopes.

    ↳ astro-ph.HEastro-ph.IMhep-phJCAP(2017)·27 citations
16. 16*

    Photohadronic scenario in interpreting the February-March 2014 flare of 1ES 1011+496

    Sarira Sahu🇲🇽 · Alberto Rosales de León🇲🇽 · Luis Salvador Miranda🇿🇦

    The extraordinary multi-TeV flare from 1ES 1011 +496 during February-March 2014 was observed by MAGIC telescopes for 17 nights and the average spectrum of the whole period has a non-trivial shape. We have used the photohadronic model and a template EBL model to explain the average spectrum which fits well to the flare data. The spectral index $\alpha$ is the only free parameter in our model. We have also shown that the non-trivial nature of the spectrum is due to the change in the behavior of the optical depth above $\sim 600$ GeV $\gamma$-ray energy accompanied with the high SSC flux.

    ↳ astro-ph.HEhep-phEPJC(2017)·11 citations
17. 17*

    Isospin decomposition of the ${\gamma }^{(\ast )}N\to N^{\ast }$ transitions as input for constructing models of neutrino-induced reactions in the nucleon resonance region

    H. Kamano🇯🇵 · S. X. Nakamura🇯🇵 · T.-S. H. Lee🇺🇸 · T. Sato🇯🇵

    We present our recent efforts to determine the matrix elements associated with the transition between the nucleon and a nucleon resonance induced by the vector current, which are necessary ingredients for models of neutrino-induced reactions in the resonance region. This is accomplished by making the comprehensive analysis of the data for various meson photo- and electro-production reactions off the nucleon within a sophisticated coupled-channels framework, which is known as the ANL-Osaka dynamical coupled-channels model. We also give a brief introduction to our project for constructing a unified neutrino reaction model conducted at the J-PARC Branch of the KEK Theory Center.

    ↳ nucl-thhep-exhep-phnucl-ex1 citation
18. 18*

    Statistics of predictions with missing higher order corrections

    Laure Berthier🇩🇰 · Jeppe Trøst Nielsen🇩🇰

    Effective operators have been used extensively to understand small deviations from the Standard Model in the search for new physics. So far there has been no general method to fit for small parameters when higher order corrections in these parameters are present but unknown. We present a new technique that solves this problem, allowing for an exact p-value calculation under the assumption that higher order theoretical contributions can be treated as gaussian distributed random variables. The method we propose is general, and may be used in the analysis of any perturbative theoretical prediction, ie.~truncated power series. We illustrate this new method by performing a fit of the Standard Model Effective Field Theory parameters, which include eg.~anomalous gauge and four-fermion couplings.

    ↳ physics.data-anhep-ph2 citations
19. 19*

    Modern Dynamical Coupled-Channels Calculations for Extracting and Understanding the Nucleon Spectrum

    Hiroyuki Kamano🇯🇵

    We give an overview of recent progress in the spectroscopic study of nucleon resonances within the dynamical coupled-channels analysis of meson-production reactions. The important role of multichannel reaction dynamics in understanding various properties of nucleon resonances is emphasized.

    ↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2017)·2 citations
20. 20*

    Charged-particle multiplicity and transverse-energy distribution using the Weibull-Glauber approach in heavy-ion collisions

    Nirbhay K. Behera🇰🇷 · Sadhana Dash🇮🇳 · Bharati Naik🇮🇳 · Basanta K. Nandi🇮🇳 · Tanmay Pani🇮🇳

    The charged-particle multiplicity distribution and the transverse-energy distribution measured in heavy-ion collisions at top RHIC and LHC energies are described using the two-component model approach based on a convolution of the Monte Carlo Glauber model with the Weibull model for particle production. The model successfully describes the multiplicity and transverse-energy distribution of minimum-bias collision data for a wide range of energies. The Weibull-Glauber model can be used to determine the centrality classes in heavy-ion collisions as an alternative to the conventional negative binomial distribution (NBD)-Glauber approach.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2017)·4 citations
21. 21*

    Vector boson production in proton-lead and lead-lead collisions at the LHC and its impact on nCTEQ15 PDFs

    A. Kusina🇫🇷 · F. Lyonnet🇺🇸 · D. B. Clark🇺🇸 · E. Godat🇺🇸 · T. Jezo🇨🇭 · K. Kovarik🇩🇪 · F. I. Olness🇺🇸 · I. Schienbein🇫🇷 · J. Y. Yu🇺🇸

    We provide a comprehensive comparison of W/Z vector boson production data in proton-lead and lead-lead collisions at the LHC with predictions obtained using the nCTEQ15 PDFs. We identify the measurements which have the largest potential impact on the PDFs, and estimate the effect of including these data using a Monte Carlo reweighting method. We find this data set can provide information about both the nuclear corrections and the heavy flavor (strange) PDF components. As the proton flavor determination is dependent on nuclear corrections (from heavy target DIS, for example), this information can also help improve the proton PDFs.

    ↳ nucl-thhep-phEPJC(2017)·76 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.