Mon·Jan 23, 2017Monday·January 23, 2017

1. 01*

   Fragmentation to a jet in the large $z$ limit

   Lin Dai🇺🇸 · Chul Kim🇰🇷 · Adam K. Leibovich🇺🇸

   We consider the fragmentation of a parton into a jet with small radius $R$ in the large $z$ limit, where $z$ is the ratio of the jet energy to the mother parton energy. In this region of phase space, large logarithms of both $R$ and $1-z$ can appear, requiring resummation in order to have a well defined perturbative expansion. Using soft-collinear effective theory, we study the fragmentation function to a jet (FFJ) in this endpoint region. We derive a factorization theorem for this object, separating collinear and collinear-soft modes. This allows for the resummation using renormalization group evolution of the logarithms $\ln R$ and $\ln (1-z)$ simultaneously. We show results valid to next-to-leading logarithmic order for the global Sudakov logarithms. We also discuss the possibility of non-global logarithms that should appear at two-loops and give an estimate of their size.

   hep-phPRD(2017)·32 citations
2. 02*

   Study of radially excited $D_s(2^1{S}_0)$ and $D_{sJ}^{+}(2632)$

   Yu Tian🇨🇳 · Ze Zhao🇨🇳 · Ailin Zhang🇨🇳

   The $J^P=0^{-}$ radial excitation $D_s(2^1{S}_0)$ is anticipated to have mass $2650$ MeV (denoted with $D_s(2650)$) though it has not been observed. $D_s(2650)$ is anticipated to be observed in inclusive $e^{+}{e}^{-}$ and $pp$ collisions in $D^{\ast }K$ channel. $D_s(2650)$ can be produced from hadronic decays of higher excited resonances. In a ${}^3{P}_0$ model, hadronic production of $D_s(2650)$ has been studied, relevant decay widths have been estimated. The hadronic decays of $D_s(3P)$ have been explored in detail, and the dominant decay channels have been pointed out. Two hadronic decay channels of $D_{sJ}^{+}(2632)$ were observed by SELEX, but have not been observed by any other experiment. Hadronic decays of $D_{sJ}^{+}(2632)$ in different assignments have been explored in the ${}^3{P}_0$ model. In view of the hadronic decay manner of $D_{sJ}^{+}(2632)$ , we conclude that $D_{sJ}^{+}(2632)$ cannot be a conventional charmed strange $c\bar{s}$ meson.

   hep-phhep-exCPC(2017)·4 citations
3. 03*

   In-medium parton branching beyond eikonal approximation

   Liliana Apolinário🇵🇹

   The description of the in-medium modifications of partonic showers has been at the forefront of current theoretical and experimental efforts in heavy-ion collisions. It provides a unique laboratory to extend our knowledge frontier of the theory of the strong interactions, and to assess the properties of the hot and dense medium (QGP) that is produced in ultra-relativistic heavy-ion collisions at RHIC and the LHC. The theory of jet quenching, a commonly used alias for the modifications of the parton branching resulting from the interactions with the QGP, has been significantly developed over the last years. Within a weak coupling approach, several elementary processes that build up the parton shower evolution, such as single gluon emissions, interference effects between successive emissions and corrections to radiative energy loss of massive quarks, have been addressed both at eikonal accuracy and beyond by taking into account the Brownian motion that high-energy particles experience when traversing a hot and dense medium. In this work, by using the setup of single gluon emission from a color correlated quark-antiquark pair in a singlet state ($q\bar{q}$ antenna), we calculate the in-medium gluon radiation spectrum beyond the eikonal approximation. The results show that we are able to factorize broadening effects from the modifications of the radiation process itself. This constitutes the final proof that a probabilistic picture of the parton shower evolution holds even in the presence of a QGP.

   hep-phFew Body Syst.(2017)·0 citations
4. 04*

   Non-minimally coupled gravity and vacuum stability

   Olga Czerwińska🇵🇱 · Zygmunt Lalak🇵🇱 · Marek Lewicki🇵🇱 · Paweł Olszewski🇵🇱

   We investigate the properties of vacuum decay taking into account a non-minimal coupling to gravity. We extend the standard thin-wall solution to include the non-minimal coupling and verify its validity by comparison with a full numerical study. We also investigate the implications of a~large cosmological constant whose influence on the geometry boosts the tunneling rate. Our analysis shows that the influence of the non-minimal coupling differs significantly between the cases of Minkowski and deSitter backgrounds.

   hep-phPoS(2017)·3 citations
5. 05*

   Interaction of real and virtual $p\bar{p}$ pairs in $J/\psi \to p\bar{p}\gamma (\rho ,\omega )$ decays

   A. I. Milstein🇷🇺 · S. G. Salnikov🇷🇺

   The $p\bar{p}$ invariant mass spectra of the processes $J/\psi \to p\bar{p}\omega$, $J/\psi \to p\bar{p}\rho$, and $J/\psi \to p\bar{p}\gamma$ close to the $p\bar{p}$ threshold are calculated by means of the $N\bar{N}$ optical potential. The potential model for $N\bar{N}$ interaction in the ${}^1{S}_0$ state is proposed. The parameters of the model are obtained by fitting the cross section of $N\bar{N}$ scattering together with the $p\bar{p}$ invariant mass spectra of the $J/\psi$ decays. Good agreement with the available experimental data is achieved. Using our potential and the Green's function approach we also describe the peak in the ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ invariant mass spectrum in the decay $J/\psi \to \gamma {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ in the energy region near the $N\bar{N}$ threshold.

   hep-phnucl-thNPA(2017)·18 citations
6. 06*

   A flavor dependent gauge symmetry, Predictive radiative seesaw and LHCb anomalies

   P. Ko🇰🇷 · Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

   We propose a predictive radiative seesaw model at one-loop level with a flavor dependent gauge symmetry $U(1{)}_{x{B}_3-xe-\mu +\tau }$ and Majorana fermion dark matter. For the neutrino mass matrix, we obtain an $A_1$ type texture (with two zeros) that provides us several predictions such as the normal ordering for the neutrino masses. We analyze the constraints from lepton flavor violations, relic density of dark matter, and collider physics for the new $U(1{)}_{x{B}_3-xe-\mu +\tau }$ gauge boson. Within the allowed region, the LHCb anomalies in $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and $B\to K{\ell }^{+}{\ell }^{-}$ with $\ell =e$ or $\mu$ can be resolved, and such $Z^{\prime }$ could be also observed at the LHC.

   hep-phhep-exPLB(2017)·53 citations
7. 07*

   Neutrino mixing and $R_K$ anomaly in $U(1{)}_X$ models: a bottom-up approach

   Disha Bhatia🇮🇳 · Sabyasachi Chakraborty🇮🇳 · Amol Dighe (Tata Inst.)🇮🇳

   We identify a class of $U(1{)}_X$ models which can explain the $R_K$ anomaly and the neutrino mixing pattern, by using a bottom-up approach. The different $X$-charges of lepton generations account for the lepton universality violation required to explain $R_K$. In addition to the three right-handed neutrinos needed for the Type-I seesaw mechanism, these minimal models only introduce an additional doublet Higgs and a singlet scalar. While the former helps in reproducing the quark mixing structure, the latter gives masses to neutrinos and the new gauge boson $Z^{\prime }$. Our bottom-up approach determines the $X$-charges of all particles using theoretical consistency and experimental constraints. We find the parameter space allowed by the constraints from neutral meson mixing, rare $b\to s$ decays and direct collider searches for $Z^{\prime }$. Such a $Z^{\prime }$ may be observable at the ongoing run of the Large Hadron Collider with a few hundred fb${}^{-1}$ of integrated luminosity.

   hep-phJHEP(2017)·70 citations
8. 08*

   Pseudoscalar-pole contribution to the $(g_{\mu }-2)$: a rational approach

   Pere Masjuan🇪🇸 · Pablo Sanchez-Puertas🇨🇿

   We employ a mathematical framework based on rational approximants in order to calculate the pseudoscalar-pole piece of the hadronic light-by-light contribution to the anomalous magnetic moment of the muon, $a_{\mu }^{\text{HLbL};P}$. The method is systematic and data based, profiting from over 13 different collaborations, and able to ascribe, for the first time, a systematic uncertainty which provides for the model independence. As a result, we obtain $a_{\mu }^{\text{HLbL};P}=94.3(5.3)\times 10^{-11}$, which uncertainty is well below the one foreseen at future experiments measuring the $(g_{\mu }-2)$.

   hep-phPRD(2017)·485 citations
9. 09*

   Parton Distribution Functions, ${\alpha }_s$ and Heavy-Quark Masses for LHC Run II

   S. Alekhin🇩🇪 · J. Blümlein🇩🇪 · S. Moch🇩🇪 · R. Placakyte🇩🇪

   We determine a new set of parton distribution functions (ABMP16), the strong coupling constant ${\alpha }_s$ and the quark masses $m_c$, $m_b$ and $m_t$ in a global fit to next-to-next-to-leading order (NNLO) in QCD. The analysis uses the $\overline{\mathrm{MS}}$ scheme for ${\alpha }_s$ and all quark masses and is performed in the fixed-flavor number scheme for $n_f=3,4,5$. Essential new elements of the fit are the combined data from HERA for inclusive deep-inelastic scattering (DIS), data from the fixed-target experiments NOMAD and CHORUS for neutrino-induced DIS, and data from Tevatron and the LHC for the Drell-Yan process and the hadro-production of single-top and top-quark pairs. The theory predictions include new improved approximations at NNLO for the production of heavy quarks in DIS and for the hadro-production of single-top quarks. The description of higher twist effects relevant beyond the leading twist collinear factorization approximation is refined. At NNLO we obtain the value ${\alpha }_s^{(n_f=5)}(M_Z)=0.1147\pm 0.0008$.

   hep-phPRD(2017)·608 citations
10. 10*

    Inclusive production of small radius jets in heavy-ion collisions

    Zhong-Bo Kang🇺🇸 · Felix Ringer🇺🇸 · Ivan Vitev🇺🇸

    We develop a new formalism to describe the inclusive production of small radius jets in heavy-ion collisions, which is consistent with jet calculations in the simpler proton-proton system. Only at next-to-leading order (NLO) and beyond, the jet radius parameter $R$ and the jet algorithm dependence of the jet cross section can be studied and a meaningful comparison to experimental measurements is possible. We are able to consistently achieve NLO accuracy by making use of the recently developed semi-inclusive jet functions within Soft Collinear Effective Theory (SCET). In addition, single logarithms of the jet size parameter ${\alpha }_s^n{\ln }^{n}R$ are resummed to next-to-leading logarithmic (NLL${}_R$) accuracy. The medium modified semi-inclusive jet functions are obtained within the framework of SCET with Glauber gluons that describe the interaction of jets with the medium. We present numerical results for the suppression of inclusive jet cross sections in heavy ion collisions at the LHC and the formalism developed here can be extended directly to corresponding jet substructure observables.

    hep-phnucl-thPLB(2017)·78 citations
11. 11*

    Superheavy Thermal Dark Matter and Primordial Asymmetries

    Joseph Bramante🇨🇦 · James Unwin🇺🇸

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to $10^{10}$ GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

    hep-phastro-ph.COJHEP(2017)·71 citations
12. 12*

    Is well-tempered neutralino in MSSM still alive after 2016 LUX results?

    Marcin Badziak🇵🇱 · Marek Olechowski🇵🇱 · Paweł Szczerbiak🇵🇱

    It is pointed out that a bino-dominated well-tempered bino-higgsino in the Minimal Supersymmetric Standard Model (MSSM) with heavy non-SM- like scalars can satisfy the 2016 LUX constraints on the scattering cross-section of dark matter on nuclei only if $\tan \beta$ is smaller than about 3. This, together with the Higgs mass constraint, sets a lower bound on the stops masses of about 25 TeV. The LUX constraints can be satisfied for larger $\tan \beta$ if the non-SM-like Higgs bosons are light enough. However, this region of parameter space is strongly constrained by recent LHC results of the Higgs boson searches. Satisfying both the LUX and LHC constraints requires the non-SM-like Higgs bosons to be lighter than about 400 GeV and $\tan \beta$ below about 8. This implies a lower bound on the stop masses of about 1.5 TeV. This small corner of the parameter space will be probed in the near future by the direct detection experiments, the LHC Higgs searches and precision Higgs coupling measurements. The recent LUX constraints improved also the lower mass limit on higgsino-dominated well-tempered neutralino to about 950 (900) GeV with heavy (light) MSSM-like Higgs doublet, assuming the stop masses below 10 TeV.

    hep-phPLB(2017)·48 citations
13. 13*

    Transverse densities of octet baryons from chiral effective field theory

    Jose Manuel Alarcón🇺🇸 · Astrid N. Hiller Blin🇪🇸 · C. Weiss🇺🇸

    Transverse densities describe the distribution of charge and current at fixed light-front time and provide a frame-independent spatial representation of hadrons as relativistic systems. We calculate the transverse densities of the octet baryons at peripheral distances b = O(M_pi^{-1}) in an approach combining chiral effective field theory (ChEFT) and dispersion analysis. The densities are represented as dispersive integrals of the imaginary parts of the baryon electromagnetic form factors in the timelike region (spectral functions). The spectral functions on the two-pion cut at t > 4 M_pi^2 are computed using relativistic ChEFT with octet and decuplet baryons in the EOMS renormalization scheme. The calculations are extended into the rho-meson mass region, using a dispersive method that incorporates the timelike pion form-factor data. The approach allows us to construct densities at distances b > 1 fm with controlled uncertainties. Our results provide insight into the peripheral structure of nucleons and hyperons and can be compared with empirical densities and lattice-QCD calculations.

    hep-phnucl-thFew Body Syst.(2017)·3 citations
14. 14*

    Lorentz invariance violation as an explanation of muon excess in Auger data

    Gaurav Tomar🇮🇳

    The Auger collaboration has observed the number of muons which is higher than its prediction by existing hadronic interaction models. We explain this excess of muons by using Lorentz invariance violation (LIV) in photon sector. As an outcome of Lorentz invariance violation, the dispersion relation of photon gets modified, which we use for the calculation of ${\pi }^0$ decay width. In the Auger data of primary energy $10^{9.8}<E(\text{mbox}GeV)<10^{10.2}$, we find that the neutral pion decay width is suppressed in comparison to its standard model (SM) counterpart. As a result, we get a large number of muons explaining the observed muon excess. We consider Planck suppressed LIV at order $\mathcal{O}(p^2/M_{\text{mbox}Pl}^2)$ for studying the photon sector, which is in agreement with the current bounds, and not as tightly constrained as LIV at order $\mathcal{O}(p/M_{\text{mbox}Pl})$.

    hep-phPRD(2017)·11 citations
15. 15*

    Single top polarisation as a window to new physics

    J.A. Aguilar-Saavedra🇪🇸 · C. Degrande🇨🇭 · S. Khatibi🇮🇷

    We discuss the effect of heavy new physics, parameterised in terms of four-fermion operators, in the polarisation of single top (anti-)quarks in the $t$-channel process at the LHC. It is found that for operators involving a right-handed top quark field the relative effect on the longitudinal polarisation is twice larger than the relative effect on the total cross section. This enhanced dependence on possible four-fermion contributions makes the polarisation measurements specially interesting, in particular at high momenta.

    hep-phhep-exPLB(2017)·22 citations
16. 16*

    A non-planar two-loop three-point function beyond multiple polylogarithms

    Andreas von Manteuffel🇺🇸 · Lorenzo Tancredi🇩🇪

    We consider the analytic calculation of a two-loop non-planar three-point function which contributes to the two-loop amplitudes for $t\bar{t}$ production and $\gamma \gamma$ production in gluon fusion through a massive top-quark loop. All subtopology integrals can be written in terms of multiple polylogarithms over an irrational alphabet and we employ a new method for the integration of the differential equations which does not rely on the rationalization of the latter. The top topology integrals, instead, in spite of the absence of a massive three-particle cut, cannot be evaluated in terms of multiple polylogarithms and require the introduction of integrals over complete elliptic integrals and polylogarithms. We provide one-fold integral representations for the solutions and continue them analytically to all relevant regions of the phase space in terms of real function, extracting all imaginary parts explicitly. The numerical evaluation of our expressions becomes straightforward in this way.

    hep-phhep-thJHEP(2017)·134 citations
17. 17*

    Transplanckian Censorship and Global Cosmic Strings

    Matthew J. Dolan🇦🇺 · Patrick Draper🇺🇸 · Jonathan Kozaczuk🇺🇸 · Hiren Patel🇺🇸

    Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections between various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants $f<M_p$ and large winding numbers $n>M_p/f$, the EFT is under control and the string cores undergo topological inflation, which may be either of exponential or power-law type. We show that the exterior spacetime is nonsingular and equivalent to a decompactifying cigar geometry, with the radion rolling in a potential generated by axion flux. Signals are able to circumnavigate infinite straight strings in finite but exponentially long time, $t\sim e^{\Delta a/M_p}$. For finite loops of supercritical string in asymptotically flat space, we argue that if topological inflation occurs, then topological censorship implies transplanckian censorship, or that external observers are forbidden from threading the loop and observing the full excursion of the axion.

    ↳ hep-thgr-qchep-phJHEP(2017)·48 citations
18. 18*

    Correlated primordial spectra in effective theory of inflation

    Jinn-Ouk Gong🇰🇷 · Masahide Yamaguchi🇯🇵

    We derive a direct correlation between the power spectrum and bispectrum of the primordial curvature perturbation in terms of the Goldstone mode based on the effective field theory approach to inflation. We show examples of correlated bispectra for the parametrized feature models presented by the Planck collaboration. We also discuss the consistency relation and the validity of our explicit correlation between the power spectrum and bispectrum.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2017)·11 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.